JPS6335503A - Production of granular agricultural chemical - Google Patents

Abstract

PURPOSE:To obtain a granular agricultural chemical having low bulk density, large diameter of the granule and exhibiting excellent hydration and disintegration properties when thrown into water, by using a concentrated dispersed slurry containing water-insoluble powder of agricultural chemical and subjecting the slurry to counter-current spray-drying under a specific condition. CONSTITUTION:A granular agricultural chemical containing >=50% granules having bulk density of 150-400g/l is produced by spray-drying a concentrated dispersed slurry containing water-insoluble powder of agricultural chemical and having a viscosity of 1-10,000cps, preferably 10-5,000cps (25 deg.C, B-type viscometer at 30rpm with rotor No.2) and a surface tension (25 deg.C) of 10-72dyn/ cm, preferably 20-70dyn/cm through a nozzle having a diameter of 0.5-40mm under a spray pressure of 5-250kg/cm<2> using a spray dryer having an inlet hot air temperature of 150-300 deg.C and exhaust hot air temperature of 60-120 deg.C under a condition satisfying the relationship of the formula. The dispersing agent used in the preparation of the above slurry is a water-soluble polymer, metal phosphate, etc., containing unsaturated carboxylic acid (derivative) or styrenesulfonic acid salt as essential component.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for granulating a poorly water-soluble agricultural chemical dispersion slurry by countercurrent spray drying, and more particularly, to a method for granulating a poorly water-soluble pesticide dispersion slurry,
The present invention relates to a method for producing granular agricultural chemicals that are advantageous in terms of transportation cost, easy to suspend, and have physical properties that do not cause environmental pollution such as dust.

[Conventional technology and its problems]

In addition to wettable powders, there are various formulations of active pesticide formulations, such as granules, emulsions, and flowable formulations.Wettable powders can contain a high concentration of active ingredients, and at the same time, It is excellent in that it can be formulated regardless of the type.

However, in hydrating powders, the agricultural chemical ingredients are ground into fine powder along with inorganic mineral powders, etc., so when preparing the spray liquid for use, the fine powder flies up as soon as the bag is opened, and the total amount of chemicals required is 90% of the time. was on.

Therefore, in recent years, attempts have been made to make hydrating powders into granules.

However, when conventional wettable powders are made into granules as they are, there are various problems such as not disintegrating in water or not providing a stable dispersion.

As a method to solve this problem, a granular wettable powder (Japanese Patent Publication No. 53-1
No. 2577) has also been disclosed, but it is not satisfactory in terms of initial dispersibility, self-dispersion, suspension stability, and environmental pollution caused by powder.

Furthermore, when a pesticide-dispersed slurry is granulated using a co-current spray dryer, it is difficult to produce granules with a low bulk density and a large particle size, which is not fully satisfactory in terms of dusting, transportation costs, etc. Furthermore, there is a problem that the cost of spray drying is high.

Measures for Solving Problem c] Therefore, the present inventors lowered the bulk density of the powder and granules, and the particle size of the granules was increased (and also improved in hydration and disintegration when put into water). As a result of extensive research in order to obtain a granular water-dispersible powder that provides an excellent and stable dispersion at a low cost, the above objective was achieved by granulating it by spray drying using a self-flow method under specific conditions. The present invention has been completed based on the discovery that this can be achieved.

That is, the present invention provides m'fe containing agrochemical powder that is insoluble in water.
The present invention relates to a method for producing granular agricultural chemicals, which comprises countercurrently spray-drying a t-dispersed slurry under the following conditions (i) and (ii).

(i) 6.8≦de0・70×P−0・4 Q x
p (1-22Xσ0・60(ii) Spray nozzle diameter 0.5-4.O1, spray pressure 5-250 kg/c 2
(Pressure nozzle) Hot air inlet temperature 150-300°C Exhaust air temperature 60-120°C According to the present invention, more than 50% of the particles have a bulk density of 150-40°C.
It is possible to obtain a powdery agricultural chemical having physical properties of 0 g/I and excellent physical properties such as hydration and disintegration when added to water.

The meaning of formula (i) is that the particle diameter and bulk density after spray drying are determined by the spray nozzle diameter de, spray pressure P, and slurry viscosity μ.
, is governed by the exponential function of the slurry surface tension σ.

