JP2017099341A - Manufacturing method of artificial soil grains, and artificial soil grains - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of artificial soil grains with improved water holding capacity.SOLUTION: A manufacturing method of artificial soil grains includes: a kneading process of mixing at least fiber and binder; and an extrusion/granulation process of extruding a kneaded product 40 obtained in the kneading process and granulating the product. In the extrusion/granulation process, the kneaded product 40 is extruded from a screen die 33 at the pressure of 5 to 30 kg/cm, and the kneaded product 40 extruded from the screen die 33 is cut off to create 1 to 380 pieces of artificial soil grains 50 per 1 second. In the kneading process, a mixture ratio between the fiber and the binder is 55:45 to 95:5 at a weight ratio.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a method for producing artificial soil particles containing fibers and a binder, and artificial soil particles provided with a fiber mass formed by collecting fibers.

  Artificial soil has been used for indoor greening and vegetable cultivation in plant factories, but in recent years, the need for artificial soil has diversified. For example, artificial soil is used to produce various types of ornamental plants and flower buds. Plants are being cultivated.

  In the development of artificial soil, a function capable of appropriately maintaining and managing water retention is required while achieving the same plant growth ability as natural soil. In particular, it is necessary for an artificial soil medium to absorb and retain an appropriate amount of water in order to realize an optimal cultivation schedule according to the type of plant.

  As an example of artificial soil imparted with functionality, Patent Document 1 discloses an artificial aggregate in which particles made of an inorganic material are entangled with an organic material made of organic plant fibers and the like, and solidified in a granular form by a binder. Has been proposed.

JP 2001-204245 A

  In the artificial aggregate of Patent Document 1, a binder is added to an intermediate material obtained by mixing a fibrous organic material and an inorganic material, and the artificial aggregate is obtained by stirring granulation. Forming. Thus, in the conventional artificial soil particles including Patent Document 1, the agitation granulation method is used as a step of granulating raw materials. In the agitation granulation method, particles are grown by adding other materials while rotating the granulator to agitate the particles made of the raw material fibers and the like. Thereby, artificial soil particles having a desired particle diameter are obtained. However, in the artificial soil particles formed using the agitation granulation method, the fibers contained in the particles are present while maintaining the original shape in a randomly oriented state. Since the gap formed between the fibers reflects the shape of the fiber as it is, the gap has a relatively simple structure when the fiber maintains the original shape (for example, when the fibers are less crimped). It becomes. Here, in the artificial soil, for example, high water retention is required in order to realize convenience not found in natural soil, such as reducing the number of times of watering. However, in the conventional artificial soil particles that do not have complicated complex voids, even if moisture is once taken into the voids, the moisture easily leaks to the outside through the communication holes that lead from the voids to the outside. Thus, the conventional artificial soil particles have room for improvement in terms of water retention.

  The present invention has been made in view of the above problems, and provides a method for producing artificial soil particles with improved water retention, and further provides artificial soil particles with improved water retention. To do.

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 kneading step of mixing at least fibers and a binder;
An extrusion granulation step of extruding and granulating the kneaded product obtained in the kneading step;
It is to include.

  According to the method for producing artificial soil particles of this configuration, the fibers and the binder are mixed in the kneading step, so that the fibers are randomly oriented in the kneaded product. Subsequently, in the extrusion granulation step, pressure is applied to the kneaded product, and the fibers in the kneaded product are compressed and contracted. Then, the fibers in the kneaded product are bound by a binder in a state where they are shrunk and entangled to form a fiber lump. Since the fibers in the fiber lump are intertwined in a complicated manner, the voids formed between the fibers have a dense and complicated structure. For this reason, the communication hole leading from the gap to the outside also has a complicated structure. Therefore, when moisture is taken into the artificial soil particles, the moisture is attached or adsorbed to the voids and the communication holes and stays in the artificial soil particles, and water leaked by gravity (gravity water) is reduced. As a result, the water retention of artificial soil particles is improved. Further, since the water retention improves, the artificial soil particles can continuously supply water to the plant over a long period of time, so that the number of watering operations can be greatly reduced.

In the method for producing artificial soil particles according to the present invention,
In the extrusion granulation step, the kneaded product is extruded from a screen die at a pressure of 5 to 30 kg / cm ² , and the kneaded product extruded from the screen die is cut to obtain 1 to 380 artificial soil particles per second. It is preferable to produce.

