KR102266619B1 - Hydrophobic silica particle and preparing method thereof - Google Patents

Abstract

The present invention relates to silica particles having a hydrophobic surface and a method for preparing hydrophobic silica particles. The method for producing hydrophobic silica particles according to the present invention includes irradiating the silica particles with an ion beam. According to the method of the present invention, after irradiation with the ion beam, the amount of H present in Si-O-H on the surface of the silica particle is reduced by 50% or more. Since the hydrophobic silica of the present invention exhibits semi-permanent hydrophobicization properties, the hydrophobic silica of the present invention can exhibit excellent effects in terms of product function improvement and quality deterioration improvement.

Description

Hydrophobic silica particles and their preparation method {Hydrophobic silica particle and preparing method thereof}

The present invention relates to silica particles having a hydrophobic surface and a method for producing hydrophobic silica particles. Specifically, the present invention relates to a technique for selectively removing surface Si-OH functional groups of silica particles and silica materials using an ion beam irradiation method.

Silica powder is an industrial raw material used in a variety of applications in various industries, for example, paints, coatings, plastic block inhibitors, fire extinguishing powders, and the like. For industrial mass production, silica powder is generally produced by chemical co-precipitation. This is because it is an important production process selected for mass production of powder particles and prevention of explosion safety accidents that may occur in the process of handling powder in the production process. _{Therefore, the surface of SiO 2} particles produced by chemical co-precipitation in aqueous solution inevitably leaves a hydroxyl group (-OH), which is a hydrophilic functional group, on the surface. Residual hydroxyl groups on the surface are removed through the treatment process.

_{The SiO 2} molecular sieve finally manufactured through heat treatment at the end of the process may come into contact with moisture in the air over time during transportation or storage after manufacturing, and thus has a property of being reduced back to a surface having a hydroxyl group.

Silica powder with these characteristics cannot be stored for more than a few days after being manufactured, and as the storage time elapses, the hydroxyl group reduction phenomenon caused by moisture in the air causes the hydrophilicity of the silica surface, making it difficult to store polymer products such as rubber and plastics. When used as a filler for reinforcing physical properties, it may lead to a fatal problem of poor dispersion in the product, which may cause a defect in the durability and function of the product.

In addition, the lack of long-term storability of the product adversely affects the securing of industrial economic feasibility related to production, distribution, and storage. In order to increase the industrial utilization of silica powder, it is urgently required to develop a new method of manufacturing technology to solve this problem.

The present invention is to provide a new dry treatment method for selectively removing hydroxyl groups from the surface _{of the prepared SiO 2 powder.} Through this, the surface-treated SiO ₂ can continuously maintain its hydrophobic surface properties for a long time, and it is advantageous for securing economic feasibility by securing the possibility of long-term storage, and it is also possible to increase the amount of use to strengthen the physical properties of the product, thereby enhancing the performance of the finished product may have advantages. Therefore, the present invention is _{to provide a SiO 2} powder and a method for preparing the same for inhibiting the generation of hydroxyl groups.

The present invention provides hydrophobic silica particles having a structure represented by Formula 1.

[Formula 1]

(HOSi) _1-x (Si=O) _x

In Formula 1, x has a value of 0.5 to 1.

In addition, the present invention provides a method for producing hydrophobic silica particles comprising the step of irradiating the silica particles with an ion beam.

Si=O silica from which Si—OH is removed of the present invention exhibits semi-permanent nonionic properties. When the silica treated with the ion beam of the present invention is used, an excellent effect can be exhibited in terms of product function improvement and quality degradation improvement.

In addition, by using the method for manufacturing nonionic silica particles of the present invention, it is possible to modify the silica surface properties without a separate organic chemical substance, thereby solving the problem of the generation of impurities due to component decomposition in the product and distribution process. In addition, the nonionic maintenance aging of the silica surface is greatly improved, and when used as a filler, it is possible to greatly improve the problem of quality deterioration due to phase separation of the product.

