JP2014113086A - Artificial soil particle and artificial soil culture medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an artificial soil particle that can maintain basic performance as soil even when external pressure and the like are received, the artificial soil particle having a good workability as well.SOLUTION: An artificial soil particle 10 is provided, comprising a base part composed of an aggregation of a plurality of fillers 1 having pores 2, at least the inside of the base part being reinforced with reinforcement material 5. The pores 2 have a size of from sub-nm order to sub-μm order, and communication holes 3 having a size of from sub-μm order to sub-mm order are formed among the fillers 1. The communication holes 3 take in water and nutrients from outside, and the pores 2 are dispersively arranged around the communication holes 3 so that the pores 2 can receive the nutrients from the communication holes 3.

Description

  The present invention relates to an artificial soil particle in which a plurality of fillers are aggregated, and an artificial soil medium using the artificial soil particle.

  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 an artificial soil developed so far, there is a porous artificial soil body in which at least one structural component of organic matter, inorganic matter and soil, and solid matter such as gypsum are partially combined with a cured product of water-soluble urethane polymer. (For example, see Patent Document 1). The porous artificial soil body of Patent Document 1 has improved water retention by forming pores capable of holding water in the artificial soil body by partially combining solids.

  Further, there has been aggregated structure zeolite obtained by combining powdery zeolite with a binding material made of a water-soluble polymer to aggregate (for example, see Patent Document 2). The aggregated structure zeolite of Patent Document 2 has improved water retention by forming a aggregated structure of zeolite to form pores capable of retaining water in the aggregated body.

JP-A-5-244820 JP 2000-336356 A

  In the development of artificial soil particles, it is desired to have a high strength and good workability in order to maintain the ability while achieving plant growth ability equivalent to that of natural soil. In this respect, the artificial soil of Patent Document 1 cannot be said to have sufficient strength because the solid form of the solid matter formed by the cured product of the water-soluble urethane polymer is partial. For this reason, the structure of artificial soil particles is destroyed during operations such as planting, and water retention may be reduced. In addition, when the artificial soil particles are destroyed, fine powder that hinders the work is generated, and the cohesive force between the artificial soil particles is weakened, so that workability may be reduced.

  The aggregated structure zeolite of Patent Document 2 is obtained by simply mixing a powdered zeolite and a binder in the presence of water and drying them, so that the bonding force between the zeolite particles may not be sufficient. When an operation such as planting is performed using this aggregate structure zeolite, the aggregate structure is destroyed by an external pressure or the like, so that there is a possibility that the basic performance of the soil is lowered or the workability is lowered.

  The present invention has been made in view of the above problems, and can provide artificial soil particles that can maintain basic performance as soil even when subjected to external pressure or the like and have good workability. With the goal. Another object of the present invention is to provide an artificial soil medium using such artificial soil particles.

The characteristic configuration of the artificial soil particles according to the present invention for solving the above problems is as follows:
A base portion formed by a plurality of fillers having pores is provided, and at least the inside of the base portion is reinforced with a reinforcing material.

  Since the artificial soil particle of this structure comprises a plurality of fillers having pores to form a base, moisture is absorbed between the fillers and nutrients necessary for plants are taken into the filler pores. It becomes possible to have basic performance as soil. In order to maintain the basic performance of the artificial soil particles, it is required to stabilize the structure. However, since the artificial soil particles of this configuration are reinforced with a reinforcing material at least inside the base, The structure is stabilized. For this reason, for example, even when an external pressure is applied at the time of work such as planting, the structure of the artificial soil particles is difficult to be destroyed. Moreover, since the fine powder etc. which originate in destruction of the artificial soil particle do not generate | occur | produce, workability | operativity in planting etc. does not fall.

In the artificial soil particles according to the present invention,
The pores preferably have a size in the order of sub-nm to sub-μm, and communication holes in the order of sub-μm to sub-mm are preferably formed between the fillers.

  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 the artificial soil particles according to the present invention,
It is preferable that 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 the nutrients from the communication holes.

  According to the artificial soil particles of this configuration, with respect to the positional relationship between the pores and the communicating holes, the communicating holes take in moisture and nutrients from the outside, and the pores can receive nutrients from the communicating holes. Since it is dispersedly arranged around the communication holes, the pores can be mainly 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 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 configuration, since the filler is combined 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 can be reduced in weight. .

