JP2017079688A - Artificial soil particles, method for producing artificial soil particles, and artificial soil culture medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide artificial soil particles having high durability and easy handling while maintaining basic performance as soil.SOLUTION: An artificial soil particle 100 comprising a particulate matter 50 including a fiber 10 and a filler 20 is provided. In the particulate matter 50, the fiber 10 and the filler 20 are bonded by a binder 30 containing a polyolefin resin and a hydrophilic latex. The content ratio (A:B) of the polyolefin resin (A) and the hydrophilic latex (B) contained in the binder 30 is 1:10-10:1 in a weight ratio.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an artificial soil particle having a granular material containing fibers and a filler, a method for producing the artificial soil particle, and an artificial soil medium using the artificial soil particle.

  Artificial soil has been used to grow vegetables in plant factories, but in recent years, the needs for artificial soil have diversified. For example, artificial soil is used to cultivate various plants such as foliage plants and flower buds. It has come to be. Artificial soil is required not only to have excellent basic performance (water retention, fertilizer retention, etc.), but also to be durable and easy to handle. For example, potted products for cultivating houseplants and flower buds indoors using artificial soil are commercially available. Such indoor potted products are not supposed to basically exchange soil once they are used. For this reason, the structure of artificial soil gradually collapses due to changes in water environment due to irrigation and changes in temperature environment, etc., making it difficult to maintain performance such as water retention, fertilizer retention and durability over a long period of time. It may become.

  As artificial soil developed so far, there was a porous artificial soil body in which at least one component of organic matter, inorganic matter, and soil, and solid matter such as gypsum were 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 is obtained by improving the water retention of the artificial soil body by forming pores capable of holding water by partially combining solid substances.

  Moreover, there was a aggregated structure zeolite in which powdery zeolite was bound by a binder made of a water-soluble polymer (see, for example, Patent Document 2). The aggregate structure zeolite of Patent Document 2 is a structure in which zeolite is aggregated to form pores capable of retaining water, thereby increasing the water retention of the aggregate.

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

  As mentioned above, the artificial soil used for cultivation of foliage plants and flower buds naturally has basic performances such as water retention and fertilization, and has high durability and is easy to handle. It is desirable that In this respect, the artificial soil body of Patent Document 1 cannot be said to have sufficient strength because the bonding form of the cured product of the water-soluble urethane polymer is partial. For this reason, the structure of the artificial soil body is destroyed by a change in the moisture environment or the temperature environment, and as a result, the basic performance as soil may be reduced, or fine powder may be generated and difficult to handle.

  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 it can be said that the bonding force between the zeolite particles is sufficient. Absent. When planting plants such as foliage plants using this aggregate structure zeolite, the aggregate structure is destroyed by external pressure, etc., water retention and fertilizer retention is reduced, fine powder etc. are generated and handled May be difficult.

  The present invention has been made in view of the above problems, and provides an artificial soil particle having high durability and easy to handle while maintaining basic performance as soil, and a method for producing the same. With the goal. Moreover, it aims at providing the artificial soil culture medium using the said artificial soil particle.

The characteristic configuration of the artificial soil particles according to the present invention for solving the above problems is as follows:
Artificial soil particles with particulate matter containing fibers and fillers,
In the granular material, the fiber and the filler are bonded with a binder containing a polyolefin-based resin and a hydrophilic latex.

  According to the artificial soil particles of this configuration, since the fibers and fillers contained in the particulate matter are bound by a binder containing a polyolefin resin and a hydrophilic latex, the artificial soil particles have high rigidity due to the polyolefin resin, Appropriate elasticity is imparted by the hydrophilic latex. As a result, for example, when artificial soil particles swell by absorbing moisture during irrigation, even if the artificial soil particles are compacted during planting, the structure of the artificial soil particles will not collapse or be destroyed, It can continue to exhibit basic performance such as water retention and fertilization over a long period of time. And since the fine particle | grains etc. do not generate | occur | produce by maintaining the structure of the artificial soil particle, handling becomes easy.

In the artificial soil particles according to the present invention,
The content ratio (A: B) of the polyolefin resin (A) and the hydrophilic latex (B) contained in the binder is preferably 1:10 to 10: 1 by weight.

  According to the artificial soil particle of this configuration, since the binder that binds the fiber and filler contains the polyolefin resin and the hydrophilic latex in an appropriate content ratio, the artificial soil particle has an excellent balance between rigidity and elasticity. It can be. Polyolefin resin is a material that exhibits water repellency, but since hydrophilic latex has hydrophilicity, if the content is adjusted to the above-mentioned appropriate content ratio, surface stickiness can be prevented without inhibiting the water absorption of artificial soil particles. Is suppressed and the product is easy to use.

