DE102009022516A1 - Hydrophobic sand, method of making and using same - Google Patents

Abstract

The invention relates to a method for producing hydrophobic sand, the hydrophobic sand itself and its use. Sand of any particle size below 2000 microns sand particle size can be water repellent equipped with silanizing agent emulsions according to the invention. For this purpose, from 0.19 × 10 5 to 10 × 10 g of a silanizing agent per minute of surface are used according to the invention.

Description

In Increasingly, the world of devastation and is Water shortage affected. Especially in agricultural and But horticultural applications will be one for growth the respective plants needed sufficient amount of water. It is therefore essential agricultural or horticultural land with a sufficient amount of water. Also for the reclamation of previously unused land area sufficient amounts of water are needed.

With Help of channels, irrigation, artificial Sprinkling or similar can provide water to the intended Jobs transported and deployed. However, you have to the irrigated soils a certain amount of water Save for as long as possible to save money to achieve sufficient plant growth.

One way to improve the water retention capacity is to change the soil itself, to prevent the seepage of water. As in DE 4325692 For this purpose, an artificial soil structure can be produced which has water-repellent properties. A disadvantage of the mentioned application is that the silicone-modified sands used therein do not have sufficient long-term stability in an acidic and alkaline medium, while the sands treated with fluorinated substituents are ecologically unacceptable because of the lack of biodegradability of such fluorinated compounds.

In WO 0232213 . US 6060557 and EP 1591476 describes the use of organic polymers (especially cross-linked acrylates) to equip soils with water-retaining layers for agriculture. The lack of chemical bonding of such layers to the sand matrix and the lack of UV stability of organic polymers ( Rånby, Journal of Analytical and Applied Pyrolysis 1989, 15, 237-247 In general, however, the durability of the treatment is questionable.

In JP 2000-023559 describes the preparation and use of sand treated with alkyd resins or silicones. The disadvantage is that a larger number of organic reaction resins and crosslinkers, and Si-containing starting materials is needed. In addition, in the bonded with organic resins sandy soils plants can no longer root and plant growth is therefore limited. The sands described there are accordingly called "non-grass" soils.

In WO 9841408 The production and use of beeswax-containing agents modified sand is described. A disadvantage of the material thus obtained lies in the stickiness caused by the beeswax, which is suitable for modeling purposes, but hindered in agricultural applications.

Naturally also the possibility is used, soil particles water repellent (hereinafter also called hydrophobing) equip.

In JP 07-048559 the production of silanized inorganic materials is described. The disadvantage lies in the necessary use of chlorosilanes in organic solvents for the preparation of the materials described.

In JP 07-194286 describes the preparation and use of a sand material which has been treated with a silane compound. The available sand can be used to prevent the growth of weeds. The paper assumes that the effect of the treated sand is due to the fact that the treated sand can no longer store water and thus prevent the growth of aerial seeds. The disadvantage of the described material is that the growth of plants is prevented and no more favorable conditions for the growth of useful plants are created. In addition, the required dosage must be determined by tests and can not be determined on the basis of the properties of the sand to be treated.

The Object of the present invention is therefore to provide a water-repellent To provide sand in a simple way, using small amounts of silanizing agent can be. This task is performed according to the independent Claims solved and in more detail below explained.

Surprisingly, it was found that sand can be water repellent equipped with a low consumption of aqueous Si-containing compounds, the amount required depending on the mean particle size of the sand particles.

The Sand particles are inventively with a made suitable water repellent suitable hydrophobizing agent. invention Hydrophobizing agents are Si-containing compounds, for example Silanes, siloxanes and / or silicones. These are referred to below as silanizing agents called. The aqueous emulsions or aqueous Solutions of these silanizing agents are described below Called silanizing agent emulsions.

