Hollow silica particles and a composition comprising the same

Abstract

The present invention relates to hollow silica particles, characterized by having Type IV adsorption / desorption characteristics in nitrogen isothermal adsorption / desorption, having a closing point at a relative pressure of 0.75 to 0.85, and having an excellent particle dispersion index. The hollow silica particles according to the present invention have significantly excellent particle uniformity, thereby providing excellent utility in various application fields.

Description

Technology Field

[0001] The present invention relates to hollow silica particles and a composition containing the same. Background Technology

[0002] Hollow silica particles are widely used in various industrial fields due to their unique hollow structure, chemical stability, high specific surface area, and low density. Hollow silica particles are used as key materials in applications such as drug delivery systems, catalysts, adsorbents, sensors, optical materials, films, thermal shields, and cosmetics.

[0003] Hollow structures provide the flexibility to adjust the physical and chemical properties of applications and can offer novel functionalities that conventional silica particles cannot provide. Specifically, due to their hollow structure, hollow silica particles can offer low density and a high specific surface area. Furthermore, particle size, wall thickness, and pore size can be precisely controlled depending on synthesis conditions, making them highly useful for a wide range of applications. Moreover, the surface of the silica particles can be substituted with various chemical functional groups, which allows for the adjustment of hydrophilicity or hydrophobicity and can also impart biocompatibility. For example, in pharmaceutical or cosmetic compositions, the internal space of the hollow silica particles can serve as a storage space for drugs or bioactive substances, while the external surface of the silica particles can be bonded with functional groups or ligands suitable for the application to provide functionality.

[0004] However, the introduction of a hollow structure has the disadvantage of requiring a complex manufacturing process, and since particle size, wall thickness, and pore structure change easily even with minute variations in the manufacturing process, there are limitations in uniformly maintaining and precisely controlling the physicochemical properties of hollow silica particles.

[0005] Due to the versatility of silica particles and the advantages of their hollow structure, the potential applications of hollow silica particles are steadily expanding, and their utility is increasing, particularly in the field of convergence with eco-friendly fine chemical materials and biomaterials. Therefore, there is a demand for the development of high-quality hollow silica capable of meeting diverse requirements for applications ranging from high-performance fine chemicals or biomaterials, as well as traditional applications utilizing physicochemical properties derived from the hollow structure. Prior art literature

[0006] Japanese Registered Patent JP 7218651 B2 The problem to be solved

[0007] One aspect of the present invention is to provide hollow silica having excellent physicochemical properties in various applications.

[0008] One aspect of the present invention is to provide hollow silica having low refractive index, low dielectric constant, and excellent wear resistance, and capable of forming a coating film having uniform low refractive index and low reflection optical properties when applied to a coating film. means of solving the problem

[0009] A hollow silica particle according to one embodiment of the present invention is characterized by having Type IV adsorption / desorption characteristics in nitrogen isothermal adsorption / desorption, having a closing point at a relative pressure of 0.75 to 0.85, and having a particle dispersion index of 1.7 or higher as indicated by Formula 1 below.

[0010] [Equation 1]

[0011] D V / FWHM V

[0012] D in Equation 1 above V represents the volume-averaged particle size determined by dynamic light scattering analysis, and FWHM V represents the maximum full width at half maximum of hollow silica particles in the volumetric particle size distribution graph.

[0013] In a hollow silica particle according to one embodiment, the hollow silica particle may have a hollow dispersion index represented by Formula 2 below of 1.5 or higher.

[0014] [Equation 2]

[0015] D h / FWHM h

[0016] (D in Equation 2 above h represents the average diameter of the hollow obtained from the transmission electron microscope image, and FWHM h (represents the full width at half maximum in the hollow size distribution graph)

[0017] In a hollow silica particle according to one embodiment, the volume average particle size (D) of the hollow silica particle V ) and number average particle size (D n The ratio of ) (D V / D n ) can satisfy 1 to 1.3.

[0018] In a hollow silica particle according to one embodiment, the BET specific surface area of ​​the hollow silica particle is 50 to 100 m² 2 / g and the pore volume is 0.4 to 0.6 cm³ 3 It can be / g.

[0019] In a hollow silica particle according to one embodiment, the average pore diameter calculated by the nitrogen desorption standard BJH method of the hollow silica particle may be 20 to 30 nm.

