AU595590B2

AU595590B2 - Microencapsulated pyrethroid insecticidal and/or acaricidal composition for agricultural uses

Info

Publication number: AU595590B2
Application number: AU69991/87A
Authority: AU
Inventors: Kiyoshi Kasamatsu; Yukio Manabe; Toshiro Ohtsubo; Hisami Takeda; Kozo Tssji; Shigenori Tsuda
Original assignee: Sumitomo Chemical Co Ltd
Current assignee: Sumitomo Chemical Co Ltd
Priority date: 1986-03-17
Filing date: 1987-03-13
Publication date: 1990-04-05
Anticipated expiration: 2007-03-13
Also published as: DK170850B1; FR2595545A1; ES2004903A6; DE3708671C2; NO871027L; GB8706188D0; AU6999187A; NO173631B; SE8700907L; FR2595545B1; GB2187957B; IT8719720A0; NO173631C; DK134187A; DK134187D0; GB2187957A; SE8700907D0; DE3708671A1; IT1203368B; NO871027D0

Description

a orm COMMONWEALTH OF AUSTRALIA PATENTS ACT 1952-69 COMPLETE SPECIFICATION

(ORIGINAL)

S 7 Class <qW ;7 Int. Class Application Number: Lodged: Complete Specification Lodged: Accepted: Published: Priority e t f :Ieated Art: S t, Name of Applicant: *Aidress of Applicant A*tual Inventor: t c Address for Service: SUMITOMO CHEMICAL COMPANY, LIMITED 15, Kitahama 5-chome, Higashi-ku, Osaka, Japan TOSHIRO OHTSUBO, SHIGENORI TSUDA, YUKIO MANABE, HISAMI TAKEDA, KIYOSHI KASAMATSU and KOZO TSUJI EDWD. WATERS SONS, 50 QUEEN STREET, MELBOURNE, AUSTRALIA, 3000.

Complete Specification for the invention entitled: MICROENCAPSULATED PYRETHROID INSECTICIDAL AND/OR ACARICIDAL COMPOSITION FOR AGRICULTURAL USES The following statement is a full description of this invention, including the best method of performing it known to us i_ MICROENCAPSULATED PYRETHROID INSECTICIDAL AND/OR ACARICIDAL COMPOSITION FOR AGRICULTURAL USES The present invention relates to a microencapsulated pyrethroid insecticidal and/or acaricidal composition for agricultural uses which comprises at least one of pyrethroid compounds encapsulated in a wall formed of a synthetic polymer and having an average particle diameter of not more than 80 micrometers, wall thickness of not more than 0.3 micrometer, and average particle diameter/ wall thickness ratio of not less than 250, whereby an excellent residual effect is exhibited. The invention S also relates to a method for producing the same and a t 15 method of use thereof.

In general, pyrethroid inseccicides and/or j acaricides have high immediate insecticidal and/or acaricidal efficacies. They are prepared into formulations such as an emulsifiable concentrate, an oil, a wettable powder, a dust and the like and are now in use as agricultural insecticides and/or acaricides.

«As the residual efficacy of most pyrethroid insecticides and/or acaricides is low and the cost is .igh, it has S 25 been expected to find out a more economical method of use.

Generally, many of the pyrethroid insecti- VE tI cides and/or acaricides exhibit a relatively high fish toxicity, and when they are prepared into ordinary formulations such as an emulsifiable concentrate, an oil, a wettable powder and a dust, it may be difficult to lower the fish toxicity. Thus, there is a demand of the development of a formulation for reducing a fish toxicity.

55 C5 S::c S'an r~gc~a ar55*55" V T/ IX -2- When insecticides and/or acaricides are microencapsulated with a wall of a synthetic polymer, active ingredients are isolated irom the environment outside of the wall. So, they are protected from the decomposition by some factors such as microorganism, moisture and light. The release rate of the active ingredient through the wall is controlled when the active ingredient is encapsulated. For the above two reasons, microencapsulated insecticides and/or acaricides have, in most cases, a better residual efficacy. For instance, Japanese Patent Publication No. 55-38235 which relates to a pyrethroid insecticidal composition which is obtained by encapsulating a pyrethroid insecticide with a polyurethane resin, discloses that such microencapsulation results in a better residual effect.

As will be seen from the above, the microenc capsulation of insecticidesand/or acaricides will frequently tend to give a good residual efficacy.

c t However, even though the same insecticide or Sacaricide is encapsulated with the same wall material, it is not always expected to keep a given degree of the residual effect. In fact, it has been experienced that the degree of the residual efficacy differs among microcapsules.

SO The microencapsulation has the general tendency toward the lowering of fish toxicity of insecticides and/or acaricides, but the lowering rate has often been found to vary among microcapsules.

The present inventors made intensive studies and, as a result, found that various factors.concerned 3 with microcapsules, particularly a particle diameter and a wall thickness of the microcapsule, gave a great influence on the residual efficacy and the degree in reduction of fish toxicity. The present invention is accomplished on the basis of the above finding.

More particularly, the present inventors made intensive studies on conditions to give good residual efficacy in microencapsulation of pyrethroid insecticides and/or acaricides with synthetic polymers.

As a result, it is found the residual efficacy becomes especially high when pyrethroid insecticides and/or acaricides ar: microencapsulated with synthetic polymers in such a way that an average particle diameter of microcapsules is not more than 80 micrometers, wall thickness of the microcapsule is not more than 0.3 micrometer, and a ratio of average particle Sdiameter/wall thickness is not less than 250. In 0' addition, such microcapsules have lower fish toxicity.

For the microencapsulation, an interfacial polymerization method is convenient for its simplicity in which an oil-soluble reactant A is added to an oil 2 phase containing a pyrethroid insecticide and/or acaricide and is then dispersed in an aqueous phase, and then a reactant B capable of forming a polymer by reaction with the reactant A is added to the t' o aqueous phase, thereby forming a wall at the interface between both phases. Alternatively, the pyrethroid insecticide and/or acaricide-containing oil phase, to which the reactant A has been added, may be dispersed in an aqueous phase to which the reactant B has been previously added, followed by wall formation at the interface. Of course, when the wall is synthesized only by reaction of the reactant A in the oil phase and water, it is no need to add the reactant B. If necesj f I; i j- 4 sary, the oil phase may contain organic solvent which is almost immisible with water in addition to the reactant A and the pyrethroid insecticide and/or acaricide. In this case, the mixture of the reactant A, the pyrethroid insecticide and/or acaricide and the solvent is demanded to be uniform. The organic solvents used for this purpose among ordinary solvents include, for example, hydrocarbons such as xylene, toluene, alkylbenzenes, phenylxylylethane, hexane, heptane and the like, chlorinated hydrocarbons such as chloroform, ketones such as methyl ethyl ketone and cyclohexanone and the like, and esters such as diethyl phthalate and n-butyl acetate and the like.

The method of the microencapsulation using the interfacial polymerization is described.

1. Encapsulation of pyrethroid insecticides and/or acaricides with polyurethane resins: A solution containing at least one of pyrethroid insecticides and/or acaricides and a polyfunctional isocyanate compound having at least two isocyanate groups is dispersed in an aqueous solution containing a dispersing agent and polyhydric alcohol having at least two hydroxyl groups, followed by an interfacial polymerization.

e 5 A solution containing at least one of pyrethroid insecticides and/or acaricides and a polyfunctional isocyanate compound having at least two isocyanate groups is dispersed in an aqueous solution containing a dispersing agent, to which polyhydric alcohol having at least two hydroxyl groups is added, followed by an interfacial polymerization.

