JP2002029875A - Slow-release fertilizer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a slow-release fertilizer having fertilizer components coated with coating layers which withstand physical damage and do not remain in the environment after fertilizer application. SOLUTION: This fertilizer contains at least either one of a biodegradable polymer component containing an aliphatic polyester segment of which >=60% of alkyl in a 2-hydroxy-2-alkyl acetic acid unit is methyl and a degradation accelerator for accelerating the degradation of the aliphatic polyester in a fertilizer application state, and an organic fertilizer or inorganic fertilizer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for releasing fertilizer components into surrounding soil or water at an optional concentration according to the purpose and for an arbitrary period.
The present invention relates to a slow-release fertilizer that does not leave substances that exert a load on the environment in soil.

[0002]

2. Description of the Related Art Various fertilizers are used until crops are harvested. However, those that lose their efficacy in a short period of time require many fertilizations and are inefficient in terms of workability and the like. for that reason,
By using a slow-release fertilizer, the number of applications can be reduced, and various slow-release fertilizers have been proposed to date.

[0003] In order to achieve sustained release over a long period of time, it is effective, for example, to coat a fertilizer component with a coating made of a synthetic resin and microencapsulate it. Such granular fertilizers have been devised in various ways. ing.

[0004] However, such granular fertilizers sometimes leave the coating agent in the soil after fertilization. When the coating agent made of a synthetic resin remains in the natural environment, it causes soil pollution and water pollution.

[0005] Therefore, fertilizers using a biodegradable polymer having a predetermined molecular weight as a coating agent have been proposed.
Japanese Unexamined Patent Publication (Kokai) No. 061884) and polycaprolactone (Japanese Patent Laid-Open No. 10-101501).

[0006] However, it has been difficult to obtain sufficient film strength even if the coating agent is composed of a biodegradable polymer such as polylactic acid alone. For this reason, there is a problem in that a physical shock is applied during production and transportation, and cracks and the like are generated in the coating, and the fertilizer component flows out to the outside world before fertilization.

For this reason, a sustained-release fertilizer comprising the above-mentioned biodegradable polymer and a hardly decomposable resin such as a low molecular weight polyolefin and a low molecular weight wax has been proposed (JP-A-9-263476). , After fertilization,
There is a problem that the hardly decomposable resin remains in soil or water.

In order to solve such a problem, an olefin resin having an unsaturated bond is blended with a biodegradable polyester or the like together with an oxidative decomposition promoting substance to form a blend coating agent, and the fertilizer component is coated with the blend coating agent. Sustained-release fertilizers have been proposed (JP-A-9-194280, JP-A-9-309784). The problem that the resin component remains in the soil or the like was solved by decomposing the olefin resin in the soil or the like by the oxidative decomposition accelerating substance composed of a transition metal or the like.

However, the sustained-release fertilizer in which the fertilizer component is coated with the above-mentioned blend coating agent has a problem in that it is difficult to control the thickness of the blend coating agent. For example, when a sustained release fertilizer with a small film thickness is manufactured,
A controlled release fertilizer that is vulnerable to physical impact will be formed.

[0010] Therefore, it has been proposed to form the coating agent with a biodegradable polymer such as polylactic acid having a relatively high molecular weight. By using a high molecular weight biodegradable polymer, it was possible to obtain a slow-release fertilizer having sufficient film strength against physical impact. For this reason, even if a physical shock is received during production and transportation, cracks and the like do not occur in the coating.

[0011]

However, in the case where the coating is composed of a biodegradable polymer such as polylactic acid having a relatively high molecular weight, the rate of hydrolysis of the biodegradable polymer during fertilization is low. The microbial decomposition rate becomes extremely slow, making it difficult to perform stable release for a long period of time. The inventor has solved the above-mentioned problem.

[0012]

According to the present invention, there is provided a slow-release fertilizer according to the present invention, wherein at least 60 mol% of alkyl in the 2-hydroxy-2-alkylacetic acid unit is methyl. Polyester and a biodegradable polymer component containing a decomposition accelerator that promotes the decomposition of the aliphatic polyester in a fertilized state, and a fertilizer component containing at least one of an organic fertilizer and an inorganic fertilizer. Is a slow-release fertilizer.

[0013] In the slow-release fertilizer according to the present invention, the decomposition accelerator may be a transition metal, a transition metal oxide, or a transition metal halide. And a slow-release fertilizer that is a decomposition accelerator containing at least one of an inorganic acid transition metal salt and an organic acid transition metal salt.

