WO2009030587A2

WO2009030587A2 - Silica dispersion

Info

Publication number: WO2009030587A2
Application number: PCT/EP2008/060663
Authority: WO
Inventors: Jochen Scheffler; Dirk Schäffner; Gabriele Perlet; Wolfgang Lortz
Original assignee: Evonik Degussa Gmbh
Priority date: 2007-09-06
Filing date: 2008-08-14
Publication date: 2009-03-12
Also published as: WO2009030587A3; DE102007042416A1

Abstract

Dispersion containing, in addition to water, 0.5 to 20% by weight of hydrophobic silica, 0.01 to 10% by weight of a gelling additive, or viscosity-increasing additive, 0.1 to 1% by weight of a preservative, 0 to 1% by weight of a surface -active substance, which, as further component, contains organic insecticides. It is produced by dispersing the individual components successively or together into the water and in this process deaerating the individual components before and/or during the addition or deaerating the dispersion during the individual dispersion steps. The dispersion can be used as insecticide.

Description

200700345 ^l

Silica dispersion

The invention relates to a silica dispersion, a process for production thereof and also use thereof.

Pulverulent hydrophobic silica is used for controlling sucking insects, wherein the application proceeds by means of dusting (DE 3 835 592) .

Disadvantageously, dust development is such that this method of insect control finds little acceptance.

The aqueous dispersions which are likewise described in DE 3835592, which consist of a hydrophobic silica and water, do not exhibit sufficient stability.

US 5830512 describes a dispersion in which sufficient stability is achieved by adding hydrophilic substances, such as, for example, silicas. However, by this means the active hydrophobic component is diluted by a hydrophilic substance. In addition, only a very low stability of the dispersion from hours to a few days is achieved.

EP 1 250 048 discloses stabilizing the dispersion of hydrophobic silica by gelling additives, such as xanthan gum, sodium alginates or neutralized carboxy- vinyl polymers, wherein mixtures of these additives are also possible.

These gelling additives, in combination with the hydrophobic Siθ2 particles and the air incorporated effect a marked structural viscosity.

A pronounced structural viscosity is also exhibited in the case of application by spraying: during the spraying process, the viscosity of the dispersion at the shear forces which occur is relatively low. After 200700345

- 2 - the dispersion drops impact the surface to be coated, the viscosity increases again greatly, in order to avoid dripping/running off from, in particular, vertical surfaces.

According to EP 1 250 048, in the production of the dispersion, in addition to the hydrophobic Siθ2 particles to be dispersed, large amounts of air are incorporated. Using the known dispersion processes, this cannot be avoided without the use of wetting surfactants and defoamers. For instance, in Example 1, a density of only 0.6 g/ml is stated, that is to say that 40% of the volume comprises air.

In order to achieve sufficient activity, a minimum mass must be applied to the surfaces to be sprayed. If, per spraying operation, only approximately 60% of the volume of the spraying appliances can be utilized, this means a significant reduction in efficacy.

Disadvantageously, the transport, packaging and disposal costs of the required packaging are higher by this fraction .

Also, during storage, a storage space approximately 40% larger must be taken into account.

In addition, using an air-containing dispersion, it is not possible to achieve a homogeneous, bubble-free coating of surfaces which are to be treated.

DE 10 2004 021 532 discloses a dispersion which, in addition to water, contains 0.5 to 20% by weight hydrophobic silica, 0.01 to 10% by weight of a gelling additive, or viscosity-increasing additive, 0.1 to 1% by weight of a preservative, 0 to 1% by weight of a surface-active substance. 200700345

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This dispersion can be used as insecticide against mites and other insects.

The known dispersion has the disadvantage that it loses activity at high atmospheric humidity, because the mites are not then dried out (see Figure 1) .

The object was therefore to modify the silica dispersion such that activity of the dispersion is provided even at high atmospheric humidity.

This object is achieved by the subject matter of the invention .

The invention relates to a dispersion containing, in addition to water, 0.5 to 20% by weight of hydrophobic silica, 0.01 to 10% by weight of a gelling additive, or viscosity-increasing additive, 0.1 to 1% by weight of a preservative, 0 to 1% by weight of a surface-active substance, which is characterized in that, as further component, it contains organic insecticides.

As organic insecticides, use can be made of the following active compound groups:

- natural active plant compounds which can be obtained by extraction, such as pyrethrum (from specific chrysanthemum species) , quassin (from the quassia wood of Quassia amara) , rotenone (from Derris elliptica) , azadirachtin (isolated from the seeds of the neem tree Azadirachta indica) , nicotine (from tobacco) and cinnamaldehyde (from Cinnamomum cassia)

- pyrethroids, such as cyfluthrin

- carbamates, such as triazamate or propoxur 200700345

- A -

- organic esters of phosphoric acid, such as parathion ("E 605"), dimethoate or phoxim (e.g. Byemite)

The organic insecticides, in a preferred embodiment, can be natural substances which are obtained by extraction from plants/plant parts.

