JPH10324587A - Granular fertilizer coating agent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily obtain a granular fertilizer good in fertilizer component elution delaying property and which is not blocked by coating the fertilizer with a coating agent consisting of the polyurethane resin derived from a polyol component and a polyisocyanate component and contg. an oxyalkylene group of a specified number of carbon atoms and an ester group. SOLUTION: The adhesion of the granular fertilizer coating polyurethane resin to the fertilizer is improved by incorporating 0.5-20 wt.%, preferably 1-17 wt.%, 3-12C oxyalkylene group. The ester group content in the polyurethane resin is controlled to 1-10 wt.%, preferably 1.5-8 wt.%, from the standpoint of the hydrolyzability and controlled releasability of the coating film component remaining after the elution of the fertilizer component. Vegetable oil, low molecular multifunctional alcohols, carboxylic acids, alkylene oxide adduct of polyester., etc., are used as the polyol component. Diisocyanate monomers, preferably diphenylmethane diisocyanate, is used as the diisocyanate group.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a coating for granular fertilizer. More specifically, the present invention relates to a coating agent which has a good delay in elution of fertilizer components, has excellent blocking adhesion, and excellent adhesion to fertilizers, and can form a film in a short time without using a solvent. .

[0002]

2. Description of the Related Art In order to maintain the effects of the components of granular fertilizers, coated fertilizers in which various synthetic polymer materials are coated on the surface of granular fertilizers have been studied. Among such coating materials, urethane-based coating materials include, for example, a solventless coating agent comprising a polyisocyanate, a phenol-formalin condensate, a hydroxy group-containing softener, and a catalytic amine (Japanese Patent Application Laid-Open No. Sho 62-14474); Coating agent obtained by dissolving polyisocyanate and polyol derived from wool or lanolin in an organic solvent (Japanese Patent Laid-Open No. 4-305
No. 085) has been proposed.

[0003]

However, the above method has a problem of blocking the fertilizer component, and also has a problem of a delay in elution of the fertilizer component. It is necessary to repeat coating and drying many times in order to obtain a predetermined coating thickness, which is troublesome.

[0004]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have conducted intensive studies to obtain a solvent-free type coating agent which can form a film having good retardation and no blocking property. The present invention has been reached. That is, the present invention relates to a polyol component (A) and a polyisocyanate component (B), wherein 0.5 to 20% by weight of an oxyalkylene group having 3 to 12 carbon atoms and 1 to 10% by weight in a molecule. A granular fertilizer coating agent comprising a polyurethane resin containing an ester group (—COO—) of the following: a polyol component (A) and a polyisocyanate component (B), wherein the polyol component (A) and / or The polyisocyanate component (B) contains an oxyalkylene group having 3 to 12 carbon atoms and an ester group (—COO—) in the molecule,
The content of oxyalkylene units is 0.5 to 20% by weight based on the total weight of (A) and (B), and the ester group content is 1 to 20 based on the total weight of (A) and (B). 1
A coating material for a granular fertilizer, which is a two-component polyurethane-forming composition in an amount of 0% by weight; and a granular fertilizer further coated with the coating material.

[0005]

DETAILED DESCRIPTION OF THE INVENTION The polyurethane resin of the present invention has an oxyalkylene group and an ester group (-CO
O-). As an oxyalkylene group, from the point of delay of elution of fertilizer components and adhesion to fertilizer,
Usually, it is an oxyalkylene group having 3 to 12 carbon atoms, preferably an oxyalkylene group having 3 to 6 carbon atoms. If the number of carbon atoms is 2 or less, the fertilizer component may be excessively eluted, and if the number of carbon atoms is 13 or more, the adhesion to the fertilizer may decrease, which is not preferable.

[0006] The content of oxyalkylene units in the polyurethane resin is usually 0.5 to 20% by weight, preferably 1 to 17% by weight, from the viewpoint of delay in elution of fertilizer components and adhesion to fertilizers. %. If it is less than 0.5% by weight, the fertilizer component may be excessively eluted, and if it exceeds 20% by weight, the adhesion to the fertilizer may be reduced, which is not preferable.

The content of the ester group in the polyurethane resin is usually 1 to 10% by weight, preferably 1.5 to 8%, in view of the hydrolyzability of the remaining film component after elution of the fertilizer component.
% By weight. If it is less than 1% by weight, the hydrolyzability of the film after elution of the fertilizer component is poor, and if it exceeds 10% by weight, the film is hydrolyzed during the elution of the fertilizer component and the sustained release property is impaired.

