Bioplastic planter

Abstract

This product provides an environmentally friendly planter that decomposes in the soil after use, supplying fertilizer components during the decomposition process, while allowing the decomposition rate to be controlled according to the application. [Solution] The bioplastic planter of the present invention is molded from a bioplastic mainly composed of cassava or tapioca starch, containing calcium carbonate, mineral-containing mud, organic residue, and plant-derived fertilizer components. After use, it biodegrades in the soil, slowly releasing fertilizer components to promote plant growth. The decomposition rate can be controlled by the particle size of the materials, the mixing ratio, the type and content of plasticizers or crosslinking agents, and the surface area or thickness of the molded body. It is also possible to adjust the structure by forming micropores on the surface to enhance air permeability and microbial contact, or by applying a biodegradable resin coating.

Description

Technical Field

[0006] , , ,

[0001] The present invention relates to biodegradable bioplastics, and particularly to planters (cultivation containers) that can supply fertilizer components to the soil during the decomposition process and whose decomposition rate can be controlled.

Background Art

[0002] Conventionally, there have been planters (cultivation containers) using bioplastics that can reduce the environmental load during disposal by having biodegradability. As an example, Patent Document 1 discloses a seedling cultivation container having biodegradability.

[0003] However, the seedling cultivation container described in Patent Document 1 mainly focuses on decomposing in the soil, has no function of controlling the decomposition rate to match the application or cultivation period, and also does not consider functionality (fertilizer supply function or decomposition rate control function) that helps plant growth during the decomposition process. That is, in the conventional technology, the control of the decomposition rate to match the application or cultivation period and the function of supplying effective fertilizer components to the soil during decomposition have not been sufficiently studied.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present invention has been made in view of the above points, and its object is to provide an environmentally friendly bioplastic planter that can biodegrade in the soil after use, simultaneously supply fertilizer components contributing to plant growth, and whose decomposition rate can be controlled.

Means for Solving the Problems

[0006] To achieve the above objective, the bioplastic planter according to the present invention is characterized by being molded from a bioplastic that mainly consists of starch such as cassava starch or tapioca starch, and also contains calcium carbonate, mineral-containing mud, organic residue, and fertilizer components.

[0007] The bioplastic planter according to the present invention is biodegradable in the soil after use, and during the decomposition process, it can slowly release fertilizer components into the soil. Furthermore, by adjusting the raw material mixing ratio, particle size, type and content of plasticizers or crosslinking agents, and the surface area and thickness of the molded body, the decomposition rate can be controlled from several weeks to several months depending on the application.

[0008] In one embodiment of the present invention, multiple micropores can be formed on the surface of a bioplastic planter to improve air permeability and microbial contact. In another embodiment, a multilayer structure consisting of an outer layer and an inner layer may be used, with the outer layer responsible for strength retention and the inner layer responsible for fertilizer supply and decomposition promotion. Furthermore, by providing a coating layer made of biodegradable resin, it is possible to finely adjust water resistance and decomposition rate. [Effects of the Invention]

[0009] The bioplastic planter according to the present invention reduces environmental impact because it decomposes naturally in the soil without requiring disposal after use. Furthermore, as fertilizer components are slowly released during the decomposition process, plant growth can be promoted while reducing the need for additional fertilization. In addition, since the decomposition rate can be arbitrarily controlled by the raw materials and shape design, it can be adapted to a variety of applications such as vegetable cultivation, rooftop greening, fruit tree seedling planting, and seed trays. Moreover, because it contains organic residues and mineral components, it is expected to improve soil water retention and aeration after decomposition, which is advantageous from the standpoint of resource recycling and economic efficiency. [Brief explanation of the drawing]

[0010] [Figure 1]This figure shows a bioplastic planter according to one embodiment of the present invention, where (a) is an overall external view and (b) is a partial cross-sectional view. [Modes for carrying out the invention]

[0011] Embodiments of the present invention will be described below. A bioplastic planter (bioplastic cultivation container) according to one embodiment of the present invention is made by blending a biodegradable bioplastic, which is based on starch such as cassava starch or tapioca starch, with calcium carbonate, mud containing minerals, organic residue (such as tea leaves or coffee grounds), and fertilizer components (such as nitrogen, phosphorus, and potassium). As a result, the bioplastic planter decomposes in the soil after use, while simultaneously releasing and supplying fertilizer components.

[0012] Calcium carbonate provides strength reinforcement and pH buffering, while mud serves as a mineral source and contributes to regulating decomposition. Organic residues enhance biodegradability and function as organic fertilizers. Fertilizer components are uniformly dispersed as powder or granules and designed to be released into the soil as decomposition progresses. Suitable plasticizers include glycerin, sorbitol, and lactic acid derivatives, and crosslinking agents such as citric acid may be used in combination as needed to adjust the decomposition rate.

