KR880000153B1 - Making method of fertilisers - Google Patents

Abstract

The double coatings of fertilizers (FZ) are made up of (i) 1st layer coating : 1-10 wt.% of silicates i.e. Na, Li, Etsilicate to 100wt.% FZ and (ii) 2nd layer coating: 1-10 wt.% of high mol. latexes i.e. natural latex, stylene-butadien copolymer latex to 100wt.% 1st layered FZ. Silicate aq. soln. (25-30 wt.%) is coated onto FZ at the supply rate (SR) of 2-20 ml/min with supply nozzle pressure (SNP) of 0.2-5 kg/cm2 and hot blast (HB) of 20-100 deg.C to 500kg of FZ. High mol. latex aq. soln. (10-15 wt.%) is coated onto 1st layer at half the SR of silicate with SNP of 0.1kg/cm2 and HB of 20-60 deg.C.

Description

Process for preparing long-lasting granular fertilizer double coated with silicate-polymer latex

1 (a) is a schematic cross-sectional view of the granular fertilizer coated by the method of the present invention,

1 (b) is a partially enlarged cross-sectional view of FIG.

Fig. 2 (a), Fig. 2 (b), Fig. 2 (c) and Fig. 2 (d) are schematic diagrams showing the formation process of the coated film according to the method of the present invention, respectively. 2 (b) and 2 (c) show a process in which polymer particles of latex form a dense film as water evaporates, and FIG. 2 (d) shows a boundary between dense latex particles after being sufficiently dried. It is a schematic diagram showing the missing state,

3 is a schematic diagram of a fluidized bed coating apparatus used for coating fertilizer particles in the present invention.

The present invention relates to a sustained granular fertilizer double coated with silicate-polymer latex, to be described in more detail, a primary coating of silicate on granular fertilizer to form a uniform smooth base coating, followed by a secondary coating with a water dispersible emulsion-type latex on the base coating. The present invention relates to a new method for producing a long-acting fertilizer, in which a film which does not pass water well is made to remarkably relax the water dissolution rate of the fertilizer component so that the long term ineffectiveness can be maintained even with a single fertilization.

With the development of agricultural technology today, which promotes the mechanization of farming, a single fertilization can provide a continuous supply of fertilizer components throughout the entire growth period of the crop, which not only significantly reduces labor costs but also fertilized fertilizers. There is an urgent need for the development of sustainable fertilizers that can reduce the loss of nutrients. There are many different types of sustainable fertilizers that have been developed and marketed. There are three general types of these conventional sustainable fertilizers. In other words,

1) A chemical reaction type in which the fertilizer component is chemically reacted with other substances so that the fertilizer component is slowly decomposed and released after fertilization.

2) a physically mixed form in which the fertilizer component is physically mixed with other substances, and then the fertilizer component is slowly eluted through the tissue of the particles, and

3) There is a coating type in which the surface of the fertilizer particles is coated with a thin film so that the fertilizer component is gradually diffused through the film.

Representative examples of persistent fertilizers belonging to chemical reactions are those described in US Pat. Nos. 2,592,809 and 3,322,528, which suggest that the fertilizers proposed in these patents are difficult to manufacture and of high quality. There is a problem that it is difficult to obtain uniformity and the price of the product is expensive.

Examples of the persistent fertilizers belonging to the physical-type mixed type include those described in Japanese Patent Publication Nos. 49-41, 150 and 49-24, 752. While these fertilizers have the advantage of being easy to manufacture, they are unnecessary. It is accompanied by a relative decrease in the content of the fertilizer component by mixing with the foreign matter, and thus there is a problem of the price increase of the product relative to the amount of the active ingredient of the fertilizer, it is not widely used.

, 미국 특허 제3, 223, 518호가 있는데, 이것은 디시클로펜타디엔 글리세롤 에스테르의 공중합 물질을 주성분으로 하여 요소 입자를 복수층으로 피복한 것으로서, 그 제품의 성질은 양호하다. 그러나, 특수한 고분자 물질을 사용하여야 하므로, 피복 물질의 가격이 비싸고 복수층 피복을 거쳐야 하기 때문에 제품의 가격이 높다는 결점이 있다. 그보다 중요한 결점으로서는 피복 공정에 사용되는 유기 용매의 회수 작업이 복잡하고 어렵기 때문에, 미회수 용매로 인한 제품 가격의 상승 및 환경 오염 문제를 유발시킬 우려가 높다는 점이다. 한편, 일본국의 짓소 아사히 히료오 가부시끼가이샤(Chisso Asahi Rertilizer K. K.)의 뉴트리코트 (Nutricote

, 대한민국 특허 공고 제82-2204호)는 올레핀계 고분자를 고온의 유기 용매에 용해시킨 용액을 비료 입자에 분무하여 피복시킨 비료인데, 이 제품도 역시 사용된 유기 용매의 회수에 어려움이 있다. 또한, 미국의 테네시 협곡청(T.V.A.)에서 개발한 황 피복 요소(Sulfur Coated Urea : SCU)는 예열된 요소 입자 위에 용융 상태의 황을 분무한 다음에 왁스류의 밀봉제로 황에 발생된 균열들을 메워서 완성한 제품이다. 이 제품은 피복 재료로서 값싼 황을 사용하였으므로 제품 가격이 저렴한 장점은 있으나, 밀봉제로 사용한 왁스가 토양 중의 미생물에 의하여 분해되므로, 그에 따라 비료의 용출 속도가 빨라지고, 토양중에 황이 축적되어 토양의 산성화가 촉진되는 문제점이 있다.On the other hand, the sustainable fertilizers belonging to the coating type can obtain a sufficient sustaining effect even if a small amount of coating material is used, and the dissolution rate of the fertilizer can be easily controlled by the thickness of the coating and the incorporation of appropriate additives in the coating and post-treatment thereof. It can be said that it is the type of fertilizer that is the most active research and development. An example of this class of fertilizer is Osmocote developed by the Archer Daniels Midland Company of the United States.

