Seedling-raising container and liquid composition

Abstract

This seedling-raising container contains silica particles. The silica particles include silica base particles having a particle size of 100 nm or more. The median particle size of the silica base particles is 120 nm to 800 nm in the particle size distribution of the silica base particles.

Description

Seedling container and liquid composition

[0001] The present disclosure relates to seedling containers and liquid compositions.

[0002] Patent Document 1 discloses a base paper for seedling pots, which is formed by laminating a biodegradable resin composition on a paper substrate.

[0003] Japanese Patent Application Laid-Open No. 2021-122204

[0004] The seedling pots described in Patent Document 1 are biodegradable and can be planted in the ground as they are, but the seedling pots themselves do not promote the growth of plants.

[0005] An object of the present disclosure is to provide a seedling container that can improve plant growth.

[0006] Another object of the present disclosure is to provide a liquid composition that can improve plant growth.

[0007] A seedling container according to an embodiment of the present disclosure includes silica particles. The silica particles include silica base particles having a particle size of 100 nm or more. The median particle size of the silica base particles is 120 nm or more and 800 nm or less in the particle size distribution of the silica base particles.

[0008] A liquid composition according to another embodiment of the present disclosure is a liquid composition comprising silica particles and a solvent. The silica particles include silica base particles having a particle size of 100 nm or more. The median particle size of the silica base particles is 120 nm or more and 800 nm or less in the particle size distribution of the silica base particles.

[0009] According to one embodiment of the present disclosure, a seedling container capable of improving plant growth can be provided. According to another embodiment of the present disclosure, a liquid composition capable of improving plant growth can be provided.

[0010] Fig. 1 is a scanning electron microscope image of silica particles. Fig. 2 is a scanning electron microscope image of silica particles. Fig. 3 is an explanatory diagram illustrating an example of a method for producing silica particles.

[0011] First Embodiment A seedling container according to a first embodiment (first seedling container) contains silica particles. The silica particles include silica base particles (hereinafter also referred to as base particles) having a particle size of 100 nm or more. The median particle size of the base particles is 120 nm or more and 800 nm or less in the particle size distribution of the base particles.

[0012] The silica particles are aggregates of a plurality of silica particles. ２ The silica particles may be substantially spherical particles. ２ The particles are SiO ２ In this specification, the term "major component" refers to the component with the largest content in terms of mass among the constituent components, and may be, for example, 90 mass % or more, 95 mass % or more, or 99 mass % or more based on the total mass of all the constituent components. ２ The content of is measured by X-ray fluorescence analysis. In this specification, the remaining constituent components other than the main component are also referred to as minor components.

[0013] Silica particles are composed of carbon (C), diphosphorus pentoxide (P ２ O ５ ), sulfur trioxide (SO ３ The silica particles may further contain one or more elements or compounds selected from the group consisting of chlorine (Cl), sodium (Na), and nitrogen (N) as a secondary component. Since Na, Cl, phosphorus (P), and sulfur (S) are nutrients for plant growth, the inclusion of the above elements or compounds as secondary components in the silica particles tends to be advantageous for plant growth. The silica particles may contain any of Na, Cl, P, and S as long as the effects of the seedling container of the present disclosure are obtained. ２ O ５ , S.O. ３ It is not necessary to include any of the above.

[0014] The silica particles may be secondary particles formed by agglomeration of multiple primary particles, or tertiary particles formed by agglomeration of secondary particles. That is, the silica particles may be agglomerated particles. The silica particles may also contain non-agglomerated primary particles. The average particle size of the primary particles may be, for example, 50 nm or less, 1 nm or more to 50 nm or less, or 10 nm or more to 40 nm or less. The average particle size of the primary particles may be, for example, 1 nm or more, or 10 nm or more. Whether the silica particles are agglomerated particles can be confirmed by the following procedure. First, the silica particles are immersed in an alkaline solution for 5 days. The alkaline solution may be a strong alkaline solution. Then, the surface or cross section of the silica particles removed from the alkaline solution is observed using a scanning electron microscope (SEM) or a transmission electron microscope (TEM) to confirm the presence of a primary particle or a boundary between multiple primary particles.

[0015] The silica particles include silica mother particles having a particle size of 100 nm or more. The central particle size of the mother particles is 120 nm or more and 800 nm or less in the particle size distribution of the mother particles. The "central particle size" refers to the median value of the particle size in the particle size distribution. In other words, the "central particle size" is the so-called median diameter (D50). In this specification, the particle size distribution of the mother particles is the particle size distribution calculated from the longest diameter measured for 25 or more particles (mother particles) having a particle size of 100 nm or more in an SEM image of the silica particles at 50,000 magnification, and the central particle size of the mother particles is the median value calculated from the particle size distribution. Furthermore, the mother particles may be secondary particles or tertiary particles.

[0016] The silica particles may further contain silica fine particles (hereinafter also referred to as fine particles) having a particle size of less than 100 nm. When the silica particles further contain fine particles, the median particle size of the fine particles may be 10 nm or more and less than 100 nm in the particle size distribution of the fine particles. In this specification, the particle size distribution of the fine particles is a particle size distribution calculated from the longest diameter measured for 25 or more particles (fine particles) having a particle size of less than 100 nm in an SEM image of the silica particles at 200,000 magnification, and the median particle size of the fine particles is the median calculated from the particle size distribution. In addition, the fine particles may be secondary particles or tertiary particles.

[0017] The silica particles may include both base particles and fine particles, or may include only base particles.

[0018] One or more fine particles may be attached to the outer surface of the base particle. In this specification, "attached" refers to the state in which the silica particles and the base particle are integrated to such an extent that the fine particles do not fall off when water is poured over the silica particles. Specifically, a chemical bond such as a covalent bond may exist between the fine particles and the base particle.

[0019] The silica particles may contain water-soluble silica, which is a water-soluble component. When water-soluble silica dissolves in water, it becomes silicic acid. The silicic acid is orthosilicic acid (H ４ SiO ４ ), metasilicic acid (H ２ SiO ３ In soil, silicic acid is a compound that is water-soluble and contains SiOH, such as calcium silicate (Ca ２ SiO ４ These silicates are also called available silicates, and can be absorbed by plants to promote plant growth.