In addition, nonionic silica can greatly increase the shelf life of industrial silica, so it is easy to control the production process from the production and supplier side, and it is easy to mass production and storage, so economic profitability can be greatly improved, and the nonionic silica surface manufacturing process is simplified. Thus, the process time can be greatly reduced.

The following drawings attached to the present specification illustrate preferred embodiments of the present invention, and serve to further understand the technical spirit of the present invention together with the above-described content of the present invention, so the present invention is limited to the matters described in those drawings It should not be construed as being limited.
1 schematically illustrates the mechanism by which -OH groups on the surface according to the present invention are removed.
Figure 2 shows a graph of the FT-IR analysis results before irradiation (bare), Example 1 (N _{2 ) and Example 2 (Ar).}
Figure 3 shows a graph of the results of FE-SEM analysis before irradiation (bare), Example 1 (N _{2 ) and Example 2 (Ar).}
Figure 4 shows a graph showing the results of 1H-MAS-NMR analysis before irradiation (bare), Example 1 (N _{2 ) and Example 2 (Ar).}
Figure 5 shows a graph of the FT-IR analysis results before irradiation (bare), Example 3 (N _{2 ) and Example 4 (Ar).}
6 is a graph showing the results of FE-SEM analysis before irradiation (bare), Example 3 (N _{2 ) and Example 4 (Ar).}
7 is a graph showing the results of 1H-MAS-NMR analysis before irradiation (bare), Example 3 (N _{2 ) and Example 4 (Ar).}

In order to achieve the above object, the present invention utilizes a particle ion beam irradiation technique to selectively remove the -OH functional group, which is a surface polar functional group, to induce a chemical surface change represented by the following Equation 1. Provided are a method for producing a near silica powder and hydrophobic silica particles prepared using the same.

[Equation 1]

Equation 1 above briefly describes the mechanism of changing the polarity of the silica surface to a non-polar condition by changing the chemical structure of the Si-OH type, which is produced in the silica particles with the lapse of time by ion beam irradiation, into a semi-permanent Si=O type chemical structure. it has been shown

The present invention provides a method for preparing silica particles having hydrophobicity in the form of a non-ionic surface, including the step of irradiating an ion beam, and hydrophobic silica particles prepared using the same.

hydrophobic silica particles

The hydrophobic silica particles of the present invention have a structure represented by the formula (1).

[Formula 1]

(HOSi)1-x(Si=O)x

In Formula 1, x represents a rational number of 0.5 to 1, for example, a rational number of 0.6 to 1, a rational number of 0.7 to 1, a rational number of 0.8 to 1, a rational number of 0.9 to 1, and a rational number of 0.95 to 1.

In the specification of the present invention, Chemical Formula 1 represents functional groups constituting the hydrophobic silica particles according to the present invention, and the bonding relationship between the functional groups is not limited to Chemical Formula 1 above.

The particle diameter (D50) of the hydrophobic silica particles may be 20 to 100 μm, more specifically 25 to 80 μm, 30 to 70 μm, 40 to 60 μm, and in one embodiment, the particle diameter of the silica particles may be 40 μm. . When the particle diameter of the hydrophobic silica particles is within the above range, a homogeneous mixed solution can be prepared when mixing for various applications of the hydrophobic silica particles. For example, if the size of the hydrophobic silica particles is less than the above range, the particles agglomerate and uniform mixing is difficult. can be

The 'SiOH' unit is a functional group having excellent bonding ability to moisture by a hydroxyl group, and is a unit present on the surface of silica particles to impart hydrophilicity.

The 'Si=O' unit may be formed by modifying the 'SiOH' unit, and is a unit present on the surface of silica particles to impart non-polar hydrophobicity.

