GB2149665A - Stabilized aqueous pesticidal suspension concentrate - Google Patents

Abstract

An aqueous pesticidal suspension concentrate comprises up to 50% by weight of a solid pesticide which is insoluble or only slightly soluble in water, 0.1 to 5% by weight of a non-ionic surfactant having an alkyl- or aralkyl-substituted aromatic ring as oleophilic group, 0.1 to 5% by weight of an alkylphenol polyglycol ether, a heteropolysaccharide thickener, and optionally other ingredients such as hydrophilic silica, propylene glycol and defoaming agent.

Description

SPECIFICATION Stabilized Aqueous Pesticidal Suspension Concentrate Technical Field The present invention relates to a stabilized aqueous pesticidal suspension concentrate. More particularly, the invention pertains to an aqueous pesticidal suspension concentrate which is capable of retaining uniform dispersibility for a long time and suited for not only usual-concentration ground application but also high-concentration applications such as aerial application [ULV application (ultra low volume application), LV application (low volume application) or S application (Spray application)1 and can be also used in admixture with other emulsifiable concentrates even for such high-concentration applications, owing to the blending of a specific surfactant and hetero-polysaccharide which is a water soluble thickner.

Description of the Prior Art Dusts, granules, wettable powders and emulsifiable concentrates are known as the typical preparation forms of agricultural chemicals. Among these preparation forms, dusts have the problem of much drifting to the environs at the time of application. Wettable powders are subject to heavy dusting at the time of preparation of a liquid spray because such wettable powders are composed of fine particles, and thus they pose the problem of injurious effects to the human body.Emulsifiable concentrates have the disadvantages that the types of the raw material pesticides which can be used as an emulsion are limited because such raw material pesticides are required to be easily dissoluble in organic solvents, that the preparations are unsafe and have a risk of causing a fire or other disasters during storage because of use of organic solvents, and that the application of such emulsifiable concentrates may cause damage to certain types of crops.

Recently, aerial application (ultra low volume application, low volume application or spray application) has become popular for saving time and labor in application works of agricultural chemicals. However, the conventional preparation forms of agricultural chemicals are not always suited for such aerial application and therefore the deveiopment of a new preparation form suited for aerial application has been desired. As a preparation suited for aerial application, there are known the suspension concentrates prepared by suspending the fine particles of water-insoluble or only slightly water-soluble technical grade pesticides in water or a hydrophilic solvent by adding an emulsifying agent and a dispersing agent.

These known suspension concentrates, however, are poor in long-term physical stability. Also, when they are used in admixture with other pesticidal emulsions for aerial application which is a type of high concentration application, there could take place flocculation of the suspended particles and the flocculates would be separated and sedimented to cause clogging of the strainer of the applicator adapted to a helicopter, etc. Further, such flocculates could induce phytotoxicity to the crops to which they adhere in the course of application of the mixed pesticidal preparation. Thus, these conventional preparations lacked the properties required of a suspension concentrate for aerial application.

Japanese Patent Laid-Open 129201/80, Japanese Patent Publication 24401/83 and Japanese Patent Laid-Open 124702/83 disclose the techniques relating to the suspension concentrates. However, the preparation disclosed in Japanese Patent Laid-Open 129201/80 has difficulties in achieving sufficient wetting and uniform suspension of the sparingly water soluble or water-insoluble active ingredient (technical grade pesticide) in water. Also, when such preparation is used in admixture with other known pesticidal emulsions, flocculates tend to be produced to cause clogging of the strainer in the applicator.

The suspension concentrate disclosed in Japanese Patent Publication 24401/83 is poor in long-term storage stability because of low yield value. The preparation disclosed in Japanese Patent Laid-Open 124702/83 can not be used in admixture with other technical grade pesticidal preparations. For controlling the insects which breed in the same season, it is commonly practiced to mix a pesticidal preparation with other preparation(s) on the spot and apply the mixed preparation for saving time and labor for such application. However, the conventional suspension concentrates, when used in admixture with other preparation(s), tend to form creamyflocculates which cause clogging of the strainer in the applicator.

Summary ofthe Invention An object of the present invention is to provide a stabilized aqueous pesticidal suspension concentrate.