That is, when the spray pressure is constant, increasing the nozzle diameter will increase the size of the sprayed droplets, but the size of the droplets at this time is closely related to the slurry viscosity and the slurry surface tension. Furthermore, when the nozzle diameter is constant, the smaller the spray pressure is, the larger the droplet diameter will be, but in this case as well, the slurry viscosity and surface tension are closely related.

According to the research conducted by the present inventors, the index multiplied by each variable is 0.7th power for the nozzle diameter de, -0 for the spray pressure,
4th power, 0.22nd power for slurry viscosity, 0.6th power for slurry surface tension, and if sprayed under conditions where these products are 6.8 or more, the bulk density will be low and the particle size will be large. It has been found that powder-free particles with excellent dispersibility in water can be obtained. At this time, the nozzle diameter is 0.5
~4.0mm, preferably 0.8-3.8mm, jet 2
8 Pressure is 5-250 kg/c+w”, preferably 1
0~80kg/cm2, slurry viscosity is 1~1O000
cps (25℃> (B type 3゜rpm magnetic 2), preferably 10 to 5000cps, slurry surface tension is 1
0 to 72 dyn/cm (25°C), preferably 20 to
70dyn/cm, hot air inlet temperature 150-300℃,
Preferably 150~250℃, exhaust air temperature 60~120℃
°C1 is preferably 80-110'C.

Also, the average particle size of the spray-dried particles is 10! Fine powder below BR,
That is, when zeolite, silica, other inorganic substances or metal soaps are added and mixed, a powder with excellent fluidity can be obtained.

In addition, the dispersants used in pesticide dispersion slurry include the following (
One or more types selected from the compound groups 1) to (4) are preferred. By using these, it is possible to obtain powder particles that have excellent hydration properties and disintegration properties when added to water.

fl) A water-soluble or water-dispersible polymer containing as an essential component one or more selected from the monomer group consisting of unsaturated carboxylic acids and derivatives thereof.

(2) A water-soluble or water-dispersible polymer containing styrene sulfonate as an essential constituent monomer.

(3) A formalin condensate of a sulfonated aromatic compound or a salt thereof, which may have a hydrocarbon group as a substituent.

(4) Phosphate metal salt.

The above dispersants (11 to (4)) according to the present invention will be specifically explained.

(1) A water-soluble or water-dispersible polymer containing as an essential component one or more monomers selected from the monomer group consisting of unsaturated carboxylic acids and derivatives thereof.

Monomers used in the production of this polymer include unsaturated monocarboxylic acids such as acrylic acid and methacrylic acid, unsaturated dicarboxylic acids such as maleic acid, and derivatives thereof such as alkyl esters (methyl esters) of the above acids. ), alkali metal salts (such as soda salts), ammonium salts and organic amine salts (such as triethanolamine salts), and mixtures thereof.

In addition to these monomers, copolymerizable monomers such as vinyl acetate, isobutylene, diisobutylene, and styrene can also be added as copolymerization components.

The method of polymerizing these monomers is conventionally known. Although there are no particular restrictions on the ratio of monomer components and the degree of polymerization of the polymer, it is necessary that the polymer is at least water-soluble or water-dispersible.

Specific examples include acrylic acid polymers, methacrylic acid polymers, copolymers of acrylic acid and methacrylic acid, copolymers of acrylic acid and methacrylic acid polyoxyethylene ester, and acrylic acid and acrylic acid methyl esters. Copolymers of acrylic acid and vinyl acetate, copolymers of acrylic acid and maleic acid, copolymers of maleic acid and isobutylene, copolymers of maleic acid and styrene, etc. Salts with alkali metals, ammonia and organic amines may be mentioned. Two or more kinds of these polymers can also be used.

(2) Water-soluble or water-dispersible polymers containing styrene sulfonate as an essential constituent monomer Styrene sulfonate homopolymers can be easily produced by polymerizing styrene sulfonate or by sulfonating polystyrene. can be manufactured. The styrene sulfonate polymer has a skeleton represented by the following formula.

Molecular weight is 1ooo or more, preferably 10,000 to 300
Ten thousand. H means alkali metal salts such as Li, Na, K, etc., or NH, alkylamine, alkanolamine, etc.

