JPH09263476A - Decomposable coated granular fertilizer and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a coated fertilizer large in the width of elution control, excellent in stability at the time of storing and inducing the decomposition of coating material in the environment after the elution is completed by coating with the coating material containing an aliphatic polyester and a polyolefin wax. SOLUTION: The coating material is prepared by containing 5-80wt.% aliphatic polyester consisting of an aliphatic polyester or polyhydroxy carboxylic acid expressed by a formula ((n) expresses the polymerization degree necessary to have the number average molecular weight of 1000-1000000, R<1> expresses a 2-20C aliphatic hydrocarbon group and R<2> expresses a 0-24C aliphatic hydrocarbon group) and 20-95wt.% low density polyethylene wax preferably 0.860-0.940g/cm<3> in the density and having the number average molecular weight of 300-10000. The coated granular fertilizer is obtained by spraying a solution prepared by dissolving or dispersing the coating material in a solvent to the granular fertilizer and drying in a hot air stream.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a coated fertilizer using a novel coating material and a method for producing the same. More specifically, the present invention relates to a coated fertilizer having a wide range of elution control of fertilizer components, excellent stability during storage, and causing decomposition of the coating material in the environment after completion of elution, and a method for producing the same.

[0002]

2. Description of the Related Art A coated fertilizer capable of controlling elution of fertilizer by encapsulating the entire periphery of a granular fertilizer with a resin or the like has made remarkable progress in recent years as a typical slow-release fertilizer. That is, it is possible to prevent excessive fertilization, improve the utilization efficiency of fertilizer components in crops, reduce the loss of fertilizer components into rivers, and reduce labor by reducing the number of fertilizer applications. It is a well-known fact that it has achieved sufficient results in terms of efficiency, efficiency, and environmental protection.

As a coating technique for granular fertilizers, for example, coating with an olefinic resin described in JP-B-54-3104, JP-B-60-37074, JP-B-60-21952, and JP-B-60- 3040 publication,
A coating composed of an olefin resin and an inorganic filler described in JP-B-60-102, or JP-B-60-29.
There is known a floating prevention method, etc., in which the surface of the coated fertilizer described in Japanese Patent No. 679 is fused with fine powder. However, these coating materials are extremely stable substances in the natural world, and after the elution of the fertilizer components, there is a new problem that they remain in the fields as shells of the coated fertilizer.

As a technique for dealing with the problem of remaining shells of the above-mentioned coated fertilizer, (1) a photodegradable coating with an ethylene-carbon monoxide polymer described in JP-A-6-56568,
(2) Photodegradable coating comprising an olefin resin and a metal complex described in JP-A-5-201786, (3) biodegradable coating with polylactic acid described in JP-A-7-33577, or (4 ) Japanese Patent Publication No. 2-23517,
JP-A-4-89384, JP-A-5-85873, JP-A-7-33576, and JP-B-7-505.
Inventions and the like relating to coating using the biodegradable resin composition described in Japanese Patent Application Publication No. JP-A No. 2003-242242 are disclosed. However, the inventions relating to these degradable coatings show that they do not show disintegration depending on the conditions such as burial in the soil, or show disintegration but have too high water permeability, and therefore elute over several months or more. It was not sufficient because there was a problem that it could not be applied to the long-term dissolution type fertilizer that controls the effluent.

For example, (1) a photodegradable coating with an ethylene-carbon monoxide polymer described in JP-A-6-56568, and (2) a metal on an olefin resin described in JP-A-5-201786. The photodegradable coating containing the complex does not decompose unless it is irradiated with light, especially ultraviolet rays, and the coating remaining in the soil is hardly decomposed. Further, (3) the biodegradable coating described in JP-A-7-33577 cannot be applied to the long-term dissolution control type because it has extremely high water permeability and biodegradability. Furthermore, (4) Special Fairness 2
No. 23517, Japanese Patent Application Laid-Open No. 4-89384, Japanese Patent Application Laid-Open No. 5-85873, Japanese Patent Application Laid-Open No. 7-33576, Japanese Patent Publication No. 7-505, the coating using the biodegradable resin composition is However, even if the amount of biodegradable resin is not increased, sufficient disintegration performance cannot be exhibited, but if the amount of biodegradable resin is increased, the moisture permeability of water becomes high and it cannot be applied to long-term control type coated fertilizer. Further, the fertilizer disclosed in Japanese Patent Laid-Open No. 7-33576, which has a multilayer coating structure, is not good in industrial efficiency. Further, none of the above-mentioned conventional coated granular fertilizers can achieve both degradability in the environment and stability during product storage.