The hydrophobic silica particles of the present invention include a structure represented by the above formula (1) on the surface (outer) of the silica particles by ion beam irradiation on the silica particles. Specifically, by irradiating the ion beam, it is possible to impart hydrophobicity by causing a change in the surface structure inside and outside the depth through which the ion beam is transmitted. In the present invention, considering the intensity and dose of the irradiated ion beam, the ion beam may penetrate up to about 5 μm from the surface. Accordingly, more specifically, 95% or more, for example, 96% or more, 97% or more, 98% or more, 99% or more, or 100% of the structure represented by Formula 1 above is 10 μm deep from the outermost part of the silica particle. within, more preferably 3 to 8 μm, or 4 to 6 μm, such as 5 μm.

In Formula 1, x may have a value converging to 1 by ion beam irradiation, and when x has a value converging to 1, hydrophobicity imparting and hydrophobicity maintenance effects may be excellent.

Method for producing hydrophobic silica particles

The method for producing hydrophobic silica particles of the present invention includes irradiating the silica particles with an ion beam.

The irradiation of the ion beam may be performed using a known means such as an ion beam accelerator, and the irradiation means is not particularly limited.

In the method for producing hydrophobic silica particles according to the present invention, in order to minimize exposure of silica particles to air and to prevent undesirable changes in surface properties due to fine particles such as water molecules and dust in the air, ion beams in a vacuum state It is desirable to investigate More specifically, the irradiation of the ion beam ^{may be performed in a vacuum of 10 -5} torr or less, and more specifically, in a vacuum of 10 ^-10 to 10 ^-5 torr.

In the method of the present invention, the irradiation of the ion beam is irradiated with ion particles formed from one or more gases selected from the group consisting of electrons, hydrogen, helium, nitrogen, oxygen, air, neon, argon, krypton and N _{2 O} will do More specifically, by sequentially irradiating ion particles formed from argon, nitrogen, and a mixture thereof, or ion particles formed from argon or nitrogen, or by irradiating ion particles formed from nitrogen alone, hydrophobicity and hydrophobicity of the silica surface The holding property can be further improved.

The irradiation of the ion beam is 10 ¹⁴ pieces/cm ² or more of the ion particles as above, for example, 10 ¹⁶ pieces/cm ² or more, such as 10 ¹⁴ to 10 ²⁰ pieces/cm ² It is the surface hydrophobicity modification of the silica particles. aspect may be preferable.

In addition, the energy of the ion beam may be 20 to 300 keV, for example, 100 to 200 keV.

In addition, the irradiation time of the ion beam is not limited thereto as determined by the energy and / or the amount of irradiation, for example, 10 seconds to 100 minutes, 80 seconds to 60 minutes to maintain the economical efficiency of the process and the hydrophobicity of the silica particles. It may be preferable in terms of characteristics.

The method for producing the hydrophobic silica particles of the present invention further comprises the step of spreading the silica particles to a thickness of 0.1 to 10 mm, more specifically 0.5 mm, on a substrate before irradiation with an ion beam, to improve the uniformity of the surface modification of the silica particles. can be improved

In the method for producing hydrophobic silica particles according to the present invention, silica particles having a particle diameter (D50) of 20 to 100 μm, for example, silica particles having a particle size of 40 μm may be used. In particular, the method for producing hydrophobic silica particles according to the present invention can be applied to various fields because there is no change in the particle size before and after hydrophobization of the silica particles. For example, in the hydrophobic silica mixing process, after selecting the size of silica particles as needed, they are hydrophobized by the method according to the present invention so that the required particle size can be used as it is, considering the size of the silica particles after surface modification Thus, it is possible to solve the problem of complexity of the conventional process in which the size of silica particles before hydrophobization must be selected.

In the specification of the present invention, the phrase 'there is no change in the particle size before and after hydrophobization of the silica particles' means that the size change of the silica particles before and after irradiation with an ion beam is within 5%, for example, within 4%, 3 %, within 2%, within 1%, or within 0.1%.