, US Patent No. 3, 223, 518, which is a coating of urea particles in multiple layers with a copolymer of dicyclopentadiene glycerol ester as a main component, and the properties of the product are good. However, there is a drawback that the price of the product is high because of the high cost of the coating material and the multi-layer coating because of the use of a special polymer material. A more important drawback is that the recovery of the organic solvents used in the coating process is complicated and difficult, so that there is a high possibility of causing rises in product prices and environmental pollution due to unrecovered solvents. On the other hand, Nutricoat of Chisoso Asahi Rertilizer KK of Japan

, Korean Patent Publication No. 82-2204) is a fertilizer coated by spraying a solution of an olefinic polymer in a high temperature organic solvent by spraying on a fertilizer particle, which also has a difficulty in recovering the used organic solvent. In addition, Sulfur Coated Urea (SCU), developed by the Tennessee Canyon, USA, sprays molten sulfur over the preheated urea particles and then fills the cracks in the sulfur with wax sealants. It is a finished product. This product has the advantage of low cost because it uses cheap sulfur as a coating material, but the wax used as the sealant is decomposed by microorganisms in the soil, so that the fertilizer dissolution rate is accelerated and sulfur accumulates in the soil and acidification of the soil is achieved. There is a problem that is facilitated.

As described above, the common problems of the coated sustainable fertilizer developed so far can be summarized as follows. In other words,

1) Since the coating material used is mainly a polymer material, it is inevitable to use an expensive organic solvent that will dissolve the polymer material in order to obtain the form required for spraying at the time of coating, and thus a solvent recovery process must be added. There is a factor in the cost increase.

2) In some cases, there is a fear that the fertilizer component is dissolved in the solvent and the fertilizer particles decompose during the coating.

3) After the coating process is completed, harmful organic solvents are likely to remain in the fertilizer, which may lead to environmental pollution.

4) Since the surface of the rough (rugged) fertilizer must be filled with expensive polymeric materials, the amount of coating is increased so much that waste of coating materials is severe.

Furthermore, it is known that the polymer coating fertilizer is a better product than the sulfur coating fertilizer among the existing coating fertilizers, but in order to obtain this, the polymer material must first be dissolved in an organic solvent and sprayed onto the fertilizer particles, so that after coating There are drawbacks to recovering the organic solvent. Since the problem of how much organic solvent can be recovered plays an important role in the reduction of manufacturing cost, if there is a way to coat the fertilizer particles without using organic solvent, there is a better way. There will be no. As a method of not using an organic solvent, there is a method of coating the fertilizer by directly melting the polymer material and spraying it onto the fertilizer (eg, urea fertilizer) particles, but the polymer material has a high viscosity even at a high temperature of about 200 ° C. In view of the fact that it is not easy to spray it on the surface of the fertilizer and that the melting temperature of the urea is 132.7 ° C., the coating of the urea particles becomes difficult at higher temperatures. These problems are the problems to be solved in the present invention.

Therefore, the present inventors first smoothly coat the surface of the fertilizer particles by using a water-soluble inexpensive silicate aqueous solution as the base coating material, and then further coat the silicate coating layer with a water-dispersible emulsion type latex, thereby covering the aforementioned conventional coating. Based on the idea of obtaining a sustainable fertilizer that solves all the problems of the mold fertilizer, the present invention has led to a long-term study.

It is an object of the present invention to propose a new method for producing fertilizers having excellent coating properties and thus excellent durability, without inherently dissolving the polymer coating material in an organic solvent or melting at high temperature.

The present invention and its effects and effects are sprayed with 10-38% by weight aqueous silicate solution on the surface of the fertilizer particles to obtain a silicate coating layer after drying, followed by 5-20% by weight of polymer latex on the silicate coating layer surface. Spraying an aqueous solution to further form a latex coating layer.

According to the present invention, a primary coating layer coated with 1-10 parts by weight of silicate based on 100 parts by weight of fertilizer particles to be coated, and a secondary coating layer coated with 1-10 parts by weight of polymer latex with respect to 100 parts by weight of fertilizer particles to be coated are It can be integrally formed on the primary coating layer.

Again, in the present invention, the first consideration in the selection of the coating material is its importance in selecting a coating material using water as a solvent.

Therefore, in the present invention, first, the surface of the fertilizer particles is smoothed (smooth), and at the same time, in order to prevent the water or other foreign substances contained in the solvent from penetrating into the fertilizer particles. The primary coating is performed by spraying the silicate with excellent coating properties onto the surface of the fertilizer particles. Particularly suitable silicates for the purposes of the present invention include sodium silicate, and lithium silicate, potassium silicate and ethyl silicate may also be used. Generally, silicate is water-soluble, but it does not cause the particles to stick together even under high temperature dry hot air, so it is possible to instantaneously coat the surface of fertilizer particles, and there is a big difference between the strength of the fertilizer particles after coating and the strength before coating. none. Moreover, since the said silicate has good adhesiveness, even the fertilizer particle with a rough surface can form a smooth film like the glass surface without a flaw on the whole surface. Thus, the following problem can be solved by filling the rough surface of a fertilizer with an aqueous silicate solution. In other words,

1) Due to the good adhesion of the silicate, even if the surface of the fertilizer particles irregular shape, a uniform film without scratches can be obtained.