[0006]

DISCLOSURE OF THE INVENTION The present invention provides a coated fertilizer having a wide elution control range of fertilizer components, excellent stability during storage, and causing decomposition of the coating material in the environment after completion of elution, and its production. The challenge is to provide a method.

[0007]

As a result of intensive studies, the present inventors have found that the above problems can be solved by using a coated fertilizer composed of an aliphatic polyester and a polyolefin wax as a coating material, and have arrived at the present invention. . That is, the present invention is the following (1) to (14). (1) A coated granular fertilizer having a coating layer containing 5% by weight or more and 80% by weight or less of an aliphatic polyester and 20% by weight or more and 95% by weight or less of a polyolefin wax. (2) The coated granular fertilizer according to (1) above, wherein the aliphatic polyester is an aliphatic polyester represented by the general formula (I).

[0008]

Embedded image

(N represents the degree of polymerization required for the number average molecular weight Mn to be 1,000 or more and 1,000,000 or less. R ¹ is an aliphatic hydrocarbon group having 2 or more and 20 or less carbon atoms,
R ² is an aliphatic hydrocarbon group containing 0 or less and having 24 or less carbon atoms. R ¹ and R ² may each include two or more types). (3) n of the aliphatic polyester is 1,000,0 when the number average molecular weight Mn of the polyester is larger than 15,000.
The coated granular fertilizer according to the above (2), which has a degree of polymerization required to be 00 or less.

(4) The coated granular fertilizer according to (1) above, wherein the aliphatic polyester is polyhydroxycarboxylic acid. (5) The above (1), wherein the aliphatic polyester is polylactic acid
Coated granular fertilizer. (6) The coated granular fertilizer according to (1) above, wherein the aliphatic polyester is polycaprolactone. (7) The coated granular fertilizer according to (1) above, wherein the polyolefin wax is polyethylene wax.

(8) The polyolefin wax has a density of 0.
860 g / cm ³ or more 0.940 g / cm ³ or less of coated granular fertilizer of the (1) is a low density polyethylene waxes. (9) The number average molecular weight of the polyolefin wax is 300
The coated granular fertilizer according to (1) above, which is 10,000 or more. (10) The number average molecular weight of the polyolefin wax is 57
The coated granular fertilizer according to (1) above, which is 0 or more and 10,000 or less. (11) The number average molecular weight of the polyolefin wax is 1,
000 or more and 10,000 or less, the coated granular fertilizer according to (1) above. (12) The coated granular fertilizer according to (1), further including 0.01 to 75% by weight of an aliphatic polymer and / or a surfactant as a moisture permeability adjusting agent in the coating layer.

(13) The coated granular fertilizer according to (1) above, which has a coating layer containing a mixture of an aliphatic polyester and a polyolefin wax. (14) A liquid prepared by dissolving or dispersing the coating material in a solvent is
The method for producing a coated granular fertilizer according to the above (1), characterized in that the granular fertilizer is sprayed and dried by a heated air stream. Hereinafter, the present invention will be described in more detail.

The aliphatic polyester used in the coating layer of the coated granular fertilizer of the present invention has a structure in which polyhydric alcohol and polycarboxylic acid are polycondensed and a structure in which hydroxycarboxylic acid is polycondensed. An aliphatic polyester having a structure in which a polyhydric alcohol and a polycarboxylic acid are polycondensed is preferable because an aliphatic polyester having a structure in which the elution of fertilizer can be easily suppressed can be easily synthesized. A preferred example of the aliphatic polyester having a structure in which a polyhydric alcohol and a polycarboxylic acid are polycondensed is represented by the general formula (I).

[0014]

Embedded image (N is a number average molecular weight Mn of 1,000 or more and 1,000
It represents the degree of polymerization required to reach 50,000 or less. R ¹ is an aliphatic hydrocarbon group having 2 to 20 carbon atoms, and R ² is an aliphatic hydrocarbon group containing 0 and having 24 carbon atoms or less. R ¹ ,
R ² may each include two or more types).

The n of the general formula (I) of the present invention is better from the viewpoint of strength, but since the viscosity of the coating material when coating the granular fertilizer with the coating material is high, it is represented by the general formula (I). The aliphatic polyester used has a number average molecular weight Mn of 1,000.
The degree of polymerization required to be 1,000,000 or more is good, more preferably 15,000 or more and 1,000,000 or less, and more than 25,000 and 1.00.
It is more preferable that the amount is 2,000 or less. Also, if the aliphatic polyester contains a large amount of low-molecular components, the strength after molding decreases, so the content of components with a molecular weight of 500 or less is 10% by weight.
Or less, preferably 1% by weight or less, more preferably 0.1% by weight or less.
% By weight or less. The ratio Mw / Mn of the weight average molecular weight Mw and the number average molecular weight Mn is preferably 1 or more and 20 or less.

