JPH11263689A - Coated fertilizer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a coated fertilizer having a coating material which gives a wide range to control elution of the fertilizer component, which has excellent film strength and which is biodegradable in soil after elution of the fertilizer is completed, by coating a fertilizer with a coating material containing an aliphatic polyester and a microwax in a specified ratio. SOLUTION: The coated fertilizer is coated with a coating material containing 20 to 90 wt.% aliphatic polyester and 10 to 80 wt.% microwax. As for the aliphatic polyester, the following compds. can be used. They are, for example, (1) homopolymers of aliphatic polyesters and/or copolymers of aliphatic copolyesters, (2) homopolymer polyhydroxycarboxylic acids and/or copolymer copolyhydroxycarboxylic acids, (3) polycaprolactone, (4) polylactic acid, (5) polybutylene succinate, (6) mixtures of (1) to (5), (7) polymer blends of (1) to (5), (8) polymer alloys of (1) to (5). The microwax is the abbreviation of a microcrystalline wax.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a coated fertilizer using a novel coating material. More particularly, the present invention relates to a coated fertilizer in which the coating material is made of a biodegradable material and the decomposition of the coating material in the environment after elution of the fertilizer component.

[0002]

2. Description of the Related Art [Technical background of coated fertilizer] Coated fertilizer is a kind of slow-release fertilizer in which the fertilizer component is wrapped in plastic or the like.
Reduce the number of fertilizations, save labor and eliminate excess fertilization,
The burden on the environment can be reduced. Hitherto, it has been studied to control the dissolution rate of fertilizer components by coating various fertilizers with plastics. For example,
No.-89 discloses a method for producing a coated fertilizer by dissolving a polyolefin-based plastic such as low-density polyethylene or ethylene-vinyl acetate copolymer in an organic chlorine-based solvent such as tetrachloroethylene, spraying and drying the fertilizer. ing. Further, an attempt to disintegrate these polyolefin-based plastics by natural light or the like has been proposed in, for example, Japanese Patent Publication No. 23516/1990. However, they have the disadvantage that the membrane shells remain and accumulate in the soil after elution of the fertilizer components, since they are not essentially biodegradable plastics.

[0003] For example, Japanese Patent Publication No. 23535/1995 and Japanese Patent Laid-Open Publication No. 7-33577 disclose a fertilizer coated with a biodegradable plastic such as polycaprolactone or polylactic acid, and a membrane after elution of the fertilizer component. A biodegradable plastic-coated fertilizer has been proposed in which shells are completely decomposed by microorganisms and do not remain in soil. However, since the biodegradable plastic has high water vapor permeability, the coating of the biodegradable resin alone has a high elution rate of the fertilizer component, and cannot be applied to a long-term elution control type fertilizer. As a method of solving this, for example, Japanese Patent Publication No. 23517/1990, Japanese Patent Application Laid-Open No. 4-89384, Japanese Patent Application Laid-Open No. 5-85873,
JP-A-7-33576 and JP-B-7-505 propose a method of mixing a biodegradable plastic with another non-biodegradable plastic for the purpose of suppressing elution. However, even if these materials do not have a high ratio of biodegradable plastics, they cannot exhibit sufficient biodegradability. However, it has a drawback that it cannot be applied to coated fertilizers.

Further, a method of forming a multilayer coating structure is disclosed in JP-A-7-33576, JP-A-7-133179, JP-A-8-2989, and JP-A-9-19428.
Japanese Patent Application Laid-Open No. 6-157181 proposes a method of using a biodegradable resin as a binder for fertilizer and coating the biodegradable resin with a biodegradable resin. It was not efficient.

Further, a method of mixing a low-molecular resinous substance such as paraffin wax with a biodegradable plastic is described in Japanese Patent Publication No. 23517/1995, Japanese Patent Publication 7-505 / 1995, and Japanese Patent Application Laid-Open No. 7-61884. Also, a method of mixing polyethylene wax is disclosed in JP-A-9-26347.
No. 6. In order to reduce the water vapor permeability by these methods and obtain a long-term elution-type coated fertilizer, it is necessary to mix a large amount of low-molecular resinous substances or polyethylene wax, and the ratio of biodegradable plastic decreases. Although the biodegradability of the coating may not be impaired, the strength of the coating will decrease, and the coating will be damaged due to the impact of filling in bags or blending with other fertilizers. There was a disadvantage that the fertilizer elution period was shortened.

[0006] increasing the amount of coating material used for fertilizer,
The method of increasing the film thickness to suppress dissolution and improve the strength of the film is not preferable because the production time becomes longer, the cost of the product increases, and the content of the fertilizer component decreases. Further, in order to maintain the strength of the coating, for example, if a polyethylene wax having a high molecular weight is used, the biodegradability of the coating is impaired. None of the above-mentioned conventional coated fertilizers can simultaneously satisfy the biodegradability of the coating in soil, a wide range of elution control, and the strength of the coating.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a coated fertilizer which has a wide range of control over elution of fertilizer components, has excellent coating strength, and in which the coating material biodegrades in soil after the elution is completed. I do.

[0008]

Means for Solving the Problems As a result of intensive studies on the above-mentioned problems, the present inventors have found an excellent effect of reducing the water vapor permeability of microwax to aliphatic polyester, and have found that a small amount of water can be mixed with aliphatic polyester. Thus, a long-term elution-type coated fertilizer was obtained without lowering the coating strength, thereby completing the present invention.

