JP2014079243A - Artificial soil particles and artificial soil aggregates - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide artificial soil particles that demonstrate a well-balanced basic performance of soil, are of high quality and are easy to handle.SOLUTION: Artificial soil particles 10 are formed by the aggregation of multiple fillers 1 having subnanometer-order-to-submicrometer-order pores 2, and submicrometer-order-to-submillimeter-order communication holes 3 are formed between the fillers 1. The communication holes 3 capture moisture W and nutrients K, N, P from the outside, and the pores 2 are dispersed around the communication holes 3 in such a manner as to be able to receive the nutrients K, N, P from the communication holes 3. The fillers 1 are connected in a three-dimensional network shape in such a manner that the total volume of the communication holes 3 is larger than the total volume of the pores 2.

Description

  The present invention relates to artificial soil particles in which a plurality of fillers are aggregated, and an artificial soil aggregate obtained by aggregating the artificial soil particles.

  In recent years, plant factories that grow plants such as vegetables in an environment where growth conditions are controlled are increasing. Conventional plant factories mainly focused on hydroponic cultivation of leafy vegetables such as lettuce, but recently there is a movement to try cultivation of root vegetables that are not suitable for hydroponic cultivation in plant factories. In order to cultivate root vegetables in a plant factory, it is necessary to develop artificial soil that is excellent in basic performance as a soil, high in quality, and easy to handle.

  As artificial soil developed so far, there has been aggregated structure zeolite in which powdery zeolite is aggregated by binding with a binder made of a water-soluble polymer (see, for example, Patent Document 1). The aggregated structure zeolite of Patent Document 1 is obtained by aggregating zeolite to improve water retention in order to use the porous structure and cation exchange capacity of zeolite with poor water retention as artificial soil.

  A porous body having an open cell structure based on an organic polymer material has also been developed (see, for example, Patent Document 2). The open-cell porous body of Patent Document 2 is produced by thermally fusing a powdered thermoplastic resin, a binder component, and a surfactant, and has a low-density and open-cell structure. Therefore, it is said that it is easy to show good liquid absorbency. This document describes that this open-cell porous body can be used as a plant culture medium.

JP 2000-336356 A (refer to claim 1 in particular) JP 2011-241262 A (refer to paragraphs 0050 to 0052 in particular)

  In the development of artificial soil, for example, a control function capable of appropriately supplying water and nutrients to the plant to be cultivated is required while achieving plant growth ability equivalent to that of natural soil. That is, the artificial soil is required to exhibit the basic performance as a soil in a well-balanced manner.

  In this regard, the aggregate structure zeolite of Patent Document 1 is obtained by simply mixing and drying a powdered zeolite and a binder in the presence of water. It cannot be said that the structure is acting effectively, and the performance of zeolite is not always exhibited sufficiently. In addition, zeolite is likely to become lumpy during the production of aggregates, and water retention is not always sufficiently enhanced. Water retention, which is one of the basic performances of soil, affects fertilizer retention, so if the water retention capacity of aggregates cannot be sufficiently increased, the porous structure and positive polarity of zeolite related to fertilizer retention It is also difficult to effectively use the ion exchange capacity as artificial soil.

  The open-cell porous body of Patent Document 2 is obtained by pulverizing a foam of a thermoplastic resin to obtain a raw material powder, and this powder is thermally fused to form a porous body having water absorption. ing. However, since the thermoplastic resin used in Patent Document 2 does not have fertilizer per se, when the generated open-cell porous material is used as artificial soil, the basic performance as soil is well balanced. It cannot be said that it can be demonstrated.

  The present invention has been made in view of the above-mentioned problems, and is capable of exhibiting the basic performance as a well-balanced, high-quality and easy-to-handle artificial soil, that is, artificial soil particles and artificial soil obtained by aggregating them. The purpose is to provide aggregates.

The characteristic configuration of the artificial soil particles according to the present invention for solving the above problems is as follows:
Artificial soil particles in which a plurality of fillers having pores on the order of sub-nm to sub-μm are assembled,
A communication hole in the order of sub μm to sub mm is formed between the fillers,
The pores are dispersedly arranged around the communication holes so that the communication holes take in moisture and nutrients from the outside and the pores can receive the nutrients from the communication holes.

According to the artificial soil particle of this configuration, since the pore diameter of the pores of the filler is on the order of sub-nm to sub-μm, it is possible to effectively incorporate nutrients necessary for improving the quality of plants into the pores. it can. Moreover, since the hole diameter of the communicating hole formed between the aggregated fillers is on the order of sub-μm to sub-mm, moisture essential for the growth of plants can be effectively absorbed into the communicating hole. In addition, with regard to the positional relationship between the pores and the communication holes, the pores are distributed around the communication holes so that the communication holes take in moisture and nutrients from the outside and the pores can receive nutrients from the communication holes. Therefore, mainly the pores can be provided with fertilizer and the communication holes can be provided with water retention.
As described above, the artificial soil particles of this configuration have a specific relationship between the pores and the communication holes in one particle, and share different functions between the pores and the communication holes. Therefore, it is possible to realize high-quality and functional artificial soil particles that can exhibit the basic performance of the soil in a well-balanced manner (that is, excellent balance between water retention and fertilizer retention). In addition, since such artificial soil particles can appropriately supply moisture and nutrients to the plant to be cultivated, maintenance is not required and handling is easy.

In the artificial soil particles according to the present invention,
The filler is preferably combined in a three-dimensional network so that the total volume of the communication hole is larger than the total volume of the pore.

  According to the artificial soil particle of this structure, since the filler is combined in a three-dimensional network, the structure of the artificial soil particle is stabilized. In addition, since the total volume of the communication holes in the coupled state is larger than the total volume of the pores, the artificial soil particles can be reduced in weight and can be handled easily.

