IL30412A - Storable highly concentrated pesticides and process for their manufacture - Google Patents

Description

STORABLE HIGHLY CONCENTRA ED PESTICIDES AND PROCESS FOR THEIR MANUFACTURE y nrn ,η¾οπκ> n»¾n*33 o* ΤΡΉΒ BV D » ? Storable highly concentrated pesticides and process for their manufacture Case Fw 5¾25 Commercial pesticides in the form of wettable powders - for actual use in the form of their aqueous suspension - are as a rule manufactured by repeated dry grinding of the active substance and carrier substances as well as further additives such as grinding aids and the like, and subsequent mixing of the powder with wetting agents and/or dispersing agent. The intensive grinding is necessary in order to achieve a material which meets the international standards as to the storability and suspending properties of such agents.

Wettable powders manufactured in the above manner have a maximum content of the active substance which is predominantly determined by the physical properties of the latter, as can readily be seen if one takes into account the temperatures, electrostatic charges of the material being ground, and similar factors, which arise on dry grinding.

Fw 5¾25 As an object of the present invention, a process for the manufacture of storable highly 'concentrated pesticides has now been found which is characterised in that a preferably aqueous suspension of the active substance is ground to a particle fineness of less than about k f*> ( = 350 mesh) in the presence of a surface-active substance as well as optionally of an inert substance or carrier and optionally of further formulation additives (wet grinding), that the material is spray-dried, appropriately by means of two-substance nozzles, under a dry gas at 60 - 200°C , preferably 6o - 120°C, and an atomisation air pressure of 2 - 6 atmospheres excess, preferably 3 · 5 - 5 atmospheres excess, or by centrifugal atomization by means of a vaned wheel and that subsequently about 0 , 2 - 3 of a highly disperse carrier as well as further formulation additives for highly concentrated wettable powders are optionally admixed to the dry material* Suitable active substances for the present process are all insecticides, acaricides, herbicides, fungicides or the like which can be suspended and are hence amenable to wet grinding* Such products are frequently not well suited to dry grindin because of their softness.

Another object of the invention are new compositions of matter in the form of storable wettable powder pre-concentrates comprising about 90 % and above of a pesticide active substance in conjunction with about 0.05 to 5 % of a surfactant, and optionally a carrier for the remainder in a particle size of < 4 |fc ( ■ 350 mesh).

F 5¾25 The following may for example serve as surface-active substances: dried sulphite cellulose waste lye, sodium dinaphthylmethane-disulphonate , sodium dibutylnaphthalene-eulphonate, partially saponified polyvinyl acetates, sodium oleylmethyltauride , alkylbenzenesulphates , alkylbenzene-sulphonates, alkyl sulphates, alkyl sulphonates, sodium salts of sulphosuccinic acid esters or of alkylphenylpoly-glycol sulphuric acid esters, dextrins, blood albumins, and skimmed milk powder.

Suitable carriers for the present process are for example kieselgur, clays, bentonites and highly dispersed silica.

The addition of small quantities, that is to say about 0.05 - 5 » of surface-active substances facilitates grinding, reduces the agglomeration of the grinding suspension and facilitates atomisation into smaller droplets, thereby reducing the drying time. The drying path of the droplet is therefore short, that is to say the drying tower can be correspondingly low.

Grinding mills, which are used in the form of agitator mills, sand mills or ball mills, are suitable for. the wet grinding of the active substance suspension, in accordance with the invention, down to a particle fineness of .

The fine dry material from the spray drying, which according to the invention is obtained with a high content of active substance, is characterised in that its fine Fw 5425 coated with particles are each gncapstrltrted by the surface-active material used. It is either a pre-concentrate - having an active substance content of 9 % and above - for use in the manufacture of a wettable powder in, for example, cross-beater mills or the like, whilst further adding locally occurring economically easily accessible inert substances of the most diverse nature, for example kieselgur or quartz flour as well as further, surface-active, substances, for example wetting agents or dispersing agents, or it is already such a wettable powder whose active substance content of about 65 - 8θ % is conspicuously high.

In this way the present invention solves the problem of making available, in technically less developed areas, highly concentrated starting mixtures of pesticides which after appropriate addition of formulation additives, which are in each case locally accessible without high demands as to their characteristics, and after grinding in ordinary cross-beater mills, yield wettable powders.