  According to the method for producing artificial soil particles of this configuration, in the extrusion granulation step, the pressure applied to the kneaded product is set to an appropriate range, so the fibers in the kneaded product are compressed with an appropriate bending condition. . Thereby, fibers can be intertwined in a complicated manner, and the water retention of artificial soil particles can be improved. In addition, since the number of kneaded materials to be cut per second is set within an appropriate range, the production of artificial soil particles with high water retention having a size and shape suitable for cultivation of foliage plants and flower buds Can do.

In the method for producing artificial soil particles according to the present invention,
In the kneading step, the mixing ratio of the fiber and the binder is preferably 55:45 to 95: 5 by weight.

  According to the method for producing artificial soil particles of this configuration, in the kneading step, since the mixing ratio of the fiber and the binder is set to an appropriate range, the density of the fibers contained in the artificial soil particles is within a certain range. Become. For this reason, the space | gap formed between fibers also becomes a size of a fixed range. As a result, dense voids are uniformly formed in the artificial soil particles, and the water retention of the artificial soil particles can be improved.

In the method for producing artificial soil particles according to the present invention,
In the kneading step, it is preferable to further add an inorganic filler.

  According to the method for producing artificial soil particles of this configuration, artificial soil particles having the properties of an inorganic filler can be produced by adding an inorganic filler in addition to fibers and a binder in the kneading step. For example, when using a hygroscopic material as an inorganic filler, when water is added to the raw material of artificial soil particles and kneaded, the inorganic filler absorbs moisture with the inorganic filler adhering to the fiber surface, and kneaded. Things become viscous. As a result, the fibers tend to be bundled together while shrinking, and a fiber lump can be easily formed.

In the method for producing artificial soil particles according to the present invention,
In the kneading step, when the inorganic filler is added, it is preferable to further add 1 to 30 parts by weight of a thickener with respect to 100 parts by weight of the inorganic filler.

  According to the method for producing artificial soil particles of this configuration, the viscosity of the kneaded product can be improved by further adding an appropriate amount of a thickener in addition to the inorganic filler. As a result, the fibers in the kneaded product are more easily united while shrinking.

In the method for producing artificial soil particles according to the present invention,
The mixing ratio of the fiber and the inorganic filler is preferably 10:90 to 90:10 by weight.

  According to the method for producing artificial soil particles of this configuration, since the mixing ratio of the fiber and the inorganic filler is set to an appropriate range, an appropriate amount of the inorganic filler adheres to the surface of the fiber and separates the fibers from each other. Thus, a fiber lump is formed while maintaining an appropriate density (that is, voids). As a result, artificial soil particles having a porosity and pore volume suitable for the cultivation of foliage plants and flower buds can be produced.

The characteristic configuration of the artificial soil particles according to the present invention for solving the above problems is as follows:
Artificial soil particles having a fiber mass formed by collecting fibers,
The fibers constituting the fiber lump are bound by a binder in a state of being entangled and entangled,
The porosity is 60-70%,
The pore volume is in the range of 0.9 to 1.4 mL / g.

  According to the artificial soil particles of this configuration, the fibers constituting the fiber lump are bound by the binder in a tangled state, so that there are dense and complicated interstices between the fibers of the fiber lump. It is formed. As a result, the communication hole leading from the gap to the outside also has a complicated structure. When moisture is taken into artificial soil particles having such a fiber lump, the water is attached or adsorbed to the voids and communication holes and stays in the artificial soil particles, reducing the water leaked by gravity (gravity water). Is done. As a result, the water retention of artificial soil particles is improved. Further, since the water retention improves, the artificial soil particles can replenish water to the plant over a long period of time, so that the number of watering operations can be greatly reduced.

FIG. 1 is a schematic diagram of artificial soil particles according to the present invention. FIG. 2 is an explanatory diagram of an extrusion granulation step of artificial soil particles performed using an extrusion granulator. FIG. 3 is an enlarged view (photograph) of the artificial soil particles according to the example and the artificial soil particles according to the comparative example. FIG. 4 is an enlarged view of a cross section of the artificial soil particles according to the example obtained by the X-ray CT analysis and the artificial soil particles according to the comparative example.