In addition, copolymers of styrene sulfonate and other monomers can be obtained by copolymerizing styrene sulfonate and other monomers, or by sulfonating a copolymer of styrene and other monomers. Therefore, it can be easily manufactured. Examples of copolymerization partners include hydrophobic monomers such as alkyl acrylate, alkyl methacrylate, vinyl alkyl ether, vinyl acetate, ethylene, propylene, butylene, butadiene, diisobutylene, vinyl chloride, vinylidene chloride, acrylonitrile, and styrene. body, and acrylic acid,
Methacrylic acid, maleic acid, fumaric acid, maleic anhydride, vinyl alcohol, acrylamide, methacrylamide, diacetone acrylamide, N-vinylpyrrolidone, 2-acrylamido-2-methylpropanesulfonic acid, methacrylsulfonic acid, xylene sulfonic acid, naphthalene Hydrophilic monomers such as sulfonic acid are used. Preferred copolymers include (meth)acrylic acid-styrene sulfonic acid copolymer salts. (in the copolymer)
The molar ratio of meth)acrylic acid and styrene sulfonic acid is 1/
It is 10 to 10/1, preferably 1/3 to 7/1. Moreover, the average molecular weight is 10,000 to 1,000,000, preferably 10,000 to 700,000. Salts of the copolymer include sodium salts, potassium salts, ammonium salts, jetanolamine u, I-liethanolamine salts, monoisopropanolamine salts, diisopropanolamine salts, triisopropanolamine salts. , 2-amino-2-methylpropane-1,3-diol salt, and the like. Further, an unneutralized portion may be left as long as it does not impede performance.

(3) Formalin condensates of sulfonated aromatic compounds that may have hydrocarbon groups as substituents or their salts Specifically, petroleum sulfonic acid derivatives, lignin sulfonic acid derivatives, naphthalene sulfonic acid derivatives, xylene sulfonic acid derivatives , formalin condensates such as alkylbenzenesulfonic acid derivatives.

These formalin condensates are obtained by sulfonating, for example, naphthalene, alkyl-substituted benzene, alkyl-substituted naphthalene, anthracene, alkyl-substituted anthracene, lignin, petroleum residue having an aromatic ring, etc. by the method -i, and then salt formation. It is obtained by reaction and further formalin condensation. In this case, the degree of condensation is preferably 2-30, more preferably 3-10. Here, when the degree of condensation is less than 2, the effect of condensation is small,
Moreover, if it exceeds 30, the molecular weight becomes high, which causes practical problems in terms of solubility and the like.

Various aromatic compounds can be used, but lignin, xylene, toluene, naphthalene, or alkylnaphthalene having 1 to 6 carbon atoms may be used, and of course, mixtures thereof may also be used. good.

As salts, alkali metals such as sodium and potassium, alkaline earths such as calcium, amines, ammonium salts, etc. are also used.

(4) Examples of metal phosphate salts include sodium, potassium, and other alkali metal salts such as tripolyphosphoric acid, pyrophosphoric acid, hexametaphosphoric acid, primary phosphoric acid, secondary phosphoric acid, and tertiary phosphoric acid; They may be used alone or in combination of two or more.

The blending ratio of the dispersant in the wettable powder is preferably 1 to 50 parts by weight, more preferably 2 to 40 parts by weight. In particular, in the case of high concentration drug substance, the amount is preferably 10 parts by weight or more.

Agrochemicals used in the present invention include insecticides, fungicides, acaricides, herbicides, and plant growth regulators. Examples of the insecticides include -naphthyl-N-methylcarbamate (NAC),
．． 0-diethyl-〇-(3-oxo-2-phenyl-2
11-pyridazin-6-yl) bosborothioate (Ofunack), acaricides such as tricyclohexyltine hydroxide (Plictran), hexakis (B, B-
dimethylphenethyl) distanoxane [Osadan], and as a fungicide, zinc ethylene bis(dithiocarbamate) [Daisen (
Dithane), bisdimethyldithiocarbamoyl-zinc ethylene bisdithiocarbamate [Bis-dith
ane) ), bis(dimethylthiocarbamoyl)disulfide [Thiaram], methyl-1-(butylcarbamoyl)-2-henzimidazole carbamate [Benomyl], tetrachloroisophthalonitrile [Dac
onil) ), 3-(3,5-dichlorophenyl)-5-methyl-5-
Vinyl-1,3-oxazolidine 2,4-dione [Ron i fan], N-(3,5-dichlorophenyl)-L2-dimethylcyclopropane-1
, 2-dicarboximide [Sumilex
ex) ), 3-(3,5-dichlorophenyl)-N-
Isopropyl-2,4-dioxoimidazolidine-1-
Carboxamide (Rovrol), 3
-aryloxy-1,2-benzisothiazole 1,1-
Dioxide (Oryzesate)
.