2) Since the solvent is water, no organic solvent recovery process as in the polymer coating method is involved.

3) It is not decomposed by microorganisms in soil.

4) Since the polymer film can be easily secondary coated with a certain thickness directly on it, the amount of polymer coating can be reduced.

5) It is cheaper than polymer material.

In the process of the present invention, it is possible to obtain a fertilizer product in which the fertilizer component can be continuously eluted out for a longer period of time, such as for 100 to 150 days, by further coating the polymeric material on the primary silicate coating. Here too, it is also important that the secondary coating polymer material should be one capable of using water as a solvent.

Representative examples of so-called water-soluble high molecular materials include polyvinyl alcohol, carboxymethyl cellulose, and the like, but when these are used as secondary coating materials of the present invention, the particles are entangled with each other during coating, and coating is impossible.

Therefore, the present invention adopts a method using a so-called water dispersible emulsion type latex in which fine particles of the polymer are dispersed in water. In other words, spherical fertilizer particles can be sprayed with latex to evaporate the solvent to form a polymer film, which is an existing polymer coating method using a polymer material dissolved in an organic solvent (for example, Korean Patent Publication No. 79-898). And 82-2204). The present inventors first examined whether the coating fertilizer could be produced by latex alone without silicate-based coating. When the latex is directly sprayed onto the fertilizer and coated, if the temperature of the dry hot air used is too high (above 60 ° C), most of the latex becomes sticky and the fertilizer particles stick to each other, making the coating impossible. In order to prevent the stickiness of latex, lowering the temperature of the drying component does not completely evaporate water, penetrates into the fertilizer particles, weakens the fertilizer strength, and tends to cause the fertilizer to break down during storage. Accordingly, it has been found that there is a technically significant problem when only latex is applied to fertilizer particles alone without a base coating. However, it has been found that when latex coating is carried out on the base coating of fertilizer particles with silicate as in the present invention, coating can be excellent even under low temperature dry hot air. This is because the silicate-based coating acts as a barrier against the infiltration of fertilizer particles into water that failed to evaporate during latex coating.

In this way, after the silicate base coating, various polymer latex coatings can be applied thereon. Therefore, various polymer latexes can be arbitrarily used as secondary coating agents depending on the properties of the desired persistent fertilizer. In particular, if several latexes are mixed instead of using a single type of polymer latex, the heat resistance, impact resistance, weather resistance and dissolution rate of the persistent fertilizer can be arbitrarily changed, so that the polymer is dissolved in an organic solvent and sprayed. As a result, a wider variety of products can be obtained than conventional methods of coating.

For example, in the case of NUTRICOT (Korean Patent Publication No. 82-2204), an appropriate amount of talc powder is included in the coating to control the dissolution rate of fertilizer in water, and the inorganic material talc is well dispersed in the polymer solution. There is a problem that does not, and in the case of sulfur coating element (SCU) to control the dissolution rate by changing the coating amount, there is a problem that the content of the fertilizer changes depending on the product. However, in the case of the present invention, it is advantageous to obtain various products with different dissolution rates by coating various latexes that are mixed well with each other while maintaining a constant coating amount. Again, the advantages of such latex coatings can also be obtained without the basic coating using silicate as suggested in the present invention, and therefore, the present invention is characterized in this respect. The latex that can be used for this coating can be used in principle of any type of latex, but in particular, the following lists the preferred polymer latex having a low stickiness at the time of coating or low water permeability of the coating. That is, natural latex, styrene-butadiene copolymer latex, butadiene copolymer latex, styrene-2-ethylhexyl acrylate-acrylonitrile copolymer latex, acrylonitrile acrylic polymer latex, chloroprene polymer latex, vinyl acetate polymer Latex, isoprene-based polymer latex, vinyl chloride-based polymer latex, vinylidene chloride-based polymer latex, and the like. These compounds may be used alone or in combination of two or more. In addition, a curing agent may be added to improve polymer properties. "Latex" refers to the dispersion of the polymer material in the colloidal form on the aqueous solution, the method for producing a fertilizer having a sustained by spraying and coating on the fertilizer particles using such a latex can not go beyond the scope of the present invention.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1 (a) and 1 (b) show the cross-sectional structure of the persistent fertilizer in which the silicate layer (S) and the polymer latex layer (L) are integrally coated on the fertilizer particles (F) by the method of the present invention. Is typically well represented.

2 (a) to 2 (c) illustrate well the process of changing the film into a dense structure after the polymer latex layer L is coated. That is, after forming and drying the silicate layer (S) which is a base film on the fertilizer particle layer (F), spraying and coating predetermined | prescribed latex (L) of the emulsion dispersion state on it, and supplying hot air over the film, time As time passes, moisture evaporates from the colloidal dispersion, and polymer latex particles aggregate with each other to cause densification. Therefore, when all the water is removed in accordance with the continuation of the hot air drying, as shown in FIG. 2 (d), the boundary between the dense latex particle layer and the silicate layer is lost, thereby completing a film in which the two layers are integrally formed. .