  Hereinafter, an embodiment relating to a method for producing artificial soil particles and an artificial soil particle according to the present invention will be described with reference to the drawings. For convenience of explanation, the artificial soil particles of the present invention will be described first, and then the method for producing the artificial soil particles will be described. However, the present invention is not intended to be limited to the configurations described in the embodiments and drawings described below.

<Artificial soil particles>
FIG. 1 is a schematic diagram of artificial soil particles 50 according to the present invention. FIG. 1A is a schematic diagram of the entire artificial soil particle 50, and FIG. 1B is an enlarged view of a region A1 surrounded by a broken-line circle in the artificial soil particle 50 of FIG. As shown to Fig.1 (a), the artificial soil particle 50 has the fiber lump 10 formed by granulating the fiber 1. As shown in FIG. The fiber lump 10 is formed as a granular material that is bound by a binder in a state where the fibers 1 are contracted and entangled. In FIG. 1, the binder is not shown, but the entire fiber 1 is fixed by the binder in a state where the contact portions of the fibers 1 are consolidated through the binder or the fibers 1 are entangled with each other. It is tied.

  There are voids 2 between the fibers 1, and the voids 2 can absorb and retain moisture. As shown in FIG. 1A, since the fibers 1 of the fiber lump 10 are intertwined in a complicated manner, the gaps 2 formed between the fibers 1 have a dense and complicated structure. For this reason, the communication hole which leads from the space | gap 2 to the exterior (outside of particle | grains) is also comprised complicated. The communication hole is formed by connecting the gaps 2, and another gap 2 existing around one gap 2 is a communication hole. Therefore, the gap 2 also serves as a communication hole. Due to such a structure, when moisture is taken into the artificial soil particles 50, the moisture is attached or adsorbed to the voids 2 and the communication holes and stays in the artificial soil particles 50, and water leaked by gravity (gravity water). Reduced. As a result, the water retention of the artificial soil particles 50 can be improved. In addition, by improving water retention, artificial soil particles can continuously supply water to plants over a long period of time, and the number of watering operations can be greatly reduced.

  Thus, when the external environment becomes wet, the artificial soil particles 50 can absorb and retain external moisture in the artificial soil particles 50, and can ensure water retention required for the soil above a certain level. On the other hand, when the external environment is in a dry state, the moisture retained in the voids 2 of the fiber lump 10 is released to the outside. Thereby, a plant can utilize a water | moisture content easily. As described above, the artificial soil particles 50 achieve excellent water retention by the voids 2 existing between the fibers 1 forming the fiber lump 10.

  Here, the size, number, shape, and the like of the voids 2 formed inside the fiber lump 10 are related to, for example, the amount of water that the artificial soil particles 50 can hold, so-called water retention. The state of the void 2 can be adjusted by changing the amount (density) of the fiber 1 used when granulating the fiber lump 10, the type, thickness, length, and the like of the fiber 1. The size of the fiber 1 is preferably 5 to 100 μm in thickness and preferably 0.3 to 10 mm in length. Moreover, it is preferable to use a flexible fiber so that the fiber 1 can be kept in an intertwined state. Thereby, it can be set as the structure where the space | gap 2 of the artificial soil particle 50 was more dense and complicated.

  The fibers 1 constituting the fiber lump 10 are preferably organic fibers so that sufficient moisture can be retained in the voids 2 in the fiber lump 10. Since the organic fiber is relatively flexible, the fibers 1 constituting the fiber lump 10 can be intertwined in a complex manner to form a large number of voids 2. Thereby, the water retention of the fiber lump 10 is increased, and the water absorbed by the artificial soil particles 50 can be held as water that can be easily used by plants, so-called easy water. As a result, plant growth can be promoted. As the organic fiber, either a natural organic fiber or a synthetic organic fiber can be used. Examples of natural organic fibers include silk, wool, cotton, and cellulose fibers. Examples of synthetic organic fibers include nylon fibers, polyester fibers, vinylon fibers, aramid fibers, rayon fibers, polypropylene fibers, polyethylene fibers, polyurethane fibers, and the like. Among these organic fibers, cellulose fibers are preferably used for natural organic fibers, and vinylon fibers are preferably used for synthetic organic fibers. As the fiber 1, it is possible to use a mixture of natural organic fibers and synthetic organic fibers.