[0020] In a hollow silica particle according to one embodiment, in a graph of the differential value of the pore volume with respect to the pore diameter on a log scale and the pore diameter on a log scale due to BJH of the hollow silica particle, a single peak may be present in the range of pore diameters from 2 to 50 nm.

[0021] In a hollow silica particle according to one embodiment, the volume average particle size (D) of the hollow silica particleV ) is 60 to 90 nm, and the average diameter of the hollow (D h ) can be 50 to 80 nm.

[0022] In a hollow silica particle according to one embodiment, the absolute value of the zeta potential of the hollow silica particle may be 40 mV or more.

[0023] A dispersion according to one embodiment of the present invention comprises the hollow silica particles described above.

[0024] An optical film according to one embodiment of the present invention comprises the hollow silica particles described above. Effects of the invention

[0025] Hollow silica according to one aspect of the present invention has significantly excellent uniformity and characteristics of a silica wall material, and can have excellent utility in high-performance fine chemical and bio-material applications.

[0026] Hollow silica according to one aspect of the present invention has low refractive index, low dielectric constant, and excellent wear resistance, and has excellent uniformity of particle properties, so a coating film containing hollow silica can have optical properties of uniform low reflectance and low refractive index. Brief explanation of the drawing

[0027] Figures 1 and 2 show TEM images of hollow silica according to one embodiment. Figure 3 shows the nitrogen adsorption / desorption isotherm of hollow silica according to one embodiment. Figure 4 illustrates the pore distribution of hollow silica according to one embodiment. Specific details for implementing the invention

[0028] Unless otherwise defined, technical and scientific terms used in this specification have the meanings commonly understood by those skilled in the art to which this invention pertains, and descriptions of known functions and configurations that could unnecessarily obscure the essence of the invention are omitted in the following description and accompanying drawings.

[0029] The embodiments described in this specification may be modified in various different forms, and the technology according to one embodiment is not limited to the embodiments described below. Furthermore, the embodiment of one embodiment is provided to more fully explain the invention to those skilled in the art.

[0030] Additionally, the singular form used in the specification and the appended claims may be intended to include the plural form unless specifically indicated otherwise in the context.

[0031] Additionally, units used herein without special reference are based on weight, and, for example, units of % or ratio mean weight % or weight ratio, and weight % means the weight percentage of any one component of the total composition that occupies the composition, unless otherwise defined.

[0032] Additionally, the numerical ranges used in this specification include lower and upper limits and all values ​​within the range, increments logically derived from the form and width of the defined range, all of which are limited values, and all possible combinations of upper and lower limits of numerical ranges defined in different forms. Unless otherwise specifically defined in this specification, values ​​outside the numerical range that may occur due to experimental error or rounding are also included in the defined numerical range.

[0033] The term "comprising" in this specification is an open description equivalent to expressions such as "comprising," "containing," "having," or "characteristics," and does not exclude elements, materials, or processes not additionally enumerated. Furthermore, the term "substantially comprising" means that while the components described in the claims are included as essential components, non-essential components that do not substantially affect the functional effect may be additionally included.

[0034] Unless otherwise defined in this specification, the average particle size may be measured by a dynamic light scattering analyzer, and the average particle size refers to the volume-based average particle size.

[0035] The present invention will be described in detail below through each embodiment or example of the invention. It should be noted that each embodiment or example described in this specification is not limited to a single embodiment or example, but may also be combined with other embodiments or examples. Accordingly, the citation of claims in the patent claims is merely an example of an embodiment, and the technical concept of the present invention should not be interpreted as being limited only to a combination with the cited claims; rather, combinations with various claims are also included within the scope of the technical concept of the present invention.

[0036] A hollow silica particle according to one aspect of the present invention has Type IV adsorption / desorption characteristics in nitrogen isothermal adsorption / desorption, has a closing point at a relative pressure (P / P0) of 0.75 to 0.85, and is characterized by having a particle dispersion index of 1.7 or higher as indicated by the following formula 1.

[0037] [Equation 1]

[0038] D V / FWHM V

[0039] D in Equation 1 above V represents the volume-averaged particle size determined by dynamic light scattering analysis, and FWHMV represents the Full Width at Half Maximum of hollow silica particles in the volume particle size distribution graph.