The apparatus shown in FIG. 3 is a schematic of a fluidized bed coating apparatus that can be used in the present invention. First, the fertilizer particles 1 to be coated are introduced into the fluidized bed 2. Subsequently, the coating solution supplied from the coating solution container 3 via the feed pump 4 is ejected upwardly into the fluidized bed 2 through the nozzle 5 provided at the bottom of the fluidized bed 2. At the time of supply of this coating solution, compressed air is simultaneously supplied to the nozzle 5 via the pressure regulating valve 6. The supply pressure of the pressure air can be controlled by the pressure gauge 7. At this time, the air introduced through the air inlet 8 is warmed to a predetermined temperature by the heat exchanger 9 and this air is used for flowing the fertilizer particles and at the same time drying the coating solution coated on the fertilizer particles. This fluidized bed coating apparatus can be used for both silicate coating and polymer latex coating, but it is generally preferable to use a separate device for each coating. At the same time, the air introduced into the fluidized bed 2 is exhausted to the outside through the fan 11. Reference numeral 11 is a filtering network for preventing the fertilizer particles 1 from escaping with the doubled air.

The method of coating the coating materials on the fertilizer particles will be discussed in detail below. The silicate is dissolved in water so that its concentration is 10-38% by weight, preferably 25-30% by weight, and then the solution is a fluidized bed coater in which fertilizer particles of 0.3-0.1 cm in diameter are flowing (see FIG. 3). Spray coating on the surface of the fertilizer particles in the process, the process conditions in the case of using a fluidized bed coater, the feed rate of the coating solution is 2-20 ml per minute, preferably when the amount of fertilizer to be coated once, for example 500g Advantageously 5-10ml per minute, air pressure of the air mixing spray nozzle 0.2-5kg / cm ^2, preferably, 0.5-1kg / cm ^2, the temperature of the hot air is to be 20-100 ℃, preferably 60-80 ℃ . The process conditions in the case of using a rotary cylindrical coater are that the feed rate of the coating solution is 100-1000 ml / min, preferably 300-600 ml / min, when the amount of fertilizer to be coated once is 40 kg. The pressure is 0.1-3kg / cm ² , preferably 0.2-0.5kg / cm ² , the temperature of the hot air is 20-100 ° C., preferably 60-80 ° C., and the rotational speed of the drum is 10-20 revolutions per minute, preferably Is 12-15 revolutions per minute, but unlike a fluidized bed coater, a rotating cylindrical coater is capable of both batch and continuous operation. Here, the fixed conditions have a relative influence on each other without being controlled by independent variables. For example, when the temperature of hot air is raised, the concentration of the solution may be lowered. In addition, it is more advantageous for the initial evaporation of the water to make the initial temperature higher and gradually lower than keeping the temperature of the hot air constant during coating.

In this way, the latex coating is performed after the spraying of the silicate solution of a certain amount is finished. It is preferable to blow hot air for about 30 minutes before the latex coating to completely dry the silicate film. The latex solution is 5-20% by weight, preferably 10-15% by weight, and like the silicate coating, any of a fluidized bed coater and a rotating cylinder coater may be used. The coating conditions are similar to those of the silicate, but the feeding rate of the coating solution is half the level of that of the silicate and the temperature of the hot air is preferably 20-60 占 폚, preferably 40-50 占 폚. However, since such conditions vary depending on the type of latex used, an optimal coating condition should be selected according to the latex. The latex coated fertilizer particles are sprayed with inorganic minerals such as talc and kaolin in an amount of 0.1% -2%, preferably 0.5-1% before drying, or multivalent The aqueous solution of the metal salt may also be sanded in an amount of 0.1-2%, preferably 0.5-1%. Moreover, in order to make the formed film complete, you may heat-process for 10 minutes-2 hours, Preferably it is 30 minutes-1 hours at the temperature of 50-100 degreeC, Preferably it is 60-80 degreeC.

As described above, since the product manufactured in the present invention uses a water dispersible emulsion type latex, a device for dissolving the polymer in a solvent, a device for supplying a heated polymer solution, and a device for recovering the evaporated solvent after spraying No need for stocking, the manufacturing process is simple, and the coating formed is uniform and there is no scratch on the surface.

Hereinafter, the present invention will be described in more detail as examples.

Example 1

Coating of silicate solution

A) coating of silicate solution using a fluidized bed coater

500 g of a spherical urea fertilizer with a particle size of 3-5 mm in a batch-type fluidized bed coater (Uni-Glatt, Japan), was fluidized while maintaining the amount of fluidized air at ² m ² / min and the hot air temperature at 70 ° C. Preheated for a minute. After preheating, dilute 65.8 g of a solution of sodium silicate with a weight ratio of silicon oxide / sodium oxide of 3.4 and a solution concentration of 38% to 25% by weight of sodium silicate with water, and flow through the pump at a flow rate of 5 ml / min. It sprayed in at a nozzle pressure of 1.0 kg / cm <^2> while supplying inside, and the hot air of air temperature of 70 degreeC and air volume of 3.2 m <^3> / min was supplied, and spraying, coating, and drying of a solution occurred simultaneously. Upon completion of the coating of sodium silicate, the temperature of the fluidized bed was lowered to 40 ° C. and further dried for 10 minutes in the fluidized state. The coating yield of sodium silicate was 84-86%, with no agglomeration between the particles during coating, and each fertilizer particles were completely covered with a smooth and transparent coating. The following first table compares and summarizes the coating conditions of the same fluidized bed coater suitable for silicate coating for urea and complex fertilizers.

Conditions in parentheses indicate the range of experimental conditions that can be used.

[Table 1]

Silicate Covering Conditions by Fluidized Bed Coater

(Quantity of concrete fertilizer = 500 g)

By spraying and coating a solution of potassium silicate, lithium silicate and ethyl silicate in the conditions shown in Table 1, a uniform coating similar to the sodium silicate coating was obtained so that the coating yield was 83-89%. On the other hand, by the same coating method, the sodium silicate solution in which the weight ratio of silicon oxide / sodium oxide was 3.3, 3.75, and 4.2 was coated, respectively. Among them, when the sodium silicate solution having a weight ratio of 3.75 and .4.2 was coated, fine residues were generated in the coating, and the solution was unstable, making long-term storage difficult. Therefore, it was found that the best results were obtained when the appropriate weight ratio of silicon oxide / sodium oxide was 3.3-3.4.