  The fiber length of the fibers 1 constituting the fiber lump 10 is related to the water retention of the artificial soil particles 50. By adjusting the fiber length of the fiber 1, the adsorptive power between the fiber 1 and water can be controlled. The fiber length of the fiber 1 is preferably 0.5 to 2000 μm. When the fiber length is shorter than 0.5 μm, sufficient water retention cannot be obtained. On the other hand, if the fiber length is longer than 2000 μm, the adsorptive power between the water and the fiber becomes too strong, and the easy-to-use water that can be used by the plant decreases.

  As the binder for binding the fibers 1, either an organic binder or an inorganic binder can be used. Organic binders include, for example, polyolefin binders, polyvinyl alcohol binders, polyurethane binders, polyvinyl chloride binders, polyester binders, styrene binders, and synthetic resin binders such as polyvinyl acetate binders, starch, carrageenan, Examples include natural product binders such as xanthan gum, gellan gum, polysaccharides such as alginic acid, and animal proteins such as glue. Examples of the inorganic binder include silicate binders such as water glass, phosphate binders such as aluminum phosphate, borate binders such as aluminum borate, and hydraulic binders such as cement. An organic binder and an inorganic binder can be used in combination of two or more.

  The binder is preferably a water-insoluble binder. Thereby, it can prevent that the structure of the artificial soil particle 50 collapses by irrigation etc. Examples of the water-insoluble binder include a resin material. Examples of such resin materials include polyolefin resins such as polyethylene and polypropylene, vinyl chloride resins such as polyvinyl chloride and polyvinylidene chloride, polyester resins such as polyethylene terephthalate, styrene resins such as polystyrene, acetic acid, and the like. Examples thereof include vinyl and vinyl acetate resins such as ethylene vinyl acetate, polyurethane, and urethane resins such as vinyl urethane. Of these, polyethylene is preferred. Instead of resin materials, polymer gelling agents such as acrylamide, natural polysaccharide gelling agents such as alginate and carrageenan, rubber coating agents such as natural rubber and silicone rubber, etc. can be used. is there. Furthermore, a resin cross-linking agent can also be used. Examples of such resin crosslinking agents include isocyanates, vinyl sulfone compounds, aziridines, dihydrazides, methylated amines, diglycidyl ethers, carbodiimides, formaldehyde, titanium coupling agents, silane coupling agents, and the like.

  The mixing ratio of the fiber 1 and the binder is preferably 55:45 to 95: 5, more preferably 70:30 to 90:10, by weight. When the mixing ratio of the fiber 1 and the binder is smaller than 55:45 (that is, when the binder is excessively mixed with the fiber 1), the void 2 formed between the fibers 1 is blocked by the binder, and the artificial soil There is a possibility that the water retention of the particles 50 may decrease. On the other hand, when the mixing ratio of the fiber 1 and the binder is larger than 95: 5 (that is, when the binder is insufficient with respect to the fiber 1), the binding force between the fibers 1 is insufficient, and the strength of the artificial soil particle 50 is increased. May decrease.

  When granulating the artificial soil particles 50, as shown in FIG. 1, an inorganic filler 3 may be contained. In this case, artificial soil particles having the characteristics of the inorganic filler 3 can be produced by adding the inorganic filler 3 in addition to the fibers and the binder. For example, as shown in FIG. 1B, when the inorganic filler 3 to be added has pores 4, when water is added to the raw material of the artificial soil particles 50 and kneaded, the inorganic filler is added to the surface of the fiber 1. In the state where 3 is adhered, the pores 4 of the inorganic filler 3 absorb moisture, and the kneaded material becomes viscous. As a result, the fibers 1 are easily bundled and the fiber lump 10 can be easily formed. Examples of the inorganic filler 3 include diatomaceous earth, perlite, vermiculite, zeolite, bentonite, clay, and porous glass beads. These inorganic fillers 3 may be used alone or in combination of two or more. A preferred inorganic filler 3 is diatomaceous earth. When granulating the fiber lump 10 serving as the base of the artificial soil particles 50, when diatomaceous earth is added to the fiber 1, the diatomaceous earth absorbs moisture and exhibits viscosity, so that the fibers 1 can be easily bonded to each other.