In the artificial soil particles according to the present invention,
The reinforcing material is preferably at least one substance selected from the group consisting of natural polysaccharides, natural resins, synthetic resins, resin crosslinking agents, inorganic binders, and fibers.

  According to the artificial soil particles of this configuration, at least one substance selected from the group consisting of natural polysaccharides, natural resins, synthetic resins, resin cross-linking agents, inorganic binders, and fibers is used as the reinforcing material. By doing so, sufficient strength can be given to the artificial soil particles.

In the artificial soil particles of this configuration,
It is preferable that ion exchange capacity is imparted to the pores.

  According to the artificial soil particle of this configuration, since the ion exchange ability is imparted to the pores, nutrients contained in moisture taken into the base from the external environment can be adsorbed to the pores. Thereby, the artificial soil particle which improved the fertilizer retention which can endure long-term use is realizable.

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 culture medium according to the present invention for solving the above problems is as follows.
The use of the artificial soil particles according to any one of the above.

  According to the artificial soil culture medium of this configuration, since the artificial soil particles of the present invention are used, an artificial soil culture medium having excellent strength can be realized while maintaining the basic performance as soil. Moreover, since such an artificial soil culture medium can supply a water | moisture content and nutrients appropriately with respect to the plant of cultivation object, it does not take a maintenance effort and becomes what is easy to handle.

FIG. 1 is an explanatory diagram conceptually showing the artificial soil particles and the artificial soil medium of the present invention. FIG. 2 is an explanatory view conceptually showing the pores and communication holes of the artificial soil particles of the present invention.

  Hereinafter, the embodiment regarding the artificial soil particle and artificial soil culture medium which concern on this invention is described based on FIG.1 and FIG.2. However, the present invention is not intended to be limited to the configurations described in the embodiments and drawings described below.

<Artificial soil particles and artificial soil medium>
FIG. 1 is an explanatory view conceptually showing an artificial soil medium 100 using the artificial soil particles 10 of the present invention. A dotted circle shown in FIG. 1 is a partially enlarged view of the artificial soil particle 10 constituting the artificial soil culture medium 100 and represents a cross section of the artificial soil particle 10. The artificial soil culture medium 100 is composed of artificial soil particles 10, and has a certain gap 11 between adjacent artificial soil particles 10. Since this gap 11 allows air and water to pass therethrough, excess water can be discharged while holding water necessary for the plant. When the artificial soil culture medium 100 becomes wet, excess water is discharged from the gap 11, and when the artificial soil culture medium 100 becomes dry, the surrounding water is sucked up by capillary action of the gap 11. be able to. As described above, the artificial soil culture medium 100 realizes excellent air permeability and drainage by the gaps 11 formed between the adjacent artificial soil particles 10. In addition, the gap 11 provides a space for the plant roots to grow, so that the plant roots can be easily stretched, and thus the plant growth can be promoted. As described above, in order to maintain the functions (breathability and drainage) as the artificial soil culture medium 100, it is necessary to stabilize the structure of the artificial soil particles 10 in addition to the basic performance as the soil. Therefore, the artificial soil particles 10 of the present invention are devised for stabilizing the structure. Hereinafter, the artificial soil particles 10 constituting the artificial soil medium 100 will be described in detail.

  The cross-sectional view of the artificial soil particle 10 in FIG. 1 illustrates the cross section of the artificial soil particle 10 formed using the zeolite-like filler 1 which is a porous natural mineral. The base part that forms the main structure of the artificial soil particle 10 is configured such that a plurality of fillers 1 having pores 2 are aggregated to form a granular shape, and communication holes 3 are formed between the plurality of fillers 1. The base of the artificial soil particle 10 will be described in detail later.

  The communication hole 3 formed inside the artificial soil particle 10 is connected to the external environment of the artificial soil particle 10 to ensure water permeability between the inside of the artificial soil particle 10 and the external environment. While taking in the nutrients, the nutrients are transferred from the communication holes 3 to the pores 2 of the filler 1. Here, the “external environment” intends an environment outside the artificial soil particles 10. In the artificial soil culture medium 100 in a state where the plurality of artificial soil particles 10 shown in FIG. 1 are gathered, a gap 11 formed between the plurality of artificial soil particles 10 corresponds to the external environment. The external environment may contain moisture necessary for plant growth.