R ¹ is an aliphatic hydrocarbon group having 2 to 20 carbon atoms and R ² is an aliphatic hydrocarbon group containing 0 and having 24 carbon atoms or less. These may contain an unsaturated bond, may contain an alicyclic structure, and may each contain two or more kinds. The aliphatic polyester of the general formula (I) of the present invention is produced by polycondensation of an aliphatic hydrocarbon diol (hereinafter simply referred to as diol) and an aliphatic hydrocarbon dicarboxylic acid (hereinafter simply referred to as dicarboxylic acid). To be done.

The dicarboxylic acid is selected from dicarboxylic acid itself, dicarboxylic acid ester and dicarboxylic acid anhydride. The diol and dicarboxylic acid (or ester or acid anhydride thereof) used in the production of the aliphatic polyester used in the present invention are such that the diol is an aliphatic hydrocarbon group having 2 to 20 carbon atoms except the hydroxyl group. And the dicarboxylic acid (or its ester or acid anhydride) is an aliphatic hydrocarbon group having 24 or less carbon atoms, and the remainder excluding the carbonyl group (or its ester or acid anhydride) contains 0. (These may contain an unsaturated bond or an alicyclic structure. Also, two or more kinds may be used for each.).

Examples of the diol include ethylene glycol, propylene glycol, trimethylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1, 7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-
Dodecanediol, 1,13-tridecanediol,
1,14-tetradecanediol, 1,16-hexadecanediol, 1,18-octadecanediol, 1,
20-eicosanediol, neopentyl glycol,
1,4-cyclohexanedimethanol, 3-butene-
1,2-diol, 2-butene-1,4-diol,
2,5-dimethyl-3-hexene-2,5-diol,
1,5-hexadiene-3,4-diol, 2,6-octadiene-4,3-diol, and the like, and examples of the dicarboxylic acid (or its ester or acid anhydride) include oxalic acid, malonic acid, and Succinic acid, glutaric acid,
Adipic acid, pimelic acid, suberic acid, azelaic acid,
Sebacic acid, undecane diacid, dodecane diacid, tridecane diacid, tetradecane diacid, pentadecane diacid, hexadecane diacid, octadecane diacid, eicosane diacid, heneicosan diacid, docosane diacid, tetracosane diacid, dimethyl succinate. , Dimethyl glutarate, dimethyl adipate, dimethyl azelate, diethyl sebacate, dimethyl dodecane diate, diethyl tetradecane diate, dimethyl eicosane diate, succinic anhydride, glutaric anhydride,
Maleic acid, fumaric acid, dimethyl maleate, dimethyl fumarate, and octasocanylic succinic anhydride which is a substituted succinic acid (or its ester or acid anhydride),
Examples thereof include docosaeicosenylsuccinic anhydride.

The above-mentioned diol and dicarboxylic acid (or ester or acid anhydride thereof) have crystallinity, melting point,
It is also possible to use two or more kinds for controlling the molding processability. In addition, these raw material diols and dicarboxylic acids (or their esters or acid anhydrides) may contain trifunctional or higher functional groups as impurities. Moreover, you may positively add trifunctional or more than trifunctional polyhydric alcohol and polyhydric carboxylic acid. The amount of the trifunctional or higher polyhydric alcohol and the polycarboxylic acid is preferably such that the produced polymer is substantially solvent-soluble. Substantially solvent-soluble means that 95 parts of the solvent are added to 5 parts by weight of the produced polymer.
It means that 80% by weight or more of the charged polymer is recovered in the filtrate obtained by filtering the solution added by weight with a G2 glass filter at a differential pressure of 1 Kg / cm ² .

Specific examples of the aliphatic polyester represented by the above general formula (I) of the present invention include polyethylene succinate, polyethylene adipate, polyethylene tetradecanedioate, polytetramethylene succinate,
Polytetramethylene adipate, polytetramethylene dodecanedioate, polytetramethylene eicosandioate, polyhexamethylene glutamate, polyhexamethylene adipate, polydecamethylene succinate,
Polydecamethylene dodecanedioate, polydodecamethylene succinate, polydodecamethylene eicosandioate, polydodecamethylene tetradecanedioate,
Examples thereof include polyhexadecamethylene succinate and polyhexadecamethylene eicosandioate.