B) Spherical element with a diameter of 90 cm, a length of 2 m, and a spherical diameter of 3-5 mm are supplied in 40 kg per hour so that the residence time in the coater is 20 minutes. The sodium silicate solution diluted to 25% by weight of sodium silicate was supplied at a total of 400ml / min to 8 nozzles at 50ml / min per nozzle, and the air spray pressure of each nozzle was 0.2kg / cm ² . The spray was applied to the drop fertilizer curtain, and hot air having a temperature of 80 ° C. and a flow rate of 65 m ² / min was supplied to the lower end of the fertilizer curtain through a hot air distributor to simultaneously spray, coat and dry the solution. The fertilizer, which was coated with sodium silicate, was transferred to a secondary cylinder having a diameter of 60 cm and a length of 1 m for 8 revolutions per minute, and further dried for 20 minutes with an air volume of 40 m ³ / min hot air at a temperature of 40 ° C. The coating yield of sodium silicate was 85-95%, which was the same as or higher than that when coated with a fluidized bed coater. On the other hand, the surface state of the coated fertilizer was also kept smooth and transparent as in the case of using a fluidized bed coater.

Example 2

Sheath of latex solution

A) 500 g of spherical urea having a silicate base coating completed in the fluidized bed coater was put into a fluidized bed coater by the method of 1 to coat the ratchet solution using a fluidized bed coater, and the composition was styrene (60 parts) -2-ethylhexyl acrylate (40 ), The latex solution diluted to 10% of the solid resin concentration is slowly stirred and supplied to the fluidized bed at a flow rate of 5 ml per minute and a nozzle air pressure of 1 kg / cm ² , while simultaneously spraying and spraying the air at a temperature of 40 ° C. 3.2 m ² The spraying / coating and drying of the latex solution occurred at the same time by supplying a / min hot air. The latex coating yield of the coated fertilizer was 86-89%, and even if the latex coating amount was more than 15% of the fertilizer weight, it was coated with a uniform polymer film without lumping between particles. The latex-coated fertilizer is transferred to a small rotating cylinder of 25 cm in diameter, 15 cm in length, and 6 revolutions per minute, and the talc powder of about 100 mesh is added together at 0.5-1% of the fertilizer weight for 30 minutes at 75 ° C. The heat treatment increased the density of the film.

B) 40 kg of the spherical element completed in the silicate base coating according to Example 1-b was placed in a cylindrical coater having a diameter of 90 cm, a length of 2 m, and rotating 12 per minute in a cylindrical cylindrical coater, and batchwise. Latex coating was performed. A latex solution of styrene (60 parts) -2-diethylhexyl acrylate (40 parts) diluted to 15% by weight of the polymer was added to a total of 8 nozzles each with an air spray pressure of 0.5 kg / cm ² . The feed was sprayed onto the drop fertilizer curtain at a flow rate of 400 ml / min, and hot air having a temperature of 55 ° C. and an air volume of 60 m ² / min was supplied to the lower end of the fertilizer curtain to simultaneously spray spray and dry the solution. The coating yield of latex was 82-87%, and even when the latex coating amount was 15% by weight of the fertilizer, the fertilizer particles were uniformly coated without agglomeration.

C) the effect of silicate-latex double coating

According to the method of Example 2-A), only the latex solution having a concentration of 10% was directly sprayed and coated on the spherical fertilizer without applying the silicate-based coating of Example 1-A), and its dissolution rate in water was changed to silicate-latex. It was fertilized with that of the double coated fertilizer (Table 2). The latex solution was directly coated on the fertilizer without silicate base coating, so that the surface of the fertilizer absorbed moisture during the coating, so that the surface of the fertilizer was dissolved in the case of urea. The fertilizer powder was contained in the latex film. On the contrary, the fertilizer with silicate-based coating did not cause any dissolution or disintegration of the fertilizer in the coating, so that it was possible to make a uniform Latax coating, and the fertilizer dissolution rate control ability was significantly improved. On the other hand, it has also been found that the initial dissolution rate of the fertilizer can be arbitrarily delayed by increasing the base coating amount of the silicate.

[Table 2]

Dissolution Rate of Silicate-latex Double-Coated Fertilizers in Water

Tested fertilizer: spherical element, particle size 3-5 mm.

Sodium silicate solution: silicon oxide / sodium oxide = 3.4, solution concentration 25%.

Latex solution: styrene (60 parts) -2-ethylhexyl acrylate (40 parts) copolymer latex, solution concentration 10%.

Coater: Fluidized bed coater.

Note: Since the dissolution rate of fertilizer is about 2-3 times faster than that at room temperature (25 ℃) in water at 40 ° C, the fertilizer is actually used at room temperature than the dissolution duration suggested here. The ship stays longer.