5 2. Encapsulation of pyrethroid insecticides and/or acaricides with polyurea resins: A solution containing at least one of pyrethroid insecticides and/or acaricides and a polyfunctional isocyanate compound having at least two isocyanate groups is dispersed in an aqueous solution containing a dispersing agent with or without polyfunctional amine having at least two amino groups, followed by an interfacial polymerization.

P00000 0 0000 0 00o *009 09 0 0000 a o o o0o 0 000 0 0 a 6 00 A solution containing at least one of pyrethroid insecticides and/or acaricides and a polyfunctional isocyanate compound having at least two 15 isocyanate groups is dispersed in an aqueous solution containing a dispersing agent, followed by an interfacial polymerization after addition of polyfunctional amine having at least two amino groups to the dispersed solusion.

3. Encapsulation of pyrethroid insecticides and/or acaricides with polyamide resins: A mixture of at least one of pyrethroid 25 insecticides and/or acaricides and polyfunctional acid chloride having at least two COC1 groups is dispersed in an aqueous solution containing a dispersing agent, and a polyfunctional amine having at least two amino groups is added to the dispersed solusion, followed by an interfacial polymerization.

4. Encapsulation of pyrethroid insecticides and/or acaricides with polyamide-polyurea resins: A mixture of a mixture of at least one of pyrethroid insecticides and/or acaricides and 00 00 9 0p cI It 4 I polyfunctional acid chloride having at least two COC1 groups and of polyfunctional isocyanate having at least two NCO groups is dispersed in an aaueous solution containing a dispersing agent, and polyfunctional amine having at least two amino groups is added to the dispersed solusion, followed by an interfacial polymerization.

Encapsulation of pyrethroid insecticides and/or acaricides with polyester resins: A mixture of at least one of pyrethroid insecticides and/or acaricides and polyfunctional acid chloride having at least two COC1 groups is dispersed in an aqueous solution containing a dispersing agent, and polyhydric alcohol having at least two hydroxyl groups is added to the dispersed solution, followed by an interfacial polymerization.

6. Encapsulation of pyrethroid insecticides and/or acaricides with polycarbonate resins: .A mixture of at least one of pyrethroid insecticides and/or acaricides and phosgene is dispersed in an aqueous solution containing a dispersing agent, and polyhydric alcohol having at least two hydroxyl groups is added to the dispersed solution, followed by an interfacial polymerization.

7. Encapsulation of pyrethroid insecticides and/or acaricides with polysulfonate resins: A mixture of at least one of pyrethroid insecticides and/or acaricides and polyfunctional sulfonyl chloride having at least two SO21C groups is dispersed in an aqueous solution containing a dispersing agent, polyhydric alcohol having at least two hydroxyl groups is added to the dispersed solution, followed by an interfacial polymerization.

8. Encapsulation of pyrethroid insecticides and/or acaricides with polysulfoneamide resins: j A mixture of at least one of pyrethroid insecticides and/or acaricides and polyfunctional sulfonyl chloride having at least two SO 2 C1 groups is dispersed in an aqueous solution containing a dispersing agent, and polyfunctional amine having at least two amino groups is added to the dispersed solution, followed by an interfacial polymerization.

9. Encapsulation of pyrethroid insecticides and/or acaricides with epoxy resins: A mixture of at least one of pyrethroid insecticides and/or acaricides and polyfunctional epoxy compound having at least two epoxy rings is t dispersed in an aqueous solution containing a dis- 'ct persing agent, and polyfunctional amine having at 4 least two amino groups is added to the dispersed solution, followed by an interfacial polymerization.

The suspension of microcapsules obtained after the encapsulation reaction may be used as it is Sor after dilution with water to a given concentration.

In practice, it is preferred that the suspension or its dilution is mixed with a thickening agent for use as a stable slurry-type formulation.

If an excess of amine is used for the polymerization, it may be neutralized, for example, with hydrochloric acid after the reaction.

8 The reaction period of time may vary depending on the type of the reactant and the reaction temperature and is preferably not shorter than hour.

When the solution containing at least one of pyrethroid insecticides and/or acaricides (hereinafter referred to simply as "oil phase") is dispersed in an aqueous solution containing a dispersing agent and the like (hereinafter referred to simply as "aqueous phase"), either a batchwise dispersing machine or a continuous feed-type dispersing machine may be used. The ratio of the oil phase to the aqueous phase at the time of the dispersion should preferably be at most 2 1. If the amount of the oil phase exceeds the above range, there is a great possibility that no oil-in-water type dispersion system required for the microencapsulation reaction is obtained, but a water-in-oil type dispersion system.

The conditions for obtaining microcapsules having an average particle diameter of not more than 80 micrometers, a wall thickness of not more than 0.3 fnicrometer and a value of average particle diameter/ wall thickness of not less than 250 are described, referring to encapsulation of pyrethroid insecticides and/or acaricides with polyurethane resins or polyurea resins. These conditions are fundamentally the same as for mic.oencapsulation with other types of S/ resins.

An amount of polyhydric alcohol necessary for microencapsulation with polyurethane resin is at least i

I

Ii Ii Ii ii 9 W .N M NCO NNCO OH x parts by weight MNCO NOH wherein W NCO: amount of a polyfunctional isocyanate compound to be charged into an oil phase (parts by weight);

NC

O number of isocyanate groups contained in one

NCO

molecule of polyfunctional isocyanate compound above;

MNC

O molecular weight of polyfunctional isocyanate compound above; MO molecular weight of polyhydric alcohol;

OH

NOH number of hydroxyl group in one molecule of the polyhydric alcohol.

An amount of polyfunctional amine necessary for microencapsulation with polyurea resin is at least W .N MNH NCO NCO MN2 2 Nx parts by weight MNCO NNH 2 wherein WNCO' NNCO and NCO same as above;

MNH

2 molecular weight of polyfunctional amine; N number of amino groups in one molecule of the

NH

2 polyfunctional amine.

In case where a polyfunctional isocyanate compound reacts with water to form a polyurea resin, all

V

H

I I

I

?rr cr- ~L~i7/^

-L

10 necessary is to use an enough water to have the oil phase dispersed therein.

The wall thickness of the microcapsule is proximately expressed by the following equation WW Pc d i0 W P 6 C W wherein W amount of a wall material (see Note); W amount of a core substance, parts by weight; which equals to W oi WC where W amount of the oil NCO oil oil phase to be charged at the time of the production of microcapsules;

WNC

O defined above; p density of the core substance; P density of the wall material; d average particle diameter of microcapsules.

Note: S(1) When a polyurethane wall is formed by reaction between a polyfunctional isocyanate compound and a polyhydric alcohol, S+ WNCO'NCO MOH W W W NCO M NOH

NCO

i -r 4: 1* 11 When a polyurea wall is formed by reaction between a polyfunctional isocyanate compound and a polyfunctional amine, S= WNCONNCO MNH2 W NCO MNCO N CONH2 When a polyurea wall is formed by reaction between a polyfunctional isocyanate compound and water, 2 moles of the isocyanate groups react with 1 mole of H 2 0 to produce 1 mole of the urea bond with 1 mole of CO 2 being evolved. Since the molecular weights of H 2 0 and CO 2 are 18 and 44, respectively, W N S=N CO NCO (18 44) W NCO M 2

NCO

Accordingly, the proximate equation can be reai written as follows.

