JP2012527870A - Hydrophobic sand, its production method and use - Google Patents

Abstract

The subject of the present invention is a method for producing hydrophobic sand, the hydrophobic sand itself and its use. Each sand having a particle size of less than 2000 μm is finished to be water repellent with the silanizing agent-emulsion according to the present invention. To this end, 0.19 · 10 ^{−2 to} 5 · 10 ⁻² g of silanizing agent per internal surface area m ² is used according to the invention.

Description

  The world is increasingly suffering from devastation and water shortages. However, in agricultural and horticultural applications, a sufficient amount of water is required for the growth of each plant. Accordingly, it is indispensable to supply a sufficient amount of water to agricultural or horticultural land. A sufficient amount of water is also required for the land reclamation, which has not been used in the past.

  Water can be transported to the planned location and watered using waterways, irrigation equipment, artificial sprinklers or similar means. However, in order to achieve economically sufficient plant growth, this irrigated soil must store a predetermined amount of water for as long as possible.

  One means to improve water retention capacity is to modify the soil itself so that water penetration is impeded. For this purpose, an artificial soil structure with water-repellent properties can be created, as described in DE 4325692. The disadvantage of the mentioned application is that the silicone-modified sand used here does not have sufficient storage stability in acidic and alkaline media, while sand treated with this fluorinated material does not The lack of environmental concerns due to the lack of biodegradability of such fluorinated compounds.

  WO 0232213, US 6060557 and EP 1591476 describe the use of organic polymers (especially cross-linked acrylates) to provide a water retention layer on soil for agriculture. However, this layer lacks chemical bonding to the sand matrix and lacks the UV stability of organic polymers (B. Ranby, Journal of Analytical and Applied Pyrolysis 1989, 15, 237-247.). In general, the persistence of this process is questionable.

  JP 2000-023559 describes the production and use of sand treated with alkyd resins or silicones. The disadvantage is that a large number of organic reaction resins and crosslinkers and Si-containing starting materials are required. In addition, plants can no longer root in sand soils glued with organic resins, thus limiting plant growth. The sand described here is correspondingly referred to as “non-glass” soil.

  WO 9841408 describes the production and use of sand modified with beeswax-containing agents. The disadvantages of the material thus obtained are caused by beeswax and are inadequate adhesion for agricultural applications while being suitable for modeling purposes.

  Of course, means for finishing the soil particles to be water repellent (hereinafter also referred to as hydrophobic) is also used.

  JP 07-048559 describes the production of silanized inorganic materials. The disadvantage is that the production of the described material requires the use of chlorosilane in an organic solvent.

  JP 07-194286 describes the production and use of sand materials treated with silane compounds. This resulting sand can be used for the prevention of weed growth. In this publication, it is assumed that the action of this treated sand is based on the fact that this treated sand can no longer store water, thereby preventing the flying seeds from taking root. The disadvantages of the described materials are that plant growth is hindered and favorable conditions are not achieved by growth of useful plants. In addition, the required metering quantity must be calculated by testing and cannot be determined based on the characteristics of the sand to be treated.

  Accordingly, an object of the present invention is to provide water-repellent sand that can be easily produced using a small amount of silanizing agent. This problem is solved by the independent claims and is described in detail below.

  Surprisingly, it has been found that sand can be made water-repellent with the use of small amounts of aqueous Si-containing compounds, the required amount depending on the average particle size of the sand particles.

  The sand particles are rendered water repellent with a suitable hydrophobizing agent according to the present invention. The hydrophobizing agents according to the invention are Si-containing compounds such as silanes, siloxanes and / or silicones. These are hereinafter referred to as silanizing agents. This aqueous emulsion or aqueous solution of silanizing agent is hereinafter referred to as silanizing agent-emulsion.

That is, the subject of the present invention consists of the following steps:
(A) a step of preparing sand;
(B) removing the coarse content having an average sand particle size> 2000 μm, and subsequently
(C) the step of measuring the bulk density of the sand obtained by step (b), the average particle size of the sand particles and the internal surface area _sand , and subsequently
(D) the sand obtained by step (c) together with the silanizing agent-emulsion in a mixing device,
0.19 · 10 ^{−2 to} 5.0 · 10 ⁻² (g silanizing agent) / (m ² internal surface area _sand )
At a rotational speed of 500 rpm to 4000 rpm,
Mixing for 1 to 10 minutes, and subsequently
(E) It is a manufacturing method of hydrophobic sand including the process of drying at the temperature of 30-90 degreeC for 0.5 to 2 hours.

