Graphite-like carbon nitride having porous structure

Abstract

To provide graphite-like carbon nitride that brings about improved UV absorption property, and can show a desired color.SOLUTION: Graphite-like carbon nitride having a porous structure has at least one heptadine unit, and has a pore volume exceeding 0.0045 cm3 / g derived from a first type of pore having a specific pore diameter of 1nm or more and less than 15nm and derived from a second type pore having a specific pore diameter of 15nm or more and 50nm or less.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention mainly relates to graphitic carbon nitride having a porous structure, preferably graphitic carbon nitride having a porous structure for use as an ultraviolet (UVA and / or UVB) absorbing material in cosmetics.

Background Art

[0002] The UV protection effect is one of the important elements regarding cosmetics. Graphitic carbon nitride, which is an inorganic compound, is known to exhibit UV absorption characteristics. Several documents regarding graphitic carbon nitride have already been reported.

[0003] For example, CN103240121A, CN105126893A, and CN106423244A disclose carbon nitride materials, however, these documents do not mention the use of carbon nitride as an ultraviolet absorbing material in cosmetics.

[0004] Furthermore, makeup cosmetics are used to provide a desired color appearance, for example, a light color for easy color adjustment, to keratinous substances such as the skin, particularly the facial skin. In particular, a new environmentally friendly UV absorbing material for cosmetics is needed. Graphitic carbon nitride that can be used as an ultraviolet absorbing material and can provide a desired color to keratinous substances is not known.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Non-Patent Documents

[0006] [Non-Patent Document 1] Luhong Zhang et al. (ACS Omega, 2018, 3(11), pp. 15009 - 15017) [Non-Patent Document 2] Barbara Jurgens et al. (J. Am. Chem. Soc., 2003, 125(34), pp. 10288 - 10300) [Non-Patent Document 3] Bettina V. Lotsch et al. (Chem. Eur. J., 2007, 13(17), pp. 4969 - 4980) [Non-Patent Document 4] Nan Liu et al. (ACS Omega, 2020, 5, pp. 12557 - 12567) [Summary of the Invention] [Problems to be Solved by the Invention]

[0007] An object of the present invention is to provide graphitic carbon nitride having a porous structure that can provide UVA and / or B protection to keratinous materials, particularly human keratinous materials such as skin and keratin fibers such as hair. Another object of the present invention is to provide carbon nitride having a color variation that enables adjustment of the composition to a desired color tone for any application, for example, for cosmetic or paint products, or particularly as a filler in plastics. [Means for Solving the Problems]

[0008] The above object of the present invention can be achieved by graphitic carbon nitride having a porous structure, having at least one heptazine unit, derived from pores of a first type having a specific pore diameter of more than 1 nm and less than 15 nm, and derived from pores of a second type having a specific pore diameter of 15 nm or more and 50 nm or less, and having a pore volume of more than 0.0045 cm 3 / g.

[0009] Graphitic carbon nitride may contain at least one having a pore diameter in the range of 1.5 to 200 nm, preferably 2 to 150 nm, more preferably 3 to 100 nm, and even more preferably 5 to 80 nm.

[0010] Graphitic carbon nitride may have a specific surface area in the range of 5 to 300 m 2 / g, preferably 15 to 250 m 2 / g, more preferably 30 to 200 m 2 / g as determined by the BET method.

[0011] Graphitic carbon nitride may have a whiteness value in the range of -60 to 100, preferably -40 to 80.

[0012] Graphitic carbon nitride may have an onset absorption edge value in the range of 390 to 480 nm, preferably 395 to 450 nm.

[0013] Graphitic carbon nitride may have a pore volume of more than 0.0055 cm 3 / g derived from pores having a specific pore diameter in the range of 1.5 nm to 5 nm.

[0014] Graphitic carbon nitride may have a pore volume of more than 0.0045 cm 3 / g derived from pores having a specific pore diameter in the range of 15 nm to 50 nm.

[0015] The present invention also relates to a method for producing graphitic carbon nitride according to the present invention, comprising: i) preparing at least one precursor compound; and ii) heating the at least one precursor compound at 450 °C or higher for at least 1 minute.

