JPWO2015141262A1 - Fertilizer particles and method for producing the same - Google Patents

Abstract

The fertilizer particle | grains which concern on this invention contain the liquid fertilizer containing a fertilizer component, and the shell which includes the said liquid fertilizer. The shell is made of polyester having a molecular structure in which a polycarboxylic acid having a valence of 2 or more and a polyol having a valence of 2 or more are polycondensed.

Description

  The present invention relates to fertilizer particles in which liquid fertilizer is encapsulated and a method for producing the same.

  A fertilizer adjusts the cultivation floors, such as soil, to a state suitable for growing plants such as agricultural crops, and is supplied as nutrients to the plants. Fertilizers play an important role, especially in the agricultural field. Examples of components (fertilizer components) that can be used as fertilizers include compounds including three major elements such as nitrogen, potassium, and phosphorus required by plants, and other essential and useful elements. Moreover, the said fertilizer may contain suitably additives, such as a pH adjuster for adjusting the pH of a cultivation bed. The fertilizer component acts on the cultivated floor or plants by spreading or diffusing the fertilizer on the cultivated floor. In recent years, liquid fertilizers (liquid fertilizers) in which the fertilizer components are blended at a ratio according to the growth conditions of plants have been proposed (see, for example, Patent Documents 1 and 2).

  Liquid fertilizer is excellent in absorbability of fertilizer components to plants. However, since the liquid fertilizer has high diffusibility of the fertilizer component on the cultivation floor, the fertilizer component is hardly retained on the cultivation floor. In addition, plants need to be continuously supplied with nutrients during the growth process. For this purpose, the frequency of fertilizing liquid fertilizer may be increased. On the other hand, a technique capable of continuously supplying fertilizer components to plants without increasing the frequency is desired.

  As one of the techniques described above, particulate fertilizer (fertilizer particles) containing liquid fertilizer has been studied. As the fertilizer particles, liquid fertilizers and fertilizer particles composed of porous particles that hold the fertilizer particles are known (for example, see Patent Document 3). Further, fertilizer particles composed of a liquid fertilizer and a resin shell enclosing it are proposed in some documents (see, for example, Patent Document 4).

JP 2007-145614 A JP 2011-105541 A Japanese Patent Laid-Open No. 06-285358 JP 2003-175092 A

  In general, it is desirable that the fertilizer particles exhibit a fertilizer effect suitable for plant growth for a certain period after fertilization, and thereafter, it is desirable that the fertilizer particles do not remain on the cultivation bed so as not to contaminate the cultivation bed. In the fertilizer particles described in Patent Document 3, since the porous particles are composed of inorganic components, the porous particles may remain on the cultivation bed without being decomposed. In addition, if the liquid fertilizer is simply retained on the porous base material, the moisture in the soil easily enters the particles, so that the liquid fertilizer may quickly flow out of the particles.

  On the other hand, the shell of the fertilizer particle | grains described in patent document 4 is comprised with the biodegradable resin obtained by the polycondensation of hydroxycarboxylic acid, for example. The shell of the biodegradable resin is decomposed while the liquid fertilizer is gradually released, and substantially disappears from the cultivation bed after the completion of the sustained release. On the other hand, the fertilized cultivation floor generally has many microorganisms, and in such a fertile cultivation floor, the sustained release period of the liquid fertilizer by the fertilizer particles is shortened, and the supply of the liquid fertilizer may not be suitable for plant growth. is there. In addition, liquid fertilizer may leak during storage before fertilizer particles are applied. Thus, in patent document 4, the performance calculated | required when actually using the fertilizer particle | grains which enclose a liquid fertilizer is not considered sufficiently.

  This invention makes it a subject to provide the fertilizer particle | grains which express the stable sustained release property of liquid fertilizer irrespective of the microorganisms quantity of a cultivation bed, and are excellent in storage stability.

  The present invention is a fertilizer particle comprising a liquid fertilizer containing a fertilizer component and a shell enclosing the liquid fertilizer, wherein the shell is composed of a polycarboxylic acid having a valence of two or more and a polyol having a valence of two or more. Fertilizer particles composed of polyester having a condensed molecular structure are provided.

  The present invention also includes a step of producing a core-shell type droplet in which a liquid fertilizer droplet containing a fertilizer component is covered with the polyester solution, and the liquid-fertilizer droplet in the core-shell type droplet. Depositing the polyester from a solution of the polyester to be wrapped, and the polyester has a molecular structure in which a polycarboxylic acid having a valence of 2 or more and a polyol having a valence of 2 or more are polycondensed, a method for producing fertilizer particles, I will provide a.

  According to the present invention, the shell enclosing the liquid fertilizer is composed of chemically relatively stable polyester by polycondensation of polycarboxylic acid and polyol. For this reason, the fertilizer particle | grains which express the stable sustained release property irrespective of the amount of microorganisms of a cultivation bed, and are excellent in storage stability are provided.

It is a figure which shows roughly the structure of an example of the double tube dripping apparatus used for manufacture of the fertilizer particle | grains which concern on this embodiment.

  Hereinafter, fertilizer particles according to an embodiment of the present invention will be described. The fertilizer particles according to the present embodiment include a liquid fertilizer and a shell that encloses the liquid fertilizer. The shell is made of polyester having a molecular structure in which a polycarboxylic acid having a valence of 2 or more and a polyol having a valence of 2 or more are polycondensed.

  By spreading fertilizer particles on the cultivation floor, moisture in the cultivation bed penetrates into the shell of the fertilizer particles, so that the shell is plasticized and biodegraded (hydrolyzed) by microorganisms in the cultivation bed. By this plasticization and hydrolysis, the release of the liquid fertilizer contained in the shell is started and accelerated.

  On the other hand, since liquid fertilizer is liquid, it generally tends to penetrate into the shell. If the hydrolysis of the shell is significant, the liquid fertilizer is excessively released to the cultivation floor, and the sustained release period of the liquid fertilizer is shortened and may become insufficient.

  However, the fertilizer particles according to the present embodiment exhibit stable sustained release performance for a long time. Furthermore, the fertilizer particles are excellent in storage stability. This is because the polyester constituting the shell is rich in crystallinity, and as a result, excessive penetration of the liquid fertilizer into the shell is suppressed, and biodegradation of the shell is also appropriately suppressed. Conceivable. For this reason, the fertilizer particles have storage stability and stable sustained release performance even if the fertilized bed is rich in microorganisms.

<Liquid fertilizer>
The liquid fertilizer is a liquid composition containing a fertilizer component. The liquid fertilizer may be comprised only from the fertilizer component, and may be comprised from the fertilizer component and the solvent. For example, the liquid fertilizer may be a solution or suspension in which a solid fertilizer component is dissolved or suspended in the above-mentioned solvent, or a liquid containing an organic component that suitably works for plant growth as the above-mentioned fertilizer component. There may be.

  One or more of the solvents may be used. Examples of the solvent include water and organic solvents such as alcohols, ketones, and esters. The solvent is preferably composed mainly of water. Examples of the above-mentioned solvent containing water as a main component include water and a mixed liquid of water and a water-soluble organic solvent and containing a larger amount of water.

  The fertilizer component is an inorganic or organic component that can effectively act on the growth of plants as a fertilizer. The fertilizer component may be one kind or more. The fertilizer component only needs to contain a desired amount of a desired element. Examples of the elements include N, P, K, Ca, Mg, S, B, Fe, Mn, Cu, Zn, Mo, Essential elements of Cl, O, H and C, and useful elements such as Si and Na are included. Examples of the fertilizer component include a component containing the element and an organic component suitable for plant growth.

  Examples of the components containing the above elements include urea, ammonium nitrate, ammonium nitrate, ammonium chloride, ammonium sulfate, ammonium phosphate, sodium nitrate, calcium nitrate, potassium nitrate, lime nitrogen, formaldehyde processed urea (UF), acetaldehyde processed urea (CDU), isobutyraldehyde processed urea (IBDU), nitrogenous fertilizer components such as guanane urea (GU); superphosphate, heavy superphosphate, molten phosphorus, humic acid phosphorus, calcined phosphorus, heavy calcined phosphorus, Phosphorous fertilizer components such as bituminous superphosphate, ammonium polyphosphate, potassium metaphosphate, calcium metaphosphate, bitter phosphate, ammonium sulfate, potassium phosphate sodium, ammonium phosphate phosphate; potassium chloride, potassium sulfate, potassium sulfate, Potassium sulfate such as potassium sulfate, potassium bicarbonate, potassium phosphate Fertilizer component; Silicate fertilizer component such as calcium silicate; Magnesium fertilizer component such as magnesium sulfate and magnesium chloride; Calcium fertilizer component such as quick lime, slaked lime and calcium carbonate; Manganese sulfate, sulfated manganese manganese, mineral manganese, etc. Manganese fertilizer components; boron fertilizer components such as boric acid and borate; iron-containing fertilizer components such as steel slag.

  Moreover, an anti-stress component is contained in the example of the organic component suitable for the said plant growth. The stress component is extracted from a natural product, for example. Examples of the anti-stress component include saccharides and amino acids.

  Examples of the saccharide include glycerol, erythritol, erythrulose, erythrose, threose, xylose, ribose, arabinose, lyxose, deoxyribose, ribulose, arabitol, fructose, inositol, rhamnose, mannitol, sorbitol, glucose, gluconic acid, mannose, alto Loose, idose, galactose, quinobose, glucaric acid, gulose, digitalose, digitoxose, cimarose, sorbose, tagalose, talose, fucose, psicose, galactitol, iduronic acid, galacturonic acid, glucuronic acid, mannuronic acid, galactosamine, glucosamine, fucosamine, Mannosamine, muramic acid, curdlan, maltitol, trehalose, melibiose, sucrose, lac , Palatinose, agarobiose, isomaltose, xylobiose, gentiobiose, cordiobiose, chondroucine, cellobiose, sophorose, nigerose, hyalurouronic acid, maltose, lactulose, laminaribiose, lutinose, glucosyl sucrose, raffinose, gentianose, tritoose Triose, melendiose, stachyose, xylo-oligosaccharide, isomaltoligosaccharide, gentio-oligosaccharide, fructooligosaccharide, chitosan oligosaccharide, chitin oligosaccharide, cellooligosaccharide, cyclodextrin, pectin, starch, agarose, amylose, amylopectin, arabinan, arabinogalactan, Alginic acid, inulin, galactan, xylan, chitin, chitosan, glycogen, glucoma Nan, keratan sulfate, colominic acid, chondroitin, chondroitin sulfate, cellulose, dextran, hyaluronic acid, pectin, pectic acid, heparan sulfate, heparin, mannan, lichenan, include levan and lentinan.