The invention according to the present application is as described below. 20% by weight or more and 90% by weight or less of aliphatic polyester,
And a coated fertilizer having a coating layer containing 10% by weight or more and 80% by weight or less of microwax. The coated fertilizer according to the above, wherein the aliphatic polyester is polycaprolactone. The coated fertilizer according to the above description, wherein the aliphatic polyester is lactic acid and / or a copolymer of lactic acid and another hydroxycarboxylic acid other than lactic acid. The coated fertilizer according to the above, wherein the aliphatic polyester is a polyester of lactic acid and / or an aliphatic polyhydric alcohol and an aliphatic polyhydric carboxylic acid. The coated fertilizer according to claim, wherein the aliphatic polyester is a polyester of an aliphatic polyhydric alcohol and an aliphatic polycarboxylic acid. When the aliphatic polyhydric alcohol is ethylene glycol and / or
Or 1,4-butanediol or the coated fertilizer according to the above. The coated fertilizer as described in or described above, wherein the aliphatic polycarboxylic acid is succinic acid and / or adipic acid.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The aliphatic polyester according to the present invention is, for example, lactic acid and / or a copolymer of lactic acid and another hydroxycarboxylic acid, lactic acid and / or aliphatic polyhydric alcohol and aliphatic polycarboxylic acid. Or a polyester comprising an aliphatic polyhydric alcohol and an aliphatic polycarboxylic acid, or a copolymer or mixture thereof.

[Microwax] The term "microwax" used in the specification of the present application is based on JIS K
2235 (1991), which is a kind of petroleum wax and is an abbreviation for the term "microcrystalline wax". Microcrystalline wax is a residual oil obtained by distillation of crude oil under reduced pressure, or a wax solid at normal temperature separated and purified from heavy distillate oil. Isoparaffins and cycloparaffinic hydrocarbons having about 35 to 65 carbon atoms are main components and normal paraffins are obtained. Low molecular weight from 500 to 9
It is a mixture of about 00 hydrocarbons.

On the other hand, paraffin wax is a solid wax at normal temperature which is separated and refined from crude oil under reduced pressure distillation and has a molecular weight of 30 as a main component, which is composed of normal paraffin as a main component.
It is a mixture of 0 to 500 hydrocarbons and differs in component and crystal structure from microcrystalline wax. Petroleum waxes such as microwaxes and paraffin waxes are, for example, Bacterium alipaticu
It is known that it is easily decomposed in soil by microorganisms such as M. liquefaciens. It is presumed that the excellent water vapor permeability lowering effect of the microwax on the aliphatic polyester is not merely due to the hydrophobicity of the microwax but due to the difference in the compatibility and the microstructure of the mixture.

[Fertilizer] The term "fertilizer" used in the present application is defined by the Fertilizer Control Law as follows. An object applied to land for the purpose of plant nutrition. What is applied to land for the purpose of bringing about chemical change in soil to contribute to plant cultivation. What is given to plants for the purpose of providing them for nutrition. In the specification of the present application, as long as the fertilizer used as the base material of the plastic coating is solid, the shape of the particles such as the particle size and the particle size distribution and the composition of the fertilizer components such as nitrogen, phosphoric acid, and potassium are not limited.

[Coated fertilizer] The concept of the term "coated fertilizer" used in the specification of the present application is that the surface of the fertilizer is coated (coated) with plastic or the like, and the elution rate of the fertilizer component in soil is adjusted. It is a fertilizer that aims to maintain, slow the release of the fertilizer, and prevent the runoff of fertilizer components. The initial dissolution rate of fertilizer components (dissolution rate in 24 hours in still water) is regulated by the Fertilizer Control Law to be 50% or less. The types of coated fertilizers include coated potassium fertilizer, coated nitrogen fertilizer, and coated composite fertilizer.

[Aliphatic polyester] The term "aliphatic polyester" used in the specification of the present application includes an aliphatic polyester which is a homopolymer and / or an aliphatic copolyester which is a copolymer. The term “aliphatic polyester” used in the specification of the present application includes an aliphatic polyester in which an aliphatic polyhydric carboxylic acid and an aliphatic polyhydric alcohol are dehydrated and condensed, and a polyhydroxycarboxylic acid. The term "aliphatic polyester" as used in the specification of the present application includes at least a part thereof which is crosslinked. The term "aliphatic polyester" as used in the specification of the present application also includes those which are at least partially cross-linked by a cross-linking agent such as, for example, a branched compound or a polysaccharide. The term "aliphatic polyester" as used in the specification of the present application also includes at least partially branched ones. The term "aliphatic polyester" used in the specification of the present application refers to not only one kind but also a polymer multiphase system such as a polymer blend or a polymer alloy of two or more kinds, or a partially reacted copolymer. Is also included. Of course, a compatibilizer may be present in such a polymer multiphase system in order to improve compatibility.

The term "polyhydroxycarboxylic acid" as used in the specification of the present application includes polyhydroxycarboxylic acid which is a homopolymer and / or copolyhydroxycarboxylic acid which is a copolymer.

The term "polycaprolactone" as used in the specification of the present application includes polycaprolactone as a homopolymer and / or copolycaprolactone as a copolymer.