  When granulating the artificial soil particles 50, a thickener may be further added in addition to the inorganic filler 3. The addition amount of a thickener is 1-30 weight part with respect to the inorganic filler 3 (100 weight part), Preferably it is 3-20 weight part. When the addition amount of the thickener is less than 1 part by weight with respect to the inorganic filler 3 (100 parts by weight), the effect of the thickener may not be sufficiently exhibited. On the other hand, even if the addition amount of the thickener exceeds 30 parts by weight with respect to the inorganic filler 3 (100 parts by weight), the effect does not increase greatly and is not economical.

  The mixing ratio of the fiber 1 and the inorganic filler 3 is preferably 10:90 to 90:10, more preferably 30:70 to 70:30, by weight. When the mixing ratio of the fiber 1 and the inorganic filler 3 is smaller than 10:90 (that is, when the inorganic filler 3 is excessively mixed with the fiber 1), the void 2 formed between the fibers 1 becomes the inorganic filler 3 In other words, the durability and strength of the artificial soil particles 50 may be reduced because the fibers are completely filled with each other and the consolidation of the fibers by the binder is hindered. On the other hand, when the mixing ratio of the fiber 1 and the inorganic filler 3 is larger than 90:10 (that is, the inorganic filler 3 is insufficient with respect to the fiber 1), the properties of the inorganic filler 3 are sufficient in the artificial soil particle 50. There is a risk that it will not be demonstrated.

  The particle size of the artificial soil particles 50 is appropriately selected depending on the plant to be cultivated, but when targeting a houseplant or a flower bud, 1 to 10 mm is preferable, 2 to 8 mm is more preferable, and 2 to 5 mm is even more preferable. When the particle size of the artificial soil particles 50 is less than 1 mm, the size of the gap formed between the artificial soil particles becomes small, and moisture is excessively held by the capillary force of the gap. As a result, it is difficult to absorb oxygen from the roots of the plant due to reduced drainage, and root rot may occur. On the other hand, when the particle size of the artificial soil particle 50 exceeds 10 mm, the size of the gap becomes large and the drainage property becomes excessive, so that the plant becomes difficult to absorb moisture, or the artificial soil becomes sparse and the plant becomes sparse. There is a risk of falling down. The particle size of the artificial soil particles 50 can be adjusted by sieving.

  The particle size of the artificial soil particles 50 is determined by the following measurement method. First, the artificial soil particles 50 to be measured are observed together with a scale with a camera or a microscope, and an image thereof is acquired using image processing software (two-dimensional image analysis processing software “WinROOF”, manufactured by Mitani Corporation). 100 artificial soil particles 50 are selected from the image, and the outline of the artificial soil particles 50 is traced. The diameter of the equivalent circle is calculated from the circumference of the traced figure. The average of the diameters (100) of the equivalent circles obtained from the respective artificial soil particles 50 is defined as the average size (unit: pixel). Then, the average size is compared with the scale in the image, converted to a unit length (μm order to mm order), and the particle size of the artificial soil particles 50 is calculated. Incidentally, the size of the fibers 1 constituting the artificial soil particles 50 is also determined by a measurement method using image processing. The median diameter of the artificial soil particles 50 is calculated from the obtained particle diameter of the artificial soil particles 50.

  As described above, a plurality of voids 2 capable of retaining moisture are formed in the artificial soil particle 50, and the formation state of the voids 2 can be evaluated by the porosity and the pore volume. When used as an artificial soil medium for foliage plants or flowers, the porosity of the artificial soil particles 50 is preferably 60 to 70%, and more preferably 65 to 70%. The pore volume of the artificial soil particles 50 is preferably 0.9 to 1.4 mL / g, and more preferably 1.1 to 1.4 mL / g. When the porosity is smaller than 60% or the pore volume is smaller than 0.9 mL / g, the water that can be held in the artificial soil particles 50 is reduced, and the adsorption force between the artificial soil particles 50 and the water is increased. Over time, the easy-to-use water available to plants decreases. When the porosity is greater than 70%, or when the pore volume is greater than 1.4 mL / g, the artificial soil particles 50 become brittle, and the artificial soil particles 50 cannot sufficiently absorb moisture and become gravity water. Leakage of water increases. The pore volume and porosity of the artificial soil particles 50 can vary depending on the type, composition, and granulation conditions of the filler 2 and the binder. Depending on the state of the object to be measured, the pore volume and porosity can be determined by an optimum 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. Can be measured.