  Examples of the amino acids include alanine, arginine, asparagine, aspartic acid, cysteine, glutamine, glutamic acid, glycine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, threonine, tryptophan, tyrosine, valine, and Dimers of these amino acids are included. Examples of such dimers include cystine.

  The content of the fertilizer component in the liquid fertilizer can be appropriately determined based on, for example, the desired supply amount of the fertilizer component. For example, if the concentration of the fertilizer component is made higher, it is possible to increase the amount of the fertilizer component released from the fertilizer particles.

  The said liquid fertilizer may further contain other components, such as a pH adjuster, a thickener, and antioxidant, in the range in which the effect of this invention is acquired.

<Shell>
The shell is made of the polyester. The polyester has a molecular structure in which the polycarboxylic acid and the polyol are polycondensed. The polyester may be one kind or more.

  The polycarboxylic acid is a divalent or higher polycarboxylic acid, that is, a compound having two or more carboxyl groups. The polycarboxylic acid contains a divalent or higher-valent organic group bonded to the carboxyl group. One or more polycarboxylic acids may be used.

  The polyol is a divalent or higher polyol, that is, a compound having two or more hydroxyl groups. The polyol also contains a divalent or higher organic group bonded to the hydroxyl group. One or more polyols may be used.

  The divalent or higher organic group is appropriately selected from known divalent or higher organic groups (for example, an alkylene group, etc.) that can form a polycarboxylic acid or a polyol (that is, can form a polyester). The organic group in the polycarboxylic acid may be the same as or different from the organic group in the polyol.

  In the monomer component for obtaining the polyester, the ratio (Mc / Mo) of the number of moles of the polycarboxylic acid (Mc) to the number of moles of the polyol (Mo) is a quantity ratio usually used for constituting the polyester. For example, it is preferably 70/30 to 30/70, more preferably 45/55 to 55/45, and still more preferably 49/51 to 51/49.

  The molar ratio of the divalent carboxylic acid (dicarboxylic acid) in the polycarboxylic acid and the molar ratio of the divalent alcohol (diol) in the polyol are both preferably 50% or more, and 75% or more. It is more preferable that it is 90% or more. Any of the molar ratios may be 100%.

  The said polyester has a structural unit represented by following formula (1), for example.

The formula (1), R ₁ represents a divalent organic group connecting the carboxyl group in the polycarboxylic acid, R ₂ represents a divalent organic group connecting the hydroxyl group in the polyol. R ₁ and R ₂ may be the same or different, and R ₁ may be one kind or more, and R ₂ may be one kind or more. R ₁ and R ₂ can both be selected from known divalent organic groups capable of constituting a polyester by polycondensation of the polycarboxylic acid and the polyol.

For example, R ₁ may be a hydrocarbon group that may contain an aromatic group, or may be a polymer chain. R ₁ may be, for example, a divalent organic group represented by the following formula (2) or formula (3).

  In the above formula (2), A represents a hydrogen atom or a monovalent aromatic hydrocarbon group, m, n, o represent an integer of 0 or more, and m + n is an integer of 1 or more. In the above formula (3), B represents a divalent aromatic hydrocarbon group, and m and n are integers of 0 or more. In the above formula (2) or (3), m + n is preferably 20 or less, and o is preferably 10 or less from the viewpoint of easy handling of the polycarboxylic acid in the synthesis of the polyester.

Examples of R ₁ may specifically include an alkylene group having 2 to 20 carbon atoms and a divalent aromatic group having 6 to 18 carbon atoms, but other divalent organic groups include It may be included.

  Examples of the dicarboxylic acid include succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1,2-propanedicarboxylic acid, 1,9-nonanedicarboxylic acid, 1,10-decane. Dicarboxylic acid, 1,11-undecanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,13-tridecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,16-hexadecanedicarboxylic acid and 1,18-octadecanedicarboxylic acid Aliphatic hydrocarbon dicarboxylic acids such as acids; cycloaliphatic dicarboxylic acids such as cyclohexanedicarboxylic acids; and fumaric acid, maleic acid, citraconic acid, mesaconic acid, 2-pentenic acid, methylene succinic acid, allylmalonic acid, isopropyl Such as reddensuccinic acid and 2,4-hexadienic acid. Aliphatic hydrocarbon dicarboxylic acids containing unsaturated double bonds of: terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, diphenylsulfone dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenoxyethanedicarboxylic acid, diphenyldicarboxylic acid, diphenyl Aromatic dicarboxylic acids such as thioether dicarboxylic acids and diphenyl ketone dicarboxylic acids.

R ₂ may be, for example, a hydrocarbon group that may contain an aromatic group, a bisphenol, a glycol, or a glycol addition of a bisphenol. It may be a product or a polymer chain. R ₂ may be represented by, for example, the above formula (2), or may be a divalent organic group represented by the following formula (4) or formula (5).

  In the above formula (4), E, F and G each independently represent a hydrogen atom or a methyl group, X and Y each represents a divalent aromatic hydrocarbon group, and m is an integer of 0 or more. Represents. In the above formula (5), D independently represents a hydrogen atom or a methyl group, and m represents an integer of 1 or more. In the above formula (4) or (5), m is preferably 40 or less from the viewpoint of ease of handling of the polyol in the synthesis of the polyester.

In the example of R ₂ , an alkylene group having 2 to 20 carbon atoms may specifically be included, but other divalent organic groups may be included.

  Examples of the diol include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,4-hexanediol, 1,6-hexanediol, 1,6-octane Diol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanedi All, 1,14-tetradecanediol, 1,16-hexadecanediol, 1,18-octadecanediol, aliphatic hydrocarbon dialcohols such as propylene glycol and neopentyl glycol; alicyclic carbonizations such as cyclohexanediol and cyclohexanedimethanol Hydrogen dialcohol; bisphenol And alkylene oxide adducts of bisphenol; are included.

  Examples of the bisphenol include bisphenol A, bisphenol AP, bisphenol AF, bisphenol B, bisphenol BP, bisphenol C, bisphenol E, bisphenol F, bisphenol G, bisphenol M, bisphenol S, bisphenol P, bisphenol PH, bisphenol TMC and bisphenol. Z is included. Examples of the alkylene oxide adduct include an ethylene oxide adduct and a propylene oxide adduct.

When both R ₁ and R ₂ are compounds represented by the above formula (2), m + n is preferably 4 or more from the viewpoint of enhancing the crystallinity of the polyester. When the crystallinity of the polyester is increased, the penetration of the liquid fertilizer into the shell is suppressed, the storage stability of the fertilizer particles is further increased, and the sustained release period of the liquid fertilizer in the fertilizer particles may be longer. On the other hand, m + n is preferably 16 or less, and more preferably 14 or less, from the viewpoints of availability of the above polyester raw material and ease of production, and improvement of storage stability and sustained release properties. More preferably, it is 12 or less.

  In addition, the amount of one or both of the polycarboxylic acid and the polyol within the above range of m + n is 30 parts by mass or more with respect to 100 parts by mass of all the monomer components constituting the polyester from the viewpoint of enhancing the crystallinity of the polyester. Preferably, it is 50 parts by mass or more, and more preferably 80 parts by mass or more.

The amount of the polycarboxylic acid in which R ₁ is represented by formula (3) and the amount of the polyol in which R ₂ is represented by formula (4) are both biodegraded by microorganisms in the cultivation bed. From the viewpoint of moderately controlling the speed of the polyester, it is preferably 1 to 50 parts by weight, more preferably 2 to 30 parts by weight, and more preferably 5 to 20 parts by weight with respect to 100 parts by weight of all the monomer components of the polyester. More preferably. By optimizing the biodegradation rate, more stable sustained release performance of fertilizer particles can be obtained regardless of the amount of microorganisms in the cultivation bed.

  The polyester may contain a network structure by crosslinking. When the polyester has the network structure, the molecular structure of the shell becomes denser, and the sustained release period of the liquid fertilizer in the fertilizer particles can be extended. In the network structure, a part of the monomer component for constituting the polyester is a trivalent or higher polycarboxylic acid or a trivalent or higher polyol, preferably a trivalent or higher polycarboxylic acid and a trivalent or higher. This is realized by being both polyols.

  From the viewpoint of advantages due to the network structure, the amount of the trivalent or higher polycarboxylic acid in the polycarboxylic acid, or the amount of the trivalent or higher polyol in the polyol is preferably 1 to 60 mol%, More preferably, it is 10-50 mol%, and it is further more preferable that it is 40-50 mol%.

  The network structure can also be realized when one or both of the polycarboxylic acid and the polyol contains a compound containing an unsaturated bond between carbon atoms. The proportion of the compound containing the unsaturated bond in the polycarboxylic acid or the polyol is preferably 1 to 40 mol%, more preferably 5 to 25 mol%, from the viewpoint of the advantage of the network structure. Preferably, it is 10-20 mol%, and it is still more preferable.

  The network structure can be realized by bonding unsaturated bond portions of the compound containing the unsaturated bond directly by radical addition polymerization. Alternatively, the network structure can be realized by bonding unsaturated bond portions of a compound containing the unsaturated bond to each other through another compound having a functional group that bonds to the unsaturated bond. .

  Examples of the trivalent or higher polycarboxylic acids include 1,2,3-propanetricarboxylic acid, cyclohexane-1,2,4-tricarboxylic acid-1,2-anhydride, trimellitic acid and pyromellitic acid. It is. Examples of the trivalent or higher polyol include glycerin, trimethylolethane, trimethylolpropane, pentaerythritol and dipentaerythritol.