[0016] The heating step ii) of the above method may be carried out in the presence of an oxygen-containing species, such as O2 (especially by an oxygen flux) and / or humidity.

[0017] ​The present invention also relates to the use of graphitic carbon nitride according to the invention as a paint activator, as a pigment, in particular as a filler for plastics, or as a cosmetic activator, in particular as a UV absorber.

[0018] The present invention also relates to a composition comprising graphitic carbon nitride according to the invention, water and / or at least one organic medium.

[0019] The present invention also relates to a composition comprising graphitic carbon nitride according to the invention, preferably a cosmetic composition for keratinous substances such as the skin, in particular a sunscreen composition.

[0020] The composition may not contain TiO2 or ZnO, or may contain TiO2 and / or ZnO in an amount of 5% by mass or less, more preferably 1% by mass or less, based on the total mass of the composition.

Brief Description of the Drawings

[0021]

Figure 1

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Figure 3B

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Figure 7

Mode for Carrying Out the Invention

[0022] As a result of intensive studies, the present inventors have surprisingly found that the new structure of graphitic carbon nitride can exhibit the appearance of a desired color and UV A and / or B absorption characteristics, and that it is very suitable for cosmetic applications, thus completing the present invention.

[0023] Accordingly, the present invention relates mainly to graphitic carbon nitride having a porous structure, having at least one heptazine unit, derived from pores of a first type having a specific pore diameter of more than 1 nm and less than 15 nm, and derived from pores of a second type having a specific pore diameter of 15 nm or more and 50 nm or less, and having a pore volume of more than 0.0045 cm 3 / g.

[0024] The graphitic carbon nitride according to the present invention provides improved UV A and / or B absorption characteristics and can exhibit the appearance of a desired color, for example, a light color for easy color adjustment, and is therefore very useful as a UV A and / or B absorber for various products, particularly cosmetics.

[0025] Hereinafter, the present invention will be described in detail.

[0026] [Graphitic carbon nitride] The present invention relates to graphitic carbon nitride having a porous structure, having at least one heptazine unit, derived from pores of a first type having a specific pore diameter of 1 nm or more and less than 15 nm, and 0.0045 cm 3 superior to / g of pore volume, and relates to graphitic carbon nitride.

[0027] Here, the term "graphitic" in graphitic carbon nitride means that the carbon nitride has a sheet graphite-like structure. Therefore, the graphitic carbon nitride of the present invention has a layered or sheet structure.

[0028] The graphitic carbon nitride of the present invention contains at least one heptazine unit. In the present specification, the heptazine unit means a hetero-condensed ring composed of three hetero rings composed of C atoms and N atoms, represented by C6N7. Therefore, the graphitic carbon nitride of the present invention has a monolayer structure based on heptazine. The graphitic carbon nitride of the present invention may contain at least one heptazine unit, at least one triazine unit, and combinations thereof. The presence of the heptazine unit can be determined by X-ray diffraction (XRD) analysis, Fourier transform infrared spectroscopy (FT-IR) analysis, and nuclear magnetic resonance spectroscopy (NMR) analysis.

[0029] The inventors of the present application generated graphitic carbon nitride by several heating processes, and surprisingly found by X-ray diffraction (XRD) analysis, Fourier transform infrared spectroscopy (FT-IR) analysis, and solid nuclear magnetic resonance spectroscopy (NMR) analysis that the graphitic carbon nitride of the present invention has a very unique structure having at least one heptazine unit.

[0030] In one embodiment of the present invention, the graphite-like carbon nitride of the present invention has a stack or laminated structure of layered graphite-like carbon nitride sheets. In other words, the graphite-like carbon nitride of the present invention may have a multi-layer sheet structure of graphite-like carbon nitride. The stack structure of the graphite-like carbon nitride sheets can be determined by X-ray diffraction (XRD) analysis and nuclear magnetic resonance spectroscopy (NMR) analysis.

[0031] The graphite-like carbon nitride of the present invention has a porous structure. More specifically, the graphite-like carbon nitride of the present invention has a nanoporous structure. The pores may exist between heptazine units and / or between the layers of the graphite-like carbon nitride sheets.

