Method for producing a polyurethane-silicon dioxide composite film

Abstract

A method for producing a polyurethane-silicon dioxide composite film, comprising the steps of: (a) Production of polystyrene particles; (b) Production of silicon dioxide polystyrene particles by mixing the polystyrene particles with silicon dioxide nanoparticles; (c) Producing amphiphilic silicon dioxide nanoparticles by subjecting the silicon dioxide polystyrene particles to a first surface treatment, removing the polystyrene particles and then subjecting the remaining silicon dioxide nanoparticles to a second surface treatment, (d) Producing a coating composition by mixing the amphiphilic silicon dioxide nanoparticles with polyurethane; and (e) Applying the coating composition to a surface of a substrate to form a coating layer and hardening the coating layer, the procedure further includes in step (a): Producing a styrene-fluid mixture by introducing a styrene monomer and a solvent into a reactor and stirring under a nitrogen atmosphere for a predetermined time; and Heating the styrene-fluid mixture to a temperature of 60 °C to 70 °C and Addition of an initiator to the reactor and reaction of the styrene-fluid mixture with the initiator, wherein the initiator comprises 2,2'-Azobis(2-methylpropionamidine)dihydrochloride.

Description

TECHNICAL AREA OF INVENTION

[0001] The present invention relates to a method for producing a polyurethane-silicon dioxide composite film with improved anti-fingerprint properties. BACKGROUND OF THE INVENTION

[0002] Contamination (e.g., soiling) with fingerprints can lead to user inconvenience by reducing the visibility of displays and touchscreens. With the development of automotive technology, not only vehicle instrument panels and central information displays, but also control panels such as navigation panels, radio panels, climate control panels, and the like have been replaced by displays and touchscreens. Consequently, there has been an increasing need to impart anti-fingerprint and anti-contamination properties (e.g., anti-soiling properties) to various high-gloss treated surfaces. Therefore, areas with a high probability of fingerprint contamination (e.g., soiling) have expanded, and the need for anti-fingerprint surface treatment technologies for motor vehicles has increased.

[0003] Components that leave fingerprints include sweat, sebum, dust, and the like. To prevent fingerprints on the surface of displays or similar devices, current methods primarily focus on improving contact angle properties against contamination, employing inorganic nanoparticles or coatings with fluorine compounds.

[0004] However, in the related technology, no continuous performance evaluation of the effectiveness of the anti-fingerprint surface treatment has been carried out, and commercialization cannot be realized due to the complexity of the surface treatment processes.

[0005] In related fields, investigations have been conducted into the application of acrylic resins, fluorine-based resins, or surface structures for the anti-fingerprint surface treatment of sheet steel or display surfaces. For example, a method for improving anti-fingerprint properties by applying a fluorine-based polymer to a surface has been proposed. However, this method can be disadvantageous because the polymer is only applied to the surface, and its anti-contamination properties (e.g., as an anti-soiling agent) are easily lost (e.g., easily worn away from the surface), thus reducing the anti-soiling resistance.Furthermore, methods have been proposed for creating an uneven surface structure using a mixture of a UV-curing resin and inorganic oxide nanoparticles, or for producing an anti-fingerprint film with a porous surface structure by forming / removing fine metal particles. However, due to the complexity of controlling the surface structure, these methods in related technologies can have many limitations regarding effective (e.g., efficient) productivity.

[0006] Furthermore, patents have been reported relating to an anti-fingerprint treatment of a specific substrate using an acrylic resin or a (specific) surface structure. For example, a method for the electroplating of a substrate surface with zinc, chromium, or the like, or on materials with improved anti-fingerprint properties, including a resin containing fluorine and a resin that is photopolymerizable, has been proposed. However, studies on anti-fingerprint surfaces with uneven surface structures are still insufficient.

[0007] From CN 1 06 587 075 A, a coating composition suitable as a polyurethane-silicon dioxide composite film and a process for its production are known, wherein the coating composition comprises polyurethane and amphiphilic silicon dioxide nanoparticles with a functional amine group and a functional fluorine group. Further coating compositions and processes for their production are known from CN 107 399 740 A and DE 10 2009 040 868 A1. From EP 3 066 164 B1, another coating composition and a process for its production are known, wherein polystyrene particles are mixed with silicon dioxide nanoparticles. EXPLANATION OF THE INVENTION

[0008] The object of the invention is to provide a method which includes simplified processes and in which, through the use of amphiphilic silicon dioxide nanoparticles, phase separation occurring in a polyurethane film can be prevented, so that anti-fingerprint properties can be imparted and improved and an uneven structure can be provided on the film surface.

[0009] This problem is solved by a method for producing a polyurethane-silicon dioxide composite film according to claim 1. Further developments are the subject of the dependent claims.

[0010] The term "amphiphilic" or "amphiphilicity," as used herein, refers to a material property that exhibits both hydrophobicity and hydrophilicity. For example, amphiphilic silicon dioxide nanoparticles may have both hydrophobic and hydrophilic groups on their surfaces or within the particles themselves, or be modified to do so. Examples of hydrophobic groups include saturated or unsaturated hydrocarbons such as alkyl, alkenyl, or aryl groups. Examples of hydrophilic groups include hydroxyl, amine, carboxyl, thiol, sulfonyl, carbonyl, acetyl, or phosphate groups.

[0011] The term "nanoparticle," as used herein, refers to a particle or particulate material with a size of approximately 1 nm to 999 nm, approximately 1 nm to 900 nm, approximately 1 nm to 800 nm, approximately 1 nm to 700 nm, approximately 1 nm to 600 nm, approximately 1 nm to 500 nm, approximately 1 nm to 400 nm, approximately 1 nm to 300 nm, approximately 1 nm to 200 nm, or approximately 1 nm to 100 nm. The size can be measured by a diameter, which can be the longest length along the two distal points (e.g., distal ends) of the particle.

[0012] To explain the invention, an illustrative coating composition based on polyurethane-silicon dioxide composite, which can be produced by the method and is heat-curable, or a coating composition with improved anti-fingerprint properties, is also explained, the explanation of which serves to improve the understanding of the method according to the invention.

[0013] The term “curing” or “hardening,” as used herein, refers to a process for curing or solidifying a polymeric resin, for example, starting from a mixture of one or more monomers and a curing agent (e.g., curing agent, e.g., initiator). Curing can be carried out by applying heat and / or UV light or by using chemical compounds. In certain embodiments, the illustrative coating composition can be cured by applying heat or increasing a temperature.

[0014] The illustrative coating composition can contain polyurethane with partially fluorinated, surface-treated silicon dioxide nanoparticles to provide anti-fingerprint properties. This illustrative coating composition can be used and applied to vehicle interior displays (e.g., vehicle interior displays) and interior surfaces to provide anti-fingerprint properties. Furthermore, for the purpose of better understanding the process according to the invention, an illustrative polyurethane-silicon dioxide composite film with enhanced anti-fingerprint properties is described, which has a non-uniform surface structure obtained using surface-treated, amphiphilic silicon dioxide nanoparticles.In particular, the phase separation of a polyurethane-silicon dioxide nanoparticle composite, which occurs during the curing of the coating composition under heat, can be controlled. A method according to the invention for producing the composite film is provided.

[0015] According to the invention, a method for producing a polyurethane-silicon dioxide composite film with improved anti-fingerprint properties is provided. The method comprises the following steps: (a) producing polystyrene particles; (b) producing silicon dioxide-polystyrene particles by mixing the polystyrene particles with silicon dioxide nanoparticles; (c) producing amphiphilic silicon dioxide nanoparticles by subjecting (e.g.,(d) subjecting the silicon dioxide polystyrene particles to a first surface treatment, removing the polystyrene particles, and then subjecting the remaining silicon dioxide nanoparticles to a second surface treatment, (d) producing a coating composition by mixing the amphiphilic silicon dioxide nanoparticles with polyurethane; and (e) applying the coating composition to the surface of a substrate to form a coating layer and curing the coating layer, thereby producing the polyurethane-silicon dioxide composite film.

[0016] In step (a) the process further comprises the following steps: preparing a styrene-fluid mixture by introducing a styrene monomer and a solvent into a reactor and stirring under a nitrogen atmosphere for a predetermined time; and heating the styrene-fluid mixture to a predetermined temperature and adding an initiator to the reactor and reacting the styrene-fluid mixture with the initiator.

[0017] Preferably, the solvent may suitably contain one or more solvents selected from the group consisting of water, ethanol, methanol, ethyl acetate, chloroform, and hexane. For example, the solvent may contain water or ethanol.

[0018] The styrene-fluid mixture may further contain a surfactant or a stabilizer. Preferably, the styrene-fluid mixture can be prepared by stirring.

[0019] The styrene-fluid mixture is heated to a temperature of approximately 60 °C to approximately 70 °C.

[0020] The initiator suitably contains 2,2'-azobis(2-methylpropionamidine) dihydrochloride. Preferably, the initiator can be 2,2'-azobis(2-methylpropionamidine) dihydrochloride.

