JPH0346430B2 - - Google Patents

Description

[Detailed description of the invention]

Industrial Application Field The present invention provides a slow-release coated fertilizer and is useful in the field of fertilizer industry. Prior Art Generally, chemical fertilizers are fast-acting, and it is difficult to maintain their effect over a long period of time. Furthermore, if a large amount of fertilizer is applied at once, there is a risk of damage to the salinity of agricultural crops and pollution of rivers due to fertilizer leaching. As a means to improve the above points, slow-release fertilizers coated with various resins have been proposed. When attempting to produce a slow-release coated fertilizer using a spray coating method, the following coating resin systems are generally considered. (1) Resin solution dissolved in organic solvent (2) Aqueous solution of water-soluble resin (3) Aqueous emulsion of resin Problems to be solved by the invention When producing coated fertilizer using the above resin system, various problems arise. A point exists. In the case of (1), raw material costs are high because organic solvents are used. There is also the risk of air pollution and fire during manufacturing. In the case of solvent recovery, equipment is required, which significantly increases equipment costs. In the case of (2), since the resin is water-soluble, there is a limit to its ability as a protective film to essentially increase the elution rate and slow the effect of fertilizer components. Case (3) does not have the problems of (1) and (2), but includes the following drawbacks due to the conventional aqueous emulsion-based coating material, that is, thermoplasticity and dispersion. Formation of a continuous film A water-based resin emulsion consists of fine resin particles dispersed in water. In order to achieve sustained release of fertilizer components, it is necessary to cover the fertilizer with a uniform film. For this purpose, individual emulsion particles must be fused together to form a continuous film. Consolidation of Coated Fertilizer If the resin is thermoplastic, when temperature or load is applied, such as when fertilizers are piled up in bags in the summer, the coated fertilizer will fuse together on the surface of the coating film and solidify. In order to prevent the coated fertilizer from caking together, a resin system with a high softening temperature can be selected, but on the contrary, this resin system makes it difficult to form a continuous film, resulting in a decrease in sustained release properties. On the other hand, when attempting to improve sustained release by lowering the glass transition temperature of the resin or adding film-forming aids or plasticizers to facilitate the formation of a continuous film, the coating film softens and melts. This makes it easier for fertilizers to clump together. As described above, it has been difficult to form a uniform continuous film, maintain excellent sustained release properties, and prevent the coated fertilizer from caking together. Means to Solve the Problems As a result of intensive studies to solve these problems, we have found that the above problems can be solved by using melamine resin in combination with an aqueous emulsion of thermoplastic resin and heat-treating it at a temperature of 70°C or higher. It became clear,
The present invention has now been completed. The present invention will be explained in detail below. The present invention provides a slow-release coated fertilizer obtained by coating a solid fertilizer with a coating material mainly composed of an aqueous emulsion of a plastic resin and a melamine resin, and then heat-treating the fertilizer at a temperature of 70°C or higher. The slow-release coated fertilizer of the present invention is produced by spraying the coating material onto the solid fertilizer using a generally used fluidized bed coating device, rotating drum coating device, etc., and then heat-treating the solid fertilizer at a temperature of 70°C or higher. It can be manufactured by As the solid fertilizer, any powder, granule, or granule that can be coated with resin can be used. As the thermoplastic aqueous emulsion in the present invention, a single or copolymer emulsion obtained by polymerizing one or more of the following monomers, or a mixture of two or more aqueous emulsions is used. be able to. (1) Aromatic vinyl compounds represented by styrene (2) Unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, fumaric acid, and itaconic acid,