  Examples of the polycarboxylic acid containing an unsaturated bond between carbon atoms include the aliphatic hydrocarbon dicarboxylic acid containing an unsaturated double bond described above. Examples of polyols containing an unsaturated bond between carbon atoms include unsaturated diols described in JP2013-035759A.

  The type and amount of the monomer component constituting the polyester, and the presence or absence of the network structure, for example, from the result of analyzing the shell by pyrolysis GC-MS, the measurement result of the insoluble content of tetrahydrofuran (THF) in the polyester, etc. Can be estimated.

  The weight average molecular weight of the polyester is preferably 5,000 to 200,000, and more preferably 10,000 to 150,000, from the viewpoint of securing the strength of the shell and the ease of producing fertilizer particles. If the weight average molecular weight is too small, the strength of the shell may be insufficient, and if the weight average molecular weight is too large, handling of the polyester during the production of fertilizer particles may be more difficult.

  The weight average molecular weight of the polyester can be measured by gel permeation chromatography (GPC). The molecular weight measurement by GPC can be performed by using GPC / HLC-8120 manufactured by Tosoh Corp. as a measuring device, a column / TSKgel SuperHM-M (15 cm) manufactured by Tosoh Corp. as a column, and using THF as a solvent. it can. The said weight average molecular weight is computed from said measurement result using the molecular weight calibration curve created with the monodisperse polystyrene standard sample.

  The acid value of the polyester suppresses the occurrence of an initial burst of fertilizer particles (release 5% of fertilizer components in less than 0.5 days from when sprayed on the cultivation floor) in terms of constructing an appropriate shell. From the viewpoint of achieving the above, it is preferably 1.0 to 20.0 mgKOH / g, and more preferably 1.0 to 15.0 mgKOH / g. If the acid value is too small, the desired capsule-shaped shell may be difficult to obtain, and if the acid value is too large, the effect of suppressing the initial burst may not be sufficiently obtained.

The acid value of the polyester can be measured by the following method. First, the polyester is dissolved in N, N-dimethylformamide to prepare an approximately 1% solution. The solution is then potentiometrically titrated with an N / 10 KOH aqueous solution. And acid value Av is calculated | required from the result of the said titration using following Formula. In the following formula, A represents the amount (mL) required for the titration of the N / 10 KOH aqueous solution, f represents the titer of the N / 10 KOH aqueous solution, and S represents the amount of the polyester subjected to the titration (g). It is.
Acid value Av (mg KOH / g) = (A × f × 5.61) / S

  Although the said shell may be comprised only from the said polyester, in the range from which the effect of this invention is acquired, other components other than the said polyester may further be included. Examples of such other components include bactericides, antibacterial agents, pesticides, colorants, and components (eg, surfactants) to assist in the production of fertilizer particles. In addition, from the viewpoint of adjusting biodegradability, the shell is made of a resin having a lower biodegradability than the polyester or a resin having a higher biodegradability than the polyester, and the appropriate biodegradability by the polyester is impaired. In the range which is not, you may contain further.

<Preferred properties of fertilizer particles>
The volume-based average particle diameter (volume average particle diameter) of the fertilizer particles is preferably 0.1 to 5000 μm. Since the fertilizer particle | grains which have the volume average particle diameter of this range can respond to the cultivation of various plants, it can be used for cultivation of various plants.

  Further, the coefficient of variation CV of the fertilizer particles is preferably 1 to 24% from the viewpoint of further reducing the variation in sustained release attributed to the variation in the particle size of the fertilizer particles.

  The volume average particle size and variation coefficient CV of the fertilizer particles can be measured by a laser diffraction type particle size distribution measuring device, for example, Microtrac MT3300EX (manufactured by Nikkiso Co., Ltd.). Specifically, 10 mg of fertilizer particles are added to 10 mL of a 0.1% by mass aqueous solution of sodium dodecylbenzenesulfonate, and the fertilizer particles are dispersed in the aqueous solution with an ultrasonic disperser for 2 minutes. It is put into a wet cell block of a measuring apparatus, and a volume-based particle size distribution is obtained in a measuring range of 0.04 to 1000 μm. D50 (median diameter) in the particle size distribution is defined as the volume average particle size of the fertilizer particles, and the coefficient of variation CV is obtained from the particle size distribution.

  Moreover, it is preferable that the average thickness of the shell of the said fertilizer particle | grains is 0.005-1250 micrometers from a viewpoint of implement | achieving moderate sustained release property which can respond to the growth of various plants of a liquid fertilizer.

  The average thickness of the shell is measured as follows. That is, the fertilizer particles are fixed in a thermosetting epoxy resin, the epoxy resin lump is cut with a microtome to expose the cross section of the fertilizer particles, and the fertilizer particles with the exposed cross section are randomly extracted at five points. The average value of the thicknesses of the shells of the five fertilizer particles is obtained. Let the average value obtained be the average thickness of the shell.

  Further, when the volume average particle diameter of the fertilizer particles is X and the average thickness of the shell is Y, the ratio Y / X of the average thickness Y to the volume average particle diameter X is 0.05 to 0.25. It is preferable that it is 0.08-0.25, and it is further more preferable that it is 0.10-0.23. The ratio Y / X being within the above-mentioned range means that the shell for enclosing a sufficient amount of liquid fertilizer for growing plants is constructed, and the liquid fertilizer included in the shell leaks. It is preferable from the viewpoint of storage without fertilization, and from the viewpoint of expressing more stable sustained release, in which the fertilizer particles are not affected by the amount of microorganisms in the cultivation bed.

<Manufacturing method of fertilizer particles>
The fertilizer particles include a step of preparing a core-shell type droplet in which a liquid fertilizer droplet containing a fertilizer component is covered with the polyester solution, and the liquid fertilizer droplet in the core-shell type droplet. And a step of precipitating the polyester from the solution of the polyester to be wrapped. The manufacturing method can be performed by using a method of forming a film of the polyester solution around the liquid fertilizer droplets.

The core-shell type droplets are composed of a (W ₁ phase) / (O phase) emulsion composed of a first aqueous phase (W ₁ phase) that is a liquid fertilizer and an oil phase (O phase) that is a solution of the polyester. W ₁ / O emulsion), and then the W ₁ / O emulsion is emulsified with the second aqueous phase (W ₂ phase) (W ₁ phase) / (O phase) / (W ₂ phase) emulsion It can be produced by producing (W ₁ / O / W ₂ emulsion). The W ₁ / O emulsion can be produced, for example, by supplying the W ₁ phase to the stirred O phase at an appropriate rate.

  Alternatively, the core-shell type liquid droplets are supplied to the second aqueous phase that is being stirred at the same time from the inner tube and the oil phase from the outer tube using a double tube dropping device ( It can also be produced by dripping).

  The composition of the second aqueous phase usually does not contain a fertilizer component, unlike the composition of the first aqueous phase. However, the second aqueous phase may be the same as the first aqueous phase.

The precipitation of the polyester from the core-shell type droplets can be performed by distilling off the solvent contained in the O phase from the system in which the core-shell type droplets are dispersed. The solvent can be distilled off by one or both of pressure reduction and heating in the dispersion system. By precipitating the polyester in the droplets of the core-shell type, cover the surface of the droplets of the W ₁ phase, the polyester film-like shell is formed.

  The O phase is composed of the polyester and a solvent capable of dissolving the polyester and dispersing and emulsifying the liquid fertilizer. Examples of the solvent include known halogenated hydrocarbons, ketones, ethers, esters, and aromatic hydrocarbons. Examples of the halogenated hydrocarbon include dichloromethane, chloroform, chloroethane, dichloroethane, trichloroethane and carbon tetrachloride. Examples of the ketones include acetone, methyl ethyl ketone and methyl isobutyl ketone. Examples of the ethers include tetrahydrofuran, ethyl ether and isopropyl ether. Examples of the esters include ethyl acetate and butyl acetate. Examples of the aromatic hydrocarbon include benzene, toluene and xylene.

The W ₁ phase contains the liquid manure. For example, the W ₁ phase may be the liquid fertilizer itself or a solution of the liquid fertilizer.

The O phase or the W ₁ phase may further contain a surfactant in order to stably form and maintain a W ₁ / O emulsion. Examples of the surfactant include polyoxyethylene alkyl ether, alkylamine salt, alkylbetaine, alkylamine oxide, quaternary ammonium salt, polyoxyalkylene derivative, sorbitan fatty acid ester, sorbitol fatty acid ester, polyoxyethylene sorbitan fatty acid Ester, polyoxyethylene sorbitol fatty acid ester, glycerin fatty acid ester, polyoxyethylene fatty acid ester, polyoxyethylene alkylamine, alkyl alkanolamide, alkyl sulfate ester salt, polyoxyethylene hydrogenated castor oil, polyoxyethylene alkyl ether sulfate ester salt, Alkyl benzene sulfonates, other sulfonates, fatty acid salts, and other polymeric surfactants are included.

The surfactant may be contained in either the O phase or the W ₁ phase, but is preferably contained in the O phase from the viewpoint of stably forming the W ₁ / O emulsion.

  The polyester may be a commercially available product or a synthetic product. Examples of catalysts used in the synthesis of the polyester include alkali metal compounds such as sodium and lithium; alkaline earth metal compounds such as magnesium and calcium; zinc, manganese, antimony, titanium, tin, zirconium, germanium, etc. Phosphorous compounds; phosphoric acid compounds; amine compounds; sulfur-containing acids such as sulfuric acid, alkyl sulfuric acid, alkylbenzene sulfonic acid and alkoxybenzene sulfonic acid.

  When the polyester includes an unsaturated bond for forming the network structure, a further component may be added to the O phase for the purpose of bonding the unsaturated bonds in the synthesis of the polyester. . Examples of such additional components include polymerization initiators and chain transfer agents. The polymerization initiator and the chain transfer agent may each be one kind or more.