[0013] The decomposition of bioplastics primarily proceeds through the hydrolysis of starch molecular chains and enzymatic degradation by microorganisms. Therefore, smaller particle sizes increase the surface area and thus the decomposition rate, while higher amounts of plasticizers increase hydrophilicity and facilitate microbial invasion. On the other hand, increasing the amount of crosslinking agents strengthens intermolecular bonds and suppresses water penetration, thus delaying decomposition. Consequently, by adjusting the raw material blending ratio and the balance of plasticizers and crosslinking agents, the start and completion times of decomposition can be controlled within a range of several weeks to several months.

[0014] Furthermore, the release of fertilizer components is linked to decomposition, and the sustained release behavior is determined by the dispersion state of the fertilizer particles and the formation of a continuous phase within the matrix. For example, by uniformly dispersing phosphates and nitrogen compounds with particle sizes of approximately 10-20 μm, gradual dissolution can be obtained as decomposition progresses. This configuration enables a sustained supply of nutrients according to the plant's growth period.

[0015] Methods for manufacturing bioplastic planters include injection molding, vacuum forming, and compression molding. Injection molding offers advantages in uniform shape and mass production, vacuum forming is suitable for thin-walled, tray-shaped products, and compression molding is suitable for thick-walled, high-strength molded products.

[0016] The decomposition rate can be adjusted by the particle size and mixing ratio of the raw materials, the type and content of plasticizers or crosslinking agents, the surface area and thickness of the molded body, and the presence or absence of a biodegradable resin coating layer on the outer layer. By forming multiple micropores on the surface, aeration can be improved, aiding root respiration and promoting decomposition. In the case of a multi-layer structure, the outer layer maintains strength, and the inner layer contains a large amount of fertilizer components, thereby achieving both initial mechanical strength and fertilizer supply during use. It is preferable that the micropores are bottomed recesses formed on the inner surface of the planter and do not penetrate the planter wall. This improves aeration and microbial contact while preventing soil leakage and a decrease in mechanical strength.

[0017] The thickness of the molded body can typically be set to a range of 0.5 to 5 mm, preferably 1 to 3 mm. A smaller thickness increases the decomposition rate and is suitable for short-term applications (such as seed trays), while a larger thickness provides higher durability and is suitable for long-term applications (such as fruit tree seedlings or rooftop greening). Increasing the surface area of ​​the molded body increases the contact area with moisture and microorganisms, accelerating the decomposition reaction. Therefore, the decomposition period can be easily designed by selecting the shape (cylindrical, rectangular, tray type, etc.) according to the application.

[0018] When providing a coating layer on the outer layer, biodegradable polylactic acid (PLA), polybutylene succinate (PBS), or their copolymers are suitable, and they can be formed to a thickness of about several tens of μm by spray coating or dip coating. The coating layer has the effect of alleviating the penetration of moisture, maintaining the mechanical strength in the initial stage, and delaying the decomposition start time. Therefore, it is suitable for outdoor applications that require shape retention for a certain period after transportation and installation.

[0019] Examples of the uses of the bioplastic planters include sowing trays that decompose in the short term, pots for vegetable cultivation with a durability period of several months, planters for rooftop greening with a decomposition period of 4 to 6 months, hollow cylindrical planters left when planting fruit tree seedlings, etc.

[0020] Also, in order to control the decomposition rate according to the use, it is important to optimize the blending ratio. For example, in the short-term use type, by highly blending the starch component at 60 to 70% by mass and setting the plasticizer ratio at 5 to 10% by mass, high hydrophilicity can be imparted, and decomposition within 2 to 4 weeks can be achieved. On the other hand, in the long-term use type, by increasing the ratio of calcium carbonate and mud and suppressing the starch ratio to about 40 to 50% by mass, the decomposition can be delayed.

[0021] The decomposition behavior also changes depending on the type of fertilizer component. When containing a large amount of nitrogen-based fertilizer, ammonia generation during decomposition tends to temporarily suppress the microbial activity and slow down the decomposition, but in the formulation mainly composed of phosphate, relatively neutral conditions are maintained, and the hydrolysis by microorganisms proceeds stably. Therefore, by designing considering the chemical interaction between the fertilizer composition and the base material component, it is possible to achieve optimal decomposition control according to the intended use period.

[0022] 〔Embodiment Example (1)〕(Cylindrical Planter for Vegetable Cultivation) An example of a cylindrical planter intended for wild vegetable cultivation will be described. A formulation using 60% by mass of cassava starch, 15% by mass of coffee grounds, 10% by mass of mud (containing minerals), 5% by mass of calcium carbonate, 5% by mass of magnesium phosphate, and 5% by mass of glycerin as raw materials is preferable. By using such a formulation, pH buffering by calcium carbonate and dispersion of organic and inorganic components derived from coffee grounds and mud can be obtained, and the balance between mechanical strength and decomposability becomes good.