The present invention was attained as a result of the assiduous studies by the present inventors for overcoming the said problems of the conventional aqueous pesticidal preparations. Thus, the present invention provides an aqueous pesticidal suspension concentrate using as active ingredient at least one pesticidal preparation which is solid at normal temperature and only sparingly soluble or insoluble in water and which can be uniformly and stably suspended in water, said pesticidal suspension concentrate being easy to treat, excellent in storage stability, suspensibility and dispersibility at the time of application, capable of aerial application and also usable in admixture with other technical grade pesticidal emulsions.

These prominent advantages of the preparation of this invention owe to the blending of a surfactant and heteropolysaccharide which is a water-soluble thickner.

Brief Description ofthe Invention An aqueous pesticidal suspension concentrate provided according to the present invention comprises essentially 50% by weight or less of at least one pesticide used as active ingredient which is solid at normal temperature and only sparingly soluble or insoluble in water, 0.1 to 5.0% by weight of an alkylphenol polyglycol ether used as surfactant,0.1 to 5.0% by weight of a non-ionic surfactant having an alkyl or aralkyl substituted aromatic ring as oleophilic group, and heteropolysaccharide, a water-soluble thickner, which is added in a sufficient amount so that the preparation will have a yield value of 10 dyme/cm2 or above at 25"C.

The present aqueous pesticidal suspension concentrate is also typified by the fact that it can be used in admixture with other emulsifiable pesticides.

A stabilized aqueous pesticidal suspension concentrate according to the present invention can be used not only for usual agricultural applications but also for wood preservative treatments in order to control brown-rot fungi, such as Coniophovaputeana, Serpula lacrymans, Tyromycespalustris or the like; white-rotfungi,such as Coriolus versicolor or the like; and soft-rot fungi, such as Chaetomium orthe like by treating the wood portions or the soil portions of the plants with the suspension concentrate. Furthermore, the suspension concentrate of the present invention can also be used for controlling phytotoxicities in lawns and grazing grounds caused by rust (Puccinia spp.), Rhizoctonia solani Kuhn and the like.

Detailed Description of Preferred Embodiments All types of known pesticidal preparations which are solid at normal temperature and only sparingly soluble or insoluble in water can be used as active ingredients for the composition of the present invention.

Examples of such pesticidal preparations include fungicides such as di-isopropyl 1,3-dithiolan-2ylidenemalonate (known by the general name of Isoprothiolane), 3'-isopropoxy-2-trifluorotoluanilide (known by the general name of Flutolanil), 3'-isopropoxy-2-toluanilide (known by the general name of Mepronil), and 4,5,6,7-tetrachlorophthalide (known by the general name of Phthalide); insecticides such as 2-t-tbutylimino-3-isopropyl-5-phenyl-3,4,5,6-tetrahydro-2H-1 ,3,5-thiadiazin-4-one (known by the general name of Buprofezin) and m-tolyl N-methylcarbamate (known by the general name of MTMC); and herbicides such as 2-chloro-4,6-bis(ethylamino)-1,3,S4riazine (known by the general name of CAT) and 2-chloro-4-ethylamino-6-isopropylamino-1 ,3,5-triazine (known by the general name- of Atrazine).The above-mentioned are merely exemplary and other similar pesticidal preparations can as well be used as active ingredients for the aqueous pesticidal suspension concentrate of the present invention.

These pesticidal preparations serving as active ingredients can be used either singly or in admixture in an amount of 50% by weight or less, preferably 10 to 50% by weight based on the total weight of the composition.

Atypical example of alkylphenol polyglycol ether used in this invention is nonylphenol polyglycol ether, and such ether is used in an amount of 0.1 to 50% by weight, preferably 0.1 to 3% by weight.

As to the non-ionic surfactant having an alkyl or aralkyl substituted aromatic ring as oleophilic group, there can be used one or more substances selected from formaldehyde condensates of alkylphenol polyglycol ethers and styrylphenol polyglycol ethers. These surfactants can be used either singly or in admixture. The amount of the non-ionic surfactant to be blended can be suitably selected from within the range of 0.1 to 5.0% by weight.