  All types of sand can be considered as sand, such as quartz sand, river sand or sea sand, Flugsand, or rock dust. Suitable sand can have a particle size of 150 μm to 2000 μm, preferably 200 μm to 2000 μm, particularly preferably 300 μm to 1800 μm.

［式中、Ｒ¹はＣ₁〜Ｃ₁₈であり、基Ｒ²は同じか又は異なり、かつ、Ｒ²は水素原子又は１〜６個の炭素原子、好ましくは１又は２個の炭素原子を有するアルキル基である］
のアルキル置換されたシランを有することができる。 According to the claimed method, a silanizing agent is accordingly used for the water-repellent finish of sand. Such silanizing agents have the general structure I

Wherein R ¹ is C ₁ -C ₁₈ , the groups R ² are the same or different and R ² is a hydrogen atom or 1-6 carbon atoms, preferably 1 or 2 carbon atoms. It is an alkyl group having]
Of alkyl-substituted silanes.

を有するものである。 Preferred examples are groups:

It is what has.

［式中、基Ｒ¹及びＲ³は相互に独立してＣ₁〜Ｃ₁₈−アルキルであり、これは１又は複数のヘテロ原子、例えばＮ、Ｏ、Ｆ、Ｃｌ、Ｐ又はＳを含むことができ、基Ｒ²は同じか又は異なり、かつＲ²は水素原子又は１〜６個の炭素原子、好ましくは１又は２個の炭素原子を有するアルキル基であり、かつ、ｎ＋ｍはオリゴマー化度を２〜５０、好ましくは２〜３０を有するものとして決定する］のオリゴマー状シロキサン又はシランオリゴマーを有することができる。この場合に、好ましくは、平均オリゴマー化度２〜５０、好ましくは２〜３０を有するオリゴマー混合物であり、その際、この平均モル質量は好ましくは３００〜１００００ｇ／Ｍｏｌである。この一般式ＩＩのシランオリゴマーは、この場合、線状、環状及び／又は分枝状単位として存在できる。 Such silanizing agents are further represented by an idealized general structure II.

In which the radicals R ¹ and R ³ are independently of each other C ₁ -C ₁₈ -alkyl, which contains one or more heteroatoms, for example N, O, F, Cl, P or S. The radicals 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, and n + m is the degree of oligomerization Is determined to have 2 to 50, preferably 2 to 30]. In this case, an oligomer mixture having an average degree of oligomerization of 2 to 50, preferably 2 to 30, is preferred, the average molar mass being preferably 300 to 10000 g / Mol. This silane oligomer of the general formula II can in this case be present as linear, cyclic and / or branched units.

を有するものである。 Preferred examples of silane oligomers are groups:

It is what has.

［式中、基Ｒ⁴は同じか又は異なり、かつ、水素原子又は１〜６個の炭素原子、好ましくは１又は２個の炭素原子を有するアルキル基であり、かつ、ｏは５〜５０００、好ましくは２０〜１０００を有するものとして重合度を記載する］のポリマー状シリコーンを有することもできる。好ましい例は、基Ｒ⁴＝Ｈ−、ＣＨ₃−、Ｃ₂Ｈ₅−を有するものである。 Finally, such silanizing agents are represented by the idealized general formula III

[Wherein the radicals R ⁴ are the same or different and are a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, preferably 1 or 2 carbon atoms, and o is 5 to 5000, Preferably, the degree of polymerization is described as having 20 to 1000]. Preferred examples are those having the group R ⁴ ═H—, CH ₃ —, C ₂ H ₅ —.

  This silanizing agent is used according to the invention as an aqueous emulsion or as an aqueous solution.

  The silanizing agent-emulsion used according to the invention has a silanizing agent content of 0.5 to 99.9 w%, preferably 1 to 99 w%, particularly preferably 2.5 to 99 w%, particularly particularly preferably 5 to 5 w. 80% by weight. Units in w% are based on the total mass of the formulation.