Diisopropyl 1,3-dithiolane-2-ylidenemalonate [Fuji-One], 5-methyl-1,2,4-triazole (3,4-b)benzothiazole [Beam] , 3'-isopropoxy-2-methylbenzanilide [Mepronil (
MepronN)), 2-isopropylphenyl-N
-Methyl carbamate [old PC], 3,5-dimethylphenyl-N-methylcarbamate, dimethyl [1,2-phenylene)bis-(iminocarbocchi oil)]biscarbamate [Topgin n], N'-(2- methyl-4-chlorophenyl)N.

N-dimethylformamidine [chlorozenamidine]
, S-methyl-N-(methylcarbamoyloxy)thioacetimidate, 1,2-dibromo-3-chloropropane, N-(trichloromethylthio)-4-cyclohexene-1,2-dicarbosiimide, cis-N-( (1-dichloromethyl)thio)-4-cyclohexene-1,2-dicarboximide [cabutane], cis-N-((1,1,2,2tetrachloroethyl)
Thio) 4-cyclohexene 1,2-dicarboximide [Guyfortan], herbicides include 4-2,4-dichlorobenzoyl), 3-dimethyl-5-pyrazolyl-P-toluenesulfonate [Sanbird] methyl 5-(2,4-dichlorophenoxy)-2-nitrobenzoate [Modalan (
), 1-(α,α-dimethylbenzyl)-3-(P-tolyl)urea [Dimu
ron)], α-(2-naphthoxy)propion-anilide [tlribest), 3-(
3,4-dichlorophenyl)-1,1-dimethylurea (Karmex), 2-chloro-4
, 6-bis-(ethylamino)-1,3,5-1-riazine (Simazine), 1-(4-
difluorochloromethylcapto-3-chlorophenyl)
-3,3-dimethylurea (KUE), 2.4-dichlorophenyl-4-nitrophenyl ether, 2.4.6-1-dichlorophenyl-4-nitrophenyl ether, 3.4-dichloropropion AniRide CDCP^],
2-Methylthio-4,6-bis(ethylamino)-3-
Examples include triazine [simetrine], 3-isopropyl-2,1,3-benzothiadiazinone-(4)-2,2-dioxide [pentacine], and others that are essentially sparingly soluble in water.

It is also possible to use one type of these, or to use two or more types, and to prepare a preparation by mixing easily water-soluble active ingredients.

The blending ratio of the agricultural chemical raw material in the wettable powder is preferably 20 to 98 parts by weight, more preferably 30 to 85 parts by weight. In the present invention, the highly concentrated bulk wettable powder that can achieve remarkable effects such as water compatibility and disintegration properties is preferably 50 parts by weight or more, especially 60 to 8 parts by weight.
5 parts by weight.

Mineral powder can also be blended into the hydrating agent if necessary. Specifically, mineral powders include waxite, talc,
Examples include kaolin, calcium carbonate, bentonite, silica powder, limestone powder, acid clay, diatomaceous earth powder, gypsum, pumice powder, shell powder, mica powder, and colloidal hydrated sodium silicate.

When blending mineral powder, the blending ratio of mineral powder in the wettable powder is 0 to 60 parts by weight, preferably 2 to 50 parts by weight.

In addition to the above components, a surfactant such as polyoxyethylene alkylaryl ether may be added as a wetting agent if necessary.

In carrying out the present invention, in addition to the agricultural chemical ingredients, (11 to (4)
), other molecules and agents, water-soluble thickeners, anti-foaming agents, anti-decomposition agents, anti-agglomeration agents, etc. can be added as necessary.