Heteropolysaccharide is used in this invention as a water soluble thickner. This polysaccharide, generally called Xanthan gum, is a high-molecular weight linear extracellular substance produced by the action of bacteria belonging to the genus Xanthomonas. This substance, for use in the present invention, should have a molecular weight exceeding 200,000, preferably over 1,000,000. It is used in such an amount that the produced pesticidal suspension concentrate will have a yield value of 10 dyne/cm2 or above at 250C, and usually the preferred amount range thereof is from 0.05 to 0.5% by weight.

Water is basically used as the solvent in the preparation of the aqueous pesticidal suspension concentrate according to the present invention. Water alone may be used, and if necessary it is possible to blend one or more organic solvents selected from the hydrophilic solvents such as methyl alcohol, ethyl alcohol, isopropyl alcohol, polyethylene glycol, ethylene glycol, propylene glycol, etc., and in some cases the hydrophobic solvents such as xylene, toluene, kerosene, mineral oils, vegetable oils, liquid paraffin, etc.

Such organic solvent(s), when used, is (are) blended in an amount of 1 to 30% by weight, preferably 10 to 20% by weight.

The aqueous pesticidal suspension concentrate of the present invention may contain where necessary other substances than the above-said ingredients, for example a defoaming agent such as a silicone-based defoaming agent mainiy composed of dimethyl polysiloxane in an amount not exceeding 5% by weight. It is also possible to blend hydrophilic silica or the like as a milling assistant for the technical grade material in an amount not greater than 5% by weight, as well as other substances required for the intended preparation. Other technical grade pesticides that can be used in admixture with the aqueous pesticidal suspension concentrate of the present invention include MEP emulsion, BPMC emulsion, MEP-BPMC emulsion, Diazinon emulsion, PAP emulsion, Isopropthiolane emulsion, Malathon emulsion, IBP emulsion and the like.

The aqueous pesticidal suspension concentrate according to the present invention can be prepared, for example, as follows. Predetermined amounts of an alkylphenol polyglycol ether, a non-ionic surfactant and if necessary a defoaming agent and an organic solvent (or solvents) are suspended or dissolved in water by a stirrer. Then the active ingredient is added thereto and the mixture is milled by a wet-milling equipment so that the particle size of the active ingredient will become um or less, preferably 0.5 to 3.0 cm. Then a predetermined amount of heteropolysaccharide is added to the mixture, followed by further mixing to obtain a homogeneous preparation.

The embodying examples of the present invention and some test examples are shown below. In the following descriptions of the examples, all "parts" are by weight unless otherwise noted.

EXAMPLE 1 Materials Used: Buprofezin 42.00 parts Nonylphenol polyglycol ether (10 EO) 1.40 parts Styrylphenol polyglycol ether (24 EO) 2.00 parts Propylene glycol 3.00 parts Defoaming agent 0.50 part Heteropolysaccharide 0.15 part Hydrophilic silica 3.00 parts Water 47.95 parts 1.40 Parts of nonylphenol polyglycol ether (10 EO), 2.00 parts of styrylphenol polyglycol ether (24 EO), 3.00 parts of propylene glycol and 0.50 part of defoaming agent (Silicone KM-73 produced by The Shin-Etsu Chemical Co., Ltd.) were added to 47.95 parts of water and they were dissolved and mixed for 20 minutes by an ordinary stirrer (Homomixer Model HV-M manufactured by Tokushukika Kogyo Co., Ltd.).Then 42.0 parts of Buprofezin and 3.00 parts of hydrophilic silica (Carplex #80 manufactured by Shionogi & Co., Ltd.) were added and the mixture was- milled for 3 hours by a wet-milling equipment (Attritor manufactured by Mitsui Miike Machinery Co., Ltd.). Finally, 0.15 part of heteropolysaccharide was added, followed by mixing for 20 minutes to obtain 100 parts of a homogeneous preparation.

In the same way, there were obtained the preparations of Examples 2-9, Referential Examples 1-10, Examples 1 Q12 and Referential Examples 11-15. The formulations for these preparations are shown in Tables 1,2 and 3.