[0032] The heptazine unit is preferably represented by formula (I), its salts and its solvates, such as hydrates:

[0033] [Chemical formula]

[0034] (In formula (I), R 1 , R 2 , and R 3 are the same or different, i) a hydrogen atom, ii) a halogen atom, iii) an oxygen-containing group, such as a carboxy, nitro, or nitroso group, iv) a saturated or unsaturated, acyclic straight-chain or branched, and / or cyclic, aromatic or non-aromatic hydrocarbon chain containing 1 to 10 carbons, and potentially interrupted by one or more heteroatoms such as O, S, N, or N(O), v) hydroxy, vi) amino R 4 R 5 N- (wherein R 4 and R 5 are the same or different, a hydrogen atom, a (C1-C6) alkyl group or another monovalent heptazine group, preferably a monovalent heptazine group (II)

[0035] [Chemical formula]

[0036] represents, where R 1 and R 2 are as defined previously in this specification), vii) R 4 R 5 N(O)- (wherein R 4 and R 5 are the same or different and are as defined previously in this specification), and viii) R 4 -N(O)- (wherein R 4 is as defined previously in this specification) represents, -R 1 , R 2 , or R 3 at least one of the groups represents a hydroxyl group in v), more preferably, R1 represents a hydroxyl group in v), and R 2 and R 3 are the same or different, preferably the same, and represent a nitroso group selected from iii) vi) to viii), more preferably the nitroso group in viii), - One or more nitrogens in the ring may be oxidized (N-oxide or N-OH) It is understood.

[0037] ii) The halogen may be selected from Cl and Br.

[0038] iii) The hydrocarbon chain may be saturated or unsaturated, preferably saturated, acyclic straight-chain or branched, preferably acyclic straight-chain hydrocarbon chain. iii) The hydrocarbon chain may contain 1 to 6, preferably 1 to 4 carbons. Thus, iii) the hydrocarbon chain may be a saturated acyclic straight-chain hydrocarbon chain containing 1 to 6, preferably 1 to 4 carbons, which may be interrupted by one or more heteroatoms such as O, S, N, or N(O).

[0039] More preferably, R 1 , R 2 , and R 3 are the same or different, and are i) hydrogen, v) hydroxy, vi) amino R 4 R 5 N-(wherein R 4 and R 5 are the same or different and represent a hydrogen atom or another monovalent heptazine group (II), and R 1 and R 2 are as defined hereinbefore), and viii) nitroso R 4 -N(O)-(wherein R 4 is as defined hereinbefore).

[0040] Preferably, at least one of the R 1 , R 2 , or R 3 groups represents a v) hydroxy group.

[0041] The graphitic carbon nitride of the present invention is solid at room temperature and is generally in powder form. The graphitic carbon nitride can be suspended in water and organic media, such as polar oils including diisopropyl sebacate. Without wishing to be bound by theory, the reason why the graphitic carbon nitride of the present invention can be suspended in both water and oil is thought to be that the graphitic carbon nitride contains functional groups including those generated by separation and / or cracking occurring at the ends of the sheets of graphitic carbon nitride and in the heptazine units, which can contribute to changes in the hydrophilicity and hydrophobicity of the surface of the graphitic carbon nitride.

[0042] The graphite-like carbon nitride according to the present invention may contain at least one pore having a pore diameter of more than 1.13 nm. Preferably, the graphite-like carbon nitride contains at least one pore having a diameter of 1.5 nm or more, more preferably 2 nm or more, more preferably 3 nm or more, still more preferably 5 nm or more, and particularly 10 nm or more. The upper limit of the pore diameter contained in the graphite-like carbon nitride is not particularly limited, but generally it is 500 nm or less, preferably 400 nm or less, more preferably 300 nm or less, still more preferably 200 nm or less.

[0043] The pore diameter contained in the graphite-like carbon nitride according to the present invention can be in the range of 1 to 500 nm, preferably 2 to 400 nm, more preferably 3 to 300 nm, still more preferably 5 to 200 nm.