• (a) Bereitstellen von Sand,
• (b) Entfernen von Grobanteilen mit einer mittleren Sandpartikel Größe > 2000 μm, und anschließend
• (c) Bestimmung der Schüttdichte, der mittleren Größe der Sandpartikel, und der inneren Oberfläche_Sand des nach Schritt (b) erhaltenen Sandes, und anschließend
• (d) Mischen des nach Schritt (c) erhaltenen Sandes mit Silanisierungsmittel-Emulsion in einem Mischaggregat in einer Menge von 0,19·10^–2 bis 5,0·10^–2 (g Silanisierungsmittel)/(m² innere Oberfläche_Sand) bei einer Drehzahl von 500 U/min–4000 U/min während einer Zeitdauer von 1 bis 10 min, und anschließend
• (e) Trocknen während 0,5 bis 2 h bei einer Temperatur von 30 bis 90°C.

The subject matter of the present invention is therefore a process for producing hydrophobic sand which comprises the steps:

• (a) providing sand,
• (b) Removal of coarse particles with a mean sand particle size> 2000 microns, and then
• (c) determining the bulk density, the average size of the sand particles, and the inner surface _{sand of} the _{sand obtained} after step (b), and subsequently
• (d) mixing the sand obtained after step (c) with silanizing agent emulsion in a mixing unit in an amount of 0.19 × 10 ^-2 to 5.0 × 10 ^-2 (g silanizing agent) / (m ² inner surface _sand ) at a speed of 500 rpm-4000 rpm for a period of 1 to 10 minutes, and subsequently
• (e) drying for 0.5 to 2 hours at a temperature of 30 to 90 ° C.

When Sand can be used for all types of sands, such as Quartz sands, River or sea sands, sands or minerals into consideration come. Suitable sands can be particle sizes from 150 μm to 2000 μm, preferably from 200 μm to 2000 μm, more preferably from 300 μm to 1800 μm to have.

in der R¹ C₁-C₁₈-Alkyl ist, Gruppen R² gleich oder verschieden sind und R² ein Wasserstoffatom oder ein Alkylrest mit 1 bis 6 Kohlenstoffatomen, vorzugsweise mit 1 oder 2 Kohlenstoffatomen, ist.According to the claimed method silanizing agents are therefore used for the water-repellent finishing of sand. Such silanizing agents may include alkyl-substituted silanes of general structure I,

wherein R ^{1 is} C ₁ -C ₁₈ alkyl, groups R ^{2 are the} same or different and R ^{2 is} a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, preferably 1 or 2 carbon atoms.

Preferred examples are those with radicals:
R ¹ = CH ₃ -, C ₂ H ₅ -, C ₃ H ₇ -, C ₄ H ₉ -, iC ₄ H ₉ -, C ₆ H ₁₃ -, iC ₆ H ₁₃ , C ₈ H ₁₆ -, iC ₈ H ₁₆ - and
R ² = H, methyl or ethyl.

in der Gruppen R¹ und R³ unabhängig voneinander C₁-C₁₈-Alkyl sind, welche ein oder mehrere Heteroatome wie N, O, F, Cl, P oder S enthalten können, Gruppen R² gleich oder verschieden sind und R² ein Wasserstoffatom oder ein Alkylrest mit 1 bis 6 Kohlenstoffatomen, vorzugsweise mit 1 oder 2 Kohlenstoffatomen, ist und n + m den Oligomerisierungsgrad als mit 2 bis 50, bevorzugt 2 bis 30, bestimmt, ausgewählt werden. Es handelt sich hierbei vorteilhaft um Oligomerengemische mit einem mittleren Oligomerisierungsgrad von 2 bis 50, vorzugsweise von 2 bis 30, wobei die mittlere Molmasse bevorzugt 300 bis 10000 g/Mol beträgt. Die Silanoligomeren der allgemeinen Formel II können dabei als lineare, cyclische und/oder verzweigte Einheiten vorliegen.Such silanizing agents may moreover comprise oligomeric siloxanes or silanoligomers of the idealized general structure II,

in the groups R ¹ and R ^{3 are} independently C ₁ -C ₁₈ alkyl, which may contain one or more heteroatoms such as N, O, F, Cl, P or S, groups R ^{2 are the} same or different and R ² a Is hydrogen atom or an alkyl group having 1 to 6 carbon atoms, preferably 1 or 2 carbon atoms, and n + m is the degree of oligomerization as being 2 to 50, preferably 2 to 30, determined. These are advantageously oligomer mixtures having a mean degree of oligomerization of from 2 to 50, preferably from 2 to 30, the average molecular weight preferably being from 300 to 10 000 g / mol. The silanoligomers of the general formula II can be present as linear, cyclic and / or branched units.

