SCHAEFFNER DIRK (DE)
PERLET GABRIELE (DE)
LORTZ WOLFGANG (DE)
SCHEFFLER JOCHEN (DE)
SCHAEFFNER DIRK (DE)
PERLET GABRIELE (DE)
LORTZ WOLFGANG (DE)
| WO2005104851A2 | 2005-11-10 | |||
| WO2004104154A2 | 2004-12-02 |
| Patent claims
1. Dispersion comprising hydrophobic pyrogenically prepared silicon dioxide, alcohol and at least one additive which promotes the dispersion.
2. Dispersion according to Claim 1, characterized in that it comprises a rheology-promoting agent.
3. Dispersion according to Claim 2, characterized in that hydroxypropylcellulose is used as rheology- promoting agent.
4. Use of the dispersion according to Claim 1 as acaricide and insecticide.
5. Spray can comprising the dispersion according to Claim 1.
6. Spray can according to Claim 5, additionally comprising a propellent.
7. Spray can according to Claim 6, characterized in that propellents, such as propane, butane or a mixture of propane and butane, are used with a proportion of propellent gas of 10-80%.
8. Spray can according to Claim 6, characterized in that nitrogen is used as propellent gas.
9. Spray can according to Claim 6, characterized in that nitrous oxide is used as propellent gas.
10. Spray can according to Claim 5, characterized in that the pressure necessary for the spraying is produced by a pump system. |
Silicon dioxide dispersion
The invention relates to a silicon dioxide dispersion, to a process for the preparation thereof and to the use thereof.
Pulverulent hydrophobic silica is used to combat sucking insects, the application taking place by means of dusting (DE 38 35 592) .
Disadvantageously, dust development is such that this method of insect control finds little acceptance.
The aqueous dispersions likewise described in DE 38 35 592, which consist of a hydrophobic silica and water, do not exhibit satisfactory stability.
US 5 830 512 describes a dispersion in which satisfactory stability is achieved by addition of hydrophilic substances, such as, for example, silicas. However, the active hydrophobic component is through this diluted by a hydrophilic substance. Furthermore, only a very low stability of the dispersion, from hours to a few days, is achieved.
EP 1 250 048 describes stabilizing the dispersion of hydrophobic silicon dioxide through gelling additives, such as, for example, xanthan gum, sodium alginates or neutralized carboxyvinyl polymers, mixtures of these additives also being possible.
These gelling additives bring about, by interaction with the hydrophobic SiO 2 particles and the incorporated air, a marked structural viscosity which is exhibited when applying by spraying. Thus, during the spraying process, the viscosity of the dispersion is relatively low at the shear forces acting on it. After the dispersion drops impact the surface to be coated, the visocity again increases strongly, in order to avoid dripping/running off from in particular vertical surfaces.
According to EP 1 250 048, in addition to the hydrophobic Siθ2 particles to be dispersed, large amounts of air are incorporated. With the known dispersion processes, this cannot be avoided without the use of wetting surfactants and antifoaming agents. Thus, in Example 1, a density of only 0.6 g/ml is specified, which means that approximately 40% of the volume consists of air.
In order to achieve a satisfactory activity, a minimum weight has to be applied to the surfaces to be sprayed. If, per spraying operation, only approximately 60% of the volume of the spraying appliances can be used, this represents a significant reduction in the effectiveness.
Disadvantageously, the transportation, packaging and waste disposal costs of the required packaging are higher by this proportion.
In addition, during storage, an approximately 40% larger storage space has to be taken into account.
Furthermore, with an air-comprising dispersion, it is not possible to achieve a homogeneous bubble-free coverage of surfaces to be treated.
DE 10 2004 021 532 describes a dispersion which, in addition to water, comprises 0.5 to 20% by weight of hydrophobic silica, 0.01 to 10% by weight of a gelling or viscosity-increasing additive, 0.1 to 1% by weight of a preservative and 0 to 1% by weight of a surface-active substance .
This dispersion can be used as insecticide against mites and other insects.
It is successfully used in spacious animal houses and on large surfaces, it being possible to use appropriately large-calibre sprayers (such as garden sprayers) for the spraying.
When used in the field of pets, where the area to be treated is rather small, large-calibre sprayers, such as, for example, garden sprayers, cannot be used.