[0044] The graphite-like carbon nitride according to the present invention has a specific surface area of 5 m 2 / g or more, preferably 15 m 2 / g or more, more preferably 30 m 2 / g or more as determined by the BET method, and can have a specific surface area of 300 m 2 / g or less, preferably 250 m 2 / g or less, more preferably 200 m 2 / g or less as determined by the BET method.

[0045] The graphite-like carbon nitride according to the present invention has a specific surface area in the range of 5 to 300 m 2 / g, preferably 15 to 250 m 2 / g, more preferably 30 to 200 m 2 / g as determined by the BET method.

[0046] In some embodiments of the present invention, the graphite-like carbon nitride according to the present invention has a specific surface area in the range of 40 to 200 m 2 / g, preferably 45 to 190 m 2 / g, more preferably 50 to 180 m 2 / g as determined by the BET method.

[0047] The graphitic carbon nitride according to the present invention is characterized by its porous structure, and in this porous structure, it has a large pore volume of pores having a specific pore diameter contained in two different pore diameter regions. The different pore diameter regions may include first-type pores having a specific pore diameter of 1 nm or more and less than 15 nm, and second-type pores having a specific pore diameter of 15 nm or more and 50 nm or less.

[0048] Specifically, the graphitic carbon nitride according to the present invention is characterized by its porous structure, and in this porous structure, it is derived from first-type pores having a specific pore diameter of 1 nm or more and less than 15 nm, and 0.0045 cm 3 / g or more of pore volume derived from second-type pores having a specific pore diameter of 15 nm or more and 50 nm or less. This means that the graphitic carbon nitride has a pore volume of more than 0.0045 cm 3 / g derived from first-type pores having a specific pore diameter of 1 nm or more and less than 15 nm, and the graphitic carbon nitride has a pore volume of more than 0.0045 cm 3 / g derived from second-type pores having a specific pore diameter of 15 nm or more and 50 nm or less.

[0049] In one embodiment, the graphitic carbon nitride according to the present invention has a pore volume of more than 0.0055 cm 3 / g derived from pores having a specific pore diameter in the range of 1.5 nm to 10 nm, preferably 1.5 nm to 5 nm. This may mean that the first-type pores have a specific pore diameter in the range of 1.5 nm to 10 nm, preferably 1.5 nm to 5 nm.

[0050] In another embodiment, the graphitic carbon nitride according to the present invention has a pore volume of more than 0.0055 cm 3 / g derived from pores having a specific pore diameter in the range of 1.5 nm to 5 nm, which can be the first-type pores.

[0051] In still another embodiment, the graphitic carbon nitride according to the present invention has a pore volume of more than 0.0045 cm 3It has a pore volume exceeding 0.0050 cm³ / g. This may mean that the second type of pores has a specific pore diameter in the range of 20 nm to 45 nm.

[0052] In yet another embodiment, the graphitic carbon nitride has a pore volume exceeding 0.0050 cm 3 ³ / g, preferably 0.0055 cm 3 ³ / g, more preferably 0.0060 cm 3 ³ / g.

[0053] In the present invention, the amount and specific surface area of the pores having the specific pore diameter of the graphitic carbon nitride can be determined by analyzing the pore size distribution plot obtained from the nitrogen adsorption - desorption isotherm measured using a surface area and porosity analyzer. The amount of the pores having the specific pore diameter contained in the graphitic carbon nitride can be determined by using the Barrett - Joyner - Halenda (BJH) method on the obtained pore size distribution plot. The specific surface area of the graphitic carbon nitride can be determined by using the Brunauer - Emmett - Teller (BET) method on the obtained pore size distribution plot.

[0054] The graphitic carbon nitride of the present invention can exhibit a light color for easy color adjustment, which is suitable and desirable for cosmetics. In a preferred embodiment of the present invention, the graphitic carbon nitride can exhibit white, which is valuable for use in place of ZnO in cosmetics.