When a polyurethane wall is formed by reaction between a polyfunctional isocyanate compound and a polyhydric alcohol, the following proximate equation (II) is obtained: ii I-n r SNCO OH PC d NCO(+ MNCONOH P W 6

MNC

0 ~i NO Wall thickness (T 1 W o oil

WN

NCO

When a polyurea wall is formed by reaction between a polyfunctional isocyanate compound I;-i I llsPLZ~ 12 and a polyfunctional amine, the following proximate equation (III) is obtained: N M p d WN NNCO M NH2 c d W (1 0 N C O MNCO'NNH2 PW 6 Wall thickness

(T

2 W W oil NCO When a polyurea wall is formed by reaction between a polyfunctional isocyanate compound and water, the following proximate equation (IV) is obtained: 13.NNCO Pc d w (1 P 6 NCO MNCO PW 6 Wall thickness (T 3 oil NCO The term "wall thickness" used herein means thickness which has been calculated according to the proximate equation (III) or (IV).

In order to produce microcapsules having an average particle diameter of not more than 80 micrometers, wall thickness of not more than 0.3 micrometer and a value of average particle diameter wall thickness of not less than 250, the production conditions should be determined as follows: d 80 micrometers,

T

1 0.3 micrometer and d/T 1 250 for the formation of a polyurethane wall by reaction between a polyfunctional isocyanate compound and a polyhydric alcohol; d 80 micrometers, T 2 0.3 micrometer and d/T 250 for the formation of a polyurea wall 2= -13by reaction between a polyfunctional isocyanate compound and a polyfunctional amine; and d micrometers, T 3 0.3 micrometer and d/T 3 250 for the formation of a polyurea wall by reaction between a polyfunctional isocyanate compound and water.

The average particle diameter of microcapsules is determined depending mainly on the type and concentration of a dispersing agent used for the dispersion and also on the degree of mechanical agitation during the dispersion. For the measurement of the average particle diameter, the Coulter counter Model TA-II, (available from Nikkaki) may be used, for example.

The polyfunctional isocyanates used for the microencapsulation include, for example, toluene diisocyanate, hexamethylene diisocyanate, adducts of toluene diisocyanate and trimethylolpropane, selfcondensates of hexamethylene diisocyanate, SUMIDUR L® (made by Sumitomo-Bayer Urethane Co., Ltd.), SUMIDUR I rt N® (made by Sumitomo-Bayer Urethane Co., Ltd.), and Stt J the like.

The polyhydric alcohols having at least two OH groups include, for example, ethylene glycol, propylene glycol, butylene glycol, hexanediol, heptanediol, dipropylene glycol, triethylene glycol, i glycerine, resorcinol, hydroquinone, and the like.

The polyfunctional amines having at least two NH 2 groups include, for example, ethylenediamine, hexamethylenediamine, phenylenediamine, toluenediamine, diethylenetriamine and the like.

SThe polyfunctional acid chlorides having !ii i 1 1 14 at least two COC1 groups include, for example, sebacoyl chloride, terephthaloyl chloride, trimesoyl trichloride and the like.

The polyfunctional sulfonyl chlorides having at least two SO 2 C1 groups are, for example, phenylenedisulfonyl chloride and the like.

The polyfunctional epoxy compounds having at least two epoxy rings are, for example, epichlorohydrin and the like.

The dispersing agent for dispersing an oil phase which comprises pyrethroid insecticides and/or acaricides and polyfunctional reactants include, for example, one or more of natural polysaccharides such as gum arabic, semi-synthetic polysaccharides such as carboxymethyl cellulose, methyl cellulose and the like, synthetic polymers such as polyvinyl alcohol, polyvinyl pyrrolidone and the like, fine mineral powders such as magnesium-aluminium-silicate, and the like. When the suspension dispersibility is weak, the suspension dispersibility may be improved by adding a known surfactant such as given in H. Horiguchi; "Synethetic 25 Surface Active Agent".

If necessary, natural polysaccharides such as xanthan guc, locust bean gum and the like, semisynthetic polysaccharides such as carboxymethyl cellulose, synthetic polymers such as sodium polyacrylate, fine mineral powders such as magnesium-aluminiumsilicate and the like may be used, singly or in combination, as a thickening agent.

Examples of the pyrethroid insecticides and/or acaricides include fenvalerate (alpha-cyano-3- 14 4.4P

I

phenoxybenzyl alpha-isopropyl-4'-chlorophenylacetate), fenpropathrin(alpha-cyano-3-phenoxybenzyl 2,2,3,3,tetramethylcyclopropanecarboxylate), permethrin [3phenoxybenzyl 2,2-dimethyl-3-(2,2,-dichlorovinyl)cyclopropane-l-carboxylate], cypermethrin[alphacyano-3-phenoxybenzyl 3-(2,2-dichlorovinyl) -2,2-dimethylcyclopropanecarboxylate], tetramethrin(3,4,5,6-tetrahydrophthalimidomethyl chrysanthemate), allethrin (3allyl- 2 -methylcyclopenta-2-ene-4-on-1-yl-cis,transcrysanthemate) phenothrin(3-phenyoxybenzyl cis, transchrysanthemate), deltamethrin[alpha-cyano-3-phenoxybenzyl 3-(2,2-dibromovinyl)- 2 ,2-dimethylcyclopropane carboxylate], cyhalothrin[alpha-cyano-3-phenoxybenzyl 2, 2 -dimethyl-3-(3,3,3-trifluoro-2-chloro-propenyl)cyclopropane carboxylate] and isomers thereof, and natural pyrethrin. However, these compounds should not be construed as limiting the insecticides and/or acaricides of the invention thereto but are mentioned only as examples. As a matter of course, mixtures of pyrethroid insecticides and/or acaricides and mixtures of pyrethroid insecticides and/or acaricides with other type of insecticides and/or acaricides may be used.

Ct The composition of the invention may contain not only microcapsules formed of the same and one wall material, but also microcapsules formed of the other wall materials. In addition, different active ingredients may be contained in different microcapsules.

If necessary, the composition of the invention may furw:ther contain a synergist such as piperonyl butoxide and a stabilizer ordinarily used for this purpose, e.g. BHT (2,6-di-t-butyl-4-methylphenol) or the like.