<Method for producing artificial soil particles>
The artificial soil particle 50 according to the present invention is manufactured by performing a kneading step of mixing at least the fiber 1 and a binder, and an extrusion granulation step of extruding and granulating the kneaded material obtained in the kneading step. The In addition, before the kneading process, fibers 1 that have been preliminarily arranged to a predetermined length are prepared. For example, the fibers 1 such as cellulose or vinylon are drawn with a carding device or the like and cut to a length of about 3 to 10 mm.

[Kneading process]
In the kneading step of kneading the raw materials, the fiber 1 cut to an appropriate length and the binder are mixed, and water is added to knead. Thereby, the kneaded material in the state in which the fibers 1 are randomly oriented is obtained. In the kneading step, it is also possible to add the inorganic filler 3 to the fiber 1 and the binder. Thereby, the characteristic of the inorganic filler 3 is added to a kneaded material. When adding the inorganic filler 3, it is possible to add a thickener further. Thereby, the viscosity of the kneaded product can be increased, and the fibers in the kneaded product are easily collected.

[Extrusion granulation process]
FIG. 2 is an explanatory diagram of the extrusion granulation step of the artificial soil particles 50 performed using the extrusion granulator 20. In the extrusion granulation step, granulation is performed while extruding the kneaded product 40 using the extrusion granulator 20 to form artificial soil particles 50. FIG. 2A shows a part of the extrusion granulator 20 as a cross section. FIG. 2B is an enlarged view of a region A2 surrounded by a broken-line circle in the extrusion granulator 20 of FIG. 2A, and schematically illustrates how the kneaded product 40 is cut while being granulated. It is shown. As shown in FIG. 2A, the extrusion granulator 20 mainly includes a case 31, an extrusion screw 32, a screen die 33, and rollers 34 and 35. The case 31 has an internal space, and the extrusion screw 32 is fitted into the internal space. A screen die 33 having a hole 33 a is attached to the front end side of the case 31. The diameter of the hole 33a of the screen die 33 is preferably 1 to 10 mm, and more preferably 1 to 5 mm. When the diameter of the hole 33a of the screen die 33 is less than 1 mm, the particle size of the artificial soil particles 50 to be generated becomes too small. Therefore, when the artificial soil medium is prepared, the artificial soil particles 50 become dense and water retention There is a possibility that air permeability may be reduced. On the other hand, when the diameter of the hole 33a of the screen die 33 exceeds 10 mm, the particle size of the artificial soil particles 50 to be generated becomes too large, so when the artificial soil medium is prepared, the artificial soil particles 50 become sparse and the plant It becomes difficult to stably support As shown in FIG. 2B, the rollers 34 and 35 are provided with cutting teeth 34a and 35a on the outer circumferences of the rollers 34 and 35, respectively. The kneaded product 40 is cut by abutting while being rolled up. The rollers 34 and 35 can be vibrated in a direction parallel to their rotational axes (that is, the front-rear direction of the paper surface of FIG. 2). In this case, the teeth 34a and 35a move while twisting with respect to the rotation axis direction of the roller. For this reason, the cut surface of the kneaded material 40 can be made smooth. The extruding granulator 20 shown in FIG. 2 is an example of a means for carrying out the extruding granulation step, and any other type of extruding granulator can be used as long as it can cut while extruding by applying pressure to the kneaded product. A granulator may be used.