Further, the slow-release fertilizer according to the present invention, as described in claim 3, is an invention according to claim 1 or 2, wherein the L-form and the D-form in the 2-hydroxy-2-alkylacetic acid unit are used. Is a slow-release fertilizer having a molar ratio of 1: 3 to 1: 6.

The slow-release fertilizer according to the present invention, as described in claim 4, is the invention according to any one of claims 1 to 3, wherein the aliphatic polyester has a reduced viscosity of 0.1.
It is a slow-release fertilizer that is 15 to 1.0 dl / g.

The slow-release fertilizer according to the present invention, as described in claim 5, is characterized in that, in the invention according to any one of claims 1 to 4, the fertilizer component is replaced with the biodegradable polymer component. It is a slow-release fertilizer coated with a coating material.

The present inventors have developed an aliphatic polyester in which at least 60 mol% of the alkyl in the 2-hydroxy-2-alkylacetic acid unit is methyl, and a decomposition accelerator which promotes the decomposition of the aliphatic polyester in a fertilized state. A slow-release fertilizer containing a biodegradable polymer component and a fertilizer component containing at least one of an organic fertilizer and an inorganic fertilizer has a film strength capable of withstanding physical damage during production. At the same time, the present invention has been completed based on the new finding that long-term stable release is possible in both soil and water. Here, biodegradable means that in one process of degradation, the metabolism of living organisms is involved,
It refers to the property of converting into a low molecular weight compound. The alkyl in the 2-hydroxy-2-alkylacetic acid unit can be hydrogen, methyl, or ethyl, but when all of the alkyls are methyl, that is, poly-2-hydroxy-2-methylacetic acid. It is desirable that Since the aliphatic polyester and the decomposition accelerator are contained in the biodegradable polymer component, even when the molecular weight of the aliphatic polyester is set to be high, in the fertilized state, the decomposition of the aliphatic polyester is prevented. It can be easily promoted.

In addition, by making 60 mol% or more of the alkyl in the 2-hydroxy-2-alkylacetic acid unit a methyl, a proper film strength can be obtained.
In the middle stage of fertilization, hydrolysis of the 2-hydroxy-2-alkylacetic acid unit can be promoted in soil and the like.

After fertilization, the decomposition accelerator completely hydrolyzes the aliphatic polyester in the soil or in the water, so that no substances that exert a load on the environment remain.

As the decomposition accelerator, a decomposition accelerator containing at least one of a transition metal, a transition metal oxide, a transition metal halide, an inorganic acid transition metal salt, and an organic acid transition metal salt is used. Is possible.

The molar ratio of the L-form to the D-form in the 2-hydroxy-2-alkylacetic acid unit is preferably 6 or less in order to ensure solubility in a solvent, biodegradability and hydrolyzability. . Further, it is preferably 3 or more in order to have a predetermined coating strength. Therefore, the molar ratio of the L-form to the D-form in the 2-hydroxy-2-alkylacetic acid unit is preferably from 1: 3 to 1: 6. The structure of the alkyl group in the 2-hydroxy-2-alkylacetic acid unit can be measured by an existing measurement method, and can be measured by, for example, NMR. In addition, an existing measurement method can be used for the method of discriminating and recognizing the L-form and the D-form in the 2-hydroxy-2-alkylacetic acid unit. For example, it can be measured by a polarimeter. .

The aliphatic polyester desirably has a reduced viscosity of 0.15 dl / g or more in order to form a film strength that can withstand use in soil or water.
From the viewpoint of maintaining good production efficiency, the content is desirably 1.0 dl / g or less. Here, the reduced viscosity is obtained by dissolving 0.125 g of aliphatic polyester in 25 ml of chloroform,
It can be measured at 25 ° C. using an Ubbelohde viscosity tube.

Further, by coating a fertilizer component containing at least one of an organic fertilizer and an inorganic fertilizer with a coating material containing the biodegradable polymer component, it can be slowly applied to an easily versatile shape. The fertilizer can be molded, and accurate release can be performed in soil and the like.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION An aliphatic polyester in which at least 60 mol% of alkyl in a 2-hydroxy-2-alkylacetic acid unit is methyl, and a decomposition accelerator which promotes the decomposition of the aliphatic polyester in a fertilized state. The slow-release fertilizer according to the present invention can be obtained by incorporating a biodegradable polymer component and a fertilizer component containing at least one of an organic fertilizer and an inorganic fertilizer.