  Examples of the polymerization initiator include persulfates such as potassium persulfate, sodium persulfate, and ammonium persulfate; redox initiators that combine the persulfate and a reducing agent such as acidic sodium sulfite; hydrogen peroxide, 4 , 4'-azobiscyanovaleric acid, t-butyl hydroperoxide, cumene hydroperoxide, and other water-soluble polymerization initiators; redox initiators in which the water-soluble polymerization initiator is combined with a reducing agent such as ferrous salt Benzoyl peroxide; and 2,2'-azobisisobutyronitrile.

  Examples of the chain transfer agent include t-dodecyl mercaptan, n-octyl mercaptan, 2-mercaptoethanol and diisopropyl xanthogen.

  The polyester in the O phase may further contain a crosslinking group. The bridging group is a functional group that reacts and bonds to each other, and may be one kind or more. In the case where the polyester includes the crosslinking group, the polyester including the network structure described above can be obtained by further including a step of bonding the crosslinking groups in the solution of the polyester in the core-shell type droplet. It becomes possible.

  The reaction for bonding the cross-linking groups can be appropriately determined according to the type of the cross-linking group. For example, the reaction may be a polycondensation reaction for synthesizing the polyester or other reaction. Good. Examples of the crosslinking group include a carboxyl group, a hydroxyl group, an amino group, a glycidyl group, and an unsaturated bond between carbon atoms such as a double bond between carbon atoms.

  In the polyester, the cross-linking groups may be arranged uniformly or may be arranged in an uneven manner. If the amount of the crosslinking group in the polyester is too small, the effect of the network structure may not be sufficiently obtained, and if it is too large, the sustained release period may be too long. From such a viewpoint, the amount of the crosslinking group is preferably 0.1 to 20 mol%, more preferably 0.5 to 15 mol%, based on all monomer components constituting the polyester. Preferably, it is 1.0 to 10 mol%.

  In the case where the crosslinking group is a group bonded by a polycondensation reaction, a polyester having the network structure is obtained by a polyester synthesis reaction. In the case where the crosslinking group is a group bonded by a reaction other than the polycondensation reaction, the polyester having the network structure is obtained by performing the reaction after the polyester synthesis reaction.

  For example, when the bridging group is the intercarbon unsaturated bond, the polymerization initiator or chain transfer agent is further added to the O phase containing the polyester containing the unsaturated bond, and the core-shell type It is possible to bond the unsaturated bonds to each other by radical addition polymerization reaction in a liquid forming a droplet and forming a shell of the core-shell type droplet.

  It is preferable that the fertilizer particles have the network structure in the shell from the viewpoints of controlling the sustained release properties of the fertilizer particles, improving the storage stability, and suppressing biodegradability.

  The particles forming the shell as described above are taken out from the liquid phase by a usual method such as filtration. The extracted particles can be dried by a usual method as necessary. Thus, the fertilizer particles are obtained.

For example, the fertilizer particles may be added to the W ₁ / O emulsion by gradually adding a poor solvent for the polyester to reduce the solubility of the polyester in the O phase to the surface of the droplets of the W ₁ phase. It can also be produced by precipitating the polyester.

  The fertilizer particles can be granulated by bonding the fertilizer particles with a known excipient or thickener. Examples of the excipient include sugars, cellulose derivatives, amino acids, proteins, polyacrylic acid derivatives, organic salt inorganic salts, and water-soluble polymers that do not dissolve the polyester. The excipient may be a single type or a mixture of a plurality of types at an appropriate ratio higher than that.

  Examples of the sugar include D-mannitol, sodium alginate, fructose, dextran, dextrin, sucrose, D-sorbitol, lactose, glucose, maltose, starches and trehalose.

  Examples of the cellulose derivative include carboxymethylcellulose, hydroxypropylmethylcellulose, ethylcellulose, hydroxymethylcellulose, hydroxypropylcellulose, cellulose acetate phthalate, hydroxypropylmethylcellulose phthalate and hydroxymethylcellulose acetate succinate.

  Examples of the amino acids include glycine, alanine, tyrosine, arginine and lysine.

  Examples of such proteins include gelatin, fibrin, collagen and albumin.

  Examples of the polyacrylic acid derivative include sodium polyacrylate and a methacrylic acid / acrylic acid copolymer (Eudragit, manufactured by Laem Co.). "Eudragit" is a registered trademark of the company.

  Examples of the organic salt include sodium citrate, sodium tartrate, sodium carbonate and potassium carbonate.

  Examples of the inorganic salt include sodium chloride, potassium chloride, sodium phosphate and potassium phosphate.

  Examples of the water-soluble polymer that does not dissolve the polyester include polyvinyl pyrrolidone and polyvinyl alcohol.

<Effect>
As is clear from the above description, the fertilizer particles include a liquid fertilizer containing a fertilizer component, and a shell containing the liquid fertilizer, and the shell includes a divalent or higher polycarboxylic acid and a divalent or higher value. It is comprised by the polyester which has the molecular structure which polycondensed with the polyol of. For this reason, the said fertilizer particle | grains express the stable sustained release property irrespective of the amount of microorganisms of a cultivation bed, and are excellent in storage stability.

  Moreover, it is much more effective that the said polyester contains network structure in the molecular structure from the viewpoint of control of the said sustained release, improvement of storage stability, and suppression of biodegradability.

  Moreover, it is much more effective from a viewpoint utilized for the cultivation of various plants that the volume average particle diameter of the said fertilizer particle | grain is 0.1-5000 micrometers.

  The ratio Y / X of the average thickness Y of the shell to the volume average particle size X of the fertilizer particles is 0.05 to 0.25, from the viewpoint of accommodating a sufficient amount of liquid fertilizer in the fertilizer particles, fertilizer It is more effective from the viewpoint of suppressing the leakage of liquid fertilizer during storage of particles and the viewpoint of stabilizing the sustained release, and Y / X is 0.10 to 0.23. Is even more effective.

  Further, the method for producing the fertilizer particles includes a step of producing a core-shell type droplet in which a liquid fertilizer droplet containing the fertilizer component is covered with the polyester solution, and the liquid in the core-shell type droplet. And the step of precipitating the polyester from the polyester solution that wraps the fertilizer droplets, so that the fertilizer particles exhibit stable sustained release regardless of the amount of microorganisms in the cultivation bed and have excellent storage stability. Can be provided.

  Further, the polyester includes a cross-linking group, and the manufacturing method further includes a step of bonding the cross-linking groups in the solution of the polyester in the core-shell type droplets to control the sustained release of fertilizer particles. From the viewpoints of improving the storage stability and suppressing biodegradability.

  The fertilizer particles are sprayed on a cultivation floor such as soil where plants are grown. Since the particle fertilizer has good storage stability, it is easily and well dispersed on the cultivation floor. In addition, since the fertilizer particles have moderate biodegradability and good sustained release properties, the fertilizer components are supplied to the plant in the expected amounts over time regardless of the amount of microorganisms (fertility) in the cultivation floor. can do. The liquid fertilizer in the fertilizer particles is gradually released to the outside of the fertilizer particles by, for example, swelling of the shell (the polyester) due to moisture in the cultivation bed or decomposition of the polyester by microorganisms in the cultivation bed. The

[Preparation of polyester]
<Synthesis of polyester resin 1>
After charging the following compound group 1 into a three-necked flask, 0.5 parts by mass of tetrabutoxy titanate was added as a catalyst. Thereafter, the inside of the container is depressurized, the air in the container is replaced with nitrogen gas to make an inert atmosphere, the mixed liquid in the container is heated to 230 ° C. while stirring, and the generated water is distilled off. The reaction was allowed for 5 hours. Then, it air-cooled, the pressure reduction in a container was cancelled | released, reaction was stopped, and polyester resin 1 (PE1) was obtained. It was 23500 when the weight average molecular weight (Mw) of PE1 was measured by GPC. Moreover, it was 7 mgKOH / g when the acid value (Av) of PE1 was measured by titration. “PEG-600” means “polyethylene glycol (Mw: 600)”.
(Compound group 1)
Succinic acid (SCA) 30 parts by mass 1,2-propanedicarboxylic acid (12PDCA) 33 parts by mass Ethylene glycol (EG) 15 parts by mass Propylene glycol (PG) 18 parts by mass PEG-600 4 parts by mass

<Synthesis of polyester resin 2>
In the synthesis of PE1, a polyester resin 2 (PE2) was obtained in the same manner as the synthesis of PE1, except that the compound group 1 was changed to the following compound group 2. The Mw of PE2 was 22000, and the Av of PE2 was 8 mgKOH / g.
(Compound group 2)
Succinic acid 10 parts by weight Glutaric acid (GA) 50 parts by weight Ethylene glycol 15 parts by weight Propylene glycol 15 parts by weight PEG-600 10 parts by weight

<Synthesis of polyester resin 3>
In the synthesis of PE1, polyester resin 3 (PE3) was obtained in the same manner as the synthesis of PE1, except that the compound group 1 was changed to the following compound group 3. The Mw of PE3 was 23400, and the Av of PE3 was 3 mgKOH / g. “BPA-PO (3)” means “propylene oxide 3 mol adduct of bisphenol A”.
(Compound group 3)
Succinic acid 25 parts by mass 1,2-propanedicarboxylic acid 32 parts by mass Ethylene glycol 25 parts by mass BPA-PO (3) 18 parts by mass

<Synthesis of polyester resin 4>
In the synthesis of PE1, a polyester resin 4 (PE4) was obtained in the same manner as the synthesis of PE1, except that the compound group 1 was changed to the following compound group 4. The amount of 123PTCA in the polycarboxylic acid is 42.4 mol%, and the amount of GL in the polyol is 44.0 mol%. The Mw of PE4 was 20700, and the Av of PE4 was 2 mgKOH / g.
(Compound group 4)
Succinic acid 30 parts by weight 1,2,3-propanetricarboxylic acid (123PTCA) 33 parts by weight Ethylene glycol 15 parts by weight Glycerin (GL) 18 parts by weight PEG-600 4 parts by weight

<Synthesis of polyester resin 5>
In the synthesis of PE1, the polyester resin 5 (PE5) was obtained in the same manner as the synthesis of PE1, except that the compound group 1 was changed to the following compound group 5 and the heating time at 230 ° C. was shortened to 2 hours. It was. The Mw of PE5 was 5200, and the Av of PE5 was 6 mgKOH / g.
(Compound group 5)
Adipic acid (AA) 55 parts by mass 1,4-hexanediol (14HDO) 30 parts by mass BPA-PO (3) 10 parts by mass PEG-600 5 parts by mass

<Synthesis of polyester resin 6>
In the synthesis of PE5, polyester resin 6 (PE6) was obtained in the same manner as the synthesis of PE5 except that the heating time at 230 ° C. was shortened to 3 hours. The Mw of PE6 was 10100, and the Av of PE6 was 5 mgKOH / g.