[0021] The process may further include in step (b) the production of the silicon dioxide polystyrene particles by mixing and stirring a polystyrene solution containing polystyrene particles and a first silicon dioxide solution containing silicon dioxide nanoparticles in a volume ratio of 1:1 for a predetermined time.

[0022] The process may further include, in step (b), the addition of sodium chloride at a concentration of about 0.1 mmol / L to about 10.0 mmol / L to the mixture of the polystyrene solution and the first silicon dioxide solution. Step (b) of the process may include stirring the mixture and the sodium chloride.

[0023] The process may further include in step (c) the following steps: subjecting the silicon dioxide-polystyrene particles to a first surface treatment by adding the silicon dioxide-polystyrene particles either to i) a first compound containing a carboxyl group and an amine group or to ii) a second compound containing a carboxyl group and an amine group and stirring the same; adding the silicon dioxide-polystyrene particles to tetrahydrofuran after the first surface treatment and removing the polystyrene particles; and subjecting the silicon dioxide particles remaining after the removal of the polystyrene particles following the first surface treatment to a second surface treatment by adding the silicon dioxide particles to a compound and stirring the silicon dioxide particles and the compound. The compound may contain the first compound or the second compound that was not used in the first surface treatment.

[0024] The first compound can suitably contain N-(tert-butoxycarbonyl)-β-alanine. The first compound can be N-(tert-butoxycarbonyl)-β-alanine.

[0025] The second compound may contain perfluorooctanoic acid in a suitable manner. The second compound may be perfluorooctanoic acid.

[0026] The process may further include in step (d) the following steps: preparing a second silicon dioxide solution by dispersing the amphiphilic silicon dioxide nanoparticles in tetrahydrofuran; preparing a polyurethane solution containing polyurethane and a curing agent; and preparing the coating composition by mixing the polyurethane solution with the second silicon dioxide solution.

[0027] Preferably, the coating composition produced by the method according to the invention can contain the silicon dioxide nanoparticles in an amount of about 0.3 wt.% to about 10.7 wt.%, based on the total weight of the composition.

[0028] In step (e) the coating layer can be cured at a temperature of about 60 °C to about 90 °C.

[0029] Other aspects of the invention are disclosed below. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 shows an exemplary method for producing a polyurethane-silicon dioxide composite film according to an exemplary embodiment of the present invention. Fig. Figures 2A-2D show scanning electron microscope (SEM) images of exemplary polystyrene particles produced according to an exemplary embodiment of the present invention. Fig.Figures 3A-3D show scanning electron microscope (SEM) images of exemplary silicon dioxide nanoparticles produced according to an exemplary embodiment. Fig. Figures 4A-4D show exemplary silicon dioxide polystyrene particles produced according to an exemplary embodiment of the present invention. Fig. Figures 5A-5F show scanning electron microscope (SEM) images of exemplary silicon dioxide polystyrene particles produced under different stirring conditions in one step of the production of silicon dioxide polystyrene particles according to an exemplary embodiment of the present invention. Fig.Figures 6A-6G show scanning electron microscope (SEM) images of exemplary silicon dioxide polystyrene particles produced using different size ratios of polystyrene particles to silicon dioxide nanoparticles in a step of the production of silicon dioxide polystyrene particles according to an exemplary embodiment of the present invention. Fig. Figures 7A-7H show scanning electron microscope (SEM) images of exemplary silicon dioxide polystyrene particles produced using different concentrations of aqueous sodium chloride (NaCl) solution in a step of the production of silicon dioxide polystyrene particles according to an exemplary embodiment of the present invention. Fig. Figure 8 shows an exemplary method for the production of amphiphilic silicon dioxide nanoparticles according to an exemplary embodiment of the present invention. Fig.Figure 9 shows an exemplary method for the production of amphiphilic silicon dioxide nanoparticles according to an exemplary embodiment of the present invention. Fig. Figure 10 shows different types (e.g. types) of amphiphilic silicon dioxide nanoparticles produced according to an exemplary embodiment of the present invention. Fig. Figures 11A-11D show scanning electron microscope (SEM) images of exemplary particles produced by the first and second surface treatment processes in a step of the production of amphiphilic silicon dioxide nanoparticles according to an exemplary embodiment of the present invention. Fig.Figures 12A-12F show the test results of exemplary silicon dioxide nanoparticle emulsions before and after the surface treatment processes in a step of the production of amphiphilic silicon dioxide nanoparticles according to an exemplary embodiment of the present invention. Fig. Figure 13 shows an exemplary method for an exemplary polyurethane-silicon dioxide composite film by rod coating (e.g. rod coating) according to an exemplary embodiment of the present invention. Fig. Figures 14A-14E and 15A-15B show the measurement results of the transmittance of exemplary polyurethane-silicon dioxide composite films produced according to an exemplary method of the present invention. Fig. Figure 16 shows the measurement results of contact angles of exemplary polyurethane-silicon dioxide composite films produced according to an exemplary method of the present invention. Fig. 17A, Fig. 17B, Fig. 18A and Fig. Figure 18B shows atomic force microscope (AFM) images of exemplary polyurethane-silicon dioxide composite film surfaces produced according to an exemplary method of the present invention. Fig. Figure 19 shows a phase separation of exemplary amphiphilic silicon dioxide nanoparticles in a step of the production of a polyurethane-silicon dioxide composite film according to an exemplary embodiment of the present invention. Fig. Figures 20A-20C show contact angle properties of various types (e.g. types) of exemplary amphiphilic silicon dioxide nanoparticles and various curing processes produced according to an exemplary process of the present invention. Fig.Figures 21A-21B show atomic force microscope (AFM) images of exemplary polyurethane-silicon dioxide composite films produced according to an exemplary method of the present invention. Fig. Figures 22A-22F show scanning electron microscope (SEM) images of sections (e.g., cuts, e.g., areas) of exemplary polyurethane-silicon dioxide composite films produced according to an exemplary method of the present invention. Fig. Figures 23A-23G show transmission electron microscope (TEM) images of sections (e.g., cuts, e.g., areas) of exemplary polyurethane-silicon dioxide composite films produced according to an exemplary method of the present invention. Fig.Figures 24A-24E show energy-dispersive X-ray spectroscopy (EDS) images of sections (e.g., cuts, e.g., areas) of exemplary polyurethane-silicon dioxide composite films produced according to an exemplary method of the present invention. DETAILED DESCRIPTION

[0030] The terminology used herein serves solely to describe specific embodiments and is not intended to limit the invention. The singular forms "a," "an," "a," and "the," "a," and "the," as used herein, are intended to include the plural forms unless the context clearly indicates otherwise. Furthermore, it should be understood that the terms "have" and / or "having," "contain" and / or "containing," and "have," when used in this description, specify the presence of the aforementioned features, integers, steps, processes, elements, and / or components (e.g., parts) thereof, but do not exclude the presence or addition of one or more further features, integers, steps, processes, elements, components (e.g., parts), and / or combinations thereof.

[0031] It should be understood that terms such as "vehicle" or "vehicle-..." or any similar term used herein include motor vehicles in general, such as passenger cars, including so-called sport utility vehicles (SUVs), buses, trucks, numerous commercial vehicles, as well as, for example, watercraft, including a variety of boats and ships, and also, for example, aircraft and the like, and furthermore, hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles, and other vehicles powered by alternative fuels (e.g., fuels produced from resources other than petroleum). A so-called hybrid vehicle, to which reference is made here, is a vehicle that has two or more energy sources, for example, vehicles that are powered by both gasoline and electricity.

[0032] Unless otherwise stated or evident from the context, the term "approximately" (e.g., "about") used herein is to be understood as being within a normal tolerance in engineering, e.g., within two standard deviations of the mean. "About" (e.g., "about") may be understood as being within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the stated value. Unless otherwise clear from the context, all numerical values ​​provided herein are modified by the term "approximately".

[0033] Unless otherwise defined, the terms used herein (including technical and scientific terms) have the same meanings as they are generally understood by a person skilled in the art in which this invention / disclosure relates. Terms such as those commonly used and found in dictionaries should be interpreted as having meanings consistent with their context-dependent meanings in the technical field. Unless specifically defined, the terms used in this description are not to be interpreted as exhaustive or excessively formal.

[0034] The present invention is described in more detail below with reference to the accompanying drawings, in which exemplary embodiments of the present invention, i.e., exemplary embodiments of a method for producing a polyurethane-silicon dioxide composite film, are shown, and illustrative coating compositions and illustrative polyurethane-silicon dioxide composite films are further explained for a better understanding of the method according to the invention.

[0035] However, as will be clear to those skilled in the art, the described embodiments can be modified in numerous different ways without each modification deviating from the scope of the present invention as defined by the appended claims. Therefore, the scope of the present invention is not limited to the embodiments disclosed herein.