These can have a far higher active substance content than is the case with pesticides obtainable in the usual manner by dry grinding.

As has been mentioned it is also possible, as can be seen from the examples, to manufacture wettable powder formulations directly by the process according to the invention.

- - Fw 5^25 & The process products having an active substance content of 90 - 99· 5 96» and the wettable powders manufactured therefrom, are storable for 2 - 3 months at 50°C , which as a rule corresponds to a storability of 2 - 3 years at normal temperatures. They fulfil the standards set up by the World Health Organisation.

Quite generally, the so-called wettable powders manufactured from the pre-concentrates of the invention with grinding on a simple cross-beater mill show a high active substance stability, as emerges from a comparison, given later, with a wettable powder maufactured by very fine grinding in the conventional dry manner, which contains the same quantities of formulation components.

The process according to the invention will be explained in relation to the schematic sketch. drawing Description of Process (see akft h) The plant protection active substance is mixed via a metering disc (l), with addition of an approxi-mately 3-fold quantity of water, with a surface-active agent as well as with an inert substance (2){ the mixture . is pumped into a ball mill (3) for wet grinding, is collected from there in a stirred container (4) and is fed via the pump (5) to the spray nozzle or vaned wheel for centrifugal atomization (6)· Fw 5¾25 For spray drying, the fresh air drawn in by means of a fan ( 7) is directly heated to 60 - 200°C, preferably 60 - 120°C, by means of an oil burner ( 8) and is passed to the drying tower (lO). The wet material is sprayed from a pipeline ( 9 ) by means of the two-substance nozzle •OV- two-gubataitee—a«-B¾4.-e , using compressed air at 2 - 6 atmospheres excess, preferably 3 · 5 - 5 atmospheres excess, or a vaned wheel for centrifugal ' atomizetion ( 6 ) and is passed through the drying tower ( 10) , with dry gas passing in the same direction.

The dry material is separated off at the base of the drying tower (lO) and by means of cyclones (ll) and is fed to the filling operation ( l3) via the post-mixer ( 12) Example 1 A 20 strength aqueous suspension of 99 * 7 parts by weight of pentachlornitrobenzene and 0.3 parts by weight of sodium oleylmethyltauride is ground wet in an agitator mill, sprayed by means of a two- substance displacement nozzle, using compressed air at - 5 atmospheres excess, and dried by means of air at 110 - 120°C.

Fw 5425 Thereafter 0.2 - 0. 3 parts by weight of highly disperse silica are admixed.

Particle size distribution: 0. 3 % 4.0 % > 33 a 80.0 % 20 - 33^ 16.0 % After a storage of 3 months at 50°C the wettable powder pre-concentrate does not show any agglomerations.

The total floatability of the 75 % strength wettable powder manufactured therefrom, that is to say of the total mixture, is 80 % after 30 minutes. The mixture has the following composition: 75.4 parts by weight of the above pre-concentrate ( 99.7 % strength) 3 " " " of sodium oleylmethyltauride 21 .6 " " " of kieselgur A commercially available wettable powder containing the same active substance at a concentration of 75 % requires the constituents of the formulation to be ground dry 2 - 3 times on high performance mills.

Example 2 A mixture of 96 parts by weight of linuron Fw 5¾25 2 parte by weight of kieselgur 1»¾5 " " " " sodium naphthalenesulphonate 0.5 " " " " partially saponified polyvinyl acetate, and 0.05 "■ " " " sodium oleylmethyltauride , processed into a wettable powder pre-concentrate according to Example 1, by wet grinding and spray drying at 120°C, shows 99.4 to have a particle size Moisture content! 0.2 tt.