<Synthesis of polyester resin 7>
In the synthesis of PE5, polyester resin 7 (PE7) was obtained in the same manner as the synthesis of PE5 except that the heating time at 230 ° C. was changed to 5 hours. The Mw of PE7 was 20900, and the Av of PE7 was 6 mgKOH / g.

<Synthesis of polyester resin 8>
In the synthesis of PE5, polyester resin 8 (PE8) was obtained in the same manner as the synthesis of PE5 except that the catalyst was changed to 0.25 parts by mass of dibutyltin oxide and the heating time at 230 ° C. was changed to 8 hours. . The Mw of PE8 was 147900, and the Av of PE8 was 3 mgKOH / g.

<Synthesis of polyester resin 9>
In the synthesis of PE1, a polyester resin 9 (PE9) was obtained in the same manner as the synthesis of PE1, except that the compound group 1 was changed to the following compound group 9. The Mw of PE9 was 20100, and the Av of PE9 was 7 mgKOH / g.
(Compound group 9)
Suberic acid (SBA) 55 parts by mass 1,6-octanediol (16 ODO) 35 parts by mass PEG-600 10 parts by mass

<Synthesis of polyester resin 10>
In the synthesis of PE1, a polyester resin 10 (PE10) was obtained in the same manner as the synthesis of PE1, except that the compound group 1 was changed to the following compound group 10. The Mw of PE10 was 23700, and the Av of PE10 was 3 mgKOH / g.
(Compound group 10)
Suberic acid 50 parts by weight Naphthalenedicarboxylic acid (NDCA) 5 parts by weight 1,6-octanediol 35 parts by weight BPA-PO (3) 10 parts by weight

<Synthesis of polyester resin 11>
In the synthesis of PE1, a polyester resin 11 (PE11) was obtained in the same manner as the synthesis of PE1, except that the compound group 1 was changed to the following compound group 11. The Mw of PE11 was 22400, and the Av of PE11 was 4 mgKOH / g.
(Compound group 11)
Sebacic acid (SEA) 48 parts by weight Phthalic acid (PHA) 5 parts by weight 1,8-octanediol (18 ODO) 35 parts by weight BPA-PO (3) 12 parts by weight

<Synthesis of polyester resin 12>
After charging the following compound group 12 into a three-necked flask, 0.5 parts by mass of tetrabutoxy titanate was added as a catalyst. Thereafter, the inside of the container is depressurized, the air in the container is replaced with nitrogen gas to make an inert atmosphere, the mixed liquid in the container is heated to 230 ° C. while stirring, and the generated water is distilled off. The reaction was allowed for 5 hours. To the obtained reaction solution, 6 parts by mass of trimellitic acid was added to adjust the acid value, and the mixture was further reacted for 2 hours. Air cooling was performed to release the reduced pressure in the container to stop the reaction, and polyester resin 12 (PE12) was obtained. The Mw of PE12 was 24500, and the Av of PE12 was 19 mgKOH / g.
(Compound group 12)
Sebacic acid 45 parts by weight Phthalic acid (PHA) 5 parts by weight 1,8-octanediol (18 ODO) 32 parts by weight BPA-PO (3) 12 parts by weight

<Synthesis of polyester resin 13>
In the synthesis of PE12, polyester resin 13 (PE13) was obtained in the same manner as PE12 except that the compound group 12 was changed to the following compound group 13 and the addition amount of trimellitic acid was changed to 8 parts by mass. The Mw of PE13 was 23800, and the Av of PE13 was 21 mgKOH / g.
(Compound group 13)
Sebacic acid 45 parts by weight Phthalic acid 5 parts by weight 1,8-octanediol 30 parts by weight BPA-PO (3) 12 parts by weight

<Synthesis of polyester resin 14>
In the synthesis of PE1, a polyester resin 14 (PE14) was obtained in the same manner as the synthesis of PE1, except that the compound group 1 was changed to the following compound group 14. The Mw of PE14 was 21800, and the Av of PE14 was 7 mgKOH / g.
(Compound group 14)
1,14-tetradecanedicarboxylic acid (114TDCA) 45 parts by weight Phthalic acid 6 parts by weight 1,12-dodecanediol (112DDO) 37 parts by weight BPA-PO (3) 12 parts by weight

<Synthesis of polyester resin 15>
In the synthesis of PE1, a polyester resin 15 (PE15) was obtained in the same manner as the synthesis of PE1, except that the compound group 1 was changed to the following compound group 15. The amount of fumaric acid (FA) in all monomer components is 14.8 mol%. The Mw of PE15 was 8200, and the Av of PE15 was 4 mgKOH / g.
(Compound group 15)
1,14-tetradecanedicarboxylic acid 35 parts by weight Fumaric acid (FA) 8 parts by weight Phthalic acid 5 parts by weight 1,12-dodecanediol 42 parts by weight BPA-PO (3) 10 parts by weight

<Synthesis of polyester resin 16>
In the synthesis of PE1, a polyester resin 16 (PE16) was obtained in the same manner as the synthesis of PE1, except that the compound group 1 was changed to the following compound group 16. The Mw of PE16 was 22500, and the Av of PE16 was 3 mgKOH / g.
(Compound group 16)
1,16-hexadecanedicarboxylic acid (116HDCA) 43 parts by weight Phthalic acid 7 parts by weight 1,14-tetradecanediol (114 TDO) 40 parts by weight BPA-PO (3) 10 parts by weight

<Synthesis of polyester resin 17>
As will be described later, polyester resin 17 (PE17) was obtained by crosslinking polyester resin PE15 during the fertilizer particle production process.

<Synthesis of polyester resin 18>
In the synthesis of PE1, a polyester resin 18 (PE18) was obtained in the same manner as the synthesis of PE1, except that the compound group 1 was changed to the following compound group 18. The Mw of PE18 was 21800, and the Av of PE18 was 2 mgKOH / g.
(Compound group 18)
46 parts by mass of hydroxycarboxylic acid (3H4PBA) of the following formula (6) 46 parts by mass of 3-hydroxypropionic acid (3HPA) 8 parts by mass of PEG-600

<Synthesis of polyester resin 19>
In the synthesis of PE1, a polyester resin 19 (PE19) was obtained in the same manner as the synthesis of PE1, except that the compound group 1 was changed to the following compound group 19. The Mw of PE19 was 20300, and the Av of PE19 was 3 mgKOH / g.
(Compound Group 19)
Pantoic acid (PAA) 5 parts by mass γ-hydroxybutyric acid (GHB) 55 parts by mass Vanillic acid (VA) 40 parts by mass

<Synthesis of polyester resin 20>
In the synthesis of PE1, a polyester resin 20 (PE20) was obtained in the same manner as the synthesis of PE1, except that the compound group 1 was changed to the following compound group 20. The Mw of PE20 was 23500, and the Av of PE20 was 5 mgKOH / g.
(Compound group 20)
12-hydroxystearic acid (12HSA) 50 parts by mass 3-hydroxypropionic acid 20 parts by mass Vanillic acid 30 parts by mass

  Tables 1 to 3 show the materials PE1, PE20, Mw, Av, and the presence or absence of a network structure. In the table, “the network structure” is “present” means that the crosslinking group introduced into the polyester molecule is reacted, and “the network structure” is “not” means that the crosslinking group is reacted. Means not.

[Production of fertilizer particles 1]
<Preparation of O phase>
10 parts by mass of PE1 solid was added to 90 parts by mass of ethyl acetate, and the resulting mixture was stirred at 900 rpm for 30 minutes using a homogenizer to obtain an ethyl acetate solution of PE1. In this solution, 2 parts by mass of polyoxyethylene lauryl ether (Emalgen 106, manufactured by Kao Corporation, “Emalgen” is a registered trademark of the company) as HLB10.5 was dissolved to obtain an oil phase (O phase).

<Preparation of W ₁ phase>
As a fertilizer component, 2 parts by mass of potassium sulfate, 2 parts by mass of ammonium sulfate, and 1 part by mass of phosphoric acid were added to 95 parts by mass of water, and the obtained mixed solution was stirred at 900 rpm for 30 minutes using a homogenizer. to give a first aqueous phase _{(W 1} phase). W _1-phase is a liquid fertilizer.

<Production of _W 1 / O emulsion>
100 parts by mass of the O phase was put into a container, and 100 parts by mass of the W ₁ phase was dropped into the O phase at a dropping rate of 20 g / min while stirring the O phase with a homogenizer set at 1200 rpm. The turbid liquid was further stirred for 30 minutes with a stirrer set at a rotation speed of 500 pm to obtain a W ₁ / O emulsion which was a water-in-oil emulsion.

<Production of _W 1 / O / _{W 2} emulsion>
In a separate container, 500 parts by mass of pure water and 5 parts by mass of polyoxyethylene lauryl ether (Emalgen 102KG, manufactured by Kao Corporation) having an HLB of 6.3 are charged, and the resulting mixture is rotated at 500 pm. The mixture was stirred for 10 minutes with the set stirrer to obtain a _second aqueous phase (W2 phase). Stirring blade S type set to 300 rpm; with stirring (made of SUS304 AS ONE Corporation) in _{W 2} phase was added dropwise to _{W 2} phases the _W 1 / O emulsion 100 parts by weight at a rate of 10 g / min, dropwise Thereafter, stirring was further continued for 30 minutes to obtain a W ₁ / O / W ₂ emulsion that was a water-in-oil-in-water emulsion.