[0055] The whiteness of the graphitic carbon nitride can be defined by a whiteness value. The whiteness value can be measured using a UV - vis diffuse reflectance spectrometer. The whiteness value of the graphitic carbon nitride can be in the range of - 60 to 100, preferably - 40 to 80. In a preferred embodiment of the present invention, the graphitic carbon nitride exhibits a whiteness value of - 30 or more. The higher the whiteness value, the whiter the appearance of the graphitic carbon nitride indicates.

[0056] The graphite-like carbon nitride of the present invention can exhibit UV A and / or B absorption characteristics. Generally, the graphite-like carbon nitride of the present invention can exhibit the characteristic of absorbing UV rays having a wavelength of less than 400 nm. Preferably, the graphite-like carbon nitride has an absorption effect on both the UV-B and UV-A ray regions. Here, the UV-B ray means a UV ray having a wavelength between 280 and 320 nm. Here, the UV-A ray means a UV ray having a wavelength between 320 and 400 nm.

[0057] The UV absorption characteristics of the graphite-like carbon nitride of the present invention can be represented by the starting absorption end value (nm). The starting absorption end value can be defined by the wavelength (nm) at the intersection of a straight line drawn to fit the region where the absorbance curve rapidly decreases from the short-wavelength side of the absorbance curve and a straight line drawn to fit the absorbance curve in a specific wavelength range between 500 and 650 nm where the absorbance curve becomes constantly low.

[0058] Example 3 in FIG. 4 shows an example of the starting absorption characteristic of 405 nm, which is the wavelength at the intersection of (1) a straight line drawn to fit the region where the absorbance curve rapidly decreases from the short-wavelength side of the absorbance curve and (2) a straight line drawn to fit the absorbance curve in a specific wavelength range between 500 and 650 nm where the absorbance curve becomes constantly low. The absorption curves in the ultraviolet and visible light ranges can be measured, for example, by ultraviolet-visible (UV-vis) diffuse reflection spectroscopy. The higher the starting absorption end value, the more it means that the graphite-like carbon nitride can block light rays of longer wavelengths.

[0059] The graphite-like carbon nitride of the present invention can have a starting absorption end value of 390 nm or more, preferably 395 nm or more. The graphite-like carbon nitride of the present invention can have a starting absorption end value of 480 nm or less, preferably 450 nm or less.

[0060] The graphite-like carbon nitride of the present invention can have a starting absorption end value in the range of 390 to 480 nm, preferably 395 to 450 nm.

[0061] The graphite-like carbon nitride of the present invention may or may not be surface-treated with a surface treatment agent. Preferably, the graphite-like carbon nitride is not surface-treated with a surface treatment agent.

[0062] Although not wishing to be bound by theory, it is believed that the graphite-like carbon nitride of the present invention has a characteristic porous structure that contributes to the color appearance of graphite-like carbon nitride suitable for cosmetics. It is presumed that there are cracks in the chemical bonds in the heptazine unit of the porous graphite-like carbon nitride of the present invention, for example, cracks in the chemical bonds between carbon atoms and nitrogen atoms. The cracks can cause a wider bandgap in the graphite-like carbon nitride, resulting in the characteristic color appearance of the graphite-like carbon nitride according to the present invention. Since the graphite-like carbon nitride of the present invention has a relatively large pore volume of pores, it is considered that there are a large number of cracks in the chemical bonds in the heptazine unit.

[0063] [Manufacturing method] The present invention also relates to a method for manufacturing the graphite-like carbon nitride of the present invention.

[0064] Specifically, the present invention also relates to a method for manufacturing the graphite-like carbon nitride of the present invention, comprising: i) a step of preparing at least one precursor compound; and ii) a step of heating the at least one precursor compound at 450 °C or higher for at least 1 minute The graphite-like carbon nitride can be prepared by heating at least one precursor compound of the graphite-like carbon nitride. One precursor compound may be used as a raw material for the graphite-like carbon nitride, or two or more precursor compounds may be used in combination.

[0065]

[0066] The precursor compound can be selected from, for example, urea, thiourea, melamine, guanidine, arginine, cyanamide, dicyandiamide, and their salts, and combinations thereof. Preferably, the precursor compound is selected from urea, melamine, guanidine, arginine, and their salts and combinations thereof, and particularly preferably from melamine, urea, and their salts and combinations thereof.