The method for hydrophobizing the surface of silica particles according to the present invention modifies the chemical structure of the surface of the silica particles through irradiation with an ion beam as described above. More specifically, when the amount of H is measured using 1H-MAS-NMR analysis, after irradiation with the ion beam, the amount of H present in Si-OH on the surface of the silica particle is 50 to 100%, for example 50 % or more, 60% or more, 70% or more, 80% or more, 90% or more, or 100% or more.

And, the hydrophobicity of the hydrophobic silica particles prepared according to the present invention may be maintained for 3 months or more, specifically, the decrease in the amount of H present in Si-OH on the surface of the silica particles may be maintained for 3 months or more .

The method for producing hydrophobic silica particles according to the present invention is a hydrophilic surface generated due to the presence of protruding Si-OH in the Si-O-Si structure on the surface of the silica particle, again with a stable hydrophobicity such as a nonionic structure such as a Si=O structure. structure can be formed. Since this modification of the surface chemical structure is a reduced structure in the form of a covalent bond, it is stable even when exposed to room temperature or air, and may exhibit the effect of maintaining hydrophobicity, but the hydrophobicization mechanism of the present invention is not limited thereto.

1 schematically shows an example of the mechanism by which the surface -OH group of the present invention is reduced.

The modification of the chemical structure of the surface of the silica particles may be confirmed using a known means such as FT-IR, SEM-EDX, and 1H-solid NMR in addition to 1H-MAS-NMR. For example, for measuring a transmittance through the FT-IR, the surface at the surface hydrophobic before and after the 960 cm ^-1, decrease in Si-OH gujo from 3500cm ^-1 or more legs and, less than 3500 cm ^-1 region of the silica particles It can be seen that the -OH structure is reduced due to the decrease in moisture (H _{2 O).}

The silica particles whose surface is hydrophobically-modified by the above method have the above surface properties, have a hydrophobic property for a long time, and more preferably exhibit a property that hydrophobicity does not decrease with aging.

FIG. 2 shows a graph of FT-IR light transmittance measurement results in a ^{4000 cm -1} to 500 cm ^-1 region before and after surface treatment of silica particles as an embodiment of a method for producing hydrophobic silica particles according to the present invention. . However, the configurations shown in the embodiments and drawings described in the present specification are merely the most preferred embodiment of the present invention and do not represent all the technical spirit of the present invention, so they can be substituted at the time of the present application It should be understood that various equivalents and modifications may be made.

Examples 1 and 2

_{SiO 2 particles having a particle diameter (D 50} ) of 40 μm were thinly spread to a thickness of 0.5 mm on a rectangular flat (10x5 cm) alumina boat-type sample irradiation tray, and then nitrogen was introduced into an ion beam irradiation apparatus. The injected sample was ^{created in a vacuum state of 10 -7} torr or less and irradiated with a nitrogen ion beam from a vertical beam irradiation device. The irradiated ion beam was 10 keV energy, and the irradiated ion water was irradiated ^{for 80 seconds with 10 17} pieces/cm ² vertical ion gun (Example 1).

In addition, hydrophobic silica particles were prepared in the same manner as in Example 1 except for irradiation with an argon ion beam (Example 2).

After the irradiation was completed, each sample was recovered after cooling in the atmosphere, and the presence or absence of a decrease in the hydrophilic -OH functional group of the sample and the extent thereof were confirmed through FT-IR, SEM-EDX, and 1H-MAS-NMR instruments (Fig. 2-4). ).

As can be seen in FIG. 2 , a decrease in the Si-OH structure in the ^{960 cm -1} and 3500 cm ^-1 sections and a decrease in the -OH structure in water in the ^{3100 cm -1 section were confirmed.}

In addition, as can be seen in FIG. 3 , it was confirmed that the external shape of the particles did not change even when the heat generated during beam irradiation did not occur. As can be seen in FIG. 4 , Si- through 1H-MAS-NMR analysis It was confirmed that the amount of H present in OH was reduced by 60% by ion beam irradiation.