As used herein, the term "polylactic acid" includes polylactic acid as a homopolymer and / or copolylactic acid as a copolymer. The term "polylactic acid" as used in the specification of the present application also includes those formed from L-lactic acid and / or D-lactic acid.

As used herein, the term "polybutylene succinate" includes polybutylene succinate as a homopolymer and / or copolybutylene succinate as a copolymer. The term “plastic” used in the specification of the present application is defined as “polymer”,
The term includes “copolymer”, “polymer”, “polymer”, “copolymer”, and “resin”.

"Polymer" used in the specification of the present invention
The concept of the term is equivalent to the concept of the term "polymer" and includes homopolymers and copolymers. The mode of arrangement of the copolymer may be any of a random copolymer, an alternating copolymer, a block copolymer, and a graft copolymer. The concept of the term "copolymer" as used in the specification of the present invention is equivalent to the concept of the term "copolymer", and is at least partially linear, cyclic, macrocyclic, branched, star-shaped, tertiary, Any structure such as original mesh, IPN (interpenetrated polymer network), and PIC (polyion complex) may be used.

[Aspect of Aliphatic Polyester] In the specification of the present application, the aliphatic polyester is at least
The following embodiments are included. An aliphatic polyester as a homopolymer and / or an aliphatic copolyester as a copolymer. Homopolymer polyhydroxycarboxylic acid and / or copolyhydroxycarboxylic acid copolymer. Polycaprolactone. Polylactic acid. Polybutylene succinate. A mixture of A polymer blend of Polymer alloy of In the case of the above, a compatibilizer may be contained.

[Method for Producing Aliphatic Polyester] The method for producing the aliphatic polyester used in the present invention is not particularly limited and can be carried out by a known method. Specific examples of the production method include, for example, lactic acid or a method in which lactic acid and another hydroxycarboxylic acid, or a method in which a polyhydric alcohol and a polyhydric carboxylic acid are produced by direct dehydration polycondensation, a polyhydric alcohol and a polyhydric carboxylic acid. A method of producing by subjecting an acid ester to polycondensation by a transesterification reaction, for example, a method obtained by ring-opening polymerization of a cyclic ester compound such as lactide, glycolide, ε-caprolactone or a mixture thereof, polylactic acid and other A method of reacting a polymer of hydroxycarboxylic acid at a high temperature to form a copolymer may be mentioned.

[Molecular Weight of Aliphatic Polyester] The molecular weight or molecular weight distribution of the aliphatic polyester used in the present invention is not particularly limited as long as the coating has desired properties. Generally, a weight average molecular weight of 1,000 to
One million is preferable, and especially 20,000 to 200,000 is preferable. Generally, when the weight average molecular weight is less than 1,000, the coating strength is weak and is not practical. In addition, the weight average molecular weight is 1
If it is larger than 100,000, the viscosity of the resin solution or the melt viscosity of the resin becomes high, and the polymer hardly adheres to the surface of the fertilizer, so that a continuous film cannot be obtained, thereby suppressing the elution of the fertilizer component. It becomes difficult. The weight average molecular weight and the molecular weight distribution of the aliphatic polyester used in the present invention, the polymerization method, the type of solvent, the type and amount of the catalyst, the reaction temperature, the reaction time, the reaction conditions such as the method of removing the condensed water generated. It can be controlled to a desired one by appropriately selecting.

[Polycaprolactone] Polycaprolactone is a kind of biodegradable aliphatic polyester and is produced by ring-opening polymerization of ε-caprolactone. Polycaprolactone has a melting point as low as 60 ° C. as compared to the melting point of poly L-lactic acid of 175 ° C., and is melted at a relatively low temperature.
It has the feature that the processing temperature is low. The polycaprolactone used in the present invention may be a cyclic ester such as lactide or glycolide, an aliphatic hydroxycarboxylic acid, and / or an aliphatic polyhydric alcohol and an aliphatic polycarboxylic acid other than the ε-caprolactone component. It may contain an ester repeating unit. Further, for the purpose of improving physical properties such as heat resistance of polycaprolactone, polyhydroxybutyrate, polybutylene succinate,
One or more aliphatic polyesters such as polyglycolic acid and polylactic acid may be blended and used.

[Polylactic acid] Lactic acid, which is a raw material of polylactic acid, is produced by fermentation or chemical synthesis. In particular, L-lactic acid produced by fermentation has been produced in large quantities and has become available at low cost. Further, the obtained polymer has a characteristic of high rigidity, and thus, it is expected that polymers containing various polylactic acids are used at present.

The polylactic acid used in the present invention may contain, in addition to the lactic acid component, another aliphatic hydroxycarboxylic acid and / or an aliphatic ester composed of an aliphatic polyhydric alcohol and an aliphatic polycarboxylic acid, in particular, other than lactic acid. An aliphatic ester component comprising an aliphatic hydroxycarboxylic acid and / or an aliphatic diol and an aliphatic dicarboxylic acid may be contained. The polylactic acid used in the present invention is polylactic acid, an aliphatic copolyester of lactic acid and an aliphatic hydroxycarboxylic acid other than lactic acid, and an aliphatic copolyester composed of lactic acid, an aliphatic diol and an aliphatic dicarboxylic acid, and a mixture thereof. It may be.