In addition, pump spray bottles are not suitable because the necessary spraying pressure of more than 3 bar usually cannot be achieved. Accordingly, a good spray mist cannot be achieved and accordingly also a uniform covering of the cage area to be sprayed/treated cannot be achieved.
It is known to spray a pet cage area with a dispersion sold under the name "Decimite Aerosol".
This dispersion consists of an aqueous dispersion of a few percent of hydrophilic silica. This dispersion has the disadvantage that it takes too long to dry. Furthermore, it has an excessively high viscosity and also excessively poor spray formation.
Furthermore, because of the water content of the dispersion, the spray can has to be lacquered on the inside .
The object was accordingly to prepare a dispersion with an insecticidal action which can be satisfactorily sprayed on small surfaces and also can quickly develop its action.
A subject-matter of the invention is a dispersion comprising hydrophobic pyrogenically prepared silicon dioxide, alcohol and at least one additive which promotes the dispersing.
Use may be made, as hydrophobic pyrogenically prepared silicon dioxide, of: Aerosil® R805, Aerosil® R974, Aerosil® R202, Aerosil® R812, Aerosil® R812S and Aerosil® R8200.
Use may in particular be made of Aerosil® R812S.
The physicochemical characteristics of these pyrogenically prepared silicon dioxides are listed in Table 1.
Table 1
1} following DIN 66131
2) following DIN ISO 787/11, JIS K 5101/18 (not sieved)
3) following DIN ISO 787/2, ASTM D 280, JIS K 5101/21
4) following DIN 55921, ASTM D 1208, JIS K 5101/23
5) following DIN ISO 787/9, ASTM D 1208, JIS K 5101/24
7) based on the substance dried at 105 0 C for 2 hours
8) based on the substance ignited at 1000 0 C for 2 hours 10) in water : methanol = 1:1
11J HCl content is constituent of the loss on ignition 1 2) V product is supplied in bags of 15 kg net
The following can be used as alcohol: methanol, ethanol, propanol, isopropanol, 1-butanol, 2-methyl-l-propanol, 2-butanol and 2-methyl-2-propanol .
Use may in particular be made of low-boiling-point alcohols, such as, for example, ethanol.
In order to make possible good dispersing, it is, however, necessary to add an additive which promotes the dispersion, which additive covers remaining areas or new areas, not surface-modified, produced by the dispersing. The addition of hexamethyldisilazane (HMDS) has proven to be very advantageous for this.
The HMDS results, by this additional silanization, in a virtually perfect surface modification, through which a considerably lower viscosity is achieved. If appropriate, any excess HMDS can be converted by alcoholysis to give trimethylethoxysilane, trimethylsilanol or hexamethyldi- siloxane, and NH 3 .
Use may furthermore be made, as additive which promotes the dispersion, of other silanes which are likewise in a position to react with Si-OH groups still present on the Aerosil surface.
In principle, any silane is suitable which exhibits a satisfactory hydrophobic group but which in this connection does not introduce, through the silanization, any accessible additional silanol group. This can be achieved by having present only one group in the silane molecule capable of reacting with the SiOH group of the surface, thus an ROH or X group. Alternatively, the hydrophobic
"residue" of the silane molecule can have such a strong sterically shielding effect that an unreacted SiOH group of the silane molecule is not accessible.
Furthermore, the silane used should exhibit a high reaction rate. A satisfactory reaction rate may possibly be achieved by an increase in temperature.
Silazanes, and here in particular hexamethyldisilazane, have, due to the basic nature of the silazane group, a high affinity for SiOH surface groups. Only in the subsequent step is the trimethylsilyl group transferred. Trimethyl- silyl groups not reacted with SiOH surface groups are themselves inactivated by dimerization .