It may be preferred that the silanizing agent emulsion according to the invention additionally comprises at least one emulsifier as an aqueous emulsion, which is preferably an alkyl sulfate with C ₈ -C ₁₈ -alkyl, C ₈ -C ₁₈ - alkyl a has a hydrophobic group Chuu, and 1 to 40 ethylene oxide (EO) - or propylene oxide (PO) - alkyl having units - and alkaryl ether sulfates, C ₈ -C ₁₈ - Alkyl sulfonates with alkyl, alkaryl sulfonates with C ₈ -C ₁₈ -alkyl, and half esters of sulfosuccinic acid with monohydric alcohols with 5 to 15 carbon atoms or alkylphenols, Alkali- and ammonium salts; 8-20 carbon atoms alkyl-, aryl- A carboxylic acid in the alkaryl- or aralkyl group, an alkyl- and alkaryl phosphate having 8-20 carbon atoms in the organic group, an 8-20 carbon atom in the alkyl- or alkaryl group. And an alkyl ether or alkaryl ether phosphate having 1 to 40 EO units, 8 to 40 EO units, and a C _{8 to} C ₂₀ carbon atom in the alkyl or aryl group. alkyl polyglycol ethers and alkaryl polyglycol ethers having, ethylene oxide / propylene oxide having 8 to 40 amino EO- or PO- units (EO / PO) - block copolymers, C ₈ -C ₂₂ - alkyl amine having an alkyl group And ethylene oxide or propylene oxide addition products, linear or branched Saturated or unsaturated C ₈ -C ₂₄ - having an alkyl group, and 1-10 hexose - alkylpolyglycosides having or oligoglycoside radical having a pentose units, silicon-functional surfactants or these emulsifiers Is selected from a series of mixtures.

  The emulsifier content is preferably 0.01 to 5% by weight relative to the total weight of the emulsion in the composition used according to the invention.

  Furthermore, the silanizing agent-emulsion used according to the invention is at least one hydrolysis- or condensation catalyst from the following series: complex compounds such as halides, oxides, hydroxides, imides, alcoholates Amides, thiolates, carboxylates and / or combinations of these substituents of the Periodic Table of Elements (PSE) 3rd and 4th main groups and subgroups of PSE II, III, IV, V, VI, VII and Of the elements of VIIIa, VIIIb and VIIIc, in particular titanate or zirconate, for example tetra-n-butyl orthotitanate or tetra-n-propyl orthozirconate. Furthermore, oxides, hydroxides, hydrogen phosphates, hydrogen sulfates, sulfides, hydrogen sulfides, carbonates or hydrogen carbonates of the first and second main groups of PSE and / or alcoholates, preferably Sodium methanolate or sodium ethanolate and / or amino alcohols, preferably 2-aminoethanol or 2- (N, N-dimethyl) aminoethanol can be used.

  Finally, carboxylic acids such as formic acid, acetic acid or propionic acid and mineral acids such as hydrochloric acid or phosphoric acid can be used.

  Furthermore, the silanizing agent-emulsion used according to the present invention is preferably further supplemented with inorganic or organic acids, buffer substances, bactericides, bactericides, algicides, microbicides, odor substances, corrosion inhibitors, storage. Conventional aids selected from agents and rheology aids can be included.

  The silanizing agent-emulsion used according to the invention can preferably be further diluted with water before its use. In this case, all types of water are suitable in principle, for example deionized water, drinking water, waste water or sea water. The dilutions that can be used according to the invention are 1 part silanizing agent-emulsion and 0-99 parts water, preferably 1 part silanizing agent-emulsion and 0.1-49 parts water, particularly preferably 1 Part of silanizing agent-emulsion and 1 to 9 parts of water.

  In step (b) of the process according to the invention, the sand to be treated is first sieved in order to remove the coarse content having an average sand particle size> 2000 μm.

  The grain size of the sand can be distinguished by sand windsten, classification, sieving or a combination of these methods.

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

The concept of “internal surface area _sand ” is understood here and below as the quotient of the volume of sand used and the average volume of sand particles multiplied by 0.74 and the average surface area of the sand particles. Is done. The average volume and surface area of the sand particles are determined in the same manner as is known to those skilled in the art, assuming approximately spherical sand particles. Thereby, the internal surface area _sand can be calculated from the sand average particle size and bulk density of the sand and via the volume and surface area of the individual sand particles.

In step (d) of the method of the present invention, the sand obtained in step (c) is converted into a silanizing agent-emulsion and 0.19 · 10 ^{−2 to} 5.0 · 10 ⁻² (g silanizing agent). / (M ² internal surface area _sand ) in an amount of 500 pm to 4000 rpm and mixed for a period of 1 to 10 minutes.

In the method of the present invention, preferably 0.5 · 10 ^{−2 to} 3.5 · 10 ⁻² , particularly preferably 1.0 · 10 ^{−2 to} 3.0 · 10 ⁻² (g silanizing agent) / (m ² internal surface area _sand ) can be used.