[0036] The process for producing the polyurethane-silicon dioxide composite film can generally include the following steps: producing amphiphilic silicon dioxide nanoparticles; producing a heat-curable coating composition based on polyurethane-silicon dioxide composite (the “coating composition”) by mixing the produced amphiphilic silicon dioxide nanoparticles with polyurethane in a predetermined ratio; and applying the produced heat-curable coating composition based on polyurethane-silicon dioxide composite and subsequently curing the composition, thereby producing the polyurethane-silicon dioxide composite film.

[0037] Fig. Figure 1 is a flowchart schematically illustrating an exemplary process for producing a polyurethane-silicon dioxide composite film according to an exemplary embodiment of the present invention. As shown in Fig.As shown in Figure 1, the process comprises the following steps: (a) producing polystyrene particles (S100); (b) producing silicon dioxide polystyrene particles (S200); (c) producing amphiphilic silicon dioxide nanoparticles (S300); (d) producing a heat-curable coating composition based on polyurethane-silicon dioxide composite (S400); and (e) applying the heat-curable coating composition based on polyurethane-silicon dioxide composite and then curing the applied composition, thereby producing the polyurethane-silicon dioxide composite film (S500).

[0038] Preferably, in step (a), producing polystyrene particles (S100), polystyrene particles can be produced by emulsion polymerization or dispersion polymerization. For example, a styrene monomer and a solvent can be placed in a reactor and stirred under a nitrogen atmosphere for a predetermined time, producing a styrene-fluid mixture. The produced styrene-fluid mixture can then be heated to a predetermined temperature, and an initiator can then be added and reacted, producing positively charged polystyrene particles.

[0039] The process for producing polystyrene particles by emulsion polymerization may include the following steps: introducing styrene monomer and water into a reactor, followed by stirring under a nitrogen atmosphere for a predetermined time, thereby producing a styrene-fluid mixture; and heating the produced styrene-fluid mixture to a predetermined temperature and then adding an initiator and reacting it with the heated styrene-fluid mixture, thereby producing polystyrene particles.

[0040] The process can include the production of polystyrene particles by dispersion polymerization and further the following steps: introducing a styrene monomer, ethanol, and a stabilizer into a reactor, followed by stirring under a nitrogen atmosphere for a predetermined time, thereby producing a styrene-fluid mixture; and heating the produced styrene-fluid mixture to a predetermined temperature and then adding an initiator to the reactor and reacting it with the heated styrene-fluid mixture, thereby producing polystyrene particles.

[0041] According to various exemplary embodiments of the invention, polystyrene particles can be produced as shown below. Example 1

[0042] In an exemplary embodiment, polystyrene particles can be produced by emulsion polymerization. For example, 20 mL of a styrene monomer and 200 mL of distilled water are added to a 500 mL reactor and then stirred uniformly under a nitrogen atmosphere at a speed of approximately 290 rpm. After stirring for about 30 minutes, the reaction solution is heated to a reaction temperature of 70°C, and 0.2 g of 2,2'-azobis(2-methylpropionamidine) dihydrochloride (AIBA) is added to the reactor as an initiator and allowed to react for 12 hours or longer. After completion of the reaction, the remaining unreacted material is removed by centrifugation for about 1 hour at approximately 3000 to 4000 rpm, producing polystyrene particles with a final particle size (e.g., final grain size) of approximately 490 nm. Example 2

[0043] In another exemplary embodiment, polystyrene particles can be produced in the same way as in Example 1, except that the stirring speed of the styrene monomer and the distilled water is changed to about 600 rpm, thereby producing styrene particles with a final particle size (e.g., final grain size) of 200 nm. Example 3

[0044] In another exemplary embodiment, polystyrene particles can be produced in the same way as in Example 1, except that the reaction temperature is changed to 60 °C, thereby producing polystyrene particles with a final particle size (e.g., final grain size) of 580 nm. Example 4

[0045] In an exemplary embodiment, 24 mL of a styrene monomer, 100 mL of distilled water, and 0.12 g of hexadecyltrimethylammonium bromide (CTAB) as a surfactant are added to a 250 mL reactor and then stirred uniformly at a speed of 600 rpm in a nitrogen atmosphere. After approximately 30 minutes of stirring, the reaction solution is heated to a reaction temperature of 70°C, and 0.2 g of 2,2'-azobis(2-methylpropionamidine) dihydrochloride (AIBA) is added to the reactor as an initiator and allowed to react for 12 hours or longer. After completion of the reaction, the remaining unreacted material is removed by centrifugation for approximately 1 hour at 3000 to 4000 rpm, producing polystyrene particles with a final particle size (e.g., final grain size) of approximately 90 nm. Example 5

[0046] In an exemplary embodiment, 20 mL of a styrene monomer, 200 mL of ethanol, and 2.0 g of polyvinylpyrrolidone (PVP; molecular weight: 10,000 g / mol) as a stabilizer are added to a 500 mL reactor and then stirred uniformly under a nitrogen atmosphere at a speed of 160 rpm. After approximately 30 minutes of stirring, the reaction solution is heated to a reaction temperature of 70°C, and 0.2 g of 2,2'-azobis(2-methylpropionamidine) dihydrochloride (AIBA) is added to the reactor as an initiator and allowed to react for 12 hours or longer. After completion of the reaction, the remaining unreacted material is removed by centrifugation for approximately 1 hour at 2,000 rpm, yielding polystyrene particles with a final particle size (e.g., final grain size) of approximately 1,300 nm.

[0047] Fig.Figures 2A-2D show scanning electron microscope (SEM) images of the exemplary polystyrene particles produced according to the examples of the present invention.

[0048] As in Fig. As shown in Figure 2A, the particle size of the polystyrene particles produced using the surfactant CTAB according to Example 4 was approximately 90 nm and, as shown in Fig. As shown in 2B, the particle size of the polystyrene particles produced according to Example 2 was approximately 200 nm. As shown in Fig. As shown in 2C, the particle size of the polystyrene particles produced according to Example 3 was approximately 580 nm and as shown in Fig. As shown in 2D, the particle size of the polystyrene particles produced according to Example 5 was approximately 1300 nm.

[0049] Furthermore, the surface charge of each type (e.g., type) of the in Fig.The polystyrene particles shown in Figures 2A-2D were measured by zeta potential measurement (Zetasizer, Malvern Instruments), and the results of the measurement are shown in Table 1 below. As shown in Table 1, positive surface charges were measured on all polystyrene particles produced in the examples of the present invention. Table 1 Type of polystyrene particle Particle diameter (nm) Surface charge value (mV) Example 4 90 +38.5 Example 2 200 +43.4 Example 3 580 +51.4 Example 5 1300 +45.0

[0050] Then, in step (b), production of silicon dioxide polystyrene particles (S200), the positively charged polystyrene particles and negatively charged silicon dioxide nanoparticles produced in step (a), production of polystyrene particles (S100), can be bonded together by electrostatic attraction to produce silicon dioxide polystyrene particles.

[0051] The silicon dioxide nanoparticles used in the examples of the present invention were YGS-30, YGS-40, YGS-4040 and YGS-4080, obtained from Young Chemical Industry Co. Ltd.

[0052] Fig. Figures 3A-3D show scanning electron microscope (SEM) images of the silicon dioxide nanoparticles used in the examples of the present invention. In particular, Fig. 3A a REM image of YGS-30; Fig. 3B a REM image of YGS-40; Fig. 3C a SEM image of YGS-4040; and Fig. 3D REM image of YGS-4080.

[0053] Furthermore, the size of each type (e.g., silicon dioxide nanoparticle) was measured by dynamic light scattering (DLS), and the surface charges of the silicon dioxide nanoparticles were measured by zeta potential measurement (Zetasizer, Malvern Instruments). The measurement results are shown in Table 2 below. Table 2 Type of silica nanoparticle Particle diameter (nm) Surface charge value (mV) YGS-30 20.62 -44.8 YGS-40 20.26 -44.3 YGS-4040 56.72 -46.3 YGS-4080 93.61 -48.9

[0054] In the process for producing the silicon dioxide-polystyrene particles according to the present invention, the silicon dioxide nanoparticles and the polystyrene particles can be stirred at a volume ratio of approximately 1:1, and then any excess silicon dioxide nanoparticles remaining without binding can be removed by centrifugation, thereby producing silicon dioxide-polystyrene particles. An exemplary process for producing the silicon dioxide-polystyrene particles is shown in Example 6 below. Example 6

[0055] 1 mL of a solution containing 0.4 wt% silicon dioxide nanoparticles, obtained by dispersing silicon dioxide nanoparticles (YGS-40 or YGS-4040) in distilled water, and 1 mL of a solution containing 0.04 wt% polystyrene particles, prepared by dispersing the polystyrene particles (prepared in Example 2) in distilled water, are vortex-stirred for 1 minute at a temperature of 25 °C and then centrifuged three times for 20 minutes each at 6000 rpm to remove excess silicon dioxide nanoparticles, producing silicon dioxide polystyrene particles.

[0056] The volume of the silicon dioxide nanoparticle solution or the polystyrene particle solution can be changed to 3 mL or 6 mL, if necessary, so that the volume ratio of the two solutions is 1:1.