[0008] 3 to 12 carbon atoms in the polyurethane resin
The method for introducing the oxyalkylene group and ester group is not particularly limited, and may be derived from the polyol component (A) or the polyisocyanate component (B). further,
The two groups may be from a single component or from different components.

The coating material for granular fertilizer in the present invention is a polyurethane resin derived from a polyol component (A) and a polyisocyanate component (B), and comprises a polyol component (A) and a polyisocyanate component (B). 2
It is a component-based polyurethane resin. The content of the oxyalkylene unit is usually 0.5 to 20% by weight, preferably 0.5 to 20% by weight, based on the total weight of (A) and (B), from the viewpoint of delay in elution of the fertilizer component and adhesion to the fertilizer. Is 1 to 17% by weight. Further, the ester group content is determined from the viewpoint of the delay of elution of the fertilizer component and the adhesion to the fertilizer, (A)
It is usually 1 to 10% by weight, preferably 1.5 to 8% by weight, based on the total weight of (B) and (B). If it is less than 1% by weight, the hydrolyzability of the film after elution of the fertilizer component is poor, and if it exceeds 10% by weight, the film is hydrolyzed during the elution of the fertilizer component and the sustained release property is impaired.

Examples of the polyol component (A) include vegetable oils and derivatives thereof (eg, castor oil, alkylene oxide adducts of castor oil, modified polyhydric alcohols of castor oil fatty acids, etc.) and alkylene oxide additions of low molecular weight polyfunctional alcohols. (Eg, glycerin, trimethylolpropane propylene oxide, butylene oxide, homo-adducts and co-adducts of styrene oxide), low-molecular weight polyfunctional carboxylic acid alkylene oxide adducts (eg, dodecane diacid propylene oxide, butylene oxide) Styrene oxide homo-adducts, co-adducts, etc.) alkylene oxide adducts of low molecular weight polyfunctional polyesters (for example, propylene oxide of polyester of glycerin and dodecanedioic acid,
Butylene oxide, a single adduct of styrene oxide, a co-adduct and the like); and a mixture of two or more of these. The number of functional groups (hydroxyl groups) in one molecule of the polyol is usually 2 to 10 in view of film forming property, and preferably 2 to 10.
~ 6.

In order to impart film-forming curability at a low temperature, an amine-based polyol (A-1) is optionally used.
May be used in combination as a part of the polyol component. Examples of the amine-based polyol (A-1) include, for example, C3 to C3.
20 oxyalkylenated polyamines (such as a 4-mol adduct of propylene oxide with ethylenediamine, a 5-mol adduct of propylene oxide with diethylenetriamine, a 6-mol adduct of propylene oxide with triethylenetetramine, and a 4-mol adduct of tolylenediamine with ethylene oxide); Amines (tripropanolamine, propylene oxide 3 of tripropanolamine)
Mole adduct). Among them, those preferred from the viewpoint of the curing speed of the coating and the blocking resistance of the cured coating are described above, and those containing at least three hydroxyl groups in the molecule are more preferred. The tertiary nitrogen content based on the amine polyol (A-1) is usually 0.01 to 1.5 with respect to the total weight of (A) and (B) in order to impart curability at room temperature. % By weight, preferably 0.
1 to 1.0% by weight. If it is less than 0.01% by weight, the curing rate at room temperature will be slow, and if it exceeds 1.5% by weight, the curing rate will be too fast, and it may be difficult to form a uniform film.

Further, a polyurethane polyol prepolymer obtained by previously reacting the above polyol with a small amount of polyisocyanate may be used as the polyol component (A). The equivalent ratio (OH / NCO) of the hydroxyl group of the polyol to the isocyanate group of the polyisocyanate is usually (1.2 to 100) / 1, preferably (2 to 50) / 1.
It is.

The polyol component (A) may contain other known components such as a polymer and a solvent, if necessary.

As the polyisocyanate component (B),
For example, diisocyanate monomers [aromatic isocyanates (tolylene diisocyanate, diphenylmethane diisocyanate, etc.), araliphatic isocyanates (xylylene diisocyanate, α, α, α ', α'-tetramethylxylylene diisocyanate, etc.), alicyclic isocyanates (isophorone Diisocyanate, dicyclohexylmethane diisocyanate, etc.), aliphatic isocyanates (hexamethylene diisocyanate, dodecamethylene diisocyanate, etc.)]; modified products of these diisocyanate monomers (isocyanurate, buret, uretdione, trimethylolpropane adduct, etc.) A polyisocyanate prepolymer (eg, a reactant of a polyol with an excess of an isocyanate compound); and two or more of these. Mixtures are mentioned.
Of these, preferred are highly reactive aromatic diisocyanate monomers, modified products and prepolymers, and particularly preferred are diphenylmethane diisocyanate monomers and prepolymers thereof. The number of functional groups (isocyanate groups) in one molecule of the polyisocyanate is usually 2 to 10, preferably 2 to 6, from the viewpoint of film-forming properties.