Insects or mites to be controlled according to the composition of the invention are those mentioned il r -1 i: i 16 below: insects of Hemiptera order such as whitebacked planthopper (Sogatella furcifera), smaller brown planthopper (Laodelphax striatellus), brown rice planthopper (Nilaparvata lugens), green rice leafhopper (Nephotettix cincticeps), green peach aphid (Myzus persicae), cotton aphid (Aphis gossypii), cabbage aphid (Brevicoryne brassicae), greenhouse whitefly (Trialeurodes vaporariorum) and sweet potato whitefly (Bemisia tabaci); insects of Lepidoptera order such as tea leafroller (Caloptilia thoivora), apple leafminer (Phyllonorycter ringoneella), citrus leafminer (Phyllocnistis citrella), diamond-back moth (Plutella xylostella), summer fruit tortrix (Adoxophyes orana), oriental tea tortrix (Homona magnanima), rice stem borer (Chilo supprossalis), oriental corn borer (Ostrinia funacalis), rice leafroller (Cnaphalocrocis medinalis), common cutworm (Spodoptera litura), armyworm (Pseudaletia separata), american bollworm (Heliothis armigera) and pink bollworm (Pectiophora gossypiella); insects of Coleoptera order such as cupreous chafer (Anomala cuprea), soybean beetle (Anomala rufocuprea), Japanese beetle (Popillia japonica), cucurbit leaf beetle (Aulacophora femolalis), striped flea beetle (Phyllotreta striolata), rice plant weevil (Echinocnemus squameus), maize weevil (Sitophilus S0 zeamais) and corn root worm (Diabrotica and mites (Acarina order) such as common spider mite (Tetranychus cinnabarinus), two-spotted spider mite cc tc (Tetranychus urticae), citrus red mite (Panonychus citri), European red mite (Panonychus ulmi), cryptomeria spider mite (Oligonychus bondoensis), bull tick (Boopilus microplus) and two-spined tick (Haemaphysalis longicornis) The present invention is described in more detail by way of examples. Comparative examples and 17 17 test examples are also described.

Example 1 Four grams of "SUMIDUR" L' (as indicated hereinbefore) and 100 of phenylxylylethane (commercial name: "HISOL" SAS 296 made by Nippon Petroleum Chemicals Co., Ltd.) were added to 100 g of fenvalerate and agitated until a uniform solution was obtained.

This solution was added to 400 g of an aqueous solution of 10wt% of polyvinyl alcohol (commercial name "GOSENOL" made by Nippon Gosei Kagaku K. and the dispersion was carried cut for several minutes by means of autohomomixer" (commercial name, Tokushukika Kogyo K. at room temperature until microdrops were formed. The number of revolutions was 1,250 r.p.m.

Thereafter, the dispersed solution was gently agitated at 60 0 C for 24 hours and a slurry of microencapsulated products was obtained.

Water was added to the slurry to make total weight of 1000 g, with the result that a slurry of o fenvalerate microcapsules with polyurethane wall having an active ingredient concentration of 10 wt% (Composition 1).

SThe resultant microcapsules had an average Sparticle diameter of 50 micrometers, wall thickness of S 30 0.109 micrometer, and average particle diameter/wall thickness ratio of 459.

Example 2 The procedure of Example 1 was repeated except that the number of revolutions of autohomomixer" (as used above) was 6,500 r.p.m. in place J 18of 1,250 thereby obtaining a slurry of fenvalerate microcapsules with polyurea wall having an active ingredient concentration of 10 wt% (Composition 2).

The resultant microcapsules had an average particle diameter of 5 micrometers, wall thickness of 0.011 micrometer and average particle diameter/ wall thickness ratio of 455.

Example 3 The procedure of Example 1 was repeated except that the amount of "SUMIDUR" L® (as indicated before) was changed to 0.8 g from 4 g and the number of revolutions of the autohomomixer" (as indicated before) was 6,500 r.p.m. in place of 1,250 r.p.m., thereby obtaining a slurry of fenvalerate microcapsules with polyurea wall having an active ingredient concentration of 10 wt% (Composition 3).

SThe resulting microcapsules had an average particle diameter of 5 micrometers, wall thickness of 0.002 micrometer and average particle diameter/wall thickness ratio of 2,500.

Example 4 The procedure of Example 1 was repeated except that the amount of "SUMIDUR" L (as indicated .t hereinbefore) was changed to 0.2 g from 4 g and the number of revolutions of autohomomixer" (as t

V

t indicated hereinbefore) was 2,300 r.p.m. in place of 1,250 thereby obtaining a slurry of fenvalerate microcapsules with polyurea wall having an active ingredient concentration of 10 wt% (Composition 4).

The resulting microcapsules had an average IL i 19 particle diameter of 20 micrometers, wall thickness of 0.011 micrometer and average particle diameter/wall thickness ratio of 10,000.

Example The procedure of Example 1 was repeated except that fenvalerate was replaced by fenpropathrin, and the number of revolutions of autohomomixer" (as indicated hereinbefore) was 6,500 r.p.m. in place of 1,250 thereby obtaining a slurry of fenpropathrin microcapsules with polyurea wall having an active ingredient concentration of 10 wt% (Composition The resulting microcapsules had an average particle diameter of 5 micrometers, wall thickness of 0.011 micrometer and average particle diameter/ wall thickness ratio of 455.

Example 6 g of "SUMIDUR" L (as indicated hereinbefore) was added to 200 g of fenvalerate and the mixture was heated under agitation until a uniform solution was obtained. The solution was added to 350 25 g of an aqueous solution containing 5 wt% of gum arabic as a dispersing agent and the dispersion was carried out for several minutes by means of "T.K.

autohomomixer" (as indicated hereinbefore) under heating. The number of revolutions was 8,500 r.p.m.

30 Thereafter, the dispersed solution was gently agitated at 80 0 C for 20 hours and a slurry of microencapsulated products was obtained.

Water was added to the obtained slurry to make a total weight of 1000 g, thereby obtaining.a slurry of fenvalerate microcapsules with polyurea wall having an active ingredient concentration of 20 wt% (Compo- C Ct ~Cl C 4'L 1 1 20 sition 6) The resulting microcapsules had an average particle diameter of 15 micrometers, wall thickness of 0.013 micrometer and average particle diameter/ wall thickness ratio of 1154.

Example 7 The procedure of Example 6 was repeated except that "SUMIDUR" L (as indicated hereinbefore) was used in an amount of 1 g in place of 1.5 g, 200 g of fenvalerate was replaced by 200 g of fenpropathrin, and the number of revolutions of autohomomixer" (as used hereinbefore) was 5,500 r.p.m. in place of 8,500 thereby obtaining a slurry of fenpropathrin microcapsules with polyurea wall having an active ingredient concentration of 20 wt% (Composition 7).

The thus obtained microcapsules had an average particle diameter of 50 micrometers, wall thickness of 0.03 micrometer, and average particle diameter/wall thickness ratio of 1,667.

Example 8 25 4 g of "SUMIDUR" L (as indicated hereinbefore) and 100 g of "HISOL" SAS-296 (as indicated hereinbefore) were added to 100 g of permethrin and the mixture was agitated until a uniform solution was obtained. The solution was added to 350 g of an 30 aqueous solution containing 5 wt% of gum. arabic as an dispersing agent and the dispersion was carried out for several minutes at room temperature by means of autohomomixer" (as used before). The number of revolutions was 8,000 r.p.m. Thereafter the dispersed solution was gently agitated at 55°C for 30 .hours and a slurry of microencapsulated products was obtained.

C t ;t tc it Ct rcce f ttt 'X-llla~-- ~P 21 Water was added to the obtained slurry to make a total weight of 1000 g and 1000 g of aqueous solution containing 0.3 wt% of xanthan gum and 0.6 wt% of magnesium-aluminium-silicate as a thickening agent was added, thereby obtaining a permethrin microcapsule slurry with polyurea wall having an active ingredient concentration of 5 wt% (Composition 8).

