WO2022139497A1 - Method for modifying surface of inorganic particles through ball-milling step and inorganic particles modified by method - Google Patents

Abstract

Disclosed are a method for modifying the surface of inorganic particles and inorganic particles which are surface-modified by the method. The method for modifying the surface of inorganic particles comprises the steps of: preparing a mixture by mixing inorganic particles and a silicone polymer; and adding the mixture and ball-milling same so that the mass ratio of the mixture and a ball for milling is 1:5-1:20.

Description

Surface modification method of inorganic particles using ball milling process and inorganic particles modified by the method

The present invention relates to a method for modifying the surface of an inorganic particle and to an inorganic particle whose surface is modified by the method, and more particularly, to an inorganic particle, which is a metal oxide or a metal having an oxide film on the surface, of a silicone polymer having a siloxane backbone; It relates to a method of modifying the surface of the inorganic particles by ball milling after mixing, and the inorganic particles having a surface-modified surface by the method.

As a method for modifying the surface of an inorganic particle, a method of attaching or synthesizing an organic single molecule or a polymer to the surface of the particle has been used until now. In general, the surface of the inorganic material contains most functional groups, especially hydroxyl groups (-OH), and the surface of the inorganic material can be modified by reacting a single organic molecule or polymer having various functional groups capable of reacting with these functional groups with the inorganic oxide particles. have. In addition, in the process of synthesizing inorganic particles from a precursor, a method of attaching a desired organic molecule or polymer, or substituting a ligand with a desired organic molecule or polymer after pre-attaching a ligand can also be used for surface modification of inorganic materials. have. In addition to the surface modification method by direct bonding, a polymer having a functional group capable of cross-linking on the surface of the inorganic particle may be cross-linked and coated on the surface of the inorganic particle through a catalytic reaction to modify the surface. In addition to the method of attaching the polymer to the inorganic particles as in the above methods, the surface of the inorganic particles may be modified by first synthesizing a starting material on the surface of the inorganic particle and then polymerizing the starting material with a polymer.

However, all of the above-mentioned reforming methods are chemical reactions performed in an organic solvent, and the use of a large amount of organic solvent and chemicals is indispensable. In addition, since the surface of the inorganic particles is modified through a process spanning several steps, the complexity of the process is high and the energy required during the process is high. For the above reasons, the conventional method for modifying the surface of inorganic particles may cause many environmental problems, and it is not cost-effective to be used in industrial fields. Accordingly, there is an increasing need for a simple and economical method for surface modification of inorganic particles that can overcome the various disadvantages described above.

It is an object of the present invention to provide a method for surface modification of inorganic particles, in which inorganic particles and a silicone polymer are mixed and then ball milled.

Another object of the present invention is to provide a surface-modified inorganic particle modified by the surface modification method of the inorganic particle.

According to an embodiment of the present invention, a method for surface modification of inorganic particles includes preparing a mixture by mixing inorganic particles and a silicone polymer; and ball milling by inputting the mixture so that the mass ratio of the mixture and the milling ball is 1:5 to 1:20, wherein the inorganic particle is a metal oxide or a metal having an oxide film on the surface, The silicone polymer may be a polymer having a siloxane backbone.

In one embodiment, when the viscosity of the silicone polymer is 500 cSt or more, the step of mixing the silicone polymer with an organic solvent before ball milling may be further included.

In an embodiment, the organic solvent may be one selected from methanol, ethanol, acetone, hexane, and toluene.

In one embodiment, the ball milling step may be performed for 1 hour to 24 hours.

In one embodiment, the ball milling step may be performed at 25 ℃ to 100 ℃.

In one embodiment, after the ball milling step, the step of separating the particles using a centrifuge may be further included.

In one embodiment, the inorganic particles may include a mixture of two or more inorganic particles.

In one embodiment, the polymer having a siloxane skeleton may include a block or random copolymer having a siloxane skeleton.

According to an embodiment of the present invention, the surface-modified inorganic particles may be manufactured according to the method for surface-modifying the inorganic particles.

According to the present invention, since the surface of the inorganic particles is modified only by ball milling a mixture of inorganic particles and silicone polymer without using a catalyst or a specific functional group, the use of organic solvents is minimized and energy consumption is reduced to minimize the use of organic solvents. surface can be modified. In addition, since the process of modifying the surface of the inorganic particles is simplified to a single (one-step) process, it is effective to economically modify the surface of a large amount (kg scale or more) of the inorganic particles.

1 shows the structural formula of the silicone polymer used in the present invention.

2 shows a surface modification method of iron oxide particles according to Example 1 of the present invention.

3 shows a surface modification method of titanium dioxide particles according to Example 2 of the present invention.

4 shows a TEM image of the surface-modified iron oxide particles obtained in Example 1 of the present invention.

5 shows a TEM image of the surface-modified titanium dioxide particles obtained in Example 2 of the present invention.

6 is an X-ray photoelectron spectroscopy (X-ray Photoelectron Spectroscopy) measurement graph of the surface-modified iron oxide particles obtained in Example 1 of the present invention.