  It is not essential that the fillers 1 in the artificial soil particles 10 are in contact with each other. For example, relative to each other within a certain range via the network structure 4 by a binder, a gelling agent, or the like in one particle. If such a positional relationship is maintained, it can be considered that a plurality of fillers 1 gather to form the base of the granular artificial soil particles 10. As shown in FIG. 1, the base portion of the artificial soil particle 10 has a porous structure in which communication holes 3 are formed between the fillers 1 by combining a plurality of fillers 1 having pores 2 with a network structure 4. ing. In FIG. 1, the positional relationship between the pore 2 and the communication hole 3 is shown two-dimensionally for the sake of space, but the actual artificial soil particle 10 has a structure in which the filler 1 is combined three-dimensionally. It has become.

  The communication hole 3 is configured so as to be surrounded by a plurality of fillers 1, and the fillers 1 are connected by a network structure 4 so that the structure of the communication holes 3 is maintained. The communication hole 3 has an ability to retain water given from the external environment, and the water retention of the artificial soil particles 10 can be adjusted by changing the size of the communication hole 3. The size of the communication hole 3 can be adjusted by changing the size of the network structure 4. However, when the size of the network structure 4 is increased, between the adjacent fillers 1 and between the network structure 4 and the filler 1. A gap or the like may occur, and the strength of the artificial soil particle 10 as a whole may be weakened. In this case, if an external force is applied to the artificial soil culture medium 100 at the time of planting or the like, the base structure of the artificial soil particles 10 may be destroyed, and the basic performance as soil may not be maintained. Moreover, when using the artificial soil culture medium 100 over a long period of time, the binder or gelling agent deteriorates due to root acid (citric acid or the like) produced by plants, phosphoric acid added as a nutrient, resident microorganisms, ultraviolet rays, etc. The strength of the artificial soil particles as a whole may decrease, and the basic performance as soil may not be maintained. Furthermore, when carrying nutrients such as potassium, phosphoric acid, nitrogen, etc. inside the artificial soil particles 10, when using a binder or gelling agent that easily causes a chemical reaction with these components or is easily combined In addition, since the binder and the gelling agent are easily decomposed, the strength of the artificial soil particles as a whole is lowered, and the basic performance as soil may not be maintained. Due to the destruction or deterioration of the structure of the base of these artificial soil particles 10, fine powder which hinders work is generated, and the cohesive force between the artificial soil particles 10 is weakened, so that workability may be reduced. Therefore, in the artificial soil particle 10 of the present invention, the reinforcing material 5 is introduced into the base, and the structure of the base is reinforced at least from the inside. This reinforcement of the structure of the base may target all artificial soil particles 10, but may also target only a specific type of artificial soil particles. As shown in FIG. 1, the reinforcing material 5 is formed by bonding adjacent fillers 1, mesh structures 4, mesh structures 4 and fillers 1 adjacent to each other, covering the mesh structures 4, and mesh structures 4. The cross-linked portion is reinforced by, for example, further cross-linking. Thereby, the structure of the base of the artificial soil particle 10 is reinforced, and the strength of the artificial soil particle 10 is improved. Although not shown in FIG. 1, the network structure 4 not only partially connects the fillers 1 but also spreads so as to cover a plurality of fillers 1 to connect the fillers 1 to each other. The reinforcing material 5 joins the network structures 4 spread between the plurality of fillers 1 and covers the surface of the network structure 4 (including the outer surface portion of the base) over a wide range. Since the network structure 4 of the artificial soil particles 10 is reinforced by these structures, for example, even if there is a phosphoric acid added as a nutrient to the external environment of the artificial soil particles 10 or a root acid secreted by the plant, Since the reinforcing material 5 protects the mesh structure 4, the deterioration of the mesh structure 4 can be prevented, and the durability is improved.

