JP2849466B2 - Granular coated agricultural material - Google Patents

Description

The present invention relates to a water-soluble agricultural material having a long-lasting effect, which is useful in the field of agricultural materials. More specifically, a granular agricultural material is coated with a film containing a polymer emulsion as a main component, and preserved by attaching a specific substance to the surface of the granular coated agricultural material having a lasting effect. It is intended to provide a granular coated agricultural material having improved properties.

[Conventional technology]

By coating quick-acting water-soluble agricultural material with a water-resistant film, the granular coated agricultural material that has been controlled to dissolve into the soil and has a long-lasting effect can be obtained by a single application of agricultural material. Its use is expanding rapidly because the stable agricultural effect can be maintained over the period. Currently, sulfur and organic solvent solutions of resins are mainly used as coating materials.However, it has been pointed out that sulfur gradually accumulates and acidifies soil. In addition, there are problems such as the danger of fire due to the use of organic solvents in the manufacturing process, safety problems for humans, and the problem of residual organic solvents in the coating of coated agricultural materials as products. Under such circumstances, it has been proposed to coat agricultural materials with an aqueous polymer emulsion. In the polymer emulsion-based coating material, in order to control the dissolution of agricultural materials to a high degree, it is necessary that the individual emulsion particles constituting the emulsion are sufficiently fused to form a highly uniform continuous film. On the other hand, coated agricultural materials may be subjected to temperature and load during storage, for example, when they are placed in a bag in summer, and in such a case, there is a problem that the particles adhere and solidify. is there. The former is improved by, for example, selecting a relatively soft polymer as a polymer constituting the polymer emulsion.However, if such a measure is adopted, the latter tends to deteriorate the caking resistance. It is not easy to satisfy the two requirements.

In consideration of such problems, various studies have been made on polymer emulsion-based coating materials, and improvements have been proposed.

For example, in the first step, a water-resistant coating is formed on the granular fertilizer at a coverage of 0.1 to 2% using an aqueous emulsion or an organic solution of a thermoplastic resin, and in the second step, the required coverage is obtained using an aqueous emulsion of the thermoplastic resin. A method for producing a granular coated fertilizer to be coated with a resin has been proposed (Japanese Patent Publication No. 60-18640).
No.). Although the production method prevents the dissolution of fertilizer during the second stage coating by the first stage coating, it uses a resin emulsion having a relatively high glass transition temperature (or minimum film formation temperature). Is difficult to form a sufficient continuous film, and it is difficult to control elution to a high degree. When an emulsion of a resin containing an organic solvent is used, the formability of a continuous film is improved to some extent, but there are problems such as the aforementioned danger in handling the organic solvent and the residual organic solvent in the coated agricultural material that is the product. Occurs. On the other hand, when a resin emulsion having a relatively low glass transition temperature is used, the formation of a continuous film is good, but the problem of consolidation of fertilizer during storage is likely to occur. Next, a double-coated continuous fertilizer characterized by having a primary coating composed of a silicate or a silicate ester and a secondary coating composed of a polymer latex on the surface of the granular fertilizer has also been proposed (Japanese Patent Application Laid-Open (JP-A) No. 2002-122,837). In the invention, when a resin emulsion having a relatively high glass transition temperature is used, it is difficult to form a sufficient continuous film, and when a resin emulsion having a relatively low glass transition temperature is used. Does not solve the problem that the fertilizer during storage is liable to condense. In addition, a slow-release coated fertilizer which uses a coating material mainly composed of an aqueous emulsion of a resin and is not coated with a resin film having a glass transition temperature of 60 ° C. or higher has been proposed (Japanese Patent Application Laid-Open No. Sho 64). In the case of using such a resin having a high glass transition temperature, it is difficult to form a sufficient continuous film, it is difficult to control a high degree of elution, and to improve the formability of the continuous film. When a film-forming aid or a plasticizer is used, the resulting film has a disadvantage that the film is softened and consolidation is likely to occur. After coating the solid fertilizer with a coating material mainly composed of an aqueous emulsion of a thermoplastic resin and a melamine resin, a temperature of 70 ° C.
A slow release coated fertilizer obtained by heat treatment has also been proposed (JP-A-64-3094).
Although some improvement was observed in the compatibility of continuous film formation and consolidation resistance, the degree of improvement was insufficient, and the coating material was given sufficient continuous film formability to control elution to a high degree. In this case, the coated agricultural material is likely to be consolidated. There is also a problem that formaldehyde, which is a harmful substance, is generated during coating and remains in products.