In the artificial soil particles according to the present invention,
It is preferable that a water retention material is introduced into at least a part of the communication hole and that the ion exchange ability is imparted to the pore.

  According to the artificial soil particle of this structure, the water retention property of a communicating hole further increases by introduce | transducing a water retaining material into at least one part of a communicating hole. Moreover, the fertilizer of a pore improves further by providing ion exchange ability to a pore. As a result, artificial soil particles that can withstand long-term use can be realized.

In the artificial soil particles according to the present invention,
It is preferable that the pore diameter is 0.2 to 800 nm, and the communication hole diameter is 0.1 to 500 μm.

  According to the artificial soil particles of this configuration, the pore diameter is 0.2 to 800 nm, and the pore diameter of the communication hole is 0.1 to 500 μm. Sufficient moisture can be retained. As a result, artificial soil particles that can withstand long-term use can be realized.

In the artificial soil particles according to the present invention,
It preferably has a particle size of 0.2 to 10 mm.

  According to the artificial soil particle of this structure, it can be set as the artificial soil which is easy to handle especially suitable for cultivation of root vegetables by making a particle size into 0.2-10 mm.

The characteristic configuration of the artificial soil aggregate according to the present invention for solving the above problems is as follows.
The artificial soil particles according to any one of the above are aggregated.

  According to the artificial soil aggregate of this configuration, since the artificial soil particles of the present invention are agglomerated, the basic performance as soil can be exerted in a well-balanced manner (that is, in balance between water retention and fertilizer retention). Excellent), high quality and functional artificial soil aggregate can be realized. Moreover, since such an artificial soil aggregate can supply a water | moisture content and a nutrient appropriately with respect to the plant of cultivation object, it does not take a maintenance effort and becomes easy to handle.

FIG. 1 is an explanatory diagram conceptually showing the artificial soil particles of the present invention. FIG. 2 is a model diagram conceptually showing the positional relationship between the pores and the communicating holes of the artificial soil particles of the present invention. FIG. 3 is a schematic diagram of the artificial soil aggregate of the present invention. FIG. 4 is a graph showing the measurement results of the pore size distribution of the artificial soil particles or artificial soil aggregates of the present invention by mercury porosimetry.

  Hereinafter, the embodiment regarding the artificial soil particle which concerns on this invention, and the artificial soil aggregate is described based on FIGS. However, the present invention is not intended to be limited to the configurations described in the embodiments and drawings described below.

<Configuration of artificial soil particles>
FIG. 1 is an explanatory view conceptually showing an artificial soil particle 10 of the present invention. FIG. 1A illustrates an artificial soil particle 10 using a zeolite 1a, which is a porous natural mineral, as the filler 1. FIG. 1B illustrates an artificial soil particle 10 using a hydrotalcite 1 b that is a layered natural mineral as the filler 1. Note that the symbols x, y, and z shown in FIG. 1 represent the sizes of the pore 2, the communication hole 3, and the artificial soil particle 10 described later, respectively, but the sizes of x, y, and z on the drawing. Does not reflect the actual size.

  The artificial soil particle 10 is a granular material in which a plurality of fillers 1 are aggregated. It is not essential that the fillers 1 in the artificial soil particles 10 are in contact with each other, and if a relative positional relationship within a certain range is maintained through a binder or the like in one particle, It can be considered that a plurality of fillers 1 are aggregated to form a granular shape. The filler 1 constituting the artificial soil particle 10 has a large number of pores 2 from the surface to the inside. The pore 2 includes various forms. For example, when the filler 1 is the zeolite 1a shown in FIG. 1 (a), the voids 2a existing in the crystal structure of the zeolite 1a are the pores 2, and the hydrotalcite 1b shown in FIG. 1 (b) The interlayer 2b existing in the layer structure of the hydrotalcite 1b is the pore 2. That is, in the present invention, “pores” mean voids, interlayers, spaces, etc. existing in the structure of the filler 1, and these are not limited to “pore-like” forms.

  The size of the pores 2 of the filler 1 (the average value of the size x of the void 2a or the interlayer 2b shown in FIG. 1) is on the order of sub-nm to sub-μm. For example, the size of the pores 2 can be set to about 0.2 to 800 nm, but when the filler 1 is the zeolite 1a shown in FIG. 1 (a), the void 2a present in the crystal structure of the zeolite 1a. The size (diameter) is about 0.3 to 1.3 nm. When the filler 1 is the hydrotalcite 1b shown in FIG.1 (b), the size (distance) of the interlayer 2b which exists in the layer structure of the said hydrotalcite 1b is about 0.3-3.0 nm. In addition, the organic porous material mentioned later can also be used as the filler 1, and the diameter x of the pore 2 in that case is about 0.1 to 0.8 μm. The size of the pores 2 of the filler 1 is optimal using a gas adsorption method, a mercury intrusion method, a small-angle X-ray scattering method, an image processing method, or a combination of these methods depending on the state of the object to be measured. Measured by the method.

  As the filler 1, it is preferable to use a material in which the pores 2 have an ion exchange capacity so that the artificial soil particles 10 have a sufficient fertilizer. In this case, as the material imparted with ion exchange ability, a material imparted with cation exchange ability, a material imparted with anion exchange ability, or a mixture of both can be used. Separately, prepare a porous material that does not have ion exchange capacity (for example, polymer foam, glass foam, etc.), and press-fit the material with the above ion exchange capacity into the pores of the porous material. It is also possible to introduce it by impregnation or the like and use it as the filler 1. Examples of the material imparted with the cation exchange ability include cation exchange minerals, humus, and cation exchange resins. Examples of the material imparted with the anion exchange ability include anion exchange minerals and anion exchange resins.