Preferred examples of silanoligomers are those having radicals:
R ¹ = CH ₃ -, C ₂ H ₅ -, C ₃ H ₇ -, C ₄ H ₉ -, iC ₄ H ₉ -, C ₆ H ₁₃ -, iC ₆ H ₁₃ , C ₈ H ₁₆ -, iC ₈ H ₁₆ - and
R ² = H, methyl or ethyl.

in der die Gruppen R⁴ gleich oder verschieden sind und ein Wasserstoffatom oder ein Alkylrest mit 1 bis 6 Kohlenstoffatomen, vorzugsweise mit 1 oder 2 Kohlenstoffatomen sind und o den Polymerisierungsgrad als mit 5 bis 5000, bevorzugt 20 bis 1000, angibt. Bevorzugte Beispiele sind solche mit Resten
R⁴ = H-, CH₃-, C₂H₅-.Finally, such silanizing agents may also comprise polymeric silicones of the idealized general formula III,

in which the groups R ^{4 are} identical or different and are a hydrogen atom or an alkyl radical having 1 to 6 carbon atoms, preferably having 1 or 2 carbon atoms and o indicates the degree of polymerization as from 5 to 5000, preferably 20 to 1000. Preferred examples are those with radicals
R ⁴ = H-, CH ₃ -, C ₂ H ₅ -.

The Silanization agents are used according to the invention as aqueous emulsion or used as an aqueous solution.

The Silanizing agent emulsions used according to the invention have a silanizing agent content of 0.5-99.9 w%, preferably from 1-99 w%, more preferably from 2.5-99 w%, most preferably from 5-80 w%. The unit w% is based on the total mass of the formulation.

It may be advantageous if the silanizing agent emulsion according to the invention additionally contains, as aqueous emulsion, at least one emulsifier which is advantageously selected from the series of alkyl sulfates with C ₈ -C ₁₈ -alkyl, alkyl and alkaryl ether sulfates with C ₈ -C ₁₈ -alkyl in the hydrophobic And with 1 to 40 ethylene oxide (EO) - or propylene oxide (PO) - units alkyl sulfonates with C ₈ -C ₁₈ alkyl, alkaryl sulfonates with C ₈ -C ₁₈ alkyl, and half esters of sulfosuccinic acid with monohydric alcohols or alkylphenols with 5 to 15 carbon atoms, alkali metal and ammonium salts of carboxylic acids having 8 to 20 carbon atoms in the alkyl, aryl, alkaryl or aralkyl radical, alkyl and alkaryl phosphates having 8 to 20 carbon atoms in the organic radical, alkyl ether or alkaryl ether phosphates having 8 to 20 Carbon atoms in the alkyl or alkaryl radical and 1 to 40 EO units, alkyl polyglycol ethers and alkaryl polyglycol ethers having 8 to 40 EO units and C ₈ -C ₂₀ carbon atoms in the Alkyl or aryl radicals, ethylene oxide / propylene oxide (EO / PO) block copolymer having 8 to 40 EO or PO units, addition products of alkylamines having C ₈ -C ₂₂ -alkyl radicals with ethylene oxide or propylene oxide, alkyl polyglycosides with linear or branched saturated or unsaturated C ₈ -C ₂₄ -alkyl radicals and Oligoglykosidresten with 1 to 10 hexose or pentose units, silicon-functional surfactants or mixtures of these emulsifiers is selected.

Of the Content of emulsifier in such inventively used Composition is preferably 0.01 to 5 wt .-%, based on total weight of the emulsion.