  In the artificial soil particles 10, the pores 2 are dispersed around the communication holes 3 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. It is preferable. In this case, it is necessary to stabilize the positional relationship between the pores 2 and the communication holes 3 of the filler 1. In order to maintain the positional relationship between the pores 2 and the communication holes 3, the reinforcing material 5 is attached to the surface of the filler 1 that forms the periphery of the communication holes 3 for reinforcement. Thereby, the positional relationship between the pore 2 and the communication hole 3 is maintained, and the base structure of the artificial soil particle 10 becomes stable.

  In the artificial soil particles 10, the filler 1 is preferably combined in a three-dimensional network 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 having fertilizer retention. 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, a bulk density will become small and the handling as the artificial soil culture medium 100 will also become easy. However, when the artificial soil particle 10 has the above-described structure, the filler 1 and the network structure 4 included in the base portion of the artificial soil particle 10 are in a sparse state, and the strength of the base portion is likely to decrease. Therefore, in order to prevent such strength reduction, the reinforcing member 5 is attached to the surfaces of the filler 1 and the network structure 4 to reinforce the structure of the base. As a result, the structure in which the filler 1 is combined in a three-dimensional network is stabilized, and a state in which water retention by the communication holes 3 and fertilization by the pores 2 are compatible can be maintained.

<Granulation method of artificial soil particles>
In the case where the filler 1 is an inorganic natural mineral such as zeolite or hydrotalcite, for example, a gelling agent is used to collect a plurality of fillers 1 to form the base (granular material) of the artificial soil particles 10. A plurality of fillers 1 are granulated. In this case, the artificial soil particles 10 are formed by the fillers 1 being combined in a three-dimensional network to form the communication holes 3, and further, by the network structure 4 formed by gelation of the gelling agent and the reinforcing material 5, The base structure of the artificial soil particle 10 is maintained. As a method for granulating the artificial soil particles 10, first, a mixed solution in which the filler 1, the gelling agent, and the reinforcing material 5 are mixed is prepared, and this mixed solution is used as a crosslinking agent or an initiator for causing gelation. A gelled product is formed by dropping into the solution. The produced gelled product is recovered from the solution, washed, and then sufficiently dried to produce a granular material. At this time, the water contained between the fillers 1 evaporates, and a porous structure is formed in the granular material. The reinforcing material 5 is uniformly dispersed in the gelled material, but when the gelled material is dried, the adjacent fillers 1 in the porous structure, the network structure 4 and the network structure 4 are adjacent to each other as the water evaporates. The filler 1 is reinforced by bonding or covering the filler 1 or by further cross-linking the cross-linked portions of the network structure 4 or the network structure 4. In this state, by appropriately heating / cooling the granular material or dehydrating / desolvating, the reinforcing material 5 comes into close contact with the fragile portion generated in the granular material and solidifies. Thereby, the base is reinforced from the inside (inside), and the artificial soil particle 10 having a stable structure is formed.

  In the granulation method using the above-mentioned gelling agent, the following procedure is performed in order to further increase the total volume of the communication holes 3 of the artificial soil particles 10. First, the filler 1, the gelling agent, and the reinforcing material 5 are mixed to prepare a mixed solution. After the air is included in this mixed solution, the solution is dropped into a solution containing a crosslinking agent or an initiator for causing gelation. Thus, a gelled product containing air is produced. The produced gelled product is recovered from the solution, washed, and then sufficiently dried to produce a granular material. At this time, the water contained in the gelled product evaporates, and voids (communication holes 3) are formed in the portion of the gelled product that contained air and in the portion of the gelled product where the water content has evaporated. A granular material having a larger diameter is formed. The total volume of the communication hole 3 can be adjusted by changing the amount of air contained in the gelled product.

  The reinforcing material 5 may be any material that can reinforce the structure of the artificial soil particle 10 at least from the inside (inside), but is preferably water-soluble or water-dispersible. For example, natural polysaccharides, natural resins, Synthetic resins, resin cross-linking agents, inorganic binders and the like can be mentioned. These substances can be used in combination of two or more.