[0067] The salt of the precursor compound is not particularly limited, and examples thereof include salts with inorganic acids such as carboxylic acids and hydrochloric acid.

[0068] In a preferred embodiment of the present invention, in the preparation of graphitic carbon nitride, only one precursor compound is used as a raw material.

[0069] The temperature for heating at least one precursor compound is at least 450 °C. Preferably, the heating is carried out at 500 °C or higher, more preferably 525 °C or higher.

[0070] The time for heating at least one precursor compound is at least 1 minute. Preferably, the heating time is at least 10 minutes, more preferably at least 20 minutes, and / or within 30 hours, more preferably within 25 hours.

[0071] The heating of the precursor compound can be carried out in air, in a noble gas such as argon or helium, or in an inert gas such as nitrogen. In a preferred embodiment of the present invention, the heating of the precursor compound is carried out in air or in argon.

[0072] In a preferred embodiment, the heating process can be carried out in the presence of an oxygen-containing species as an oxidant, such as O2, humidity, O3, atomic O, and / or oxygen ions. Without wishing to be bound by theory, it is considered that more porous graphitic carbon nitride can be obtained when the heating is carried out in the presence of an oxygen-containing species. In a preferred embodiment, the heating is carried out in air, or in a noble gas or inert gas containing an oxygen-containing species.

[0073] In a preferred embodiment, in addition to oxygen in the air, the heating process is carried out in the presence of oxygen-containing species as oxidizing agents, such as O2, humidity, ozone O3, O atoms, and / or oxygen ions.

[0074] In a preferred embodiment, the heating process is carried out in the presence of O2, particularly an oxygen flux, and / or oxygen-containing species of humidity. The term "oxygen flux" may mean an oxygen flow herein.

[0075] Preferably, the oxidizing agent used during the heating step is gaseous.

[0076] According to one embodiment, the oxygen source is neither derived from permanganate nor from hydrogen peroxide.

[0077] In one embodiment of the present invention, the heating process includes at least two heating steps at the same or different temperatures. In other words, the heating process may include a post-heating step. Thus, in one embodiment, the heating process may include a first heating step of at least one precursor compound at 450 °C or higher for at least 1 minute, and then a second heating step of at least one precursor compound at 450 °C or higher for at least 1 minute. The temperature of the first heating step and the temperature of the second heating step may be the same or different, but generally, the temperature of the second heating step is equal to or higher than the temperature of the first heating step. The temperature and time of the first and second heating steps are as described above.

[0078] In one embodiment of the present invention, a cooling step exists between the heating steps. Thus, in one embodiment, the cooling step is included between the first heating step and the second heating step. The temperature of the cooling step is not particularly limited. For example, the temperature is cooled to room temperature (about 25 °C). The time of the cooling step is not particularly limited. For example, it is about 1 minute to 24 hours.

[0079] [Use] The present invention may relate to the use of graphitic carbon nitride of the present invention as a UV-A and / or UV-B absorber for protecting products from damage caused by UV-A and / or UV-B irradiation. For example, the UV-A and / or UV-B absorber of the present invention can be used in paints, coatings, and cosmetics.

[0080] The graphitic carbon nitride of the present invention can exhibit improved UV-A and / or UV-B absorption characteristics, so the use of the present invention can bring an improved protective effect to the products used. In addition, since the graphitic carbon nitride of the present invention can exhibit a color suitable for cosmetics, the use of the present invention can bring a desired coloring and an attractive appearance to the products.

[0081] [Composition] The present invention also relates to a composition containing the graphitic carbon nitride of the present invention.

[0082] Since the graphitic carbon nitride according to the present invention can be suspended in water and organic solvents, the present invention relates to a composition containing the graphitic carbon nitride according to the present invention and water and / or at least one organic medium. In this embodiment, the composition according to the present invention can be a suspension of graphitic carbon nitride in water and / or an organic medium.

[0083] Examples of the organic medium include monoalcohols such as C1-C6 monoalcohols such as ethanol and propanol; polyols such as C1-C6 polyols such as glycerin; and C1-C6 alkylene glycols such as ethylene glycol and propylene glycol; and mixtures thereof.