The further formulation of the above pre-concentrate may be effected to give an 80 % strength wettable powder by adding further quantities of inert substances and wetting agents and grinding the whole in a cross-beater mill. The total floatability of the wettable powder is 71 %· It has the following composition: 83.2 parts by weight of the above pre-concentrate (96 % strength) 0.05 " " " " sodium oleylmethyltauride 1.0 " " " " sodium hydrogen carbonate 6.0 " " " " sodium dinaphthylmethanedi- sulphonate 1,5 11 M ti 11 partially saponified polyvinyl acetate 8.25 " " " " finely disperse silica Fw 5¾25 Example 3 A mixture of 80.0 parts by weight of linuron 9*0 parts by weight of kieselgur «¾ " " " " sodium naphthalenesulphonate 1.5 " " " " partially saponified polyvinyl acetate 0.1 " " " " sodium oleylmethyltauride is subjected to wet grinding and spray drying at 120°C in accordance with Example 1 and subsequently mixed with parts by weight of highly absorptive silica. The total floatability of the product is 70 %· The particle size of the process product is 99· 7 % <¾4U.

The process product can be directly used as a wettable powder.

Hitherto a linuron preparation could only be ground dry with active substance contents of up to 50 %, since the grinding plant otherwise became smeary.

Example ½ 92.50 parts by weight of 3 Fw 5¾25 * 6.05 parts by weight of Kieselgur 1 . 25 " " " " partially saponified polyvinyl acetate 0. 20 " " " " Na salt of a naphthalenesul- phonic acid are processed as in Example 1 . In this case the addition of a carrier substance after spray, drying is unnecessary.

The particle size of the process product is 99 · % An 80 % strength wettable powder can be formulated from the dry substance by adding highly disperse silica, sodium hydrogen carbonate and sodium naphthalenesulphonate whilst grinding in a beater mill. The total floatability of the wettable powder is 86. 9 %· I has the following composition: 86. 7 parts by weight of pre-concentrate ( 92. 5 % strength) 3.0 " " " " partially saponified polyvinyl acetate 2.0 " " " " sodium hydrogen carbonate 0. 5 " 11 " " sodium alkylnaphthalenesulphonate 7.8 " » " " finely disperse silica A commercial monolinuron preparation shows an active substance content of 5 % .

Example 5 92 parts by weight of triphenyl tin acetate (C^H^) ^.Sn.O.OC .CH^ 6 » " " " chalk Fw 5¾25 ^ are subjected to wet grinding and spray drying at 100°C in accordance with Example 1. The a'ddition of an inert substance after spray drying is unnecessary. The particle size of the process product is 98. k % ^^ » and the particle size of the wettable powder after adding 0.3 parts by weight of highly disperse silica and storing for 3 months at 50°C is 98 % <44 .

COMPARISON EXPERIMENT Compositions: a) Wettable powder obtained from the pre-concentrate b) Wettable p according to the invention 65 parts by weight of triphenyl tin acetate pre- 60 parts by w concentrate (see above) tt II II manganese-ethylene-bis- 20 II II dithiocarbamate .75" It II sodium naphthalenesulphonate II II II sodium alkylnaphthalenesul- phonate II II II partially saponified it n polyvinyl acetate ¾.75" it n chalk 8.5 " II 0.50" highly disperse silica 0.5 " Fw 5¾25 The total floatability of each lettable powder is 82 - 85 %, The lose of active substance ( % absolute) after 3 months' storage at 50°C is: Formulation a Formulation b Triphenyl tin acetate Manganese-ethylene-bi dithiocarbamate Example 6 92.Ο parts by weight of endosulfan 7.0 " " " " kieselgur 0.6 " " " " sodium naphthalenesulphonate 0, " " " 11 partially saponified polyvinyl ace are subjected to wet grinding and spray drying in accordance with the process of Example 1* Thereafter 2,0 parts by weight of highly disperse silica are added to the dry material* The wettable powder pre-concentrate thus obtained is still freeflowing after 2 months at 50°C. It is suitable, in the formulation given below, for the manufacture of a wettable powder by grinding the formulation constituents in a cross-beater mill.

Fw 5^25 83.0 parte by weight of the above pre-concentrnte .3 II I I II I I silica 2.2 II 1» II tl ammonia sulphate 1.5 II II II II sodium naphthalene sulphonate 3.0 H II • 1 II partially saponified polyvinyl Total floatability of the wettable powder: 8t,5 %.

