KR102745455B1 - Method for manufacturing slow-releasing granular fertilizers with improved coating power and reduced microplastic generation - Google Patents

Abstract

A method for manufacturing a slow-release granular fertilizer with improved coating power and reduced generation of microplastics according to an embodiment of the present invention comprises: a first step of performing a first coating on the surface of a granular fertilizer using a synthetic resin; a second step of leaving the granular fertilizer, on which the first coating is completed through the first step, at a temperature of 15 to 25°C for 24 hours to induce hardening of the synthetic resin coated on the surface of the granular fertilizer; a third step of performing a second coating on the surface of the granular fertilizer, on which the second coating is completed through the second step, using a natural coating agent mixed with a natural saturated fatty acid and natural oil; and a fourth step of performing a third coating by mixing a clay material or plant-derived powder on the surface of the granular fertilizer, on which the second coating is completed through the third step, to induce rapid hardening and surface flattening, thereby manufacturing a slow-release granular fertilizer.

Description

Method for manufacturing slow-releasing granular fertilizers with improved coating power and reduced microplastic generation

The present invention relates to a method for manufacturing a slow-release granular fertilizer with improved coating power and reduced generation of microplastics, which reduces the generation of microplastics while not reducing or rather improving coating performance by reducing the amount of chemical coating material used and increasing the ratio of natural oil with controlled saturated fatty acid content as a natural coating material.

In general, fertilizers are substances that provide nutrients to edible plants and ornamental plants or promote their growth, and can be viewed as substances that provide nutrients to plants in the form of a nutrient solution dissolved in water or moisture.

Fertilizers of this type can be classified into slow-release fertilizers, fast-release fertilizers, chemical fertilizers, and organic fertilizers.

Here, slow-release fertilizer is a term that contrasts with fast-release fertilizers, which show the effects of fertilizers applied to the soil quickly, such as ammonium sulfate, and refers to fertilizers whose effects show slowly. Fast-release fertilizers not only cause temporary concentration disorders and excessive nutrients, but are also easy to lose or become ineffective, and require a lot of effort because they have to be applied multiple times, which is a drawback.

Slow-release fertilizers are developed to compensate for the above-mentioned shortcomings of fertilizers, and various types of slow-release fertilizers are being developed as nitrogen fertilizers. The use of slow-release fertilizers can reduce the amount of chemical fertilizers used, and can reduce soil and water pollution caused by leached nutrients.

Recently, for the ease of spraying from automated devices such as drones, the development of slow-release fertilizers (SRF) and controlled-release fertilizers (CRF) that are slowly released by coating (covering) fertilizers with chemically manufactured synthetic resins such as polyethylene, polyurethane, and epoxy is active, and it is positioned as the field with the fastest growth due to its effects of reducing carbon emissions, protecting the environment, and saving labor.

In this regard, a “control-release type natural decomposition seed treatment agent covering fertilizer” has been disclosed in the past. (Hereinafter referred to as “prior art 1”)

Prior art 1 relates to a controlled-release seedbed treatment coating fertilizer, and more specifically, the present invention relates to a controlled-release seedbed treatment coating fertilizer and a method for using the same, characterized in that the fertilizer surface is coated with a mixed composition film including 20 to 60 parts by weight and 10 to 20 parts by weight of olefin resins, such as polyethylene and ethylene vinyl acetate, respectively, 5 to 30 parts by weight of a biodegradation-inducing resin, 3 to 15 parts by weight of starch, 10 to 70 parts by weight of water-insoluble talc or diatomaceous earth, and 0.2 to 2 parts by weight of anionic or cationic surfactant.

In addition, a “bio-degradable slow-release coating fertilizer” has been disclosed in the past. (Hereinafter referred to as “prior art 2”)

Prior art 2 relates to a biodegradable, slow-release coated fertilizer having a certain period of time of release and a coated portion that biodegrades over a certain period of time, by coating the surface of the fertilizer with a resin prepared by mixing a polyolefin resin and a biodegradable resin, polylatex acid, and to an eco-friendly coated fertilizer containing biodegradable polyaspartic acid before and after coating to effectively improve the growth of crops when cultivating horticultural crops and rice.