  Examples of cation exchange minerals include smectite minerals such as montmorillonite, bentonite, beidellite, hectorite, saponite, and stevensite, mica minerals, vermiculite, and zeolite. Examples of the cation exchange resin include a weak acid cation exchange resin and a strong acid cation exchange resin. Among these, the zeolite or bentonite used in this embodiment is preferable. The cation exchange mineral and the cation exchange resin can be used in combination of two or more. The cation exchange capacity of the cation exchange mineral and the cation exchange resin is set to 10 to 700 meq / 100 cc, preferably 20 to 700 meq / 100 cc, more preferably 30 to 700 meq / 100 cc. When the cation exchange capacity is less than 10 meq / 100 cc, nutrients cannot be taken in sufficiently, and the taken-up nutrients may be lost early due to irrigation or the like. On the other hand, even if the fertilizer is excessively increased so that the cation exchange capacity exceeds 700 meq / 100 cc, the effect is not greatly improved and it is not economical.

  Anion-exchange minerals include, for example, natural layered double hydroxides that have double hydroxide as the main skeleton such as hydrotalcite, manaceite, pyroaulite, sjoglenite, patina, synthetic hydrotalcite and hydrotalcite-like Materials, clay minerals such as allophane, imogolite, kaolin and the like. Examples of the anion exchange resin include weakly basic anion exchange resins and strong basic anion exchange resins. Among these, the hydrotalcite used in this embodiment is preferable. An anion exchange mineral and an anion exchange resin can be used in combination of two or more. The anion exchange capacity of the anion exchange mineral and the anion exchange resin is set to 5 to 500 meq / 100 cc, preferably 20 to 500 meq / 100 cc, and more preferably 30 to 500 meq / 100 cc. When the anion exchange capacity is less than 5 meq / 100 cc, nutrients cannot be taken in sufficiently, and the taken-up nutrients may be washed away early due to irrigation or the like. On the other hand, even if the fertilizer is excessively increased so that the anion exchange capacity exceeds 500 meq / 100 cc, the effect is not greatly improved and it is not economical.

<Filler granulation method>
When the filler 1 is an inorganic natural mineral such as zeolite 1a or hydrotalcite 1b shown in the present embodiment, a binder is used to collect a plurality of fillers 1 to form a granular material (artificial soil particle 10). Can be granulated. Formation of artificial soil particles 10 using a binder is performed by adding a binder or a solvent to the filler 1 and mixing the mixture, introducing the mixture into a granulator, rolling granulation, fluidized bed granulation, stirring granulation, compression granulation. It can be performed by a known granulation method such as granulation, extrusion granulation, crushing granulation, melt granulation, spray granulation or the like. The obtained granulated body is dried and classified as needed, and the artificial soil particle 10 is completed. In addition, a binder is added to the filler 1 and, if necessary, a solvent or the like is added and kneaded, and the resulting dried and block-shaped material is appropriately pulverized by pulverizing means such as a mortar and pestle, a hammer mill, a roll crusher or the like. It is also possible to obtain a granular material. This granular material can be used as the artificial soil particle 10 as it is, but it is preferable to adjust to a desired particle size by sieving.

  As the binder, either an organic binder or an inorganic binder can be used. Organic binders include, for example, synthetic resin binders such as polyolefin binders, polyvinyl alcohol binders, polyurethane binders, polyvinyl acetate binders, polysaccharides such as starch, carrageenan, xanthan gum, gellan gum, alginic acid, and animal properties such as glue. Examples include natural product-based binders such as proteins. Examples of the inorganic binder include silicate binders such as water glass, phosphate binders such as aluminum phosphate, borate binders such as aluminum borate, and hydraulic binders such as cement. An organic binder and an inorganic binder can be used in combination of two or more.

  When the filler 1 is an organic porous material, the artificial soil particles 10 may be formed by the same method as the above-described filler granulation method using a binder, but the filler 1 constitutes the filler 1. It is also possible to form the artificial soil particles 10 by heating to a temperature equal to or higher than the melting point of the organic porous material (polymer material or the like) to be fused and granulating the surfaces of the plurality of fillers 1 by heat fusion. is there. In this case, a granular material in which a plurality of fillers 1 are assembled can be obtained without using a binder. As such an organic porous material, for example, an organic polymer foam obtained by foaming an organic polymer material such as polyethylene, polypropylene, polyurethane, polyvinyl alcohol, and cellulose, and the powder of the organic polymer material is heated and melted. An organic polymer porous body having an open cell structure is exemplified.

  In forming the artificial soil particles 10, a gelation reaction of a polymer gelling agent can be used. Examples of the gelation reaction of the polymer gelling agent include a gelation reaction of alginate, propylene glycol alginate, gellan gum, glucomannan, pectin, or carboxymethylcellulose (CMC) and a polyvalent metal ion, carrageenan, agar, Examples thereof include a gelation reaction by a double helix structuring reaction of polysaccharides such as xanthan gum, locust bean gum, and tara gum. Among these, the gelation reaction between an alginate and a polyvalent metal ion will be described. Sodium alginate, which is one of alginates, is a neutral salt in which the carboxyl group of alginic acid is bonded to Na ions. Alginic acid is insoluble in water, but sodium alginate is water soluble. When an aqueous sodium alginate solution is added to an aqueous solution of polyvalent metal ions (for example, Ca ions), ionic crosslinking occurs between the molecules of sodium alginate and gelation occurs. In the case of this embodiment, the gelation reaction can be performed by the following steps. First, an alginate aqueous solution is prepared by dissolving alginate in water, filler 1 is added to the alginate aqueous solution, and this is sufficiently stirred to form a mixed solution in which filler 1 is dispersed in the alginate aqueous solution. . Next, the mixed solution is dropped into the polyvalent metal ion aqueous solution, and the alginate contained in the mixed solution is gelled in a granular form. Thereafter, the gelled particles are collected, washed with water, and sufficiently dried. Thereby, the artificial soil particle 10 as the granular material which the filler 1 disperse | distributed in the alginic acid gel formed from an alginate and a polyvalent metal ion is obtained.