In a particular embodiment, as insecticidal natural substance, use is made of "quassin", an extract from quassia wood.

"Quassin" is obtained as extract from the neotropical tree or shrub quassia amera. The bitter substances present in the extract quassin, neoquassin, picrasmin and isoquassin are the insecticidal components of quassia wood. (M. Holeschke et al . , Mitt. Dtsch. Ges. All. Angew. Ent 15 (Giessen 2006) pages 269-272) .

The fraction of water can be 68 to 99.4% by weight.

The specific density of the dispersion can be greater than 0.6 g/ml, preferably 0.7 to 1.02 g/ml .

As hydrophobic silica, use can be made of a pyrogenically produced, hydrophobicized silica. It can have a BET surface area of 20 to 600 m²/g.

The gelling additive or viscosity-increasing additive can be a biopolymer, such as, for example, xanthan gum, sodium alginate, carob bean meal, pectin, agar, carrageenans, alginates and/or neutralized carboxyvinyl polymers, or mixtures of these substances.

As preservatives, use can be made of preservatives which are approved for foods. These can be: sorbic acid, sodium sorbate, potassium sorbate, calcium sorbate, benzoic acid, sodium benzoate, potassium 200700345

- 5 - benzoate, calcium benzoate, PHB ethyl ester, PHB ethyl ester sodium salt, PHB propyl ester, PHB propyl ester sodium salt, PHB methyl ester, PHB methyl ester sodium salt, sulphur dioxide, sodium sulphite, sodium hydrogensulphite, sodium disulphite, potassium disulphite, calcium disulphite, calcium hydrogen- sulphite, biphenyl, orthophenylphenol, sodium ortho- phenylphenolate, thiabendazole, nisin, natamycin, formic acid, sodium formate, calcium formate, hexa- methylenetetramine, dimethyl dicarbonate, propionic acid, sodium propionate, calcium propionate, potassium propionate .

In addition the following are approved: nitrates, nitrites, carbon dioxide, chlorine and chlorine dioxide.

As surface-active substances, use can be made of ionic, nonionic and anionic surfactants.

The invention further relates to a process for producing the dispersion according to the invention which is characterized in that the individual components are dispersed successively or together into the water, and in which case the individual components are deaerated before and/or during the addition, or the dispersion is deaerated during the individual dispersion steps. Residual dispersed air still present can finally be removed by further mixing under vacuum.

In one embodiment of the invention, the deaeration can be carried out by means of application of vacuum.

Surprisingly, according to the invention, a stable and active dispersion can be achieved which does not contain extensive amounts of air. This deaerated dispersion can be achieved by the dispersion of previously deaerated hydrophobic Siθ2. Although 200700345

- 6 - subsequent deaeration of the dispersions is technically possible, it can only be achieved with great effort owing to the increased viscosity of the homogeneous phase water (gelling agent as additive) . At least a part as large as possible of the air which can be dispersed can be removed by deaeration measures before or during the dispersion.

In principle, any dispersion process is suitable that either makes possible prior deaeration of the powder to be dispersed or prevents air being dispersed during the dispersion .

One embodiment of the deaeration and dispersion is the utilization of a vacuum dissolver. In this case water and the gelling additive can be briefly predispersed, then the entire amount of hydrophobic SiC>2 added without stirring to the surface of the solution, the mixture evacuated and only then dispersion of the hydrophobic SiC>2 started.

A PSI Mix^® from NETZSCH can also achieve this deaeration of the powder.

In order to remove residual microbubbles, use can be made of deaeration units such as the DA-VS NETZSCH vacuum deaerator from NETZSCH, a vacuum-thin-film rotary process.

Use can be made of the dispersion according to the invention as insecticides, for example against

house dust mite: Dermatophagoides pteronyssinus red poultry mite: Dermanyssus gallinae red flour beetle: Tribolium castaneum granary weevil: Sitophilus granarius

Indian meal moth: Plodia interpunctella greenbug: Schiazaphis graminum. 200700345

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Examples

In all examples use was made of a DISPERMATπ® laboratory dissolver from VMA-GETZMANN GMBH having the CDS vacuum system. The CDS dispersion system permits dispersion processes to be carried out in vessels in a completely closed system under vacuum. A toothed disc of 70 mm diameter was used.

Production of INDISPRON D 110 TEC

To 475.5 g of deionized water are added I g of lecithin, 0.5 g of sorbic acid, 0.5 g of potassium sorbate and 7.5 g of Satiaxane xanthan gum and the mixture is dispersed for 15 minutes at 1000 rpm under vacuum on the dissolver. Then, 15 g of Aerosil R 812 S are charged and the mixture is deaerated for 10 minutes under vacuum without stirring. Finally, the Aerosil R 812 S is dispersed at 2000 rpm under vacuum.