[Problems to be solved by the invention]

As described above, in the coating of granular agricultural materials using an aqueous polymer emulsion, the polymer emulsion forms a highly uniform continuous film, and the elution of the water-soluble agricultural materials is highly controlled and preserved. Conventionally, it has been extremely difficult to obtain a granular coated agricultural material in which the coated agricultural material particles do not adhere to each other and solidify.

In view of such circumstances, the present invention is a granular coated agricultural material that is coated with a polymer emulsion having good formability of a continuous film, has excellent agricultural material dissolution controllability, and is coated with the coated agricultural material particles during storage. The purpose of the present invention is to provide a granular coated agricultural material that does not adhere and has excellent caking resistance.

[Means for solving the problem]

The present inventors have conducted intensive studies to achieve the above object, and as a result, by further attaching a specific material to the surface of a coated agricultural material coated with a coating mainly composed of a polymer emulsion, We found that we could give the target solidification resistance, and examined it in more detail based on such knowledge,
The present invention has been completed.

That is, the present invention relates to a surface of a granular agricultural material coated with a coating mainly composed of a polymer having a glass transition temperature of 50 ° C. or less and a gel content of 75% by weight or more. A granular coated agricultural material characterized by adhering one or more selected from silica gel, alkali silicate and alumina sol at a rate of 0.01 to 5% by weight based on the total weight of the coated agricultural material. To provide.

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

The polymer emulsion in the present invention is obtained by emulsion polymerization of one or more types of radically polymerizable monomers by a known emulsion polymerization method.

The type of monomer used is not particularly limited, but examples of preferred monomers include methyl acrylate, ethyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, Acrylic esters such as glycidyl acrylate, diethylene glycol diacrylate, and trimethylolpropane triacrylate; methacrylic esters such as methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, 2-hydroxyethyl methacrylate, and glycidyl methacrylate , 1,3-butadiene, pentadiene, 2-
Methyl-1,3-butadiene, 2-chloro-1,3-butadiene, aliphatic conjugated dienes such as chloroprene, styrene, α-methylstyrene, 4-methylstyrene, 2-hydroxymethylstyrene, 4-ethylstyrene, 4-ethoxystyrene, 3,4-dimethylstyrene, 2-chlorostyrene, 4-chlorostyrene, 4-chloro-3-methylstyrene, 2,4-dichlorostyrene, aromatic styrene derivatives such as divinylbenzene, acrylic acid, Methacrylic acid, monocarboxylic acids such as crotonic acid, fumaric acid, itaconic acid, dicarboxylic acids such as maleic acid and anhydrides or monoalkyl esters thereof, acrylonitrile,
Amide compounds such as vinyl cyanide compounds such as methacrylonitrile, acrylamide, methacrylamide, N-methylolacrylamide, N-methoxymethylacrylamide, N-ethoxymethylacrylamide, N-propoxymethylacrylamide, and Nn-butoxymethylacrylamide; Amine compounds such as methylaminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminopropyl (meth) acrylate, diethylaminoethyl (meth) acrylate, 2-vinylpyridine and 4-vinylpyridine, and halogen substitution such as vinyl chloride Examples include vinyl compounds and carboxylic acid vinyl esters such as vinyl acetate.

