JP2001064089A - Slow-acting fertilizer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to control the biodegradation and hydrolysis rate of a polymer and eventually to arbitrary control the slow-acting rate of fertilizer components while preventing an initial burst in spite of a biodegradable resin alone by consisting the fertilizer of an aliphatic polyester having specific structural units and containing at least >=1 kind of metals in the main chain in a specific concentration range and fertilizer components. SOLUTION: The aliphatic polyester has the structural units of the formula and contains at least >=1 kind of the metals in the main chain in the concentration range of 10 to 300 eq/106 g. In the formula, R denotes H or a 1-3C alkyl group and (n) denotes an integer from 0 to 4. Among the structural units of the formula, >=60 mol% are lactic acid residues and the molar ratio L/D of L-lactic acid to D-lactic acid is preferably 1 to 9. The metals are incorporated into the aliphatic polyester, by which the carboxylic acid group at the terminal of the aliphatic polyester and the metals are ionicalled bonded, the molecules of the aliphatic polyester are chain-extended and the degradability of the aliphatic polyester may be regulated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for preparing a fertilizer component by combining a specific aliphatic polyester and a fertilizer component, preferably by coating the fertilizer component with a specific aliphatic polyester. At a concentration, the fertilizer component is gradually released into the surrounding soil or water for an arbitrary period, and after fertilization, the resin component is decomposed, and a substance that exerts a load on the environment is not left in the soil. About effective fertilizer.

[0002]

2. Description of the Related Art Fertilizers are often used for increasing crop production in agriculture, but those that lose their effectiveness in a short period of time have a large number of fertilizations, resulting in a decrease in workability and cost. It is effective to coat the fertilizer component with a suitable resin and microencapsulate it for the purpose of maintaining the efficacy for a long period of time, and various such granular fertilizers have been devised. Furthermore, various examples have been reported in which a biodegradable resin is used as a resin component in consideration of the effect on the environment such as resin residue after fertilization.

Examples of using biodegradable resin include polylactic acid type (Japanese Patent Application Laid-Open No. Hei 7-061884) and polycaprolactone type (Japanese Patent Application Laid-Open No. 10-101501). As a compounding example of a hardly decomposable resin or a resin having low moisture permeability, a compound of a biodegradable resin, a low molecular weight polyolefin, and a wax (Japanese Patent Application Laid-Open No. 9-263476) has been proposed.

[0004]

However, when a biodegradable resin is used in combination with a hardly decomposable resin, the hardly decomposable component remains in soil or water even after fertilization, which adversely affects the environment. In addition, when a biodegradable resin is used alone, it is difficult to achieve both degradability and film strength sufficient for sustained release of a fertilizer component over a long period of time. Insufficient coating strength causes a so-called burst phenomenon in which a large amount of fertilizer components are eluted from the damaged portion at the beginning of fertilization due to damage caused by physical impact during production and transportation. Furthermore, when a biodegradable resin is used in a blend composition of a plurality of types, it is easy to become a non-uniform film, and it is difficult to secure sufficient film strength.
There are problems such as causing an initial burst.

[0005]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that when a fertilizer component is coated with a specific aliphatic polyester, a metal compound is contained in the main chain of the polymer. Biodegradation of the polymer,
The hydrolysis rate was controlled, and as a result, it was found that the sustained release rate of the fertilizer component could be arbitrarily controlled while preventing the initial burst while using only the biodegradable resin. The aliphatic polyester in the present invention can release the fertilizer component at an arbitrary concentration and for a desired period of time by hydrolysis at an appropriate rate during fertilization, and after fertilization, is hydrolyzed or biodegraded in soil or Since it disappears in water, substances that have an impact on the environment do not remain in the soil.

That is, the present invention is a slow-release fertilizer comprising an aliphatic polyester and a fertilizer component as essential components.

In the present invention, at least one metal is contained in the main chain of the aliphatic polyester in an amount of 10 to 300 eq / 10 ⁶ g.
In the concentration range of

In the structural unit of the following formula (1), at least 60 mol% is a lactic acid residue, and the molar ratio of L-lactic acid to D-lactic acid is L
/ D can be in the range of 1-9.

[0009]

Embedded image

In particular, of the structural units of the formula (1), at least 60 mol% are lactic acid residues and the molar ratio L / D of L-lactic acid to D-lactic acid is 3
It can be in the range of ~ 6.

Further, the fertilizer can be a slow-release fertilizer characterized in that the fertilizer component is coated with an aliphatic polyester.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION

The aliphatic polyester in the present invention desirably has a lactic acid residue of 60 mol% or more in order to have a film forming ability as a coating resin and an appropriate hydrolyzability. From a cost standpoint, those having 100 mol% of lactic acid residues are also particularly preferred. The L / D molar ratio of the lactic acid monomer is preferably 1 or more in order to satisfy the film strength and cost that can withstand application, and 9 or less in terms of ensuring solubility in a solvent, biodegradability, and hydrolyzability. More preferably, the L / D molar ratio is 3-6. The amount of lactic acid residue is measured by NMR, and the molar ratio L / D between L-lactic acid and D-lactic acid is measured by a polarimeter.