Of these, aliphatic polyesters using a polyhydric alcohol or a polycarboxylic acid having a small number of carbon atoms are preferred because the raw materials are easily synthesized and easily available. Specific examples thereof include polyethylene succinate, polyethylene adipate, polytetramethylene succinate, polytetramethylene adipate, polyhexamethylene glutamate, and polyhexamethylene adipate. In the present invention, the raw material diol and dicarboxylic acid (or its ester or acid anhydride)
Therefore, one of the molar ratios of the charged amounts becomes excessive, preferably 0.5 or more and 2.0 or less, more preferably 0.8 or more and 1.2 or less, and still more preferably 0.9 or more and 1.1 or less. By doing so, it is possible to produce an aliphatic polyester having a high molecular weight and a functional group of a component used in excess at the end (a structure containing both may be used depending on the charging ratio).

As a method for producing the aliphatic polyester used in the present invention, it is important to make the evaporation surface area larger than the charged amount by forming a thin film, and the volume of the reaction system is V (cm ³ ). When the surface area is A (cm ² ), it is necessary to manufacture A / V at least 1. It is preferably 4 or more, more preferably 6 or more. The larger the A / V, the more preferable for the production of the high molecular weight aliphatic polyester, but from the viewpoint of economy, the production is performed at 500 or less, preferably 50 or less. When the A / V changes during the production, it suffices that the A / V becomes 1 or more when the molecular weight becomes the highest, that is, usually when the polymerization is completed. Further, the lower the pressure during production, the higher the molecular weight of the aliphatic polyester, but there is a problem such as the need to upsize the apparatus. Therefore, the pressure during production is preferably more than 0.1 mmHg, and particularly 70,000. The pressure for producing the above high molecular weight aliphatic polyester is 0.1
It is more preferably larger than 1 mmHg and larger than 1 mmHg. When the pressure fluctuates during manufacturing, the final ultimate pressure should be within the above range.

The production temperature is 120 ° C. to 350 ° C., preferably 140 ° C. to 300 ° C., more preferably 140 ° C. to 250 ° C. The reactor is not limited as long as the above conditions can be realized. For example, a surface renewal type twin-screw kneader, a surface renewal type thin film reactor, a circulation type device having a free fall zone as a polymerization accelerating region as disclosed in JP-A-7-292097, a rotary tube oven, etc. can be manufactured. It is suitable. The rotary tube oven can 1) rotate a sample in a thin film along a cylindrical surface heater to increase the evaporation surface area, and 2) provide a sufficient distance between the heating surface and the condensation surface. Since the components that are close to each other and are difficult to distill in a normal flask reaction are easily distilled, the surface area of the heating surface of the sample can be made large, and the components jumping from the heating surface reach the condensation surface without condensing. it can. As a result, in the esterification, the dealcoholization (dehydration) reaction can proceed efficiently, and also in the subsequent deglycolization reaction or dediester (or dedicarboxylic acid) reaction, the reaction can proceed efficiently.

The above apparatus is charged with diol and dicarboxylic acid (or its ester or acid anhydride), and esterification is carried out in a stream of inert gas (N ₂ ). The esterification temperature is preferably lower than the boiling point of the low-boiling substance of the starting diol and dicarboxylic acid (or its ester or acid anhydride). Continue the reaction and check that alcohol distillation (or dehydration) stops. Since the glycol removal reaction or the dediester (or decarboxylic acid) reaction requires a small amount of the catalyst, the temperature is once returned to room temperature and the catalyst is added. However, the catalyst at this time can be already added at the time of charging the raw material diol or dicarboxylic acid (or its ester or acid anhydride).
The catalyst that can be used is a metal compound such as titanium, zinc, germanium, iron, tin (including hydrates), and examples thereof include zinc acetate, zinc stearate,
Commercial products such as zinc octanoate can be used. The amount of catalyst added is based on the total amount of monomers charged.
The amount may be 0.0001 mol% or more and 10 mol% or less, preferably about 0.0005 mol% or more and 1 mol% or less. After the catalyst is added, the temperature is gradually raised so that bumping of the esterified prepolymer does not occur, and the pressure inside the system is reduced to a predetermined pressure and temperature. In the granular fertilizer and the method for producing the same of the present invention, a product obtained by binding the aliphatic polyester represented by the general formula (I) with a linking agent can also be used.

The linking agent is a compound having two or more functional groups in the molecule capable of reacting with the terminal of the aliphatic polyester, and the functional groups are isocyanate, carboxylic acid,
Carboxylic anhydrides, carboxylic acid esters, hydroxyl groups and the like are used. Most preferably, the number of functional groups is two. Preferable examples of the aliphatic polyester using a linking agent include resins obtained by linking polytetramethylene succinate and polytetramethylene adipate with hexamethylene diisocyanate.