Example 3

Coating of Latex Solution with Additives

A) Coating of latex solution with powder of insoluble inorganic substance

40 parts of styrene 60 parts-2-ethylhexyl acrylate of 45% of concentration (1) 55.0 g, (2) 54.4 g, and (3) 53.3 g of the weight ratio of total solids were 1/99 and 2/98, respectively. And adding 0.25 g, 0.50 g, and 1.0 g of talc powder up to 400 mesh to 4/96 and diluting with water so that the concentration of the solution is 10% by weight, followed by stirring each solution. The silicate-coated particles were sprayed and coated by 500 g of spherical elements having a diameter of 3-5 mm by the method of Example 2-A) and heat-treated. The dissolution rate of the coated fertilizer in water was the same as in Table 3. The addition of fine powders of insoluble inorganic materials could change the elution form of fertilizer from initial delay type to linear type by arbitrarily changing the added amount, while reducing the stickiness of the solution during spraying and coating of the latex solution, thereby reducing the particles during coating. The mass of liver could be prevented.

B) coating of latex solution to which an aqueous solution of thermosetting resin is added;

30 g of urea, 130 g of formaldehyde aqueous solution having a concentration of 37%, and 63 g of water were mixed and stirred at 30 ° C. for 12 hours to prepare an aqueous solution of incomplete polymerized urea resin having a concentration of 40%. 0.625 g, 1.25 g and 2.5 of the aqueous urea resin solution so that the weight ratio of the total solids to the latex stock solutions (1), (2) and (3) above are 1/99, 2/98 and 4/96, respectively. g each was added, and the latex solution was coated in the same manner as described in item a). The dissolution rate of the coated fertilizer in water was the same as in Table 3. By heat-treating the coated fertilizer at 75 ° C. for 30 minutes, the initial fertilizer dissolution rate of the coated fertilizer was decreased, and as the amount of the thermosetting resin was increased, the coating swelling of the coated particles in water was suppressed.

[Table 3]

Dissolution Rate of Latex-Coated Fertilizer with Additives in Water

Tested fertilizer: spherical element, particle size 3-5 mm.

Coating of Sodium Silicate: Sodium Silicate / Urea = 5/100 (parts by weight)

Latex coating with additives: polymer layer / element = 5/100 (parts by weight)

Latex solution: styrene (60 parts) -2-ethylhexyl acrylate (40 parts) Copolymer latex, solution concentration 10%.

Urea-formaldehyde resin aqueous solution: Urea / 37%

Formaldehyde = 30/130 (parts by weight), solution concentration 40%.

Note: Refer to Note in Table 2.

Example 4

Change in latex type

A) Coating of vinyl chloride and vinylidene chloride emulsion copolymer latex solution

133.3 g of vinyl chloride and vinylidene chloride copolymer latex solutions diluted to 15% solids were sprayed and coated onto 500 g of 3-5 mm spherical urea coated with silicates. Coating was performed according to the method of Example 2-A), but only the coating temperature was set to 55 ° C. There was no phenomenon of agglomeration between the fertilizer particles either in the middle of coating or in the static state after completion of coating. The coating of vinyl chloride- and vinylidene chloride-based latex-coated fertilizers showed a large tensile force that hardly swells in water. Especially, the coating of vinylidene chloride-vinyl chloride-acrylate copolymer latex has extremely low moisture permeability. As shown in Table 4, the fertilizer dissolution rate control ability is shown.

[Table 4]

Dissolution Rate of Vinyl Chloride and Vinylidene Chloride Copolymer Latex-Coated Fertilizer in Water

Tested fertilizer: spherical element, particle size 3-5 mm.

Coating of Sodium Silicate: Sodium Silicate / Urea = 5/100 (parts by weight)

Latex coating: latex / element = 4/100 (parts by weight)

Properties of the latex: glass transition temperatures (A) 7 ° C, (B) 4 ° C, (C) 7 ° C, (D) 12 ° C and (E) 15 ° C.

Note: Refer to Note in Table 2.

B) coating of butadiene-based copolymer latex solution

250 g each of styrene-butadiene copolymer latex, acrylonitrile-butadiene copolymer latex acrylonitrile-butadiene copolymer latex and acrylonitrile-butadiene styrene copolymer latex solution diluted to a concentration of 10% solids The coating method described in a) was sprayed and coated on 500 g of spherical elements each having a particle diameter of 3-5 mm. Styrene-butadiene copolymer latex was added to 400 g of a latex solid concentration of 25%, 10 g of sulfur powder of 400 mesh or less and 2 g of 2-mercapto benzothiazole powder as a crosslinking accelerator, and for 6 hours in a ball mill at room temperature. After mixing vigorously, this was applied to the coating at a concentration of 10% solids. The coating temperature and the dissolution rate of the coating fertilizer were as in Table 5.

[Table 5]

Dissolution Rate of Butadiene-based Copolymer Latex Coated Fertilizer in Water

Type of latex: (A): Korea synthetic rubber, KSL 203.

(B): Korean synthetic rubber, KSL 202.

Note: Refer to Note in Table 2.

C) coating of ethylene-based copolymer latex solution

The coating method of Example 2-A) was applied to 500 g of 3-5 mm spherical urea coated with silicate of 250 g of ethylene-vinyl acetate copolymer latex solution diluted to a concentration of 10% solids and a low molecular weight polyethylene emulsion solution. Each was sprayed and coated. The dissolution rate of the coated fertilizer in water was the same as in Table 6.

[Table 6]

Elution Rate of Ethylene Copolymer Latex-Coated Fertilizer in Water

Properties of latex: (A) Tensile force: 60-70kg / cm ²

(B) Tensile force: 50-60kg / cm ²

(C) molecular weight: 18,000

(D) Molecular weight: 15,000

Note: Refer to Note in Table 2.