  Examples of alginates that can be used in the gelation reaction include sodium alginate, potassium alginate, and ammonium alginate. These alginate can be used in combination of two or more. The concentration of the alginate aqueous solution is 0.1 to 5% by weight, preferably 0.2 to 5% by weight, and more preferably 0.2 to 3% by weight. When the concentration of the alginate aqueous solution is less than 0.1% by weight, the gelation reaction hardly occurs. When the concentration exceeds 5% by weight, the viscosity of the alginate aqueous solution becomes too large. In addition, it is difficult to drop the mixed solution into the aqueous solution of the polyvalent metal ion.

  The polyvalent metal ion aqueous solution to which the alginate aqueous solution is dropped may be a divalent or higher metal ion aqueous solution that reacts with the alginate and causes gelation. Examples of such polyvalent metal ion aqueous solutions include aqueous chloride solutions of polyvalent metals such as calcium chloride, barium chloride, strontium chloride, nickel chloride, aluminum chloride, iron chloride, cobalt chloride, calcium nitrate, barium nitrate, aluminum nitrate. Nitrate aqueous solutions of polyvalent metals such as iron nitrate, copper nitrate and cobalt nitrate, lactate aqueous solutions of polyvalent metals such as calcium lactate, barium lactate, aluminum lactate and zinc lactate, aluminum sulfate, zinc sulfate, cobalt sulfate etc. An aqueous solution of a valent metal sulfate is mentioned. These polyvalent metal ion aqueous solutions can be used in combination of two or more. The concentration of the polyvalent metal ion aqueous solution is 1 to 20% by weight, preferably 2 to 15% by weight, and more preferably 3 to 10% by weight. When the concentration of the polyvalent metal ion aqueous solution is less than 1% by weight, the gelation reaction hardly occurs. When the concentration exceeds 20% by weight, it takes time to dissolve the metal salt and excessive materials are used. Not economical.

<Porous structure of artificial soil particles>
The granular material obtained by each method illustrated above constitutes the artificial soil particle 10 of the present invention in which a plurality of fillers 1 having pores 2 in the order of sub-nm to sub-μm are assembled. The particle size of the artificial soil particles 10 (average value of the size z of the artificial soil particles 10 shown in FIG. 1) is 0.2 to 10 mm, preferably 0.5 to 5 mm, more preferably 1 to 5 mm. is there. Adjustment of the particle size of the artificial soil particle 10 can be performed by classification with a sieve, for example. A communication hole 3 is formed between the plurality of fillers 1 constituting the artificial soil particle 10. When the particle diameter of the artificial soil particles 10 is less than 0.2 mm, the gap between the artificial soil particles 10 is reduced and the drainage performance is lowered, so that the plant to be cultivated may hardly absorb oxygen from the roots. On the other hand, if the particle size of the artificial soil particles 10 exceeds 10 mm, the gap between the artificial soil particles 10 becomes large and the drainage property becomes excessive, so that it becomes difficult for the plant to absorb moisture, or the artificial soil particles 10 There is a risk that the plant will fall on its side. The size of the communication hole 3 (the average value of the distance y between adjacent fillers 1 shown in FIG. 1) can vary depending on the type, composition, and granulation conditions of the filler 1 and the binder. Become. For example, the size of the communication hole 3 can be set to about 0.1 to 500 μm, but the filler 1 is the zeolite 1a shown in FIG. 1 (a) or the hydrotalcite 1b shown in FIG. 2 (b). When the polymer gelling agent is used, the size of the communication hole 3 is 0.1 to 20 μm. The size of the communication hole 3 is measured by an optimal method using a gas adsorption method, a mercury intrusion method, a small-angle X-ray scattering method, an image processing method, or a combination of these methods depending on the state of the measurement object can do. The particle diameter of the artificial soil particle 10 can be measured using, for example, optical microscope observation and an image processing method. In the present embodiment, the size of the communication hole 3 and the particle size of the artificial soil particle 10 were measured by the following measurement method. First, the artificial soil particles to be measured are observed together with a scale with a microscope, and the microscope image is acquired using image processing software (two-dimensional image analysis processing software “WinROOF”, manufactured by Mitani Corporation). 100 artificial soil particles are selected from the image and the outline of the communication hole or artificial soil particle is traced. The diameter of the equivalent circle is calculated from the circumference of the traced figure. The average of the diameters (100) of the equivalent circles obtained from the respective communicating holes or artificial soil particles is defined as the average size (unit: pixel). Then, the average size is compared with the scale in the microscopic image, converted into a unit length (μm order to mm order), and the size of the communication hole or the particle size of the artificial soil particles is calculated.

  The artificial soil particle 10 of the present invention is unique in that a specific relationship is provided between the pore 2 of the filler 1 and the communication hole 3 formed between the filler 1 in one particle. Have That is, the pores 2 and the communication holes 3 existing in the artificial soil particle 10 are arranged so that the communication holes 3 take in moisture and nutrients from the outside, and the pores 2 can receive nutrients from the communication holes 3. Are distributed around the communication hole 3.