Further may be used according to the invention silanizing agent emulsions at least one hydrolysis or condensation catalyst from the Series of complex compounds, such as halides, oxides, hydroxides, Imides, alcoholates, amides, thiolates, carboxylates and / or combinations of these substituents, of elements of the 3rd and 4th main group of the Periodic Table of the Elements (PSE) and of subgroups II, III, IV, V, VI, VII and VIIIa, VIIIb and VIIIc of the PSE, in particular Titanates or zirconates, such as tetra-n-butyl orthotitanate or tetra-n-propylorthozirconate. In addition, you can Oxides, hydroxides, hydrogen phosphates, hydrogen sulfates, sulfides, hydrogen sulfides, Carbonates or bicarbonates of the 1st and 2nd main group of the PSE and / or alcoholates, preferably sodium methoxide or sodium ethoxide and / or Amino alcohols, preferably 2-aminoethanol or 2- (N, N-dimethyl) aminoethanol be used.

After all can carboxylic acids such as formic acid, Acetic or propionic acid and mineral acids such as hydrochloric acid or phosphoric acid are used.

About that In addition, the silanizing agent emulsion used according to the invention advantageously still conventional adjuvants selected from inorganic or organic acids, buffer substances, Fungicides, bactericides, algicides, microbiocides, fragrances, Corrosion inhibitors, preservatives, rheology aids contain.

The silanizing agent emulsions used according to the invention can advantageously be further diluted with water before use. In principle, all types of water such as deionized water, drinking water, wastewater or seawater are suitable. Diluents which can be used according to the invention comprise 1 part of silanizing agent emulsion and 0 to 99 parts of water, preferably 1 part of silanizing agent emulsifier and 0.1 to 49 parts of water, most preferably 1 part silanizing agent emulsion and 1 to 9 parts of water.

in the Step (b) of the method according to the invention is the sand to be treated is first sifted to coarse fractions with a mean sand particle size> 2000 μm too remove.

The Grain sizes of the sand can be determined by air classification, Classify, sieve the sand or by a combination of these Methods are limited.

Subsequently, in step (c), the bulk density and the average size of the sand particles are determined in a manner known to those skilled in the art. In the process according to the invention, the silanizing agent emulsion is now used in an amount of 0.19 × 10 ^-2 to 5.0 × 10 ^-2 (g of silanizing agent) / (m ^{2 of} internal surface _sand ).

The term "inner surface of _sand " is understood here and below as the quotient of the volume of sand used and the mean volume of a sand particle multiplied by 0.74 and the mean surface of the sand particle. Average volume and mean surface area of a sand particle are also determined in a manner known to those skilled in the art, assuming approximately spherical particles of sand. Thus, the inner surface _sand can be calculated from the mean sand particle size and the bulk density of the sand and over the volume and the surface of the individual sand particles.

In step (d) of the process according to the invention, the silanizing agent emulsion sand obtained after step (c) is added in an amount of 0.19 × 10 ^-2 to 5.0 × 10 ^-2 (g silanizing agent) / (m ² inner surface area) _Sand ) at a speed of 500 rpm 4000 rpm for a period of 1 to 10 minutes.

In the process according to the invention, preferably from 0.5 × 10 ^-2 to 3.5 × 10 ^-2 , particularly preferably from 1.0 × 10 ^-2 to 3.0 × 10 ^-2 (g silanizing agent) / (m ² inner Surface _sand ) are used.

Of the sand to be treated becomes in step (d) at a speed of 500 Rpm 4000 rpm with the silanizing agent emulsion mixed in a suitable mixing unit. It will be during a period of 1 to 10 minutes mixed at this speed.

When Mixing unit can be an internal mixer, for example, a Lödigemischer, a cone mixer, a stirred tank, kneader, blender, to only to give some examples. Suitable mixing units are advantageous ones, which during the mixing process, the sand particles do not break into smaller particles. Preferably, mixing units to choose their energy input in the composition from sand and silanizing agent emulsion neither chemical, nor causes physical transformations in the volumes of the sand particles.