The method of emulsion polymerization is not particularly limited, and it is usually advantageous to carry out the polymerization in an aqueous dispersion in the presence of an emulsifier. The emulsifier to be used is not particularly limited, but is usually an alkyl diphenyl ether disulfonate, a higher alcohol sulfate, an anionic surfactant such as alkyl allyl sulfonic acid, a polyoxyethylene alkyl ether, a polyoxyethylene alkyl ester, or the like. A nonionic surfactant, a cationic surfactant, or a single or mixed system of amphoteric surfactants is used. There is no particular limitation on the polymerization initiator, and any initiator can be selected from peroxodisulfate, hydrogen peroxide, benzoyl peroxide, and a redox initiator. The method of adding the polymerization initiator is not particularly limited, and any method can be selected from conventionally known methods such as initial batch addition, divisional addition, and continuous addition. Various additives conventionally used in emulsion polymerization, for example, mercaptans, alkylthiols, chain transfer agents such as carbon tetrachloride, chelating agents, sodium hydroxide, potassium hydroxide,
A neutralizing agent such as aqueous ammonia or a salt such as a phosphate or a carboxylate can be arbitrarily selected and used as needed. The temperature of the polymerization reaction is not particularly limited, and is usually about 30 to 100 ° C, preferably about 50 to 90 ° C.
There is no particular limitation on the method of adding the monomer,
It can be arbitrarily selected from conventionally known methods such as continuous addition, divided addition in other stages, or initial or late batch addition of only a specific monomer. The particle size of the polymer emulsion is not particularly limited, but the particle size of the particles formed by emulsion polymerization is usually 0.05 to 1 μm, and is preferably adjusted to about 0.1 to 0.7 μm. In order to adjust the particle size of the latex arbitrarily and with good reproducibility, a seed polymerization method can be used.

Various other additives may be added to the polymer emulsion as desired. Examples of these additives include a dispersant, a bactericide, a viscosity modifier, an antioxidant, a water-proofing agent and other salts, and these may be added before, during or after polymerization as necessary. May be added. When the polymer emulsion used in the present invention is used as a coating material, it may be used alone or as a mixture of two or more polymer emulsions. Inorganic pigments such as talc, clay and calcium carbonate, organic pigments such as polystyrene latex having a glass transition temperature of about 60 ° C or higher, starch, sodium alginate , Natural water-soluble polymers such as cellulose, polyvinyl alcohol,
A synthetic or semi-synthetic water-soluble polymer such as modified starch and carboxymethyl cellulose, salts such as calcium chloride and sodium chloride, silica sol, and a crosslinking agent may be blended. It is also possible to add a film-forming aid, a plasticizer or a small amount of an organic solvent for the purpose of improving the film-forming property or drying property of the polymer emulsion. Examples of these are ethylene glycol n-butyl ether. ,
Dipropylene glycol methyl ether acetate, diethylene glycol n-butyl ether, propylene glycol n-butyl ether, ethylene glycol phenyl ether, propylene glycol phenyl ether, ethylene glycol mono-2-ethylhexyl ether, propylene glycol diacetate, dibutyl phthalate, dioctyl phthalate, Dioctyl sebacate,
Examples include benzyl alcohol, toluene, acetone, methanol, ethanol, n-propanol, isopropanol, butanol, n-hexane, cyclohexane and the like. The solid content concentration of the coating composition is not particularly limited, but is usually in the range of 1 to 50% by weight, and is arbitrarily adjusted according to the coating method and the like.

The glass transition temperature of the polymer emulsion of the coating material of the present invention can be arbitrarily set depending on the type of the monomer used and the like. The glass transition temperature measured in the state of the coating material formulation with the addition of additives, and if there is more than one glass transition temperature, the lowest glass transition temperature,
It is preferably 50 ° C. or lower. The glass transition temperature can be easily measured, for example, by subjecting the dried solid to a differential scanning calorimetry or the like. In addition, in order to prevent the difficulty of uniform coating due to the adhesion of the agricultural material particles in the step of coating the granular agricultural material, the gel content of the polymer constituting the polymer emulsion is 75% by weight or more. Preferably, there is. The gel content in the present invention refers to the content of a polymer insoluble in toluene, which is obtained by adding 30 ml of toluene to 0.5 g of a dry solid substance of a polymer emulsion, shaking for 4 hours, and then filtering through a wire mesh of $ 300. It is the weight percentage of the dry weight relative to the weight of the original solid.

The method for coating the granular agricultural material of the present invention is not particularly limited.
(About 130 ° C.) or a method of spray-drying the coating material composition of the present invention continuously or intermittently on granular agricultural materials rolling on a rotating pan. The coating operation may be performed in one stage with one type of coating material, or may be performed in multiple stages using one or two or more types of coating materials to form a multilayer coating. When performing multilayer coating, it is also possible to use a small amount of a coating material that does not use a polymer emulsion, for example, a resin or an organic solution such as polyethylene wax. Although there is no particular limitation on the coating ratio, the ratio of the coating material weight to the total weight of the granular coated agricultural chemical is usually 2 to 2 due to the controllability of dissolution and practical problems.
It is preferably in the range of about 30%.