<Production of fertilizer particles>
W ₁ / O / _{W 2} dispersoids in the emulsion while reducing the pressure _W 1 / O / _{W 2} emulsion under reduced degrees of the (water-in-oil droplets) does not occur rupture (in 5 Pa) continued stirring for 24 hours Then, ethyl acetate contained in the O phase was distilled off to obtain a dispersion in which W / O type microcapsules were dispersed. The obtained dispersion was filtered, and the obtained filtrate was dried by air drying at 25 ° C. for 60 hours to obtain fertilizer particles 1 consisting of the PE1 shell and the liquid fertilizer contained therein. The volume-based average particle size (volume average particle size) X of the fertilizer particles 1 is 62 μm, the coefficient of variation CV in the volume-based particle size distribution is 21%, the average thickness Y is 8.2 μm, The ratio Y / X of the average thickness to the volume average particle diameter was 0.13.

  The volume average particle size X and the coefficient of variation CV are, as described above, the D50 and the coefficient of variation of the volume-based particle size distribution obtained using the laser diffraction particle size distribution measuring device (Microtrack MT3300EX (Nikkiso Co., Ltd.)). It is. The average thickness Y is the average value of the thickness of the shell in the cross section of the five fertilizer particles confined in the epoxy resin, as described above.

[Fabrication of fertilizer particles 2-8, 21-26, 28-30]
Fertilizer particles were obtained in the same manner as fertilizer particles 1 except that PE2-8, PE11-16, and PE18-20 were used instead of PE1. The fertilizer particles produced using PE2-8 are respectively fertilizer particles 2-8, the fertilizer particles produced using PE11-16 are respectively fertilizer particles 21-26, and the fertilizer particles produced using PE18-20 are respectively used. Fertilizer particles 28-30.

  X of the fertilizer particle 2 was 59 μm, CV was 19%, Y was 7.9 μm, and Y / X was 0.13. X of the fertilizer particle 3 was 56 μm, CV was 21%, Y was 7.8 μm, and Y / X was 0.14. X of the fertilizer particle 4 was 64 μm, CV was 24%, Y was 9.1 μm, and Y / X was 0.14. X of the fertilizer particle 5 was 60 μm, CV was 19%, Y was 8.3 μm, and Y / X was 0.14. X of the fertilizer particle 6 was 62 μm, CV was 18%, Y was 8.6 μm, and Y / X was 0.14. X of the fertilizer particle 7 was 66 μm, CV was 18%, Y was 9.2 μm, and Y / X was 0.14. X of the fertilizer particle 8 was 61 μm, CV was 19%, Y was 7.9 μm, and Y / X was 0.13.

  X of the fertilizer particle 21 was 64 μm, CV was 21%, Y was 9.7 μm, and Y / X was 0.15. X of the fertilizer particle 22 was 67 μm, CV was 20%, Y was 9.1 μm, and Y / X was 0.14. X of the fertilizer particle 23 was 68 μm, CV was 19%, Y was 9.5 μm, and Y / X was 0.14. X of the fertilizer particle 24 was 58 μm, CV was 22%, Y was 8.9 μm, and Y / X was 0.15. X of the fertilizer particle 25 was 59 μm, CV was 27%, Y was 9.4 μm, and Y / X was 0.16. X of the fertilizer particle 26 was 64 μm, CV was 25%, Y was 9.4 μm, and Y / X was 0.15.

  X of the fertilizer particle 28 was 63 μm, CV was 18%, Y was 10.2 μm, and Y / X was 0.16. X of the fertilizer particles 29 was 59 μm, CV was 21%, Y was 9.1 μm, and Y / X was 0.15. X of the fertilizer particle 30 was 68 μm, CV was 21%, Y was 11.3 μm, and Y / X was 0.17.

[Production of fertilizer particles 9]
<Preparation of O phase and W ₁ phase>
By adding 14.0 parts by mass of PE9 solids to 126.0 parts by mass of ethyl acetate and stirring the resulting mixture at 900 rpm for 30 minutes using a homogenizer, an ethyl acetate solution (phase O) of PE9 was obtained. Obtained. It was also prepared the same first aqueous phase and W ₁ phase of the fertilizer particles 1 (W ₁ phase).

<Production of _W 1 / O emulsion>
40 parts by mass of the O phase was put into a container, 1.1 parts by mass of Emulgen 106 (manufactured by Kao Corporation) was added to the O phase, and the prepared W ₁ was stirred with a homogenizer set at 800 rpm. 160 parts by mass of the phase was added dropwise to the O phase at a dropping rate of 20 g / min, and the mixture was further stirred for 30 minutes with a stirrer whose rotational speed was set to 500 rpm to obtain a W ₁ / O emulsion that was a water-in-oil emulsion.

<Production of _W 1 / O / _{W 2} emulsion>
In a separate container, 500 parts by mass of pure water and 5 parts by mass of Emulgen 102KG (manufactured by Kao Corporation) were added, and the resulting mixture was stirred for 10 minutes with a stirrer set at a rotational speed of 500 pm. An aqueous phase (W ₂ phase) was obtained.

<Production of fertilizer particles>
Fertilizer particles were obtained in the same manner as the fertilizer particles 1 except that the W ₁ / O emulsion and W ₂ phase obtained in this production example were used. The obtained fertilizer particles are designated as fertilizer particles 9. X of the fertilizer particle 9 was 63 μm, CV was 19%, Y was 2.4 μm, and Y / X was 0.04.

[Production of fertilizer particles 10]
In the preparation of the W ₁ / O emulsion, the amount of the O phase was changed to 55 parts by mass, the added amount of Emulgen 106 was changed to 1.4 parts by mass, the dripping amount of the W ₁ phase was changed to 145 parts by mass, and the stirring speed of the stirrer was changed to 600 rpm. Except for the above, fertilizer particles were obtained in the same manner as the fertilizer particles 9. The obtained fertilizer particles are designated as fertilizer particles 10. X of the fertilizer particle 10 was 61 μm, CV was 17%, Y was 2.9 μm, and Y / X was 0.05.

[Production of fertilizer particles 11]
In the preparation of the W ₁ / O emulsion, the amount of the O phase was changed to 75 parts by mass, the added amount of Emulgen 106 was changed to 1.7 parts by mass, the dripping amount of the W ₁ phase was changed to 125 parts by mass, and the stirring speed of the stirrer was changed to 600 rpm. Except for the above, fertilizer particles were obtained in the same manner as the fertilizer particles 9. The obtained fertilizer particles are defined as fertilizer particles 11. X of the fertilizer particle 11 was 61 μm, CV was 21%, Y was 5.6 μm, and Y / X was 0.09.

[Fabrication of fertilizer particles 12]
In the preparation of the W ₁ / O emulsion, the amount of the O phase was changed to 80 parts by mass, the added amount of Emulgen 106 was changed to 1.8 parts by mass, the dripping amount of the W ₁ phase was changed to 120 parts by mass, and the stirring speed of the stirrer was changed to 700 rpm. Except for the above, fertilizer particles were obtained in the same manner as the fertilizer particles 9. The obtained fertilizer particles are defined as fertilizer particles 12. X of the fertilizer particle | grains 12 was 67 micrometers, CV was 21%, Y was 7.2 micrometers, and Y / X was 0.11.

[Production of fertilizer particles 13]
In the preparation of the W ₁ / O emulsion, the amount of the O phase was changed to 125 parts by mass, the added amount of Emulgen 106 was changed to 1.9 parts by mass, the dripping amount of the W ₁ phase was changed to 75 parts by mass, and the stirring speed of the stirrer was changed to 800 rpm. Except for the above, fertilizer particles were obtained in the same manner as the fertilizer particles 9. The obtained fertilizer particles are designated as fertilizer particles 13. X of the fertilizer particle 13 was 71 μm, CV was 22%, Y was 15.8 μm, and Y / X was 0.22.

[Production of fertilizer particles 14]
In the preparation of the W ₁ / O emulsion, the amount of the O phase was changed to 135 parts by mass, the added amount of Emulgen 106 was changed to 1.8 parts by mass, the dripping amount of the W ₁ phase was changed to 65 parts by mass, and the stirring speed of the stirrer was changed to 800 rpm. Except for the above, fertilizer particles were obtained in the same manner as the fertilizer particles 9. The obtained fertilizer particles are defined as fertilizer particles 14. X of the fertilizer particle 14 was 65 μm, CV was 22%, Y was 15.9 μm, and Y / X was 0.24.

[Production of fertilizer particles 15]
In the preparation of the W ₁ / O emulsion, the amount of the O phase was changed to 140 parts by mass, the added amount of Emulgen 106 was changed to 1.7 parts by mass, the dripping amount of the W ₁ phase was changed to 60 parts by mass, and the stirring speed of the stirrer was changed to 800 rpm. Except for the above, fertilizer particles were obtained in the same manner as the fertilizer particles 9. The obtained fertilizer particles are designated as fertilizer particles 15. X of the fertilizer particle 15 was 69 μm, CV was 21%, Y was 17.7 μm, and Y / X was 0.26.

[Fabrication of fertilizer particles 16]
<Preparation of O phase and W ₁ phase>
An oil phase (O phase) was obtained in the same manner as the O phase of the fertilizer particle 1 except that PE10 was used instead of PE1. It was also prepared the same first aqueous phase and W ₁ phase of the fertilizer particles 1 (W ₁ phase).

<Production of _W 1 / O emulsion>
100 parts by mass of the O phase of this production example was put into a container, and 100 parts by mass of the W ₁ phase was added dropwise to the O phase at a dropping rate of 1.0 g / min while stirring the O phase with a homogenizer set at 1500 rpm. Subsequently, the mixture was further stirred for 30 minutes with a stirrer whose rotation speed was set to 500 pm to obtain a W ₁ / O emulsion which was a water-in-oil emulsion.