As the decomposition accelerator, a decomposition accelerator containing at least one of a transition metal, a transition metal oxide, a transition metal halide, an inorganic acid transition metal salt and an organic acid transition metal salt is used. be able to. The transition metal is, for example, Cu, Ag, Zn, Mn, Fe, C
Fine powder metal such as o, Mo, Ni, etc. can be used. Further, as the transition metal oxide, for example, anatase type titanium oxide, chrome green oxide, cobalt blue, or the like can be used. The transition metal halide is, for example, FeCl ₂ , FeCl ₃ , N
iCl ₂ , NiBr ₂ , CoBr ₃ , MnCl ₂ , MnCl
₃ , TiCl ₄ , CuCl, ZnCl _{2 and the} like can be used. In addition, as the inorganic acid transition metal salt, for example, sulfuric acid, sulfurous acid, nitric acid, nitrous acid, carbonic acid, phosphoric acid, phosphorous acid and finely pulverized salts such as Zn, Mo, Mn, Fe, Co, Ni, and Cu are used. be able to. Further, the organic acid transition metal salt is, for example, an organic acid having 1 to 22 carbon atoms,
That is, transition metal salts of saturated, unsaturated, aliphatic carboxylic acids and aromatic carboxylic acids can be used. Incidentally, by appropriately changing the amount of the oxidative decomposition accelerating substance to be added, the release rate according to the intended use can be obtained.

The decomposition accelerator is desirably added in an amount of 0.001 to 20% by weight based on the aliphatic polyester. An addition amount of 20 wt% or more is not appropriate because overheating during production may cause deterioration of the coating. Also,
If the amount is less than 0.001 wt%, the effect of promoting oxidation is insufficient. The decomposition accelerator is preferably added in an amount of 0.05 to 15% by weight based on the aliphatic polyester.

The polymerization of the aliphatic polyester can be carried out by various known methods. For example, when lactide which is a cyclic dimer of lactic acid is used, it can be synthesized by ring-opening addition polymerization, and when lactic acid monomer is used, it can be directly synthesized by dehydration condensation polymerization. Can be. The aliphatic polyester preferably has a molecular weight of 10,000 to 500,000.

The aliphatic polyester in the present invention includes:
Lactic acid, caprolactone, valerolactone, lactones such as butyrolactone, succinic acid, adipic acid, sebacic acid, aliphatic dibasic acids such as azelaic acid, and further copolymerized with polyalkylene glycols such as polyethylene glycol and polypropylene glycol, It is possible to control physical properties.

It is also possible to control the moisture permeability by copolymerizing a polyolefin, a thermoplastic resin having an unsaturated bond, or the like. In addition, the resin properties can be controlled by coexisting other components according to the purpose, and the coexisting components and methods are not limited. Incidentally, by appropriately adjusting the relative amounts of the aliphatic polyester and the decomposition accelerator, it is possible to obtain a release rate according to the intended use.

The fertilizer components used in the present invention include ammonium sulfate, ammonium nitrate, urea, sodium nitrate, isobutyraldehyde condensed urea, potassium phosphate, lime phosphate, calcined phosphorus fertilizer, potassium chloride, potassium sulfate, potassium bicarbonate, Various inorganic and organic fertilizers such as potassium phosphate and potassium nitrate can be used alone or in combination of two or more.

Further, the form of the coated granular fertilizer determines the amount of the fertilizer component to be contained in the composition in order to meet the required performance such as the controlled release concentration and the controlled release period of the fertilizer component, and the convenience at the time of application work. Considering this, it can be formed into a granular shape, a spherical shape, a columnar shape, and a disk shape.

The method of coating the biodegradable polymer on the fertilizer includes a method of kneading and molding into pellets and sheets, and a method of sealing the resin after filling the fertilizer component with a capsule and filling the resin. Although not limited, for example, in the spouted bed, the coating material solution is sprayed on the fertilizer component granules in the rolling or fluidized state, and simultaneously the hot air is blown at a high speed to quickly evaporate and dry the solvent.
Those capable of coating the fertilizer component with a resin are preferred. However, since the biodegradable polymer may be decomposed or deteriorated by heat, it is necessary to control the temperature to a temperature lower than the thermal decomposition temperature or the deterioration temperature in processes such as mixing and kneading, molding, coating material spraying, and drying.

Examples of the form of the biodegradable polymer spray-coated on the fertilizer component include a solution in which the polymer is dissolved in a chlorinated solvent such as trichloroethylene and perchlorethylene, a general-purpose solvent such as toluene and xylene, a molten polymer, and a water-dispersible polymer. The body can be considered, and there is no particular limitation.