D) coating of chloroprene latex solution

To 500 g of chloroprene latex solution diluted to 10% solids content, 2.5 g of wet-pulverized zinc oxide powder under 400 mesh was added, and 0.5 g of butylaldehyde aniline was added as a crosslinking accelerator, and the mixture was boiled at room temperature for 6 hours. Vigorously mixed for a while. 250 g of a homogeneously mixed solution was taken and coated with 500 g of spherical oil having a silicate-coated particle diameter of 3-5 mm at a coating temperature of 35 ° C. according to the coating method of Example 2-A), followed by heat treatment at 70 ° C. for a time. . Due to the cross-linking reaction caused by zinc oxide, the coating was not sticky during or after the coating, and the swelling phenomenon of the polymer coating of the coating fertilizer in water was significantly reduced. The dissolution rate of the coated fertilizer in water was the same as in Table 7.

[Table 7]

Elution Rate of Chloroprene Latex Solution-Coated Fertilizer in Water

Note: Refer to Note in Table 2.

Example 5

Coating of mixed solution of latex

Two or more kinds of latex stock solutions were mixed and sprayed and coated onto 500 g of 3-5 mm spherical urea coated with silicate while stirring 250 g of the diluted solution so that the total solid concentration was 10%. Coating was performed according to the method described in Example 2-A). Since the dispersibility between these materials was good, it was possible to form a uniform film during spraying and coating, and it was possible to arbitrarily change the dissolution shape curve of the coated fertilizer according to the type and mixing ratio of the mixed latex.

A) coating of a mixed solution of acrylate-based latexes

The styrene-thiethylnuclear acrylate latex is composed of 60 parts-40 parts (SE1), 65 parts-35 parts (SE2), 70 parts-30 parts (SE3) and 75 parts by weight of styrene and 2-ethylhexyl acrylate. -25 parts (SE4) latexes were used in a fertilizer coated with a solution in which the weight ratio of polymer solids was SE1 / SE2 = 5/5, SE1 / SE3 = 5/5 and SE1 / SE4 = 5/5. The dissolution rate was the same as in Table 8.

B) coating of a mixed solution of styrene-butadiene copolymer ratchets

The dissolution rate of fertilizers coated with acrylate-based latex stock solution (SE1) and styrene-butadiene copolymer latex stock solution in a solution in which the weight ratio of polymer solids was 9/1, 8/2 and 6/4 was shown in Table 8. It was like

C) Coating of mixed solution of vinylidene chloride copolymer latex

In water of fertilizer coated acrylate latex stock solution (SE1) and vinylidene chloride-vinyl chloride-acrylate copolymer latex stock solution with a solution in which the weight ratio of polymer solids is 4/6, 2/8 and 1/9. The dissolution rate was the same as in Table 8.

D) sheathing of a mixed solution of natural latex

The dissolution rate of the fertilizer coated with the acrylate latex stock solution (SE1) and the natural latex stock solution so that the weight ratio of the polymer solid content was 8/2 was as shown in Table 8.

[Table 8]

Dissolution Rate of Coated Fertilizer in Solution Mixed with Multiple Latexes

SE1: Styrene-2-ethylhexyl acrylate copolymer latex (60 parts-40 parts).

SE1: styrene-2-ethylhexylacrylate copolymer latex (65 parts-35 parts).

SE1: Styrene-2-ethylhexyl acrylate copolymer latex (70 parts-30 parts).

SE1: styrene-2-ethylhexyl acrylate copolymer latex (75 parts-25 parts).

SE1: styrene-butadiene copolymer latex.

VDC: vinylidene chloride-vinyl chloride-acrylate copolymer latex, glass transition temperature 12 ° C

NR: natural latex.

Note: Refer to Note in Table 2.

Example 6

Compositional Changes of Copolymer Latex

Acrylate-based latex solutions having a glass transition temperature in the range of −10 ° C. to + 30 ° C. were sprayed and coated onto a spherical element having a silicate-doped particle diameter of 3-5 mm according to the method of Example 2-A).

A) Styrene-acrylate latex solution

The weight composition ratios of the two monomers of styrene and 2-ethylhexyl acrylate were 60 parts-40 parts (SE1), 65 parts-35 parts (SE2), 70 parts-30 parts (SE3) and 75 parts-35, respectively. 50 parts by weight of the latex (SE4) and styrene n-butyl acrylate monomer composition is 50 parts-50 parts (SE5) of 40 parts-60 parts (SE6) The latex solutions were diluted to 10% concentration and each coated 500 g of silicate coated spherical element with 250 g of the diluted solution. The coating temperature of each latex solution and the fertilizer dissolution rate of the coated fertilizer in water at 40 ° C. were as shown in Table 9.

[Table 9]

B) Methyl methacrylate-acrylate latex solution

Latex (MF1) having a weight composition ratio of methyl methacrylate and 2-ethylhexyl acrylate monomer is 6-0 parts-40 parts, and the weight composition ratio of monomers of methyl methacrylate and n-butyl acrylate is 50 parts-50 parts The latex (ME2) solutions were diluted to a concentration of 10% and 500 g of silicate coated globular elements were coated with 250 g of this diluted solution, respectively. The coating temperature of each latex solution and the fertilizer dissolution rate of the coated fertilizer in water at 40 ° C. were as shown in Table 10.

[Table 10]

Styrene-acrylate-acrylonitrile latex solution

The weight composition ratios of the monomers of styrene, 2-ethylhexyl acrylate and acrylonitrile were 45-45 parts-10 parts (SE7), 40 parts-40 parts-20 parts (SE8), and 37.5 parts-37.5 parts-25, respectively. The negative (SE9) latex solutions were diluted to a concentration of 10% and 500 g of silicate coated spherical elements were coated with 250 g of this diluted solution, respectively. The coating temperature of each latex solution and the fertilizer dissolution rate of the coated fertilizer in water at 40 ° C. were as shown in Table 11.