As the dispersant, in addition to the compounds (1) to (4) already described, a nonionic surfactant and/or anionic surfactant may be used. Examples of such nonionic surfactants and/or anionic surfactants include polyoxyethylene (hereinafter referred to as POE) alkyl (carbon number 6 to
22) Ether, POE alkyl (4 to 18 carbon atoms) phenol ether, polyoxypropylene polyoxyethylene (block or random) alkyl ether, P
OE phenylphenol ether, POE styrenated phephenol ether (OE) nonionic surfactants such as ribenzylphenol ether, alkylbenzene sulfonate, alkyl sulfonate, POE alkyl sulfonate, POE alkyl phenyl ether sulfonate, POE alkyl phenyl ether phosphate ester salt, POE phenyl phenol ether sulfone fi salt, POE phenyl phenol ether phosphate ester salt, naphthalene sulfonate, PoE tribenzyl phenol ether sulfonate, POE tribenzyl phenyl phenol ether phosphate ester salt Anionic surfactants such as These can be used alone or in combination. Its content in the composition is 0
~20ffiffl percent, preferably 1 to 10 weight percent.

Natural, semi-synthetic and synthetic water-soluble thickeners can be used as water-soluble thickeners. Natural mucilages include xanthan gum and xanfro derived from microorganisms, pectin derived from plants,
Semi-synthetic mucilage materials include methylated products, carboxyalkylated products, hydroxyalkylated products (including methyl cellulose, carboxymethyl cellulose, hydroxymethyl cellulose, etc.) of cellulose or starch derivatives, etc., and synthetic mucilage materials include polyamide, gum arabic, guar communis, etc. Specific examples include acrylates, polymaleates, and polyvinylpyrrolidone. The water-soluble thickener is about 0-3.0% by weight of the composition, preferably about 0.05-0.0% by weight of the composition.
It is blended in an amount of 5% by weight.

Antifoaming agents may optionally be included up to about 2% by weight to prevent foaming during formulation, and antidegradants may be included up to about 7% by weight to prevent degradation, particularly during storage of organophosphorus biocides. is preferred. The anti-foaming agent is not particularly limited and any anti-foaming agent may be used, but specific examples include polypropylene glycol and silicone oil.

Examples of the decomposition inhibitor include epichlorohydrin, phenylglycidyl ether, allylglycidyl ether, and the like.

In addition, depending on the situation, an anti-aggregation agent (for example, polyoxyethylene-polyoxypropylene block polymer), an anti-drift agent (for example, sorbitol), etc. may be added to the solid biocide within a range that does not impair the effects of the present invention. can.

The method for preparing the pesticide dispersion slurry may be to disperse the dry-pulverized raw material using the dispersant described in the present invention, or to obtain particles with even smaller particle sizes, grinding by a wet-pulverization method such as a sand grinder. Of course, there is no problem with slurry.

Conventionally, granular wettable powders have been obtained by dry tableting, or by adding a dispersant and an appropriate amount of water to a mixture of agrochemical powder, or a mixture of agrochemical powder and an inorganic mineral powder. , further mixed with adjuvants if desired, and then wet granulated by transfer granulation, fluidized bed granulation, extrusion granulation, etc. However, the water compatibility when added to water is It is significantly inferior to the product of the present invention in terms of dispersibility, etc. Furthermore, when the agrochemical dispersion slurry is granulated using a co-current spray dryer, the bulk density, particle size, and other shapes are inferior to the products of the present invention.

〔Effect of the invention〕

According to the present invention, it is possible to obtain a granular wettable powder that contains a high concentration of active ingredients, has excellent hydration properties and disintegration properties, and has good suspension stability. In addition, since the particle size is large, it is easy to store and transport, and there is less scattering during handling. In particular, the initial dispersibility of high-concentration agricultural chemical hydrating agents is improved. The effect of the dispersant of the present invention is remarkable in systems where the amount of agricultural chemical ingredient is 90% by weight or less, particularly 50 to 85% by weight. In this case, the amount of dispersant added is 1/2 to 1/3 that of wet granulation method etc. 3-15
Weight % is sufficient.

Further, the granular pesticide of the present invention self-disperses immediately after being added to water, and provides a diluted suspension with no change in particle size from the particle size when preparing the pesticide-dispersed slurry.

〔Example〕

The present invention will be specifically explained below using Examples and Comparative Examples.

