JPH0859382A - Coated granular fertilizer - Google Patents

Abstract

PURPOSE: To adjust the elution starting time of a fertilizer component by coating the surface of a granular fertilizer with a film consisting essentially of the amorphous polyolefin formed by copolymerizing propylene, ethylene and/or butene-1. CONSTITUTION: A coating film forming soln. prepared by dissolving an alkaline substance such as CaCO3 and an adhesive in solvent is applied on a granular fertilizer having 1-5mm average grain diameter to form a first coating film on the fertilizer surface. Subsequently, an amorphous polyolefin contg. 0-20wt.% ethylene, 1-70wt.% butene-1 and the balance propylene and having 1,000 to 20,000 number average mol.wt. as the main component and an alkaline water-soluble polymer such as an isobutylene-maleic anhydride copolymer are mixed, and the mixture is dissolved in solvent to form a second coating film forming soln. The second coating film forming soln. is sprayed over the first film-coated granular fertilizer placed on a rotating coating dish to form a second coating film having 5-200μm thickness, and a coated granular fertilizer capable of adjusting the elution starting time of the fertilizer component is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coated granular fertilizer capable of controlling the elution start timing of fertilizer components in a water-containing medium or water.

[0002]

2. Description of the Related Art Conventionally, granular fertilizers capable of adjusting the elution start time have been developed for the purpose of expressing the effect of fertilizer components at an optimum time for plant growth. Among them, the technique of coating the granular fertilizer with a film made of polyolefin resin or rubber resin is well known. For example, coating with a polyolefin resin such as polyethylene (low density, medium density and high density type), polypropylene (homopolymer consisting of propylene alone, block and random copolymerized with a small amount of ethylene), polybutene, etc. is there. But,
These resin coatings are hard and have poor adhesion to the granular fertilizer inside the coating, and because the thermal expansion coefficients of these resins and granular fertilizers are very different, they are exposed to shocks during transportation or handling, or coated fertilizers. When stored in an environment where the temperature changes drastically, there is a drawback that the coating film is easily peeled off.
Further, the polyolefin-based resin coating has a high mechanical strength and is poorly balanced with the disintegration property when left in water, and there is a drawback in this respect as well.

[0003] When coated with an ethylene-vinyl acetate copolymer (hereinafter referred to as EVA) or an ethylene-ethyl acrylate copolymer (hereinafter referred to as EEA), a comonomer (vinyl acetate or ethyl acrylate) in EVA or EEA is used. If the content is low, it has similar performance to polyethylene resin, so it has the same drawbacks as the above polyethylene resin coating, and if the content of comonomer is high, the resin itself becomes sticky, and during the production and storage of coated fertilizer. It has the drawback that fertilizers tend to stick together. In addition, polyisoprene,
When coating with a rubber-based resin such as polybutadiene and isoprene, a copolymer of butadiene and styrene,
Since rubber generally has a large molecular weight and the viscosity when melted / dissolved is very high, it is difficult to work in the coating process of granular fertilizer, and it takes a long time for the decomposition and deterioration of the resin after the fertilizer is used. There are problems such as environmental pollution in the medium such as fields. On the other hand, when coating with waxes such as wax and low-molecular-weight polyethylene, the viscosity is low when the wax is melted / dissolved, so the coating work is easy, but the strength of the coating is weak, and the coating is formed during transportation / storage. It peels off. The following are prior art documents. (1) Fertilizer coated with a mixture of an olefin resin and EVA (Japanese Patent Publication No. 60-21952) (2) Fertilizer coated with a mixture of an olefin resin, EVA and a surfactant (Japanese Patent Publication No. 60-37074) (3) Coated fertilizer composed of an alkaline water-soluble polymer and an olefin resin (JP-A-4-202078) (4) Coated fertilizer composed of a highly water-swellable substance and a polyolefin resin (JP-A-4-202079) Issue bulletin) etc.

[0004]

As described above, none of the conventional coated granular fertilizers is satisfactory in terms of dissolution, release of fertilizer components and balance between mechanical strength and disintegration in water. In view of the above situation, the present inventors do not have the disadvantage of having a granular fertilizer coated with a film made of a polyolefin resin or a rubber resin,
The present invention has been completed by earnestly researching a material which is excellent in adhesiveness with granular fertilizer, balance between mechanical strength and disintegration in water, and has excellent non-tackiness of the surface, which easily decomposes a film which is unnecessary after fertilization.