The granular agricultural material in the present invention is a particulate fertilizer or a water-soluble pesticide, and the shape and size of the particles are not limited, but the particle shape is preferably spherical or cylindrical, and the particle size is about 0.5 to 10 mm. Are preferred. There are no particular restrictions on the type of fertilizer, and examples thereof include advanced chemical fertilizers, chemical fertilizers, urea, ammonium sulfate, potassium chloride, potassium sulfate, potassium nitrate, sodium nitrate, ammonium phosphate, and potassium phosphate. There is no particular limitation on the type of water-soluble pesticide, and there are herbicides, insecticides, fungicides, plant regulators, acaricides, nematocides, pesticides, repellents, attractants, and the like. To give an example,
2,4-D, sodium dichloropropionate, hydroxyisoxazole, dimethylimol paraquat, glyphosate, picloram, molinate, butoxycarboxime, sodium azide, alkylbenzylethylethanol, ammonium chloride, sulfuric acid, trichloroacetic acid, etc. is there. The granular agricultural material in the present invention may be a single particle of these fertilizers and water-soluble pesticides, or may be particles of a mixture of two or more. If necessary, talc, white carbon, clay,
It may be added with lignin sulfonic acid or the like.

In the present invention, in addition to these, one or more kinds selected from silica sol, alkali silicate and alumina sol are essential. Silica sol is a generally spherical aqueous dispersion of silicic anhydride having a particle size of about 1 to 100 nm, and is not particularly limited in the present invention, and may have any pH, particle size, silicic anhydride content, and sodium oxide content. Can be selected and used. Further, the surface of the particles may be subjected to an aluminum treatment, the particles may have a special particle shape, or the like, and an organosilica sol in which the dispersion medium is other than water may be used. The alkali silicate is not particularly limited, and may be arbitrarily selected from sodium silicate, potassium silicate, lithium silicate, ammonium silicate and the like. These are usually used in the form of an aqueous solution, but may be partially colloidal. The alumina sol is not particularly limited, and is an aqueous dispersion of alumina hydrate (boehmite) having a colloidal size of about 2 to 200 nm. The particle shape may be any of feather-like, rod-like, or granular. Any type of anion used as a stabilizer can be used, such as Cl ⁻ , CH ₃ COO ⁻ and NO ₃ ⁻ . The granular coated granular agricultural material of the present invention is obtained by coating one or more of these silica sol, alkali silicate and alumina sol on the surface of the granular agricultural material coated with a coating mainly composed of a polymer emulsion. In addition, the dry weight of the total weight of
It is obtained by adhering at a rate of 0.01 to 5%. If the amount of adhesion is less than 0.01%, it is difficult to impart the required caking resistance, and if it exceeds 5%, the caking resistance is not further improved and is not practical. There is no particular limitation on the method of adhering one or more selected from silica sol, alkali silicate and alumina sol, as in the case of coating with a coating material containing a polymer emulsion as a main component. A preferable example is a method of spray-drying continuously or intermittently a granular agricultural material rolling on a pan.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but it goes without saying that the present invention is not limited to these examples.

In addition, the measurement of the physical property of the granular coated agricultural material shown in the Example was performed by the method shown below.

(Dissolution rate) 10 g of the granular coated agricultural material was immersed in 200 ml of water, allowed to stand for a certain period of time in an environment of 25 ° C., and then the ionic concentration in the water was measured and calculated.

Taken up in polyethylene of cup (anti-caking property) 100 g granular covering agricultural material, 40 ° C., under a load of 450 g / cm ² at 60% RH environment and left for 7 days, and adhesion between the particles caking The weight of the granular agricultural material thus obtained was measured and expressed as a percentage by weight as a consolidation rate.

<Preparation of Polymer Emulsion> A monomer mixture obtained by adding 65 parts by weight of styrene, 28 parts by weight of butadiene, 5 parts by weight of methyl methacrylate, 2 parts by weight of acrylic acid, and 0.2 part by weight of t-dodecylmercaptan as a chain transfer agent. Prepared.