[0057] Fig.Figures 4A-4D show silicon dioxide polystyrene particles produced according to the present invention. Fig. Figure 4A is a schematic view showing a process for producing silicon dioxide polystyrene particles, and Fig. Figures 4B to 4D show consecutive scanning electron microscope (SEM) images of polystyrene particles, silicon dioxide particles and silicon dioxide-polystyrene particles produced in Example 6.

[0058] As in Fig. As shown in Figure 4A, in step (b), the production of silicon dioxide polystyrene particles (S200), when negatively charged silicon dioxide nanoparticles are mixed with positively charged polystyrene particles and vortex-stirred for 1 minute, silicon dioxide polystyrene particles can be obtained by electrostatic attraction between the two types of particles.

[0059] As from Fig.In 4D, raspberry-shaped silicon dioxide polystyrene particles are formed, with silicon dioxide nanoparticles bonded to each polystyrene particle.

[0060] Furthermore, the surface charge of each type (e.g., type) of particle was measured before and after stirring in step (b), producing silicon dioxide-polystyrene particles (S200). As a result, as shown in Fig. Figures 3A-3D show that silicon dioxide-polystyrene particles were formed by the positively charged polystyrene particles and the negatively charged silicon dioxide nanoparticles. This result suggests that the polystyrene particles with the silicon dioxide nanoparticles bound to them were successfully produced. Table 3 PS particles silicon dioxide nanoparticles silicon dioxide polystyrene particles Surface charge value (mV) +43.4 -44.3 -43.1

[0061] Furthermore, factors affecting the process for manufacturing the silicon dioxide polystyrene particles were investigated, and the results are presented in the Fig.Shown 5 to 7.

[0062] Fig. Figures 5A-5F show scanning electron microscope (SEM) images of the shapes (e.g., external forms) of exemplary silicon dioxide polystyrene particles produced using various stirring methods and reaction temperatures in the step of manufacturing the silicon dioxide polystyrene particles according to the present invention.

[0063] In particular, the Fig. 5A and Fig. 5B the shape (e.g. external shape) of silicon dioxide polystyrene particles produced by vortex stirring for 1 minute at a temperature of 25 °C, according to the above-described method of stirring silicon dioxide nanoparticles and polystyrene particles according to Example 6.

[0064] Fig. 5C and Fig.Figure 5D shows the shape (e.g., external form) of silicon dioxide-polystyrene particles produced by ultrasonic stirring for 1 minute at a temperature of 25 °C, following the method of stirring silicon dioxide nanoparticles (YGS-40) and polystyrene particles, in the same way as in Example 6. By comparison with the Fig. 5A and Fig. Figure 5B shows that silicon dioxide polystyrene particles are formed with silicon dioxide nanoparticles, with the silicon dioxide nanoparticles adhering (only) partially to each polystyrene particle, indicating that the desired silicon dioxide polystyrene particles are not formed correctly.

[0065] When ultrasound is applied, the electrostatic attraction between silicon dioxide nanoparticles and polystyrene particles can be reduced, and therefore the desired silicon dioxide-polystyrene nanoparticles are not formed.

[0066] Fig. 5E and Fig. Figure 5F shows the shape (e.g., external form) of exemplary silicon dioxide-polystyrene particles produced by vortex stirring for 1 minute at a temperature of 100 °C, in the same manner as in the step of stirring silicon dioxide nanoparticles and polystyrene particles according to Example 6. In particular, silicon dioxide-polystyrene particles can be formed with silicon dioxide nanoparticles partially adhering to each polystyrene particle, indicating that the desired silicon dioxide-polystyrene particles are not being formed correctly.

[0067] Therefore, it can be confirmed that the process for producing the silicon dioxide nanoparticles and the polystyrene particles in step (b), producing silicon dioxide polystyrene particles (S200), according to the present invention is preferably vortex stirring at a reaction temperature of 25 °C.

[0068] Fig.Figures 6A-6G show scanning electron microscope (SEM) images of the shape (e.g., external shape) of exemplary silicon dioxide polystyrene particles produced using different size ratios of polystyrene particles to silicon dioxide nanoparticles, in the step of producing the silicon dioxide polystyrene particles according to various exemplary embodiments of the present invention.

[0069] For example, the Fig. 6A to 6D Silicon dioxide polystyrene particles, produced using silicon dioxide nanoparticles with a particle size of 20 nm together with polystyrene particles with particle sizes of 90 nm (6A), 200 nm (6B), 580 nm (6C) and 1300 nm (6D).

[0070] Fig.6E to 6G show silicon dioxide polystyrene particles produced using silicon dioxide nanoparticles with a particle size of 50 nm together with polystyrene particles with particle sizes of 200 nm (6E), 580 nm (6F) and 1300 nm (6G), respectively.

[0071] As in the Fig. As shown in Figures 6A-6G, it was observed that, in the case where polystyrene particles with a size of 90 nm were used, except when the size ratio of the polystyrene particles to silicon dioxide nanoparticles was 4.5 (6A), raspberry-shaped silicon dioxide polystyrene particles were formed when the size ratio of the polystyrene particles to silicon dioxide nanoparticles was 10 or more ( Fig.6B to 6D). It was also observed that, in the case where silicon dioxide nanoparticles with a particle size of 50 nm were used, except when the polystyrene particles had a particle size of 200 nm and the size ratio of the polystyrene particles to silicon dioxide nanoparticles was 4 (6E), raspberry-shaped silicon dioxide-polystyrene particles were formed when the size ratio of the polystyrene particles to silicon dioxide nanoparticles was 10 or 26 ( Fig. 6Fund 6G).

[0072] Therefore, it could be confirmed that when the size ratio of polystyrene particles to silicon dioxide nanoparticles was 10 or more, silicon dioxide-polystyrene particles were successfully formed.

[0073] Fig.Figures 7A-7H show scanning electron microscope (SEM) images of the shapes (e.g., external forms) of silicon dioxide polystyrene particles produced using different concentrations of aqueous sodium chloride (NaCl) solution, in the step of producing the silicon dioxide polystyrene particles according to the present invention.

[0074] To investigate the effect of the ionic strength between polystyrene particles and silicon dioxide particles on the production of raspberry-shaped silicon dioxide-polystyrene particles, different concentrations of an aqueous sodium chloride (NaCl) solution were added to a solution mixture of silicon dioxide nanoparticles (YGS-4040) with a size of 50 nm and polystyrene particles with a size of 200 nm (Example 2), thereby producing silicon dioxide-polystyrene particles. Fig. 7A and Fig.Figure 7B shows silicon dioxide polystyrene particles produced by adding 0.1 mmol / L aqueous sodium chloride solution; Fig. 7C and Fig. Figure 7D shows silicon dioxide polystyrene particles produced by adding 1.0 mmol / L aqueous sodium chloride solution; Fig. 7E and Fig. Figure 7F shows silicon dioxide polystyrene particles produced by adding 10.0 mmol / L aqueous sodium chloride solution; and Fig. 7G and Fig. Figure 7H shows silicon dioxide polystyrene particles produced by adding 100.0 mmol / L aqueous sodium chloride solution.

[0075] As from Fig. As can be seen in Figure 6E, when aqueous sodium chloride solution was added, the silicon dioxide particles were not bound to polystyrene particles, whereas, as shown in Figure 6E, Fig. 7A-7H shows that raspberry-shaped silicon dioxide polystyrene particles were formed upon addition of aqueous sodium chloride solution.

[0076] In particular, it was evident that with increasing concentration of the aqueous sodium chloride solution, from 0.1 mmol / L (7A and 7B) to 10.0 mmol / L (7E and 7F), the number of silicon dioxide nanoparticles bound to polystyrene particles increased. However, as was observed Fig. 7G and Fig. 7H shows that upon addition of 100.0 mmol / L aqueous sodium chloride solution, the particles agglomerate.

[0077] Therefore, it was confirmed that the addition of a suitable concentration of aqueous sodium chloride solution can influence the formation of silicon dioxide polystyrene particles. It is preferable to add less than approximately 100.0 mmol / L of sodium chloride solution.

[0078] As in Fig.As shown in Figure 8, in step (c), producing amphiphilic silicon dioxide nanoparticles (S300), amphiphilic silicon dioxide nanoparticles can be produced by subjecting the silicon dioxide polystyrene particles (produced in step (b), producing silicon dioxide polystyrene particles (S200)) to a first surface treatment, followed by a second surface treatment while removing the polystyrene particles.

[0079] The measurement results shown in Table 2 above indicate that silicon dioxide nanoparticles can have a negative surface charge value due to the presence of a hydroxyl group (-OH) on the particle surface.

[0080] Therefore, amphiphilic silicon dioxide nanoparticles can be produced by using the coupling reaction between an organic material with a carboxyl group (-COOH) and N,N'-dicyclohexylcarbodiimide (DCC) to chemically bind functional ligands to the silicon dioxide nanoparticle surface.