[0040] The above-mentioned hollow silica particles, by incorporating a hollow structure, can possess low density and a high specific surface area, thereby offering excellent applicability as general thermal insulation and optical materials. Furthermore, by exhibiting Type IV nitrogen adsorption and desorption characteristics according to the IUPAC definition and having the particle dispersion index described above, they possess excellent properties for the adsorption, storage, and release of solutes, thus offering excellent applicability as supports or storage media such as drug delivery systems, catalyst supports, and adsorbents.

[0041] Specifically, the hollow silica particles may have a closing point at a relative pressure (P / P0) of 0.78 to 0.85, specifically 0.80 to 0.85. The closing point is a physical property representing the mesopore characteristics of the hollow silica particles and is related to the size distribution of the mesopores, the connectivity of the mesopores, and the surface characteristics of the mesopores. Therefore, the closing point can express pore characteristics that cannot be expressed by a combination of pore volume, pore size, and specific surface area of ​​the pores.

[0042] Specifically, the particle dispersion index represented by the above formula 1 may be 1.75 or higher, 1.8 or higher, or 1.85 or higher, and may be 10 or lower, 9 or lower, or 5 or lower, without limitation. Specifically, the particle dispersion index represented by the above formula 1 may be 1.7 to 10, 1.75 to 9, 1.8 to 5, or 1.85 to 5.

[0043] The BET specific surface area of ​​the above hollow silica particles is 40 to 120 m² 2 / g, 50 to 100 m 2 / g, 60 to 90 m 2 / g, specifically 65 to 85 m 2 It can be / g.

[0044] The pore volume of the above hollow silica particles is 0.3 to 0.7 cm 3 / g, 0.35 to 0.65 cm 3 / g, 0.4 to 0.6 cm 3 / g, specifically 0.45 to 0.55 cm 3 It can be / g.

[0045] The average pore diameter calculated by the nitrogen desorption standard BJH method of the hollow silica particles may be 15 to 35 nm, 18 to 32 nm, specifically 20 to 30 nm. The BET specific surface area, pore volume, and average pore size may be measured through BET analysis based on nitrogen adsorption and desorption. By including mesopores and a pore structure as described above, the hollow silica particles may be effective in adsorbing or storing solutes without deterioration of thermal insulation or optical properties due to the hollow structure. As a non-limiting example, a catalyst supported in the hollow of the hollow silica particles allows reactants to rapidly come into contact with the catalyst particles through low diffusion resistance, and the products generated through the catalytic reaction can be rapidly discharged to the outside, thereby maintaining excellent catalytic activity even at relatively high space velocities.

[0046] According to one embodiment, in a log-scale graph of pore diameter and pore volume by BJH (Barrett-Joyner-Halenda) of the hollow silica particles, a single peak may be present in the range of pore diameter from 2 to 50 nm. Specifically, in a graph plotted with the log-scale pore diameter (w) calculated by BJH in a nitrogen adsorption / desorption experiment of the hollow silica particles as the x-axis and the derivative of pore volume with respect to the log-scale pore diameter (dV / dlog(w)) as the y-axis, the hollow silica particles exhibit a single peak in the mesopore diameter range, i.e., the range of diameter from 2 to 50 nm. That is, the fact that there is a single peak in the graph of log(w) vs dV / dlog(w) implies that very uniform mesopores are developed in the silica walls.

[0047] According to one embodiment, the hollow silica particles are 50 to 100 m 2 BET specific surface area of ​​ / g and 0.4 to 0.6 cm 3 It can have a pore volume of / g.

[0048] According to one embodiment, the hollow silica particles may have a hollow dispersion index of 1.5 or higher, represented by Formula 2 below.

[0049] [Equation 2]

[0050] D h / FWHM h

[0051] D in Equation 2 above h represents the average diameter of the hollow obtained from the transmission electron microscope image, and FWHM h represents the maximum full width at half maximum in the hollow size distribution graph. Specifically, the average diameter (D) of the above hollow. h ) and FWHM h represents the average value of the hollow diameter obtained through TEM image analysis for 100 random particles and the FWHM obtained from the diameter distribution.