In the present invention, the surface of the granular fertilizer is coated with a film containing an amorphous polyolefin obtained by copolymerizing propylene with ethylene and / or butene-1 as a main component. Hereinafter, the present invention will be described in detail. The amorphous polyolefin of the present invention is a copolymer composed mainly of propylene and / or butene-1 in which propylene and ethylene and / or butene-1 are copolymerized so that each monomer unit is randomly arranged. The ethylene content is 0 to 30% by weight, preferably 1 to 20% by weight, or the butene-1 content is 1 to 70% by weight, preferably 10 to 70% by weight, and the balance is It is propylene. The number average molecular weight of the copolymer is 1,000 to 20,000, preferably 2,000 to 1
It is in the range of 10,000. When the ethylene content of the amorphous polyolefin is 30% by weight or more, or the butene-1 content is 70% by weight or more, the surface tackiness of the coating film increases, and the coated granular fertilizers are likely to stick to each other. Further, if the number average molecular weight is less than 1,000, the mechanical strength of the coating film is small and the coating film peels off during transportation and storage. Further, if it exceeds 20,000, it becomes difficult to decompose. The amorphous polyolefin has a crystallinity of less than 20% by the DSC method, a softening point of 90 to 170 ° C. by the ring and ball method, and a melt viscosity at 190 ° C. of 200 to 20,000 cps. Those are preferable. Further, regarding the mechanical properties of the amorphous polyolefin alone at room temperature, the strength at break is 1 to 50.
kg / cm ^2, elongation at break from 20 to 1,200%, which tensile modulus is in the range of 10~500kg / cm ² is preferred.

The granular fertilizer in the present invention may be any conventional granular fertilizer, but is preferably a granular fertilizer which does not contain ammonia nitrogen or has a small ammonia nitrogen content. . Specific examples thereof include nitrogenous fertilizers such as urea, sodium nitrate, acetaldehyde condensed urea, and isoptylaldehyde condensed urea: fertilizer, calcined phosphorus, processed phosphate fertilizer, mixed phosphate fertilizer,
Phosphate fertilizer such as corrosive acid phosphate fertilizer: potassium sulfate, chloride chloride, potassium sulfate hard soil, potassium bicarbonate, silicic acid fertilizer and other fertilizers: phosphate fertilizer, nitrate fertilizer and other chemical fertilizers: organic fertilizer Etc .: and a granular fertilizer obtained by granulating a mixture of these fertilizers by a method known per se. The particle size of the granular fertilizer is not particularly limited, but it is generally preferably 1 to 5 mm. The granular fertilizer of the present invention is a chemical fertilizer mainly composed of a water-soluble and granular inorganic or organic fertilizer component, and is spherically processed with an organic spreader, for example, by a tilting plate type granulator, etc., an average particle size. Is 10 mmφ or less, preferably 1 to 5 mm
It is preferably used for φ. At this time, a first coat made of an alkaline substance can be formed on the surface of the granular fertilizer, and the surface of the coat can be coated with a second coat containing amorphous polyolefin as a main component.

The alkaline substance in the present invention is an alkaline earth metal carbonate, hydroxide or oxide, alkali metal carbonate, phosphate, silicate or organic acid salt, or alkylamides, or these. Is a mixture of. Specifically, it may be either an inorganic compound or an organic compound that exhibits alkalinity in an aqueous solution. In particular, an alkaline substance which is solid at room temperature and mildly reacts with water is preferable, and examples thereof include alkaline earth metal carbonates, hydroxides or oxides, alkali metal carbonates, phosphates or silicates. Such inorganic compounds and organic compounds such as alkali metal organic acid salts and alkylamides are preferable. Specific examples of such alkaline substances include calcium carbonate, calcium oxide, calcium hydroxide, magnesium carbonate, magnesium oxide, magnesium hydroxide, sodium carbonate, potassium carbonate, tripotassium phosphate, sodium silicate, sodium acetate, acetamide. , Propionamide, butyramide and the like.

Next, the granular fertilizer is coated with a film containing an amorphous polyolefin obtained by copolymerizing propylene and ethylene and / or butene-1 as a main component. The thickness of the film can be arbitrarily set according to the desired dissolution and release rate of the fertilizer component. It is usually 5 to 200 microns, preferably 10 to 100 microns. When the thickness of the coating is 5 microns or less, the mechanical strength of the coating is low and the coating may be cracked or peeled off during transportation and handling. On the other hand, when the thickness of the coating is 200 μm or more, the water disintegration of the coating is lacking, the permeation rate of water becomes almost zero, and the fertilizer components inside are not dissolved and released to the outside at all.