The resulting microcapsules had an average particle diameter of 20 micrometers, wall thickness of 0.044 micrometer and average particle diameter/ wall thickness ratio of 455.

Example 9 2 g of "SUMIDUR" L (as indicated hereinbefore) and 100 g of xylene were added to 100 g of cypermethrin and the mixture was agitated until a uniform solution was obtained. The solution was then added to 350 g of an aqueous solution containing wt% of gum arabic as a dispersing agent and the dispersion was carried out under heating for several minutes by means of autohomomixer" (as used hereinbefore). The number of revolutions was 5,500 25 r.p.m. Thereafter, 6 g of ethylenediamine was added into the dispersed solution. Thereafter, the dispersed solution was gently agitated at 700C for 24 hours and the slurry of microencapsulated products was obtained.

A IN hydrochloric acid aqueous solution was used to 30 adjust the pH of the slurry to 7, after which water was added until a total weight was 1000 g, thereby obtaining a slurry of cypermethrin microcapsules with polyurea wall having an active ingredient concentration of 10 wt% (Composition 9).

The thus obtained microcapsules had an i: ate.

rr r: i r r

C

Ctrr ce 1 22 average particle diameter of 50 micrometers, wall thickness of 0.065 micrometer and average particle diameter/wall thickness ratio of 769.

Example The procedure of Example 9 was repeated except that 2 g of "SUMIDUR" L (as indicated hereinbefore) was replaced by 2 g of "SUMIDUR" N (as indicated hereinbefore), 100 g of cypermethrin was replaced by 100 g of tetramethrin, 6 g of ethylenediamine was replaced by 6 g of phenylenediamine, and the number of revolutions was 8,000 thereby obtaining a slurry of tetramethrin microcapsules with polyurea wall having an active ingredient concentration of 10 wt% (Composition The thus obtained microcapsules had an average particle diameter of 20 micrometers, wall thickness of 0.027 micrometer, and average particle diameter/wall thickness ratio of 741.

t Example 11 1 g of "SUMIDUR" L (as indicated hereint before) and 50 g of xylene werp added to 150 g of 25 allethrin and the mixture was agitated until a uniform solution was obtained. The solution was then added to 350 g of an aqueous solution containing wt% of gum arabic as a dispersing agent and the dispersion was carried out at room temperature for 30 several minutes by means of autohomomixer" (as t used hereinbefore). The number of revolutions was 8,000 r.p.m. Thereafter the dispersed solution and gently agitated at 60 0 C for 24 hours and the slurry of of the microencapsulated products was obtained.

Water was added to the dispersion to make t c c e

E(

c i 4' -23a total weight of 1000 g, followed by dilution to 1:2 with an aqueous solution of 4 wt% of carboxymethyl cellulose ("CELLOGEN" 3H made by Daiichi Kogyo Seiyaku K. thereby obtaining a slurry of allethrin microcapsules with polyurea wall having an active ingredient concentration of 7.5 wt% (Composition 11).

The thus obtained microcapsules had an average particle diameter of 20 micrometers, wall thickness of 0.01 micrometer and average particle diameter/wall thickness ratio of 2000.

Example 12 The procedure of Example 6 was repeated 4 15 except that "SUMIDUR" L® (as indicated hereinbefore) used singly was replaced by a mixture of 0.8 g of "SUMIDUR" L (as indicated hereinbefore) and 0.1 g of toluene diisocyanate ('SUMIDUR" T80 made by Sumitomo Bayer Urethane Co., Ltd.), fenvalerate was replaced by phenothrin, and the number of revolutions 'of autohomomixer" (as used hereinbefore) was changed to 8,000 r.p.m. in place of 8,500 r.p.m., thereby obtaining a slurry of phenothrin microcapsules 0 with polyurea wall having an active ingredient y, 25 concentration of 20 wt% (Composition 12).

The thus obtained microcapsules had an average particle diameter of 20 micrometers, wall 7, thickness of 0.01 micrometer, and average particle diameter/wall thickness ratio of 2,000.

Example 13 1 g of "SUMIDUR" L (as indicated hereinbefore) and 160 g of fenitrothion [O,O-dimethyl-O- (3-methyl-4-nitrophenyl)phosphorothioate] were added to 40 g of fenvalerate and the mixture was agitated i 24 to obtain a uniform solution. The solution was added to 350 g of an aqueous solution containing 5 wt% of gum arabic and the dispersion was carried out for several minutes -at room temperature by means of autohomomixer" (as used before). The number of revolutions was 7,100 r.p.m. Thereafter the dispersed solution was gently agitated at 60 0 C for 24 hours and the slurry of the microencapsulated products was obtained.

Water was then added to the slurry to make a total weight of 1000 g, thereby obtaining a microcapsule slurry of 16 wt% of fenitrothion and 4 wt% of fenvalerate encapsulated with the polyurea resin (Composition 13).

The thus obtained microcapsules had an average particle diameter of 10 micrometers, wall thickness of 0.006 micrometer, and average particle diameter/wall thickness ratio of 1,667.

It Example 14 4.4 g of "SUMIDUR" L O (as indicated hereinbefore) and 100 g of phenylxylylethane (commercial S. 25 name: "HISOL" SAS-296 made by Nippon Petroleum Chem. Co., Ltd.) were added to 100 g of fenvalerate S and the mixture was agitated until a uniform solution was obtained. The solution was added to 400 g of an aqueous solution containing 10 wt% of polyvinyl 30 alcohol (commercial name: "GOSENOL" GL-05, mad by Nippon Gosei Kagaku Kogyo K. and the dispersion was carried out at room temperature for several minutes by means of autohomomixer" (Tokushu Kika Kogyo K. The number of revolutions was 1,250 r.p.m.

Six g of ethylene glycol was added into the dispersed solution. Thereafter the dispersed solution was gently 25 agitated at 60°C for 24 hours and the slurry of the microencapsulated products was obtained. Water was H added to the slurry to make a total weight of 1,000 g, thereby obtaining a slurry of fenvalerate microcapsules with polyurethane wall having an active ingredient concentration of 10 wt% (Composition 14).

The thus obtained microcapsules had an average particle diameter of 50 micrometers, wall thickness of 0.131 micrometer, and average particle diameter/wall thickness ratio of 382.

4 Example I The procedure of Example 14 was repeated except that autohomomixer" (as used before) was rotated at 2,300 r.p.m. in place of 1,250 r.p.m., thereby obtaining a fenvalerate microcapsule slurry with polyurethanewall having an active ingredient concentration of 10 wt% (Composition S'-t The thus obtained microcapsules had an average particle diameter of 20 micrometers, wall thickness of 0.052 micrometer, and average particle si 1 t diameter/wall thickness ratio of 385.

Example 16 !The procedure of Example 14 was repeated except that autohomomixer" (as used before) was r 0 rotated at 10,000 r.p.m. in place of 1,250 r.p.m., thereby obtaining a fenvalerate microcapsule slurry t t with polyurethane wall having an active ingredient concentration of 10 wt% (Composition 16).

The thus obtained microcapsules had an average particle diameter of 2 micrometers, wall thickness of 0.005 micrometer, and average particle diameter/ 26 wall thickness ratio of 400.