Production of INDISPRON D 110 containing 5 mg of quassin/litre

A quassin-containing solution is obtained by aqueous extraction from quassia wood. Strictly speaking, "quassin" is an isomeric mixture of (+) quassin, isoquassin, neoquassin and if appropriate other quassinoids .

This extract from quassia wood is used in the examples. It is available commercially in standardized form.

To 467.3 g of deionized water are added I g of lecithin, 0.5 g of sorbic acid, 0.5 g of potassium sorbate and 7.5 g of Satiaxane xanthan gum and the mixture is dispersed for 15 minutes at 1000 rpm under vacuum on the dissolver. Subsequently, 8.3 g of quassin 200700345

- 8 - solution (300 mg of "quassin"/litre) are added and the mixture is mixed for 1 minute at 1000 rpm. Then, 15 g of Aerosil R 812 S are charged and the mixture is deaerated for 10 minutes under vacuum without stirring. Finally, the Aerosil R 812 S is dispersed at 2000 rpm under vacuum.

Production of INDISPRON 110 containing 20 mg of quassin/litre

To 442.5 g of deionized water are added I g of lecithin, 0.5 g of sorbic acid, 0.5 g of potassium sorbate and 7.5 g of Satiaxane xanthan gum and the mixture is dispersed for 15 minutes at 1000 rpm under vacuum on the dissolver. Subsequently, 133 g of quassin solution (300 mg of "quassin"/ϋtre) are added and the mixture is mixed for 1 minute at 1000 rpm. Then, 15 g of Aerosil R 812 S is charged and the mixture is deaerated for 10 minutes under vacuum without stirring. Finally, the Aerosil R 812 S is dispersed at 2000 rpm under vacuum.

Production of INDISPRON 110 containing 80 mg of quassin/litre

To 342.5 g of deionized water are added I g of lecithin, 0.5 g of sorbic acid, 0.5 g of potassium sorbate and 7.5 g of Satiaxane xanthan gum and the mixture is dispersed for 15 minutes at 1000 rpm under vacuum on the dissolver. Subsequently, 133 g of quassin solution (300 mg of "quassin'Vlitre) are added and the mixture is mixed for 1 minute at 1000 rpm. Then, 15 g of Aerosil R 812 S is charged and the mixture is deaerated for 10 minutes under vacuum without stirring. Finally, the Aerosil R 812 S is dispersed at 2000 rpm under vacuum.

Production of the comparative sample without Aerosil 200700345

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R 312 S, but containing 80 mg of quassin/litre

To 358.5 g of deionized water are added 0.5 g of sorbic acid, 0.5 g of potassium sorbate and 7.5 g of Satiaxane xanthan gum and the mixture is dispersed for 15 minutes at 1000 rpm under vacuum on the dissolver. Subsequently, 133 g of quassin solution (300 mg of "quassin"/litre) are added and the mixture is mixed for 1 minute at 1000 rpm.

The determination of the mortality of fully grown mites fed by sucking (in each case approximately 100 mites are placed on a dried active compound coating (wet film thickness 200 μm) on a galvanized steel plate in a plastic Petri dish which, after it has been closed, is stored with a fine fabric/gauze in a climatically controlled chamber and, after 24 h, the living, damaged or dead mites are counted) very readily proves the synergistic action of INDISPRON with other biocides, for example quassin:

Test organism: Dermanyssus gallinae Stage/state : adults, fed by sucking Temperature : 20-23⁰C Support material metal plates, galvanized steel Product amount - Layer thickness: 200 μm

200700345

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Both a pure quassin formula and also our INDISPRON D 110, at a very high relative humidity, show no activity at all on the mites. Only the combination exhibits a high mortality even at high relative humidities, as can occur in tropical regions or even in poorly ventilated animal houses and rainy weather even in Europe (see Figure 2) .

Even under "standard" relative humidities (50%, T, 20- 23°C), the synergistic action is already seen at the onset of activity: the combination acts more rapidly also under standard conditions (see Figure 3) .

200700345

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[see Figure 3;

Claims

200700345- 12 -Claims :

1. Dispersion containing, in addition to water, 0.5 to 20% by weight of hydrophobic silica, 0.01 to 10% by weight of a gelling additive, or viscosity- increasing additive, 0.1 to 1% by weight of a preservative, 0 to 1% by weight of a surface- active substance, characterized in that, as further component, it contains organic insecticides.

2. Dispersion according to Claim 1, characterized in that the organic insecticide is a natural substance obtained by extraction from plants/plant parts.

3. Dispersion according to Claim 2, characterized in that the organic insecticide is a natural substance which is obtained by extraction from quassia wood and which contains quassin and quassinoids.

4. Process for producing the dispersion according to Claim 1, characterized in that the individual components are dispersed successively or together into the water, in which case the individual components are deaerated before and/or during the addition, or the dispersion is deaerated during the individual dispersion steps and residual dispersed air which is still present is finally removed by further mixing under vacuum.

5. Process for controlling insects, characterized in that use is made of a dispersion according to Claim 1.