Next, 50 parts by weight of deionized water, 0.2 parts by weight of potassium hydroxide, 0.15 parts by weight of sodium dodecylbenzenesulfonate and 0.8 parts by weight of potassium peroxodisulfate were mixed and dissolved to prepare an aqueous initiator solution. The high-pressure reaction vessel equipped with a stirrer was replaced with nitrogen, and 100 parts by weight of deionized water, 0.1 part by weight of sodium dodecylbenzenesulfonate and 2.5 parts by weight of seed latex were charged, and the internal temperature was raised to 80 ° C. while stirring at 300 rpm. . While keeping the temperature of the contents at 80 ° C,
The polymerization was completed by adding the monomer mixture prepared in advance and the aqueous initiator solution uniformly and continuously over 5 hours and 6 hours, respectively.

The polymerization addition rate of the monomer in the obtained polymer emulsion calculated by the weight method was about 97%.

Furthermore, residual monomers were removed from the obtained polymer emulsion by steam distillation, and an appropriate amount of aqueous ammonia was added to adjust the pH of the polymer emulsion to 8. The gel content of the latex at room temperature was measured.
The glass transition temperature was 34 ° C. measured by a differential scanning calorimeter (DSC220C, manufactured by Seiko Instruments Inc.) at 84% by weight. This polymer emulsion is referred to as polymer emulsion A.

Polymer emulsions B to E were prepared in the same manner. Table 1 shows these polymer emulsions.

Example 1 To 70 parts by weight of a polymer emulsion A, 10 parts by weight of calcium carbonate (manufactured by Nitto Powder Chemical Co., Ltd., NS-100) and 20 parts by weight of polystyrene emulsion (L-8801, manufactured by Asahi Kasei Kogyo) (solid content conversion) were added. Thus, a coating material composition was prepared. Next, using a coating apparatus of a heated jet type shown in FIG. 1, coating was applied to an advanced chemical fertilizer (average particle size: about 4 mm, manufactured by Asahi Kasei Corporation) under the following conditions. Further, silica sol (Snowtex 20 manufactured by Nissan Chemical Industries, Ltd.) was spray-dried to an adhesion rate of 0.1% by weight to obtain a granular coated agricultural material.

Coating conditions Advanced granulated granular fertilizer 4 kg Coating composition solids 10% Spraying time Approx. 250 minutes Hot air temperature 90-120 ° C Air volume 145-170 Nm ³ / hr Coverage 15% by weight
The dissolution rate was measured and the test for solidification resistance was performed. The results are shown in Table 3.

Examples 2 to 5 Using the polymer emulsions B to E, a granular coated fertilizer was prepared in the same manner as in Example 1. These are summarized in Table 2. Table 3 shows the results of the measurement of the dissolution rate and the test results of the solidification resistance.

Comparative Examples 1 to 5 In the same manner as in the examples, granular coating fertilizers were prepared according to the coating composition shown in Table 2 and the coating ratio. Similarly, the dissolution rate was measured and the caking resistance test was performed on these. The results are shown in Table 3.

[Effects of the Invention] The present invention is intended to prevent the adhesion between fertilizer particles by attaching a specific material to the surface of a granular agricultural material coated with a coating mainly composed of a polymer emulsion, and to prevent solidification. Thus, the present invention provides a granular coated agricultural material having significantly improved storage stability.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a jet coating apparatus used in Examples and Comparative Examples of the present invention. DESCRIPTION OF SYMBOLS 1 ... Coating composition introduction pipe 2 ... Nozzle, 4 ... Wire mesh 3 ... Granular agricultural material, 5 ... Hot air introduction pipe

Continuation of front page (56) References JP-A-2-167880 (JP, A) JP-A-51-30600 (JP, A) JP-A-56-5394 (JP, A) (58) Fields studied (Int .Cl. ⁶ , DB name) C05G 3/00 A01N 25/26

Claims (1)

(57) [Claims] 1. A surface of a granular agricultural material coated with a coating mainly composed of a polymer emulsion comprising a polymer having a glass transition temperature of 50 ° C. or lower and a gel content of 75% by weight or more. A granular coated agricultural material, wherein one or more selected from silica sol, alkali silicate and alumina sol are adhered at a ratio of 0.01 to 5% by weight based on the total weight of the coated agricultural material.