The characteristic configuration of the method for producing artificial soil particles according to the present invention for solving the above problems is as follows.
A first mixing step of mixing fiber, filler, and polyolefin resin powder;
A second mixing step of mixing a granulation liquid containing a hydrophilic latex and a thickener in the mixture obtained by the first mixing step;
A granulation step of granulating the mixture obtained by the second mixing step;
A drying step of drying the granulated product obtained by the granulation step;
A heat treatment step for heat treating the granulated product after drying;
It is to include.

  According to the method for producing artificial soil particles of this configuration, easy-to-handle artificial soil particles to which high rigidity by the polyolefin resin and appropriate elasticity by the hydrophilic latex are imparted can be produced. Here, since the polyolefin resin powder and the hydrophilic latex are separately mixed in separate steps, each characteristic can be effectively expressed in the artificial soil particles.

In the method for producing artificial soil particles according to the present invention,
The granulation step is preferably performed by stirring granulation.

  According to the method for producing artificial soil particles of this configuration, artificial soil particles in which fibers and fillers are uniformly mixed in a binder can be produced by performing the granulation step by stirring granulation.

In the method for producing artificial soil particles according to the present invention,
The granulation step is preferably performed by extrusion granulation.

  According to the method for producing artificial soil particles of this configuration, artificial soil particles with little variation in particle size can be produced by performing the granulation step by extrusion granulation.

In the method for producing artificial soil particles according to the present invention,
The drying step is preferably performed at 70 ° C. or lower.

  According to the method for producing artificial soil particles of this configuration, the polyolefin resin powder and hydrophilic latex used as a binder are easier to dry than agar or the like conventionally used as a binder, so that the temperature is relatively low. It can be efficiently dried even at 70 ° C. or lower.

In the method for producing artificial soil particles according to the present invention,
It is preferable to further include a particle size adjustment step of adjusting the particle size distribution of the artificial soil particles to 0.5 to 12 mm.

  According to the method for manufacturing artificial soil particles of this configuration, artificial soil particles whose particle size distribution is adjusted to the appropriate range described above are manufactured, so that an appropriate amount of moisture can be held in the gap between the artificial soil particles. Thus, an artificial soil medium excellent in water retention can be formed.

The characteristic configuration of the artificial soil culture medium according to the present invention for solving the above problems is as follows.
This is because the artificial soil particles described above are used.

  According to the artificial soil culture medium of this structure, since the artificial soil particle of the present invention is used, handling is easy, and even if it is used for a long time, its performance can be maintained. Therefore, the artificial soil medium of this configuration can be suitably used as a growth medium for foliage plants, potted flower buds, etc. with little exchange of the medium.

FIG. 1 is a schematic diagram of artificial soil particles of the present invention. FIG. 2 is a flowchart showing the procedure of the method for producing artificial soil particles of the present invention. FIG. 3 is an example of an enlarged image of the artificial soil particle of the present invention by a microscope.

  Embodiments of the present invention will be described below with reference to FIGS. However, the present invention is not intended to be limited to the configurations described in the following description and drawings.

<Artificial soil particles>
FIG. 1 is a schematic diagram of an artificial soil particle 100 of the present invention. The artificial soil particle 100 includes a granular material 50 including the fiber 10 and the filler 20, and in the granular material 50, the fiber 10 and the filler 20 are bonded by a binder 30.

  The fiber 10 is preferably an organic fiber, and any of naturally-derived fibers, regenerated fibers, semi-synthetic fibers, and synthetic fibers can be used. However, it is preferable to use hydrophilic fibers so that the artificial soil particles 100 can maintain a certain level of water retention. Preferred hydrophilic fibers include cellulose, cotton, wool, etc. for naturally derived fibers, rayon, etc. for regenerated fibers, acetate, etc. for semi-synthetic fibers, and vinylon, urethane, nylon, etc. for synthetic fibers. It is done. Among these hydrophilic fibers, cellulose, cotton, and vinylon have a white appearance and have good appearance, good coloration, and are inexpensive in price. Particularly preferably used as a material. The fiber 10 may be a mixture of a plurality of types of fibers.

