HU201483B - Method for producing agent granules of plant protective dried by atomization - Google Patents

Description

FIELD OF THE INVENTION The present invention relates to the preparation of solid pesticidal compositions in the form of granules which are readily dispersible in water.

Both solid and liquid formulations of the active ingredient are marketed for agricultural use. The formulations are used to make water sprays with water. The nature of the preparation depends primarily on the physical properties of the active substance.

So-called wettable powders (WPs), which are water dispersible powders, are widely used. The user mixes the powder with water and knots must be prevented by pre-kneading. Such powders must be extremely fine-grained (particle size about 5 μm) for proper buoyancy. However, this results in unpleasant dust formation and poor flow properties when used, resulting in incomplete emptying of the container and inaccurate dosing of the powder.

Because of the above disadvantages, high concentration suspensions (SC or flowable), which are liquid preparations, are often used. Although these formulations are easier to process into spray liquors, there are problems with precipitation after a longer shelf life and problems with the placement of empty liquid containers.

More or less coarse-grained granules are well-used because they are dust free, easy to pack and dispense, and are rapidly and completely soluble or dispersible in water, thereby preventing spray nozzles from spraying.

It is known that water-dispersible granules can be formed in suitable equipment by the addition of a small amount of liquid (water or water and an organic solvent) with mixing and roller movement of the material to be granulated.

Alternatively, in a granulating drum, the granulating fluid is added to the material to be granulated in such a way that the equilibrium moisture content of the material is exceeded and the resulting product is dried to or below the equilibrium moisture content.

Water dispersible granules can be prepared by tabletting powder blends or compressing powder blends. Extrusion of the moistened powder mass followed by drying can also be used to produce water dispersible granules.

The preparation of water-dispersible granules by the fluidization process is also known. In the latter, the finely divided material is sprayed with an aqueous solution containing a binder.

Finally, spray drying of aqueous formulations of the active ingredient (using suitable excipients) is also a preferred method of converting large amounts of the active ingredient into small granules. The technological details of the latter method are reviewed, for example, in K. Masters, Spray Drying Handbook, 4th Edition, London, 1985.

The disadvantage of all known procedures is that they are generally difficult to control, as many factors need to be taken into consideration at the same time. Often too loose material is formed which has a bulk density of 2 and therefore occupies a relatively large packaging volume. In addition, granules also tend to form dusts and are not always dispersible or soluble in aqueous media because they have a density less than that of water. It is also disadvantageous that the granules often have very different particle size distribution.

Recovery of heat-sensitive active pharmaceutical ingredients from aqueous concentrates containing ammonium salts, in particular ammonium bicarbonate, known from German Patent No. 19 32 583.

However, tests of the applicability of this process for the preparation of pesticide granules have shown that the aforementioned small amounts of ammonium salts are not feasible because, as described in German Patent Specification 19 32 583 cited above, instead of the desired dust-free balls a fine powder is formed.

It also appeared that spray-drying further reporting technical measures were required when using more than 1 to 2% by weight of bicarbonate, since in this case the appropriate amount of ammonium had to be removed from the air leaving the dryer.

SUMMARY OF THE INVENTION It is an object of the present invention to provide dispersible active ingredient granules for plant protection purposes, preferably by spray-drying aqueous excipient-containing active ingredient concentrates which are uniform in particle size, i.e. narrow, dense, solid and transportable and non-volatile.

According to the invention, the object is solved by adding less than 2% by weight of ammonium bicarbonate to the active compound concentrate. The appropriate good results are affected by the nature and amount of excipients. Spray-drying of aqueous formulations of the active ingredient containing at least 10% by weight of the lignin sulfonate as an excipient, in addition to the ammonium bicarbonate, has proven particularly advantageous. Preferred are lignin sulfonic acids of high quality, preferably of high molecular weight and having a degree of sulfonation (molar base unit molar sulfonic acid relative to phenol) of less than about 0.8, preferably 0.3 to 0.5. These products can be prepared, for example, by partial desulfonation of the material formed in the production of sulfide cellulose.

The effect of the process according to the invention is that unlike relatively small, single-sided or polygonal bound granulate beads or amorphous powder produced without ammonium bicarbonate, which is formed by too much ammonium bicarbonate due to too much hydrogen carbonate the granules are particularly spherical and have a very uniform particle size distribution and are completely dust-free.

Surprisingly, the granules produced according to the invention have a very excellent disintegration in the medium of vi-2HU 201483 Β zcs. show properties. The granules are practically completely disintegrated in a short time with the formation of a fine dispersion.

In contrast to the effervescent tablets, the granules themselves, as can be seen, contain only a very small amount of ammonium salt, since the ammonium salt, like the baking powder process, is practically completely decomposed by heating. Granules with a smooth surface externally are assumed to be porous internally due to gas formation.

Aqueous spray concentrates of the invention generally contain less than 1% by weight, and for practical purposes, contain about 0.7% by weight of ammonium bicarbonate.

Typical drug concentrates generally contain up to 75% by weight of water, up to 50% by weight of active ingredient, and up to 30% by weight of lignin sulfonic acid salt.

In addition to the above compositions, the compositions may also contain fillers, thickeners, or carriers, non-volatile diluents, colorants, binders, and other customary excipients.

Insecticides, fungicides, herbicides, growth regulators, fertilizers which can be spray-dried alone or in combination with carriers or other auxiliaries are suitable as active ingredients in the present invention. Liquid or low melting point materials may also be used, but solid base materials melting above 100 ° C are preferred.

For example, the following active compounds may be used.