Further, the polylactic acid used in the present invention may be an aliphatic block copolyester containing an aliphatic homo or aliphatic copolyester component of an aliphatic hydroxycarboxylic acid other than polylactic acid, especially polylactic acid and 6-lactic acid. A homo- or copoly 6-hydroxycaproic acid block polyester containing a hydroxycaproic acid component is also an aliphatic copolyester comprising polylactic acid, an aliphatic diol and an aliphatic dicarboxylic acid, particularly polylactic acid and 1,4-butanediol. It may be a block polyester with homo- or copolybutylene succinate containing succinic acid.

Further, a mixture of polylactic acid and an aliphatic polyester of an aliphatic hydroxycarboxylic acid other than lactic acid, or a mixture of polylactic acid, an aliphatic polyester of an aliphatic diol and an aliphatic dicarboxylic acid may be used. In particular, a mixture of polylactic acid and the homo- or copolyhydroxycaproic acid, or a mixture of polylactic acid and the homo- or copolybutylene succinate may be used.

Examples of the aliphatic polyhydroxycarboxylic acid used in the present invention include a copolymer of one or more lactic acids and one or more hydroxycarboxylic acids other than lactic acid. In this case, the lactic acid may be L-lactic acid, D-lactic acid and / or a mixture thereof. Hydroxycarboxylic acids other than lactic acid are compounds having at least one hydroxyl group and one carboxyl group in the molecule, for example,
Glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 4-hydroxyvaleric acid, 5-hydroxyvaleric acid, 6
-Hydroxycaproic acid and the like, or a mixture of a combination of two or more thereof.

The polylactic acid used in the present invention is polylactic acid,
Alternatively, random copolymers and block copolymers obtained by dehydration condensation of lactic acid with the above-mentioned hydroxycarboxylic acid and / or aliphatic dicarboxylic acid and aliphatic diol, or polylactic acid and aliphatic polyhydroxycarboxylic acid and / or aliphatic It may be a mixture with polyester.

The polylactic acid, the polyhydroxycarboxylic acid and the aliphatic polyester have different physical properties depending on the mixing ratio and the molecular weight at the time of mixing. However, the mixing ratio and the molecular weight are not limited in the present invention. A polymer composition exhibiting physical properties suitable for the intended use can be appropriately selected.

[Method for Producing Polylactic Acid] The method for producing polylactic acid used in the present invention is not particularly limited. Specific examples of the method for producing polylactic acid include, for example, a method referring to the method disclosed in JP-A-6-65360. That is, it is a direct dehydration condensation method in which lactic acid and / or a hydroxycarboxylic acid other than lactic acid, or an aliphatic diol and an aliphatic dicarboxylic acid are directly dehydrated and condensed in the presence of an organic solvent and a catalyst.

[Aliphatic hydroxycarboxylic acid] Specific examples of the aliphatic hydroxycarboxylic acid other than lactic acid constituting the aliphatic polyester used in the present invention include, for example, glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 4-hydroxyvaleric acid, 5-hydroxyvaleric acid, 6-hydroxycaproic acid and the like.

[Aliphatic polycarboxylic acid and its anhydride]
The aliphatic polyester comprising an aliphatic polyhydric alcohol and an aliphatic polycarboxylic acid used in the present invention may be one or more aliphatic polycarboxylic acids (preferably, aliphatic dicarboxylic acids) and / or And one or more aliphatic polyhydric alcohols (preferably aliphatic diols) by dehydration polycondensation. Specific examples of the aliphatic polycarboxylic acid and its anhydride in this case include, for example, oxalic acid, succinic acid, malonic acid, glutaric acid, adipic acid,
Pimelic acid, suberic acid, azelaic acid, sebacic acid,
Aliphatic dicarboxylic acids such as undecandioic acid, dodecandioic acid, fumaric acid and maleic acid, phenylsuccinic acid, 1,4-
Examples include phenylenediacetic acid and the like and anhydrides thereof.

[Aliphatic polyhydric alcohol] Specific examples of the aliphatic polyhydric alcohol include, for example, ethylene glycol, diethylene glycol, triethylene glycol,
Propylene glycol, dipropylene glycol, 1,
3-butanediol, 1,4-butanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol, neopentyl glycol, tetramethylene glycol, 1,4-cyclohexane Examples include dimethanol, polyethylene glycol, polytetramethylene glycol, and 1,4-benzenedimethanol.

[Biodegradable Plastic] The term "biodegradable plastic" used in the specification of the present application is a plastic that is decomposed in nature by microorganisms into low molecular weight compounds. Specific examples of biodegradable plastics include polyhydroxybutyrate, polyhydroxyvalerate, those synthesized by microorganisms such as cellulose, polylactic acid, those produced by chemical synthesis such as polycaprolactone, starch, polyvinyl alcohol. There are natural products such as those added. The decomposition method is such that a high molecular chain of the material is hydrolyzed by an extracellular degrading enzyme secreted by microorganisms attached to the surface of the plastic material to generate a low molecular weight compound. Next, the decomposition products are taken into the microorganisms, and are used for synthesizing various biological substances and for energy production through various metabolic pathways. The biodegradability can be evaluated by, for example, an embedding test in soil or compost, a decomposition test using a cultured microorganism, a decomposition test using an enzyme preparation, and the like. More specifically, for example, ASTM D5209
-91 (biodegradability test) and ASTM D5338-92
(Soil regression performance test) can also be evaluated.