  As the filler 20, an inorganic filler is preferably used, and an inorganic porous body such as a porous mineral, an inorganic foam, and an inorganic porous aggregate is preferable. Examples of the porous mineral include diatomaceous earth, perlite, vermiculite, and pumice. Examples of the inorganic foam include glass foam, shale foam, and shirasu balloon. Examples of the inorganic porous aggregate include foamed concrete and foamed brick. Among these inorganic porous bodies, diatomaceous earth and pearlite, which are porous minerals, are excellent in water retention, have a good appearance because they have a white appearance, have good colorability, and are inexpensive. Since it is also inexpensive, it is particularly preferably used as a material for artificial soil used in large quantities. When it is desired to increase the fertilizer of the artificial soil particle 100, a mineral having ion exchange ability is used as the filler 20. Examples of minerals having ion exchange ability include cation exchange minerals (eg, smectite minerals such as montmorillonite, bentonite, beidellite, hectorite, saponite, stevensite, mica minerals, vermiculite, zeolite), anion exchange minerals. (For example, natural layered double hydroxides having double hydroxides as main skeletons such as hydrotalcite, manaceite, pyroaulite, sjoglenite, patina, synthetic hydrotalcite and hydrotalcite-like substances, allophane, imogolite, And clay minerals such as kaolin). The filler 20 may be a mixture of two or more. For example, if diatomaceous earth and zeolite are selected as the filler 20 and a mixture of both is used at an appropriate blending ratio, the artificial soil particle 100 having both water retention and fertilizer retention while being relatively inexpensive. Can be designed.

  As the binder 30 for bonding the fiber 10 and the filler 20, a mixture of a plurality of types of resins having different characteristics is used. In the present invention, the binder 30 includes a polyolefin resin and a hydrophilic latex. By selecting such a combination of resins, the granular material 50 constituting the artificial soil particle 100 can be imparted with appropriate rigidity by the polyolefin-based resin and elasticity by the hydrophilic latex.

  The polyolefin-based resin is obtained by melting the polyolefin-based resin powder added in the first mixing step of “artificial soil particle manufacturing method” described later in a heat treatment step, and then cooling and curing. Examples of the polyolefin resin powder include resin powder made of polyolefin resin such as polyethylene resin (PE) and low density polyethylene resin (LDPE). Resin powder made of polyolefin resin is excellent in strength and is therefore suitable for use as artificial soil particles.

  The hydrophilic latex is natural latex, polychloroprene latex, styrene-butadiene latex, styrene-butadiene-vinylpyridine latex, acrylonitrile-butadiene latex, carboxyl-modified styrene-butadiene latex, carboxyl-modified styrene-butadiene-vinylpyridine latex, carboxyl-modified acrylonitrile. -Butadiene latex, carboxyl modified methyl methacrylate-butadiene latex, acrylate latex, water-based polyurethane resin and the like. Of these hydrophilic latexes, acrylate latex is preferably used.

  The properties (particularly mechanical properties) of the artificial soil particles 100 are affected by the content ratio of the polyolefin-based resin and the hydrophilic latex. If the content ratio is in an appropriate range, the artificial soil particle 100 has a good balance between rigidity and elasticity. For example, the artificial soil particle 100 absorbs moisture during irrigation and swells, or artificially when planting. Even if the soil particles 100 are compacted, the structure of the artificial soil particles 100 is not destroyed or destroyed, and the basic performance such as water retention and fertilizer retention can be maintained over a long period of time. Moreover, since the structure of the artificial soil particle 100 does not collapse and fine powder or the like is not generated, handling becomes easy. Here, when the content of the polyolefin resin in the binder 30 is A and the content of the hydrophilic latex is B, the content ratio (A: B) of the polyolefin resin and the hydrophilic latex is 1 by weight. : 10 to 10: 1, preferably 1: 5 to 5: 1. When the content ratio is smaller than 1:10, that is, when the polyolefin-based resin is insufficient with respect to the hydrophilic latex, the artificial soil particles 100 become too soft to stably support the cultivated plant. . When the content ratio is larger than 10: 1, that is, when the polyolefin-based resin is excessive with respect to the hydrophilic latex, the water absorption of the artificial soil particles 100 is deteriorated, so that the watering frequency is increased and the handling is inconvenient. It becomes. The artificial soil particle 100 whose content ratio is adjusted to the above range is a product that is easy to use because surface stickiness is suppressed without inhibiting water absorption.

  The granular material 50 in a state where the fiber 10 and the filler 20 are bonded by the binder 30 can be used as it is as the artificial soil particle 100 of the present invention, but a film is provided on the surface of the granular material 50, It is also possible to coat the surface. For example, when a porous membrane (not shown) through which moisture can pass is provided on the surface of the granular material, artificial soil particles capable of controlling moisture absorption and release characteristics according to the surrounding moisture environment can be designed. In addition, if the surface of the granular material is coated with an anti-discoloring agent, deterioration due to moisture, ultraviolet rays, friction, etc. can be prevented. If artificial soil particles are colored with a coloring agent, discoloration, discoloration will occur. , Fading and the like can be prevented.