Further, a polyurethane polyisocyanate obtained by previously reacting the above-mentioned polyisocyanate with a small amount of a polyol may be used as the polyisocyanate component (B). The equivalent ratio (NCO / OH) of the isocyanate group of the polyisocyanate to the hydroxyl group of the polyol is usually (1.2 to 100) / 1, preferably (2 to 50) /
It is one.

The polyisocyanate component (B) may contain other known components such as a polymer and a solvent, if necessary.

The equivalent ratio (OH / NCO) of the hydroxyl group of the component (A) to the isocyanate group of the component (B) is usually (85 / NCO).
To 115) / (115 to 85), preferably (90 to 1)
10) / (110-90). If the ratio is out of the above range, sufficient coating strength and durability may not be obtained.

In the present invention, the method of mixing (A) and (B) and the method of using it as a coating agent are not particularly limited, and a method in which (A) and (B) are mixed in advance and used as a coating agent, And a method in which a solvent (for example, toluene, xylene, chloroform, tetrahydrofuran, or dimethylformamide) diluted with a urethane resin derived from (B) is used as the coating agent. Although it depends on the viscosity, the resin concentration is usually 5 to 100%. Preferably, there is no need to use a diluent, and there is an advantage that the drying step can be omitted.

If necessary, the coating agent of the present invention may contain other known components such as a polymer, a dispersant, a surfactant and an inorganic pigment. Specific examples of the above polymer include polyester resin, polyamide resin, epoxy resin, vinyl chloride-vinyl acetate copolymer resin, and the like. Examples of inorganic pigments include kaolin, talc,
Examples include calcium carbonate, mica, clay, and calcium silicate.

The fertilizer to which the coating agent of the present invention can be used is not particularly limited as long as it is granular. For example, monofertilizers such as urea, ammonium sulfate, ammonium nitrate, potassium chloride, and phosphorus ammonium sulfide, ammonium phosphide, and potassium nitrate ammonium can be used. Compound fertilizers such as those described above are typical examples.

As a method of coating the granular fertilizer when the coating agent of the present invention is used, a method of spraying and atomizing the granular fertilizer in a fluid floating state, and a method of spraying and atomizing the granular fertilizer in a rotating pan. Method. The coating film cures in 10 to 20 minutes after application, but 60 to 100
If it is heated with hot air at ℃, it can be cured in a shorter time.

The coated granular fertilizer thus obtained does not cause a blocking phenomenon during coating and does not block during storage. Further, the coating agent can be coated to an arbitrary thickness in a short time, and when the obtained granular fertilizer is immersed in water, the elution amount of the fertilizer component can be appropriately controlled.

[0023]

The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto. In the following, "parts" indicates parts by weight and "%" indicates% by weight.

The meanings of the abbreviations of the raw materials used in Production Examples, Examples and Comparative Examples are as follows. [Polyol (A) component] A1: Castor oil (molecular weight: 1,000, hydroxyl value: 161) A2: Castor oil propylene oxide adduct (molecular weight: 1)
A3: castor oil (molecular weight 1000, hydroxyl value 161) 7
00 parts and 300 parts of a propylene oxide adduct of pentaerythritol (molecular weight 400) (hydroxyl value 2
80) [Polyisocyanate (B) component] B1: Reaction product of propylene oxide adduct of glycerin (molecular weight 3000) and diphenylmethane diisocyanate (NCO% 15.1) B2: Propylene oxide adduct of trimethylolpropane (molecular weight 700) Reaction product of diphenylmethane diisocyanate (NCO% 18.9) B3: Reaction product of castor oil and diphenylmethane diisocyanate (NCO% 19.1) [Amine-based polyol (A-1) component] C1: Propylene oxide adduct of ethylenediamine (molecular weight) 300) C2: Propylene oxide adduct of ethylenediamine (molecular weight 400)

Examples 1 to 5 Polyol component (A), polyisocyanate component (B) and amine-based polyol (A-
A coating agent was prepared using 1). The coating on granular fertilizer is
Using a fluid coating apparatus with a spouted bed, 60 g of each coating agent is added as a solid content to 1 kg of a commercially available ammonium sulfate fertilizer having an average particle diameter of 3 to 5 mm, which is suspended in the apparatus, by spraying and atomizing, and coating is performed. After curing at room temperature, a coated granular fertilizer of the present invention having a coating agent coverage of 6% by weight was obtained.