The following silanes can be used as additional silanes: a) organosilanes of the (RO) 3 Si(C n H 2n+I ) and (RO) 3 Si(C n H 2n -I) type
R = alkyl, such as, for example, methyl, ethyl, n- propyl, isopropyl or butyl, n = 1 - 20 b) organosilanes of the R' x (RO) y Si (C n H 2n+1 ) and R' x (RO) y Si (C n H 2n - I ) type
R = alkyl, such as, for example, methyl, ethyl, n-propyl, isopropyl or butyl
R' = alkyl, such as, for example, methyl, ethyl, n-propyl, isopropyl or butyl R' = cycloalkyl n = 1 - 20 x+y = 3 x = 1,2 y = 1,2 c) haloorganosilanes of the X 3 Si (C n H 2n+1 ) and X 3 Si (C n H 2n - I ) type
X = Cl, Br n = 1 - 20 d) haloorganosilanes of the X 2 (R' ) Si (C n H 2n+1 ) and X 2 (R') Si (C n H 2n - I ) type X = Cl, Br
R' = alkyl, such as, for example, methyl, ethyl, n-propyl, isopropyl or butyl
R'= cycloalkyl n = 1 - 20 e) haloorganosilanes of the X (R' ) 2 Si (C n H 2n+1 ) and
X(R 1 J 2 Si(C n H 2n -I) type X = Cl, Br
R' = alkyl, such as, for example, methyl, ethyl, n-propyl, isopropyl or butyl R' = cycloalkyl n = 1-20 f) organosilanes of the (RO) 3 Si (CH 2 ) m -R' type R = alkyl, such as methyl, ethyl or propyl m = 0, 1-20 R' = methyl, aryl (for example -C 6 H 5 , substituted phenyl radicals) -C 4 F 9 , OCF 2 -CHF-CF 3 , -C 6 F 13 , -0-CF 2 -CHF 2
-CH=CH 2 ,
g) organosilanes of the (R" ) x (RO) y Si (CH 2 ) m -R' type
R" = alkyl x+y = 3 = cycloalkyl x = 1,2 y = 1,2 m = 0, 1 to 20 R' = methyl, aryl (for example -C 6 H 5 , substituted phenyl radicals) -C 4 F 9 , -OCF 2 -CHF-CF 3 , -C 6 F 13 , -0-CF 2 -CHF 2
-CH=CH 2 ,
h) haloorganosilanes of the X 3 Si (CH 2 ) m -R' type
X = Cl, Br m = 0,1 - 20
R' = methyl, aryl (for example -C 6 H 5 , substituted phenyl radicals)
-C 4 F 9 , -OCF 2 -CHF-CF 3 , -C 6 F 13 , -0-CF 2 -CHF 2
-CH=CH 2 ,
i) haloorganosilanes of the (R) X 2 Si (CH 2 ) m -R' type X = Cl, Br
R = alkyl, such as methyl, ethyl or propyl m = 0,1 - 20 R' = methyl, aryl (e.g. -C 6 H 5 , substituted phenyl radicals)
-C 4 F 9 , -OCF 2 -CHF-CF 3 , -C 6 F 13 , -Q-CF 2 -CHF 2
-CH=CH 2
j) haloorganosilanes of the (R) 2 X Si(CH 2 ) m -R' type
X = Cl, Br R = alkyl m = 0,1 - 20
R' = methyl, aryl (e.g. -C 6 H 5 , substituted phenyl radicals)
-C 4 F 9 , -OCF 2 -CHF-CF 3 , -C 6 F 13 , -0-CF 2 -CHF 2 -CH=CH 2 ,
k) silazanes of the R 1 R 2 Si-N-SiR 2 R' type
H R = alkyl, aryl R' = alkyl, aryl
1) cyclic polysiloxanes of the D3, D4 and D5 type, D3, D4 and D5 being understood as meaning cyclic polysiloxanes with 3, 4 or 5 units of the -O-Si (CH 3 ) 2 - type. E.g. octamethylcyclotetrasiloxane = D4
(m) polysiloxanes or silicone oils of the type
Y-O- -20
Si (CH 3 ) 2 0H, Si (CH 3 ) 2 (OCH 3 ) Si (CH 3 ) 2 (C n H 2n+1 ) n=l-20
R alkyl , such as C n H 2n+1 , in which n = 1 to 20, aryl, such as phenyl and substituted phenyl radicals, H
R' = alkyl , such as C n H 2n+1 , in which n = 1 to 20, aryl, such as phenyl and substituted phenyl radicals, H,
R" = alkyl , such as C n H 2n+1 , in which n = 1 to 20, aryl, such as phenyl and substituted phenyl radicals, H
R'" = alkyl , such as C n H 2n+1 , in which n = 1 to 20, aryl, such as phenyl and substituted phenyl radicals, H
Hydrophobic pyrogenically prepared silicon dioxides can be very well dispersed in alcohols since these are wetted with alcohols.