[0081] For the production of the amphiphilic silicon dioxide nanoparticles according to the invention, for example N-(tert-Butoxycarbonyl)-β-alanine (NBA), which has a carboxyl group together with an amine group for interaction with polyurethane, and perfluorooctanoic acid (PFOA), which has a functional fluorine group for improvement of the anti-fingerprint properties, are used as a functional ligand for the organic material.

[0082] According to an exemplary embodiment, as shown in Fig.Figure 10 shows that three types (e.g., types) of amphiphilic silicon dioxide nanoparticles can be produced as surface-treated amphiphilic silicon dioxide nanoparticles, depending on the types (e.g., types) of functional groups that are substituted in the first and second surface treatment processes.

[0083] In an exemplary embodiment, amphiphilic amine-fluoro-silicon dioxide particles with a functional amine group introduced during the first surface treatment and a functional fluorine group introduced during the second surface treatment are prepared as follows. For example, during the first surface treatment, N-(tert-butoxycarbonyl)-β-alanine (NBA), 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDAC), and 4-dimethylaminopyridine (DMAP) can be added to the silicon dioxide-polystyrene particles, and the mixture can be stirred at room temperature for 24 hours. Any excess of the remaining reagents can be removed by centrifugation.

[0084] The silicon dioxide-polystyrene particles that have undergone the first surface treatment can then be added to a tetrahydrofuran (THF) solvent, followed by the addition of perfluorooctanoic acid (PFOA), N,N'-dicyclohexylcarbodiimide (DCC), and 4-dimethylaminopyridine (DMAP). The mixture can be stirred for 24 hours at room temperature (approximately 20°C to 30°C), subjecting the silicon dioxide nanoparticles to a second surface treatment while removing the polystyrene particles. Any excess reagents remaining after the second surface treatment can be removed by centrifugation.

[0085] Exemplary processes for the production of amphiphilic amine-fluorine surface-treated silicon dioxide particles are shown below. Example 7

[0086] For the first surface treatment, 18.9 mg NBA, 19.17 mg EDAC, and 12.22 mg DMAP are added to 1 mL of a silicon dioxide polystyrene particle solution, and the mixture is stirred for 24 hours at room temperature (approximately 20 °C to 30 °C). After stirring, any excess reagent is removed by centrifugation three times for 20 minutes each at 6000 rpm. For the second surface treatment, the silicon dioxide polystyrene particles subjected to the first surface treatment are added to 1 mL of a THF solvent, and 41.4 mg PFOA, 20.6 mg DCC, and 12.22 mg DMAP are added, followed by stirring at room temperature for 24 hours. After stirring, any excess reagent is removed by centrifugation three times for 20 minutes each at 6000 rpm. Example 8

[0087] The amphiphilic amine-fluorine surface-treated silicon dioxide particles can be prepared in the same manner as in Example 7, except that the amounts of materials (e.g., reagents) added in the respective steps are changed, resulting in amphiphilic amine-fluorine surface-treated silicon dioxide particles. For example, for the first surface treatment, 56.7 mg NBA, 57.51 mg EDAC, and 36.33 mg DMAP are added to 3 mL of a silicon dioxide-polystyrene particle solution, and the mixture is stirred at room temperature for 24 hours. After stirring is complete, any excess reagents are removed by centrifugation three times for 20 minutes each at 6000 rpm.For the second surface treatment, the silicon dioxide-polystyrene particles that underwent the first surface treatment are added to 3 mL of a THF solvent, and 124.2 mg of PFOA, 61.8 mg of DCC, and 36.66 mg of DMAP are added, followed by stirring at room temperature for 24 hours. After stirring is complete, any excess reagents are removed by centrifugation three times for 20 minutes each at 6000 rpm. Example 9

[0088] The amphiphilic amine-fluorine surface-treated silicon dioxide particles can be prepared in the same manner as in Example 7, except that the amounts of materials (e.g., reagents) added in the respective steps are changed, resulting in amphiphilic amine-fluorine surface-treated silicon dioxide particles. For example, for the first surface treatment, 113.4 mg NBA, 115.02 mg EDAC, and 72.66 mg DMAP are added to 6 mL of a silicon dioxide-polystyrene particle solution, and the mixture is stirred at room temperature for 24 hours. After stirring is complete, any excess reagents are removed by centrifugation three times for 20 minutes each at 6000 rpm.For the second surface treatment, the silicon dioxide-polystyrene particles that underwent the first surface treatment are added to 3 mL of a THF solvent, and 248.4 mg of PFOA, 123.6 mg of DCC, and 73.32 mg of DMAP are added, followed by stirring at room temperature for 24 hours. After stirring is complete, any excess reagents are removed by centrifugation three times for 20 minutes each at 6000 rpm.

[0089] In a further embodiment of the method for producing amphiphilic silicon dioxide particles of the present invention, amphiphilic fluoroamine surface-treated silicon dioxide particles with a functional fluorine group introduced in a first surface treatment and a functional amine group introduced in a second surface treatment can be produced as follows. For example, for the first surface treatment, PFOA, DCC, and DMAP reagents can be added to the silicon dioxide polystyrene particles dispersed in an ethanol solvent, and the mixture is stirred for 24 hours at room temperature (about 20°C to 30°C). Any excess of the reagents can be removed by centrifugation.Subsequently, for the second surface treatment, the silicon dioxide polystyrene particles that underwent the first surface treatment can be added to a tetrahydrofuran (THF) solvent, and NBA, DCC, and DMAP reagents can be added, followed by stirring at room temperature (approximately 20°C to 30°C) for 24 hours. Any excess reagents can be removed by centrifugation.

[0090] Exemplary processes for the production of amphiphilic fluorine surface-treated silicon dioxide particles are shown below. Example 10

[0091] For the first surface treatment, 41.4 mg PFOA, 20.6 mg DCC, and 12.22 mg DMAP are added to 1 mL of a solution of silicon dioxide polystyrene particles dispersed in an ethanol solvent, and the mixture is stirred at room temperature for 24 hours. After stirring, any excess reagents are removed by centrifugation three times for 20 minutes each at 6000 rpm. For the second surface treatment, the silicon dioxide polystyrene particles subjected to the first surface treatment are added to 1 mL of a THF solvent, and 18.9 mg NBA, 20.6 mg DCC, and 12.22 mg DMAP are added, followed by stirring at room temperature for 24 hours. After stirring is complete, any excess of reagents is removed by centrifuging three times for 20 minutes each time at 6000 rpm. Example 11

[0092] The amphiphilic fluoroamine surface-treated silicon dioxide particles can be prepared in the same manner as in Example 10, except that the amounts of materials (e.g., reagents) added in the respective steps are changed, resulting in amphiphilic fluoroamine surface-treated silicon dioxide particles. For example, for the first surface treatment, 124.2 mg of PFOA, 61.8 mg of DCC, and 36.66 mg of DMAP are added to 3 mL of a solution of silicon dioxide polystyrene particles dispersed in an ethanol solvent, and the mixture is stirred at room temperature for 24 hours. After stirring is complete, any excess reagents are removed by centrifugation three times for 20 minutes each at 6000 rpm.For the second surface treatment, the silicon dioxide-polystyrene particles that underwent the first surface treatment are added to 3 mL of a THF solvent, and 56.7 mg NBA, 61.8 mg DCC, and 36.66 mg DMAP are added, followed by stirring at room temperature for 24 hours. After stirring is complete, any excess reagents are removed by centrifugation three times for 20 minutes each at 6000 rpm. Example 12

[0093] The amphiphilic fluoroamine surface-treated silicon dioxide particles can be prepared in the same manner as in Example 10, except that the amounts of materials (e.g., reagents) added in the respective steps are changed, resulting in amphiphilic fluoroamine surface-treated silicon dioxide particles. For example, for the first surface treatment, 248.4 mg of PFOA, 123.6 mg of DCC, and 72.66 mg of DMAP are added to 6 mL of a solution of silicon dioxide polystyrene particles dispersed in an ethanol solvent, and the mixture is stirred at room temperature for 24 hours. After stirring is complete, any excess reagents are removed by centrifugation three times for 20 minutes each at 6000 rpm.For the second surface treatment, the silicon dioxide-polystyrene particles that underwent the first surface treatment are added to 3 mL of a THF solvent, and 113.4 mg NBA, 123.6 mg DCC, and 73.32 mg DMAP are added, followed by stirring at room temperature for 24 hours. After stirring is complete, any excess reagents are removed by centrifugation three times for 20 minutes each at 6000 rpm.

[0094] In further embodiments of the process for producing amphiphilic silicon dioxide particles, amphiphilic fluorohydroxy surface-treated silicon dioxide particles with a fluorine functional group introduced during a first surface treatment are prepared as follows. For example, for the first surface treatment, PFOA, DCC, and DMAP reagents are added to silicon dioxide polystyrene particles dispersed in an ethanol solvent, and the mixture is stirred for 24 hours at room temperature (about 20°C to 30°C). Any excess of the reagents is removed by centrifugation. Silicon dioxide polystyrene particles that have undergone the first surface treatment are added to a tetrahydrofuran (THF) solvent and then stirred for 24 hours at room temperature (about 20°C to 30°C) to remove the polystyrene particles.Silicon dioxide nanoparticles surface-treated with a functional fluorohydroxy group are collected by centrifugation.