TABLE 1

Example Example Example Example Example Example Example Example 2 3 4 5 6 7 8 9 Buprofezin 42.00 42.00 42.00 42.00 42.00 42.00 42.00 42.00 Nonylphenol polyglycol 1.40 1.40 1.40 1.40 1.40 1.40 1.40 1.40 ether (10 EO) Styrylphenol polyglycol - 1.00 0.80 0.80 0.80 0.80 0.80 0.80 ether (24 EO) Formaldehyde condensate 2.00 1.00 1.20 1.20 1.20 1.20 1.20 1.20 of nonylphenol polyglycol ether (30 EO) Propylene glycol 3.00 3.00 3.00 3.00 3.00 3.00 3.00 3.00 Dimethyl polysiloxane 0.50 0.50 0.50 0.50 0.50 0.50 0.50 0.50 (KM-73) Heteropolysaccharide 0.15 0.15 0.08 0.10 0.12 0.14 0.16 0.18 Hydrophilic silica 3.00 3.00 3.00 3.00 3.00 3.00 3.00 3.00 (Carplex) Water 47.95 47.95 48.02 48.00 47.98 47.96 47.94 47.92 Total 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 TABLE 2

Referential Example 2 3 4 5 6 7 8 9 10 Buprofezin 42.00 42.00 42.00 42.00 42.00 42.00 42.00 42.00 42.00 42.00 Nonylphenol polyglycol 1.40 1.40 1.40 1.40 1.40 1.40 1.40 1.40 1.40 1.40 ether (10 EO) Formaldehyde condensate of 2.00 - - - - - - - - naphthalenesulfonic acid Calcium lignosulfonate - 2.00 - - - - - - - Polyvinyl alcohol - - 2.00 - - - - - - Styrylphenol polyglycol - - - 0.80 0.80 0.80 0.80 0.80 0.80 0.80 ether (24 EO) Formaldehyde condensate of nonyl- - - - 1.20 1.20 1.20 1.20 1.20 1.20 1.20 phenol polyglycol ether (30 EO) Propylene glycol 3.00 3.00 3.00 3.00 3.00 3.00 3.00 3.00 3.00 3.00 Dimethyl polysiloxane (KM-73) 0.50 0.50 0.50 0.50 0.50 0.50 0.50 0.50 0.50 0.50 Heteropolysaccharide 0.15 0.15 0.15 - - - - - - Sodium alginate - - - - 0.12 0.18 - - - Carboxymethyl cellulose - - - - - - 0.12 0.18 - Hydroxypropylmethyl celulose - - - - - - - - 0.12 0.18 Hydrophilic silica (Carplex) 3.00 3.00 3.00 3.00 3.00 3.00 3.00 3.00 3.00 3.00 Water 47.95 47.95 47.95 48.10 47.98 47.82 47.98 47.92 47.98 47.92 Total 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 TABLE 3

Example Referential Examples 10 11 12 11 12 13 14 15 Flutolanil 24.30 24.30 24.30 24.30 24.30 24.30 24.30 24.30 Phthalide 18.60 18.60 18.60 18.60 18.60 18.60 18.60 18.60 Nonylphenol polyglycol 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 ether (10 EO) Styrilphenol polyglycol 1.00 1.00 1.00 - - 1.00 1.00 1.00 ether (24 EO) Formaldehyde condensate of 1.00 1.00 1.00 - - 1.00 1.00 1.00 nonyphenol polyglycol ether (30 EO) Formaldehyde condensate of - - - 2.00 - - - nathalenesulfonic acid Calcium lignosulfonate - - - - 2.00 - - Propylene glycol 3.00 3.00 3.00 3.00 3.00 3.00 3.00 3.00 Dimethyl polysiloxane (KM-73) 0.50 0.50 0.50 0.50 0.50 0.50 0.50 0.50 Hydrophilic silica (Carplex) 2.70 2.70 2.70 2.70 2.70 2.70 2.70 2.70 Heteropolysaccharide 0.10 0.13 0.15 0.15 0.15 - - Sodium alginate - - - - - - 0.15 0.25 Water 46.80 46.77 46.75 46.75 46.75 46.90 46.75 46.65 Total 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 Test Example 1 The viscosity (apparent viscosity and yield value) and physical stability (sediment volume ratio) of the preparations obtained in the respective Examples and Referential Examples were determined in the following ways.