  Examples of substances that can be used for the reinforcing material 5 include the following. Examples of natural polysaccharides include cellulose, starch, carrageenan, agar, alginate, gum arabic, pectin, locust bean gum, xanthan gum, tara gum, guar gum, tamarind seed gum, psyllium seed gum, hyaluronic acid, chitin, chitosan, glue Etc. Examples of natural resins include rosin, lacquer, gypsum, natural rubber, casein, shellac and the like. Synthetic resins include, for example, olefin resin, acrylic resin, urethane resin, epoxy resin, vinyl acetate resin, ethylene vinyl acetate resin, vinyl chloride resin, vinylidene chloride resin, methyl cellulose resin, carboxymethyl cellulose resin, silicone resin, fluorine resin, Examples thereof include phenol resin, ethylene resin, propylene resin, styrene resin, amide resin, imide resin, melamine resin, and urea resin. Examples of the resin crosslinking agent include isocyanate, vinyl sulfone compound, aziridine, dihydrazide, methylated amine, diglycidyl ether, carbodiimide, formaldehyde, titanium coupling agent, and silane coupling agent. Examples of inorganic binders include water glass, phosphate, borate, cement, and the like.

  Gelling agents and binders used to form network structure 4 include cellulose, starch, carrageenan, agar, alginate, gum arabic, pectin, locust bean gum, xanthan gum, tara gum, guar gum, tamarind seed gum, psyllium seed Natural polymers such as gum, chitin, chitosan, glue, olefin resin, acrylic resin, urethane resin, epoxy resin, vinyl acetate resin, ethylene vinyl acetate resin, vinyl chloride resin, vinylidene chloride resin, methyl cellulose resin, carboxy Synthetic polymer systems such as methylcellulose resin, silicone resin, fluororesin, ethylene resin, propylene resin, styrene resin, amide resin, imide resin, melamine resin, urea resin, polyethylene glycol, polypropylene glycol It can be listed, but are preferably alginate. By forming a granulated product of the filler 1 using an alginate, a crosslinking agent, or the like and then drying it, the artificial soil particles 10 having a porous structure in which the filler 1 is bonded in a three-dimensional network can be formed.

  Here, the gelation reaction between alginate, which is a natural polymer gelling agent, and a polyvalent metal ion (crosslinking agent) 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. Manufacture of the artificial soil particle 10 by the gelatinization reaction of alginic acid can be performed by the following processes. First, alginate is dissolved in water to prepare an alginate aqueous solution, filler 1 and reinforcing material 5 are added to the alginate aqueous solution, this is sufficiently stirred, and filler 1 and reinforcing material are added to the alginate aqueous solution. 5 and a uniformly dispersed liquid mixture is formed. Next, the mixed solution is dropped into the polyvalent metal ion aqueous solution to produce an alginate gelled product in which the alginate contained in the mixed solution is gelled in a granular form. Thereafter, the alginate gelled product is recovered, washed with water, and sufficiently dried to form a granular material. In this state, the granular material is heated / cooled at an appropriate temperature, or dehydrated / desolventized so that the reinforcing material 5 in the granular material adheres to the filler 1 and the network structure 4 and is solidified. Thereby, the artificial soil particle 10 in which the filler 1 is dispersed in the network structure 4 of the alginic acid gel formed from the alginate and the polyvalent metal ions and the inside of the base is reinforced by the reinforcing material 5 is obtained.

  Examples of alginates that can be used in the gelation reaction include potassium alginate and ammonium alginate in addition to the above-mentioned sodium 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.

<Strength of artificial soil particles>
The strength of the artificial soil particles 10 reinforced by the reinforcing material 5 can be evaluated by a volume change rate by repeatedly applying a compressive load. The volume change rate can be obtained 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 Gently rest on the sample. Leave in that state for 60 seconds to remove the weight. These operations are repeated 10 times (repeated compression load 25 KPa). When the application of the compressive load is completed repeatedly, the sample is left as it is for 60 seconds, the volume V of the sample is measured using a graduated cylinder or the like, and the volume change rate ΔV is obtained from the following equation [1].
ΔV (%) = (100−V) / 100 × 100 (1)

  The artificial soil particle 10 of the present invention is designed so that the volume change rate after the repeated compression load of 25 KPa is 20% or less, and the preferred 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). Are distributed around the communication holes 3 between the plurality of fillers 1, and the filler 1 is connected to form a three-dimensional network. As a result, the basic performance as soil cannot be maintained, and workability also decreases. 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. The artificial soil particle 10 of the present invention can be easily adjusted to the volume change rate range using the above-mentioned method for granulating artificial soil particles.