Specific examples of the aliphatic polyester having a polycondensation structure of hydroxycarboxylic acid used in the coating layer of the present invention include polylactic acid, polyglutamic acid and polycaprolactone. Of these, polycaprolactone is preferable because it is easily synthesized.
The ester group content in the aliphatic polyester used in the coating layer of the present invention is preferably low in order to exhibit low elution, and the polyester group content per number average molecular weight of 1000 is preferably 16 or less, more preferably 12 or less. Preferably 8
The following are the most preferable.

As the polyolefin wax which is a component of the coating layer of the granular fertilizer of the present invention, a polyolefin, for example, a wax of a homopolymer or a copolymer of two or more kinds of olefins such as ethylene, propylene and butadiene can be used. When an unsaturated bond remains in the molecule, it may be hydrogenated. Further, it may have a straight-chain structure or a branched structure.
The wax is preferably polyethylene wax. As the polyethylene wax, a wax containing 50% by weight or more of ethylene is preferable.

In order to facilitate coating, the density of the wax is preferably low, and the wax has a density of 0.860 g / cm ³ or more and 0.9 or more.
It is preferably 40 g / cm ³ or less. From the viewpoint of easy synthesis, it is preferably 0.900 g / cm ³ or more. The number average molecular weight of the wax is preferably high from the viewpoint of easy coating and storage stability, and is 300 or more, more preferably 570 or more, still more preferably 1000 or more, but the degradability after disposal ( The number average molecular weight is 10,000 or less and the weight average molecular weight is 70,000 or less, and the number average molecular weight is 6000 or less and the weight average molecular weight is 50,000 or less. If it is less than 300, the melting point is close to room temperature and the performance of the coated fertilizer cannot be kept stable. The number average molecular weight Mn and the weight average molecular weight Mw of the aliphatic polyester of the present invention are polystyrene conversion values measured by gel filtration chromatography (GPC). The number average molecular weight Mn and the weight average molecular weight Mw of the polyolefin wax of the present invention are values in terms of polyethylene measured by gel filtration chromatography (GPC). Next, a method for producing the coated granular fertilizer of the present invention will be described.

The coating material includes the above aliphatic polyester and polyolefin wax. The aliphatic polyester and the polyolefin wax may be used as a mixture of two or more kinds. The content of the aliphatic polyester in the coating material is 5 to 80% by weight, preferably 20 to 70%.
% By weight. If it is less than 5% by weight, the moldability is poor and
If it exceeds 5% by weight, the water permeability is too fast, which is not preferable.
The content of the polyolefin wax in the coating material is 20 to
It is 95% by weight, preferably 30-80% by weight. 20
If it is less than 100% by weight, the water permeability is too high, and if it is more than 95% by weight, the film formability is poor and it is not preferable.

In order to adjust the properties of the coating layer such as mechanical properties, fertilizer elution property and degradability, the coating material may contain other components in addition to the aliphatic polyester or the polyolefin wax. A compatibilizer may be appropriately used in the coating layer. Examples of the compatibilizer include unsaturated aliphatic carboxylic acid-modified polyolefins such as maleic anhydride modified polypropylene and maleic anhydride modified polyethylene, aliphatic carboxylic acid modified products of the above polyolefin wax used in the present invention, and SBS (styrene- Styrene-based thermoplastic elastomer such as butadiene-styrene) and SEBS (styrene-ethylene-butylene-styrene), EPR
Examples thereof include rubber such as (ethylene-propylene). The amount of the compatibilizer in the coating layer is preferably 0.01% by weight or more in order to obtain the effect of addition, but it is usually 75% by weight or less because it is difficult to satisfy both elution control of fertilizer and decomposability. It is preferably 50% by weight or less, more preferably 20% by weight or less, still more preferably 10% by weight or less.

Insoluble fillers such as talc, calcium carbonate, diatomaceous earth, and metal oxides can be used as the combined component. The amount of the insoluble filler in the coating material is preferably 0.01% by weight or more in order to obtain the effect of addition, but 75% by weight is difficult because it is difficult to achieve both suppression of fertilizer elution and decomposability.
The following is preferable, and 50% by weight or less is more preferable. Further, an aliphatic polymer such as an ethylene / vinyl acetate copolymer or an ethylene / vinyl alcohol copolymer as a water permeability modifier, or a surfactant can also be used. The amount of the moisture permeability adjusting agent in the coating material is 0.
It is preferably 01% by weight or more, but it is difficult to achieve both suppression of moisture permeability and decomposability.
It is more preferably not more than 10% by weight, still more preferably not more than 10% by weight.