[0020] The content of available silicic acid in silica particles is not particularly limited and may be 0 g / 100 g or more and 100 g / 100 g or less. The content of available silicic acid in silica particles is measured, for example, in accordance with the method described in "Soil, Water Quality and Plant Analysis Method" (Japan Soil Association, 2001). The content of available silicic acid in silica particles can be measured, for example, by the molybdenum blue method after extraction with a pH 6.2 phosphoric acid extract.

[0021] The silica particles are not particularly limited and commercially available silica particles or the like can be used, but it is preferable to use silica particles having the structure described below (hereinafter referred to as silica particles A).

[0022] The silica particles A contain silica base particles having a particle size of 100 nm or more. The content of the base particles in the silica particles A (when the base particles have fine particles described below, the content of the base particles having fine particles) may be, for example, 40 mass % or more, 60 mass % or more, 80 mass % or more, 90 mass % or more, 95 mass % or more, or 100 mass %. The median particle size of the base particles is 120 nm or more and 800 nm or less in the particle size distribution of the base particles.

[0023] The silica particles A may further contain silica fine particles having a particle size of less than 100 nm. When the silica particles A further contain fine particles, the median particle size of the fine particles is 10 nm or more and less than 100 nm in the particle size distribution of the fine particles.

[0024] The silica particles A may have fine particles on the surface of the base particle. The base particle may have a plurality of fine particles. The presence of fine particles on the surface of the base particle tends to increase the specific surface area of ​​the silica particles A. The silica particles A may include at least one of base particles having a plurality of fine particles and base particles having no fine particles, may include only base particles having a plurality of fine particles and base particles having no fine particles, or may include only base particles having a plurality of fine particles or base particles having no fine particles. The presence of fine particles in the base particle can be confirmed, for example, by observation at 200,000 magnification with an SEM.

[0025] When the silica particles A contain fine particles, the fine particles may be attached to most or all of the base particles. When the fine particles are attached to the outer surfaces of the base particles, the contact area of ​​the silica particles A as a whole with the soil tends to be large, and as a result, plant growth due to the silica particles A tends to be improved.

[0026] The base particles of silica particles A may have voids therein. The fine particles of silica particles A may also have voids therein. When the porosity of a single particle is defined as the ratio of the area occupied by voids in the cross section of a single silica particle A to the cross-sectional area of ​​the single silica particle A, the porosity of a single particle may be, for example, 0.2% to 6.0%, or 2.5% to 6.0%, or 0.2% to 2.0%, for example, 1.2%. The void ratio of the base particle may be less than 0.2% or more than 6.0%. The porosity of a single particle can also be measured, for example, by analyzing images captured by TEM.

[0027] The mother particles of the silica particles A may be secondary particles (aggregated particles) composed of a plurality of primary particles. Furthermore, the fine particles of the silica particles A may be secondary particles (aggregated particles) composed of a plurality of primary particles. The average particle size of the primary particles may be, for example, 50 nm or less, 1 nm or more to 50 nm or less, or 10 nm or more to 40 nm or less. Furthermore, the average particle size of the primary particles may be, for example, 1 nm or more, or 10 nm or more.

[0028] The base particles of silica particles A may have cracks. The term "cracks" refers to linear images on the surface of the base particles observed in an SEM image at 150,000 magnifications. The cracks may be groove-like depressions, linear scratches, steps, etc., formed on the surface of the base particles.

[0029] The specific surface area of ​​the silica particles A is, for example, 15 m ２ / g or more 200m ２ / g or less, and ２ / g. The specific surface area is the value of the surface area per unit weight. The specific surface area of ​​the silica particles A is measured, for example, by a gas adsorption measurement method using the BET method. The BET method is a method for measuring the surface area of ​​a particle by adsorbing a gas having a known adsorption occupation area onto the surface of the particle. The specific surface area of ​​the silica particles A is 15 m2 or less, as long as the effect of the seedling container of the present disclosure can be obtained. ２ / g or less than 200m ２ / g or more.

[0030] The silica particles A may be amorphous. The crystallinity of the silica particles A is confirmed by X-ray diffraction (XRD). Both the base particles and the fine particles may be amorphous.

[0031] The coefficient of variation of the silica particles A may be, for example, 0.30 or less. The coefficient of variation is the value obtained by dividing the standard deviation of the particle diameter of the silica particles A by the average particle diameter of the silica particles A. The coefficient of variation may be greater than 0.30 as long as the effects of the seedling container of the present disclosure are obtained.

[0032] The silica particles A do not contain particles having a particle size of less than 100 nm other than the mother particles and the fine particles contained in the mother particles, or even if they do, the amount of particles is very small compared to the amount of the mother particles. When the silica particles A contain particles having a particle size of less than 100 nm, the number of particles having a particle size of less than 100 nm may be 1 / 100 or less of the number of the mother particles.

[0033] Silica particles A are SiO ２ The base particles and fine particles of the silica particles A may be particles containing SiO as a main component. ２ It may be.

[0034] Silica particles A are C, P ２ O ５ , S.O. ３ The silica particles A may further contain, as a secondary component, one or more elements or compounds selected from Na, Cl, P, and Cl, as long as the effect of the seedling container of the present disclosure can be obtained. ２ O ５ , S.O. ３ The content may not necessarily be any of the above, and is not limited to the examples of the content shown below.

[0035] When silica particles A contain C, the content of C in silica particles A may be, for example, 5.0 mass% or less, 1.5 mass% or more, or even 1.5 mass%. The content of C in silica particles A can be measured using a carbon / sulfur analyzer (CS analyzer). In carbon measurement using a CS analyzer, silica particles A are dissolved in a high-frequency heating furnace in an oxygen stream. At this time, the C component contained in silica particles A is dissolved in CO, CO ２The carbon-derived gas is then measured using an infrared detector. This quantifies the amount of C contained in the silica particles A. From the quantification results, the C content in the silica particles A is calculated. The C content in the silica particles A may be less than 1.5% by mass or more than 5.0% by mass, as long as the effect of the seedling container of the present disclosure is obtained.