<Structure of artificial soil particles>
The artificial soil particles 10 of the present invention are arranged in such a manner that the pores 2 are dispersed around the communication holes 3 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. It has a unique structure. The unique structure of the artificial soil particle 10 will be described. FIG. 2 is an explanatory diagram conceptually showing the pores 2 and the communication holes 3 of the artificial soil particle 10 of the present invention. FIG. 2A illustrates the base portion of the artificial soil particle 10 using the zeolite 1 a which is a porous natural mineral as the filler 1. FIG. 2B illustrates the base portion of the artificial soil particle 10 using the hydrotalcite 1 b which is a layered natural mineral as the filler 1. In FIG. 2, the network structure 4 and the reinforcing material 5 are omitted for easy understanding of the relationship between the pores 2 and the communication holes 3 of the artificial soil particles 10. In addition, the symbols x, y, and z shown in FIG. 2 represent the sizes of the pores 2, the communication holes 3, and the artificial soil particles 10, respectively, but the sizes of x, y, and z on the drawing are actual. It does not reflect the size relationship.

  The filler 1 constituting the base of 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. 2 (a), the voids 2a present in the crystal structure of the zeolite 1a are the pores 2, and the hydrotalcite 1b shown in FIG. 2 (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. 2) is on the order of sub-nm to sub-μm. For example, when the filler 1 is the zeolite 1a shown in FIG. 2A, the size (diameter) of the void 2a existing in the crystal structure of the zeolite 1a is about 0.3 to 1.3 nm. When the filler 1 is the hydrotalcite 1b shown in FIG. 2B, the size (distance) of the interlayer 2b existing in the layer structure of the hydrotalcite 1b is about 0.3 to 3.0 nm. In addition, an organic porous material can also be used as the filler 1, and the diameter x of the pores 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.

  The size of the communication hole 3 (the average value of the distance y between adjacent fillers 1 shown in FIG. 2) can vary depending on the type, composition, and granulation conditions of the filler 1, the gelling agent, and the reinforcing material 5, but is sub-μm. Order or sub-mm order. For example, the filler 1 is the zeolite 1a shown in FIG. 2 (a) or the hydrotalcite 1b shown in FIG. 2 (b), the polymer gelling agent is used as the gelling agent, and the reinforcing material 5 is used. When a polyolefin resin 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. Is done. For example, the size of the communication hole 3 can be measured by the following measurement method. First, the artificial soil particles 10 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 10 are selected from the image, and the outline of the communication hole 3 is traced. The diameter of the equivalent circle is calculated from the circumference of the traced figure. An average of the diameters (100 pieces) of the equivalent circles obtained from the respective communication holes 3 is defined as an average size (unit: pixel). Then, the average size is compared with the scale in the microscope image, converted into a unit length (μm order to mm order), and the size of the communication hole 3 is calculated.

  The particle size of the artificial soil particles 10 (average value of the size z of the artificial soil particles 10 shown in FIG. 2) 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. 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 particle diameter of the artificial soil particles 10 is measured using, for example, an optical microscope observation and an image processing method which are the same methods as those of the communication holes 3. For example, the artificial soil particles 10 may be measured by using the above-described image processing. The particle size can be measured.

  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. The introduction of the water retention material is performed, for example, by dissolving a polymer material having water retention in a solvent to prepare a polymer solution, and impregnating the artificial soil particles 10 with the polymer solution. Alternatively, when the artificial soil particles 10 are granulated, fibers having water retention properties may be mixed in the raw material. In this case, the fiber which is a water retention material can be introduced not only into the communication hole 3 of the artificial soil particle 10 but also to the entire artificial soil particle 10. And as for the artificial soil particle 10 in which the fiber was introduced, the water retention is naturally improved, but the strength and durability of the artificial soil particle 10 are also improved. Therefore, the fiber introduced as the water retention material also functions as a reinforcing material. Examples of fibers that can be introduced into the artificial soil particles 10 include synthetic fibers such as vinylon, urethane, nylon, and acetate, and natural fibers such as cotton, wool, and rayon. Of these fibers, vinylon and cotton are preferred. Furthermore, it is preferable that it is a short fiber as a form of a fiber. The artificial soil particles 10 introduced with the water-retaining material greatly improve the water-retaining ability, so that, for example, even when used in a dry external environment, it is possible to prevent plant dying and poor growth without providing water for a long time. it can. Furthermore, since the strength and durability of the artificial soil particles 10 are improved by introducing the water retention material, a synergistic effect of maintaining the water retention over a long period can be expected.