  The granular material 50 is adjusted so that the total blending amount of the fiber 10 and the filler 20 and the blending amount of the binder 30 is 2: 1 to 30: 1, preferably 3: 1 to 20: 1, in a weight ratio. The When the weight ratio is smaller than 2: 1 (that is, when the total blending amount of the fiber 10 and the filler 20 is less than twice the blending amount of the binder 30), the blending amount of the binder 30 becomes excessive. The fibers 10 and the fillers 20 are buried in the binder 30, and the water retention and fertilizer retention of the artificial soil particles 100 finally obtained may be reduced. On the other hand, when the weight ratio is larger than 30: 1 (that is, when the total blending amount of the fiber 10 and the filler 20 exceeds 30 times the blending amount of the binder 30), the blending amount of the binder 30 is insufficient. The binding force between the fiber 10 and the filler 20 is insufficient, and the artificial soil particle 100 finally obtained is likely to collapse.

<Method for producing artificial soil particles>
In the conventional methods for producing artificial soil particles, a granulating liquid containing water, agar, potassium alginate, and a polyolefin resin emulsion has been used when granulating fibers and fillers. Among these, agar is added to impart wettability to the artificial soil particles, but it was necessary to heat the granulation liquid to 80 ° C. in order to dissolve the agar in the granulation liquid. On the other hand, in the present invention, the granulation liquid does not contain agar, and instead using hydrophilic latex, high wettability is imparted to the artificial soil particles while eliminating the need for heating the granulation liquid. To do.

  The artificial soil particles of the present invention are present in a granular material in a state where fibers and fillers are mixed with each other, and are bonded by a binder while maintaining the mixed state, so that the shape as particles is maintained. In order to obtain such artificial soil particles, in the method for producing artificial soil particles of the present invention, a first mixing step, a second mixing step, a granulating step, a drying step, and a hardening step are executed. Through these series of steps, artificial soil particles having excellent balance between rigidity and elasticity and easy handling can be produced while maintaining basic performance as soil. Hereinafter, based on the flowchart of FIG. 2, the manufacturing method of the artificial soil particle of this invention is demonstrated. The symbol “S” shown in FIG. 2 means a step.

[First mixing step]
First, fibers, fillers, and polyolefin resin powder are mixed (S1: first mixing step). In the first mixing step, the fibers, fillers, and polyolefin resin powder are put into a stirrer (granulator) and stirred so that the raw materials are sufficiently mixed. That is, in the first mixing step, solid raw materials are mixed among the raw materials of the artificial soil particles. The order in which the solid raw materials are charged into the stirrer may be all at the same time or different. For example, the fibers and fillers may be added and stirred, and the polyolefin resin powder may be added after both have become sufficiently familiar. When mixing the polyolefin resin powder, it is not necessary to add a surfactant or the like, so that the artificial soil particles finally obtained do not generate foaming even when wet due to irrigation or the like, and are easy to use It will be a thing. As the fibers, fillers, and polyolefin resin powders, resin powders composed of organic fibers, inorganic fillers, and polyolefin resins described in the above-mentioned “artificial soil particles” can be used. The polyolefin resin powder having a 50% particle size range of 15 to 355 μm, preferably 75 to 180 μm is used. Here, the x% -containing particle size range is a particle size range in which x% of the total number of particles is included with the median particle size as the median value in the particle size distribution of the resin powder in which the median particle size is indicated. means. For example, when the median particle size is 20 μm, the 50% particle size range can be 15 to 35 μm, and the 80% particle size range can be 10 to 40 μm. When the median particle size is 130 μm, the 50% containing particle size range can be 75 to 180 μm, and the 80% containing particle size range can be 40 to 250 μm. When the median particle size is 250 μm, the 50% content particle size range can be 180-355 μm, and the 80% content particle size range can be 50-500 μm. In order to set the 50% particle size range to 15 to 355 μm, three types of polyolefin resin powders having a median particle size of 20 μm, 130 μm, and 250 μm may be mixed at an appropriate blending ratio. Further, as the characteristics of the polyolefin resin powder, the melt flow rate (temperature: 190 ° C., load: 2.16 kgf) measured in accordance with JIS K7210 is 50 g / 10 minutes or more, preferably 58 g / 10 minutes or more. To do. By using polyolefin resin powder having such a melt flow rate, it is possible to effectively increase the binding strength of fibers and fillers, while maintaining the basic performance of the artificial soil particles finally obtained while maintaining durability. Can be improved. The blending amount of the solid raw material takes into consideration the blending amount of the hydrophilic latex described later, and the total blending amount of the fiber and filler and the blending amount of the polyolefin resin powder are 1: 1 to 100: 1 by weight ratio, preferably Is adjusted to be 3: 1 to 30: 1.