[0036] Silica particles A are P ２ O ５ When the silica particles A contain ２ O ５ The content of the silica particles A may be, for example, 0.1% by mass or less, or may be 0.01% by mass. ３ When the silica particles A contain ３ The content of may be, for example, 0.1 mass% or less, or may be 0.04 mass%. When the silica particles A contain Cl, the content of Cl in the silica particles A may be, for example, 0.05 mass% or less, or may be 0.02 mass%. When the silica particles A contain Na, the content of Na in the silica particles A may be, for example, less than 0.01 mass%, or may be 0.01 mass% or more as long as the effect of the seedling container of the present disclosure is obtained. P in the silica particles A ２ O ５ , S.O. ３ The Cl content is measured by, for example, X-ray fluorescence analysis, and the Na content is measured by, for example, emission spectroscopy.

[0037] When the silica particles A contain N, the N content in the silica particles A may be, for example, 1.0 mass% or less, 0.8 mass% or less, or 0.73 mass% or less. The N content in the silica particles A is measured, for example, by an inert gas fusion method.

[0038] N is ammonia nitrogen (NH ４ In the silica particles A, N may be present as ammonia nitrogen (NH ４ When present as ammonia nitrogen (NH ４The content of nitrate nitrogen (NO -N) may be, for example, 5.0 mg / 100 g or less, 4.0 mg / 100 g or less, 3.0 mg / 100 g or less, 1.6 mg / 100 g or less, or 1.5 mg / 100 g. ３ The silica particles A may contain nitrate nitrogen (NO 3 -N) for example, less than 0.1 mg / 100 g, or less than 0.05 mg / 100 g. ３ -N). The contents of ammonia nitrogen and nitrate nitrogen in silica particles A are measured, for example, in accordance with the method described in "Soil Environmental Analysis Methods" (Soil Environmental Analysis Methods Editorial Committee, 1997). The content of ammonia nitrogen in silica particles A can be measured, for example, by the indophenol method using a potassium chloride solution as the extraction solution. The content of nitrate nitrogen in silica particles A can be measured, for example, by extraction with a potassium chloride solution, followed by alkali reduction, and then by the diazo dye method.

[0039] The base exchange capacity (CEC) (also referred to as fertilizer retention capacity) of the silica particles A may be, for example, 1.0 meq / 100 g or less, 0.6 meq / 100 g or less, or 0.5 meq / 100 g or less. The CEC of the silica particles A is measured, for example, in accordance with the method described in "Soil Environmental Analysis Method" (Soil Environmental Analysis Method Editorial Committee, 1997). The CEC of the silica particles A can be measured, for example, by the indophenol method after extraction by the modified Schollenberger method.

[0040] The silica particles A may be almost insoluble in water or may be insoluble in water. Despite being almost insoluble or insoluble in water, the silica particles A can achieve a higher growth-promoting effect than silicic acid or the like used as a plant growth promoter. Furthermore, despite being almost insoluble or insoluble in water, the silica particles A can improve the growth of plants that require silicon for growth. Therefore, it is presumed that the growth-promoting effect of the silica particles A is not due to the above-mentioned absorption of silicic acid. Furthermore, the silica particles A also have the effect of suppressing insect damage to plants. Although the reasons for these effects are not clear, it is presumed that the silica particles A activate specific useful microorganisms present in the soil.

[0041] The content of available silicic acid in silica particles A may be, for example, 100 mg / 100 g or less, preferably 80 mg / 100 g or less, more preferably 50 mg / 100 g or less, even more preferably 30 mg / 100 g or less, and may even be 0 mg / 100 g. When the content of available silicic acid in silica particles A is within the above range, they tend to be insoluble in water. The content of available silicic acid in silica particles A is measured, for example, in accordance with the method described in "Soil, Water Quality and Plant Analysis Method" (Japan Soil Association, 2001). The content of available silicic acid in silica particles A can be measured, for example, by the molybdenum blue method after extraction with a pH 6.2 phosphoric acid extract.

[0042] The silica particles A can be produced, for example, by using commercially available silica particles. The method for producing the silica particles A can be, for example, a production method (hereinafter also referred to as production method S) for producing the silica particles A using silica particles produced in the manufacturing process of electronic components, which will be described below.

[0043] FIG. 3 is an explanatory diagram illustrating an example of a method for producing silica particles A.

[0044] First, in forming the element body, in the laminate preparation step S11, a laminate, which is a rectangular parallelepiped element body, is prepared. For example, first, a plurality of ceramic sheets that will become the element body are prepared. The ceramic sheets may be thin plate-shaped. A conductive paste that will become electrodes and wiring is laminated on the ceramic sheets. A ceramic sheet that will become the element body is laminated on the laminated conductive paste. In this way, the ceramic sheets and the conductive paste are laminated. Then, by cutting to a predetermined size, an unfired laminate is formed. Thereafter, the unfired laminate is fired at a high temperature to prepare the laminate.

[0045] Next, a solvent introduction step S12 is performed. In the solvent introduction step S12, a solvent is introduced into the reaction vessel. The solvent may be any liquid that can disperse the metal alkoxide appropriately, such as 2-propanol.

[0046] Next, a catalyst introduction step S13 is performed. In the catalyst introduction step S13, first, stirring of the solvent in the reaction vessel is started. Then, ammonia water is introduced into the reaction vessel as an aqueous solution containing a catalyst. The catalyst is a hydroxide ion, and functions as a catalyst for promoting the hydrolysis of the metal alkoxide, which will be described later.

[0047] Next, an object introduction step S14 is performed. In the object introduction step S14, a plurality of element bodies formed in advance in the laminate preparation step S11 described above are introduced into the reaction vessel as objects.

[0048] Next, a polymer introduction step S15 is performed. In the polymer introduction step S15, polyvinylpyrrolidone (PVP) is introduced into the reaction vessel as a polymer. As a result, the polymer introduced into the reaction vessel is adsorbed onto the outer surface of the element body.

[0049] Next, a metal alkoxide introduction step S16 is performed. In the metal alkoxide introduction step S16, liquid tetraethyl orthosilicate is introduced into the reaction vessel as the metal alkoxide. Note that tetraethyl orthosilicate is also called tetraethoxysilane.