Example 17 The procedure of Example 14 was repeated except that an amount of "SUMIDUR" L (as indicated before) was changed to 0.9 g in place of 4.4 g and autohomomixer" (as indicated before) was rotated at 6,500 r.p.m. in place of 1,250 thereby obtaining a fenvalerate microcapsule slurry with polyurethane wall having an active ingredient concentration of 10 wt% (Composition 17).

The thus obtained microcapsules had an average particle diameter of 5 micrometers, wall thickness of 0.003 micrometer, and average particle diameter/wall thickness ratio of 1,667.

Example 18 2 er The procedure of Example 14 was repeated 1 20 except that an amount of "SUMIDUR" L (as indicated S before) was changed to 0.4 g in place of 4.4 g, thereby obtaining a fenvalerate microcapsule slurry with polyurethane wall having an active ingredient concentration of 10 wt% (Composition 18).

The thus obtained microcapsules had an Saverage particle diameter of 50 micrometers, wall thickness of 0.012 micrometer, and average particle diameter/wall thickness ratio of 4,167.

Example 19 .The procedure of Example 14 was repeated except that an amount of "SUMIDUR" L (as indicated before) was changed to 0.1 g in place of 4.4 g and autohomomixer" (as indicated before) was rotated at 1,500 r.p.m. in place of 1,250 thereby i p -'1 1 27 obtaining a fenvalerate microcapsule slurry with polyurethane wall having an active ingredient concentration of 10 wt% (Composition 19).

The thus obtained microcapsules had an average particle diameter of 30 micrometers, wall thickness of 0.002 micrometer, and average particle diameter/wall thickness ratio of 15,000.

Example The procedure of Example 14 was repeated except that fenvalerate was replaced by fenpropathrin, and autohomomixer" (as indicated before) was rotated at 6,500 r.p.m. in place of 1,250 r.p.m., thereby obtaining a fenpropathrin microcapsule slurry with polyurethane wall having an active ingredient concentration of 10 wt% (Composition The thus obtained microcapsules had an average particle diameter of 5 micrometers, wall thickness of 0.013 micrometer, and average particle diameter/wall thickness ratio of 385.

Example 21 1.5 g of "SUMIDUR" L (as indicated before) was added to 200 g of fenvalerate and the mixture was heated and agitated until a uniform solution was obtained. The solution was added to 350 g of an aqueous solution containing 5 wt% of gum arabic as dispersing agent and the dispersion was carried out. under heating for several minutes by the use of autohomomixer" (as indicated before). The number of revolutions was 6,000 r.p.m. Thereafter, 6 g of ethylene glycol was added into the dispersed solution. Thereafter the dispersed solution was gently agitated at 70 0 C for 20 .hours and the slurry of the microencapsulated products was obtaintri t I ti E 4- I tt 28 ed. Water was added to the dispersion to make a total weight of 1,000 g, thereby obtaining a fenvalerate microcapsule slurry with polyurethane wall having an active ingredient concentration of 20 wt% (Composition 21).

The thus obtained microcapsules had an average particle diameter of 40 micrometers, wall thickness of 0.039 micrometer, and average particle diameter/wall thickness ratio of 1,026.

Example 22 The procedure of Example 21 was repeated except that an amount of "SUMIDUR" L (as indicated before) was changed to 1 g in place of 1.5 g, 200 g of fenvalerate was replaced by 200 g of fenpropathrin, and autohomomixer" (as indicated before) was ro 1 ated at 6,800 r.p.m. in place of 6000 r.p.m., Sth-reby obtaining a fenpropathrin microcapsule slurry 20 with polyurethane wall having an active ingredient concentration of 20 wt% (Composition 22) t t C a The thus obtained microcapsules had an average particle diameter of 30 micrometers, wall 25 thickness of 0.02 micrometer, and average particle diameter/wall thickness ratio of 1,500.

Example 23 4 g of "SUMIDUR" L (as indicated before) and 150 g of "HISOL" SAS 296

R

were added to 100 g of S4 permethrin and the mixture was agitated until a uniform S...solution was obtained. The solution was added to 400 g of an aqueous solution containing 5 wt% of gum arabic as a dispersing agent and the dispersion was carried out at room temperature for several minutes by the use of autohomomixer" (as indicated before).

29 The number of revolutions was 8,600 r.p.m. Thereafter, 7 g of ethylene glycol was added into the dispersed solution. Thereafter the dispersed solution was gently agitated at 50 0 C for 36 hours and the slurry of the microencapsulated products was obtained. Water was added to the slurry to make a total weight of 1,000 g, followed by dilution to 1:2 with a aqueous solution containing 0.3 wt% of xanthan gum and 0.6 wt% of magnesium-aluminium-silicate as a thickening agent, thereby obtaining a permethrin microcapsule slurry I with polyurethane wall having an active ingredient concentration of 5 wt% (Composition 23).

The thus obtained microcapsules had an average particle diameter of 15 micrometers, wall thickness of 0.029 micrometer, and average particle diameter/wall thickness ratio of 517.

Example 24 2 g of "SUMIDUR" L (as indicated before) and 50 g of xylene were added to 100 g of cypermethrin t V and the mixture was agitated until a uniform solution was obtained. The solution was added to 350 g of an aqueous solution containing 5 wt% of gum arabic as a J c25 dispersing agent and the dispersion was carried out under heating for several minutes by the use of "T.K.

autohomomixer" (as indicated before). The number of revolutions was 5,000 r.p.m. Thereafter, 6 g of propylene glycol was added into the dispersed solution.

Thereafter the dispersed solution was gently agitated at 70°C for 24 hours and the slurry of the microencapsulated products was obtained. Water was added to the slurry to make a total weight of 1,000 g, thereby obtaining a cypermethrin microcapsule slurry with polyurethane wall having an active ingredient concentration of 10 wt% (Composition 24).

I

30 The thus obtained microcapsules had an average particle diameter of 60 micrometers, wall thickness of 0.101 micrometer, and average particle diameter/wall thickness ratio of 594.

Example The procedure of Example 14 was repeated except that an amount of "SUMIDUR" L® (as indicated before) was changed to 2 g in place of 4.4 g, 100 g of "HISOL" SAS 296 vwas replaced by 100 g of xylene, fenvalerate was replaced by tetramethrin, and "T.K.

autohomomixer" (as indicated before) was rotated at 2,300 r.p.m. in place of 1,250 thereby obtaining a tetramethrin microcapsule slurry with polyurethane wall having an active ingredient cocentration of wt% (Composition The thus obtained microcapsules had an average particle diameter of 20 micrometers, wall thickness of 0.022 micrometer, and average particle diameter/wall thickness ratio of 909.

Example 26 One g of "SUMIDUR" L (as indicated before) 25 and 50 g of xylene were added to 100 g of allethrin St and the mixture was agitated until a uniform solution was obtained. The solution was added to 260 g of an aqueous solution containing 5 wt% of gum arabic as a dispersing agent and the dispersion was carried out at room temperature for several minutes by the use of SC autohomomixer" (as indicated before). The number trc of revolutions was 8,000 r.p.m. Thereafter, 7 g of ethylene glycol was added into the dispersed solution.

Thereafter the dispersed solution was gently agitated at 60 0 C for 24 hours and the slurry of the microencapsulated products was obtained.