[0052] Specifically, the hollow dispersion index represented by the above formula 2 may be 1.6 or higher, 1.7 or higher, 1.8 or higher, 1.9 or higher, 2.0 or higher, 2.1 or higher, or 2.2 or higher, and may be, without limitation, 10 or lower, 9 or lower, 8 or lower, or 5 or lower. Specifically, the hollow dispersion index represented by the above formula 2 may be 1.5 to 10, 1.6 to 9, 1.8 to 8, 2.0 to 5, or 2.2 to 5.

[0053] As the particle dispersion index and hollow dispersion index satisfy 1.7 or higher and 1.5 or higher, preferably 1.8 or higher and 2.0 or higher, respectively, the hollow silica particles can have a uniform hollowness for each individual particle and, preferably, can have excellent utility in optical materials where the refractive index of a micro-region must be maintained uniformly over a large area.

[0054] The volume fraction of the hollow part relative to the total volume of the hollow silica particles may be 45 to 75%, 48 to 70%, specifically 50 to 65%.

[0055] The volume average diameter (D) of the above hollow silica particles V ) may be 50 to 150 nm, 55 to 130 nm, 58 to 120 nm, 60 to 100 nm, or 60 to 90 nm. In addition, the average diameter of the hollow (D h ) may be 40 to 100 nm, 45 to 95 nm, 50 to 90 nm, 55 to 90 nm, 60 to 85 nm, or 65 to 85 nm.

[0056] According to one embodiment, the volume average diameter (D V ) is 60 to 90 nm, and the average diameter of the hollow (D h ) can be 50 to 80 nm, and specifically, the volume average diameter (D V ) is 65 to 90 nm, and the average diameter of the hollow (D h) is 50 to 80 nm, or volume average diameter (D V ) is 70 to 85 nm, and the average diameter of the hollow (D h ) can be 55 to 75 nm.

[0057] According to one embodiment, the volume average particle size (D) of the hollow silica particles V ) and number average particle size (D n The ratio of ) (D V / D n ) can satisfy 1 to 1.3. The number average particle size (D) of the hollow silica particles above. n ) refers to the number average particle size calculated by dynamic light scattering analysis. The above ratio (D V / D n ) is an indicator representing the particle size dispersion of hollow silica particles; it is known that general hollow silica particles not only exhibit polydispersity but also have a non-uniform hollow dispersion index as described above. However, hollow silica particles according to one embodiment may have a particle size distribution close to monodispersity. Specifically, the above ratio (D V / D n ) can be 1 to 1.25 or 1 to 1.2.

[0058] According to one embodiment, the absolute value of the zeta potential of the hollow silica particles may be 40 mV or more. Specifically, the hollow silica particles may have a negative zeta potential, may have an absolute value of 45 mV or more or 50 mV or more, and may have an absolute value of 70 mV or less, without limitation.

[0059] Another aspect of the present invention provides a dispersion comprising hollow silica particles as described above. The dispersion may be a dispersion dispersed in a polar solvent, for example, an aqueous dispersion, an alcohol dispersion, or a dispersion dispersed in an organic solvent, and the aqueous dispersion may further comprise a solvent that is miscible with water.

[0060] The above-mentioned miscibility may be an alcohol-based solvent, an acetate-based solvent, a carboxylic acid-based solvent, a ketone-based solvent, an amine-based solvent, an amide-based solvent, or an ether-based solvent, and specifically, examples may include but are not limited to acetic acid, methanol, ethanol, isopropanol, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, butanediol, glycerol, diethoxyamine, ethylene acetate, dimethylformamide, formic acid, N-methylpyrrolidone, propylene glycol monomethyl ether acetate, etc.

[0061] Another aspect of the present invention provides an article comprising hollow silica particles as described above. The article may be any one of a drug delivery system, a catalyst, an adsorbent, a sensor, an optical material, a film, a thermal insulation agent, and a cosmetic. The article comprising the hollow silica particles has the hollow silica particles uniformly dispersed therein and can provide superior performance in terms of physical properties according to the required purpose.

[0062] In one embodiment, the article may be an optical film. Optical films require uniform and excellent optical properties (refractive index, light transmittance, reflectance, etc.). While conventional hollow silica particles are effective in improving optical properties, they have the disadvantage that the uniformity of optical properties is poor across the entire optical film, particularly in large areas, due to the poor uniformity of the physicochemical properties of the particles.