  FIG. 2 is a model diagram conceptually showing the positional relationship between the pores 2 and the communication holes 3 of the artificial soil particle 10 of the present invention. FIG. 2 models the internal structure of the artificial soil particle 10 shown in FIG. 1, but does not reflect the actual internal structure of the artificial soil particle 10 as it is. In the artificial soil particle 10 of the present invention, the pores 2 are dispersedly arranged around the communication holes 3. The pores 2 are connected to the communication holes 3 and the pores 2 connected to the communication holes 3. Is present substantially throughout the periphery of the communication hole 3. For example, referring to FIG. 2A, a large number of pores 2 of size x are connected to a communication hole 3 of size y, and a large number of pores 2 extend along the entire length of the communication hole 3. The existing state is shown. Such a specific positional relationship between the pore 2 and the communication hole 3 is a great feature of the present invention. This specific positional relationship may be approximately half or more of the pores 2 and the communication holes 3. In FIG. 2A, for the sake of space, a specific positional relationship between the pore 2 and the communication hole 3 is shown two-dimensionally, but the actual artificial soil particle 10 has a three-dimensional spread. Thus, the above-described specific positional relationship is formed. The conditions for causing the specific positional relationship between the pores 2 and the communication holes 3 to appear have not yet been clarified yet. For example, a material having high crystallinity can be selected as the filler 1, A material having a unique crystal structure is selected as the filler 1, a plurality of types are used as the filler 1 in a specific combination, the crystal structure or layer structure of the filler 1 is controlled, or the filler 1 is oriented. Possibility to make it appear stronger by processing, adding a specific additive when granulating the filler 1 or optimizing the granulation method (granulation conditions) of the filler 1 It is thought that there is.

<Mechanism of water retention and fertilization of artificial soil particles>
Since the artificial soil particles 10 of the present invention have a specific positional relationship between the pores 2 and the communication holes 3, the high-quality and functional excellent balance of basic performance (water retention and fertilizer retention) as soil. It can be artificial soil. Here, the water retention and fertilizer retention mechanisms of the artificial soil particles 10 will be described in detail with reference to FIGS. 2A to 2C show the state in which moisture W and nutrients K, N, and P are taken into the artificial soil particle 10 from outside. Here, nutrient K represents potassium, nutrient N represents nitrogen, and nutrient P represents phosphorus.

  In a state where moisture N and nutrients K, N, and P have not yet been taken into the artificial soil particles 10 from the outside, as shown in FIG. 2A, the artificial soil particles 10 are connected to the communication holes 3 and the communication holes 3. The connecting pores 2 are voids. When the artificial soil particles 10 come into contact with the moisture W containing the nutrients K, N, and P, the moisture W and the nutrients K, N, and P are first taken into the communication holes 3 as shown in FIG. When the communication hole 3 is sufficiently wet, as shown in FIG. 2 (c), among the water W and the nutrients K, N, and P taken into the communication hole 3, the nutrients K, N, and P are the communication holes. 3 to the pore 2. In the artificial soil particle 10 of the present invention, nutrients K, N, and P are mainly taken into the pores 2 and moisture W is held in the communication holes 3 so that the pores 2 are mainly responsible for fertilization. In addition, the communication hole 3 is responsible for water retention. Thus, by assigning different functions between the pores 2 and the communication holes 3, it is possible to obtain functional artificial soil particles 10 having an excellent balance between water retention and fertilizer retention. Moreover, since artificial soil using such artificial soil particles 10 can appropriately supply moisture W and nutrients K, N, and P to the plant to be cultivated, maintenance is not required and handling is easy. It will be a thing.

<Physical properties of artificial soil particles>
The pores 2 and the communication holes 3 of the artificial soil particles 10 are preferably configured so that the total volume of the communication holes 3 is larger than the total volume of the pores 2. This is to ensure sufficient water retention of the communication holes 3 and to smoothly move nutrients from the communication holes 3 to the pores 2. Moreover, since the artificial soil particle 10 will become lightweight if the total volume of the communicating hole 3 becomes larger than the total volume of the pore 2, the bulk density will become small and the handling as artificial soil will also become easy. In order to make the total volume of the communication hole 3 larger than the total volume of the pore 2, the filler 1 is combined in a three-dimensional network. This is because, for example, when the filler 1 is granulated, for example, a porous binder is used, or the filler 1 is dried by a freeze-drying method or the like. This can be done by combining them. In this case, the plurality of fillers 1 are three-dimensionally bonded while forming a large number of voids, and a filler aggregate (artificial soil particle 10) having a three-dimensional network structure is formed. Filler aggregates combined in a three-dimensional network form are suitably used as artificial soil particles 10 that have the strength necessary for cultivation of root vegetables because they are low in bulk density and are light and structurally stable. it can. In addition, because of the large number of voids inside, the basic performance as soil such as water retention, fertilizer retention, drainage, and breathability is good, and artificial soil with high added value can be obtained.

  The strength of the artificial soil particles 10 can be evaluated by a volume change rate by repeatedly applying a compressive load. The artificial soil particle 10 of the present invention is designed such that the volume change rate after repeated application of a compressive load of 25 KPa is 20% or less. A preferable volume change rate is 15% or less. When the volume change rate exceeds 20%, the artificial soil particles 10 are easily pulverized when the planter is filled with artificial soil or seedlings are transplanted, and the structure of the artificial soil particles 10 (the pores 2 of the filler 1). May be dispersed around the communication holes 3 between the plurality of fillers 1, and the filler 1 may be lost in a three-dimensional network structure. As a result, the balance between water retention and fertilizer retention is lost. Further, when the structure of the artificial soil particles 10 is lost, the artificial soil is easily compacted, which may adversely affect the cultivation of root vegetables.