The slow-release fertilizer is formed by coating the fertilizer component with a coating material containing the biodegradable polymer component. The fertilizer component is dispersed in the biodegradable polymer component. It may be a slow-release fertilizer.

In the present invention, it is possible to use a powder filler as an additive in addition to the biodegradable polymer component and the fertilizer component as long as the function of controlling the elution of the fertilizer component is not lost. . The powder filler,
It is a hardly water-soluble or water-insoluble powder, and any inorganic or organic powder can be used. The powder filler is uniformly dispersed in the coating, but those having poor dispersibility require a surface treatment with silicon or the like, or a dispersibility improving treatment such as easy dispersion with a surfactant or the like. Preferred materials for the inorganic powder filler include, for example, talc, calcium carbonate, clay, diatomaceous earth, silica and salts thereof,
Examples include metal oxides and sulfur. Of these inorganic powder fillers, sulfur is a material that is subject to microbial degradation, and has the advantage of being more susceptible to degradation in soil as a component of the composite material of the coating. On the other hand, organic powder fillers are often decomposed by microorganisms, and soil decomposition as a composite material is superior to sulfur.For example, starch and other starchy materials, and Aonmonium in soil by microbial decomposition Clotilidene diurea, which produces ions, is a preferred material.

When the powder filler is used, the strength of the biodegradable polymer component tends to decrease as the amount of the filler increases. Therefore, the amount of the powder filler used in the slow-release fertilizer is preferably 10 to 60% by weight.

In addition to the fertilizer component and the biodegradable polymer component, one or a combination of two or more agricultural chemical components such as herbicides, insecticides, and fungicides can be used depending on the intended use. The agrochemical components include tricyclazole, metasulfocarb, pyrazolate, bromotide, butachlor, diazinon, benzoepin, BPMC
(Bassa), NAC (Sevin), Acephate (Ortran), Fention (Vigit), 2,4-D
(2,4-PA), MCPB, CNP, phenothiol, esprocarb, and the like can be used, but are not limited thereto, and one or a mixture of two or more can be used. .

In the present invention, in addition to the biodegradable polymer component and the fertilizer component, a surfactant may be used as an additive as long as the elution control function of the fertilizer component is not lost. It is. As the surfactant, any of cationic, anionic, amphoteric and nonionic surfactants can be used.

If the hydrophilicity is too strong, the surfactant is not uniformly dispersed in the coating and agglomerates to cause a coating defect. On the other hand, if the lipophilicity is too strong, the surfactant has little effect on the coating. In addition, the effect of promoting the dissolution of fertilizer components tends to be poor. Therefore, the balance of hydrophilicity and hydrophobicity of the surfactant is important.

[0040]

EXAMPLES Examples of the present invention will be described below. (Example 1) 200 g of DL-lactide (L / D = 6),
A toluene solution of 1.521 g of glycolic acid and 0.1 g of aluminum acetylacetonate as a ring-opening polymerization catalyst was charged into a four-necked flask equipped with a nitrogen inlet tube, and heated to 190 ° C. under a nitrogen atmosphere to effect ring-opening polymerization. Thus, an aliphatic polyester was obtained.

After dissolving 10 parts of the aliphatic polyester in 200 parts by weight of trichloroethylene and adding 0.1 part by weight of anatase-type titanium oxide, the nitrogen-based granular fertilizer component having an average particle diameter of 4 mm was sprayed using a jet coating apparatus. Spray coating,
The solvent was evaporated and dried with high-temperature hot air to produce coated granular slow-release fertilizer. (Example 2) 100 parts by weight of DL-lactide, 25 parts by weight of polyisoprene polyol (number average molecular weight Mn = 2500), 0.1 part by weight of tin octylate, and 10 parts of anhydrous xylene
0 parts by weight was put into a polymerization tube equipped with a nitrogen introduction tube, heated and stirred at 140 ° C. under a nitrogen atmosphere, and subjected to ring-opening polymerization for 20 hours. Thereafter, xylene was distilled off at 165 ° C. to remove the aliphatic polyester. Obtained. Then, a coated granular slow-release fertilizer was produced from this aliphatic polyester in the same manner as in Example 1. (Example 3) 200 g of DL-lactide (L / D = 3),
A toluene solution of 1.521 g of glycolic acid and 0.1 g of aluminum acetylacetonate as a ring-opening polymerization catalyst was charged into a four-necked flask equipped with a nitrogen inlet tube, and heated to 190 ° C. under a nitrogen atmosphere to effect ring-opening polymerization. Subsequently, 2.4017 g of succinic anhydride was added and reacted for 1 hour.
Further, magnesium acetylacenate 2.2252
g was added thereto, and the mixture was evacuated and reacted at 190 ° C. for 1 hour to obtain an aliphatic polyester. Then, a coated granular slow-release fertilizer was produced from this aliphatic polyester in the same manner as in Example 1. (Comparative Example) Low-density polyethylene (MI (melt index) = 23, density 0.916) as a resin for a coating agent
g / cm ³ ), 10 parts by weight of trichloroethylene 200
Dissolved in an amount of 0.001 by weight of anatase type titanium oxide.
After the addition by weight, a nitrogen-based granular fertilizer component having an average particle size of 4 mm was spray-coated using a jet coating device, and the solvent was evaporated and dried with high-temperature hot air to produce a coated granular slow-release fertilizer.