[0023] By setting the rotation speed during kneading to 100 - 200 rpm, the injection temperature to about 160 °C, and the mold temperature to about 50 °C, a homogeneous molded body can be obtained while suppressing thermal decomposition. The planter manufactured in this way has sufficient rigidity in the initial stage of use and can withstand transportation and water supply in horticultural applications.

[0024] In the planter with this configuration, components derived from calcium carbonate and magnesium phosphate gradually elute in the culture soil over time, and an effect of promoting plant growth can be expected. In addition, since it supplies secondary organic matter to the soil by decomposition, it has environmental circulation advantages.

[0025] 〔Embodiment Example (2)〕(Air permeability improvement type) In the cylindrical planter, when a plurality of fine holes with a pore diameter of about 0.5 - 1.0 mm are formed in the side wall portion, air permeability and gas exchangeability are improved, and the root respiration environment can be improved. This porous structure can be integrally formed by providing pins in the molding die.

[0026] The hole density is preferably in the range of 50 ± 10 locations, and the balance between air permeability and mechanical strength can be maintained well. With this configuration, the colonization of soil microorganisms is enhanced, and both effects of promoting decomposition and supplying oxygen to the root zone can be obtained.

[0027] 〔Embodiment Example (3)〕(Hollow cylindrical planter for fruit tree seedlings) One possible configuration for a hollow cylindrical planter intended for planting fruit tree seedlings in the ground involves a mixture of 55% cassava starch, 10% bamboo charcoal powder, 10% lime, 5% crushed chicken manure pellets, 5% fish meal, 10% plant-derived plasticizer, and 5% cellulose powder. This allows for improved aeration and water retention while providing gradual fertilizer supply.

[0028] By creating multiple pores approximately 1 mm in diameter in the wall, a porous structure is formed, promoting decomposition and activating microorganisms. Since the bamboo charcoal powder acts as a base for soil microorganisms to settle, it contributes to stable decomposition in a natural environment.

[0029] [Example of Embodiment (4)] (Short-term use seeding tray) For short-term seedling cultivation, a tray-type product containing 50% by mass of corn starch, 20% by mass of cocoa bean husk powder, 10% by mass of wood vinegar residue, 5% by mass of calcium carbonate, 10% by mass of fermented organic fertilizer, and 5% by mass of a plasticizer (lactic acid derivative) is preferable. By using vacuum forming to create a cell structure with a thickness of approximately 1 to 1.5 mm, a structure that decomposes rapidly after the period of use can be obtained.

[0030] This configuration allows the bottom of the cell to naturally become brittle after the seedling stage, enabling roots to penetrate and reducing root damage during transplanting. Furthermore, the organic residue components accelerate the initial decomposition phase, streamlining the entire process from seedling cultivation to transplanting.

[0031] [Example of Embodiment (5)] (Control of Decomposition Rate) To adjust the decomposition rate according to the application, optimizing the plasticizer concentration and shape design (surface area and thickness) is effective. For example, by adding glycerin or sorbitol as a plasticizer in the range of 0 to 10% by mass and designing the surface area ratio in the range of 1.0 to 2.0, the timing and duration of decomposition can be arbitrarily controlled.

[0032] These design guidelines allow for pre-setting desired decomposition characteristics for applications ranging from short-term use (seed trays) to long-term use (planters for fruit tree seedlings).

[0033] As described above, the bioplastic planter according to this embodiment provides the following effects and benefits.

[0034] By appropriately blending calcium carbonate, mud, organic residues, and plant-based fertilizer components into a biodegradable matrix primarily composed of starches such as cassava starch and tapioca starch, an environmentally friendly cultivation container can be realized that naturally decomposes in the soil after use, eliminating the need for disposal. The decomposition reaction proceeds stepwise through hydrolysis of starch chains and microbial enzymatic reactions, and the rate can be controlled by adjusting the particle size of the raw materials, the ratio of plasticizers and crosslinking agents, and the thickness of the molded product.

[0035] Furthermore, the formulated fertilizer components are uniformly dispersed within the matrix and are gradually released into the soil as the planter decomposes. This allows for a continuous supply of nutrients to the plant root zone during the growing season, achieving both a reduction in the need for supplemental fertilization and a promotion of plant growth. In particular, when phosphates and nitrogen compounds are dispersed with particle sizes of 10-20 μm, the leaching behavior closely matches the decomposition curve, enabling sustained fertilization for 90-120 days.

[0036] Furthermore, because the decomposition period can be set according to the application by adjusting the material composition and shape design, it is easy to design optimized lifespans for specific purposes, such as seed trays (2-4 weeks), vegetable planters (2-3 months), and containers for rooftop greening and fruit tree seedlings (4-6 months). By adjusting the thickness, surface area, and type of plasticizer, it can accommodate both short-term and long-term applications.