[0050] Next, the film-forming step S17 is performed. In the film-forming step S17, the stirring of the solvent, which began in the solvent-feeding step S12 described above, is continued for a predetermined time after the metal alkoxide is fed into the reaction vessel in the metal alkoxide-feeding step S16. As a result, the metal alkoxide is hydrolyzed by the hydroxide ions serving as a catalyst. When the metal alkoxide is hydrolyzed, the hydrolyzed metal alkoxide adheres to the surface of the element body. Then, the metal alkoxides attached to the surface of the element body dehydrate and condense with each other to form a glass film. Therefore, in the film-forming step S17, a sol-like glass film is formed by a liquid-phase reaction in the reaction vessel. Furthermore, the dehydration and condensation reaction between the metal alkoxides also progresses in the solution. As a result, sol-like silica particles are produced as a by-product.

[0051] Next, an element removal step S18 is performed. In this step, the element is removed from the reaction vessel. The element is then dried and fired to obtain an electronic component having a glass film formed on the outer surface of the element.

[0052] Next, a recovery step S19 is performed. In the recovery step S19, silica particles present in the solution in the reaction vessel are recovered. Specifically, the solvent in the reaction vessel is evaporated to recover the silica particles remaining in the reaction vessel. As described above, this solution contains sol-like silica particles. Note that tetraethyl orthosilicate and polyvinylpyrrolidone adhere to the outer surfaces of the recovered silica particles.

[0053] Next, a drying step S20 is performed. In the drying step S20, the sol-state silica particles recovered in the recovery step S19 are dried. This removes most of the liquid components, such as 2-propanol and water, from the recovered sol-state silica particles. Through this drying step S20, base particles having a particle size of 100 nm or more are generated as silica particles. The median particle size of the generated base particles is 120 nm or more and 800 nm or less in the particle size distribution of the base particles. The particle size of the generated base particles can be controlled, for example, by adjusting the time of the film-forming step S17.

[0054] Next, the baking step S21 is performed. In the baking step S21, the silica particles that have undergone the drying step S20 are baked at a temperature of 300°C to 450°C for 5 to 40 minutes. Specifically, the baking is performed at a temperature of 400°C for 30 minutes. As a result, the gel-like silica particles contained in the solution harden as the moisture and polymer evaporate. Through this baking step S21, fine particles with a particle size of less than 100 nm are generated as silica particles. The median particle size of the generated fine particles is 10 nm to 100 nm in the particle size distribution of the fine particles. Furthermore, the generated fine particles that are in contact with the base particles are sintered together with the base particles during the baking step S21. Therefore, the fine particles adhere to the surface of the base particles. The particle size of the generated silica fine particles can be controlled by adjusting the baking temperature and time in the baking step S21. In this manner, silica particles A are produced, which include base particles having a median particle size of 120 nm or more and 800 nm or less and fine particles having a median particle size of 10 nm or more and less than 100 nm.

[0055] As described above, the silica particles A can be produced using a solution containing silica particles, which is an industrial by-product. This eliminates the need to dispose of the solution containing silica particles. Furthermore, the energy consumed for the disposal can be reduced, which is environmentally friendly.

[0056] The silica particles A may be produced during the process of forming a glass film on an object, and may not be produced during the process of manufacturing an electronic component. In other words, the object introduced into the reaction vessel in the object introduction step S14 does not have to be an element body of an electronic component.

[0057] The solvent introduction step S12 may be performed after the catalyst introduction step S13 or the object introduction step S14. The solvent introduction step S12 may be performed before at least one of the metal alkoxide introduction step S16 and the catalyst introduction step S13. The solvent introduction step S12 may also be omitted. In this case, for example, if the amount of water contained in the aqueous solution containing the catalyst is appropriately large, the metal alkoxide will react in the liquid phase. Alternatively, the aqueous solution containing the catalyst may be introduced in a state where it is mixed with an organic solvent as a solvent.

[0058] Although the catalyst has been described as being added as an aqueous solution containing the catalyst, a solid compound containing the catalyst and water may be added separately to the reaction vessel, in which case the catalyst can be considered to have been added to the reaction vessel when it is produced in the reaction vessel. Alternatively, for example, a solid compound containing the catalyst may be added to the reaction vessel, and moisture in the air may be used as the water required for hydrolysis.

[0059] The object introduction step S14 may be performed before the catalyst introduction step S13. Furthermore, when the object introduction step S14 is performed before the catalyst introduction step S13, the metal alkoxide introduction step S16 may be performed before the catalyst introduction step S13 or the object introduction step S14. The object introduction step S14 may be performed before at least one of the metal alkoxide introduction step S16 and the catalyst introduction step S13.

[0060] In the metal alkoxide introduction step S16, the metal alkoxide may be generated in the reaction vessel, instead of being introduced into the reaction vessel after being generated outside the reaction vessel. For example, the metal alkoxide may be generated by reacting a metal salt with an alcohol. Therefore, even when a metal salt and an alcohol, which are metal alkoxide precursors, are introduced into the reaction vessel and reacted to generate the metal alkoxide, the metal alkoxide can be considered to have been introduced into the reaction vessel.

[0061] The metal alkoxide is not limited to tetraethyl orthosilicate. The alkoxy group of the metal alkoxide may be a methoxy group, a propoxy group, or the like, or may be modified with a functional group such as a long-chain alkyl group or an epoxy group, as in a coupling agent. Furthermore, the coordination number for the metal contained in the metal alkoxide is not limited to tetracoordination, but may be 3 or 2.

[0062] The element removal step S18 may be omitted. That is, the recovery step S19 may be performed while the element remains in the reaction vessel.

[0063] In the calcination step S21, the temperature at which the sol- or gel-like particles are calcined may be less than 300° C. or more than 450° C. The calcination time may be less than 5 minutes or more than 40 minutes. For example, even if the temperature is higher than 450° C., calcination for less than 5 minutes may be sufficient as long as silica particles having a median particle size of 120 nm to 800 nm can be produced.

[0064] In the recovery step S19, the silica particles may be recovered by, for example, evaporating the solvent by drying under reduced pressure. The particle size of the base particles of the silica particles generated in the drying step S20 and the firing step S21 may be controlled by the concentration of the materials in each step.