-31- Water was added to the slurry to make a total weight of 1,000 g, followed by dilution to 1:2 with an aqueous solution containing 4 wt% of carboxymethyl cellulose ("CELLOGEN" 3H® made by Daiichi Kogyo Seiyaku K. thereby obtaining an allethrin microcapsule slurry with polyurethane wall having an active ingredient concentration of 5 wt% (Composition 26).

The thus obtained microcapsules had an average particle diameter of 20 micrometers, wall thickness of 0.015 micrometer, and average particle diameter/wall thickness ratio of 1,333.

Example 27 The procedure of Example 21 was repeated except that "SUMIDUR" L (as used before) was replaced by a mixture of 0.8 g of "SUMIDUR" L and 0.1 g of toluene diisocyanate ("SUMIDUR" T80 made by Sumitomo- Bayer Urethane Co., Ltd.), and 200 g of fenvalerate was replaced by 200 g of phenothrin, thereby obtaining a phenothrin microcapsule slurry with polyurethane wall t having an active ingredient concentration of 20 wt% (Composition 27).

25 The thus obtained microcapsules had an SIt4 average particle diameter of 20 micrometers, wall thickness of 0.011 micrometer, and average particle Sdiameter/wall thickness ratio of 1,818.

Example 28 Zero point nine g of "SUMIDUR" L (as indicated before) and 160 g of fenitrothion [0,0dimethyl-O-(3-methyl-4-nitrophenyl)phosphorothioate] were added to 40 g of fenvalerate and the mixture was agitated until a uniform solution was obtained. The solution was added to 400 g of an aqueous solution

I

I i -32containing 10 wt% of "GOSENOL" GL-05 (as indicated before) and the dispersion was carried out at room temperature for several minutes by the use of "T.K.

autohomomixer" (as indicated before). The number of revolutions was 6,500 r.p.m. Thereafter, 10 g of I ethylene glycol was added into the dispersed solution.

Thereafter the dispersed solution was gently agitated at 60°C for 24 hours and the slurry of the microencapsulated products was obtained. Water was added to the slurry to make a total weight of 1,000 g, thereby obtaining a microcapsule slurry with polyurethane wall having 16 wt% of fenitrothion and 4 wt% of fenvalerate (Composition 28).

Example 29 STwo hundred g of fenvalerate, 50 g of xylene S* and 4 g of trimesoyl chloride were mixed until the solution was uniform. The solution was added to 500 g of an aqueous 2 gum arabic. The dispersion was 1 t 25 carried out at room temperature for several minutes by the use of autohomomixer" (Tokushu Kika Kogyo K. The dispersed solution was gently agitated Swith a magnetic stirrer, into which 100 g of an aqueous solution containing 3 g of diethylenetriamine and 6 g of sodium carbonate, followed by allowing it to stand C for 2 hours while continuing the gentle agitation.

C

Thereafter, the suspension was neutralized with an IN hydrochloric acid solution. Water was added thereto so as to make a total weight of 1,000 g, thereby obtaining a fenvalerate microcapsule slurry.with polyurethane wall having an active ingredient concentration of 20 wt% (Composition 29).

33 The thus obtained microcapsules had an average particle diameter of 22 micrometers, wall thickness of 0.049 micrometer, and average particle diameter/wall thickness ratio of 449.

Comparative Example 1 The procedure of Example 1 was repeated except that an amount of "SUMIDUR" L (as indicated before) was changed to 15 g in placed of 4 g and "T.K.

autohomomixer" (as indicated before) was rotated at 6,500 r.p.m. in place of 1,250 thereby obtaining a fenvalerate microcapsule slurry with polyurea wall having an active ingredient concentration of 10 wt% (Comparative Composition 1).

The thus obtained microcapsules had an average particle diameter of 5 micrometers, a wall thickness of 0.04 micrometer, and average particle diameter/wall thickness ratio of 125.

SComparative Example 2 StThe procedure of Example 5 was repeated except that an amount of "SUMIDUR" L' (as indicated before) was changed to 15 g from 4 g and autohomomixer" (as indicated before) was rotated at 2,150 r.p.m. in place of 1,500 thereby obtaining a t. fenpropathrin microcapsule slurry with polyurea wall Shaving an active ingredient concentration of 10 wt% (Comparative Composition 2).

e The thus obtained microcapsules had an average particle diameter of 25 micrometers, wall thickness of 0.333 micrometer, and average particle diameter/wall thickness ratio of 34 Comparative Example 3 A fenvalerate emulsifiable concentrate having an active ingredient concentration of 10 wt% was prepared by a usual manner using the following recipe (Comparative Composition 3).

Fenvalerate 10 parts by weight "SORPOL" 3005 X 10 parts by weight (registered trade name of Toho Kagaku K. K.: mixture of a nonionic surface active agent and an anionic surface active agent) Xylene balance 100 parts by weight Comparative Example 4 A fenpropathrin emulsifiable concentrate having an active ingredient concentration of 10 wt% was prepared by a usual manner using the following "t recipe (Comparative Composition 4).

Fenprospathrin 10 parts by weight 25 "SORPOL" 3005 X 10 parts by weight (as used above) Xylene balance F 100 parts by weight Comparative Example The procedure of Example 14 was repeated except that an amount of "SUMIDUR" L (as used before) was changed to 17.6 g from 4.4 g and autohomo- 35 mixer" (as used before) was rotated at 6,500 r.p.m.

in place of 1,250 thereby obtaining a fenvalerate microcapsule slurry with polyurethane wall having an active ingredient concentration of wt% (Comparative Composition The thus obtained microcapsules had an average particle diameter of 5 micrometers, wall thickness of 0.052 micrometer, and average particle diameter/wall thickness ratio of 96.

Comparative Example 6 The procedure of Example 20 was repeated except that an amount of "SUMIDUR" L® (as used before) was changed to 25 g from 4.4 g and "T.K.

autohomomixer" (as used before) was rotated at 2,300 r.p.m. in place of 6,500 thereby obtaining a fenpropathrin microcapsule slurry with polyurethane wall having an active ingredient concentration of 10 wt% (Comparative Composition 6).

The thus obtained microcapsules had an average particle diameter of 20 micrometers, wall thickness of 0.291 micrometer, and average particle diameter/wall thickness ratio of 69.

Test Example 1 A 1:1000 dilution with water of each test composition, indicated in Table 1, was sprayed by means of a spray gun over potted cabbages (ever harvesting Sf cabbages) mounted on a turn table in an amount 50 ml per five pots. Each dilution contained 0.0002 wt% of special Rino® (made by Nippon Noyaku K. as a spreader.

The thus treated cabbage pots were allowed 36 to stand in a glass greenhouse and leaves of the cabbages were cut away after a predetermined period of time, followed by a placing in a cup having a diameter of 12 cm together with 10 tobacco cut worm/larvae-f After 48 hours, the number of the dead insects was checked. The test was repeated three times and a mortality was calculated according to the following equation.