Neutralized salts thereof and esters thereof. (3) Unsaturated carboxylic acid esters of alcohols further containing functional groups such as glycidyl methacrylate, 2-hydroxyethyl acrylate and 2-hydroxypropyl acrylate. (4) Vinyl carboxylic acid esters represented by vinyl acetate. (5) Vinyl cyanide compounds represented by acrylonitrile. (6) Vinylamide compounds represented by acrylamide and methacrylamide. (7) Aliphatic diene represented by butadiene. (8) Olefin compounds such as ethylene and propylene diisobutylene. (9) Halogen-substituted vinyl compounds represented by vinyl chloride and vinylidene chloride. (10) Di- and trivinyl compounds such as divinylbenzene, 1,4-butanediol diacrylate, trimethylol, propane triacrylate. When producing an aqueous emulsion, thermal decomposition initiators such as persulfates, persulfates, etc. are used as polymerization initiators.
Ferrous, hydrogen peroxide-ferrous Fenton reagents,
Redox type initiators such as persulfate-sodium thiosulfate type, persulfate-acidic sodium sulfite type, and hydrogen peroxide-oxycarboxylic acid type can be used. Further, as the emulsifier, ordinary polymer emulsifiers and low-molecular emulsifiers can be used, but they exhibit particularly effective performance when used in combination. Polymer emulsifiers include water-soluble alkyd resins, and low-molecular emulsifiers include fatty acid salts, higher alcohol sulfates, anionic emulsifiers such as alkylaryl sulfonates, polyoxyethylene alkyl ethers, and polyoxyethylene alkyl phenol ethers. Nonionic emulsifiers such as polyoxyethylene alkyl esters and polyoxyethylene alkyl esters can be used. The amount of coating resin is preferably 2 to 15% by weight based on the fertilizer. If the amount is less than this, a sufficient coating effect cannot be obtained and sustained release properties are not good. If the amount is too large, the price will be high and the proportion of the coating material in the coated fertilizer will increase, making it impractical. As the melamine resin, various melamine resins such as methylated melamine resin, butylated melamine resin, and melamine-urea cocondensation resin can be used. For example, Nikaratsuk MW−12, 22,
30, 40 (Sanwa Chemical Co., Ltd.), Sumamil M-
50W, 40W, 30W; M-100; DM101 (Sumitomo Chemical
Co., Ltd.), Sumillaz Resin 613 (Sumitomo Chemical Co., Ltd.), Cymel 300, 301, 303, (American Cyanamid Company), etc. The amount of melamine resin used is preferably in the range of 2 to 35% by weight based on the solid content of the emulsion resin.
If the amount is less than this, the effect of preventing caking of the coating material due to crosslinking reaction will be reduced. Also, if it is more than this,
Conversely, the amount of unreacted melamine resin increases, which has a negative effect on sustained release. In order to improve the film-forming properties of the emulsion particles, film-forming aids or plasticizers can be used in combination with these systems, if necessary. As the film-forming aid or plasticizer, commonly used film-forming aids or plasticizers can be used, specifically butyl carbitol, butyl cellosolve, phenyl cellosolve, hexyl cellosolve, octyl cellosolve, dibutyl phthalate, Examples include dioctyl phthalate, butyl carbitol acetate, xylene, benzyl alcohol, hexylene glycol, and the like. The optimum amount of the film-forming aid or plasticizer to be used varies depending on the glass transition temperature of the resin emulsion used, but it is generally preferably 2 to 30% by weight based on the resin solid content. If the amount is too small, the resin with poor film-forming properties will not be able to promote the formation of a sufficient continuous film, and sustained release properties will not be improved. If the amount is too high, the coating treatment temperature will be lowered, the coating treatment properties will be poor, and the resulting coated fertilizer will be likely to solidify. Furthermore, it is expensive and not common. In order to achieve both sustained release properties and prevention of caking in the thus obtained coated fertilizer, the crosslinking reaction of the melamine resin must proceed by heat treatment. For this reason, higher temperature and longer heat treatment conditions are preferred, but generally 70 to 120℃.
Processing conditions of 30-60 minutes are suitable. During the heat treatment process, the coated fertilizer may solidify in the process of raising the temperature to 70°C if the resin system has a low softening temperature. In order to avoid this, it is preferable to treat the coated fertilizer with a fine powder of Aerosil, talc, etc. after the coating is completed, and after allowing the coated fertilizer to adhere to the surface of the fertilizer, heat treatment is performed by raising the temperature. Note that the elution rate of the fertilizing ingredients can be adjusted by changing the coverage rate. It is also possible to adjust the elution rate of fertilizing ingredients by changing the type of monomers constituting the aqueous emulsion of thermoplastic resin or by selecting a combination of two or more types of aqueous emulsions. be. The present invention will be explained below with reference to Examples. The aqueous resin emulsions used in the examples are as follows.