[0063] However, the optical film according to the present invention, by including the hollow silica particles of the present invention described above, can possess uniform and excellent optical properties over the entire film area. Specifically, as the hollow silica particles in the optical film possess uniform physical properties and are uniformly dispersed, optical properties such as refractive index can be uniform over a large area, thereby providing superior optical effects in optical films where uniformity is required. Furthermore, the uniform dispersion of hollow silica particles suppresses stress concentration within the film and improves durability against external forces, which can increase scratch resistance and impact resistance. In addition, due to the uniform hollow distribution of the optical film, it can possess superior mechanical and chemical properties compared to conventional optical films, such as excellent thermal insulation performance and photothermal safety.

[0064] Specifically, the optical film is not particularly limited as long as it controls light characteristics such as reflection, transmission, refraction, and dispersion. As a non-limiting example, the optical film may be an anti-reflective or anti-reflective film, a low refractive index film, a polarizing film, a prism film, a diffusion film, a phase difference film, a brightness enhancement film, a transmission control film, etc.

[0065] Examples and experimental examples are described below with specific examples. However, the examples and experimental examples described below are merely illustrative of some aspects, and the technology described in this specification is not limited thereto.

[0066] <Example 1>

[0067] 1) Preparation of the first solution

[0068] 4,273 g of pure water was introduced into a glass reactor equipped with a stirrer, and 71 g of sodium aluminate (Na2O 41 wt%, Al2O3 49 wt%) and 4 g of sodium hydroxide were added and mixed, and then heated and maintained at 60 ℃ to prepare the first solution.

[0069] 2) Preparation of the second solution

[0070] A second solution was prepared by mixing and stirring 17,165 g of pure water and 487 g of an aqueous sodium silicate solution (9.5 wt% Na2O, 29 wt% SiO2) in a separate container at room temperature (25±5℃).

[0071] 3) Preparation of hollow silica aqueous sol

[0072] A core particle aqueous sol was prepared by slowly adding 5,652 g of the second solution to the first solution, which was being maintained at a temperature, over a period of 4 hours. Subsequently, the core particle aqueous sol was 70 A silica aqueous sol was prepared by slowly adding 12,000 g of the second solution over 4 hours while heating and maintaining it to form a shell around the core particles. 910 g of hydrochloric acid (Samjeon Chemical, 36%) was added to the silica aqueous sol and stirred for 1 hour, followed by aging for 24 hours to prepare a hollow silica aqueous sol having pores inside the particles.

[0073] 4) Preparation of hollow silica dispersion

[0074] Next, the solution was concentrated to 4,200 g using an ultrafiltration membrane with a fractional molecular weight of 300,000 Daltons, and impurities were removed by repeating the dilution and concentration process with pure water to obtain a concentrated hollow silica aqueous sol with an electrical conductivity of 68 μs / cm. Diisopropylamine was added to the concentrated hollow silica aqueous sol to adjust the pH to 11, and the solution was placed in a high-pressure reactor. Hydrothermal synthesis treatment was performed at 160°C for 6 hours to form a dense shell with increased density. Subsequently, a hollow silica dispersion containing dispersed hollow silica particles was prepared by repeatedly concentrating and diluting the solution using an ultrafiltration membrane with a fractional molecular weight of 300,000 Daltons to remove impurities.

[0075] <Example 2>

[0076] In the above Example 1, a hollow silica dispersion was prepared in the same manner as in Example 1, except that in the 1) first solution preparation step, 5,402 g of pure water, 90 g of sodium aluminate, and 5 g of sodium hydroxide were mixed, and in the 2) second solution preparation step, 16,036 g of pure water and 455 g of an aqueous sodium silicate solution were added.

[0077] <Example 3>

[0078] In the above Example 1, a hollow silica dispersion was prepared in the same manner as in Example 1, except that in the 1) first solution preparation step, 3,604 g of pure water, 60 g of sodium aluminate, and 3 g of sodium hydroxide were mixed, and in the 2) second solution preparation step, 17,834 g of pure water and 506 g of an aqueous sodium silicate solution were added.

[0079] <Example 4>

[0080] In the above Example 1, a hollow silica dispersion was prepared in the same manner as in Example 1, except that in the 1) first solution preparation step and the 3) hollow silica aqueous sol preparation step, the temperature of the first solution was heated and maintained at 70°C, and the core particle aqueous sol in the 3) hollow silica aqueous sol preparation step was heated and maintained at 80°C.