In this way, fertilizers coated with synthetic resin are increasing significantly in usage every year, but since the synthetic resin, which is the coating material, does not decompose in water and, unlike other plastic products, cannot be collected at all, most of it accumulates in the soil or flows into rivers, causing environmental problems by generating microplastics. Recently, in countries such as Europe, the United States, and China that have prioritized the use of chemical resin-coated fertilizers, microplastics in the soil have been causing growth inhibition in useful organisms and plants, and high levels of microplastics have been detected in fruits, vegetables, etc. This has become an issue, and there is an urgent need to develop technologies to reduce the use of synthetic resins manufactured chemically in the fertilizer coating process.

In addition, due to the recent Chinese government's restrictions on fertilizer exports, it has become difficult to obtain chemical fertilizers, which are mostly dependent on China. As a result, the demand for coated fertilizers that are completely effective with a single application and do not require additional spraying is growing significantly every year. However, environmental problems such as the plastic-based synthetic resins such as polyethylene, polyurethane, and epoxy, which are coating materials, do not dissolve in water at all, so most of them remain in the soil and rivers, becoming the cause of microplastics, are also coming to the fore. In particular, coated fertilizer residues are emerging as a very serious problem in that, unlike other plastic waste, they are not collected at all.

Patent Registration No. 10-0946937 (Publication Date: 2010.03.09.) Patent Registration No. 10-1096312 (Publication Date: December 20, 2011)

The present invention has been created to solve the above problems, and the purpose of the present invention is to provide a method for manufacturing a slow-release granular fertilizer with improved coating power and reduced generation of microplastics, which can minimize the use of synthetic resin by additionally coating with a natural coating agent in which a natural saturated fatty acid and natural oil are mixed in a certain ratio to partially replace the synthetic resin, thereby reducing the residual microplastics and maintaining or rather increasing the coating power of the granular fertilizer.

A method for manufacturing a slow-release granular fertilizer with improved coating power and reduced generation of microplastics according to an embodiment of the present invention comprises: a first step of performing a first coating on the surface of a granular fertilizer using a synthetic resin; a second step of leaving the granular fertilizer, on which the first coating is completed through the first step, at a temperature of 15 to 25°C for 24 hours to induce hardening of the synthetic resin coated on the surface of the granular fertilizer; a third step of performing a second coating on the surface of the granular fertilizer, on which the second coating is completed through the second step, using a natural coating agent mixed with a natural saturated fatty acid and natural oil; and a fourth step of performing a third coating by mixing a clay material or plant-derived powder on the surface of the granular fertilizer, on which the second coating is completed through the third step, to induce rapid hardening and surface flattening, thereby manufacturing a slow-release granular fertilizer.

In the method for manufacturing a complete-release granular fertilizer with improved coating power and reduced generation of microplastics according to an embodiment of the present invention, in the first step, the synthetic resin is any one of polyethylene, polyurethane, and epoxy, and the synthetic resin can be mixed on the surface of the granular fertilizer at a weight ratio of 1:0.002 to 0.004.

In the method for manufacturing a slow-release granular fertilizer with improved coating power and reduced generation of microplastics according to an embodiment of the present invention, in the third step, the natural saturated fatty acid may be one or a combination of two or more selected from the group consisting of stearic acid, tric acid, laurylic acid, myristic acid, palmitic acid, beeswax, and carnauba wax, and the natural oil may be one or a combination of two or more selected from the group consisting of palm oil, coconut oil, soybean milk, corn oil, peanut oil, palm kernel oil, sunflower oil, rapeseed oil, grapeseed oil, flax oil, cottonseed oil, olive oil, safflower oil, and lard oil, and the natural saturated fatty acid and natural oil may be mixed in a weight ratio of 1:0.1 to 0.8 and used as a natural coating agent.

In the method for manufacturing a granular fertilizer having improved coating power and reduced generation of microplastics according to an embodiment of the present invention, in the third step, the natural coating agent may be mixed in a weight ratio of 1:0.01 to 0.02 on the surface of the granular fertilizer that has been hardened through the second step to complete secondary coating.

In the method for manufacturing a slow-release granular fertilizer with improved coating power and reduced generation of microplastics according to an embodiment of the present invention, in the third step, the surface of the granular fertilizer on which the second coating is completed is rapidly hardened and surface flattened, and the clumping phenomenon between the granular fertilizers is prevented by mixing the plant-derived powder or natural clay powder in a weight ratio of 1:0.005 to 0.02 on the surface of the granular fertilizer on which the second coating is completed, thereby manufacturing a slow-release granular fertilizer.