[Second mixing step]
Next, a granulation liquid is mixed with the mixture of the fiber, filler, and polyolefin resin powder obtained in the first mixing step (S2: second mixing step). The granulating liquid contains a hydrophilic latex and a thickener. That is, in the second mixing step, the remaining liquid raw material is mixed among the raw materials of the artificial soil particles. As the hydrophilic latex, it is preferable to use the acrylate latex described in the item “Artificial soil particles” described above. The acrylate latex is added in the form of a dispersion dispersed in an appropriate solvent. Thickeners are prepared by dissolving or dispersing water-soluble polymers such as polyacrylates such as potassium polyacrylate and sodium polyacrylate, polysaccharides such as carboxymethyl cellulose, polyvinyl alcohol, and polyvinyl acetate in water. Is preferred. In addition, additives such as antibacterial agents, fungicides, deodorants, antioxidants, dyes, pigments, and fragrances, and solvents such as water and alcohol for viscosity adjustment may be added to the granulation liquid. it can. The blending amount of the granulating liquid is set in consideration of the amount of polyolefin resin powder used in the first mixing step. Here, in the artificial soil particles finally obtained, if the content of the polyolefin resin contained in the binder is A and the content of the hydrophilic latex is B, the content ratio of the polyolefin resin and the hydrophilic latex ( A: B) is adjusted to a weight ratio of 1:10 to 10: 1, preferably 1: 5 to 5: 1. In order to obtain such a content ratio, the content of the hydrophilic latex in the granulation liquid is set to 1.0% by weight or more, and the granulation liquid is mixed with 100% by weight of a fiber, filler, and polyolefin resin powder. What is necessary is just to add 100-500 weight part with respect to a part. Thereby, the artificial soil particle excellent in the balance of rigidity and elasticity can be prepared. Such artificial soil particles are products that are easy to use because their surface stickiness is suppressed without hindering their water absorption.

[Granulation process]
After the second mixing step, the obtained mixture is granulated (S3: granulation step). The granulation process is typically the following two granulation methods. A 1st granulation process is stirring granulation which granulates stirring a raw material (S3-1). Agitation granulation is performed by using the stirrer used in the first mixing step and the second mixing step and continuing the stirring of the mixture as it is. In this case, the fibers and fillers mixed in the first mixing step are gradually granulated while entraining the granulation liquid mixed in the second mixing step, and the original form of artificial soil particles (granular material) is generated. As described above, in the agitation granulation, the fibers and fillers contained in the raw material are bound by the binder while the raw material is adjusted to a particle shape by a stirrer.

  A 2nd granulation process is extrusion granulation which granulates while extruding a raw material (S3-2). In extrusion granulation, the raw material mixture obtained in the first mixing step and the second mixing step is filled into an extrusion granulator, the mixture is extruded from the nozzle of the extrusion granulator, and the extruded mixture is further sized appropriately. It is cut and molded into the original shape of artificial soil particles (granular material). Thus, in extrusion granulation, since the mixture is formed (granulated) using a mold, artificial soil particles having a uniform size and shape can be produced.

  When the fertilizer component is supported on the artificial soil particles, the granulation step is performed using a granulation liquid containing the fertilizer component. In this case, a fertilizer component may be added to the granulation liquid used in the second mixing step. When the granulation step is performed using a granulation liquid containing a fertilizer component, the fertilizer component adheres to the fibers and fillers, and the artificial soil particles finally obtained are those in which the fertilizer component is retained from the surface to the inside. When a plant is cultivated using artificial soil particles in which this fertilizer component is retained, the fertilizer component is first eluted from the surface of the granule by irrigation, root acid of the plant, etc., and then the fertilizer component retained inside the granule Elutes gradually. Such artificial soil particles having a sustained release property of fertilizer are suitable as a growth medium for foliage plants and potted flower buds that are cultivated over a long period of time. In addition, when the material which has ion exchange ability is used as a filler, since the fertilizer component adheres to a fiber and a filler, since it is carry | supported by the ion exchange to a filler, the sustained release period of a fertilizer can be further extended. Incidentally, since the structure of the artificial soil particle of the present invention is fixed by the curing process described later, the structure as the artificial soil particle is maintained even after the fertilizer component is lost. Therefore, the structure of the artificial soil particles is prevented from collapsing to generate fine powder, and the handling becomes easy.