The aliphatic polyester used in the present invention preferably has a reduced viscosity of 0.15 dl / g or more in order to form a film that can be used in soil or water. The term "reduced viscosity" as used herein refers to a value obtained by dissolving 0.125 g of a polymer in 25 ml of chloroform and measuring at 25 ° C. using an Ubbelohde viscosity tube.

The aliphatic polyester used in the present invention contains a metal in the main chain. By containing the metal, the carboxylic acid group at the terminal of the aliphatic polyester and the metal are ion-bonded, the chain of the aliphatic polyester is extended, and the decomposability of the aliphatic polyester can be adjusted.

In the present invention, the metal which can be contained in the main chain includes magnesium, calcium,
Copper, tin, zinc, iron, manganese, barium, aluminum, cobalt, nickel, strontium, indium, sodium, potassium, titanium, vanadium, etc.
Although a trivalent metal is mentioned, it is particularly preferable to use a divalent metal. Even when a monovalent metal is used alone, chain extension of the main chain is impossible, and when a trivalent metal is used alone,
When used in a large amount, there is a risk that the resin gels and a desired film cannot be obtained. Further, among the divalent metals, calcium and magnesium are particularly preferable in that the load on the environment can be reduced as much as possible.

The divalent metal compounds usable in the present invention include magnesium compounds such as magnesium acetate, magnesium octylate, magnesium stearate, magnesium acetylacetonate, calcium acetate, calcium lactate, calcium stearate, calcium acetylacetonate. And the like, calcium compounds, and the like. These can be used alone or in combination of two or more, but from the viewpoint of the reactivity, physical properties of the resulting film, etc., particularly calcium acetylacetonate,
Magnesium acetylacetonate is desirable.

[0018] The range of concentration of the metal compound used is preferably 10~300eq / 10 ⁶ g. 10eq / 10 ⁶ g
The following concentrations, biodegradation of the polymer, can not be expected the effect of increasing the hydrolysis rate, and when more than 300eq / 10 ⁶ g is either solubility in solvent is deteriorated due to aggregation other reasons, dissolved However, it is not possible to obtain a film property that can withstand use as a coating agent, such as an extremely high hydrolysis rate.

The aliphatic polyester of the present invention controls the acid value and controls the concentration and duration of the controlled release of the fertilizer component according to the requirements of the intended use by selecting the concentration and type of the metal to be contained. can do.

Examples of the method for incorporating a metal into a polymer include a method in which a metal compound is charged all at once at the start of polymer polymerization and copolymerization, and a method in which a metal compound is added to a polymer prepared in advance and the chain is extended into a main chain by a chain extension reaction. Examples include a method of incorporating a metal compound, and the production method is not limited.

The aliphatic polyester in the present invention includes:
In addition to lactic acid, lactones such as caprolactone, valerolactone, butyrolactone, succinic acid,
Physical properties can be controlled by copolymerizing aliphatic dibasic acids such as adipic acid, sebacic acid and azelaic acid, and polyalkylene glycols such as polyethylene glycol and polypropylene glycol. 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 depending on the purpose, and the coexisting components and methods are not limited.

The fertilizer component that can be used in the present invention is not particularly limited, and inorganic and organic fertilizers can be used alone or in combination of two or more. Herbicides depending on the application,
Agrochemical active ingredients such as insecticides and fungicides can be used alone or in combination of two or more.

The form of the coated fertilizer is determined in consideration of the amount of the fertilizer component to be contained in the composition in order to meet the required performance such as the sustained release concentration of the fertilizer component, the sustained release period, etc., and the convenience at the time of application. Granules, spheres, columns, capsules, and the like can be selected, but there is no particular limitation, and there is no limitation on the size, particle size, or the like.

Examples of the method of coating the fertilizer component with the aliphatic polyester include a method of kneading and molding into a pellet shape, a sheet shape, and the like, a method of filling the fertilizer component with a resin in a capsule shape, and sealing the resin. In terms of high-precision control of the sustained release rate, for example, in a spouted bed, the coating solution is sprayed on the fertilizer component granules in a rolling or fluidized state, and at the same time, the solvent is rapidly blown by blowing hot air at a high speed. A method of coating the surface of the fertilizer component with a resin, such as a method of evaporating and drying, is particularly preferred. However, since the biodegradable polymer may be decomposed or deteriorated by heat, the product temperature is controlled to be lower than the thermal decomposition or thermal degradation temperature of the component in the process of mixing and kneading, molding, coating agent spraying, and drying. There is a need.