  The sand to be treated is mixed in step (d) with a silanizing agent-emulsion in a suitable mixing device at a rotational speed of 500 rpm to 4000 rpm. This is mixed for a period of 1 to 10 minutes at this speed.

  As a mixing device, an internal mixer, such as a Loedige mixer, a corn mixer, a stirring tank, a kneader, a mixer (only examples are given) can be used. A suitable mixing device is preferably such that the sand particles do not break into smaller particles during this mixing process. Preferably, a mixing device should be selected in which the introduction of energy into the composition composed of sand and silanizing agent-emulsion does not cause chemical or physical conversion in the volume of sand particles.

  Furthermore, it is preferable to increase the rotational speed by 1.5 to 4 times after a period t1 of 1 to 10 minutes and maintain the rotational speed thus achieved for a period t2 of 0.5 to 120 minutes. be able to.

  Such an approach has the advantage that the silanizing agent-emulsion used according to the invention reacts completely with the sand or the surface of the sand particles, thereby increasing the hydrophobic persistence of the sand. .

  The sand obtained by step (d) is subsequently dried at a temperature of 30-90 ° C., preferably 40-80 ° C. for 0.5-2 h in step (e) of the process of the invention. In this case, this heat supply can also be realized by means of a furnace, a heat lamp or by sunlight irradiation.

In particular, the means for drying by solar radiation offer great advantages in substantial applications for energy savings, especially in desert areas.
Preferably, the sand obtained by step (d) is applied on a large area surface in order to subject this solar irradiation to as much as possible the amount of sand particles treated by steps (a) to (d) at the same time. Can be distributed.
With this option, the method according to the invention is particularly economical and is most economically feasible when both options are considered together.

  The advantage of the claimed method lies in the intimate mixing of the sand particles and silanizing agent with known required metering. This method of the present invention ensures that the sand is obtained with the amount of silanizing agent to be used with minimal water repellency.

  The subject of the invention is therefore likewise the hydrophobic sand obtained by the process of the invention.

  Similarly, the subject of the present invention is hydrophobic sand with reduced or no water penetration.

  Finally, the subject of the present invention is a useful-and / or ornamental plant irrigation as a means to prevent soil water evaporation in soil structure and in horticulture during landscape shaping, in erosion protection of soil layers It is also the use of the hydrophobic sand according to the invention in agriculture as a barrier against water penetration for.

  An advantage with respect to the use of the invention is that the hydrophobic sand treated and dried according to the invention is spread over all of the surfaces intended for this purpose and is easily dispersed to the same extent. It is also possible and may be useful in many cases to first remove one or more layers of the surface to be treated and then sew water repellent sand. Finally, it can also be preferred to re-cover the treated sand that has been sowed with one or more soil layers. In this way, preferably erosion of this treated sand by wind or water can be avoided.

  Below, the present invention will be described in detail based on examples.

Example 1:
Silica sand H 32 (CAS: 14808-60-7, average grain size: 0.32 mm, bulk density according to DIN EN 1097-3: 1.515 g / cm ³ ) ethoxy-substituted propylsiloxane in a Loedige mixer It was treated with a diluted aqueous emulsion (average molar mass 500-900 g / mol, siloxane content about 50%, hereinafter referred to as E).
For this purpose, 2.5 kg of silica sand was charged into the Loedige mixer.
This aqueous emulsion E was diluted with a ratio of 1 part E: 9 parts water, whereby a silanizing agent-emulsion was obtained. 6.6 ml of this diluted emulsion was subsequently added dropwise with a pipette. Mix at 1575 rpm for 10 minutes, then mix at 2800 rpm for 5 minutes. The silica sand thus treated was subsequently dried at 80 ° C. for 2 hours. Subsequently, the water settlement test described below was conducted.

Example 2:
As in Example 1, but the silanizing agent-emulsion was obtained by using E at a higher concentration (1 part E: 4 parts water). This hydrophobizing action was verified by a water subsidence test as described below.

Comparative example:
Fine sand (desert sand from Dubai, average grain size: 100 μm, bulk density: 1.541 g / cm ³ ) was treated with E in a Loedige mixer.
To this end, 1.5 kg of fine sand was charged into a Loedige mixer and 3.82 g of silanizing agent-emulsion (obtained by diluting 1 part E with 9 parts water) was added.
Mix for 10 minutes at 1575 rpm. The fine sand thus treated was subsequently dried at 80 ° C. for 2 hours.
This hydrophobizing action was verified by a water subsidence test as described below. Sand treated in this way is not hydrophobic in this context.