[0081] <Comparative Example 1>

[0082] In the above Example 1, a hollow silica dispersion was prepared in the same manner as in Example 1, except that in the S3) step of preparing a hollow silica aqueous sol, a mixture in which a second solution was added at once to a first solution that was heated and maintained at 98°C was heated and maintained to prepare a silica aqueous sol.

[0083] <Comparative Example 2>

[0084] In the above Example 1, a hollow silica dispersion was prepared in the same manner as in Example 1, except that in the S3) step of preparing a hollow silica aqueous sol, a mixture in which a second solution was added at once to a first solution that was heated and maintained at 70°C was heated and maintained to prepare a silica aqueous sol.

[0085] <중공 실리카 입자 평가>

[0086] (Experimental Example 1) Measurement of Hollow Size

[0087] As shown in FIGS. 1 and 2, transmission electron microscope images of hollow silica particles were obtained, and then the diameters of the hollows of 100 randomly selected hollow silica particles were measured to determine the average hollow diameter and the FWHM in the hollow size distribution graph. h ...was measured, and the results were recorded in Table 1 below.

[0088] (Experimental Example 2) Dynamic Light Scattering (DLS)

[0089] Dynamic light scattering analysis was performed using a light scattering spectrometer (Litesizer DLS700, Anton Paar) equipped with a 658 nm wavelength semiconductor laser of a laser Doppler system. After replacing the solvent with ethanol from water, the concentration of hollow silica particles in the dispersion was adjusted to 0.1 wt% and used as the analytical sample. Scattered light was detected by a detector (Avalanche photodiode, APD) positioned at 90° to the incident light source, and the particle distribution was calculated using the CONTIN routine. The volume-averaged particle size (D) of the hollow silica particles calculated in Table 1 below V ), number average particle size (D n ), FWHM V and zeta potential values ​​were recorded.

[0090] (Experimental Example 3) Analysis of Pore Characteristics

[0091] Nitrogen adsorption experiments were performed using 3Flex (Micromeritics) to determine the specific surface area and pore structure of hollow silica particles. Prior to nitrogen adsorption analysis, the sample was 150 After pretreatment for 8 hours under vacuum, nitrogen adsorption and desorption were performed to calculate the BET (Brunauer-Emmett-Teller) specific surface area, pore volume, and average pore size (diameter), and the results are listed in Table 1 below. The nitrogen adsorption-desorption BET isotherms are plotted in Figure 3, and the pore distribution map is plotted in Figure 4.

[0092]

[0093] Referring to Table 1 above, it was confirmed that the hollow silica particles in the hollow silica dispersion according to the example exhibit Type IV behavior in nitrogen isothermal adsorption / desorption, and have a closing point at a relative pressure of at least 0.78 and at most 0.83, and simultaneously D V / FWHM V It was confirmed that the value is 2 or higher, specifically 2.5 or higher. For example, referring to Fig. 3, the hollow silica of Example 1 was found to have a closing point at a relative pressure of 0.81 and exhibited typical Type IV BET adsorption-desorption behavior. The above results imply that the hollow silica according to Example 1 has very uniform mesopores, but the pore opening is narrower than the internal pores, suggesting that material diffusion is not easy. Accordingly, even if the hollow silica according to the example forms a composition together with a polymer forming a continuous phase and is manufactured into an article, the hollow structure can be preserved very well within the article, thereby exhibiting significant effects due to the hollow structure.

[0094] In addition, in the analysis of the pore characteristics above, the average pore diameter of the hollow silica particles according to the example was confirmed to be 25.7 nm to 33.2 nm and the average pore volume was 0.47 to 0.54 cm³ / g, and the average pore diameter of the hollow silica particles according to the comparative example was 29.4 nm to 31.2 nm and the average pore volume was 0.62 to 0.89 cm³ / g.

[0095] In addition, in the analysis of the pore characteristics above, only a single peak located in the range of pore diameters from 25 nm to 40 nm was observed in the graph of the differential value of volume relative to the pore diameter on a log scale due to BJH of the hollow silica particles according to the example. For example, referring to Fig. 4, the hollow silica of Example 1 was shown to have a single peak at approximately 31 nm. On the other hand, for the hollow silica according to Comparative Examples 1 and 2, a peak located in the range of pore diameters from 10 nm to 20 nm and a peak located in the range of 20 nm to 35 nm were observed simultaneously.