[Table] Charge the emulsifiers Hopezol GI-4, Nitsusan Nurex R and water into a reactor and stir under a nitrogen stream. When the temperature was raised to 80℃, the monomer concentration of 10
Add % amount %. Next, 90% of the aqueous solution of ammonium persulfate as a polymerization initiator is added. After a while, begin adding the remaining monomer. After about 3 hours, the addition of the remaining polymerization initiator was added and the aging was continued for 1 hour.
Do time. The reaction temperature is kept constant at approximately 80°C. After the reaction was completed, it was cooled, neutralized with aqueous ammonia, and filtered through cloth. The glass transition temperature is a value measured using a DSC measuring device manufactured by Seiko Electronics Co., Ltd. at a heating rate of 10° C./min. The method of the present invention can be used for various solid fertilizers such as powder, granules, and granules, but is particularly suitable for granular fertilizers. As a granular fertilizer,
Phosphorous Salt Akari No. 1 (manufactured by Asahi Kasei Industries), Shioka Rinkan No. 1, Advanced Chemical Fertilizer No. 777 (manufactured by Nippon Kagaku Co., Ltd.),
Examples include KH 12-8-10 (manufactured by Kyowa Hakko Kogyo Co., Ltd.). In the examples, KH12-8-10 was used. In Examples, coated fertilizers of the present invention were manufactured using the coating apparatus shown in FIG. Examples and comparative examples of the present invention will be shown below. Example 1 Aqueous emulsion A (solid content: 40%) 25 parts by weight Film forming aid, butyl carbitol 2.8 parts by weight Melamine resin: Sumimaru M-30W (melamine/formalhyde/methanol polycondensate) Sumitomo Chemical Co., Ltd. )
100 parts by weight of granular fertilizer was coated with 1.3 parts by weight of water and 10.9 parts by weight of the coating material at about 80°C, and after the coating was completed, the temperature was raised and dried at 100°C for 1 hour. Example 2 Aqueous emulsion B (solid content: 40%) 25 parts by weight Film forming aid, butyl carbitol 1.4 parts by weight Melamine resin: Sumimaru M-30W (melamine/formalhide/methanol polycondensate)
1.3 parts by weight of water and 12.3 parts by weight of the coating material were coated on 100 parts by weight of granular fertilizer at approximately 43°C. After coating, 0.1 parts by weight of talc was added and the fertilizer was sprinkled with powder, and the temperature was raised to 100°C. It was dried for 1 hour. Example 3 Aqueous emulsion C (solid content: 40%)
13.7 parts by weight Aqueous emulsion of styrene-butadiene copolymer JSR-0592: Japan Synthetic Rubber Co., Ltd. (solid content:
(adjusted to 40%) 11.3 parts by weight Film forming aid, butyl carbitol 0.8 parts by weight Melamine resin: Sumimaru M-30W (melamine/formalhide/methanol polycondensate)
100 parts by weight of granular fertilizer was coated with 1.3 parts by weight of water and 12.9 parts by weight of the coating material at about 80°C, and after the coating was completed, the temperature was raised and dried at 100°C for 1 hour. Comparative Example 1 Aqueous emulsion A (solid content: 40%) 25 parts by weight film-forming aid, butyl carbitol 2.8 parts water 12.2 parts by weight of the coating material was coated on 100 parts by weight of granular fertilizer at about 80°C. Comparative example 2 Aqueous emulsion B (solid content: 40%)
100 parts by weight of granular fertilizer was coated with a coating material containing 25 parts by weight of film-forming aid, 1.4 parts by weight of butyl carbitol, and 13.6 parts by weight of water at about 43°C. The coated granular fertilizers of Examples 1 to 3 had a load of 250 kg/
cm ² , and no caking occurred even after being left at 60°C for one day. In Comparative Example 1, light caking occurred under the same conditions,
In Comparative Example 2, caking occurred even at room temperature. The sustained release properties are shown in Figure 2. Figure 2 shows that 10g of the coated fertilizer obtained in the example was added to water at a temperature of 30°C.
The elution rate of ammonia nitrogen when immersed in 200ml of each coated fertilizer is shown. Effects of the Invention By using the method of the present invention, a melamine resin is used in combination with an aqueous emulsion of a thermoplastic resin, and heat treatment is performed at 70°C or higher. It is possible to obtain a slow-release coated fertilizer that has a property of setting. In addition, a water-based emulsion of a general-purpose resin can be used, and it can be manufactured at a low cost. Furthermore, the coated fertilizer has a glossy appearance, is very beautiful to look at, and has a high commercial value.

[Brief explanation of drawings]

FIG. 1 shows a schematic diagram of a fluidized bed coating apparatus. FIG. 2 shows the elution rate of the coated fertilizer obtained in the example. In the figure, Example-1, Example-2, Example-3, Ratio-1, and Ratio-2 indicate Example 1, Example 2, Example 3, Comparative Example 1, and Comparative Example 2.

Claims (1)

[Claims] 1. A slow-release coated fertilizer obtained by covering a solid fertilizer with a coating material whose main components are an aqueous emulsion of a thermoplastic resin and a melamine resin, and then heat-treating it at 70°C or higher.