[0065] The base particles of silica particles A may be multilayer particles having a core portion and an outer layer. Base particles that are multilayer particles are also referred to as multilayer base particles. The core portion is approximately spherical and includes the center of gravity of the silica particle A. The core portion may have an internal void. The outer layer is a portion that covers the core portion from the outside and includes the outer surface of the base particle. The base particle has an outer layer on the surface side including the outer surface. The silica particles A may contain polyvinylpyrrolidone. When the silica particles A contain polyvinylpyrrolidone, the outer layer may contain polyvinylpyrrolidone. When the outer layer contains polyvinylpyrrolidone, the concentration of polyvinylpyrrolidone is higher than the concentration of polyvinylpyrrolidone in the portion of the silica particles A excluding the outer layer, i.e., the core portion. Furthermore, when the silica particles A are imaged using, for example, a field emission transmission electron microscope (FE-TEM), a substantially clear interface may be observed between the outer layer and the portion excluding the outer layer. The multilayer base particle may or may not contain fine particles.

[0066] The ratio of the thickness T of the outer layer to the particle diameter D of the base particles (also referred to as the T / D ratio) may be, for example, 2% or more. For example, when the particle diameter D of the base particles is approximately 260 nm and the thickness T of the outer layer is approximately 15 nm, the T / D ratio is approximately 5.8%. Polyvinylpyrrolidone has various properties, such as high hygroscopicity and viscosity increasing properties. Therefore, when the outer layer contains polyvinylpyrrolidone, it tends to be more effective in promoting plant growth, such as preventing soil from drying out and sustained release of active ingredients.

[0067] The thickness T of the outer layer is defined as follows. First, an image of the base particle is taken using an FE-TEM or the like. In the image, the dimension of the outer layer at an arbitrary point on the outer surface of the base particle in a direction perpendicular to the outer surface is defined as the thickness T of the outer layer at that point. More specifically, "the direction perpendicular to the outer surface at an arbitrary point on the outer surface of the base particle" refers to the direction perpendicular to a tangent line drawn to the base particle with the arbitrary point as the contact point. The thickness of the outer layer is the distance from the arbitrary point to the interface in the perpendicular direction.

[0068] The multilayer base particles are produced, for example, by recovering silica particles from the solution after carrying out the steps from the laminate preparation step S11 to the drying step S20 in the production method S. In other words, the multilayer base particles can be silica particles after carrying out the drying step S20 and before carrying out the firing step S21 in the production method S.

[0069] The concentration of polyvinylpyrrolidone in the outer layer of the silica particles A may be equal to or less than the concentration of polyvinylpyrrolidone in the core portion. The ratio of the thickness T of the outer layer to the particle diameter D of the silica particles A may be less than 2%. Even in these cases, the effects of the seedling container of the present disclosure can be obtained.

[0070] The base particles may have a T / D ratio of less than 2% or may not have an outer layer, i.e., the silica particles A may have no clear boundary between the core and the outer layer.

[0071] The silica particles A may include both base particles without a multilayer structure and multilayer base particles. In other words, the silica particles A may include both silica particles after the firing step S21 and silica particles after the drying step S20 that have not been subjected to the firing step S21.

[0072] The first seedling container may have a coating film containing silica particles formed on at least a portion of the surface.

[0073] The coating film containing silica particles may be formed, for example, by immersing the seedling container in a liquid composition containing silica particles and a dispersion medium, or by applying a liquid composition containing silica particles and a dispersion medium to the surface of the seedling container.

[0074] The dispersion medium in the liquid composition is not particularly limited as long as it is a component capable of dispersing silica particles, and may be water, an organic solvent such as alcohols, ethers, or ketones, a resin such as an acrylic resin, an epoxy resin, a urethane resin, or polyvinylpyrrolidone, or a mixture thereof.

[0075] The liquid composition may contain other components in addition to the above components, such as a spreading agent, a filler, a dispersant, a thickener, an antifoaming agent, a surfactant, a lubricant, and a soil conditioner.

[0076] The first seedling container may have silica particles supported on the surface thereof. When silica particles are supported on the surface, the soil and the silica particles come into direct contact with each other, which makes it easier to achieve the effect of improving plant growth.

[0077] The content of silica particles in the first seedling raising container can be adjusted appropriately depending on the volume of the seedling raising container, but may be, for example, 0.1 g or more, preferably 0.25 g or more, and more preferably 2.5 g or more per 1 L of the volume of the seedling raising container. The content of silica particles in the first seedling raising container may be, for example, 100 g or less per 1 L of the volume of the seedling raising container.

[0078] The material constituting the first seedling container is not particularly limited, but may be, for example, polyethylene, polypropylene, polystyrene, polyvinyl chloride, biodegradable resin, etc. Among these, it is preferable that the material contains biodegradable resin, from the viewpoint of being able to plant the seedling container in the ground.

[0079] Examples of biodegradable resins that may be used in the first seedling container include aliphatic polyester resins such as polylactic acid, polyhydroxyalkanoate, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), polycaprolactone, polybutylene succinate, polybutylene succinate adipate, polyethylene succinate, and polyglycolic acid; aliphatic-aromatic copolymer polyester resins such as polybutylene terephthalate / succinate, polyethylene terephthalate / succinate, and polybutylene adipate / terephthalate; and mixtures of natural polymers such as starch, cellulose, chitosan, gluten, gelatin, collagen, and keratin with the above-mentioned aliphatic polyester resins or aliphatic-aromatic copolymer polyester resins. One or more types of biodegradable resins may be used.

[0080] The first seedling container is preferably made of nonwoven fabric. By using a nonwoven fabric for the seedling container, the surface area can be increased, which can increase the contact area with the soil and the amount of silica particles supported.

[0081] The shape of the first seedling container is not particularly limited as long as it can be filled with soil to form a medium for growing plants, and may be, for example, a pot, a plug tray, a planter, or the like.

[0082] The first seedling container may contain other ingredients, such as a spreading agent, a filler, a dispersant, a thickener, an antifoaming agent, a surfactant, a lubricant, and a soil conditioner, as long as the effects of the seedling container of the present disclosure are obtained.

[0083] The first seedling container preferably further contains a spreading agent as another component. A spreading agent is a chemical that improves the adhesion, fixation, permeability, etc. of a chemical solution. By including a spreading agent, the adhesion of silica particles to the seedling container can be improved and the outflow of silica particles can be suppressed.