Examples of the form of the aliphatic polyester to be spray-coated on the fertilizer component include a solution obtained by dissolving the polymer in a general solvent such as toluene and xylene in addition to a halogen-containing solvent such as trichloroethylene and perchloroethylene, or a molten polymer. It is conceivable, however, that the aqueous dispersion can be used if necessary, such as a requirement for temperature setting depending on the composition of the polymer and the type of the pesticidal active ingredient, and the form is not limited. Preparation of the aqueous dispersion, the polyester is dissolved in a hydrophilic solvent,
The method can be carried out by adding a surfactant and water and then distilling off the hydrophilic solvent. However, from the viewpoint of simplicity of preparation of the coating agent, a method using a solution or a molten polymer is more desirable.

[0026]

EXAMPLES Examples of the present invention will be described below, but they are merely examples, and the present invention is not limited thereto.

Example 1 DL-lactide 200 g, calcium lactate 1.232 g (20 eq / 10
⁶ g), a toluene solution of 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. in a nitrogen atmosphere to cause ring-opening polymerization and aliphatic polyester. (1) was obtained. Table 1 shows the measured physical properties of the obtained polyester.

The aliphatic polyester (1) is dissolved in trichloroethylene at a concentration of 5% w / w, spray-coated on a nitrogen-based granular fertilizer using a jet coating device, and the solvent is evaporated and dried by high-temperature hot air to obtain a coated granular fertilizer ( 1) was prepared.

Example 2 DL-lactide 200 g, glycolic acid 1.521 g (100 eq / 10
⁶ g), a toluene solution of 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 perform ring-opening polymerization, and then anhydrous. 1.9213 g of succinic acid was added and reacted for 1 hour. Further magnesium acetylacetonate
2.2252 g (50 eq / 10 ⁶ g) was added and reacted at 190 ° C. for 1 hour under vacuum to obtain an aliphatic polyester (2). Table 1 shows the measured physical properties of the obtained copolyester.

The aliphatic polyester (2) was coated in the same manner as in Example 1 to obtain a coated granular fertilizer (2).

Example 3 180 g of DL-lactide, 20 g of glycolide, 2.46 of calcium lactate
A toluene solution of 5 g (40 eq / 10 ⁶ g) 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 aliphatic polyester (1)
An aliphatic polyester (3) was obtained in the same manner as described above. Table 1 shows the measured physical properties of the obtained polyester.

[0032]

[Table 1]

The aliphatic polyester (3) was coated in the same manner as in Example 1 to obtain a coated granular fertilizer (3).

Comparative Example A low density polyethylene (MI = 23, d = 0.916 g /
cm3) to produce coated granular fertilizer (4) in the same manner as aliphatic polyester (1).

The prepared coated granular pesticide was added to 200 g of water in 5.0 g.
g, and the elution rate of nitrogen into pure water was measured. Table 2 shows the results.

[0036]

[Table 2]

[0037]

As a specific effect of the present invention, the resin used in the present invention contains a metal compound to improve the rate of hydrolysis, so that the fertilizer component according to the requirements at the time of fertilization can be used. The controlled release rate can be controlled with high precision, and after application, it does not remain in the soil or water for a long time due to hydrolysis and biodegradation, and thus does not impose a burden on the environment.

Continued on the front page (72) Inventor Katsuya Shidano 2-1-1 Katata, Otsu-shi, Shiga Prefecture Toyobo Research Co., Ltd. (72) Inventor Yasutori Hotta 2-1-1 Katata, Otsu-shi, Shiga Toyobo F-term in the Research Institute, Inc. (Reference) 4H061 AA01 DD04 DD18 EE32 EE35 HH03 HH32 LL26 LL30 4J029 AA02 AB07 AC01 AC02 AD01 AD07 AE18 EH03 JB112 JB113 JB172 JB173 JF032 JF033 JF042 JF043 JF07F182 J133 JF223 JF242 JF243 JF322 JF323 JF372 JF373 JF422 JF423 JF542 JF543 JF562 JF563 JF572 JF573 KB03 KB04

Claims (4)

[Claims] [Claim 1] (Wherein, R represents H or an alkyl group having 1 to 3 carbon atoms,
n represents an integer of 0 to 4) an aliphatic polyester having the structural unit of the above formula (1) and containing at least one or more metals in the main chain in a concentration range of 10 to 300 eq / 10 ⁶ g. A slow-release fertilizer comprising a fertilizer component. (2) In the structural unit of the above formula (1), 60 mol% or more is a lactic acid residue, and the molar ratio L / D of L-lactic acid to D-lactic acid is 1 to 2.
2. The slow-release fertilizer according to claim 1, wherein the fertilizer is an aliphatic polyester within the range of 9. 3. The slow-release fertilizer according to claim 2, wherein the molar ratio L / D of L-lactic acid to D-lactic acid in the aliphatic polyester is in the range of 3 to 6. fertilizer. 4. The coated granular fertilizer according to claim 1, wherein the fertilizer component is coated with an aliphatic polyester.