Furthermore, rapid drying of the sprayed surfaces/cage areas is achieved by the use of in particular highly volatile alcohols, such as ethanol or isopropanol. The lethal action also starts more quickly through this.
Rheology-modifying additives can be added for satisfactory adhesion of the Aerosil to the surfaces/cage areas to be covered and in order to prevent the sprayed-on dispersion from flowing off. Such additives can be alcohol-soluble
modified celluloses.
Hydroxypropylcellulose (HPC) can in particular be used for this since it is satisfactorily soluble in alcohols.
The hydroxypropylcellulose can exhibit a molecular weight of less than 1 000 000.
In a preferred embodiment of the invention, the hydroxypropylcellulose can exhibit a molecular weight of 5000 to 500 000, in particular 80 000 ± 20 000.
It can be seen from the examples that the amounts of the rheology-modifying agent used also affects the activity of the dispersion. This amount used can be limited by the product of the average molecular weight of the hydroxypropylcellulose and the concentration in % by weight. It can be less than 250 000.
HPC with an excessively high molecular weight of more than 1 000 000 results in a high structural viscosity which not only leads to a poor ability to be sprayed but also contributes to a reduction in the mortality.
With the dispersion according to the invention, it is possible, by the use of alcohol, to dispense with an addition of additives for the preservation of the hydroxypropylcellulose employed.
In a particularly preferred embodiment of the invention, the dispersion according to the invention can be composed of hydrophobic pyrogenically prepared silicon dioxide, alcohol and an additive which promotes the dispersion. If appropriate, the preferred dispersion can additionally comprise a rheology-modifying additive.
The dispersion according to the invention can be used as insecticide, in particular for combating mites.
The dispersions according to the invention can be
satisfactorily sprayed with propellent gas sprays.
An additional advantage of the alcoholic dispersion according to the invention is caused by the fact that the alcohol does not have a corrosive effect on the metals used in spray cans. Internal lacquering of the cans can accordingly be dispensed with.
An additional subject-matter of the invention is a spray can which comprises the dispersion according to the invention .
This spray can can additionally comprise a propellent.
Use may be made, as propellent, of propane, butane or a mixture of propane and butane with a proportion of propellent gas of 10 to 80%.
Nitrogen or nitrous oxide can be used as propellent gas.
The pressure necessary for the spraying can be produced by a pump system.
Examples
Determination of the viscosity of the dispersions
The viscosity of the dispersions produced was determined using a rotational rheometer from Physica Model 300 and the measuring cup CC 27 at 25°C.
Determination of the activity (mortality) against adult mites
In order to determine the action (mortality) on completely saturated adult mites, in each case approximately 100 mites are deposited on a dried active substance coating (wet film thickness 200 μm) on galvanized sheet steel in a plastic petri dish which, after closing with a fine web/gauze, is stored in a climate-controlled chamber (23°C and variable
relative air humidity) . After, for example, 24 h, the living, injured or dead mites are counted under a stereomicroscope . The test is carried out at 50% and 100% relative air humidity. In order to achieve a uniform layer thickness on using the spray, a sufficient amount is sprayed into a glass and the dispersion is applied with a doctor blade (wet film thickness 200 μm) .
Example 1
798 g of ethanol are introduced and 2 g of HMDS (hexamethyldisilazane) are added. 200 g of Aerosil® R812S are then incorporated with stirring using a high-speed laboratory stirrer (jacketed dispersion containers, Dispermat® dissolver from VMA-Getzmann GmbH, toothed disc with a diameter of 70 mm) and subsequently dispersed at 2200 rpm for 15 minutes. 6.66 g of HPC (hydroxypropyl cellulose with a molar mass M of approximately 80 000 from Sigma-Aldrich) are subsequently added. The mixture is subsequently diluted with an additional 327 g of ethanol to an Aerosil® R812S content of 15%. Finally, the mixture is dispersed at 1000 rpm for 15 minutes, resulting in the dissolution of the hydroxypropyl cellulose.
This corresponds to a concentration of use with the HPC of 0.5% by weight. With a molecular weight of 80 000, this results in a product % x M of 40 000.
This dispersion exhibits the viscosity curve represented in Figure 1.