[0095] Exemplary processes for the production of amphiphilic fluorohydroxy surface-treated silicon dioxide particles are shown below. Example 13

[0096] For the first surface treatment, 41.4 mg PFOA, 20.6 mg DCC, and 12.22 mg DMAP are added to 1 mL of a solution of silicon dioxide polystyrene particles dispersed in an ethanol solvent, and the mixture is stirred at room temperature for 24 hours. After stirring, any excess reagents are removed by centrifugation three times for 20 minutes each at 6000 rpm. The silicon dioxide polystyrene particles subjected to the first surface treatment are added to a tetrahydrofuran solvent and then stirred at room temperature for 24 hours to remove the polystyrene particles. Amphiphilic fluorohydroxy surface-treated silicon dioxide particles are collected by centrifugation three times for 20 minutes each at 13000 rpm. Example 14

[0097] The amphiphilic fluorohydroxy surface-treated silicon dioxide particles can be prepared in the same manner as in Example 13, except that the amounts of materials (e.g., reagents) added in the respective steps are changed, resulting in amphiphilic fluorohydroxy surface-treated silicon dioxide particles. For example, for the first surface treatment, 124.2 mg of PFOA, 61.8 mg of DCC, and 36.66 mg of DMAP are added to 3 mL of a solution of silicon dioxide polystyrene particles dispersed in an ethanol solvent, and the mixture is stirred at room temperature for 24 hours. After stirring is complete, any excess reagents are removed by centrifugation three times for 20 minutes each at 6000 rpm.The silicon dioxide polystyrene particles that underwent the first surface treatment are added to a tetrahydrofuran (THF) solvent and then stirred at room temperature for 24 hours to remove the polystyrene particles. Amphiphilic fluorohydroxy surface-treated silicon dioxide particles are collected by centrifugation three times for 20 minutes each at 13,000 rpm. Example 15

[0098] The amphiphilic fluorohydroxy surface-treated silicon dioxide particles can be prepared in the same manner as in Example 13, except that the amounts of materials (e.g., reagents) added in the respective steps are changed, resulting in amphiphilic fluorohydroxy surface-treated silicon dioxide particles. For example, for the first surface treatment, 248.4 mg of PFOA, 123.6 mg of DCC, and 72.66 mg of DMAP are added to 6 mL of a solution of silicon dioxide polystyrene particles dispersed in an ethanol solvent, and the mixture is stirred at room temperature for 24 hours. After stirring is complete, any excess reagents are removed by centrifugation three times for 20 minutes each at 6000 rpm.The silicon dioxide polystyrene particles that underwent the initial surface treatment are added to a tetrahydrofuran (THF) solvent and then stirred at room temperature for 24 hours to remove the polystyrene particles. Amphiphilic fluorohydroxy surface-treated silicon dioxide particles are collected by centrifugation three times for 20 minutes each at 13,000 rpm.

[0099] Fig. Figures 11A-11D show scanning electron microscope (SEM) images of exemplary particles produced by the first and second surface treatment processes in the step of producing amphiphilic silicon dioxide nanoparticles of the present invention.

[0100] Fig. 11A and Fig.Figure 11B shows the results of observing the shape (e.g., external form) of the particles remaining after subjecting the silicon dioxide-polystyrene particles to a first surface treatment. As can be seen, the raspberry-shaped silicon dioxide-polystyrene particles were retained along with silicon dioxide particles bonded to polystyrene particles. Fig. 11C and Fig. Figure 11D shows the shape (e.g., external shape) of the particles that remain after the removal of the polystyrene particles and the execution of the second surface treatment, and, as can be seen, the polystyrene particles were removed and only the silicon dioxide nanoparticles remained.

[0101] To investigate whether the silicon dioxide nanoparticles produced by the surface treatment described above exhibit amphiphilicity (hydrophobicity and hydrophilicity), a test was performed using a polar-nonpolar emulsion, and the results of the test are presented in the Fig. 12A-12E shown.

[0102] If the manufactured silicon dioxide nanoparticles exhibit amphiphilicity, they act as a surfactant, and therefore amphiphilicity can be indirectly confirmed by the formation of an emulsion at the polar (water) / nonpolar (oil) interface. For this emulsion test, water was used as the polar solution and chloroform as the nonpolar solution.

[0103] Fig. 12A shows silicon dioxide nanoparticles before surface treatment; Fig. Figure 12B shows silicon dioxide nanoparticles surface-treated with only one functional amine group; Fig.12C shows silicon dioxide nanoparticles that are surface-treated with only one functional fluorine group; Fig. Figure 12D shows amphiphilic amine-fluorine surface-treated silicon dioxide nanoparticles; and Figure 12E is a schematic view showing an emulsion formed by amphiphilic, surface-treated silicon dioxide nanoparticles.

[0104] One result is, as in Fig. Figure 12D shows that only amphiphilic, surface-treated silicon dioxide nanoparticles formed an emulsion. This result suggests that amphiphilic silicon dioxide nanoparticles were successfully formed in the examples of the present invention.

[0105] In step (d), producing a heat-curable coating composition based on polyurethane-silicon dioxide composite (S400), the amphiphilic silicon dioxide nanoparticles produced in step (c), producing amphiphilic silicon dioxide nanoparticles (S300), can be mixed with polyurethane, thereby producing a heat-curable coating composition based on polyurethane-silicon dioxide composite.

[0106] In an exemplary embodiment, the heat-curable coating composition based on polyurethane-silicon dioxide composite can be produced by mixing polyurethane (provided by Noroo Bee Chemical Co., Ltd.) with a curing agent in a predetermined ratio and adding and mixing surface-treated silicon dioxide nanoparticles dispersed in 0.5 mL of tetrahydrofuran (THF) to the solution mixture.

[0107] In particular, the components and their contents of each of the heat-curable coating compositions based on polyurethane-silicon dioxide composite are shown in Table 4 below.

[0108] Next, in step (e), producing a polyurethane-silicon dioxide composite film (S500), the polyurethane-silicon dioxide composite film can be formed by applying the produced, heat-curable coating composition based on polyurethane-silicon dioxide composite to the surface of a specific substrate and curing the applied composition.

[0109] In an exemplary embodiment, as shown in Fig.Figure 13 shows that each of the heat-curable coating compositions based on polyurethane-silicon dioxide composite, which were produced to have the components and contents shown in Table 4 below, are rod-coated (e.g., rod-coated) onto an acrylonitrile butadiene styrene (ABS) substrate using a glass rod and cured at a temperature of about 60 to 90°C, resulting in a polyurethane-silicon dioxide composite film.

[0110] The thickness of the resulting polyurethane-silicon dioxide composite film varies depending on the amounts of polyurethane and hardening agent used and the weight fraction of silicon dioxide nanoparticles in the heat-curable coating composition based on polyurethane-silicon dioxide composite. Table 4 Composite material 1 Composite material 2 Composite material 3 Composite material 4 Polyurethan 1.5 g 0.3 g 0.3 g 0.15 g hardening agents 0.5 g 0.1 g 0.1 g 0.05 g silicon dioxide nanoparticles 0.006 g 0.006 g 0.024 g 0.024 g Foil thickness 40 µm 20 µm 20 µm 10 µm weight fraction silicon dioxide nanoparticles 0.3 wt% 1.5 wt% 5.7 wt% 10.7wt%

[0111] Fig.Figures 14A-14E show the change in the gloss of the polyurethane-silicon dioxide composite film when the weight fraction of amphiphilic silicon dioxide nanoparticles is changed. For example, Fig. 14A the transmittance of a conventional polyurethane film; Fig. Figure 14B shows the transmittance of the polyurethane-silicon dioxide composite film produced using the heat-curable coating composition based on polyurethane-silicon dioxide composite according to composite 1; Fig. Figure 14C shows the transmittance of the polyurethane-silicon dioxide composite film produced using the heat-curable coating composition based on polyurethane-silicon dioxide composite according to composite 2; Fig.Figure 14D shows the transmittance of the polyurethane-silicon dioxide composite film produced using the heat-curable coating composition based on polyurethane-silicon dioxide composite according to composite 3; Fig. Figure 14E shows the transmittance of the polyurethane-silicon dioxide composite film produced using the heat-curable coating composition based on polyurethane-silicon dioxide composite material according to composite material 4. The transmittance was measured by UV-Vis spectroscopy.

[0112] As in the Fig. Figures 14A to 14E show that transparent films were produced, regardless of the type (e.g., type) of amphiphilic silicon dioxide nanoparticles.

[0113] As in the Fig.As shown in Figures 15A-15B, the films exhibited a similar (e.g., identical) trend. This suggests that the amphiphilic silicon dioxide nanoparticles do not affect the transparency of the polyurethane film.