[Aliphatic] The term "aliphatic" used in the specification of the present application includes not only aliphatic in a narrow sense but also alicyclic having a substantially low aromaticity. The term "aliphatic" as used in the specification of the present application includes a group consisting of substantially low aromatic compounds having a divalent hydrocarbon group containing at least one carbon atom in a molecule. Specifically, not only an aliphatic group in a narrow sense, but also an alicyclic group having a substantially low aromaticity, a group obtained by combining them, or a group formed by a hydroxyl group, nitrogen, sulfur, silicon, phosphorus, or the like It also includes the group consisting of compounds having a divalent residue to be bonded in the molecule, and more specifically, those described above include, for example, a hydroxyl group, an alkyl group, a cyclalkyl group,
An allyl group, an alkoxy group, a cycloalkoxy group, an allyloxy group, and a group consisting of compounds having a group substituted by a halogen group in the molecule are also included. By appropriately selecting these substituents, various properties (heat resistance, toughness, biodegradability, strength, etc.) of the copolymer according to the present invention can be controlled. The term "aliphatic" compound used in the specification of the present application includes not only one compound but also a combination of two or more compounds.

[Powder] The term "powder" used in the specification of the present application includes an aggregate of particles.

[Particles] The term "particles" used in the specification of the present application completely includes, but is not necessarily equivalent to, the concepts that these words generally have in polymer chemistry. As for the scanning electron microscopic form of the “particle” used in the specification of the present application, for example, a form having many protrusions in the form of raspberry or gold rice sugar (confinito in Portuguese), flattened erythrocyte Rugby ball-like spheroid-like form, Escherichia coli-like spindle-like form, hollow particle form having one or more voids (voids) inside, and hollow particles like bells Further, the present invention also includes an embodiment having one or more non-hollow particles, an embodiment having one or more hollow particles inside the hollow particles such as Russian folk art matryoshka, and the like. The term “particles” as used in the specification of the present application also includes, for example, polymer emulsions, latex, and microspheres constituting a polymer suspension.

[Mixing of Aliphatic Polyester and Microwax] In the present invention, specific examples of the method of mixing the aliphatic polyester and microwax include a roll machine, a kneader, a mixer (Banbury type, transfer type, etc.), a calender. A method in which kneading machines such as equipment and an extruder are appropriately combined, and the conditions of each step (temperature, melting or non-melting, rotation speed, vacuum, atmosphere under an inert gas, etc.) are appropriately set, and sufficiently uniform mixing is performed. Alternatively, a method in which both are dissolved or dispersed in an organic solvent at normal temperature or under heating can be adopted, but the method is not limited thereto.

[Additives] The coating material used in the present invention suitably includes a synthetic resin composition including epoxy resin, polyester resin, polyamide resin, etc., cellulose or cellulose derivative, etc., according to the purpose. A natural resin or semi-synthetic resin composition may be blended to form a composition. In the coating material used in the present invention, a pigment, a dye, a colorant, a filler, a non-biodegradable polymer, a flow regulator, a thixotropic agent (thixotropy-imparting agent), a surface modifier, and a gloss imparting agent are appropriately used according to the purpose. Additives such as an agent, an anti-blocking agent, a plasticizer, a charge control agent, an ultraviolet absorber, an anti-penetrating agent, an antioxidant, a stabilizer, a leveling agent, and a surfactant can also be added.

[Anti-blocking agent] An anti-blocking agent can be appropriately added to the coating material used in the present invention according to the purpose. Specific examples of the antiblocking agent include, for example, acetamide, propionic amide, stearic amide, aliphatic amides such as cerotic amide, diacetamide, bisoleic amide, bislauric amide, methylene bisstearamide, ethylene Bis fatty acid amides such as bis stearoamide, higher fatty acid esters such as myryl xylate, butylene glycol dimontanate, glycerin tri-1,2 hydroxystearate, molecular weight 1,000
Examples thereof include, but are not limited to, polyethylene, atactic polypropylene, and partially oxidized polyolefins thereof. The amount of antiblocking agent in the composition is usually 10%
The following is preferred.

[Surface Conditioning Agent] A surface conditioning agent can be appropriately added to the coating material used in the present invention according to the purpose. As specific examples of the surface conditioner, for example,
Acrylic ester-based monomers, or homo- or copolymerized oligomers of styrene-based monomers, metal salts of perfluorocarboxylic acid or perfluorosulfonic acid, esters of polyethylene glycol or propylene glycol with perfluorocarboxylic acid, and the like. It is possible, but not limited to these. Usually, the amount of the surface conditioner in the composition is preferably 5% or less.

[Pigment] In the present invention, a pigment can be appropriately added according to the purpose in order to impart an appropriate color tone to the coating material. Specific examples of pigments include, for example,
Examples thereof include inorganic pigments such as titanium oxide, iron oxide, chromium oxide, and carbon black, and organic pigments such as phthalocyanine blue, phthalocyanine green, and synchasia red, but are not limited thereto.

[Filler] In the present invention, a filler can be appropriately added to the coating material according to the purpose. Specific examples of the filler include minerals such as kaolin, silica sand, clay, diatomaceous earth, talc and bentonite, and inorganic salts such as calcium carbonate.