Example 1 A slurry was prepared by adding 10 parts by weight of soda salt of a copolymer of acrylic acid and maleic anhydride, 10 parts by weight of Glauber's salt, and 60 parts by weight of water to 80 parts by weight of pre-pulverized cabtan raw material,
Spray nozzle diameter 2.5mm, spray pressure 15kg/cm
2. Powder was prepared using a countercurrent spray dryer under conditions of a hot air inlet temperature of 200°C and an exhaust air temperature of 110°C.

Example 2 80 parts by weight of pre-pulverized cabtan raw material, 20 parts by weight of soda salt of a copolymer of acrylic acid and polyoxyethylene methacrylate, 10 parts by weight of white carbon, and 7 parts by weight of water.
0 parts by weight was added to prepare a slurry, and the spray nozzle diameter was 1.
2III11, a spray pressure of 40 kg/Cll1z, a hot air inlet temperature of 180°C, and an exhaust air temperature of 100°C, using a countercurrent spray dryer to prepare powder.

Example 3 10 parts by weight of formalin condensate of sodium salt of naphthalene sulfonic acid was added to 80 parts by weight of the pre-pulverized guifortan raw material,
A slurry was prepared by adding 10 parts by weight of clay and 60 parts by weight of water, using a spray nozzle diameter of 1.5 mm and a spray pressure of 20 kg/
Powder was prepared using a countercurrent spray dryer under the conditions of cre2, hot air inlet temperature of 180°C, and exhaust air temperature of 100°C.

Example 4 10 parts by weight of a copolymer of styrene sulfonic acid soda salt and xylene sulfonic acid soda salt, 10 parts by weight of Na tripolyphosphate,
10 parts by weight of clay, 10 parts by weight of white carbon, 6 parts by weight of water
0 parts by weight was added to prepare a slurry, and the spray nozzle diameter was 2.
5++v+, a spray pressure of 30 kg/C112, a hot air inlet temperature of 250°C, and an exhaust air temperature of 110°C, using a countercurrent spray dryer to prepare powder.

Example 5 10 parts by weight of sodium lignin sulfonic acid formalin condensate salt, 20 parts by weight of clay, and 80 parts by weight of water were added to 70 parts by weight of Topgin M raw material, and the mixture was wet-pulverized with a sand grinder for 2 hours to obtain an average particle size of 3. A 5μ slurry was prepared.

Spray nozzle diameter 3.0mm, spray pressure 30kg/am
Powder was prepared using a countercurrent spray dryer under conditions of a hot air population temperature of 200°C and an exhaust air temperature of 120°C.

Example 6 80 parts by weight of guifortan raw material, 10 parts by weight of a copolymer of styrene sulfonic acid soda salt and maleic anhydride, 10 parts by weight of clay, and 80 parts by weight of water were crushed with a sand grinder for 2 hours, A slurry having an average particle size of 3.0 μm was prepared. Spray nozzle diameter 1.5mm+, spray pressure 40k
g/cm”, hot air inlet temperature 200℃, exhaust air temperature 11
Powder was prepared using a countercurrent spray dryer at 0°C.

Comparative Example 1 A slurry was prepared by adding 10 parts by weight of a soda salt of a copolymer of acrylic acid and maleic anhydride, 10 parts by weight of Glauber's salt, and 60 parts by weight of water to 80 parts by weight of a pre-pulverized carbantane raw material, and a slurry was prepared using a spray nozzle. Diameter 1, 5mm, spray pressure 50kg/c
Powder was prepared using a co-current spray dryer under the following conditions: m2, hot air inlet temperature of 180°C, and exhaust air temperature of 100°C.

Comparative Example 2 70 parts by weight of the pre-pulverized Topgin M raw material, 10 parts by weight of styrene sulfonic acid sodium salt and xylene sulfonic acid sodium salt copolymer, 10 parts by weight of clay, 1 part by weight of white carbon
0 parts by weight and 10 parts by weight of Na tripolyphosphate were added to prepare a slurry, and the spray nozzle diameter was 0.8 mm and the spray pressure was 5.
0kg/cm2, hot air inlet temperature 200″C2 exhaust air temperature 1
Powder was prepared using a countercurrent spray dryer at 10°C.