It may furthermore be advantageous, the speed after a period of time t1 from 1 to 10 minutes to increase by a factor of 1.5-4 and the speed then reached during a period of time t2 of 0.5 to 120 minutes to maintain.

A Such an approach has the advantage that the inventively used Silanizing agent emulsion with the sand or with the surface the sand particles more fully implemented and thus the durability the hydrophobicity of the sand is increased.

Of the Sand obtained after step (d) is then in step (e) the process of the invention during 0.5 to 2 h at a temperature of 30 to 90 ° C, preferably dried at 40 to 80 ° C. This can be the heat by an oven, a heat lamp or by sunlight will be realized.

Especially offers the possibility of drying by solar radiation, especially in desert areas, big advantages in practical application in terms of energy savings.

Prefers For example, the sand obtained after step (d) may be grown on a large scale Area to be distributed to the largest possible Amount according to the steps (a) to (d) treated Sand particles at the same time the sun exposure.

With These options are the method according to the invention especially economical, combined with both options most economical feasible.

Of the Advantage of the claimed method lies in intimate mixing the sand particles with the silanizing when known necessary Dosage. By the method according to the invention Ensures that the sand is a maximum water repellent Effect with minimal amount of silanizing agent to be used receives.

object The invention is therefore also hydrophobic sand, which after the process according to the invention is obtained.

Also is the subject of the invention hydrophobic sand in which the seepage is reduced by water or does not take place.

After all is also the subject of the present invention the use of the hydrophobic sand according to the invention in one Soil structure, as well as landscaping, in horticulture, in the erosion protection of soil layers, as evaporation barrier of the Soil water, as a barrier against the infiltration of water for the irrigation of useful and / or ornamental plants, in agriculture.

Advantageous in the use according to the invention it is that the invention treated and dried hydrophobic sand on each designated area deploy and distribute easily evenly. It is also possible and can be done in many cases be meaningful, first one or more layers of remove the surface to be treated and then the water-repellent To spread sand. Finally, it is advantageously possible the applied, treated sand with one or more soil layers again to cover. In this way one can benefit the Avoid erosion of the treated sand by wind or water.

The The present invention will be further described by way of examples explained.

Example 1:

Quartz sand H 32 (CAS: 14808-60-7, mean particle size: 0.32 mm, apparent density according to DIN EN 1097-3 : 1.515 g / cm ³ ) was treated in a Lödigemischer with a dilute aqueous emulsion of an ethoxy-substituted propylsiloxane (average molecular weight between 500 and 900 g / mol, proportion of siloxane about 50%, hereinafter referred to as E).

To 2.5 kg of quartz sand were submitted in Lödigemischer.

The aqueous emulsion E was in a ratio of 1 part E: 9 parts of water diluted with the silanizing agent emulsion was obtained. 6.6 ml of this diluted emulsion were then added dropwise with a pipette. For Mixing was carried out at 1575 rpm for 10 minutes, then at 5 minutes 2800 rpm. The thus treated quartz sand was subsequently dried for 2 h at 80 ° C.

Subsequently For example, a water sink test, described below, was performed.

Example 2:

As Example 1, but the silanizing agent emulsion was thereby get that E in higher concentration, 1 part E: 4 Parts of water, was used.

The Effectiveness of the hydrophobization was determined by means of a water sink test checked as described below.

Comparative Example:

Fine sand (desert sand from Dubai, mean particle size: 100 μm, bulk density: 1.541 g / cm ³ ) was treated with E in a Lödigemischer.

To were submitted 1.5 kg of fine sand in Lödigemischer and 3.82 g of the silanizing agent emulsion obtained from a dilution from 1 part E with 9 parts water, added.

For 10 minutes was mixed at 1575 rpm. The treated fine sand was then dried for 2 h at 80 ° C.

The Effectiveness of the hydrophobization was determined by means of a water sink test checked as described below. The so treated Sand is not hydrophobic in this test.

Example 3:

As in the comparative example, but according to the invention 200th g of fine sand with 2.11 g silanizing agent emulsion from E in a dilution of 1 part E to 9 parts water, treated, and then performed the water sinking test.