The present invention can reduce residual microplastics due to the reduction in synthetic resin by partially replacing environmentally harmful synthetic resins and increasing the usage ratio of natural coating raw materials by the amount of reduced synthetic resins, thereby maintaining or even increasing the coating power as a controlled-release granular fertilizer.

In addition, since the present invention forms a multi-coating layer using an eco-friendly coating material on the surface of a granular fertilizer, it can minimize the loss of nutrients from the granular fertilizer, reduce green and red tide phenomena, and minimize environmental pollution problems in soil and rivers caused by residues of chemical coating materials.

In addition, the present invention can maximize the coating effect by promoting rapid hardening when a coating layer of natural materials is formed by coating the surface of a granular fertilizer coated with an eco-friendly material using powder of natural seaweed, and can also dramatically prevent the clumping phenomenon.

The present invention can reduce agricultural labor and the amount of fertilizer sprayed by controlling the ineffectiveness point of an eco-friendly fertilizer so that the fertilizer is effective according to the nutrient requirement at each stage of plant crop growth with a single fertilizer spray.

Figure 1 is a flow chart showing a method for manufacturing a complete granular fertilizer with improved coating power and reduced generation of microplastics according to an embodiment of the present invention.
Figure 2 is a graph showing the change in electrolyte concentration in water over time of a complete-release granular fertilizer according to an example and comparative example of the present invention.

Hereinafter, if it is judged that a detailed description of a related known technology may unnecessarily obscure the gist of the present invention, the detailed description will be omitted. In addition, the numbers used in the description of this specification are merely identifiers for distinguishing one component from another.

In addition, the terms used in this specification and claims should not be interpreted as limited to their dictionary meanings, and should be interpreted as meanings and concepts that conform to the technical idea of the present invention, based on the principle that the inventor can appropriately define the concept of the term in order to explain his or her invention in the best way.

Therefore, the embodiments described in this specification and the configurations illustrated in the drawings are only preferred embodiments of the present invention and do not express all of the technical ideas of the present invention. Therefore, it should be understood that various equivalents and modified examples may exist that can replace them at the time of filing this application.

A more detailed description of a preferred embodiment of the present invention will be given, but technical aspects already known will be omitted or compressed for the sake of brevity.

Figure 1 is a flow chart showing a method for manufacturing a complete granular fertilizer with improved coating power and reduced generation of microplastics according to an embodiment of the present invention.

Hereinafter, with reference to FIG. 1, a method for manufacturing a complete-release granular fertilizer with improved coating power and reduced generation of microplastics according to an embodiment of the present invention will be described in detail.

1. 1st coating stage (Stage 1, S100)

This step is a step for performing the first coating of granular fertilizer using synthetic resin as a coating agent. The process is carried out by mixing granular fertilizer and synthetic resin and uniformly coating the surface of the granular fertilizer with synthetic resin.

Here, the synthetic resin of this step is any one of polyethylene, polyurethane, and epoxy, and the synthetic resin can be mixed on the surface of the granular fertilizer at a weight ratio of 1:0.002 to 0.004 to perform the first coating.

2. Hardening stage (Stage 2, S200)

In this step, the granular fertilizer, for which the first coating has been completed through the first step (S100), is left at a temperature of 15 to 25°C (room temperature) for 24 hours to induce hardening of the synthetic resin coated on the surface of the granular fertilizer.

3. Second coating stage (Stage 3, S300)

In this step, a second coating is performed on the surface of the granular fertilizer that has been hardened through the second step (S200) using a natural coating agent mixed with natural saturated fatty acids and natural oils.

Specifically, in this step, in order to improve cracks and fissures that may occur on the surface of the granular fertilizer coated with synthetic resin in the second step (S200) through the hardening process and to enhance the coating power of the granular fertilizer, the surface of the granular fertilizer may be sufficiently coated with a natural coating agent through repeated coating once or twice or more.