  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. In addition, a porous material having no ion exchange ability (for example, a polymer foam, a glass foam, etc.) is prepared separately, and a material in which the ion exchange ability is imparted to the pores 2 of the porous material is prepared. It is possible to use the filler 1 by introducing it by press-fitting or impregnation. 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 the cation exchange mineral include zeolite, montmorillonite, bentonite, beidellite, hectorite, saponite, stevensite, and other smectite minerals, mica minerals, and vermiculite. Examples of the cation exchange resin include a weak acid cation exchange resin and a strong acid cation exchange resin. Of these, zeolite or bentonite is preferable. The cation exchange mineral and the cation exchange resin can be used in combination of two or more. The cation exchange capacity in the cation exchange mineral and the cation exchange resin is set to 10 to 700 meq / 100 g, preferably 20 to 700 meq / 100 g, and more preferably 30 to 700 meq / 100 g. When the cation exchange capacity is less than 10 meq / 100 g, the 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 excessive so that the cation exchange capacity exceeds 700 meq / 100 g, 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. Of these, hydrotalcite is preferred. 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 g, preferably 20 to 500 meq / 100 g, and more preferably 30 to 500 meq / 100 g. When the anion exchange capacity is less than 5 meq / 100 g, the 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 fertilizing power is excessive so that the anion exchange capacity exceeds 500 meq / 100 g, the effect is not greatly improved and it is not economical.

  The artificial soil particles reinforced with the reinforcing material of the present invention were subjected to a test for evaluating the strength after reinforcement. The test results will be described below as examples.

<Production of artificial soil particles>
(1) Preparation of granular material According to the composition (% by weight) described in Table 1 below, zeolite as a cation exchange mineral as a filler, hydrotalcite as an anion exchange mineral, reinforcing material (binder, Resin cross-linking agent, etc.) and water retention material (vinylon short fiber, etc.) are added to 0.5% sodium alginate aqueous solution and stirred for 3 minutes using a mixer (SM-L57: manufactured by Sanyo Electric Co., Ltd.). Was made. The obtained mixed solution was dropped into a 5% calcium chloride aqueous solution which is a polyvalent metal ion aqueous solution to produce a gelled product. The produced gelled product was recovered from the solution, washed, and then dried in a dryer at 55 ° C. for 24 hours to produce a granular material. In addition, the artificial soil particles of Examples 15 and 16 were prepared by immersing the above granular material in a resin crosslinking agent shown in Table 1 at 80 ° C. for 3 hours. In the comparative example 1, the said granular material which does not mix a reinforcing material was used as artificial soil particle as it is.
(2) Reinforcement of granular materials (Examples 1 to 16)
Reinforcing materials were introduced into the granules according to the formulation (% by weight) described in Table 1.
Example 1: Artificial soil particles were prepared using a 50% polyolefin emulsion (Sepoljon (registered trademark) G manufactured by Sumitomo Seika Co., Ltd.) as a reinforcing material (binder, the same applies hereinafter).
Example 2: Artificial soil particles were prepared using 50% polyolefin emulsion as a reinforcing material and vinylon short fibers as a water retention material.
Example 3: Artificial soil particles were prepared using 20% vinyl acetate emulsion (CH18 manufactured by Konishi Co., Ltd.) as a reinforcing material.
Example 4: Artificial soil particles were prepared using 20% vinyl acetate emulsion as a reinforcing material and vinylon short fibers as a water retention material.
Example 5: Artificial soil particles were prepared using a 10% ethylene vinyl acetate emulsion (a handicraft bond for cloth manufactured by Kawaguchi Co., Ltd.) as a reinforcing material.
Example 6: Artificial soil particles were prepared using 10% ethylene vinyl acetate emulsion as a reinforcing material and vinylon short fibers as a water retention material.
Example 7: Artificial soil particles were produced using a 10% urethane resin emulsion (cloth / felt craft bond, manufactured by Hamanaka Co., Ltd.) as a reinforcing material.
Example 8: Artificial soil particles were prepared using a 10% urethane resin emulsion as a reinforcing material and vinylon short fibers as a water retention material.
Example 9: An artificial soil particle was prepared using an 80 ° C. solution of 1% agar (manufactured by Wako Pure Chemical Industries, Ltd.) as a reinforcing material.
Example 10: An artificial soil particle was prepared using a 1% agar 80 ° C. solution as a reinforcing material and vinylon short fibers as a water retention material.
Example 11: 0.5% locust bean gum (Soar Locust (registered trademark) A120 manufactured by MRC Polysaccharide Co., Ltd.) and 0.5% xanthan gum (Soxane (registered trademark) XG550 manufactured by MRC Polysaccharide Co., Ltd.) as reinforcing materials Artificial soil particles were prepared using an 80 ° C. solution.
Example 12: An artificial soil particle was prepared by using an 80 ° C. solution of 0.5% locust bean gum and 0.5% xanthan gum as a reinforcing material and vinylon short fibers as a water retention material.
Example 13: Artificial soil particles were prepared using a 1% carbodiimide (Carbodilite (registered trademark)) manufactured by Nisshinbo Chemical Co., Ltd. as a reinforcing material.
Example 14: Artificial soil particles were prepared using a 1% carbodiimide solution as a reinforcing material and vinylon short fibers as a water retention material.
Example 15: A stock solution of ethylene glycol diglycidyl ether (manufactured by Wako Pure Chemical Industries, Ltd.) was used as a reinforcing material, and impregnated and crosslinked with ethylene glycol diglycidyl ether to produce artificial soil particles.
Example 16: A stock solution of ethylene glycol diglycidyl ether was used as a reinforcing material, vinylon short fibers were used as a water retention material, and impregnation and crosslinking with ethylene glycol diglycidyl ether was performed to produce artificial soil particles.