It is also preferable to use a photodegradable additive because it can accelerate the decomposition of the coating material used in the granular fertilizer of the present invention. Examples of the photodegradable additive include transition metal complexes, oxidation accelerators, and photosensitizers. Examples of the transition metal complex include those in which the complexing agent is bound to the metal via oxygen and the metal is a transition metal. For example, iron acetylacetonate, iron acetonyl acetonate, cobalt acetylacetonate, cobalt acetonyl acetonate, etc., or dialkyldithiocarbamate of iron, nickel, zinc or tin, dithiophosphate, xanthate, or benzthiazole. These may be added alone or in combination of two or more. Preference is given to the combined addition of iron or cobalt acetylacetonate or iron acetonyl acetonate and iron, nickel, zinc or tin dialkyldithiocarbamates. The concentration of the complex in the coating material is 0.0001 to 0.5% by weight, more preferably 0.005 to 0.2% by weight.
It is.

It is preferable to pre-blend the components of the above-mentioned coating material to obtain uniformity in the color of the coating. For the pre-blending, a method for producing a resin composition can be used. The apparatus used for preblending is not particularly limited, but a kneader or an extruder can be used. The temperature range of the preblend is preferably 20 ° C lower than the lowest melting temperature of the resins used to 20 ° C higher than the highest melting temperature of the resins to be used. It is determined according to the components used in combination, particularly the polymer component. . The weight percentage of the coating material to the coated granular fertilizer, that is, the coating rate is preferably 0.5.
% Or more and 50% or less, more preferably 1% or more and 40% or less, and further preferably 2% or more and 25% or less. 0.
If it is less than 5%, defects such as pinholes are likely to occur in the film, making it difficult to control the elution of fertilizer. On the other hand, if it exceeds 50%, the elution of fertilizer will be delayed more than necessary, and an excessive burden on the coating process, for example, a large amount of use of the coating material and a large amount of energy consumption will be caused.

There is no limitation on the components of the granular fertilizer used in the present invention. For example, (1) urea, acetaldehyde condensed urea, isobutyraldehyde condensed urea, formaldehyde condensed urea, guanylurea sulfate, oxamide, and other nitrogen-containing organic components, or (2 ) Ammonium nitrate, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, ammonium sulfate, ammonium salts such as ammonium chloride, potassium nitrate, potassium phosphate, potassium sulfate, potassium salts such as potassium chloride, calcium nitrate, calcium phosphate, calcium sulfate, calcium chloride, etc. Calcium salts, magnesium salts such as magnesium nitrate, magnesium phosphate, magnesium sulfate, magnesium chloride, ferrous nitrate, ferric nitrate, ferrous phosphate, ferric phosphate, ferrous sulfate, ferric sulfate, chloride Ferrous iron, second chloride Iron salts and the like, these single salt,
And an inorganic component such as a double salt composed of a plurality of components, and (3)
Examples thereof include a composite of an organic component and an inorganic component.

The shape of the granular fertilizer may be spherical, columnar or angular, but spherical is preferable from the viewpoint of controllability of the elution rate. The diameter of the granular fertilizer is preferably 0.5 to 10 mm. If the diameter of the granular fertilizer is 0.5 mm or less, the ratio of the coating surface area per unit fertilizer weight of the coating becomes large, the thickness of the coating itself becomes thin, the control of the elution rate becomes insufficient, and if the diameter is 10 mm or more, fertilization is performed. It is hard to do and not practical. The method of coating the fertilizer with the coating material can be roughly classified into a solvent method and a solventless method. In the solvent method, the above-mentioned coating material dissolved or dispersed in a suitable solvent is sprayed onto fertilizer, or the fertilizer is immersed in a coating material solution or dispersion liquid, and then the solvent is removed and dried. Drying with a heated air stream is particularly efficient for drying. When coating, it is preferable that the fertilizer particles are rolled or float-rotated in order to make the coating thickness uniform. The solvent used for the coating material solution or dispersion varies depending on the composition of each aliphatic polyester or coating material, but is chloroform, methylene chloride, o-dichlorobenzene, trichlorobenzene, trichloroethylene, tetrachloroethylene, o-chlorophenol, N. -Methylpyrrolidone can be used as a typical example, and many others 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 0 to 120 ° C, preferably 10 to 100 ° C.

In the solventless method, a coating material melt or melt dispersion is used in place of the coating solution or dispersion in the solvent method. In that case, the melting temperature is 80 to 250 ° C., preferably 130 to 230 ° C. from the viewpoint of adjusting viscosity and preventing thermal decomposition.
However, the appropriate temperature is determined according to the individual aliphatic polyester and the component used in combination, particularly the polymer component. A jet tower, a rotary pan, a rotary drum, or the like can be used as the coating device. The melt viscosity of the polyolefin wax used in the present invention is preferably 0.5 or more and 450 poises or less at 140 ° C., more preferably 0.5 or more and 300 poises or less, in order to facilitate molding during preblending or solventless coating.
Most preferably, it is 0.5 or more and 100 poise or less.