Comparative Example 3 80 parts by weight of difortan raw material, 10 parts by weight of copolymer of styrene sulfonic acid soda salt and maleic anhydride, 80 parts by weight of water
Parts by weight were added and ground for 2 hours using a sand grinder to prepare a slurry with an average particle size of 2 μm. Spray nozzle diameter 0
．． 6 ms+, a spray pressure of 25 kg/cm'', a hot air inlet temperature of 200°C, and an exhaust air temperature of 110°C, using a countercurrent spray dryer to prepare powder.

Comparative Example 4 10 parts by weight of soda salt of a copolymer of acrylic acid and maleic anhydride, 10 parts by weight of Glauber's salt, and 20 parts by weight of water were added to 80 parts by weight of pre-pulverized cabtan raw material, and kneaded to form a screen of 0.81. The mixture was granulated using an extrusion type granulator equipped with a granulator, sized to 20 to 32 meshes, and dried at 30°C to obtain a granular product.

Comparative Example 5 70 parts by weight of the pre-pulverized Topgin M raw material, 10 parts by weight of a copolymer of styrene sulfonic acid soda salt and xylene sulfonic acid soda salt, 10 parts by weight of clay, 10 parts by weight of white carbon, and 30 parts by weight of water. Add and knead to 0.8mm
It is granulated using an extrusion type granulator equipped with a screen of 20 to 3
The particles were sized into 2 meshes and dried at 30°C to obtain granular products.

Comparative Example 6 10 parts by weight of formalin condensate of sodium salt of naphthalene sulfonic acid was added to 80 parts by weight of the pre-pulverized difortan raw material,
Add 10 parts by weight of clay and 30 parts by weight of water and mix to make 0.8m.
Granulate with an extrusion type granulator equipped with a screen of 20
The particles were sized to ~32 mesh size and dried at 30°C to obtain granular products.

do6 in Examples 1 to 6 and Comparative Examples 1 to 3 above. ?
Table 1 shows the values of Oxp-0-40xp O-R2X and O-60.

Table 1 Examples 1 to 6 and Comparative Examples 1 to 6 were evaluated for self-dispersibility, hydration, and suspension stability as follows. The results are shown in Table 2 along with the particle size, bulk density, and presence or absence of dusting.

(2) Fill a framed cylinder with a self-dispersibility (disintegration) rating of 250- to 125-degree hard water, and gently add 1.2 g of the sample prepared in the above manner.

At the same time as observing self-dispersibility, the number of times the cylinder is overturned once every 2 seconds is counted until all the input particles are disintegrated and dispersed.

The evaluation criteria for self-dispersibility are as follows.

4 Disperses immediately without forming secondary aggregates.

3 No secondary agglomerates are formed, but 50% of the input particles are not dispersed.

-2 No secondary agglomerates are formed, but more than 80% of the input particles are not dispersed.

1 Aggregation occurs between particles and 100% of the input particles are not dispersed.

(1) Put 100° hard water into a beaker with hydration property of 100°, gently add 1.0 g of the sample prepared in the above manner, and measure the time required for the powder to submerge.

■ Precisely weigh the suspension stability evaluation sample in a beaker and add it to 501II 3 degree hard water at 20℃.
1 and mix and disperse well. Transfer it to a 250 ml framed cylinder, add 3 degree hard water at 20°C to make 250 ff1l, let stand for 15 minutes, shake vigorously 30 times per minute, and let stand for 5 minutes. Next 25-
Place a whole pipette into the solution, keep its tip in the center of the solution, gently take out the sample solution, filter it using a glass filter, dry the residue at 105℃ for 4 hours, and calculate the suspension rate using the formula below. demand.

A: Weight of the sample accurately weighed at the beginning B: Dry residue weight of collected test solution Table 2

Claims (1)

[Scope of Claims] 1. A method for producing granular agricultural chemicals, which comprises countercurrently spray-drying a concentrated dispersion slurry containing a water-insoluble agricultural chemical powder under the following conditions (i) and (ii). (i) 6.8≦de^0^. ^7^0×P^-^0^.
^4^0×μ^0^. ^2^2×σ^0^. ^6^0 {de: Nozzle diameter (mm) P: Pressure (kg/cm^2) μ: Slurry viscosity (cps) σ: Slurry surface tension (dyn/cm)} (ii) Spray nozzle diameter 0.5~ 4.0mm, spray pressure 5-250kg/cm^2 (pressure nozzle) Hot air inlet temperature 150-300℃ Exhaust air temperature 60-120℃