Examples 3 and 4

_{SiO 2 particles having a particle diameter (D 50} ) of 40 μm to a thickness of 0.5 mm in a 2 cm diameter circular specimen fixing device were pressed thinly by hand, and then nitrogen was added to the ion beam irradiation device. The injected sample was irradiated with a nitrogen ion beam from a horizontal beam irradiation device in a vacuum ^{of 10 -7 torr or less.} The irradiated ion beam was 100 keV energy, and 10 ¹⁷ ions/cm ² irradiated ion water was irradiated for 1 hour in a vertical ion gun (Example 3).

In addition, hydrophobic silica particles were prepared in the same manner as in Example 3 except for irradiation with an argon ion beam (Example 4).

After the irradiation was completed, each sample was recovered after cooling in the atmosphere, and the presence or absence of a decrease in the hydrophilic -OH functional group of the sample and the extent thereof were confirmed through FT-IR, SEM-EDX, and 1H-MAS-NMR instruments (Figs. 5-7). ).

As can be seen in FIG. 5 , a decrease in the Si-OH structure in the ^{960 cm -1} and 3500 cm ^-1 sections and a decrease in the -OH structure in water in the ^{3100 cm -1 section were confirmed.}

In addition, as can be seen in FIG. 6 , it was confirmed that the external shape of the particles did not change even when the heat generated during beam irradiation did not occur. As can be seen in FIG. 7 , Si- through 1H-MAS-NMR analysis It was confirmed that the amount of H present in OH was reduced by 60% by ion beam irradiation.

Claims (16)

Hydrophobic silica particles having a structure represented by the formula (1).
[Formula 1]
(HOSi) _1-x (Si=O) _x
In Formula 1,
x has a value of 0.5 to 1.
The method according to claim 1,
Hydrophobic silica particles having a particle diameter (D50) of 20 to 100 μm.
The method according to claim 1,
The hydrophobic silica particle is a hydrophobic silica particle having a structure represented by the formula (1) on its surface.
4. The method according to claim 3,
More than 95 mol% of the structure represented by Formula 1 is hydrophobic silica particles that are present within 10 μm depth from the outermost shell of the silica particles.
Comprising the step of irradiating an ion beam to the silica particles,
The energy of the ion beam is 20 to 300 keV,
The method for producing hydrophobic silica particles, wherein the irradiation of the ion beam is to irradiate ion particles formed from one or more gases selected from the group consisting of hydrogen, nitrogen, argon and krypton.
6. The method of claim 5,
Irradiation of the ion beam is a method for producing a hydrophobic silica particle that is performed in a vacuum ^{of 10 -5 torr or less.}
delete delete delete 6. The method of claim 5,
The irradiation of the ion beam is 10 ¹⁴ to 10 ²⁰ pieces / cm ² Method of producing hydrophobic silica particles to irradiate the ion particles.
6. The method of claim 5,
The method for producing hydrophobic silica particles, wherein the irradiation of the ion beam is irradiated for 10 seconds to 100 minutes.
6. The method of claim 5,
The method of manufacturing hydrophobic silica particles further comprising the step of spreading the silica particles to a thickness of 0.1 to 10 mm on the substrate before irradiation with the ion beam.
6. The method of claim 5,
The particle diameter (D ₅₀ ) of the silica particles is a method for producing a hydrophobic silica particle of 20 to 100 μm.
6. The method of claim 5,
After irradiation with the ion beam, the amount of H present in the Si-OH on the surface of the silica particles is 50 to 100 mol% of the method for producing hydrophobic silica particles.
6. The method of claim 5,
A method for producing hydrophobic silica particles wherein the hydrophobicity of the prepared hydrophobic silica particles is maintained for at least 3 months.
The hydrophobic silica particles prepared according to the method of any one of claims 5, 6, 10 to 15.

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