The fertilizer release property of the produced coated granular fertilizer can be examined by a fertilizer dissolution test in water. This method is effective not only for simulating fertilizer release in rice fields and hydroponics, but also for predicting fertilizer release in soil of fields. The disappearance of the coating can be examined by a long-term soil burying test of coated granular fertilizer or a short-term accelerated test in activated sludge. The degradability of the coating of the produced coated granular fertilizer was performed by forming a pinhole in the coating of the coated fertilizer, immersing it in water at 30 ° C for 2 weeks, and using an empty coating from which the fertilizer was removed. The empty coating was placed in a resin net and embedded in soil. After 12 months, the coating is dug out, and only the sample that clearly retains the coating prototype is placed in a V-type mixer with rotating blades and mixed by stirring for 30 minutes. Then, it was passed through a 10-mesh sieve, and the ratio of the coating that passed through to the test coating was taken as the decomposition rate. Degradation rate 100% if the original pattern is not retained and only traces or no traces are observed
And The storage stability was measured by measuring the change in the elution performance of the coated fertilizer before and after storage after storing it in a thermostat at 40 ° C. for 7 days. For the change in elution, the elution rate on the third day of elution measurement was compared.

[0038]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below with reference to Examples and Comparative Examples of the present invention. GPC for the measurement of molecular weight
Was used. These details are as follows.

Normal temperature GPC: Model used: Tosoh GPC HCL-8020 type solvent: CHCl ₃ / MeOH = 98/2 (vol ratio) Sample concentration: 1 mg / ml Column temperature: 40 ° C Molecular weight standard polystyrene High temperature GPC: Model used: Waters GPC 150C type solvent: 1,2,4-trichlorobenzene sample Concentration: 20 mg / 15 ml column: Showdex AT-807S 1 bottle Tosoh TSK-gel GMH-H6 2 columns Temperature: 145 ° C. molecular weight standard polystyrene An example will be described.

Example 1 A resin (Bionole 1010, Showa High Polymer Co., Ltd.) obtained by linking polyethylene succinate with a polyvalent isocyanate was used.
g, number average molecular weight 4300, weight average molecular weight 3800
0, 25 g of polyethylene wax having a density of 0.910 g / cm ³ (melt viscosity 4300 CPS at 140 ° C.), maleic anhydride-modified polyethylene wax (density 0.95
0 g / cm ³ , number average molecular weight 3000, melt viscosity at 140 ° C. 3500 CPS, acid value 30 mg KOH / g) 5
g was placed in a Labo Plastomill (manufactured by Toyo Seiki Co., Ltd.) at 150 ° C. and kneaded to obtain a composition.

Next, 200 g of fertilizer (potassium phosphorous nitrate) of 5 to 9 mesh (standard sieve manufactured by Tyler) used for coating is charged in a rotary drum type coating device, the drum is rotated, and hot air at 90 ° C. is supplied. did. 16 g of the above composition of the coating material was added to 384 g of the solvent trichlorethylene in the liquid tank, and 30 ml of the coating liquid (4% by weight of the coating material) prepared by stirring while being close to the boiling point of the solvent was pumped.
/ Min to the spray nozzle in the drum to obtain coated granular fertilizer. A coated granular fertilizer having a coverage (versus coated fertilizer) of 7% by weight was obtained. The color of the coating was uniform. The nitrogen elution rate of the obtained coated granular fertilizer in water at 25 ° C. was analyzed by an analytical instrument. The results are shown in Table 2. The coated granular fertilizer had good storage stability, and its degradability after the completion of elution was confirmed.

Examples 2 to 18 In the same manner as in Example 1, coated granular fertilizers were produced using the coating materials shown in Tables 1 and 3. However, in the table, “with preblend” means that kneading was carried out by a Labo Plastomill as in Example 1, and “without preblending” had the same composition as that of Example 1 and was used without being kneaded by a Laboplast mill. Refers to. Regarding Examples 1 to 4, the coating state is also shown in Table 1. The coating color was uniform in Example 1 and non-uniform in Examples 2 to 4, but the coating state was normal in all Examples. The nitrogen elution rates measured in the same manner as in Example 1 are shown in Tables 2 and 4. All of them had good storage stability, and the degradability after the completion of elution was confirmed.

Comparative Examples 1 and 2 A coated granular fertilizer was produced in the same manner as in Example 1 except that only one of the aliphatic polyester and the polyolefin wax was used. The production results are shown in Table 1. All of them contained lumps or the coating was peeled off, and good coated granular fertilizer could not be obtained.