In the present invention, the method for coating granular fertilizer is
Although not particularly limited, depending on a state in which a composition containing an amorphous polyolefin as a main component is heated to a temperature equal to or higher than the softening point to be melted or is dissolved in a hydrocarbon organic solvent such as toluene or hexane at room temperature or under heating. The method of coating the granular fertilizer, cooling or drying, and removing the solvent, or the emulsion can be used to form the coating. At this time, a polyolefin-based resin such as polyethylene, polypropylene, or polybutene, an olefin-based copolymer such as EVA or EEA, or a rubber-based resin such as ethylene-propylene rubber, or wax containing amorphous polyolefin as a main component. The performance of the coating can be improved by adding a small amount of a known binder component such as. In addition, an alkali water-soluble polymer may be added to the amorphous polyolefin in order to control the disintegration property of the coating film in water. Further, in the present invention, an alkaline water-soluble polymer can be mixed with the amorphous polyolefin.

The alkali water-soluble polymer in the present invention is an isobutylene-maleic anhydride copolymer, and / or a maleimidated modified product thereof, or an alcohol modified product thereof. Specifically, if it is a polymer that is insoluble or slightly soluble in water but soluble in an alkaline aqueous solution,
Any polymer may be used. Specific examples of the preferred alkaline water-soluble polymer in the present invention include isobutylene-maleic anhydride copolymer, and / or maleimidated modified product thereof, alcohol modified product thereof, acrylic acid-acrylic acid ester copolymer, and cal. Poxymethyl cellulose (CMC) etc. can be mentioned. Among these, particularly preferred are isobutylene-maleic anhydride copolymer, and / or maleimide-modified modified isobutylene-maleic anhydride copolymer modified by maleimidizing the copolymer, and these. It is a modified alcohol. A copolymer containing a carboxylic acid or a carboxylic acid salt obtained by hydrolyzing an acid anhydride group of an isobutylene-maleic anhydride copolymer is not preferable because it is soluble in water. The isobutylene-maleic anhydride copolymer is extremely sparingly soluble in water (only a few wt% or less is dissolved in water at 25 ° C. after 2 weeks), but is soluble in an aqueous alkaline solution (carbonate at 25 ° C.). It is a polymer that dissolves in an aqueous potassium solution at 80% by weight or more after 2 weeks), and is soluble in organic solvents such as dimethylformamide and dimethylsulfoxide. Further, the maleimidated modified isobutylene-maleic anhydride copolymer is insoluble in water (solubility is 0% when immersed in water at 25 ° C. for 2 weeks), but soluble in an alkaline aqueous solution ( It is a polymer that dissolves in an aqueous potassium carbonate solution at 25 ° C. in 80% by weight or more after 2 weeks) and is soluble in various organic solvents.

The amount of the alkaline water-soluble polymer in the second coating layer of the coated granular fertilizer of the present invention can be arbitrarily changed according to the desired elution rate of the fertilizer component, but generally, the olefin polymer and the alkaline water are used. It is preferably in the range of 2 to 80% by weight, particularly 4 to 50% by weight based on the total weight of the soluble polymer. If the amount of the alkaline water-soluble polymer in the second coating layer is larger than the above range, the mechanical strength of the second coating layer will be reduced (generally becomes brittle), and the second granular material during handling, transportation and storage of the coated granular fertilizer will be deteriorated. The coating layer is cracked, so that the water permeability becomes too high, which makes it difficult to control the elution start time of the fertilizer component of the coated granular fertilizer as designed. When the amount of the alkaline water-soluble polymer in the second coating layer is less than the above range, the elution rate of the fertilizer component of the coated granular fertilizer is extremely slow or the fertilizer component does not elute at all.

The coating amount of the second coating layer is preferably 2 to 50% by weight, more preferably 4 to 20% by weight based on the amount of the granular fertilizer. When the coating amount of the second coating layer is less than the above range, it becomes difficult to control the coating amount of the second coating layer according to the design value when the coated granular fertilizer is manufactured (the coating amount of the second coating layer is small. The tolerance of the error becomes narrower), the mechanical strength of the second coating layer decreases, and the second coating layer may be damaged during handling, transportation, or storage of the coated granular fertilizer, and the above-mentioned problems may occur. is there. Further, when the coating amount of the second coating layer is larger than the above range, the elution control effect is not further improved, the content rate of the fertilizer component in the coated granular fertilizer is relatively decreased, and further, the fertilizer component is The amount of coating remaining in the soil after elution increases.