[Plasticizer] In the present invention, a plasticizer can be appropriately added according to the purpose. Specific examples of the plasticizer include, for example, adipic acid ester, phosphoric acid ester, phthalic acid ester, sebacic acid ester, polyester obtained from adipic acid or azelaic acid, and epoxidized plasticizer. Not something.

[Blending Method] In the present invention, specific examples of the method of blending the coating material composition containing the aliphatic polyester and the microwax include a roll machine, a kneader, a mixer (Banbury type, transfer type, etc.), A kneader such as a calender and an extruder are appropriately combined, and the conditions of each step (temperature, melting or non-melting, rotation speed, vacuum, atmosphere under an inert gas, etc.) are appropriately set, and the mixture is sufficiently uniformly mixed. After that, a method of obtaining a powder composition by a pulverizer or the like, or a method of mixing and dissolving or dispersing in a solution or dispersion of an aliphatic polyester and a microwax can be employed, but is not limited thereto.

[Blending and Kneading] In the present invention, one embodiment of the blending and kneading step of adding an additive or the like to the coating material is as follows.
Additives such as a plasticizer, a charge control agent, a pigment, a filler, and an extender, and melt and knead sufficiently in a range of 50 to 180 ° C.
After cooling, it is pulverized to an appropriate particle size and manufactured. As the melt-kneading apparatus, a heating roll, a heating kneader, an extruder or the like is usually used.

[Composition of Coating Material] In the present invention, the coating material contains an aliphatic polyester and a microwax. Two or more aliphatic polyesters and microwaxes may be used in combination. The content of the aliphatic polyester in the coating material is 20 to 90% by weight, preferably 30 to 70% by weight. If the amount is less than 20% by weight, the strength of the film is reduced, and a good film cannot be obtained, so that the elution of the fertilizer component cannot be suppressed. On the other hand, if it exceeds 90% by weight, the water vapor permeability is too high, which is not preferable.
The content of the microwax in the coating material is 10 to 80% by weight, preferably 30 to 70% by weight. 10% by weight
If it is less than 90%, the water vapor permeability is too high, and if it is more than 90%, the strength of the coating is reduced, and the elution of the fertilizer component cannot be suppressed because a good coating cannot be obtained.

[Coating of Fertilizer] In the present invention, the coating of the coating agent on the fertilizer can be performed by a known method, and is roughly classified into a method using a solvent (solvent method) and a method not using a solvent (solventless method). it can. In the solvent method, a material obtained by dissolving or dispersing a coating material in a solvent is sprayed and dried by heating, or a fertilizer is immersed in a coating material solution or dispersion, and then the solvent is removed and dried. Drying by a heated air stream is efficient.

The solvent used for the coating solution or dispersion varies depending on the composition of the individual aliphatic polyester and the coating material.
-Dichloroethane, tetrachloroethylene, trichloroethylene, 1,1,1-trichloroethane, 1,1,2
Chlorinated aliphatic solvents represented by trichloroethane,
Chlorinated aromatic solvents represented by ο-dichlorobenzene, 1,2,4-trichlorobenzene, dioxane, 1-
Acetoxy-2-ethoxyethane, 1-acetoxy-2
-Methoxyethane, glycol ethers represented by ethylene glycol dimethyl ether, N-methylpyrrolidone, amide solvents represented by N, N-dimethylacetamide, N, N-dimethylformamide, and fragrances represented by benzene and toluene A group solvent or the like can be used.

The drying temperature is determined in consideration of the solubility, the evaporation rate and the boiling point of the solvent, and is usually 20 to 120 ° C., preferably 30 to 100 ° C.

As the solventless method, in addition to the method of using a coating material melt or dispersion in place of the coating material solution or dispersion in the solvent method, for example, a method described in JP-A-9-25189 is used. A method in which a powdery coating material is adhered to fertilizer particles by a method and then heated and melted for coating, or Japanese Patent Application No. Hei 8-2
According to the plastic spraying method described in 23401, a powdery coating material is sprayed onto a fertilizer together with a non-combustion gas and a flame, and the coating material powder is melted or softened by heating with a flame to be fused to the fertilizer surface. A coating method can be adopted.

The coating is preferably carried out while mixing fertilizer particles in order to obtain a uniform coating and to prevent adhesion of the particles. As a method of mixing the fertilizer particles, for example, a method using a rolling device such as a rotary drum type rolling device, an inclined rotary pan type rolling device, a fluidized bed, a spouted fluidized bed, a fluidized bed such as a rolling fluidized bed, etc. No. Fertilizer coating is usually
Such a mixing apparatus is equipped with a one-fluid or two-fluid nozzle or a spray gun.

[Powder-like coating material] In the present invention, as a specific example of a method of obtaining a powdery coating material, a method of mixing an aliphatic polyester powder and a microwax powder,
Alternatively, a method of pulverizing the mixture obtained by the above mixing method, a method of cooling and crystallizing both solutions or dispersions to precipitate a powder, and a method of spraying both solutions or dispersions from a nozzle to remove a solvent. A method (spray drying method), a method in which both solutions or dispersions are mixed with a poor solvent under stirring or without stirring to precipitate a powder, and the solvent is distilled off. Both solutions or dispersions are freeze-dried. The method of grinding after making into a porous lyophilized shape, the method of stirring and grinding with glass beads, the method of grinding with a stone mill, the method of finely cutting fine filaments, etc., are mentioned, and the particle diameter of the coating material is 500μ or less. The grinding method is not particularly limited as long as it can be ground into particles. If the particle size is larger than 500 μm, it is difficult to obtain a uniform coating.