In the coated granular fertilizer obtained in each of Example 1, Example 2, Example 3, and Comparative Example, the elution rate (%) of the agricultural active ingredient was measured. 4. each coated granular fertilizer
0 g is immersed in 200 ml of water and allowed to stand at 25 ° C. After a predetermined period, fertilizer components and water were separated, and urea eluted in the water was determined by quantitative analysis. 200 ml of fresh water was added to the fertilizer component, and the mixture was allowed to stand at 25 ° C. again. By repeating such an operation, the relationship between the total dissolution of urea eluted in water and the number of days was obtained. The dissolution rate (%) of the agricultural active ingredient was relatively measured from the total dissolution of urea. The results are shown in Table 1 below.

[0043]

[Table 1]

From the results shown in Table 1 above, the slow-release fertilizer according to the present invention did not burst in the early stage of fertilization and achieved a high elution rate of nitrogen components into pure water as the number of days passed. We were able to. After fertilization,
The decomposition of the polymer component did not affect the environment in soil or the like. On the other hand, in the slow-release fertilizer according to the comparative example, the elution rate of the nitrogen component into pure water was low even after a lapse of days, and the effect of eluting the fertilizer component into soil or the like was low.

The embodiments and examples disclosed this time are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

[0046]

The polymer used in the present invention has the effect of hydrolyzing the aliphatic polyester segment, oxidatively decomposing the unsaturated hydrocarbon polymer segment, and decomposing microorganisms in the soil. It is possible to arbitrarily control the release period for the intended use while suppressing the release. Further, after fertilization, the biodegradable polymer component is easily decomposed, so that no substance that exerts a load on the environment is left in soil or water.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Takashi Miyamoto 2-1-1 Katata, Otsu-shi, Shiga Prefecture Inside Toyobo Co., Ltd. Research Institute (72) Inventor Takeshi Ito 2-1-1 Katata, Otsu-shi, Shiga Prefecture Inside Toyobo Co., Ltd. (72) Inventor Katsuya Shidano 2-1-1 Katata, Otsu-shi, Shiga Prefecture Inside Toyobo Co., Ltd. (72) Inventor Yasunori Hotta 2-1-1 Katata, Otsu-shi, Shiga Prefecture No. F-term in Toyobo Co., Ltd. Research Laboratory 4H061 AA01 DD04 DD18 DD20 EE11 EE15 EE16 EE17 EE19 EE27 EE35 FF15 HH03 LL13 LL26 LL26 4J029 AA02 AB07 AC01 AC02 AD01 AE18 EA05

Claims (5)

[Claims] 1. A raw material comprising an aliphatic polyester in which at least 60 mol% of alkyl in a 2-hydroxy-2-alkylacetic acid unit is methyl, and a decomposition accelerator for accelerating the decomposition of the aliphatic polyester in a fertilized state. A slow-release fertilizer containing a degradable polymer component and a fertilizer component containing at least one of an organic fertilizer and an inorganic fertilizer. 2. The decomposition accelerator is a decomposition accelerator containing at least one of a transition metal, a transition metal oxide, a transition metal halide, an inorganic acid transition metal salt, and an organic acid transition metal salt. The slow-release fertilizer according to claim 1. 3. The molar ratio of L-form to D-form in the 2-hydroxy-2-alkylacetic acid unit is from 1: 3 to 1: 6.
The slow-release fertilizer according to claim 1 or 2, wherein 4. The slow-release fertilizer according to claim 1, wherein the aliphatic polyester has a reduced viscosity of 0.15 to 1.0 dl / g. 5. The slow-release fertilizer according to claim 1, wherein the fertilizer component is coated with a coating material containing the biodegradable polymer component.