[0013]

INDUSTRIAL APPLICABILITY The coated granular fertilizer of the present invention can be adjusted at any time to start the elution of the fertilizer component in the water-containing medium or water by adjusting the coating. In addition, there is no peeling between the fertilizer and the film, no damage during transportation and handling, and a product with low tackiness and easy handling can be obtained. In addition, since the coating is a propylene-based low molecular weight material, the coating that becomes unnecessary after fertilization has an advantage that it is easily decomposed by light or heat.

[0014]

EXAMPLES The present invention will be described in detail below with reference to examples.

(A) Preparation of First Film Forming Solution 44 g of calcium hydroxide and 6.6 g of EVA (Z289, manufactured by Ube Industries, Ltd.) as an adhesive agent were added to 110 parts of toluene.
It was added to g to disperse and dissolve to prepare a first film-forming solution. (B) The first coating is formed on the surface of the granular fertilizer. Stainless steel tilt control granulator with rotation control (diameter 600 m
m, depth 150 mm) and granular urea 2 to 4 mm in particle size 2,
000 g was added, the granulator was rotated at a rotation speed of 15 rpm, and while blowing hot air at about 40 ° C., the above first film-forming solution was added little by little over 20 minutes to the surface of the granular urea. A first coating was formed. (C) Urea elution test method 5.31 elution rate (of coated fertilizer) in the fertilizer analysis method published by the Ministry of Agriculture, Forestry and Fisheries, National Institute for Agro-Environmental Technology (December 25, 1987)
A dissolution test was performed according to the test method. However, the measurement temperature (temperature of the incubator) was changed to 25 ± 1 ° C. (D) Degradability of coated granular fertilizer [weather resistance test] 100 g of coated granular fertilizer according to JIS A1415
Was exposed for 1500 hours at a black panel temperature of 63 ° C. using a sunshine weather meter (manufactured by Suga Test Instruments Co., Ltd.). Then, the compressive strength of the coated fertilizer grains was measured to determine the retention rate of the initial strength.

Example 1 As a film-forming solution, 35 g of amorphous polyolefin (UT2180 manufactured by Ube Lexen) was added to 403 g of toluene.
It was prepared by dissolving at 5 to 105 ° C. This film forming solution was used at the temperature of 100 ± 5 ° C. to form a film.
400 g of granular urea (without the first coating) was put into a vacuum aeration type coating device (Freund Industrial Co., Ltd., coating device Hicoater Mini, coating pan capacity 0.65 liter), and the coating pan was rotated at 30 rpm. The above film-forming solution was sprayed at a supply rate of 10 ml / min while being swirled at a speed and sucking warm air of about 40 ° C.,
A single layer coated granular fertilizer was produced by forming a coating on the surface of granular urea. The amount of coating of the obtained single-layer coated granular fertilizer was urea 1
It was 8.3 parts by weight per 00 parts by weight. A urea elution test was performed on the produced single-layer coated granular fertilizer, and the obtained results are shown in FIG.

As a result of the test by the method (D), the compressive strength was 0.1 kg / grain and the retention rate was 3%. In addition, the appearance is almost grainy with cracks on the entire surface.

Example 2 As a second film forming solution, 35 g of amorphous polyolefin (UT2180 manufactured by Ube Lexen) was added and 403 g of toluene.
It was prepared by dissolving it at 95 to 105 ° C. Granular urea (400 g of urea, 9.4 g of coating material) having the first coating treated with (B) was put into the coating apparatus used in Example 1 to form the first coating under the same conditions as in Example 1. A second coating was formed on the surface of granular urea to produce a coated granular fertilizer.
The amount of the first coating of the obtained coated granular fertilizer was 2.35 parts by weight per 100 parts by weight of urea, and the amount of the second coating was 1 part by weight of urea.
It was 8.3 parts by weight per 00 parts by weight. The coated granular fertilizer produced was subjected to a dissolution test by the method shown in (C), and the obtained results are shown in FIG.

Example 3 To prepare the second film-forming solution, the materials shown below were mixed with toluene 5
It adjusted by melt | dissolving in 34 g (100-110 degreeC). (A) Amorphous polyolefin (manufactured by Ube Lexen Co., Ltd .:
UT2180) 20 g (43.1% in composition) (b) EPR (JSR-EP912P) 12 g (25.9% in composition) (c) WAX (manufactured by Chusei Wax: Polyletts-2)
00) 8 g (17.2% in the composition) (d) SMA (styrene / maleic anhydride resin, alkaline water-soluble polymer) (Kuraray SMA-3000) 6.
4 g (13.8% in composition) A coated granular fertilizer was produced in the same manner as in Example 2 except that the second coating was adjusted. The amount of the first coating of the obtained coated granular fertilizer was 2.35 parts by weight per 100 parts by weight of urea, and the amount of the second coating was 11 parts by weight per 100 parts by weight of urea. The combined weight ratio is 13
It was 1/100. Regarding the obtained coated granular fertilizer,
The dissolution test was carried out by the method shown in (C), and the obtained results are shown in FIG.