In addition, the natural coating agent of the present step is a mixture of a natural saturated fatty acid and a natural oil, and the natural saturated fatty acid may be one or a combination of two or more selected from the group consisting of stearic acid, fritic acid, lauric acid, myristic acid, palmitic acid, beeswax, and carnauba wax. In addition, the natural oil may be one or a combination of two or more selected from the group consisting of palm oil, coconut oil, soybean oil, corn oil, peanut oil, palm kernel oil, sunflower oil, rapeseed oil, grapeseed oil, flax oil, cottonseed oil, olive oil, safflower oil, and lard oil.

And, in this step, pre-coating is performed on the surface of the granular fertilizer with a natural coating agent at a weight ratio of 1:0.01 to 0.02, and if necessary, post-coating can be performed on the surface of the granular fertilizer on which pre-coating is completed with a natural coating agent at a weight ratio of 1:0.01 to 0.02.

And, in this step, it is desirable that the total content of the natural coating agent used in pre-coating and post-coating be 1% or less for 100% of the granular fertilizer. This is because if the total content of the coating material exceeds 1%, a clumping phenomenon may occur between the granular fertilizer particles.

4. 3rd coating stage (Stage 4, S400)

In this step, a process is performed to manufacture a slow-release granular fertilizer by mixing clay material or plant-derived powder on the surface of the granular fertilizer on which the second coating was completed through the third step (S300) to induce rapid hardening and surface flattening, thereby performing a third coating.

Specifically, in this step, the third coating can be performed by mixing the vegetable-derived powder or natural clay powder in a weight ratio of 1:0.005 to 0.02 on the surface of the second-coated granular fertilizer to induce rapid hardening and surface flattening on the surface of the granular fertilizer while preventing clumping between the granular fertilizers. The manufacture of a slow-release granular fertilizer is completed through this third coating of the granular fertilizer.

In addition, the plant-derived powder used in this step may be one or a combination of two or more types from the group consisting of corn starch, potato starch, and seaweed powder, and the natural clay powder may be one or a combination of two or more types from the group consisting of zeolite, bentonite, attapolgite, and perlite.

In this way, the slow-release granular fertilizer manufactured through the first (S100), second (S200), third (S300), and fourth (S400) steps described above can minimize the use of synthetic resin by performing secondary coating using a natural coating agent mixed with natural saturated fatty acids and natural oils by partially replacing the synthetic resin, and can achieve the effect of maintaining or rather increasing the coating power of the granular fertilizer while reducing the residual microplastics (synthetic resin). In addition, the slow-release granular fertilizer manufactured according to the manufacturing method of the present invention has a synthetic resin content used as a coating agent that is about 20 to 50% of the synthetic resin content used as a coating agent in granular fertilizers sold on the market, and by replacing this with a natural coating agent and using it in combination, the coating power of the slow-release granular fertilizer can be maintained or rather increased, and the residual microplastics can be reduced, so it has excellent characteristics in terms of being environmentally friendly.

<Experimental example> Coating test and dissolution test

Figure 2 is a graph showing the change in the concentration of electrolyte in water over time of a complete-release granular fertilizer manufactured according to examples and comparative examples of the present invention. (Control in Figure 2 represents a comparative example, A represents Example A, and B represents Example B.)

In this experimental example, the effectiveness of a slow-release granular fertilizer manufactured by the method for manufacturing a slow-release granular fertilizer with improved coating power and reduced microplastic generation of the present invention was investigated.

That is, in order to determine the coating effect of a controlled-release slow-release granular fertilizer manufactured by a manufacturing method capable of minimizing the use of synthetic resin by additionally coating a natural coating agent mixed with natural saturated fatty acids and natural oils by partially replacing the synthetic resin with the coating agent according to the present invention, thereby maintaining or rather increasing the coating power of the fertilizer while reducing microplastic residues, an underwater dissolution test was measured through an EC test.

The change in electrolyte concentration in water over time is shown in Table 1 below, and the results represented graphically are shown in Fig. 2.