[Elution of fertilizer] The elution of fertilizer components of the coated fertilizer produced in the present invention can be examined by a fertilizer elution test in water. This method is effective not only for simulating fertilizer elution in paddy fields and hydroponics, but also for predicting fertilizer release in field soil.

[Biodegradability of the Coating] The biodegradability of the coating can be examined by a long-term burial test in soil or an accelerated test in compost of the coated fertilizer.

[0058]

The present invention will be specifically described below with reference to examples and comparative examples.

[Dissolution rate] The dissolution rate of the fertilizer component of the coated fertilizer was measured by the following method. 12.5 g of sample is 30
A 0 ml Erlenmeyer flask is precisely weighed and distilled water of 30 ° C.
After adding ml, the mixture was allowed to stand at 30 ° C. for a predetermined time. The solid was filtered off and the total amount of nitrogen in the filtrate was analyzed to determine the amount A of eluted nitrogen. Further, 12.5 g of the coated fertilizer was pulverized with a pulverizer, and the fertilizer component was stirred and dissolved in 250 ml of distilled water, and solid matter was separated by filtration.
I asked. According to the following equation (1)

[Formula 1] The elution rate = [A / B] × 100 (%) was determined.

[Coating rate] 12.5 g of the coated fertilizer was pulverized with a pulverizer and dissolved in 250 ml of distilled water with stirring. The solid matter was separated by filtration, washed with water, and the weight (Cg) of the membrane shell after drying was measured.

[Formula 2] The coverage = [C / (12.5−C)] × 100 (%) was determined.

[Weight average molecular weight] The weight average molecular weight of aliphatic polyesters was determined by gel permeation chromatography (GPC) using chloroform as a solvent at 40 ° C.
Using a column for GPC kept warm in the above, it was calculated from the calibration curve of the molecular weight of polystyrene standard sample and the retention time.

[Biodegradability] In the biodegradability test, 12.5 g of the coated fertilizer was buried in compost at room temperature for 30 days.
The fertilizer particles were selected, crushed, washed with water, filtered to remove insolubles, dried, and the weight (Dg) of the remaining membrane shell was measured, and the residual ratio of the coating material was determined by the following equation (3).

[Formula 3] Residual rate of coating material = [D / C] × 100 (%)

[Coating Strength] The coating strength of the coated fertilizer was determined by placing 100 g of a sample in a cylindrical container having a length of 5 m and rotating the cylinder 10 times with the middle portion of the cylinder as a fulcrum. , And evaluated by the change in the dissolution rate of the fertilizer before and after the test.

[Example 1] 5 kg of large urea (manufactured by Mitsui Chemicals, Inc.) was charged into a spouted fluidized bed apparatus as shown in FIG. While blowing air, urea was jet-mixed, and poly-L-lactic acid (weight average molecular weight: 150,000) 350
g and 155 micro wax (Nippon Oil Co., Ltd.)
A coating solution was prepared by spraying a solution of 150 g in 4500 g of trichloroethylene at 80 ° C. to obtain 5500 g of coated urea. The coating rate obtained by pulverization was 10%, the time required for the dissolution rate to reach 80% was 100 days, and the film remaining rate in the compost was 3%. The dissolution rate of the sample after the coating strength test is 8
The time to reach 0% was 100 days.

Example 2 In Example 1, poly-L-lactic acid 35 was used.
0 g and 155 micro wax 150 g instead of poly L-lactic acid 250 g and 155 micro wax 250
coating was performed under the same conditions as in Example 1 except that g was used,
5500 g of coated urea was obtained. The coverage rate obtained by grinding is 1
The time required for the dissolution rate to reach 80% was 180 days, and the residual film rate in the compost was 2%. The time required for the dissolution rate of the sample to reach 80% after the coating strength test was 170 days.

Example 3 Poly L-lactic acid 35 in Example 1 was used.
0 g and 150 g of 155 microwax instead of 150 g of poly L-lactic acid and 155 microwax 350
coating was performed under the same conditions as in Example 1 except that g was used,
5500 g of coated urea was obtained. The coverage rate obtained by grinding is 1
The time required for the dissolution rate to reach 80% was 270 days, and the residual film rate in the compost was 1%. The time required for the dissolution rate of the sample to reach 80% after the coating strength test was 220 days.

Example 4 A spouted fluidized bed apparatus as shown in FIG. 1 was charged with 5 kg of composite phosphorus fertilizer 444 containing round swallow urea (manufactured by Mitsui Toatsu Fertilizer Co., Ltd.) as a composite chemical fertilizer. While blowing air for jet flow at 50 ° C. from the lower part, the compound fertilizer is jet-mixed, and polycaprolactone (weight average molecular weight: 50,000) 3 is supplied from a two-fluid nozzle installed at the lower part.
A solution obtained by dissolving 50 g and 150 g of 180 micro wax (manufactured by Nippon Oil Co., Ltd.) in 4500 g of 1,1,2-trichloroethane at 50 ° C. was spray-coated to obtain 5500 g of a coated fertilizer. 10% coverage after grinding
The time required for the dissolution rate to reach 80% is 120 days,
The residual film ratio in the compost was 2%. The time required for the dissolution rate of the sample to reach 80% after the coating strength test was 100 days.