Example 4 In the composition of the second coating material shown in Example 3, SMA3,
The amount of 000 resin used is 9.6g, and the amount of toluene used is 57
A coated granular fertilizer was produced in the same manner as in Example 1 except that the amount was changed to 0 g, and tested by the method (C). The amount of the first coating of the obtained coated granular fertilizer was 2.35 parts by weight per 100 parts by weight of urea, and the amount of the second coating was 11.8 parts by weight per 100 parts by weight of urea.
Parts by weight, and the weight ratio of the alkali substance / alkali water-soluble polymer was 89/100. The results are shown in FIG.

Example 5 In the composition of the second coating material shown in Example 3, SMA3,
2,000 resin usage 12.8g, toluene usage 6
A coated granular fertilizer was produced in the same manner as in Example 1 except that the amount was changed to 07 g, and was tested by the method (C). The amount of the first coating of the obtained coated granular fertilizer was 2.35 per 100 parts by weight of urea.
Parts by weight, the amount of the second coating is 12. per 100 parts by weight of urea.
It was 7 parts by weight, and the weight ratio of the alkaline substance / alkali water-soluble polymer was 66/100. This result is the first
Shown in the figure.

Comparative Example 1 As a film forming solution, the content of ethyl acrylate unit was 8
Ethylene with a mol% of 13 and a melt index (MI) of −
Ethyl acrylate copolymer (manufactured by Nippon Conika Co., Ltd.,
Product name DPDJ-8026) 35 g of resin, toluene 4
It adjusted by making it melt | dissolve in 03g at 95-105 degreeC. This film forming solution was used at the temperature of 100 ± 5 ° C. to form a film. 400 g of granular urea (without the first coating) was introduced into the coating apparatus used for forming the second coating in Example 1, the coating pan was rolled at a rotation speed of 30 rpm, and warm air of about 40 ° C. was applied. While aspirating, the above film-forming solution was sprayed at a feed rate of 10 ml / min to form a film on the surface of the granular urea to produce a single-layer coated granular fertilizer.
The amount of the coating of the obtained single-layer coated granular fertilizer was 8.3 parts by weight per 100 parts by weight of urea. A urea elution test was performed on the produced single-layer coated granular fertilizer, and the obtained results are shown in FIG.

Comparative Example 2 As a film forming solution, EPR (JSR-EP91) was used instead of the ethylene-ethyl acrylate copolymer of Comparative Example 1.
A coated granular fertilizer was produced in the same manner as in Comparative Example 1 except that 2P) was used. The amount of the coating of the obtained single-layer coated granular fertilizer was 8.3 parts by weight per 100 parts by weight of urea.
The produced single layer coated granular fertilizer was subjected to a dissolution test by the method shown in (C), and the obtained results are shown in FIG.
As a result of the test by the method (D), the compressive strength was 2 kg / grain and the retention rate was 50%. This indicates that the EPR system is inferior in deterioration disintegration property.

[Procedure amendment]

[Submission date] December 15, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 Cumulative dissolution rate (%) and number of days of dissolution according to an example of the present invention
It is a figure which shows the relationship with (week).

FIG. 2 Cumulative dissolution rate (%) and number of days of dissolution of the comparative example of the present invention
It is a figure which shows the relationship with (week).

[Explanation of symbols] 1 Example 1 2 Example 2 3 Example 3 4 Example 4 5 Example 5 6 Comparative Example 6 7 Comparative Example 7

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 2

[Correction method] Change

[Correction content]

[Fig. 2]

Claims (4)

[Claims] 1. A coated granular fertilizer characterized in that the surface of the granular fertilizer is coated with a film containing an amorphous polyolefin obtained by copolymerizing propylene and ethylene and / or butene-1 as a main component. 2. A coating comprising a first coating made of an alkaline substance on the surface of granular fertilizer, and a main component of which is an amorphous polyolefin obtained by copolymerizing propylene and ethylene and / or butene-1 on the surface of the coating. A coated granular fertilizer characterized by coating. 3. The coated granular fertilizer according to claim 1, wherein the constituent components of the amorphous polyolefin are 0 to 20% by weight of ethylene, 1 to 70% by weight of butene-1, and the balance is propylene. 4. The coated granular fertilizer according to claim 1, 2, or 3, wherein the amorphous polyolefin has a number average molecular weight of 1,000 to 20,000.