[0096] The above results suggest that the hollow silica according to the example has uniform colloidal, hollow, and pore characteristics.

[0097] <코팅막 평가>

[0098] Low-reflection coating solutions containing the hollow silica dispersions prepared in the above examples and comparative examples, respectively, were prepared, and the physical properties of the coating films prepared from the coating solutions were evaluated.

[0099] Specifically, a low-reflection coating solution with a solid content of 3% by weight was prepared by mixing 60g of a siloxane-based resin diluted in propylene glycol methyl ether to a solid content concentration of 50% by weight, 90g of a concentrated hollow silica aqueous sol according to the example and comparative example dispersed in propylene glycol methyl ether to a concentration of 0.3% by weight, and 850g of propylene glycol methyl ether. After preparing a coating film using the method of the following test example, the physical properties were evaluated.

[0100] First, an anti-reflective coating solution is applied to the slide glass (LK LAB KOREA, microscope slides) using the spin coating method, and 120 A specimen with an anti-reflective coating film of 20 cm in width, 20 cm in length, and 100 nm in thickness was obtained by performing heat curing at a temperature of 30 minutes.

[0101] Reflectance, haze, transmittance, and refractive index were measured at 10 random locations on the prepared specimens, respectively, and the mean and standard deviation were calculated. Reflectance was measured using a KONICA MINOLTA CM-3600A SPECTROPHOTOMETER, while haze and transmittance were measured using a Murakami Color Research Laboratory HM-150 HAZE METER. Separately, the refractive index was measured using an ellipsometer after forming a 1-micron thick coating film on a silicon wafer, and the evaluation results are listed in Table 2 below.

[0102]

[0103] Referring to Table 2 above, the coating film containing hollow silica according to the example showed good results in reflectance, haze, transmittance, and refractive index, and in particular, it was confirmed to have uniform optical properties over the entire area. On the other hand, Comparative Examples 1 and 2 were found to have non-uniform optical properties over the entire area.

Claims

Claim 1 Hollow silica particles characterized by having Type IV adsorption / desorption characteristics in nitrogen isothermal adsorption / desorption, having a closing point at a relative pressure of 0.75 to 0.85, and having a particle dispersion index represented by the following Equation 1 of 1.8 to 10. [Equation 1]D V / FWHM V (D in Equation 1 above V represents the volume-averaged particle size determined by dynamic light scattering analysis, and FWHM V represents the maximum full width at half maximum of hollow silica particles in the volumetric particle size distribution graph. Claim 2 In claim 1, the hollow silica particles are hollow silica particles having a hollow dispersion index represented by the following Formula 2 of 1.5 or higher. [Formula 2]D h / FWHM h (D in Equation 2 above h represents the average diameter of the hollow obtained from the transmission electron microscope image, and FWHM h (represents the full width at half maximum in the hollow size distribution graph) Claim 3 In claim 1, the volume average particle size (D) of the hollow silica particles V ) and number average particle size (D n The ratio of ) (D V / D n ) is a hollow silica particle satisfying 1 to 1.

3. Claim 4 In claim 1, the BET specific surface area of ​​the hollow silica particles is 50 to 100 m² 2 / g and the pore volume is 0.4 to 0.6 cm³ 3 Hollow silica particles with a phosphorus content of 1 / g. Claim 5 A hollow silica particle according to claim 1, wherein the average pore diameter calculated by the nitrogen desorption standard BJH method of the hollow silica particle is 20 to 30 nm. Claim 6 In claim 1, the hollow silica particle having a single peak in the range of pore diameters from 2 to 50 nm in the graph of the differential value of pore volume with respect to the pore diameter on a log scale due to BJH of the hollow silica particle. Claim 7 In claim 1, the volume average particle size (D) of the hollow silica particles V ) is 60 to 90 nm, and the average diameter of the hollow (D h ) is a hollow silica particle with a length of 50 to 80 nm. Claim 8 A hollow silica particle according to claim 1, wherein the absolute value of the zeta potential of the hollow silica particle is 40 mV or more. Claim 9 A dispersion containing hollow silica particles according to any one of claims 1 to 8. Claim 10 An optical film comprising hollow silica particles according to any one of claims 1 to 8.

Images