[0084] The first seedling container tends to improve the germination rate of plants, presumably because the silica particles in the seedling container activate beneficial microorganisms in the soil.

[0085] The first seedling raising container can be obtained, for example, by a method (Production Method 1-1) in which the seedling raising container is immersed in a liquid composition containing silica particles and then dried. Production Method 1-1 will be described below.

[0086] First, a liquid composition containing silica particles is prepared. The liquid composition can be, for example, a silica particle / PVP dispersion obtained by mixing silica particles with an aqueous PVP solution. The silica particle / PVP dispersion is preferably prepared using an ultrasonic disperser. The content of the silica particles in the liquid composition, calculated as solid content, can be 50% by mass or less, 1% by mass or more and 30% by mass or less, or 1% by mass or more and 10% by mass or less.

[0087] Next, the seedling container is immersed in the liquid composition. After a predetermined time has passed, the seedling container is removed from the liquid composition and dried. The drying may be performed, for example, at a temperature of 80°C for 30 minutes. In this manner, a first seedling container containing silica particles is produced. The first seedling container may further contain PVP.

[0088] The first seedling raising container can be obtained, for example, by a method (Production Method 1-2) in which a liquid composition containing silica particles is applied to the surface of the seedling raising container. Production Method 1-2 will be described below.

[0089] First, a liquid composition containing silica particles is prepared. The liquid composition can be, for example, a silica particle / PVP dispersion obtained by mixing silica particles with an aqueous PVP solution. The silica particle / PVP dispersion is preferably prepared using an ultrasonic disperser. The content of the silica particles in the liquid composition, calculated as solid content, can be 50% by mass or less, 1% by mass or more and 30% by mass or less, or 1% by mass or more and 10% by mass or less.

[0090] Next, the liquid composition is applied to the surface of a seedling container and dried. Drying may be performed, for example, at a temperature of 80°C for 30 minutes. In this way, a first seedling container containing silica particles is produced. The first seedling container may further contain PVP.

[0091] The content of silica particles in the first seedling raising container can be controlled by the content of silica particles in the liquid composition, the immersion time in the liquid composition, the thickness of the coating film, and the like.

[0092] The liquid composition in the 1-1 production method and the 1-2 production method can be a solution in which sol-like silica particles are produced as a by-product in the film-forming step S17 in the above-mentioned silica particle production method S. When the first seedling container is produced using the solution, the produced seedling container may be fired. The firing may be performed, for example, at 400°C for 30 minutes.

[0093] The liquid composition in Production Method 1-1 and Production Method 1-2 can be used for purposes other than the production of seedling containers No. 1. For example, the liquid composition can be directly injected or sprayed into the ground. The liquid composition can also be dripped into the ground continuously or intermittently.

[0094] Second Embodiment A seedling raising container according to a second embodiment (hereinafter also referred to as a second seedling raising container) further contains a biocarbon material.

[0095] The second seedling container contains silica particles. The silica particles include silica base particles having a particle size of 100 nm or more. The median particle size of the base particles is 120 nm or more and 800 nm or less in the particle size distribution of the base particles. The same description of the silica particles in the first embodiment applies to the silica particles.

[0096] The content of silica particles in the second seedling raising container can be adjusted appropriately depending on the volume of the seedling raising container, but may be, for example, 0.1 g or more, preferably 0.25 g or more, and more preferably 2.5 g or more per 1 L of the volume of the seedling raising container. The content of silica particles in the second seedling raising container may be, for example, 100 g or less per 1 L of the volume of the seedling raising container.

[0097] The biocarbon material can be, for example, a char produced by heating a biomass material in an environment with a low oxygen concentration. The biomass material can be a material of biological origin, such as rice husks, bamboo, wood, rice straw, livestock manure, or paper sludge discharged during the production of recycled paper. The biocarbon material can be, for example, a char of at least one material selected from the group consisting of rice husks, bamboo, and wood.

[0098] The biocarbon material may be in the form of a powdered char produced by finely crushing the raw material, or may be used in the form of a char produced from coarsely crushed raw material.

[0099] The second seedling container may be made by molding a powdered or coarsely pulverized biocarbon material into a container shape. To maintain the container shape, a binder or the like may be used.

[0100] The second seedling container preferably contains a biocarbon material as a main component, which allows the second seedling container to be planted in the ground.

[0101] The second seedling container tends to improve the germination rate of plants, presumably because the silica particles in the seedling container activate beneficial microorganisms in the soil.

[0102] The second seedling container can be obtained by, for example, the above-mentioned manufacturing method 1-1. The description of the first embodiment is applied to the manufacturing method 1-1.

[0103] In manufacturing the second seedling container, a solution in which sol-like silica particles are produced as a by-product in the film-forming step S17 in the above-mentioned method for manufacturing silica particles S can be used. Specifically, a seedling container containing a biocarbon material is immersed in the solution, and then the drying step S20 and the firing step S21 in the method for manufacturing silica particles S are performed, thereby manufacturing the second seedling container containing silica particles and a biocarbon material.

[0104] Third Embodiment

[0105] The seedling raising container according to the third embodiment (hereinafter also referred to as the third seedling raising container) further contains a fatty acid alkali salt.

[0106] The third seedling container contains silica particles. The silica particles include silica base particles having a particle size of 100 nm or more. The median particle size of the base particles is 120 nm or more and 800 nm or less in the particle size distribution of the base particles. The same description of the silica particles in the first embodiment applies to the silica particles.

[0107] The content of the silica particles in the third seedling raising container can be adjusted appropriately depending on the volume of the seedling raising container, but may be, for example, 0.1 g or more, preferably 0.25 g or more, and more preferably 2.5 g or more per 1 L of the volume of the seedling raising container. The content of the silica particles in the third seedling raising container may be, for example, 100 g or less per 1 L of the volume of the seedling raising container.

[0108] The fatty acid alkali salt is a reaction product of a fatty acid and an alkali metal hydroxide. Examples of the fatty acid alkali salt include a fatty acid lithium salt, a fatty acid sodium salt, a fatty acid potassium salt, and a fatty acid rubidium salt, and the fatty acid sodium salt is preferred.