Example 5 A main part of a spout fluidized bed apparatus as shown in FIG. 1 was charged with 5 kg of large urea (manufactured by Mitsui Chemicals, Inc.). While blowing, urea is jet-mixed, and polybutylene succinate (weight average molecular weight 1
A solution prepared by dissolving 350 g of (30,000) and 150 g of 155 microwax (produced by Nippon Oil Co., Ltd.) in 4500 g of 1,2-dichloroethane at 80 ° C. was sprayed to obtain 5500 g of coated urea. The coverage rate obtained by grinding is 1
The time required for the dissolution rate to reach 80% was 150 days, and the residual film rate in the compost was 3%. The time required for the dissolution rate of the sample to reach 80% after the coating strength test was 140 days.

[Comparative Example 1] In Example 1, poly-L-lactic acid 35 was used.
Coating was performed under the same conditions as in Example 1 except that 500 g of poly-L-lactic acid was used instead of 0 g and 150 g of 155 microwax to obtain 5500 g of coated urea. The coating rate obtained by pulverization was 10%, the time required for the dissolution rate to reach 80% was 20 days, and the film remaining rate in the compost was 5%. The time required for the dissolution rate of the sample to reach 80% after the coating strength test was 20 days.

Comparative Example 2 Coating was carried out under the same conditions as in Example 1 except that 150 g of 155 paraffin wax (manufactured by Nippon Seiro Co., Ltd.) was used instead of 150 g of 155 microwax, and 5500 g of coated urea. I got The coverage obtained by pulverization was 10%, and the elution rate was 8%.
The time to reach 0% was 35 days, and the residual film ratio in the compost was 1%. The dissolution rate of the sample after the coating strength test is 8
The time to reach 0% was 30 days.

Comparative Example 3 Poly L-lactic acid 35 in Example 1
0 g and 150 g of 155 microwax instead of 100 g of poly-L-lactic acid and 155 paraffin wax 40
Coating was performed under the same conditions as in Example 1 except that 0 g was used to obtain 5500 g of coated urea. The coating rate obtained by pulverization was 10%, the time required for the dissolution rate to reach 80% was 80 days, and the coating remaining rate in the compost was 1%. The time required for the dissolution rate of the sample to reach 80% after the coating strength test was 25 days.

[Comparative Example 4] Coating was performed under the same conditions as in Example 1 except that 150 g of High Wax 420P (polyethylene wax manufactured by Mitsui Chemicals) was used instead of 150 g of 155 microwax.
g was obtained. The coating rate obtained by pulverization was 10%, the time required for the dissolution rate to reach 80% was 40 days, and the film remaining rate in the compost was 20%. The time required for the dissolution rate of the sample to reach 80% after the coating strength test was 35 days.

Comparative Example 5 Poly-L-lactic acid 35 in Example 1
0 g and 150 g of 155 microwax instead of 100 g of poly L-lactic acid and 400 g of high wax 420P
Coating was carried out under the same conditions as in Example 1 except that urea was used to obtain 5500 g of coated urea. The coverage obtained by grinding is 10
%, The time required for the dissolution rate to reach 80% was 90 days, and the residual film rate in the compost was 30%. The time required for the dissolution rate of the sample to reach 80% after the coating strength test was 50 days.

[0074]

Industrial Applicability According to the present invention, a coated fertilizer coated with a coating material containing an aliphatic polyester resin and microwax has a wide range of elution control of fertilizer components and excellent coating strength.
In addition, since the coating material has a function of biodegrading in soil after the elution is completed, there is no problem that the film shell accumulates.

[Brief description of the drawings]

FIG. 1 is a schematic view illustrating a main part of a spouted fluidized bed apparatus used for producing a coated fertilizer in an example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Spout fluidized bed apparatus 2 ... Two-fluid nozzle 3 ... Dispersion plate 4 ... Coating material solution or dispersion liquid 5 ... Compressed air 6 ... Cylinder 7 ... Fluid air

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takayoshi Kaizuka 1900 Togo, Togo, Mobara-shi, Chiba

Claims (7)

[Claims] 1. An aliphatic polyester of at least 20% by weight and at least 90% by weight.
Weight% or less, and micro wax 10 weight% or more 8
A coated fertilizer having a coating layer containing 0% by weight or less. 2. The coated fertilizer according to claim 1, wherein the aliphatic polyester is polycaprolactone. 3. The coated fertilizer according to claim 1, wherein the aliphatic polyester is lactic acid and / or a copolymer of lactic acid and another hydroxycarboxylic acid other than lactic acid. 4. The coated fertilizer according to claim 1, wherein the aliphatic polyester is a polyester of lactic acid and / or an aliphatic polyhydric alcohol and an aliphatic polycarboxylic acid. 5. The coated fertilizer according to claim 1, wherein the aliphatic polyester is a polyester of an aliphatic polyhydric alcohol and an aliphatic polycarboxylic acid. 6. The coated fertilizer according to claim 4, wherein the aliphatic polyhydric alcohol is ethylene glycol and / or 1,4-butanediol. 7. The method according to claim 1, wherein the aliphatic polycarboxylic acid is succinic acid and / or succinic acid.
The coated fertilizer according to claim 4 or 5, which is adipic acid.