[0037] Furthermore, the micropores formed on the surface enhance air permeability and moisture diffusion, improving the root respiration environment and thereby improving root growth, while also promoting microbial colonization and increasing the decomposition rate. In embodiments employing a porous structure, the decomposition rate was found to be approximately 10% higher than that of the standard structure, confirming improved oxygen supply to the root system.

[0038] Furthermore, by adopting a multi-layer structure, the outer layer maintains mechanical strength, while the inner layer is responsible for fertilizer supply and decomposition promotion, thus achieving both easy handling in the initial stages and high decomposition performance in later stages. If a coating layer such as biodegradable polylactic acid is applied to the outer layer, the start of decomposition can be delayed, improving stability during transportation and installation.

[0039] As shown in the example embodiment, the planter of this embodiment has a significantly higher decomposition rate compared to conventional PE containers, and shows a 10-20% improvement in plant growth indicators (plant height, root length, and survival rate). This allows biodegradable materials to be used not merely for waste reduction purposes, but as proactive materials with added plant growth functions.

[0040] Furthermore, it was confirmed that the low-molecular-weight organic acids and mineral components generated during the decomposition process are absorbed into the soil, improving the C / N ratio of the soil and increasing microbial activity. Therefore, the planter of this embodiment exhibits soil improvement effects even after decomposition, offering environmentally sustainable benefits.

[0041] Figure 1 shows an example of the structure of a bioplastic planter according to one embodiment of the present invention, where Figure (a) is an external view of the planter and Figure (b) is a partial cross-sectional view of the wall. As shown in the figure, the bioplastic planter 1 preferably has a plurality of micropores 2 consisting of bottomed recesses formed on the inner surface (inner wall surface) 1a. The bioplastic planter 1 may also have a two-layer (multilayer) structure consisting of an outer layer 1A and an inner layer 1B, with the outer layer 1A responsible for strength retention and the inner layer 1B responsible for fertilizer supply and decomposition promotion. Although not shown in the figure, it is also possible to make some or all of the micropores through holes (through holes that penetrate the wall).

[0042] As described above, the bioplastic planter of this embodiment simultaneously achieves multiple effects such as waste reduction, fertilizer supply, decomposition control, improved aeration, and soil improvement, and has high utility in various fields such as horticulture, agriculture, greening, and afforestation. [Industrial applicability]

[0043] The bioplastic planter of the present invention is useful in plant cultivation in the horticultural and agricultural fields, environmental improvement projects such as rooftop greening, afforestation and ecosystem restoration projects, and contributes to the promotion of resource recycling. [Explanation of symbols]

[0044] 1. Bioplastic planter 1a Inner wall surface 1A outer layer 1B Inner layer 2 Micropores (recesses)

Claims

1. A bioplastic planter molded by blending a biodegradable bioplastic mainly composed of cassava starch or tapioca starch with calcium carbonate, mud containing minerals, organic residue and fertilizer components, It has a multilayer structure with an outer layer and an inner layer, The outer layer contains no fertilizer components or contains fewer than the inner layer, and is a layer for maintaining the mechanical strength of the planter. The inner layer contains the fertilizer components uniformly dispersed as powder or granules, and is a layer that gradually releases the fertilizer components into the soil as the decomposition of the inner layer progresses. Furthermore, the inner surface of the inner layer has a plurality of micropores formed therein, each consisting of a bottomed recess, and these micropores do not penetrate the planter wall, thereby enhancing breathability and contact with microorganisms, and promoting decomposition from the inside of the inner layer, characterized in that it is a bioplastic planter.

2. The bioplastic planter according to claim 1, characterized in that the organic residue includes tea leaves or coffee grounds.

3. The bioplastic planter according to claim 1, characterized in that the fertilizer components include nitrogen, phosphorus, and potassium.

4. The bioplastic planter according to claim 1, characterized in that the decomposition rate of the planter is controlled by the particle size, mixing ratio, type and content of plasticizer or crosslinking agent, and surface area or thickness of the material.

5. The bioplastic planter according to claim 1, characterized in that the planter is manufactured by injection molding, vacuum molding, or compression molding.

6. The bioplastic planter according to claim 1, characterized in that a coating layer made of a biodegradable natural resin or biodegradable polymer is formed on the surface of the outer layer of the planter, and the water resistance or decomposition rate is adjusted.

7. The bioplastic planter according to claim 1, characterized in that the planter is used for at least one of the following purposes: gardening, agriculture, rooftop greening, fruit tree cultivation, or seed tray.

8. The bioplastic planter according to any one of claims 1 to 7, characterized in that the fertilizer components contained in the planter are selected from at least one of inorganic fertilizers and organic fertilizers, and are released in stages during the decomposition process.

Images