[0109] The fatty acid constituting the fatty acid alkali salt is not particularly limited. The number of carbon atoms of the fatty acid constituting the fatty acid alkali salt may be from 2 to 30, and preferably from 12 to 18. Examples of fatty acids constituting the fatty acid alkali salt include hexanoic acid, octanoic acid, decanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, eicosanoic acid, oleic acid, linoleic acid, and linolenic acid.

[0110] The third seedling container preferably contains a water-soluble fatty acid alkali salt, more preferably contains a water-soluble fatty acid alkali salt as a main component, thereby allowing the third seedling container to be planted in the ground together with the seedling container.

[0111] The third seedling container tends to improve the germination rate of plants, presumably because the silica particles in the seedling container activate beneficial microorganisms in the soil.

[0112] The third seedling raising container can be produced, for example, by utilizing a reaction between a fatty acid and an alkali metal hydroxide (third production method). The third production method will be described below.

[0113] First, a liquid composition containing silica particles is prepared. The liquid composition can be, for example, a silica particle / PVP dispersion obtained by mixing silica particles with an aqueous PVP solution. The silica particle / PVP dispersion is preferably prepared using an ultrasonic disperser. The content of the silica particles in the liquid composition, calculated as solid content, can be 50% by mass or less, 1% by mass or more and 30% by mass or less, or 1% by mass or more and 10% by mass or less.

[0114] Next, the fatty acid and alkali metal hydroxide are mixed into the liquid composition and reacted. After the predetermined viscosity is reached, the reaction liquid is poured into a mold and dried. In this way, a solid fatty acid alkali salt containing silica particles is obtained.

[0115] The fatty acid alkali salt is then removed from the mold and molded into a desired shape to produce a third seedling container containing silica particles and a fatty acid alkali salt. The third seedling container may further contain PVP.

[0116] The liquid composition in the third production method can be a solution in which sol-like silica particles are produced as a by-product in the film-forming step S17 in the above-described method S for producing silica particles.

[0117] In the third production method, the fatty acid alkali salt is not limited to a reaction product of a fatty acid and an alkali metal hydroxide, but may be a reaction product of a fatty acid ester and an alkali metal hydroxide, and the fatty acid ester may be a fatty acid methyl ester, a fatty acid glycerin ester, or the like.

[0118] Fourth Embodiment A liquid composition according to a fourth embodiment includes silica particles and a solvent. The silica particles include silica base particles having a particle size of 100 nm or more. The median particle size of the base particles is 120 nm or more and 800 nm or less in the particle size distribution of the base particles. The same description of the silica particles in the first embodiment applies to the silica particles.

[0119] The solvent in the liquid composition is not particularly limited as long as it is a dispersion medium capable of dispersing silica particles, and may be water, an organic solvent such as alcohols, ethers, or ketones, a resin such as an acrylic resin, an epoxy resin, a urethane resin, or polyvinylpyrrolidone, or a mixture thereof.

[0120] The content of silica particles in the liquid composition may be 50% by mass or less, 1% by mass or more and 30% by mass or less, or 1% by mass or more and 10% by mass or less, in terms of solid content.

[0121] The liquid composition may contain other components in addition to the above components, such as a spreading agent, a filler, a dispersant, a thickener, an antifoaming agent, a surfactant, a lubricant, and a soil conditioner.

[0122] The liquid composition preferably further contains a spreading agent as another component, which makes it easier for the silica particles to remain in the ground and can prevent the silica particles from flowing out.

[0123] The liquid composition of this embodiment can be suitably used for plant growth. By injecting or spraying the liquid composition into soil, plant growth can be improved. This is presumably because the silica particles in the liquid composition activate beneficial microorganisms in the soil. The liquid composition can also be drip-fed so that it is injected into the ground continuously or intermittently.

[0124] The liquid composition of this embodiment can also be used as a coating agent. A coating film (also referred to as a growth-improving coating film) having the function of improving plant growth is formed on a surface coated with the liquid composition. For example, by coating at least a portion of the inner surface of a seedling container with the liquid composition, a seedling container having a growth-improving coating film formed thereon can be produced. Furthermore, for example, by coating at least a portion of the surface of a plant seed with the liquid composition, seeds having a growth-improving coating film formed thereon can be produced. By growing plants using these seedling containers or seeds, it tends to be easier to obtain an effect of improving germination rate and an effect of promoting growth.

[0125] The liquid composition of this embodiment can be a solution in which sol-like silica particles are produced as a by-product in the film-forming step S17 of the method S for producing silica particles described above.

[0126] Hereinafter, the present disclosure will be described in more detail with reference to examples and comparative examples, but the present disclosure is not limited to these.

[0127] [Production of Silica Particles] A plurality of laminates each consisting of a plurality of ceramic sheets were prepared. 2-Propanol was added as a solvent to a reaction vessel, and stirring was initiated. Next, ammonia water, the plurality of laminates, polyvinylpyrrolidone, and tetraethoxysilane were added, in that order, to the reaction vessel. After a predetermined time had elapsed, the plurality of laminates were removed. Sol-state silica particles were recovered by evaporating the solvent from the solution in the reaction vessel. The recovered sol-state silica particles were further dried and then fired at 400°C for 30 minutes to obtain silica particles.

[0128] FIG. 1 is an image of silica particles observed with an SEM at a magnification of 50,000 times. FIG. 2 is an image of silica particles observed with an SEM at a magnification of 250,000 times. The silica particles contained mother particles and microparticles, with a plurality of microparticles attached to the outer surfaces of the mother particles. The median particle size of the mother particles was 251 nm in the particle size distribution of the mother particles. The median particle size of the microparticles was 16 nm. The particle size distributions of the mother particles and microparticles were determined as follows in the SEM images of the silica particles observed at 50,000 times and 200,000 times. First, the particle size distribution was determined from the longest diameters measured for 25 or more mother particles and microparticles in each SEM image. Next, the median values ​​of the determined particle size distributions were determined as the median particle sizes of the mother particles and microparticles. The crystallinity of the silica particles was confirmed to be amorphous by X-ray diffraction (XRD).

[0129] The specific surface area of ​​the obtained silica particles measured by the BET method is 163 m ２ The specific surface area of ​​the particles after drying and before calcination was 18.3 m2 by the BET method. ２ / g.