In carrying out the extrusion granulation step, first, the kneaded product 40 is put into the case 31 of the extrusion granulator 20. Next, pressure is applied to the kneaded material 40 in the case 31 by inserting the extrusion screw 32 from the rear part of the case 31 and moving the extrusion screw 32 toward the front end side of the case 31 while rotating. The pressure added to the kneaded material 40 is 5-30 kg / cm < ² >, and 10-20 kg / cm < ² > is preferable. When the pressure applied to the kneaded material 40 is less than 5 kg / cm ² , the fibers are not sufficiently curved and the fibers exist in the artificial soil particles 50 while maintaining the original shape (for example, a straight shape). The water retention rate may be reduced. On the other hand, when the pressure applied to the kneaded material 40 exceeds 30 kg / cm ² , excessive pressure is applied to the fibers, so that the gaps between the fibers are compressed and become small, and the water retention rate may be reduced. When the extrusion granulation step is performed at an appropriate pressure, the randomly oriented fibers in the kneaded product 40 are compressed and shrunk. The shrunken fibers in the kneaded product 40 are in a state of being intertwined in a complicated manner. The kneaded product 40 is pressed against the screen die 33 and is pushed out from a hole 33 a provided in the screen die 33. The extruded kneaded product 40 is granulated while being cut by the teeth 34a, 35a, and artificial soil particles 50 are generated. Here, the cutting speed of the kneaded material 40 by the teeth 34a, 35a is set to a speed that generates 1 to 380 artificial soil particles 50 per second, and preferably 5 to 150 speeds per second. Is set. For example, when the artificial soil particles 50 are granulated from a predetermined amount of the kneaded material 40, if the cutting speed of the kneaded material 40 is less than 1 per second, the particle size of the artificial soil particles 50 becomes too large, so that the artificial soil The size of the gap formed between the particles increases, and as a result, the drainage property becomes excessive, making it difficult for the plant to absorb moisture, or the artificial soil becomes sparse and the plant may fall over. On the other hand, if the kneaded product 40 is cut more than 380 per second, the particle size of the artificial soil particles 50 becomes too small, and the size of the gap formed between the artificial soil particles becomes small. Water is strongly held by force. In this case, easy-to-use water that can be used by the plant is reduced, oxygen is not easily absorbed from the root of the plant, and there is a possibility that withering may occur. The cutting speed of the kneaded material 40, that is, the speed at which the artificial soil particles 50 are generated can be adjusted by changing the diameters and rotation speeds of the rollers 34 and 35, for example.

  After the extrusion granulation step, the artificial soil particles 50 are dried until a predetermined moisture content is obtained. Thereafter, classification is performed as necessary.

  The moisture retention characteristics of the artificial soil particles according to the present invention were evaluated. In this example, the amount of water retained in the artificial soil particles by one irrigation was measured, and the water retention characteristics of the artificial soil particles were evaluated from the obtained measured values.

[Preparation of artificial soil particles]
<Example>
338 g of organic fibers (KC Flock (registered trademark) W-100GK, manufactured by Nippon Paper Industries Co., Ltd.) and 338 g of diatomaceous earth (Radiolite (registered trademark) 1500 H, manufactured by Showa Chemical Industry Co., Ltd.), an inorganic filler, Polyolefin-based resin emulsion (Sumitomo Seika Co., Ltd., Sepoljon (registered trademark) G315, concentration 40% by weight) 311 g as binder, and methylcellulose (Marporose (registered trademark) 90MP, Matsumoto Yushi Seiyaku Co., Ltd.) as a thickener 14 g and 892 g of water were stirred at room temperature for 4 minutes until the respective materials were sufficiently mixed to obtain a kneaded product. Then, the kneaded extruding granulator (high-performance automatic roller type system PT6025, Akira Kiko Co., Ltd.) was charged into an extrusion from the hole of the screen die by adding the pressure 10 kg / cm ² in the kneaded product was extruded The kneaded material was cut by a roller (diameter: 122 mm, rotation speed: 6 to 10 rpm) to generate 7 to 60 artificial soil particles per second. The cut artificial soil particles were heated at 80 ° C. for 16 hours, heated at 120 ° C. for 3 hours and dried, and then cooled to obtain artificial soil particles of Examples.

<Comparative example>
Cellulose fibers, which are organic fibers (KC Flock (registered trademark) W-100GK, manufactured by Nippon Paper Industries Co., Ltd.) 338 g, and diatomaceous earth, which is an inorganic porous material (Radiolite (registered trademark) 1500H, manufactured by Showa Chemical Industry Co., Ltd.) 338 g Are added to a stirring and mixing granulator (manufactured by G-Labo Co., Ltd.), and while stirring and rolling until uniform, granulation liquid (binding material) 1164 g is added and granulated. A granular material impregnated with was formed. The granulation liquid consists of 347 g of a polyolefin resin emulsion (Sumitomo Seika Co., Ltd., Sepoljon (registered trademark) G315, concentration 40% by weight) as a binder, and potassium alginate (made by Wako Pure Chemical Industries, Ltd.) as a thickener. Reagent) 6 g and 811 g of water were mixed, and the mixture was stirred for 1 hour at room temperature until each material was sufficiently mixed. Next, the granular material is heated at 80 ° C. for 16 hours using a dryer, dried by heating at 120 ° C. for 3 hours, and the cellulose fibers and diatomaceous earth are fixed with a binder, and this is cooled and artificial soil particles of a comparative example It was.