[Drying process]
Next, the granulated product obtained by the granulation step is dried (S4: drying step). The drying temperature of the granulated product in the drying step is preferably lower than the melting temperature of the polyolefin resin. For example, when the drying process is performed using a blow type shelf dryer that performs drying while sending moisture generated during drying, the drying temperature is set to 40 to 90 ° C, preferably 60 to 80 ° C, The drying time is set to 5 to 30 hours, preferably 6 to 16 hours. If the drying temperature is lower than 40 ° C, or if the drying time is shorter than 5 hours, excessive moisture remains in the granulated product, so even if the granulated product is heat-treated at 100 ° C or higher in the next heat treatment step, The polyolefin resin contained in the binder cannot sufficiently bond the fibers and fillers, and as a result, it becomes difficult to obtain performances such as durability and strength necessary for the artificial soil particles. On the other hand, when the drying temperature is higher than 90 ° C. or when the drying time is longer than 30 hours, there is a possibility that the polyolefin resin contained in the binder melts and flows out and blocks the voids in the artificial soil particles. Artificial soil particles in which the voids are blocked cannot easily enter water, so that good water retention cannot be obtained.

[Heat treatment process]
Next, it heat-processes with respect to the granulated material which the drying process was completed (S5: heat processing process). The heat treatment temperature of the granulated product in the heat treatment step is adjusted to a temperature higher than the melting temperature (melting point) of the binder in order to reliably bond the fiber and filler with the binder. For example, a polyolefin resin (polyethylene resin or low density polyethylene resin) which is one component of the binder has a melting point of 100 to 110 ° C. and a melt flow rate of 50 to 80 g / 10 min. On the other hand, hydrophilic latex (acrylate latex), which is another component of the binder, is sufficiently removed from the moisture in the previous drying step, so that the hydrophilic latex (solid content) after removal of moisture contacts the fiber and filler. High adhesive strength can be obtained by simply doing. Therefore, for example, when a mixture of polyethylene resin and acrylate latex is used as the binder, the heat treatment temperature is preferably 100 to 150 ° C. After the binder is fused to the fiber and filler by heat treatment, the granulated product is cooled, the binder is solidified, and the fiber and filler are fixed. Thereby, the granulated material containing a fiber, a filler, and a binder is cured while maintaining the particle shape. As another curing step, for example, when the binder contains a crosslinkable resin that is crosslinked (cured) by heating or light irradiation, the granulated product containing fibers, fillers, and binders is formed by thermosetting reaction or photocrosslinking reaction. Can be cured to shape.

  In the granular material obtained by the heat treatment step, the fibers and fillers contained in the granular material are bound by a binder containing a polyolefin-based resin and a hydrophilic latex, so that the artificial soil particles have high rigidity due to the polyolefin-based resin. Appropriate elasticity is imparted by the hydrophilic latex. As a result, for example, when artificial soil particles swell by absorbing moisture during irrigation, even if the artificial soil particles are compacted during planting, the structure of the artificial soil particles will not collapse or be destroyed, The basic performance such as water retention and fertilization can be maintained over a long period of time. And since the fine particle | grains etc. do not generate | occur | produce by maintaining the structure of the artificial soil particle, handling becomes easy.

(Granularity adjustment process)
When an artificial soil medium is constructed using artificial soil particles, if the particle size distribution of the artificial soil particles is moderately aligned, not only the artificial soil particles but also the gaps formed between the artificial soil particles Moisture can be retained. Therefore, when configuring an artificial soil medium, the particle size distribution of the artificial soil particles is adjusted to 0.5 to 12 mm, preferably 0.7 to 6 mm (S6: particle size adjusting step). When many artificial soil particles having a particle size smaller than 0.5 mm are included, the gap formed between the artificial soil particles becomes small, and moisture (easy-to-use water) that can be used by cultivated plants is strongly adsorbed in the gap. Air permeability decreases. As a result, oxygen cannot be sufficiently supplied to the roots of cultivated plants, and root rot may occur. On the other hand, when many artificial soil particles having a particle diameter larger than 12 mm are included, the gap formed between the artificial soil particles becomes large, the force for retaining moisture in the gap is weakened, and water retention is reduced. Therefore, it is necessary to increase the frequency of irrigation to the cultivated plant, and human labor is required when cultivating foliage plants, potted flower buds and the like. The particle size adjustment step can be performed by sieving or the like, but in the above granulation step, the particle size distribution is adjusted to approximately 0.5 to 12 mm when generating a granulated product containing fibers, fillers, and binders. If it can be done, it is not necessary to perform the particle size adjustment step again. In this case, the granulation step also serves as the particle size adjustment step. Artificial soil particles whose particle size distribution is appropriately adjusted can be suitably used as a growth medium for foliage plants and potted flower buds.