<Production of _W 1 / O / _{W 2} emulsion>
A second water phase (W ₂ phase) identical to the W ₂ phase of the fertilizer particles 1 was prepared in another container. While stirring the W ₂ phase with a stirrer set to 500 rpm, 100 parts by mass of the W ₁ / O emulsion of this production example was added dropwise to the W ₂ phase at a rate of 0.5 g / min. Stirring was continued to obtain a W ₁ / O / W ₂ emulsion which was a water-in-oil-in-water emulsion.

<Production of fertilizer particles>
Stirring is continued for 24 hours while reducing the pressure (at 5 Pa) so that the W ₁ / O / W ₂ emulsion does not rupture, and the ethyl acetate contained in the O phase is distilled off. A dispersion in which microcapsules are dispersed was obtained. The obtained dispersion was filtered off with a filter cloth, and the obtained filtrate was dried by air drying at 25 ° C. for 60 hours to obtain fertilizer particles enclosing the liquid fertilizer. The obtained fertilizer particles are designated as fertilizer particles 16. X of the fertilizer particle 16 was 0.2 μm, CV was 14%, Y was 0.04 μm, and Y / X was 0.20.

[Fabrication of fertilizer particles 17]
The stirring speed of the homogenizer when dropping the W ₁ phase is 1100 rpm, the dropping speed of the W ₁ phase is 10 g / min, and the dropping speed of the W ₁ / O emulsion when preparing the W ₁ / O / W ₂ emulsion is 5 g / min, respectively. Fertilizer particles were obtained in the same manner as the fertilizer particles 16 except that the change was made. The obtained fertilizer particles are designated as fertilizer particles 17. X of the fertilizer particle 17 was 10 μm, CV was 15%, Y was 1.6 μm, and Y / X was 0.16.

[Fabrication of fertilizer particles 18]
The stirring speed of the homogenizer at the time of dropping the W ₁ phase is 800 rpm, the dropping speed of the W ₁ phase is 20 g / min, and the dropping speed of the W ₁ / O emulsion at the time of preparing the W ₁ / O / W ₂ emulsion is 10 g / min, respectively. Fertilizer particles were obtained in the same manner as the fertilizer particles 16 except that the change was made. The obtained fertilizer particles are defined as fertilizer particles 18. X of the fertilizer particles 18 was 58 μm, CV was 21%, Y was 11.2 μm, and Y / X was 0.19.

[Production of fertilizer particles 19]
<Preparation of O phase, W ₁ phase and W ₂ phase>
The same oil phase (O phase) as the W ₁ phase of the fertilizer particles 16, a _first aqueous phase (W ₁ phase), and a second aqueous phase (W ₂ phase) were prepared.

<Production of _W 1 / O / _{W 2} emulsion>
As shown in FIG. 1, the W ₁ phase is placed on the outer pipe of the double pipe dropping device (the inner pipe diameter (ri): 0.5 mm, the outer pipe diameter (ro): 1.0 mm). A tube was charged with the O phase. On the other hand, the _{W 2} phase being stirred at a stirring rate of 400 rpm, from the double-tube dropping device, a _{W 1} phase and O phase, either simultaneously added dropwise at a dropping rate of 0.5 g / min, W _{A 1} / O / W ₂ emulsion was obtained.

  In addition, the said double tube dripping apparatus has the outer tube 1 and the inner tube 2 arrange | positioned inside the outer tube 1, as FIG. 1 shows. The outer tube 1 and the inner tube 2 constitute a double tube structure. The opening of the inner tube 2 is inside the opening of the outer tube 1 and slightly protrudes from the opening of the outer tube 1. The outer tube 1 and the inner tube 2 are connected to cylinders 3 and 4 for quantitatively flowing liquid into the respective tubes.

<Production of fertilizer particles>
Stirring is continued for 24 hours while reducing the pressure (at 5 Pa) so that the W ₁ / O / W ₂ emulsion does not rupture, and the ethyl acetate contained in the O phase is distilled off. A dispersion in which microcapsules are dispersed was obtained. The obtained dispersion was filtered off with a filter cloth, and the obtained filtrate was dried by air drying at 25 ° C. for 60 hours to obtain fertilizer particles enclosing the liquid fertilizer. The obtained fertilizer particles are designated as fertilizer particles 19. X of the fertilizer particle 19 was 580 μm, CV was 22%, Y was 108.2 μm, and Y / X was 0.19.

[Fabrication of fertilizer particles 20]
In place of the double pipe dropping device, a double pipe dropping device having an inner tube diameter of 2.0 mm and an outer tube diameter of 3.5 mm is used, and both the dropping speeds of the W ₁ phase and the O phase are set. Fertilizer particles were obtained in the same manner as the fertilizer particles 19 except that the amount was changed to 30 g / min. The obtained fertilizer particles are designated as fertilizer particles 20. X of the fertilizer particle 20 was 4960 μm, CV was 23%, Y was 841.7 μm, and Y / X was 0.17.

[Production of fertilizer particles 27]
<Production from the O phase to _W 1 / O / _{W 2} emulsion>
A W ₁ / O / W ₂ emulsion was obtained in the same manner as the preparation of the fertilizer particles 25 except that 0.2 parts by mass of 2,2′-azobisisobutyronitrile was added to the O phase as a polymerization initiator. . The W ₁ / O / W ₂ emulsion was heated to 70 ° C. and reacted for 3 hours, and the double bond in PE15 was bonded by an addition reaction. Let PE15 after bridge | crosslinking be the polyester resin 17 (PE17). The Mw of PE17 was 19800, and the Av of PE17 was 4 mgKOH / g.

<Production of fertilizer particles>
Stirring is continued for 24 hours while reducing the pressure (at 5 Pa) so that the W ₁ / O / W ₂ emulsion does not rupture, and the tetrachlorethylene contained in the O phase is distilled off. A dispersion in which capsules were dispersed was obtained. Next, the pressure reduction was stopped while stirring was continued, the inside of the container was purged with nitrogen gas, and 8 parts by mass of a 20% by mass aqueous solution of potassium persulfate was added to the dispersion. Thereafter, the dispersion was heated to 40 ° C. and stirred for 10 hours. Thereafter, the dispersion was filtered off with a filter cloth, and the obtained residue was dried by air drying at 25 ° C. for 60 hours to obtain fertilizer particles enclosing the liquid fertilizer. The obtained fertilizer particles are referred to as fertilizer particles 27. X of the fertilizer particle | grains 27 was 68 micrometers, CV was 19, Y was 9.2 micrometers, and Y / X was 0.14.

  Table 4 shows the types of polyester resins in the fertilizer particles 1 to 30, the volume average particle diameter X of the fertilizer particles, the coefficient of variation CV of the particle diameter distribution, the average thickness Y, and the ratio Y / X of the Y to the X. Show.

[Evaluation]
<Storage stability>
Fertilizer particles 1 to 30 were each put into a glass petri dish and allowed to stand for 60 days in an environment of 30 ° C. and 80% RH. The following evaluation was implemented after leaving still.

(1) Adhering fertilizer particles to the container due to leakage of liquid fertilizer After standing, tilt the glass petri dish to remove the fertilizer particles from the glass petri dish, and determine the adherence of fertilizer particles from the state of the inner surface of the glass petri dish as follows It was evaluated with. If "A" and "B", there is no practical problem.
(Evaluation criteria)
A: No adhesion of fertilizer particles is observed at all on the glass petri dish. Liquid fertilizer has not leaked.
B: Fertilizer particles are adhered to the glass petri dish, but can be removed by lightly rubbing. Liquid fertilizer plasticizes the shell but does not leak.
C: Fertilizer particles are attached to the glass petri dish and cannot be removed by rubbing. Liquid fertilizer is leaking.

(2) Fluidity 10 g of fertilizer particles after standing are placed on a 48 mesh (mesh opening 350 μm) sieve and set on a powder tester (manufactured by Hosokawa Micron Co., Ltd.). After adjusting and applying vibration for 10 seconds, the mass of fertilizer particles remaining on the sieve was measured. And the ratio (residual rate) of the fertilizer particle | grains which remained on the sieve from the following formula was computed, and the fluidity | liquidity of the fertilizer particle | grains was evaluated on the following references | standards from the computed residual rate. The residual rate reflects the frequency of occurrence of fertilizer particle aggregation due to storage. If “AA”, “A” and “B”, there is no practical problem.
(formula)
Residual rate (%) = [{mass of remaining fertilizer particles (g)} / 10 (g)] × 100
(Evaluation criteria)
AA: The residual rate is 0%. Excellent fluidity.
A: The residual ratio is greater than 0% and not more than 3%.
B: The residual ratio is greater than 3% and 20% or less.
C: Residual rate is greater than 20%. Insufficient fluidity.

(3) Discoloration The discoloration of the fertilizer particles after standing was evaluated according to the following criteria. The discoloration is caused by the liquid fertilizer penetrating into the resin film enclosing it and denaturing the resin. If "A" and "B", there is no practical problem.
(Evaluation criteria)
A: There is no discoloration compared to before standing. Fertilizer particles that were pale yellow remain pale yellow.
B: Discolored slightly compared to before standing. The light yellow fertilizer particles have turned yellow.
C: Discolored more intensely than before standing. The light yellow fertilizer particles have turned brown or black.

<Slow release>
The sustained release property of the fertilizer particles was measured and evaluated by the following method.

  First, 10 g of each of the fertilizer particles 1 to 30 is ground in a mortar, mixed with 200 mL of distilled water, sufficiently stirred, and then the fertilizer components in 10 g of each fertilizer particle are determined by quantifying the fertilizer components in the aqueous phase. The initial content of is determined in advance.

Next, 10 g of fertilizer particles and 200 mL of distilled water adjusted to 25 ° C. in advance were put into a container to prepare a sample A for a release test. The elution amount of fertilizer components in the release test sample A is measured every day by quantifying the fertilizer components in the aqueous phase, and 5% of the total fertilizer components contained in the fertilizer particles in the release test sample A are released. The number of days D _{A5 used} and the number of days D _A80 released by 80% were determined from the above measurement results.