  Although the artificial soil particle 10 of the present invention is suitable for cultivation of root vegetables, since it has excellent water retention as artificial soil, it is used for the cultivation of leafy vegetables that have been mainly hydroponically cultivated so far. It is also possible to apply. Here, the water retention capacity of the artificial soil can be evaluated based on the water retention capacity. The water retention amount is obtained as a water retention amount (%) per 100 mL of artificial soil particles. The artificial soil particle 10 of the present invention has a unique structure in which the pores 2 of the filler 1 are dispersedly arranged around the communication holes 3 between the plurality of fillers 1 and the filler 1 is combined in a three-dimensional network. The water retention amount can be set to 20 to 70%. If the water retention amount is lower than 20%, it will be difficult to retain sufficient water for the plant to grow, and if it exceeds 70%, the air permeability of the artificial soil will deteriorate, which may adversely affect the growth of the plant. There is. The air permeability can be expressed by the gas phase rate of the artificial soil in a dry state. The gas phase rate of the artificial soil using the artificial soil particles 10 of the present invention can be set to be 20 to 80%. A preferable gas phase rate is 30 to 80%, and a more preferable gas phase rate is 30 to 70%. When the gas phase rate is less than 20%, the amount of air supplied to the plant root is insufficient, and when it exceeds 80%, there is a possibility that sufficient water retention cannot be secured.

  In designing the artificial soil particles 10, it is possible to further increase the water retention capacity of the communication holes 3. One method for improving the water retention of the communication hole 3 is to introduce a water retention material into the communication hole 3 of the artificial soil particle 10. The water retention material can be introduced, for example, by filling the entire communication hole 3 with a water retention material or coating the surface of the communication hole 3 with a film of the water retention material. At this time, the water retaining material only needs to be present in at least a part of the communication hole 3. For example, the water-retaining material is introduced by mixing and granulating a water-retaining polymer material, or preparing a polymer solution by dissolving the water-retaining polymer material in a solvent, It is carried out by impregnating the artificial soil particles 10.

  Examples of polymer materials that can be used as water-retaining materials include synthetic polymer water-retaining properties such as polyacrylate polymers, polysulfonate polymers, polyacrylamide polymers, polyvinyl alcohol polymers, and polyalkylene oxide polymers. Examples thereof include natural polymeric water-retaining materials such as materials, polyaspartate-based polymers, polyglutamate-based polymers, polyalginate-based polymers, cellulose-based polymers, and starches. These water retaining materials can be used in combination of two or more.

  The solvent that dissolves the polymer material, which is a water-retaining material, has a high solubility depending on the polymer material used, that is, a combination in which the solubility parameter (SP value) is close between the polymer material and the solvent is appropriate. Selected. For example, a combination in which the difference between the SP value of the polymer material and the SP value of the solvent is 5 or less (eg, a combination of nitrocellulose having an SP value of about 10 and methanol having an SP value of about 14.5) Is selected. Examples of such solvents include methanol, ethanol, isopropanol, butanol, ethyl acetate, acetone, methyl ethyl ketone, methyl isobutyl ketone. These solvents can be used in combination of two or more.

  As another method for improving the water retention of the communication hole 3, in preparing the artificial soil particles 10, it is possible to use a water retention filler for a part or all of the filler 1 as a raw material. In this case, the generated artificial soil particles 10 themselves have water retention properties, so that a special post-treatment for improving the water retention properties is not necessary. Hydrophilic fillers and porous granular materials can be used as water retention fillers, and examples of hydrophilic fillers include zeolite, smectite minerals, mica minerals, talc, silica, and double hydroxides. Examples of the porous particulate material include foamed glass, porous metal, porous ceramic, polymer porous body, and hydrophilic fiber.

<Artificial soil aggregate>
The artificial soil particles 10 of the present invention can be further aggregated and used as artificial soil in the form of artificial soil aggregates. FIG. 3 is a schematic diagram of the artificial soil aggregate 100 of the present invention. Here, the artificial soil aggregate 100 which aggregated the artificial soil particle 10 using the zeolite 1a shown to Fig.1 (a) is illustrated.

  The artificial soil aggregate 100 has a cluster structure in which a plurality of artificial soil particles 10 are connected. The cluster structure is obtained by bonding a plurality of artificial soil particles 10 with a secondary binder. The secondary binder used for the agglomeration can be the same as the binder (primary binder) used in the formation of the artificial soil particles 10, but may be a different type of binder. The size of the artificial soil aggregate 100 (average value of the size w of the artificial soil aggregate 100 shown in FIG. 3) is 0.4 to 20 mm, preferably 0.5 to 18 mm, more preferably 1 ~ 15 mm. When the size of the artificial soil aggregate 100 is less than 0.4 mm, the gap between the artificial soil particles 10 constituting the artificial soil aggregate 100 is reduced and the drainage performance is reduced, so that the plant to be cultivated from the roots. There is a risk that it may be difficult to absorb oxygen. On the other hand, if the size of the artificial soil particle 10 exceeds 20 mm, the drainage property becomes excessive, and the plant may not easily absorb moisture, or the artificial soil aggregate 100 may be sparse and the plant may fall down. There is. The size of the artificial soil aggregate 100 is measured using, for example, an optical microscope observation and an image processing method. In the present embodiment, the size of the artificial soil aggregate 100 is measured by the measurement method using the image processing described above, similarly to the size of the communication hole 3 and the particle size of the artificial soil particle 10.

  The artificial soil aggregate 100 obtained by agglomerating the artificial soil particles 10 of the present invention has an excellent balance between water retention and fertilizer retention, and appropriately supplies moisture and nutrients to the plant to be cultivated. Can be supplied. Therefore, the artificial soil aggregate 100 of the present invention is useful as artificial soil that does not require maintenance and is easy to handle.