  According to the method for producing artificial soil particles of the present invention, artificial soil particles (Examples 1 to 6) in which fibers and fillers are bonded with a binder containing a polyolefin resin (powder type) and a hydrophilic latex (liquid type) are produced. did. In addition, for comparison, artificial soil particles (Comparative Example 1) in which fibers and fillers are combined with a binder that contains a polyolefin-based resin but does not contain a hydrophilic latex, and fibers and fillers that contain a hydrophilic latex but are polyolefin-based Artificial soil particles (Comparative Example 2) formed by binding with a binder containing no resin were produced. And the characteristic of each artificial soil particle concerning an Example and a comparative example was evaluated.

In addition, the following was used as a raw material of artificial soil particles.
Fiber: Cellulose fiber (KC Flock (registered trademark) W-100GK, manufactured by Nippon Paper Industries Co., Ltd.)
Filler: Diatomaceous earth (Radiolite (registered trademark) # 300, Showa Chemical Industry Co., Ltd.)
Polyolefin resin powder: polyethylene resin powder (PR1030C60PASS, manufactured by Tokyo Ink Co., Ltd., medium particle size: 130 μm, 50% containing particle size range: 75 to 180 μm, 80% containing particle size range: 40 to 250 μm, melt flow rate : 58g / 10min)
Hydrophilic latex: Acrylate latex (Nipol LX851C, manufactured by Nippon Zeon Co., Ltd., medium particle size: 250 μm, glass transition temperature: 15 ° C.)
・ Water: Tap water ・ Thickener: Potassium alginate (Kimika Co., Ltd.)
Agar (MS-700, manufactured by Marine Science Co., Ltd.)

[Example 1]
According to the composition of raw materials shown in Table 1 (unit: parts by weight), the solid raw materials of artificial soil particles were put into a stirring and mixing granulator (MGS12 type manufactured by G-Labo Co., Ltd.), stirred and rolled for several minutes, A granulation liquid containing a liquid raw material was added, and the mixture was further stirred and rolled for about 10 minutes to form a granulated body. That is, in Example 1, artificial soil particles were produced by stirring granulation. The granulated body is dried with hot air of 60 to 80 ° C., and further heat treated at 130 ° C. for 2 hours to melt the polyethylene resin powder to bind cellulose fibers and diatomaceous earth, and then cool this to cool the Artificial soil particles were obtained.

[Example 2]
According to the composition of raw materials shown in Table 1 (unit: parts by weight), a granulated liquid containing a solid raw material and a liquid raw material was prepared, and artificial soil particles were produced by the same stirring granulation as in Example 1. The granulated material obtained by the agitation granulation was treated under the same drying and heat treatment conditions as in Example 1 and cooled to obtain artificial soil particles of Example 2.

Example 3
According to the composition of raw materials shown in Table 1 (unit: parts by weight), a granulated liquid containing a solid raw material and a liquid raw material was prepared, and artificial soil particles were produced by the same stirring granulation as in Example 1. The granulated material obtained by stirring granulation was treated under the same drying conditions and heat treatment conditions as in Example 1, and cooled to obtain artificial soil particles of Example 3.

Example 4
According to the composition of raw materials shown in Table 1 (unit: parts by weight), a granulated liquid containing a solid raw material and a liquid raw material was prepared, and artificial soil particles were produced by the same stirring granulation as in Example 1. The granulated material obtained by the agitation granulation was treated under the same drying and heat treatment conditions as in Example 1 and cooled to obtain artificial soil particles of Example 4.

Example 5
According to the composition of raw materials shown in Table 1 (unit: parts by weight), a granulated liquid containing a solid raw material and a liquid raw material was prepared, and artificial soil particles were produced by the same stirring granulation as in Example 1. The granulated material obtained by stirring granulation was treated under the same drying conditions and heat treatment conditions as in Example 1, and cooled to obtain artificial soil particles of Example 5.

Example 6
According to the composition of raw materials shown in Table 1 (unit: parts by weight), a granulated liquid containing a solid raw material and a liquid raw material was prepared, and artificial soil particles were produced by the same stirring granulation as in Example 1. The granulated material obtained by stirring granulation was treated under the same drying conditions and heat treatment conditions as in Example 1, and cooled to obtain artificial soil particles of Example 6.

[Comparative Example 1]
According to the composition of raw materials shown in Table 1 (unit: parts by weight), a granulated liquid containing a solid raw material and a liquid raw material was prepared, and artificial soil particles were produced by the same stirring granulation as in Example 1. The granulated material obtained by the agitation granulation was treated under the same drying conditions and heat treatment conditions as in Example 1 and cooled to obtain artificial soil particles of Comparative Example 1. The artificial soil particle of Comparative Example 1 uses polyethylene resin powder as a binder but does not use acrylate latex, and further uses agar.