Further, 10 g of fertilizer particles, 200 mL of distilled water adjusted to 25 ° C. in advance, and 0.5 g of lipase, which is a degrading enzyme, were put into a container to prepare a release test sample B. The elution amount of the inclusion in the release test sample B is measured every 12 hours (0.5 days) by quantifying the fertilizer components in the aqueous phase, and the total amount of fertilizer particles contained in the release test sample B The number of days _DB80 released by 80% of the fertilizer component was determined from the above measurement results.

Furthermore, the fluctuation ratio of the 80% release date (D _B80 ) of the release test sample B to the 80% release date (D _A80 ) of the release test sample A was obtained from the following formula and evaluated according to the following criteria. If “AA”, “A”, and “B”, there is no practical problem.
(formula)
Fluctuation ratio R _AB (%) = {(D _A80 −D _B80 ) / D _A80 } × 100
(Evaluation criteria)
AA: The fluctuation ratio R _AB is within 5%.
A: The fluctuation ratio R _AB is more than 5% and 10% or less.
B: Fluctuation dynamic ratio R _AB is more than 10% and 20% or less.
C: The fluctuation ratio R _AB exceeds 20%.

<Development evaluation>
Soil A and soil B having different amounts of microorganisms were prepared in a medium of 50 cm in length, 50 cm in width, and 50 cm in depth. When the amount of microorganisms in soil A and soil B was measured by the soil fertility index SOFIX, the amount of microorganisms in soil A was 2.0 × 10 ⁹ (cells / g), and the amount of microorganisms in soil B was 8.0 × 10 ⁹ (cells / g). “SOFIX” is a registered trademark of Ritsumeikan School Corporation.

Each of these soils A and B was mixed with 10 g of fertilizer particles, and then seeded with Komatsuna seeds. The temperature of the cultivation environment was about 23 to 26 ° C., 50 mL of water was sprayed every day, and the growth state of Komatsuna after 15 days was observed. In Soil A and soil B, grown up leaf Komatsuna size were measured, and the size L _B of the largest leaf of Komatsuna maximum leaf size L _A and soil B of Japanese mustard spinach soils A The ratio of the size difference D _AB was determined from the following formula and evaluated according to the following criteria. If “AA”, “A”, and “B”, there is no practical problem.
(formula)
Difference D _AB (%) = {(L _A −L _B ) / L _A } × 100
(Evaluation criteria)
AA: The difference D _AB is within 5%.
A: The difference D _AB is more than 5% and less than 10%.
B: Difference D _AB is more than 10% and less than 20%.
C: The difference D _AB exceeds 20%.

<Biodegradability>
Plants were grown using each fertilizer particle, the soil after harvesting was sieved, the shell of the remaining fertilizer particles was collected, the state was visually observed, and evaluated according to the following criteria. If “A”, there is no practical problem.
(Evaluation criteria)
A: Many holes are present in the shell, and biodegradation is progressing.
B: There are no holes in the shell, and biodegradation has not progressed.

  The evaluation results are shown in Table 5.

  As is apparent from Table 5, the fertilizer particles 1 to 27 have performance that causes no practical problems in any of storage stability, sustained release, growth evaluation, and biodegradability.

  For example, when comparing the fertilizer particles 1 and 2, the fertilizer particles 2 have better performance in terms of storage stability adhesion and sustained release than the fertilizer particles 1. It is effective from the viewpoint of obtaining highly stable fertilizer particles that the hydrocarbon chain that actually connects two carboxyl groups or two hydroxyl groups in the monomer component of the polyester constituting the shell is longer. I understand.

  In addition, for example, the fertilizer particles 3 have better performance than either of the fertilizer particles 1 and 2, as is apparent from the two carboxyl groups or the two hydroxyl groups in the monomer component. It can be seen that the presence of an aromatic group in the organic group connecting each other is more effective from the viewpoint of obtaining fertilizer particles with higher stability.

  Further, for example, the fertilizer particles 11 have better performance than any of the fertilizer particles 1 to 3, as is clear from the organic group that connects two carboxyl groups in the monomer component. It can be seen that the presence of an aromatic group in both of the organic groups connecting two hydroxyl groups is more effective from the viewpoint of obtaining fertilizer particles with higher stability.

  Further, for example, it is clear from the fact that the fertilizer particles 7, 21 and 24 all have the same performance, and have better performance than any of the fertilizer particles 3 and 26. Thus, the above-mentioned monomer component contains 50 masses of a compound in which two carboxyl groups and two hydroxyl groups are connected by a linear hydrocarbon group having 4 to 14 carbon atoms with respect to 100 mass parts of the total monomer components. It can be seen that containing more than one part is more effective from the viewpoint of obtaining fertilizer particles with higher stability.

  Further, for example, all of the fertilizer particles 6 to 8 have the same performance and constitute a shell as is clear from the fact that the fertilizer particles 5 have better performance than the fertilizer particles 5. It is found that the weight average molecular weight of the polyester is 5,000 to 200,000 is effective from the viewpoint of obtaining practical and good fertilizer particles, and the weight average molecular weight is 10,000 to 150,000 from the above viewpoint. It turns out that it is much more effective.

  Further, for example, the fertilizer particles 21 and 22 both have equivalent performance, and as shown by the fact that they have better performance than the fertilizer particles 23, constitute a shell. It turns out that it is effective from a viewpoint of obtaining the fertilizer particle | grains which are practical and favorable as the acid value of polyester is 1-20 mgKOH / g.

  Further, for example, the fertilizer particles 10 have a better performance than the fertilizer particles 9, and the fertilizer particles 14 have a better performance than the fertilizer particles 15. Furthermore, when the ratio Y / X of the average thickness Y of the shell to the volume average particle diameter X of the fertilizer particles is 0.05 to 0.25, it is effective from the viewpoint of obtaining practical and good fertilizer particles. I understand. Furthermore, as the fertilizer particles 11-14 all have better performance than the fertilizer particles 10, the Y / X is 0.08 to 0.25. Furthermore, it turns out that it is much more effective from a viewpoint which obtains practical and favorable fertilizer particle | grains as it is 0.10-0.23.

  Moreover, for example, as the fertilizer particles 16 to 20 all have good and equivalent performance, it is clear that the volume average particle size of the fertilizer particles is in the range of 0.1 to 5000 μm. It turns out that it is effective from a viewpoint of obtaining the fertilizer particle | grains which are practical and have favorable performance.

  Further, for example, the fertilizer particles 4 are much better than the fertilizer particles 1 in any of storage stability, sustained release properties and growth evaluation. This is considered to be because PE4 in the fertilizer particles 4 has a network structure by polycondensation with a tricarboxylic or higher polycarboxylic acid and a trivalent or higher polyol. That is, it turns out that it is effective from a viewpoint of obtaining the fertilizer particle | grains which are practical and have favorable performance that a shell has a network structure.

Further, for example, the fertilizer particles 25 have the same performance as the fertilizer particles 4 except that they are slightly lower in sustained release and growth evaluation, but the fertilizer particles 27 are preserved compared to the fertilizer particles 25. It is much better in terms of fluidity, sustained release and growth evaluation in stability, and even better in fluidity than the fertilizer particles 4. This is considered because PE17 in the fertilizer particle 27 includes an unsaturated double bond between carbon atoms and has a crosslinked structure (network structure) due to the bond of these unsaturated double bonds. In particular, in the fertilizer particle 27, the above-described network structure is formed in a core-shell type droplet (W ₁ / O / W ₂ emulsion), and therefore, the coefficient of variation CV is smaller than that of the fertilizer particle 25. For this reason, it is thought that the above outstanding performance is shown. That is, it turns out that it is much more effective from a viewpoint of obtaining the fertilizer particle | grains which are practical and have favorable performance that a shell has the network structure by the addition bond of an unsaturated bond.

  On the other hand, all of the fertilizer particles 28 to 30 had practically unsatisfactory performance except for biodegradability. This is because the polyester constituting the shell is formed by polycondensation of hydroxyl carboxylic acid. In the polyester, even if the monomer component contains an aromatic group, the shell containing the liquid fertilizer is chemically This is thought to be due to insufficient stability.

  This application claims the priority based on Japanese Patent Application No. 2014-055125 of an application on March 18, 2014. The contents described in the application specification and the drawings are all incorporated herein.

  According to the present invention, liquid fertilizers containing various organic and inorganic components can be stably trapped in the particles, and the liquid fertilizers are not affected by the amount of microorganisms on the cultivation floor when using the fertilizers. Stable and sustained release at a speed. Therefore, the fertilizer component can be easily and more stably supplied to the plant regardless of whether the cultivation floor is fertile. Therefore, according to the present invention, realization and spread of more efficient plant cultivation is expected.

1 Outer tube 2 Inner tube 3, 4 Cylinder

Claims (7)

  A liquid fertilizer containing a fertilizer component; and a shell enclosing the liquid fertilizer, wherein the shell is composed of a polyester having a molecular structure in which a polycarboxylic acid having a valence of 2 or more and a polyol having a valence of 2 or more are polycondensed. Being fertilizer particles.   The fertilizer particle according to claim 1, wherein the polyester includes a network structure in its molecular structure.   The fertilizer particle of Claim 1 or 2 whose volume average particle diameter of the said fertilizer particle is 0.1-5000 micrometers.   The fertilizer particle according to any one of claims 1 to 3, wherein a ratio Y / X of the average thickness Y of the shell to the volume average particle size X of the fertilizer particle is 0.05 to 0.25.   The fertilizer particle according to claim 4, wherein the ratio Y / X is 0.10 to 0.23. Producing a core-shell type droplet in which a liquid fertilizer droplet containing a fertilizer component is covered with a polyester solution;
Depositing the polyester from the polyester solution that wraps the liquid fertilizer droplets in the core-shell droplets,
The polyester has a molecular structure in which a divalent or higher polycarboxylic acid and a divalent or higher polyol are polycondensed.
A method for producing fertilizer particles. The polyester includes a crosslinking group,
The manufacturing method further includes a step of bonding the cross-linking groups in a solution of the polyester in the core-shell type droplets.
The manufacturing method of the fertilizer particle | grains of Claim 6.

Images