[Table 11]

D) Latex solution with crosslinking reactive monomer

The latex (SE10) which added 2 parts of divinylbenzene which are crosslinking-reactive monomers, and the latex which added 2 parts of diethylene glycol dimethacrylate to the reaction solution of 60 parts -40 parts of the weight composition bar of the monomer of styrene and 2-ethylhexyl acrylate (S311) 500 g of silicate-coated spherical urea was coated with 250 g of a solution diluted with 10% concentration of latex (SE12) to which 2 parts of etirol acrylamide was added. The coating temperature of each latex solution and the fertilizer melt rate in 40 degreeC water of the coating fertilizer were as Table 12.

[Table 12]

As a result of the addition of the crosslinking reactive monomer, the swelling of the coating of the coating fertilizer in water was significantly reduced.

The method of the present invention can be summarized as follows. That is, according to the method of the present invention, the silicate aqueous solution is first sprayed and coated on the surface of the granular fertilizer in the coater to form a uniform and smooth base film, and then the water-dispersible emulsion type latex is further coated to further pass water. By making a non-irritant coating, the dissolution rate of fertilizers in water can be remarkably alleviated to produce industrially useful sustainable fertilizers that have long term ineffectiveness with only one fertilization. Therefore, the coated fertilizer produced by the method of the present invention has the following industrial applicability as compared with the existing manufacturing techniques of the coated sustainable fertilizer. That is, -1) since the solvent used is water, there is no need for the equipment cost and operating cost required to recover expensive organic solvents, -2) there is no problem of environmental pollution due to unrecovered organic solvents, and -3) flammability during the coating process. There is no risk of fire or explosion due to the use of solvents. -4) It can reduce the latex coating amount by filling the surface of the bumpy fertilizer with cheap silicate. -5) Laminating the latex on the smooth silicate film like glass. Therefore, it is possible to make a latex film having a uniform thickness, so that the dissolution rate can be easily controlled, and 6) various fertilizers of various properties can be prepared since they can be used alone or in combination.

Claims (15)

A primary coating layer coated with 1-10 parts by weight of silicate based on 100 parts by weight of fertilizer particles to be coated, and a secondary coating layer coated with 1-10 parts by weight of polymer latex with respect to 100 parts by weight of fertilizer particles to be coated are integrally formed on the primary coating layer. Characterized persistent granular fertilizer. The sustained particulate fertilizer according to claim 1, wherein the coating material used for forming the primary coating layer is selected from the group consisting of sodium silicate, lithium silicate, potassium silicate, and ethyl silicate aqueous solution. The sustained granular fertilizer according to claim 2, wherein the aqueous sodium silicate solution is a mixed solution of silicon oxide and sodium oxide. The sustained granular fertilizer according to claim 1 or 3, wherein the weight ratio of silicon oxide and sodium oxide is 3.3, 3.75, or 4.2. (Correction) The method according to claim 1, wherein the coating material used for forming the secondary coating layer is made of natural latex, styrene-butadiene copolymer latex, acrylonitrile-butadiene copolymer latex, acrylonitrile-butadiene-styrene copolymer latex, styrene 2-ethylhexyl acrylate-acrylonitrile copolymer latex, acrylic polymer latex, chloroprene polymer latex, vinyl acetate polymer latex, isoprene polymer latex, vinyl chloride polymer latex, vinylidene chloride polymer latex alone and these Persistence granular fertilizer, characterized in that it is selected from the group consisting of an aqueous solution of a mixture of. Spraying and drying a 10-38% by weight aqueous silicate solution based on the weight of the fertilizer particles on the surface of the fertilizer particles to be coated in a fluidized bed coating device or a rotating cylindrical drum coating device to form a silicate coating layer; Spraying 5-20% by weight aqueous solution of polymer latex with respect to the weight of the fertilizer particles on the surface and dried to fix the latex coating layer integrally formed on the silicate. The method according to claim 6, wherein the concentration of the aqueous silicate solution is 25-30% by weight. The method of claim 6, wherein the concentration of the aqueous polymer latex solution is 10-15% by weight. The fluidized bed under a coating condition according to claim 6, wherein the feed rate is 2-20 ml per minute, the feed nozzle pressure is 0.2-5 kg / cm ^2, and the hot air temperature is 20-100 ° C. with respect to 500 g of the fertilizer to coat the aqueous silicate solution. Characterized by coating on the fertilizer particles. 10. The method of claim 9 wherein the coating conditions are a feed rate of 5-10 ml per minute, a feed nozzle pressure of 0.5-1 kg / cm ² and a hot air temperature of 60-80 ° C. The fertilizer to coat the aqueous solution of the polymer latex, the feed rate is half of the feed rate of the silicate solution, the feed nozzle pressure is 0.1kg / cm ² and the temperature of the hot air is 20-60 ℃ Coating the fertilizer surface in a fluidized bed nasal apparatus or a rotating cylindrical drum coating apparatus under phosphorus coating conditions. The method according to claim 6, wherein the polymer latex coating layer is sprayed with an aqueous solution of 0.1-2% by weight of inorganic mineral or polyvalent metal salt with respect to the total weight of the fertilizer and dried at 50-100 ° C. for 10 minutes-2 hours. 13. The method of claim 12, wherein the inorganic mineral is selected from the group consisting of talc and kaolin. The method according to claim 12, wherein the polyvalent metal salt is zinc nitrate. The method of claim 12 wherein said drying is carried out at 70-100 ° C. for 30 minutes to 1 hour.

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