0min 10min 30min 1h 2h Comparative Example (Control) 0 4.19±0.27 10.29±0.57 16.35±0.88 24.43±0.91 Example A 0 0.46±0.02 1.53±0.14 3.41±0.11 7.051±0.51 B 0 0.77±0.05 3.42±0.32 8.45±0.32 15.37±0.21

<Control: Fertilizer coated with 0.8% synthetic resin

Example A: Fertilizer with a primary coating of 0.4% synthetic resin + a secondary coating of a natural coating agent mixed with natural fatty acids and natural oils

Example B: Fertilizer with a first coating of a natural coating agent mixed with natural fatty acid and natural oil + a second coating of 0.4% synthetic resin

Referring to Table 1 and FIG. 2 above, the comparative example is a sample manufactured by coating with a synthetic resin content of 0.8% used in the manufacture of commercially available complete granular fertilizers, Example A is a sample obtained by first coating with 0.4% synthetic resin, which is half the amount used in the comparative example, and then recoating with 1% natural oil mixed with natural saturated fatty acids after 24 hours, and then completing a third coating with 0.5% clay or plant-derived powder, and Example B is a sample obtained by reversing the order of the first and second coatings compared to Example A.

In addition, it was confirmed that Example A, a sample that was first coated with synthetic resin and then second coated with a mixture of natural saturated fatty acids and natural oils, showed the slowest water dissolution compared to the comparative example that was coated entirely with chemical resin at 0.8%. This suggests that a product obtained by reducing the amount of synthetic resin used by 50% and second coating with natural oils containing natural saturated fatty acids not only has excellent coating power, but also reduces microplastic residues due to the use of less chemical coating materials, which is very important in terms of environmental protection. This complements the shortcomings in coating power when manufacturing a slow-release fertilizer using only 100% natural materials compared to when manufacturing a slow-release fertilizer using 100% synthetic resin, and can also be used as an important indicator of environmental protection in that it can reduce microplastic residues by about 50%.

As described above, although the present invention has been specifically described by way of examples, the above-described examples are only described as preferred examples of the present invention, and therefore, the present invention should not be understood as being limited to the above-described examples, and the scope of rights of the present invention should be understood by the claims described below and their equivalent concepts.

Claims (5)

The first step is to apply a primary coating to the surface of the granular fertilizer using synthetic resin;
A second step of inducing hardening of the synthetic resin coated on the surface of the granular fertilizer by leaving the granular fertilizer, whose first coating has been completed through the first step, at a temperature of 15 to 25°C;
A third step of performing secondary coating by performing pre-coating of a natural coating agent mixed with natural saturated fatty acid and natural oil at a weight ratio of 1:0.01 to 0.02 on the surface of the granular fertilizer that has been hardened through the second step, and optionally performing post-coating of the natural coating agent at a weight ratio of 1:0.01 to 0.02 on the surface of the granular fertilizer that has been pre-coated; and
The fourth step includes manufacturing a slow-release granular fertilizer by mixing clay material or plant-derived powder on the surface of the granular fertilizer on which the second coating is completed through the third step to induce rapid hardening and surface flattening, thereby performing a third coating.
In the above first step, the synthetic resin is one of polyethylene, polyurethane, and epoxy, and the synthetic resin is mixed on the surface of the granular fertilizer at a weight ratio of 1:0.002 to 0.004.
In the third step above,
The above natural saturated fatty acid may be one or a combination of two or more selected from the group consisting of stearic acid, tric acid, laurylic acid, myristic acid, palmitic acid, beeswax, and carnauba wax.
The above natural oil may be one or a combination of two or more selected from the group consisting of palm oil, coconut oil, soybean oil, corn oil, peanut oil, palm kernel oil, sunflower oil, rapeseed oil, grape seed oil, flax oil, cottonseed oil, olive oil, safflower oil, and lard oil.
The above natural saturated fatty acid and natural oil are mixed in a weight ratio of 1:0.1 to 0.8 and used as a natural coating agent.
Method for manufacturing a complete-release granular fertilizer with reduced microplastic generation and improved coating power.
delete delete delete In paragraph 1,
In the above 4th step, the surface of the granular fertilizer on which the second coating is completed is rapidly hardened and surface flattened through the above 3rd step, and the third coating is performed by mixing the plant-derived powder or natural clay powder in a weight ratio of 1:0.005 to 0.02 on the surface of the granular fertilizer on which the second coating is completed, so as to prevent the clumping phenomenon between the granular fertilizers, thereby manufacturing a slow-release granular fertilizer.
Method for manufacturing a complete-release granular fertilizer with reduced microplastic generation and improved coating power.