7 shows a Fourier Transform Infrared Spectroscopy (Fourier Transform Infrared Spectroscopy) measurement graph of the surface-modified titanium dioxide particles obtained in Example 2 of the present invention.

Hereinafter, embodiments of the present invention will be described in detail. Since the present invention can have various changes and can have various forms, specific embodiments are illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to the specific disclosed form, it should be understood to include all modifications, equivalents and substitutes included in the spirit and scope of the present invention.

Terms such as first, second, etc. may be used to describe various elements, but the elements should not be limited by the terms. The above terms are used only for the purpose of distinguishing one component from another.

Throughout the specification, when a part "includes" or "includes" a certain element, it means that other elements may be further included unless otherwise defined. Also, as used herein, the singular expression includes the plural expression unless the context clearly dictates otherwise.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs, and are clearly defined in this application. Unless defined, it is not to be construed in an idealistic or overly formal sense.

The method for surface modification of inorganic particles of the present invention comprises the steps of preparing a mixture by mixing inorganic particles and a silicone polymer; and ball milling by inputting the mixture so that the mass ratio of the mixture and the milling ball is 1:5 to 1:20, wherein the inorganic particle is a metal oxide or a metal having an oxide film on the surface, The silicone polymer may be a polymer having a siloxane backbone.

Ball milling is one of the grinding methods used to grind or mix materials. Ball milling is a process using impact and wear, and mixing and pulverization of materials occurs by impact when a milling ball in a rotating ball mill falls near the top.

The ball milling may be performed by a ball mill composed of a hollow cylindrical vessel rotating about an axis, and the axis of the vessel may be horizontal or nearly horizontal. The vessel is partly filled with milling balls, which become the grinding medium. The milling ball may be made of stainless steel, ceramic, or rubber. In addition, the inner surface of the container may generally be constructed of a wear-resistant material such as manganese steel or a rubber lining, preferably a rubber lining.

In the present invention, the ball milling process can mix and chemically combine inorganic particles and silicone polymer with a milling ball and a rotating container. In addition, the ball milling process can increase the surface area in contact with the silicone polymer by finely pulverizing the aggregated inorganic particles. When the contact surface area between the inorganic particles and the silicone polymer is increased, the adsorption reaction between the inorganic particles and the silicone polymer may be further activated.

In addition, the size of the inorganic particles can be adjusted through the pulverization process. The mass ratio of the mixture of the inorganic particles and the silicone polymer and the grinding ball may be 1:5 to 1:20, and may be selected according to a desired particle size.

In this case, the thermal energy generated during milling may promote the surface adsorption reaction of the silicon polymer to more effectively enable surface modification of the inorganic particles.

The inorganic particles may be SiO ₂ , TiO ₂ , SnO ₂ , and Al ₂ O ₃ , such as a metal oxide or any metal having an oxide film on the surface (aluminum, iron, copper, or stainless steel, etc.). . In addition, the inorganic particles may include a mixture of two or more inorganic particles.

The silicone polymer may be any polymer having siloxane as a backbone, and may include block and random copolymers having siloxane as a backbone.

The silicone polymer may exhibit a property capable of easily bonding with the oxide film of the inorganic particles by breaking the siloxane skeleton in the silicone polymer during the ball milling process. These chemical bonds are bonds that occur due to the inherent properties of silicone polymers, and do not require specific functional groups or catalysts for this purpose.

1 shows the structural formula of the silicone polymer used in the present invention.

1, R or R' of the silicone polymer may be substituted with a functional group to be applied to the surface of the inorganic particle. The functional group R of FIG. 1 may be substituted with -H, -CH ₃ , -CH ₂ CH ₃ , or -C ₆ H ₆ , and the functional group R' of FIG. 1 is, -H, -CH ₃ , -O -CH=CH ₂ , or -OH, etc. may be substituted. Since the functional group may be chemically bonded to the surface of the oxide film of the inorganic particle and the functional group may be bonded to the surface of the inorganic particle, the functional group may be surface-modified to variously control the properties of the inorganic particle.

When the viscosity of the silicone polymer is 500 cSt or more, the step of mixing the silicone polymer with an organic solvent before ball milling may be further included.

When the viscosity of the silicone polymer is high, since milling with the inorganic particles may not be performed smoothly, it is preferable to lower the viscosity of the silicone polymer by mixing it with an organic solvent.

Here, the organic solvent may be one selected from methanol, ethanol, acetone, hexane, and toluene.

The ball milling time may be adjusted according to the size of the desired particles, and preferably may be performed for 1 hour to 24 hours, and if desired, milling may be performed for 24 hours or more.

The ball milling step may be performed at 25 °C to 100 °C.

The inside of the ball mill vessel may be a general atmospheric condition, and various desired weather conditions may be selected. The gaseous conditions may be argon, nitrogen, or oxygen gaseous conditions.

In addition, as the gas pressure inside the ball mill container, normal pressure (1 atm), vacuum, or high pressure may be selectively used according to desired conditions.

After the ball milling step, the step of separating the particles using a centrifuge may be further included.

In addition to the centrifuge, a sedimentation method may be used to separate the particles.

The surface modification method of the inorganic particles of the present invention was carried out through the following specific process.