1. Fungicides

2-methoxycarbonylaminobenzimidazole, zinc [N, N'-ethylene bis (dithiocarbamate)], 3- (3,5-dichlorophenyl) -5-methyl-5-vinyl-1,3-oxazilidin-2 4-dione;

2,4,5,6-tetrachlorethylene isophthalate-dinitril-,

N-trichloromethylthiotetrahydro-phthalimide, sulfur, 1,2-bis (3-ethoxycarbonyl-2-thioureido) benzene, tetramethylthiuramide sulfide,

1- (2- (2,4-dichlorophenyl) -2- (2-propenyloxy) ethyl-1H-imidazole,

2.4-dichloro-6- (2-chloroaniline) -1,3-triazine,

2. Herbicides

3-Isopropyl- (1H) -benzo-2,1,3-thiadizin-4-one-2,2-dioxide

3.5-dibromo-4-hydroxybenzomtril,

5-amino-4-chloro-2-phenyl- (2H) -pyridazinone,

2-chloro-4-methylamino-6-isopropylamino-1,3,5-triazine,

2-trifluoromethyl-4,5-dichlorobenzimidazole,

N- (4-chlorophenyl) -N'-methyl-N'-butin-1-yl-3-urea,

N-methoxymethyl-.alpha.-chloroacetamide-2,6-diethyl-anilide,

3-amino-2,5-dichlorobenzoic acid,

N- (3,4-dichlorophenyl) -N'-methoxy-N'-methylurea,

3-cyclohexyl-5,6-trimethyl-uracil,

3,7-dichloro-8-quinolinecarboxylic acid,

7-chloro-3-methyl-8-quinolinecarboxylic acid

3. Insecticides 1,2,3,4,4-10,10-hexachloro-6,7-epoxy-1,2,3,4,4-10,10hexachloro-6,7-epoxy-1,4,4a, 5,6 , 7,8,8a-octahydro-4

- (endo-exo) -6,8-dimethanonaphthalene, 1,2,3,4,5,6,7,8,8-octachloro-3a, 4,7a-tetrahydro-4,7

methano phthalate,

6-chloro-3,4-xylyl-N-methylcarbamate,

1-naphthyl N-methylcarbamate,

4-benzothienyl N-methylcarbamate,

2,2-dimethyl-1,3-benzodioxol-4-yl-N-methylcarbamate,

4-chloro-phenyl-2,4,5-trichlorophenyl sulfone,

4-chlorophenyl-2,4,5-trichlorophenyl-azoszulfid,

2- (p-tert-butyl-phenoxy) -1-methylethyl-2-chloro-ethylsulfite,

6-methyl-konixalin-2,3-dithiocarbonate.

The process according to the invention is particularly advantageous for the preparation of granules containing the herbicide chlorideazone. The following example illustrates the procedure.

EXAMPLE 1 Parts of chloridazone, 2 parts of alkyl arylsulfonate, 2 parts of ammonium bicarbonate and 30 parts of lignin sulfonic acid sodium salt are mixed, dispersed in an equal amount of water and the resulting slurry is ground in a stirred ball mill. Dried in a spray tower at 160 ° C with the introduction of drying air, granules are formed which rapidly and completely disperse. This results in a good buoyancy in water of more than 80% and the spray can be applied unhindered.

Comparison

If the procedure described in the example is followed but ammonium bicarbonate is omitted, the buoyancy under the same conditions is substantially less than 80%. If the sprayer is filled directly, that is, without filtering, malfunctions occur after a short time due to clogging of the sprayer holes. thus, it is not possible to apply the spray evenly.

The surface of the hollow spheres formed was broken and the sphere wall fell.

b) When 1.6 parts by weight of ammonium bicarbonate are added to the mixture, well-formed hollow spheres are formed which are completely dispersed in water and the spray liquid can be uniformly applied.

c) When 4.5 parts by weight of ammonium bicarbonate are added to the mixture, the gas formed during drying degrades the hollow spheres to obtain a significant amount of powder.

EXAMPLE 2 One part by weight of chlorideazone, 1.5 parts by weight of alkylaryl sulphonate, 1.5 parts by weight of ammonium bicarbonate, 17 parts by weight of sodium sulphate are dispersed in water equal to the weight of the mixture and

Grind the slurry in a ball mill equipped with a stirrer. By spray drying at an inlet temperature of 160 ° C, granules are obtained which are rapidly and completely dispersible in water and the resulting spray liquid can be uniformly applied.

In the above composition, the amount of sodium lignin sulfonate can be increased in equal proportions instead of sodium sulfate.

EXAMPLE 3 One part by weight of chlorideazone, one part by weight of ammonium bicarbonate, 17 parts by weight of kaolin and 30 parts by weight of sodium ligand sulfonate is added and 70 parts by weight of water are added. Grinding and spray drying at an inlet temperature of 180 ° give granules that are well dispersible in water.

Claims (5)

PATENT CLAIMS 1. A process for making water dispersible active ingredient granules for plant protection purposes. 70 to 100% by weight based on the total weight of the mixture of 50 to 70 parts by weight of active ingredient, 1.5 to 4 parts by weight of alkylaryl sulfonate, 20 to 60 parts by weight of sodium lignin sulfonate and ammonium bicarbonate, and optionally customary inert excipients. spray drying the aqueous concentrate, wherein the aqueous concentrate of the mixture containing 1-4 parts by weight of ammonium bicarbonate in which the ammonium bicarbonate is up to 2% by weight is granulated. 2. A process according to claim 1, wherein the concentrate contains up to 1% by weight of ammonium bicarbonate. The process of claim 1, wherein the granules are air dried at an inlet temperature of 120-220 ° C. 4. A process according to claim 1 wherein the active ingredient is chloridazone. The process of claim 1, wherein the total water content of the active compound concentrate is up to 75% by weight.