This dispersion is bottled in spray bottles and placed under pressure with a propane/butane mixture. Good spray formation can be produced. This means that a uniform coating of a surface is possible.
This spray can now be used for the spraying of cage areas occupied by mites.
The Aerosil® R812S used is a pyrogenically prepared silicon dioxide with the physicochemical characteristics given in Table 1.
Result:
After 24 h and 50% relative humidity, a mortality of 100% is achieved. This is an excellent activity.
Example 2
798 g of ethanol are introduced and 2 g of HMDS (hexamethyldisilazane) are added. 200 g of Aerosil® R812S are then incorporated with stirring using a high-speed laboratory stirrer (jacketed dispersion containers, Dispermat® dissolver from VMA-Getzmann GmbH, toothed disc with a diameter of 70 mm) and subsequently dispersed at 2200 rpm for 15 minutes. 4.00 g of HPC (hydroxypropyl cellulose with a molar mass M of approximately 370 000 from Sigma-Aldrich) are subsequently added. The mixture is subsequently diluted with an additional 329.7 g of ethanol to an Aerosil® R812S content of 15%. Finally, the mixture is dispersed at 1000 rpm for 15 minutes, resulting in the dissolution of the hydroxypropyl cellulose.
This corresponds to a concentration of use with the HPC of 0.3% by weight. With a molecular weight of 370 000, this results in a product % x M of 111 000.
This dispersion exhibits the viscosity curve represented in Figure 2.
This dispersion is now bottled in spray bottles and placed under pressure with a propane/butane mixture. Good spray formation can be produced. This means that a uniform coating of a surface is possible.
This spray is now be used for the spraying of cage areas occupied by mites.
Re sul t :
After 24 h and 50% relative humidity, a mortality of 67% is achieved. This is a limited activity.
Example 3
798 g of ethanol are introduced and 2 g of HMDS
(hexamethyldisilazane) are added. 200 g of Aerosil® R812S are then incorporated with stirring using a high-speed laboratory stirrer (jacketed dispersion containers, Dispermat® dissolver from VMA-Getzmann GmbH, toothed disc with a diameter of 70 mm) and subsequently dispersed at 2200 rpm for 15 minutes. 1.66 g of HPC (hydroxypropyl cellulose with a molar mass M of approximately 1 000 000 from Sigma-Aldrich) are subsequently added. The mixture is subsequently diluted with an additional 332 g of ethanol to an Aerosil® R812S content of 15%. Finally, the mixture is dispersed at 1000 rpm for 15 minutes, resulting in the dissolution of the hydroxypropyl cellulose.
This corresponds to a concentration of use with the HPC of 0.125% by weight. With a molecular weight of 1 000 000, this results in a product % x M of 125 000.
This dispersion exhibits the viscosity curve represented in Figure 3.
This dispersion is now bottled in spray bottles and placed under pressure with a propane/butane mixture. Good spray formation can be produced. This means that a uniform coating of a surface is possible.
This spray was used for the spraying of cage areas occupied by mites.
Result:
After 24 h and 50% relative humidity, a mortality of 93% is achieved. This is a good activity.
Comparative example
798 g of ethanol are introduced and 2 g of HMDS (hexamethyldisilazane) are added. 200 g of Aerosil® R812S are then incorporated with stirring using a high-speed laboratory stirrer (jacketed dispersion containers,
Dispermat® dissolver from VMA-Getzmann GmbH, toothed disc with a diameter of 70 mm) and subsequently dispersed at 2200 rpm for 15 minutes. 6.66 g of HPC (hydroxypropyl cellulose with a molar mass M of approximately 1 000 000 from Sigma-Aldrich) are now added. The mixture is subsequently diluted with an additional 327 g of ethanol to an Aerosil® R812S content of 15%. Finally, the mixture is dispersed at 1000 rpm for 15 minutes and the HPC is dissolved.
This corresponds to a concentration of use with the HPC of 0.5% by weight. With a molecular weight of 1 000 000, this results in a product % x M of 500 000.
This dispersion exhibits the viscosity curve represented in Figure 4.
This dispersion is now bottled in spray bottles and placed under pressure with a propane/butane mixture. Due to the high viscosity, good spray formation cannot be achieved. This means that a uniform coating of a surface is not possible .
Result:
After 24 h and 50% relative humidity, a mortality of 24% is now achieved. This is a poor activity.