<Example>

Example 1: Surface modification of iron oxide particles

Example 1 relates to a method for modifying the surface of an iron oxide (Fe ₃ O ₄ ) particle, and the example is schematically illustrated in FIG. 2 of the present invention.

S1: Iron oxide particles and silicone oil (Polydimethylsiloxane, trimethylsiloxy terminated, viscosity: 100 cSt) were mixed in a mass ratio of 1:3. The mixture was put into a ball mill container so that the mass ratio of the mixture to the grinding balls was 1:5.

S2: The mixture was milled at room temperature (25° C.) and atmospheric pressure (1 atm) for 24 hours.

S3: Thereafter, the surface-modified iron oxide particles were dispersed in toluene and separated using a centrifuge.

Example 2: Surface modification of titanium dioxide particles

Example 2 relates to a method for modifying the surface of titanium dioxide (TiO ₂ ) particles, which embodiment is schematically illustrated in FIG. 3 of the present invention.

S1: Titanium dioxide particles and a silicone polymer (Methylhydrosiloxane-dimethylsiloxane copolymer, trimethylsiloxane terminated, viscosity: 25 to 35 cSt) were mixed in a mass ratio of 1:5. The mixture was put into a ball mill container so that the mass ratio of the mixture to the grinding balls was 1:10.

S2: The mixture was milled at 50° C. and atmospheric pressure (1 atm) for 12 hours.

S3: Thereafter, the surface-modified titanium dioxide particles were dispersed in toluene and separated using a centrifuge.

The surface-modified particles prepared in Examples 1 and 2 of the present invention were analyzed through the following experiments.

<Experimental example>

Experiment 1: TEM

The structures of the surface-modified inorganic particles obtained in Examples 1 and 2 of the present invention were observed with a transmission electron microscope (TEM).

Figure 4 shows a TEM image of the surface-modified iron oxide particles obtained in Example 1 of the present invention, Figure 5 shows a TEM image of the surface-modified titanium dioxide particles obtained in Example 2 of the present invention.

In both examples, it can be seen that the silicone polymer is bonded to the surface of the inorganic particles.

Experiment 2: X-ray photoelectron spectroscopy (XPS)

6 is an X-ray photoelectron spectroscopy (X-ray Photoelectron Spectroscopy) measurement graph of the surface-modified iron oxide particles obtained in Example 1 of the present invention.

In the iron oxide XPS spectrum before surface modification, peaks of Fe-O-Fe and Fe-O-H intensity exist, whereas in the graph of iron oxide O-1s XPS spectrum and iron oxide Si-2p XPS spectrum after surface modification, the Fe-O- In addition to Fe and Si-O-Si of the conventional silicon polymer, novel Fe-O-Si intensity peaks were observed. This shows that the iron oxide particles obtained in Example 1 of the present invention were surface-modified by reacting with a silicone polymer.

Experiment 3: Fourier Transform Infrared Spectroscopy (FT-IR)

7 shows a Fourier Transform Infrared Spectroscopy (Fourier Transform Infrared Spectroscopy) measurement graph of the surface-modified titanium dioxide particles obtained in Example 2 of the present invention.

Referring to the graph of FIG. 7, unlike the titanium dioxide FT-IR graph before surface modification, in the FT-IR graph of titanium dioxide surface-modified by a silicon polymer, CH ₃ , Si-O-Si, and Si- A downward peak for the C functional group was observed. This shows that the titanium dioxide particles obtained in Examples of the present invention were surface-modified by reacting with a silicone polymer.

Although the above has been described with reference to the preferred embodiment of the present invention, those skilled in the art can variously modify and change the present invention without departing from the spirit and scope of the present invention as set forth in the claims below. You will understand that you can.

Claims (9)

preparing a mixture by mixing inorganic particles and a silicone polymer; and Including; adding the mixture to the ball milling so that the mass ratio of the mixture and the milling ball is 1:5 to 1:20; The inorganic particle is a metal oxide or a metal having an oxide film on the surface, The silicone polymer is a polymer having a siloxane backbone, A method for surface modification of inorganic particles. The method of claim 1, When the viscosity of the silicone polymer is 500 cSt or more, further comprising the step of mixing the silicone polymer with an organic solvent before ball milling, A method for surface modification of inorganic particles. 3. The method of claim 2, The organic solvent is one selected from methanol, ethanol, acetone, hexane or toluene, A method for surface modification of inorganic particles. According to claim 1, The ball milling step is performed for 1 hour to 24 hours, A method for surface modification of inorganic particles. According to claim 1, The ball milling step is performed at 25 ℃ to 100 ℃ A method for surface modification of inorganic particles. According to claim 1, After the ball milling step, further comprising the step of separating the particles using a centrifuge, A method for surface modification of inorganic particles. According to claim 1, The inorganic particles include a mixture of two or more inorganic particles, A method for surface modification of inorganic particles. According to claim 1, The polymer having a siloxane backbone comprises a block or random copolymer having a siloxane backbone, A method for surface modification of inorganic particles. According to any one of claims 1 to 8, wherein any one of the surface modification method of the surface modification of the inorganic particles, the surface-modified inorganic particles.

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