[0114] However, the polyurethane-silicon dioxide composite film according to composite material 4, which contained 10.7 wt% of the silicon dioxide nanoparticles, exhibited a noticeably low gloss. A film thickness of 10 µm was measured.

[0115] Accordingly, since the polyurethane-silicon dioxide composite film produced in the present invention should retain the gloss of a conventional polyurethane film, the surface properties of films formed using the coating compositions of the composites 1 to 3 and the phase separation of the polyurethane-silicon dioxide composite films formed using different types (e.g. types) of silicon dioxide nanoparticles were investigated.

[0116] Fig. Figure 16 shows the results of the measurement of the water contact angles of polyurethane-silicon dioxide composite films. In particular, it shows Fig. 16 the contact angle properties of polyurethane-silicon dioxide composite films produced using non-surface-treated silicon dioxide nanoparticles (hereinafter referred to as “OH”), amphiphilic amine-fluorine surface-treated silicon dioxide nanoparticles (hereinafter referred to as “NH2-F”) or amphiphilic fluorine surface-treated silicon dioxide nanoparticles (hereinafter referred to as “F-NH2”) and cured at 80 °C.

[0117] As in Fig.As shown in Figure 16, the measured contact angle of the surface of the polyurethane-silicon dioxide composite film produced using the amphiphilic amine-fluorine surface-treated silicon dioxide nanoparticles (NH2-F) or the fluoro-amine surface-treated silicon dioxide nanoparticles (F-NH2) was larger than that of the polyurethane-silicon dioxide composite film produced using the unsurface-treated silicon dioxide nanoparticles (OH). Among these films, a relatively high contact angle was measured for the polyurethane-silicon dioxide composite film produced using the fluoro-amine surface-treated silicon dioxide nanoparticles (F-NH2), which were surface-treated with a relatively large amount of functional fluorine groups. Furthermore, the contact angle of the polyurethane-silicon dioxide composite film showed a tendency to increase as the amount of surface-treated, amphiphilic silicon dioxide nanoparticles increased.

[0118] These results of the contact angle property measurements indirectly suggest that phase separation of the amphiphilic silicon dioxide nanoparticles can occur in the exemplary polyurethane-silicon dioxide composite film.

[0119] To investigate the surface properties of the polyurethane-silicon dioxide composite film, the appearance of the film's surface was examined using atomic force microscopy (AFM), and the results are presented in the Fig. 17 and Fig. 18 shown.

[0120] Fig. Figure 17A shows the polyurethane-silicon dioxide composite film, which was produced by curing the heat-curable coating compositions based on polyurethane-silicon dioxide composite, containing 0.3 wt% of the amphiphilic amine-fluorine surface-treated silicon dioxide nanoparticles (NH2-F), at a temperature of 80 °C and Fig.Figure 17B shows the polyurethane-silicon dioxide composite film produced by curing the heat-curable coating compositions based on polyurethane-silicon dioxide composite containing 0.3 wt% of the amphiphilic fluoroamine surface-treated silicon dioxide nanoparticles (F-NH2) at a temperature of 80 °C.

[0121] As in the Fig.As shown in Figures 17A-17B, no silicon dioxide nanoparticles were observed on the surface of the polyurethane-silicon dioxide composite film produced using amphiphilic amine-fluorine surface-treated silicon dioxide nanoparticles (NH2-F), whereas silicon dioxide nanoparticles were observed on the surface of the polyurethane-silicon dioxide composite film produced using amphiphilic fluorine surface-treated silicon dioxide nanoparticles (F-NH2). The height of the silicon dioxide nanoparticles on the film surface was measured and ranged from 4 to 10 nm.

[0122] Fig.Figure 18A shows the polyurethane-silicon dioxide composite film, which was produced by curing the heat-curable coating compositions based on polyurethane-silicon dioxide composite, containing 5.7 wt% of the amphiphilic amine-fluorine surface-treated silicon dioxide nanoparticles (NH2-F), at a temperature of 80 °C and Fig. Figure 18B shows the polyurethane-silicon dioxide composite film produced by curing the heat-curable coating compositions based on polyurethane-silicon dioxide composite containing 5.7 wt% of amphiphilic fluoroamine surface-treated silicon dioxide nanoparticles (F-NH2) at a temperature of 80 °C.

[0123] As in the Fig.As shown in Figures 18A-18B, when the amount of amphiphilic silicon dioxide nanoparticles was increased, silicon dioxide nanoparticles could be observed both on the surface of the polyurethane-silicon dioxide composite film produced using the amphiphilic amine-fluorine surface-treated silicon dioxide nanoparticles (NH2-F) and on the surface of the polyurethane-silicon dioxide composite film produced using the amphiphilic fluorine surface-treated silicon dioxide nanoparticles (F-NH2).

[0124] In this case, the height of the silicon dioxide nanoparticles on the film surface was approximately 4 to 6 nm for the polyurethane-silicon dioxide composite film produced using the amphiphilic amine-fluorine surface-treated silicon dioxide nanoparticles (NH2-F) and approximately 4 to 10 nm for the polyurethane-silicon dioxide composite film produced using the amphiphilic fluorine-amine surface-treated silicon dioxide nanoparticles (F-NH2).

[0125] These results suggest that phase separation of amphiphilic silicon dioxide nanoparticles can occur in the polyurethane-silicon dioxide composite film produced using surface-treated amphiphilic silicon dioxide nanoparticles. In particular, phase separation of silicon dioxide nanoparticles can readily occur in the polyurethane-silicon dioxide composite film produced using fluoroamine surface-treated silicon dioxide nanoparticles. This phase separation in the polyurethane-silicon dioxide composite film is in Fig. 19 shown.

[0126] Furthermore, in order to compare the effective (e.g., actual) phase separation between different curing processes in step (e), producing a polyurethane-silicon dioxide composite film (S500), as described in Fig.Figure 20A shows that polyurethane-silicon dioxide composite films were produced using 5.7 wt% of amphiphilic fluorine surface-treated silicon dioxide nanoparticles (F-NH2) and various curing methods. The curing methods (1-3) used were a closed system on a hot plate, an open system on a hot plate, and a convection oven for measurement.

[0127] Although not shown in the figures, when comparing the contact angle properties of the polyurethane-silicon dioxide composite films produced by the different manufacturing processes, it was measured that the polyurethane-silicon dioxide composite film cured by the open system on the heating plate has a relatively high contact angle.

[0128] Furthermore, in order to investigate the contact angle properties of different sizes of silicon dioxide nanoparticles, silicon dioxide nanoparticles with sizes of approximately 20 nm and 50 nm were subjected to an amphiphilic surface treatment, and these particles were mixed according to the composition of composite 3, thereby producing polyurethane-silicon dioxide composite films. The contact angle properties of the produced films were measured.

[0129] As a result, the size of the silicon dioxide nanoparticles had no significant influence on the contact angle, since the agglomeration of the phase-separated silicon dioxide nanoparticles prevents the formation of a non-uniform surface structure, as demonstrated by atomic force microscopy (AFM) in Fig. 18A-18B shown.

[0130] Furthermore, to investigate the effect (e.g., influence) of fluoroamine surface-treated silicon dioxide nanoparticles or fluorohydroxy surface-treated silicon dioxide nanoparticles on phase separation, polyurethane-silicon dioxide composite films can be produced using the amphiphilic fluoroamine surface-treated silicon dioxide nanoparticles (F-NH2) or the amphiphilic fluorohydroxy surface-treated silicon dioxide nanoparticles (F-OH). The contact angle properties of the produced films were compared, and the results are presented in Fig. 20B or Fig. 20°C shown.

[0131] As in the Fig. 20B and Fig. At 20C, it was measured that the polyurethane-silicon dioxide composite film produced using amphiphilic fluoroamine surface-treated silicon dioxide nanoparticles has a relatively high contact angle.

[0132] Fig.Figures 21A-21B show the atomic force microscope (AFM) images of the surfaces of the polyurethane-silicon dioxide composite films produced using the amphiphilic fluoroamine surface-treated silicon dioxide nanoparticles (F-NH2) and the amphiphilic fluorohydroxy surface-treated silicon dioxide nanoparticles (F-OH), respectively.

[0133] As in Fig.As shown in Figure 21A, silicon dioxide nanoparticles were observed on the surface of both the polyurethane-silicon dioxide composite film produced using amphiphilic fluoroamine surface-treated silicon dioxide nanoparticles (F-NH2) and the polyurethane-silicon dioxide composite film produced using amphiphilic fluorohydroxy surface-treated silicon dioxide nanoparticles (F-OH). A relatively large quantity of silicon dioxide nanoparticles was observed on the polyurethane-silicon dioxide composite film produced using amphiphilic fluoroamine surface-treated silicon dioxide nanoparticles (F-NH2).Furthermore, the measured height of the silicon dioxide nanoparticles on the film surface was approximately 4 to 10 nm for the polyurethane-silicon dioxide composite film produced using the amphiphilic fluoroamine surface-treated silicon dioxide nanoparticles (F-NH2), but approximately 6 to 19 nm for the polyurethane-silicon dioxide composite film produced using the amphiphilic fluorohydroxy surface-treated silicon dioxide nanoparticles (F-OH).