Example 7 96.Ο parts by weight of 3» 3' -methylene-bis(tetrahydro- k , 6-dimethyl-2-N- 1,3, -thiadiazine- 2-thione) H H 3.5 parts by weight of kieselgur 0*5 " " " " sodium naphthalenesulphonate are subjected to wet grinding and spray drying in accordance with the process of Example 1. A 75 % strength wettable powder is obtained by mixing the pre-concentrate thus obtained with formulation additives (polypropylene glycol, sodium naphthalenesulphonate , further quantities of kieselgur and silica). Its total floatability is 85 %i after 2 months' storage at 50°C it is 80 %.

Fw 5¾25 Example 8 80.O parts by weight of the active substance of Example 7 2.0 " partially saponified polyvinyl acetate 7.0 " sodium naphthalenesulphonate 0. 5 " polypropylene glycol IO. 3 11 kieselgur are subjected to the process according to Example 1 by wet grinding and spray drying.

Thereafter 0. 3 parts by weight of highly disperse silica are added to the pre-concentrate thus obtained and a 75 % strength wettable powder is obtained.

The total floatability of the wettable powder is 83 % and is 8Ο. 3 % after 3 months storage at 50°C.

Example 9 95.Ο parts by weight of ½ . 5 " " » " kieselgur · 0.5 " " " " sodium naphthalenesulphonate are ground wet as described under Example 1 and are subjected to spray drying at 70 - 78°C. On mixing the pre-concentrate thus obtained with formulation additives a wettable powder of the followin composition is obtained: Fw 5¾25 78.8 parts by weight of the above pre-concentrate ( 95 % strength) .0 » " »» " kieselgur 1.2 " » ·» " partially saponified polyvinyl ace .0 " " " " dried sulphite cellulose waste lye The total floatabillty of this 75 % strength wettabl powder is 80 %.

The degradation of active substance to free dinitro-sec. -butyl-phenol after 3 months' storage at 50°C is only 0.1 %.

The stabilising effect resulting from the use of a high-strength concentrate according to the invention is apparent from the following.

If a 50 strength Binapacryl wettable powder which has been manufactured in the conventional dry manner by very fine grinding on high performance mills, and which cannot be manufactured at a higher concentration in this manner, is compared with a wettable powder, again of 50 % strength, formulated from the Binapacryl pre-concentrate according to the invention by grinding on a simple cross beater mill and in other respects containing the same formulation constituents, then 2*5 % of free dinitro-sec.-butylpenol are present in the -conventional wettable powder af er 3 months storage at 50°C, whilst the wettable powder made from the pre-concentrate acoording to the invention only contains 0.3 - Λ %.

Since phytotoxic damage to the treated plants occurs at contents of free dinitro-sec.-butylphenol of more than 0*6 %, the active substance can, in the present case, only be employed - without the use of an additional stabiliser -through the pre-concentrate according to the invention*

Claims (1)

1. WHAT CLAIMED 13 As a ter a powder comprising about and above of a pesticide active ance conjunction with about 5 of optionally a carrier for the in a particle size o Process fo the manufacture of storable lettable or wettable powders of pesticides characterised that a suspension of pesticide active substance the presence o a substance as as optionally additionally carrier and further formulation is ground to a particle size of in a grinding and that the ground material subjected to a spray preferably by means of ce under a dry gas at 60 and usin an air pressure of 2 6 atmospheres gauge preferably 5 atmospheres g pressure or by centrifugal by means o a vaned and that subsequently about 3 of a highly disperse carrier as well as further formulation additives for highly lettable powders are optionally to the dry material thus A process as Claim 2 wherein the suspension of the active substance s an aq suspension and the dry gas temperature in the spray drying is 60 120 A according to 1 in which the active ingredient an herbicide or 5 A lettable powder according to Claim in which the pesticidal active ingredient is nitrobenzene 6 A wettable powder according to Claim 1 in which the pesticidal active ingredient is 7 A wettable powder according to Claim in which the pesticidal active ingredient is 8 A wettable powder according to Claim in which the pesticidal active ingredient is 9 A wettable powder according to Claim in which the pesticidal active ingredient is 10 A wettable powder according to Claim in which the pesticidal active ingredient is 11 A wettable powder according to Claim in which the pesticidal active ingredient is 12 A wettable powder obtained according to the process of Claim 13 A wettable powder obtained from a as defined in Claim Fw A wettable powder obtained according to the process of Claim 15 according to 1 The according to the processes any the Examples COHEN ZEDE ά Box Attorneys insufficientOCRQuality