Comparative Example 3 In the same manner as in Example 1, a coated granular fertilizer was produced using the coating materials shown in Table 3. When the storage stability was examined in the same manner as in Example 1, the nitrogen elution rate after 3 days was increased from 4% to 40%.

[0045]

[Table 1]

[0046]

[Table 2]

[0047]

[Table 3]

[0048]

[Table 4]

Note 3 in Table 3 above * 1) Polyolefin wax is as follows: Polyethylene wax A (number average molecular weight 4300, weight average molecular weight 38,000, density 0.910 g / cm ³ , 1
Melt viscosity at 40 ° C. 4300 CPS Polyethylene wax B (number average molecular weight 1100, weight average molecular weight 4800, density 0.930 g / cm ³ , 14
Melt viscosity at 0 ° C. 110 CPS) Polyethylene wax C (number average molecular weight 600, weight average molecular weight 640, density 0.920 g / cm ³ , 140 ° C.)
Melt viscosity at 6 CPS) Polyethylene wax D (number average molecular weight 340, weight average molecular weight 380, density 0.910 g / cm ³ ) Paraffin wax (number average molecular weight 280, weight average molecular weight 290, density 0.910 g / cm ³ ) * 2) Aliphatic polyester is as follows: Bionole 1010 (Showa High Polymer) Aliphatic polyester C4C4 (polybutylene succinate, number average molecular weight 120,000, weight average molecular weight 400)
000) Aliphatic polyester C4C2O (polybutylene eicosandioate, number average molecular weight 37,000, weight average molecular weight 120,000) * 3) Master batch containing a photolytic agent: iron acetylacetonate 2% by weight, nickel dibutyldithiocarbamate complex 0.2 Weight% included

[0050]

[Table 5]

[0051]

As described above, the coated granular fertilizer of the present invention is excellent in storage stability without causing cracks or fractures in the coating during production and storage, and enables control of fertilizer elution in a wide range, and After the fertilizer is eluted, the coating layer can be dissipated by the degradability of the coating material.

Claims (14)

[Claims] 1. A coated granular fertilizer having a coating layer containing 5% by weight or more and 80% by weight or less of an aliphatic polyester and 20% by weight or more and 95% by weight or less of a polyolefin wax. 2. The coated granular fertilizer according to claim 1, wherein the aliphatic polyester is an aliphatic polyester represented by the general formula (I). Embedded image (N is a number average molecular weight Mn of 1,000 or more and 1,000
It represents the degree of polymerization required to reach 50,000 or less. R ¹ is an aliphatic hydrocarbon group having 2 to 20 carbon atoms, and R ² is an aliphatic hydrocarbon group containing 0 and having 24 carbon atoms or less. R ¹ ,
R ² may each include two or more types). 3. The aliphatic polyester n is 1,0 when the number average molecular weight Mn of the polyester is more than 15,000.
The coated granular fertilizer according to claim 2, which has a degree of polymerization required to become not more than 0,000. 4. The coated granular fertilizer according to claim 1, wherein the aliphatic polyester is polyhydroxycarboxylic acid. 5. The coated granular fertilizer according to claim 1, wherein the aliphatic polyester is polylactic acid. 6. The coated granular fertilizer according to claim 1, wherein the aliphatic polyester is polycaprolactone. 7. The coated granular fertilizer according to claim 1, wherein the polyolefin wax is polyethylene wax. 8. The polyolefin wax has a density of 0.86.
0 g / cm ³ or more 0.940 g / cm ³ or less of coated granular fertilizer according to claim 1 is a low density polyethylene waxes. 9. The coated granular fertilizer according to claim 1, wherein the polyolefin wax has a number average molecular weight of 300 or more and 10,000 or less. 10. The coated granular fertilizer according to claim 1, wherein the number average molecular weight of the polyolefin wax is 570 or more and 10,000 or less. 11. The coated granular fertilizer according to claim 1, wherein the polyolefin wax has a number average molecular weight of 1,000 or more and 10,000 or less. 12. 0.01 or more as a moisture permeability adjusting agent 75
2. The coated granular fertilizer according to claim 1, further comprising a wt% or less of an aliphatic polymer and / or a surfactant in a coating layer. 13. A coating layer containing an aliphatic polyester and a polyolefin wax in a mixed manner.
Coated granular fertilizer. 14. The method for producing coated granular fertilizer according to claim 1, wherein a liquid obtained by dissolving or dispersing the coating material in a solvent is sprayed onto the granular fertilizer and dried by a heated air stream.