Example 4:

As in the comparative example, but according to the invention 1000 g of a coarse sand (desert sand from Dubai, average grain size: 500 microns, bulk density: 1.64 g / cm ³ ) with 2.48 g silanizing agent emulsion obtained from E in a dilution of 1 Part E to 9 parts of water, treated, and then performed the Wasserversenkungstest.

Water immersion test

sand is filled into an aluminum bowl about 1 cm high and lightly pressed firmly by hand, leaving the sand has a horizontal surface. At two Make 2 drops of water on this surface distilled water with a drop diameter of 5 mm by means of put on a pipette. The drops of water are at a distance of at least one drop diameter. You leave that Experimental setup under ambient conditions (20 ° C, 1013 hPa) are open and observe the drops of water over a period of a few hours. The time periods are measured until the end of both drops of water in each case in the sand completely are seeped. The durations become the arithmetic mean formed, which is called residence time in the following.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 4325692 [0003]
• WO 0232213 [0004]
• - US 6060557 [0004]
• EP 1591476 [0004]
• - JP 2000-023559 [0005]
• WO 9841408 [0006]
• - JP 07-048559 [0008]
• JP 07-194286 [0009]

Cited non-patent literature

• B. Rånby, Journal of Analytical and Applied Pyrolysis 1989, 15, 237-247 [0004]
• - DIN EN 1097-3 [0048]

Claims (12)

A process for producing hydrophobic sand, comprising the steps of: (a) providing sand, (b) removing coarse particles having a mean sand particle size> 2000 μm, and then (c) determining the bulk density, the mean size of the sand particles, and inner surface _{sand of} the _{sand obtained} after step (b), and then (d) mixing the sand obtained after step (c) with silanizing agent emulsion in a mixing aggregate in an amount of 0.19 × 10 ^-2 to 5.0 × 10 ^-2 (g silanizing agent) / (m ² inner surface _sand ) at a speed of 500 rpm 4000 rpm for a period of 1 to 10 minutes, and then (e) drying for 0.5 to 2 hours a temperature of 30 to 90 ° C. Method according to claim 1, characterized in that that in step (a) the sand is selected from quartz sands, River sands, sea sands, sands, minerals or a mixture from these sands. Method according to one of claims 1 or 2, characterized in that after step (b) and before step (c) the grain sizes of the sand to 150 microns be brought to 2000 microns. Method according to claim 3, characterized that the particle sizes by air classification, classifying, Seven of the sand or limited by a combination of these methods become. Method according to at least one of the claims 1 to 4, characterized in that in step (d) as a silanizing agent in the silanizing agent emulsion, an aqueous emulsion of silanes of structure I, an aqueous emulsion of Siloxanes of Structure II, an aqueous emulsion of silicones the structure III, or a mixture of these emulsions becomes. Method according to claim 5, characterized in that that the sand in a mixing unit, selected from Lödigemischer, is added with the silanizing agent emulsion. Method according to claim 5 or 6, characterized, that in step (d) first during a period of time from 1 to t1 at a speed D1, and then while a time period of t2 is mixed at a rotational speed D2, wherein 1 <t1 <10 min, and 0.5 <t2 <120 min, and 500 Rpm ≤ D1 <D2 ≤ 4000 U / min. Method according to at least one of the claims 1 to 7, characterized in that in step (e) as a heat source Sunlight is used. Method according to at least one of the claims 1 to 8, characterized in that in step (e) the step (d) distributed sand spread over a large area becomes. Hydrophobic sand obtained by a process according to at least one of claims 1 till 9. Hydrophobic sand, characterized in that Water immersion test patch drops of water a residence time of at least 3 min on the horizontal surface of the Have sand. Use of hydrophobic sand after at least one of claims 1 to 11 in soil structures, in landscaping, in horticulture, in erosion protection of soil layers, as evaporation barrier of groundwater, as a barrier against the infiltration of water for the irrigation of useful and / or ornamental plants, in agriculture.