<Test content>
Each of the artificial soil particles produced above (Examples 1 to 16, Comparative Example 1) was impregnated in a 10% citric acid solution and a 5% phosphoric acid solution, respectively. The presence or absence of decay of each artificial soil particle was visually observed, and the resistance of each artificial soil particle to citric acid and phosphoric acid was evaluated. The artificial soil particles that did not disintegrate after 12 hours were evaluated as “◯”, the artificial soil particles that were disintegrated within 1 to 12 hours were Δ, and the artificial soil particles that were disintegrated within 1 hour were marked as “X”. The results are shown in Tables 2 and 3.

  From the results of Table 2 and Table 3, the artificial soil particles of Examples 1 to 16 were compared with the artificial soil particles of Comparative Example 1 and citric acid, which is a component of root acid, and phosphoric acid used as a nutrient. High resistance to It was confirmed that the artificial soil particles according to the present invention can withstand long-term use as a soil substitute.

  The artificial soil particles of the present invention and the artificial soil medium can be used for artificial soil used in plant factories, etc., but as other uses, facility horticultural soil, greening soil, molded soil, soil improver, It can also be used for interior soil.

DESCRIPTION OF SYMBOLS 1 Filler 2 Pore 3 Communication hole 5 Reinforcement material 10 Artificial soil particle 100 Artificial soil culture medium

Claims (8)

  Artificial soil particles comprising a base formed by a plurality of fillers having pores, wherein at least the inside of the base is reinforced with a reinforcing material.   2. The artificial soil particle according to claim 1, wherein the pore has a size of sub nm order to sub μm order, and a communication hole of sub μm order to sub mm order 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 outside and the pores can receive the nutrients from the communication holes. Artificial soil particles   The artificial soil particle according to claim 2 or 3, wherein the filler is combined in a three-dimensional network so that the total volume of the communication hole is larger than the total volume of the pore.   The reinforcing material is at least one substance selected from the group consisting of natural polysaccharides, natural resins, synthetic resins, resin crosslinking agents, inorganic binders, and fibers. Artificial soil particles according to.   The artificial soil particles according to any one of claims 1 to 5, wherein ion exchange capacity is imparted to the pores.   The artificial soil particle according to any one of claims 1 to 6, which has a particle size of 0.2 to 10 mm.   The artificial soil culture medium using the artificial soil particle as described in any one of Claims 1-7.

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