[Comparative Example 2]
According to the composition of raw materials shown in Table 1 (unit: parts by weight), a granulated liquid containing a solid raw material and a liquid raw material was prepared, and artificial soil particles were produced by the same stirring granulation as in Example 1. The granulated material obtained by stirring granulation was treated under the same drying conditions and heat treatment conditions as in Example 1, and then cooled to obtain artificial soil particles of Comparative Example 2. The artificial soil particles in Comparative Example 2 use acrylate latex as a binder but do not use polyethylene resin powder.

<Structure of artificial soil particles>
As an example of the structure of the artificial soil particles of the present invention, FIG. 3 shows an enlarged image of the artificial soil particles according to Example 6 with a microscope. The artificial soil particles of the present invention are solidified in a state where the polyethylene resin powder, which is one component of the binder, is melted. As a result, the polyethylene resin is scattered in islands in the artificial soil particles (dark regions in the image). ), And it was confirmed that the fiber and the filler were firmly bonded. The acrylate latex, which is another component of the binder, has a very small particle size and cannot be clearly confirmed by a microscopic image, but is presumed to be scattered throughout the artificial soil particles.

<Characteristic evaluation of artificial soil particles>
About the artificial soil particles of Examples 1 to 6 and Comparative Examples 1 and 2, water retention and strength (compressive strength) were evaluated. For water retention, a cup with a hole having a large number of holes at the bottom is filled with 100 cc of artificial soil particles having a particle diameter of 2 to 4 mm, and 50 cc of water is poured into the cup, and the amount of water discharged from the bottom of the cup. Water retention was evaluated more. Regarding strength, artificial soil particles having a particle diameter of 4 to 6 mm were immersed in water to obtain a saturated water-containing state, one of the artificial soil particles was compressed, and the state of destruction was confirmed. The evaluation criteria for water retention and strength were evaluated in five levels: poor (level 1), slightly poor (level 2), standard (level 3), slightly good (level 4), and good (level 5). Table 2 shows the results of the characteristic evaluation.

  The artificial soil particles of Examples 1 to 6 containing a polyolefin-based resin and a hydrophilic latex as a binder are excellent in water retention and strength balance, and have high durability while maintaining basic performance as soil. It was shown that On the other hand, the artificial soil particles of Comparative Example 1 containing polyethylene resin powder as a binder but not containing acrylate latex did not provide sufficient performance, and were particularly poor in water retention. Sufficient performance was not obtained for the artificial soil particles of Comparative Example 2 containing acrylate latex as a binder but no polyethylene resin powder, and the strength was particularly inferior. Thus, the artificial soil particles of Comparative Example 1 and Comparative Example 2 were unsuitable for artificial soil media for cultivation of foliage plants and flower buds used for a long time.

  The method for producing artificial soil particles according to the present invention is preferably used for producing artificial soil particles used in a growth medium for indoor houseplants and potted flower buds, but is cultivated in a plant factory or the like. It can also be used for the purpose of producing artificial soil particles to be used as a growth medium.

10 Fiber 20 Filler 30 Binder 50 Granules 100 Artificial soil particles

Claims (8)

Artificial soil particles with particulate matter containing fibers and fillers,
In the granular material, the fiber and the filler are artificial soil particles bonded with a binder containing a polyolefin-based resin and a hydrophilic latex.   The artificial ratio according to claim 1, wherein a content ratio (A: B) of the polyolefin resin (A) and the hydrophilic latex (B) contained in the binder is 1:10 to 10: 1 by weight. Soil particles. A first mixing step of mixing fiber, filler, and polyolefin resin powder;
A second mixing step of mixing a granulation liquid containing a hydrophilic latex and a thickener in the mixture obtained by the first mixing step;
A granulation step of granulating the mixture obtained by the second mixing step;
A drying step of drying the granulated product obtained by the granulation step;
A heat treatment step for heat treating the granulated product after drying;
For producing artificial soil particles.   The said granulation process is a manufacturing method of the artificial soil particle of Claim 3 performed by stirring granulation.   The method for producing artificial soil particles according to claim 3, wherein the granulation step is performed by extrusion granulation.   The said drying process is a manufacturing method of the artificial soil particle as described in any one of Claims 3-5 implemented at 70 degrees C or less.   The method for producing artificial soil particles according to any one of claims 3 to 6, further comprising a particle size adjustment step of adjusting the particle size distribution of the artificial soil particles to 0.5 to 12 mm.   The artificial soil culture medium using the artificial soil particle of Claim 1 or 2.

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