  The Example regarding the artificial soil particle | grains of this invention and an artificial soil aggregate is demonstrated. As Examples 1 to 3, artificial soil particles of the present invention were prepared by different granulation methods (granulation method, pulverization method, gelation method). Further, as Example 4, the artificial soil particles of the present invention were aggregated to prepare the artificial soil aggregate of the present invention. About the characteristic of the artificial soil particle and the artificial soil aggregate, it evaluated by the method shown to the following (1)-(6).

(1) Particle size Artificial soil particles or artificial soil aggregates are preliminarily classified to a predetermined particle size by a sieve, and the particle size is measured by the measurement method using the image processing described in the above embodiment for the classified particles. This was used as a sample.

(2) Pore size The pore size of the pores of the filler constituting the artificial soil particles was measured by a gas adsorption method. The pore diameter (pore diameter distribution) of the communication holes formed between the plurality of fillers was measured by a mercury intrusion method. The pore size distribution will be described in detail later in “Pore size distribution of artificial soil particles”.

(3) Cation exchange capacity An extract of artificial soil particles was prepared using a general-purpose extraction / filtration device “CEC-10 Ver. 2” manufactured by Fujihira Kogyo Co., Ltd., and this was used as a sample for measuring the cation exchange capacity. did. And the cation exchange capacity | capacitance (CEC) of the artificial soil particle | grains was measured using the soil and crop body integrated analyzer "SFP-3" by Fujihira industry.

(4) Anion exchange capacity 20 mL of 0.05 M calcium nitrate solution was added to 2 g of the artificial soil particles and stirred for 1 hour. The solution was centrifuged (10,000 rpm) at room temperature for 1 minute, and the supernatant was used as a measurement sample. About the sample for a measurement, the light absorbency of wavelength 410nm was measured using the ultraviolet visible spectrophotometer, and the calcium nitrate density | concentration was calculated | required. From the difference between the obtained calcium nitrate concentration and the blank calcium nitrate concentration, the adsorption amount per weight of nitrate nitrogen was calculated, and this was converted to the specific gravity to obtain the anion exchange capacity (AEC) per volume.

(5) Strength The strength of the artificial soil particles was evaluated based on the volume change rate due to repeated addition of compressive load. The volume change rate was determined by the following method. A sample cylinder (inner diameter: about 5 cm, height: about 5 cm, volume: 100 mL) for soil evaluation is filled with 100 mL of artificial soil as a sample, and a cylindrical weight (weight: 5 kg) slightly smaller in diameter than the sample cylinder Was slowly placed on top of the sample. In that state, it was left for 60 seconds, and the weight was removed. These operations were repeated 10 times (repeated compression load 25 KPa). When the application of the compressive load was completed repeatedly, the sample was left as it was for 60 seconds, the volume V of the sample was measured using a graduated cylinder or the like, and the volume change rate ΔV was obtained from the following formula [1].
ΔV (%) = (100−V) / 100 × 100 (1)

(6) Amount of water retained The released chromatograph tube was filled with 100 mL of artificial soil particles, and the amount of water retained in the artificial soil when 200 mL of water was slowly poured from above was used as the water retention amount.

(7) Vapor rate A sample was prepared by immersing artificial soil composed of artificial soil particles in tap water for 24 hours to obtain a saturated water content, and the sample was allowed to stand for another hour. After flowing down the weight water of the sample, it was collected in a 100 mL sample cylinder while maintaining the shape as much as possible, and set in a digital real volume measuring device “DIK-1150” manufactured by Dairika Kogyo Co., Ltd. Was measured.

[Example 1]: Granulation method Zeolite was used as a filler and polyethylene emulsion was used as a binder. 100 parts by weight of an artificial zeolite “Ryukyu Light 600” manufactured by Ecowell Co., Ltd. and 5 parts by weight of a polyethylene emulsion “Sepoljon (registered trademark) G” manufactured by Sumitomo Seika Co., Ltd. are mixed and granulated with stirring. And then dried at 120 ° C. for 24 hours and classified with a sieve to obtain artificial soil particles with 2 mm over and 4 mm under. The obtained artificial soil particles had a plurality of fillers having pores in the order of sub-nm order to sub-μm order, and communication holes in the order of sub-μm order to sub-mm order were formed between the fillers. . Further, the pores were dispersedly arranged over the entire periphery of the communication hole. The artificial soil particles had a cation exchange capacity of 18 meq / 100 cc. Furthermore, the strength (volume change rate) of the artificial soil using the artificial soil particles was 15%, the water retention amount (water retention amount) was 28%, and the gas phase rate was 35%.

[Example 2]: Grinding method Hydrotalcite was used as a filler and polyethylene emulsion was used as a binder. 100 parts by weight of reagent hydrotalcite manufactured by Wako Pure Chemical Industries, Ltd. and 5 parts by weight of polyethylene emulsion “Sepoljon (registered trademark) G” manufactured by Sumitomo Seika Co., Ltd. are mixed with stirring, and the mixture is used as a dryer. It was introduced and dried at 120 ° C. for 24 hours to obtain a block-like product. This block-like product was pulverized using a mortar and pestle and classified by sieving to obtain artificial soil particles having a 2 mm over and a 4 mm under. The obtained artificial soil particles had a plurality of fillers having pores in the order of sub-nm order to sub-μm order, and communication holes in the order of sub-μm order to sub-mm order were formed between the fillers. . Further, the pores were dispersedly arranged over the entire periphery of the communication hole. The anion exchange capacity of the artificial soil particles was 15 meq / 100 cc. Furthermore, the strength (volume change rate) of the artificial soil using the artificial soil particles was 12%, the water retention amount (water retention amount) was 25%, and the gas phase rate was 37%.