(total number of the dead of three tests) Mortality(%) (total number of tested insects in three tests) x 100 The results are shown in Tables 1 and 2.

tIt I 4 o t I -rr S non

J,

44 C 44 44 1444 Table 1 Efficacy on Tobacco Cutworms (Mortality Residual Averge allAverge artcle Mortality at the Test Avrge WllAe a eril indicated days after particle thickness dimtrtreatment compositions diameter Wall Thickness 0 7 days 14 days (Pim) (rm) P resent composition 1 50 0.109 459 100 83.3 70.0 2 5 0.011 455 83.3 66.7 53.3 3 5 0.002 2500 100 83.3 50.0 4 20 0.002 10000 100 90.0 73.3 Comparative composition 1 5 0.04 125 63.3 50.0 36.7 3 90.0 63.3 40.0 rr n o r r D o r cor n Table 2 Residual Efficacy on Tobacco Cutworms (Mortality AverAvera ge particle Mortality at the Test Wall indicated days after particle diameter treatment compositions diameter thickness 7 14 28 (Pm) (1m) Wall thickness 0 7 14 28 days days days Present composition 20 0.052 385 86.7 73.3 70.0 66.7 17 5 0.003 1667 100 83.3 70.0 43.3 18 50 0.012 4167 100 90.0 76.7 63.3 19 30 0.002 15000 100 86.7 73.3 66.7 Comparative composition 3 0.052 60 96.7 43.3 70.0 20.0 53.3 13.3 26.7 39 Test Example 2 Potted kidneys 2 weeks after seeding (two kidneys per pot) was inoculated with about 30 female carmine mites per pot. Three days after the inoculation, a 1:1000 dilution of each test composition in Table 3 was sprayed over the pots on a turn table by means of a spray gun in an amount of 50 ml per pots. Each dilution contained 0.0002 wt% of special Rino (as indicated above) as a spreader.

The treated pots were allowed to stand in a net-shaded chamber and the number of the female mites was checked after a predetermined period of time.

9 t 11 1 tl Table 3 Residual Efficacy on Carmine Mites (Total number of female mites in 5 pots) Aveag WllAverage particle Residual effect (total Avraesal diameter number) at the indicated Tetparticle tikesdays after treatment compositions diameter thcns (im) (vm) Wall thickness 0 1 7ay 21 0 day das days Present composition 5 0.011 455 162 36 17 Comparative composition 2 25 0.333 75 161 87 98 140 4 163 44 29 121 Non-16 22 23 treatment16 22 23 41 Test Example 3 The same procedure as in Test Example 2 was repeated using test compositions indicated in Table 4.

The test results are shown in Table 4.

c t Si e(r i i -jS N l nnn *Ih n C f Cih Ir I I on r Table 4 Residual Efficacy on Carmine Mites (Total number of female mites in 5 pots) Average Residual effect (total Test Ave e Average particle number) at the indicated particle diameter days after treatment compositions diameter thickness (Nm) Wall thickness 0 1 7 21 day days days Present composition 5 0.013 385 162 37 11 42 Comparative composition 6 20 0.291 69 161 80 87 135 4 163 43 20 119 Non- 161 226 232 752 treatment 1 43 Test example 4 Fenvalerate microcapsule slurries of the invention (Present Compositions 1 and 4) and a fenvalerate emulsifiable concentrate (Comparative Composition 3) were each diluted to a predetermined concentration and placed in a 21 cm x 16 cm x 23 cm glass container in an amount of 5 liters. Ten red killifishes were placed in the container in order to check the life or death after 48 hours. Based on the results, a concentration for a median lethal dose was determined as TLm 48

(MC).

The above procedure was repeated using fenvalerate stock to determine a median lethal dose for fenvalerate as TLm 48

(TG).

A value of TLm 48 (MC)/TLm 4 8 (TG) was calculated and taken as a fish toxicity reduction rate. The results are shown in Table 4 Table Fish Toxicity Reduction Rate For Red Killifish h.- Ot ct e t t I

C

Test compositions Fish Toxicity Reduction Rate Present composition 1 600 4 Comparative composition 3 1

Claims

1. A microencapsulated pyrethroid insecticidal and/or acaricidal composition for agricultural use prepared by an interfacial polymerisation method encapsulated in a micro- capsule formed of a synthetic polymer and having an average particle diameter of not more than 80 micrometers, wall thickness of not more than 0.3 micrometer, and average particle diameter/wall thickness tio of not less than 250.

2. The insecticidal and/or acaricidal composition according to Claim 1, wherein said synthetic polymer for the microcapsules is a member selected from the group consisting of polyurethane resins, polyurea resins, polyamide resins, polyamide-polyurea resins, polyester resins, polycarbonate resins, polysulfonate resins, polysulfonamide resins and epoxy resins.

3. The insecticidal and/or acaricidal composition according to Claim 2 wherein said synthetic polymer is a polyurea resin.

4. The insecticidal and/or acaricidal composition according to Claim 2, wherein said synthetic polymer is a polyurethane resin. The insecticidal and/or acaricidal composition *o o according to any one of Claims 1, 2, 3 and 4, wherein the pyrethroid compound is a member selected from the group consisting of fenvalerate, fenpropathrin, permethrin, cypermethrin, tetramethrin, allethrin, phenothrin, deltamethrin, cyhalothrin, their isomers, and mixtures thereof. A method for controlling insects and/or I i a j 45 mites by use of the microencapsulated composition of Claim 1. A process for preparing a microencapsulated pyrethroid insecticidal and/or acaricidal composition containing at least one of pyrethroid compounds encapsulated in a wall formed of a synthetic polymer and having an average particle diameter of not more than 80, micrometers, wall thickness of not more than 0.3 micrometer and average particles diameter/wall thickness ratio of not less than 250, which comprises adding an oil-soluble reactant A to an oil phase containing pyrethoid insecticide and/or acaricide, dispersing the mixture in water, adding, if necessary, a reactant B to the dispersed solution, said reactant B being of' able to react with the reactant A to form a polymer and allowing interfacial polymerization to proceed between the S' f reactant A and the reactant B above or in absence of I t reactant B interfacial polymerization to proceed with reactant A between the oil and water phases; or adding the reactant A to an oil phase containing pyrethroid insecticide and/or acaricide, dispersing the oil phase in an aqueous phase containing the reactant B, and allowing polymerization between the reactant A and the reactant B above to proceed. 06

8. A process according to Claim 7 wherein the material of the wall is selected from a group consisting of polyurethane resin, polyurea resin, polyamide resin, polyamide-polyurea copolymer, polyester resin, polycarbonate resin, polysulfonate resin, polysulfonamide resin and epoxy resin.

9. A process according to Claim 7 wherein the reactant A is selected from a group consisting of polyfunctional isocyanate having at least two isocyanate groups, polyfunctional acid chloride having at least IAS:EK(8:61) -46- two COC1 groups, phosgene, polyfunctional sulfonyl- chloride having at least two SO 2 Cl groups and poly- functional epoxy compound having at least two epoxy rings. A process according to Claim 7 wherein the reactant B is selected from a group consisting of polyhydric alcohol having at least two hydroxyl groups and polyfunctional amine having at least two amino groups.

11. A process according to Claim 7 wherein the insecticide and/or acaricide is selected from fenvalerate, fenpropathrin, permethrin, cypermethrin, tetramethrin, allethrin, phenothrin, deltamethrin, cyhalothrin, their isomers, and mixtures thereof. i t t It t 'DATED this 12th day of March 1987. 1 8 6 SUMITOMO CHEMICAL COMPANY, LIMITED 014D eo a S.i EDWD. WATERS SONS t PATENT ATTORNEYS QUEEN STREET L MELBOURNE. VIC. 3000. *8 I I I fh 4