Example 3:
Performed as in the comparative example, but according to the invention, 200 g of fine sand was treated with 2.11 g of silanizing agent-emulsion (obtained from E diluted with 9 parts of water with 1 part of E) and subsequently A water settlement test was conducted.

Example 4:
According to the present invention, 1000 g of rough sand (desert sand from Dubai, average grain size: 500 μm, bulk density: 1.64 g / cm ³ ) was added to 2.48 g of silanizing agent according to the present invention. Treatment with an emulsion (obtained from E diluted with 9 parts of water with 1 part of E) followed by a water settlement test.

Water subsidence test Sand is filled into an aluminum cup at a height of about 1 cm, hardened and pressed by hand, and thus the sand has a horizontally extending surface. Next, two drops of distilled water are sprinkled on the surface with a pipette with a drop diameter of 5 mm. The water droplets have at least a droplet diameter interval. The test arrangement was left in an open system under ambient conditions (20 ° C., 1013 hPa) and the droplets were observed over a period of several hours. The period of time that elapses before both droplets each subsided completely in the sand was measured. From this period an arithmetic average value is formed, which is hereinafter referred to as residence time.

Table 1 below gives an overview of the results.

The results from Table 1 and Examples 1, 2, 3 and 4 lead to the conclusion that each particle size sand can be made water repellent with a silanizing agent-emulsion according to the present invention. To this end, according to the invention, 0.19 · 10 ^{−2 to} 3.0 · 10 ⁻² g of silanizing agent is used per 1 m ^{2 of} internal surface area _sand .

Claims (12)

Next step:
(A) a step of preparing sand;
(B) removing the coarse content having an average sand particle size> 2000 μm, and subsequently
(C) the step of measuring the bulk density of the sand obtained by step (b), the average particle size of the sand particles and the internal surface area _sand , and subsequently
(D) the sand obtained by step (c) together with the silanizing agent-emulsion in a mixing device,
0.19 · 10 ^{−2 to} 5.0 · 10 ⁻² (g silanizing agent) / (m ² internal surface area _sand )
At a rotational speed of 500 rpm to 4000 rpm,
Mixing for 1 to 10 minutes, and subsequently
(E) The manufacturing method of hydrophobic sand including the process of drying at the temperature of 30-90 degreeC for 0.5 to 2 hours.   The process according to claim 1, characterized in that in step (a) the sand is selected from quartz sand, river sand, sea sand, flying sand, rock dust or a mixture of these sands.   3. The method according to claim 1 or 2, characterized in that the grain size of the sand is brought to 150 [mu] m to 2000 [mu] m before the subsequent step (c) of step (b).   4. A method according to claim 3, characterized in that the grain size is distinguished by sand breezes, classification, sieving or a combination of these methods.   In step (d), a silanizing agent—an aqueous emulsion of a silane of structure I, an aqueous emulsion of a siloxane of structure II, an aqueous emulsion of a silicone of structure III, or a mixture of these emulsions is used as the silanizing agent in the emulsion. 5. A method according to any one of claims 1 to 4, characterized in that:   6. The method of claim 5, wherein the sand is mixed with the silanizing agent-emulsion in a mixing device selected from a Loedige mixer. In the step (d), first, mixing is carried out at the rotational speed D1 during the time 1 to t1, and subsequently at the rotational speed D2 during the time t2,
1 <t1 <10 minutes, and 0.5 <t2 <120 minutes, and 500 rpm ≦ D1 <D2 ≦ 4000 rpm
The method according to claim 5 or 6, wherein:   The method according to claim 1, wherein sunlight is used as a heat supply source in the step (a).   The method according to any one of claims 1 to 8, wherein in step (e), the sand obtained in step (d) is dispersed over a wide area surface.   Hydrophobic sand obtained by the method according to any one of claims 1 to 9.   Hydrophobic sand, characterized in that the water droplets subjected to the water settlement test have a residence time of at least 3 minutes on the horizontal sand surface.   Useful as soil water evaporation prevention means in soil structure, landscape modeling, horticulture, soil layer erosion protection, and / or as a prevention layer against water penetration for irrigation of ornamental plants Use of the hydrophobic sand according to any one of claims 1 to 11, in agriculture.