[Example 3]: Gelling method Zeolite and hydrotalcite were used as fillers, sodium alginate was used as an alginate, and a 5% calcium chloride aqueous solution was used as an aqueous polyvalent metal ion solution. A reagent sodium alginate manufactured by Wako Pure Chemical Industries, Ltd. was dissolved in water to prepare an aqueous solution having a concentration of 0.5%, and an artificial zeolite “Ryukyu Light 600 manufactured by Ecowell Co., Ltd. was added to 100 parts by weight of an aqueous 0.5% sodium alginate solution. 10 parts by weight and 10 parts by weight of a reagent hydrotalcite manufactured by Wako Pure Chemical Industries, Ltd. were added and mixed. The mixed solution was dropped into a 5% calcium chloride aqueous solution at a rate of 1 drop / second. After the dropped droplets were gelled, the particulate gel was recovered, washed with water, and dried for 24 hours with a dryer set at 55 ° C. The dried particulate gel was classified by sieving to obtain artificial soil particles of 2 mm over and 4 mm under. The obtained artificial soil particles had a plurality of fillers having pores in the order of sub-nm order to sub-μm order, and communication holes in the order of sub-μm order to sub-mm order were formed between the fillers. . Further, the pores were dispersedly arranged over the entire periphery of the communication hole. The artificial soil particles had a cation exchange capacity of 14 meq / 100 cc and an anion exchange capacity of 15 meq / 100 cc. Furthermore, the strength (volume change rate) of the artificial soil using the artificial soil particles was 13%, the water retention amount (water retention amount) was 26%, and the gas phase rate was 33%.

[Example 4]: Artificial soil aggregate 100 parts by weight of a pulverized product of artificial soil particles obtained in Example 3 and a vinyl acetate resin adhesive “Bond (registered trademark)” manufactured by Konishi Co., Ltd. as a secondary binder. 5 parts by weight for woodworking were mixed, the mixture was introduced into a granulator and agglomerated to obtain an artificial soil aggregate. The obtained artificial soil aggregate had a particle size of 3 to 18 mm and a cluster structure in which a plurality of artificial soil particles were connected.

[Pore size distribution of artificial soil particles]
In order to confirm that the artificial soil particles of the present invention have a porous structure, the pore size distribution was measured by mercury porosimetry. FIG. 4 is a graph showing the measurement results of the pore size distribution of the artificial soil particles or artificial soil aggregates of the present invention by mercury porosimetry. The pore size distribution was measured by (a) lyophilized artificial soil particles (artificial soil particles obtained by changing the drying method to lyophilization method in Example 3), and (b) artificial soil particles (0.1-0. 25 μm single particles) which are hardened with vinyl acetate resin and aggregated to about 3φ (3 mm) (artificial soil aggregate corresponding to Example 4), (c) a cross-linking agent (Nisshinbo Chemical Co., Ltd.) to artificial soil particles Crosslinking agent manufactured by Co., Ltd .: Carbodilite (registered trademark) 0.7%) and further crosslinked (artificial soil particles based on the artificial soil particles of Example 3 and prepared with a higher crosslinking density) Three types of artificial soil particles or artificial soil aggregates were targeted. From FIG. 4, the artificial soil particles of (a) were confirmed to have peaks at two locations around 30 nm and around 2 μm. The peak near about 30 nm is presumed to be a minute gap formed between fillers, and the peak near about 2 μm is presumed to be a communicating hole. About the artificial soil aggregate of (b), the peak was confirmed by three places, about 50 nm vicinity, about 0.65 micrometer vicinity, and about 20 micrometer vicinity. A peak near about 50 nm is presumed to be a minute gap formed between fillers, and a peak near about 0.65 μm is presumed to be a communicating hole. Moreover, it is estimated that the peak of about 20 micrometers is equivalent to the clearance gap between the particles by agglomeration, and this clearance gap can also be considered as a kind of communicating hole. Regarding the artificial soil particles of (c), peaks were confirmed at two locations near about 50 nm and about 0.65 μm. A peak near about 50 nm is presumed to be a minute gap formed between fillers, and a peak near about 0.65 μm is presumed to be a communicating hole. Thus, the artificial soil particle or artificial soil aggregate of the present invention has sub-μm order to sub-mm order communication holes, and is combined with the sub-nm order to sub-μm order pores of the filler. It was confirmed to have a unique porous structure with two types of size distributions.

  The artificial soil particles and artificial soil aggregates of the present invention can be used for artificial soil used in plant factories, etc., but as other uses, facility horticultural soil, greening soil, molded soil, soil improvement It can also be used as an agent and soil for interiors.

DESCRIPTION OF SYMBOLS 1 Filler 2 Pore 3 Communication hole 10 Artificial soil particle 100 Artificial soil aggregate

Claims (6)

Artificial soil particles in which a plurality of fillers having pores on the order of sub-nm to sub-μm are assembled,
A communication hole in the order of sub μm to sub mm is formed between the fillers,
Artificial soil particles in which the pores are dispersed and arranged around the communication holes so that the communication holes take in moisture and nutrients from the outside and the pores can receive the nutrients from the communication holes.   The artificial soil particle according to claim 1, wherein the filler is bound in a three-dimensional network so that the total volume of the communication hole is larger than the total volume of the pore.   The artificial soil particle according to claim 1 or 2, wherein a water-retaining material is introduced into at least a part of the communication hole, and ion exchange ability is imparted to the pore.   The artificial soil particle according to any one of claims 1 to 3, wherein a pore diameter of the pore is 0.2 to 800 nm, and a pore diameter of the communication hole is 0.1 to 500 µm.   The artificial soil particle according to any one of claims 1 to 4, which has a particle size of 0.2 to 10 mm.   The artificial soil aggregate which aggregated the artificial soil particle as described in any one of Claims 1-5.

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