[Evaluation of water retention of artificial soil particles]
A stainless cup (diameter 50 mm × height 51 mm, capacity 100 cc) with a plurality of drain holes having a diameter of about 1 mm provided on the bottom surface at an interval of about 2 mm is filled with 100 cc of artificial soil particles to be tested, and 50 cc of water is added from above. The weight at the time when the water was no longer discharged from the bottom of the cup was measured. Subsequently, an additional 50 cc of water was added to the artificial soil particles, and the weight when water was no longer discharged from the bottom of the cup was measured. Repeating this operation, when the weight of the artificial soil particles containing water becomes constant, from the weight of the artificial soil particles at that time, subtract the weight of the artificial soil particles before dripping the water measured in advance, This was defined as the water retention amount of the artificial soil particles. And the water retention of the artificial soil particle was evaluated from this water retention amount.

  Table 1 below shows the evaluation results of water retention of the artificial soil particles of Examples and Comparative Examples.

  The artificial soil particles of the examples had increased pore volume, pore surface area, median diameter, and porosity compared to the artificial soil particles of the comparative example. As a result, the artificial soil particles of the example had a water retention amount of 48 cc per 100 cc of artificial soil particles, and increased by about 20% with respect to the water retention amount of the artificial soil particles of the comparative example (40 cc per 100 cc of artificial soil particles). became. Thus, it was suggested that the artificial soil particles produced by the extrusion granulation method have improved water retention as compared with the conventional artificial soil particles produced by the stirring granulation method. It is considered that the capacity to hold moisture in the artificial soil particles increased with the increase in porosity.

  FIG. 3 is an enlarged view (photograph) of (a) artificial soil particles according to an example and (b) artificial soil particles according to a comparative example. FIG. 4 is a cross-sectional view of (a) artificial soil particles according to an example obtained by X-ray CT analysis, and (b) artificial soil particles according to a comparative example. When (a) and (b) of each figure are compared, the shape of the fiber of the artificial soil particles according to the example was not clearly confirmed. Artificial soil particles produced by the extrusion granulation method are considered to have been granulated in a state where the fibers are compressed and contracted because pressure is applied during granulation. On the other hand, it was confirmed that the artificial soil particles according to the comparative example have fibers substantially linear. In the agitation granulation method, pressure is not applied during granulation, so it is considered that the fibers were granulated while maintaining the original shape.

  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, etc., but is cultivated in a plant factory or the like. It can also be used for the purpose of producing artificial soil particles used as a growth medium for vegetables and the like.

DESCRIPTION OF SYMBOLS 1 Fiber 2 Space | gap 10 Fiber block 33 Screen die 40 Kneaded material 50 Artificial soil particle

Claims (7)

A kneading step of mixing at least fibers and a binder;
An extrusion granulation step of extruding and granulating the kneaded product obtained in the kneading step;
For producing artificial soil particles. In the extrusion granulation step, the kneaded product is extruded from a screen die at a pressure of 5 to 30 kg / cm ² , and the kneaded product extruded from the screen die is cut to obtain 1 to 380 artificial soil particles per second. The manufacturing method of the artificial soil particle of Claim 1 to produce | generate.   3. The method for producing artificial soil particles according to claim 1, wherein in the kneading step, a mixing ratio of the fibers and the binder is 55:45 to 95: 5 by weight ratio.   The method for producing artificial soil particles according to any one of claims 1 to 3, wherein an inorganic filler is further added in the kneading step.   5. The method for producing artificial soil particles according to claim 4, wherein in the kneading step, when the inorganic filler is added, 1 to 30 parts by weight of a thickener is further added to 100 parts by weight of the inorganic filler.   The method for producing artificial soil particles according to claim 4 or 5, wherein a mixing ratio of the fibers and the inorganic filler is 10:90 to 90:10 by weight. Artificial soil particles having a fiber mass formed by collecting fibers,
The fibers constituting the fiber lump are bound by a binder in a state of being entangled and entangled,
The porosity is 60-70%,
Artificial soil particles having a pore volume of 0.9 to 1.4 mL / g.

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