[0026]

[Table 1]

Comparative Example 1 According to the method described in Example 3 of JP-A-4-305085, 10 parts of lanolin alcohol, 2,4-
The operation of immersing the granular fertilizer used in Example 1 in a solution obtained by mixing and dissolving 10 parts of tolylene diisocyanate and 50 parts of tetrachloroethylene and drying it at 100 ° C. for 20 minutes is repeated to obtain a coated granular material having a coverage of 10% by weight. Got fertilizer.

Comparative Example 2 A benzyl ether resin prepared from 1 mol of phenol and 1.2 mol of formaldehyde according to the method described in Example 1 of JP-A-62-144474.
A solution prepared by mixing and dissolving 50 parts of castor oil and 50 parts of diacetone alcohol mixture with 50 parts of diphenylmethane diisocyanate was subjected to the same operation as in Example 1 while introducing dimethylamine-containing nitrogen gas. A coated granular fertilizer was obtained.

Comparative Example 3 A 25% solution was prepared by dissolving a polycaprolactone resin ("Placcel H7000", manufactured by Daicel Chemical Industries, Ltd.) in methyl ethyl ketone, and the granular fertilizer used in Example 1 was immersed in this solution and heated at 100.degree. The operation of drying for 20 minutes was repeated to obtain a comparative coated granular fertilizer having a coverage of 10% by weight.

10 g of each of the coated granular fertilizers obtained in Examples 1 to 5 and Comparative Examples 1 to 3 was separately placed in 200 ml of water and allowed to stand at 25 ° C., and the conductivity of the aqueous phase was measured. The elution rate was calculated. Table 2 shows the dissolution rate of ammonium sulfate.

[0031]

Table 2-Dissolution rate (%) of ammonium sulfate in coated fertilizer 1 After 2 months After 3 months After 4 months After 5 months 5 months -------------------------- Example 10 13.0 30.2 56.7 82.3 2 20 55.3 55.9 80.3 97.5 30 33.2 69.1 85.3 99.2 40 12.7 29. 3 52.9 80.3 50 24.9 52.7 77.9 95.9 60 30.0 62.9 87.4 96.7 70 29.3 59.3 86.2 94.7- −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−− Comparative example 1 1.0 1.5 1.6 5.5 5.5 90 .2 2 4.5 10.5 100 − − 3 100 − − − − −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−

[0032]

The coating agent for granular fertilizer of the present invention has the following effects. (1) An organic film can be formed on the surface of the granular fertilizer in a short time without using a solvent. (2) A uniform film can be formed even with a film thickness smaller than the conventional one. (3) The fertilizer can be given a delay over a long period of time, and the amount of the fertilizer component eluted into the soil can be controlled. (4) Since the resin film after the release of the fertilizer component is hydrolyzed by the acid or alkali in the soil, it does not finally remain in the soil.

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[Procedure amendment]

[Submission date] March 18, 1998

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

Claims (4)

[Claims] 1. A polymer derived from a polyol component (A) and a polyisocyanate component (B) and having a molecular weight of 0.5 to
20% by weight of an oxyalkylene group having 3 to 12 carbon atoms,
A coating material for granular fertilizer, comprising a polyurethane resin containing 1 to 10% by weight of an ester group (-COO-). 2. A composition comprising a polyol component (A) and a polyisocyanate component (B), wherein the polyol component (A) and / or the polyisocyanate component (B) have an oxyalkylene group having 3 to 12 carbon atoms in a molecule. Ester group (-
COO-), the content of oxyalkylene units is 0.5 to 20% by weight based on the total weight of (A) and (B), and the content of (A) and (B) is based on the total weight of (A) and (B). A coating material for granular fertilizer, which is a two-component polyurethane-forming composition having an ester group content of 1 to 10% by weight. 3. As part of the polyol component (A), 3
The coating material for granular fertilizer according to claim 2 or 3, comprising an amine polyol (A-1) having a valency or higher. 4. A granular fertilizer coated with the coating agent according to claim 1.