Viscosity: Measured by using an E type viscometer (mfd. by Tokyo Keiki Ltd.), maintaining the specimen temperature at 25"C. Cone: 1'34". Apparent viscosity is the viscosity at a shear rate of 100 sec-1. Yield value was represented by shear stress at a shear rate of 0 sec-l.

Sediment Volume Ratio: 20 Ml of each preparation according to this invention or each comparative preparation is put into a graduated measuring cylinder with ground stopper having an inner diameter of 1.3 cm and a volume of 20 ml, and this cylinder is left stationary in a 40"C thermostatic chamber for one month. The volume V (ml) occupied by the sedimented particles is measured, and its ratio to the total volume is determined from the following equation. The obtained value was given as an index of the physical stability of the preparation.

V Sediment volume ratio= x100 20 The results are shown in Table 4.

TABLE 4

Aqueous Pesticidal Suspension Apparent Yield Sediment Concentrate Viscosity Value Volume Tested c.p.s. Dyne/cm2 Ratio Example 1 265 38 100 Example 2 265 40 100 Example 3 265 43 100 The Example 4 130 14 99 present Example 5 160 21 99 invention Example 6 210 28 100 Example 7 250 46 100 Example 8 280 58 100 Example 9 320 62 100 Example 10 192 13 89 Example 11 210 21 99 Example 12 185 30 100 Referential Example 4 92 0 66 5 248 0 85 6 6 432 0 85 7 7 260 0 78 Control " 8 216 0 75 9 9 50 0 73 10 55 0 73 13 20 0 60 14 14 230 0 60 15 280 0 60 Test Example 2 (Mixing Test) Water was put into a 500 ml wide-mouthed bottle and then a determined amount of a commercially sold pesticidal emulsion was putthereinto, followed by sufficient stirring to effect uniform emulsification and dispersion. Thereafter, a determined amount of each specimen of aqueous pesticidal suspension concentrate according to this invention was added and dispersed uniformly to form a mixed liquid pesticidal preparation diluted to a concentration suited for LV (low volume) application (8 litres per hectare).

Similar mixtures were prepared in the same way by using the control specimens (Referential Examples).

These mixed liquid preparations were left still for 2 hours and then passed through a 250-mesh strainer.

Whether the specimen tested can be used in admixture with a commercial emulsified pesticide or not was judged from the amount and state of the residue on the strainer. The results are shown in Table 5. In Table 5, o indicates that there was no residue on the strainer and the specimen can be used in admixture with a commercial liquid pesticide, and x indicates that there remained creamy residue on the strainer and the specimen can not be used in admixture with a commercial liquid pesticide.

TABLE 5

Fenitrothion/ Isopro Preparation Fenitrotion Osfencarb Osfencarb Diazinon Phenthoate thiolane Malathion IBP Tested No. Emulsion Emulsion Emulsion Emulsion Emulsion Emulsion Emulsion Emulsion Example 1 o o o o o o o o Example 2 o o o o o o o o Example 3 o o o o o o o o Example 11 o o o o o o o o Ref. x x x x x x x x Example 1 2 x x x x x x x x 3 x x x x x x x x 11 x x x x x x x x 12 x x x x x x x x

Claims (3)

1. A stabilized aqueous pesticidal suspension concentrate comprising 50% by weight or less of one or more pesticides which are solid at normal temperature and only sparingly soluble or insoluble in water, 0.1 to 5.0% by weight of an alkylphenol polyglycol ether, 0.1 to 5.0% by weight of a non-ionic surfactant having an alkyl or aralkyl substituted aromatic ring as oleophilic group, and heteropolysaccharide used as water soluble thickner in a sufficient amount so that the produced preparation will have a yield value of 10 dyne/cm2 or above at 25"C, said aqueous pesticidal suspension concentrate being usable in admixture with other emulsifiable pesticides.

2. A stabilized aqueous pesticidal suspension concentrate according to Claim 1, wherein said non-ionic surfactant having an alkyl or aralkyl substituted aromatic ring as oleophilic group is at least one member selected from the group consisting of formaldehyde condensates of alkylphenol polyglycol ethers and styrylphenol polyglycol ethers.

3. A stabilised aqueous pesticidal suspension concentrate, substantially as hereinbefore described with reference to Examples 1 to 12.