[0130] Silica particles were immersed in a strong alkaline solution for 5 days, and the surfaces or cross sections of the silica particles removed from the alkaline solution were observed using an SEM. The presence of multiple primary particle boundaries was confirmed in the mother particles and fine particles of the silica particles. The sizes of two of the multiple primary particles were measured in the SEM observation image and were found to be 26 nm and 29 nm.

[0131] The results of component analysis of the silica particles were as follows: No heavy metals (arsenic, lead, cadmium, mercury, chromium, cyanide) were detected in the silica particles. ２ : More than 99% by mass (X-ray fluorescence analysis) C: 1.5% by mass (CS meter) N: 0.73% by mass (inert gas fusion method) P ２ O ５ : 0.01 mass% (X-ray fluorescence analysis) SO ３ : 0.04% by mass (X-ray fluorescence analysis) Cl: 0.02% by mass (X-ray fluorescence analysis) Na: less than 0.01% by mass (emission spectroscopy) CEC: 0.5 meq / 100 g (indophenol method) Nitrate nitrogen: 0.0 mg / 100 g (diazo dye method) Ammonia nitrogen: 1.5 mg / 100 g (indophenol method) Available silicic acid: 25.8 mg / 100 g (molybdenum blue method)

[0132] Example 1 The silica particles were mixed with an aqueous PVP solution and dispersed using an ultrasonic disperser to prepare a silica particle / PVP dispersion with a silica particle solids concentration of 10% by mass. A seedling pot (made of biodegradable nonwoven fabric, 4 cm x 4 cm x 4.9 cm) was immersed in the dispersion. The seedling pot removed from the dispersion was dried at 80°C for 30 minutes to obtain a seedling pot carrying silica particles and PVP. Seventy-two seedling pots were produced using the above procedure. The average mass of the seedling pots was measured.

[0133] Separately from the above, one seedling pot (made of biodegradable nonwoven fabric, 4 cm × 4 cm × 4.9 cm) was immersed in an aqueous PVP solution. The seedling pot was removed from the aqueous PVP solution and dried at 80°C for 30 minutes to obtain a seedling pot carrying PVP. The mass of the seedling pot was measured.

[0134] The average amount of silica supported was calculated by subtracting the mass of the seedling pot supported with PVP from the average mass of the seedling pots supported with silica and PVP. The amount of silica particles supported in the seedling pot of Example 1 was 0.02 g.

[0135] Next, soil (manufactured by Togawa Heiwa Farm Co., Ltd.) made from a mixture of Akadama soil, Kanuma soil, compost, and cocoyuki was poured into the seedling pots containing silica particles and PVP, with the surface tapped to remove air. A hole 2 cm deep was drilled from the surface, and two spinach seeds were poured in. The soil was replaced, and 1 L of water was sprayed to initiate growth.

[0136] (Examples 2 and 3) Spinach was grown in the same manner as in Example 1, except that seedling pots with the silica loading amounts shown in Table 1 were obtained by adjusting the content of silica particles in the silica particle / PVP dispersion and the immersion time in the dispersion.

[0137] Comparative Example 1 Spinach was grown in the same manner as in Example 1, except that seedling pots (made of biodegradable nonwoven fabric, 4 cm x 4 cm x 4.9 cm) not carrying silica particles were used.

[0138] For each of Examples 1 to 3 and Comparative Example 1, 72 seedling pots were used for growth, and the germination rate was evaluated at predetermined intervals. The results are shown in Table 1.

[0139]

[0140] In Examples 1 to 3, which used seedling pots carrying silica particles, the germination rate was significantly improved compared to Comparative Example 1, which used seedling pots not carrying silica particles. Furthermore, the germination rate tended to improve as the amount of silica particles carried by the seedling pot increased.

[0141] In the above-described embodiments, configurations that can be combined may be combined with each other.

[0142] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0143] It will be appreciated by those skilled in the art that the exemplary embodiments described above are examples of the following aspects.

[0144] (Item 1) A seedling container according to one embodiment of the present disclosure contains silica particles. The silica particles contain silica base particles having a particle size of 100 nm or more. The median particle size of the silica base particles is 120 nm or more and 800 nm or less in the particle size distribution of the silica base particles. (Item 2) The seedling container according to item 1 further contains silica fine particles having a particle size of less than 100 nm. The median particle size of the silica fine particles is 10 nm or more and 100 nm or less in the particle size distribution of the silica fine particles. (Item 3) The seedling container according to items 1 or 2 further contains a biodegradable resin. (Item 4) The seedling container according to any one of items 1 to 3 further contains a biocarbon material. (Item 5) The seedling container according to any one of items 1 to 4 further contains a fatty acid alkali salt. (Item 6) A liquid composition according to another embodiment of the present disclosure contains silica particles and a solvent. The silica particles contain silica base particles having a particle size of 100 nm or more. The median particle size of the silica base particles is 120 nm or more and 800 nm or less in the particle size distribution of the silica base particles.

[0145] S11: laminate preparation step, S12: solvent introduction step, S13: catalyst introduction step, S14: object introduction step, S15: polymer introduction step, S16: metal alkoxide introduction step, S17: film formation step, S18: element removal step, S19: recovery step, S20: drying step, S21: firing step.

Claims

1. A seedling container comprising silica particles, the silica particles comprising silica base particles having a particle size of 100 nm or more, and a median particle size of the silica base particles being 120 nm or more and 800 nm or less in the particle size distribution of the silica base particles.

2. The seedling container according to claim 1, wherein the silica particles further comprise silica microparticles having a particle size of less than 100 nm, and the median particle size of the silica microparticles is 10 nm or more and 100 nm or less in the particle size distribution of the silica microparticles.

3. The seedling container according to claim 1 or 2, further comprising a biodegradable resin.

4. The seedling container according to any one of claims 1 to 3, further comprising a biocarbon material.

5. The seedling container according to any one of claims 1 to 4, further comprising a fatty acid alkali salt.

6. A liquid composition comprising silica particles and a solvent, wherein the silica particles comprise silica base particles having a particle size of 100 nm or more, and the median particle size of the silica base particles is 120 nm or more and 800 nm or less in the particle size distribution of the silica base particles.

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