[0134] This suggests that fluoroamine surface-treated silicon dioxide nanoparticles (F-NH2), exploiting the phase separation of a polyurethane film, can be effectively used in the production of an anti-fingerprint film.

[0135] Additionally, a section (e.g., cut, e.g., area) of a polyurethane-silicon dioxide composite film, produced using the composition of composite 3 and containing the amphiphilic fluoroamine surface-treated silicon dioxide nanoparticles (F-NH2) or the amphiphilic fluorohydroxy surface-treated silicon dioxide nanoparticles (F-OH), was examined using a scanning electron microscope (SEM) to confirm the phase separation of the polyurethane-silicon dioxide composite film. The results are presented in the Fig. 22A-22F shown.

[0136] As a result, as in Fig. As shown in Figure 22A, many silicon dioxide nanoparticles were observed on the surface of the polyurethane-silicon dioxide composite film, which was fabricated using the amphiphilic fluoroamine surface-treated silicon dioxide nanoparticles (F-NH2). However, as shown in Fig.22F showed that, in the case of the polyurethane-silicon dioxide composite film which has the amphiphilic fluoro-hydroxy surface-treated silicon dioxide nanoparticles (F-NH2), silicon dioxide nanoparticles could be observed on the underside of the film but not on the top side of the film.

[0137] Furthermore, the section (e.g., cut, e.g., area) of the composite film produced using fluoroamine surface-treated silicon dioxide nanoparticles (F-NH2) was examined with a scanning electron microscope (SEM) to confirm whether phase separation of the polyurethane-silicon dioxide composite film occurs. The results are presented in the Fig. 22A-22F shown. For this purpose, Pt sputtering was carried out, the foil was microtomized to a thickness of about 50 nm and the section (e.g. section, e.g. area) was examined by transmission electron microscopy (TEM).

[0138] As a result, as in Fig.Figures 23A-23G show silicon dioxide nanoparticles observed near the surface of the polyurethane-silicon dioxide composite film. Upon examining the magnified images of different areas ( Fig. 23B, Fig. 23C, Fig. 23E, Fig. 23F and Fig. 23G), there were also areas with silicon dioxide nanoparticles and areas without silicon dioxide nanoparticles. These results are consistent with atomic force microscopy (AFM) and scanning electron microscopy (SEM) images, which show that silicon dioxide nanoparticles were partially observed on the film surface.

[0139] Accordingly, in the process for producing the polyurethane-silicon dioxide composite film by curing the heat-curable coating composition based on polyurethane-silicon dioxide composite of the present invention, phase separation of the surface-treated, amphiphilic silicon dioxide nanoparticles occurred.

[0140] Furthermore, to investigate elemental components in the transmission electron microscopy (TEM) image of the section (e.g., cut, e.g., area) of the polyurethane-silicon dioxide composite film, energy-dispersive X-ray spectroscopy (EDS) was performed, and the results are presented in the Fig. 24A-24E shown.

[0141] As in Fig. 24A-24E showed that Si, O and Pt components could be detected, indicating that silicon dioxide nanoparticles were present on the film surface.

[0142] The heat-curable coating composition based on a polyurethane-silicon dioxide composite, produced according to various exemplary embodiments of the present invention, can exhibit improved anti-fingerprint properties, and the polyurethane-silicon dioxide composite film can be obtained with improved anti-fingerprint properties. Furthermore, the composition and the film can undergo phase separation as a result of mixing the amphiphilic silicon dioxide nanoparticles with polyurethane, thus providing improved contact angle properties by forming an uneven surface structure. In particular, among various types of amphiphilic silicon dioxide nanoparticles, fluoroamine surface-treated silicon dioxide nanoparticles can be suitable for inducing phase separation in the composite film.

[0143] As described above, to produce the heat-curable coating composition based on polyurethane-silicon dioxide composite of the present invention, amphiphilic silicon dioxide nanoparticles can be produced by selective surface treatment of silicon dioxide-polystyrene particles, which are composite particles (e.g., composite particles) made of silicon dioxide nanoparticles and polystyrene (PS). In an exemplary embodiment, the produced amphiphilic silicon dioxide nanoparticles can be mixed with polyurethane, thereby producing the heat-curable coating composition based on polyurethane-silicon dioxide composite.As such, the stability of a coating layer formed from the composition and the phase separation of the silicon dioxide nanoparticles can be optimized depending on the mixing ratio between the silicon dioxide nanoparticles and the polyurethane and the curing conditions under heat.

[0144] When the heat-curable coating composition based on a polyurethane-silicon dioxide composite with improved anti-fingerprint properties, produced according to exemplary embodiments of the present invention, is used, phase separation can occur in a coating layer formed from the composition, and thus two coating layers can be produced by a single coating process. In particular, delamination between the layers formed by phase separation can be minimized, since they are essentially chemically bonded at their interface. Furthermore, when the heat-curable coating composition based on a polyurethane-silicon dioxide composite according to the present invention is used, a polyurethane film with excellent anti-fingerprint and transparency properties can be produced by a simpler process.

[0145] Furthermore, polyurethane and silicon dioxide nanoparticles are used in various embodiments of the present invention, which are widely used in various industrial fields and can be easily mass-produced at low cost.

[0146] Although the exemplary embodiments of the present invention have demonstrated their superiority through the examples described above, the present invention is not necessarily limited to these embodiments, and various substitutions, modifications, and alterations are possible without departing from the technical concept of the present invention. Therefore, the foregoing description is not intended to limit the scope of the present invention as defined in the appended claims.

Claims

[1] Method for producing a polyurethane-silicon dioxide composite film, comprising the steps: (a) Production of polystyrene particles; (b) Production of silicon dioxide polystyrene particles by mixing the polystyrene particles with silicon dioxide nanoparticles; (c) Producing amphiphilic silicon dioxide nanoparticles by subjecting the silicon dioxide polystyrene particles to a first surface treatment, removing the polystyrene particles and then subjecting the remaining silicon dioxide nanoparticles to a second surface treatment, (d) Producing a coating composition by mixing the amphiphilic silicon dioxide nanoparticles with polyurethane; and (e) Applying the coating composition to a surface of a substrate to form a coating layer and hardening the coating layer, the procedure further includes in step (a): Producing a styrene-fluid mixture by introducing a styrene monomer and a solvent into a reactor and stirring under a nitrogen atmosphere for a predetermined time; and Heating the styrene-fluid mixture to a temperature of 60 °C to 70 °C and Addition of an initiator to the reactor and reaction of the styrene-fluid mixture with the initiator, wherein the initiator comprises 2,2'-Azobis(2-methylpropionamidine)dihydrochloride. [2] Method according to claim 1, further comprising in step (b): Production of silicon dioxide polystyrene particles by mixing and stirring a polystyrene solution containing polystyrene particles with a first silicon dioxide solution containing silicon dioxide nanoparticles in a volume ratio of 1:1 for a predetermined time. [3] Method according to one of the preceding claims 1 or 2, further comprising in step (b): Addition of a sodium chloride solution with a concentration of 0.1 mmol / L to 10.0 mmol / L to the mixture of the polystyrene solution and the first silicon dioxide solution. [4] Method according to any one of the preceding claims 1 to 3, further comprising in step (c): Subjecting the silicon dioxide polystyrene particles to a first surface treatment by adding the silicon dioxide polystyrene particles either to i) a first compound containing N-(tert-butoxycarbonyl)-β-alanine with a carboxyl group and an amine group, or to ii) a second compound containing perfluorooctanoic acid with a carboxyl group and an amine group, or to iii) a second compound with a functional carboxyl group and a functional fluorine group, and stirring the same; After the first surface treatment, add the silicon dioxide polystyrene particles to tetrahydrofuran and remove the polystyrene particles; and Subjecting the silicon dioxide particles remaining after the first surface treatment following the removal of the polystyrene particles to a second surface treatment by adding the silicon dioxide particles to a compound, wherein the compound comprises the first compound or the second compound which was not used in the first surface treatment, and stirring the silicon dioxide particles and the compound. [5] Method according to any one of the preceding claims 1 to 4, further comprising in step (d): Producing a second silicon dioxide solution by dispersing the amphiphilic silicon dioxide nanoparticles in tetrahydrofuran; To prepare a polyurethane solution containing polyurethane and a hardening agent; and Producing the coating composition by mixing the polyurethane solution with the second silicon dioxide solution, wherein the coating composition contains the silicon dioxide nanoparticles in an amount of 0.3 wt.% to 10.7 wt.%, based on the total weight of the coating composition. [6] Method according to any one of the preceding claims 1 to 5, wherein in step (e) the coating layer is cured at a temperature of 60 °C to 90 °C.

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