[0084] In addition, the composition according to the present invention is a cosmetic composition, particularly a cosmetic composition for keratinous substances such as skin. In a preferred embodiment, the composition according to the present invention is a sunscreen composition.

[0085] The composition according to the present invention preferably contains neither TiO2 nor ZnO. In another embodiment, the composition according to the present invention contains TiO2 and / or ZnO in an amount of 5% by mass or less, more preferably 1% by mass or less, based on the total mass of the composition. The graphite-like carbon nitride of the present invention can be used in the composition instead of TiO2 and ZnO, which are known as traditional inorganic UV blockers.

[0086] Since the graphite-like carbon nitride of the present invention can exhibit improved UV absorption characteristics, the composition of the present invention can exhibit an improved UV protection effect. In addition, since the graphite-like carbon nitride of the present invention can exhibit a color suitable for cosmetics, the cosmetic composition according to the present invention can provide a desired coloring and an attractive appearance to keratinous substances.

Examples

[0087] The present invention will be described in more detail by way of examples. However, these examples should not be construed as limiting the scope of the present invention.

[0088] [Preparation] Powdery graphite-like carbon nitride according to the present invention was prepared in Examples 1 to 5 below, and Comparative Examples 1 and 2.

[0089] (Comparative Example 1) Various masses of melamine powder in the range of 3 g to 5 g were heated at 550° C. for 2 hours in air as a precursor compound, and then mixed together to obtain graphite-like carbon nitride according to Comparative Example 1.

[0090] (Comparative Example 2) 3 g of melamine powder was heated at 600° C. for 8 hours in an argon gas stream (200 mL / min) as a precursor compound to obtain graphite-like carbon nitride according to the comparative example.

[0091] (Example 1) 5 g of melamine powder was used as a precursor compound and heated at 550 °C for 2 hours in air, and then at 600 °C for 16 hours in air to obtain graphite-like carbon nitride according to Example 1.

[0092] (Example 2) 5 g of melamine powder was used as a precursor compound and heated at 550 °C for 2 hours in air, and then at 600 °C for 19 hours in air to obtain graphite-like carbon nitride according to Example 2.

[0093] (Example 3) Urea powder with various masses in the range of 1 g to 10 g was used as a precursor compound and heated at 600 - 605 °C for 2 hours in air, and then mixed together to obtain graphite-like carbon nitride according to Example 3.

[0094] (Example 4) 10 g of urea powder was used as a precursor compound and heated at 550 °C for 1 hour in air, and then at 600 °C for 30 minutes in air to obtain graphite-like carbon nitride according to Example 4.

[0095] (Example 5) 10 g of urea powder was used as a precursor compound and heated at 600 °C for 2 hours in air, cooled to room temperature, and then heated at 600 °C for 1 hour in air to obtain graphite-like carbon nitride according to Example 5.

[0096] [Evaluation] (Morphology, crystal structure, and chemical structure) The morphology of each of the graphitic carbon nitrides was observed using a field emission scanning electron microscope (FE-SEM). The crystal structure of each of the graphitic carbon nitrides was identified using X-ray diffraction (XRD) analysis. In the XRD pattern, according to Luhong Zhang et al. (ACS Omega, 2018, 3(11), pp. 15009 - 15017), the peak at 13° was assigned to the (100) of the graphitic carbon nitride having heptazine units; the peak at 27° was assigned to the (002) plane of the c-axis in the stacked sheets of the graphitic carbon nitride. The appearance of these peaks indicates the presence of the stacked sheets of the graphitic carbon nitride having heptazine units.

[0097] The chemical structure of each of the graphitic carbon nitrides was identified by solid-state nuclear magnetic resonance spectroscopy (NMR) and Fourier transform infrared spectroscopy (FT-IR) using an Avance 400 (Bruker Corporation). Solid NMR spectra were collected by cross-polarization / magic angle spinning (CP / MAS) and dipolar decoupling / magic angle spinning (DD / MAS) methods.

[0098] Figure 1 shows the representative (a) 13 13C CP / MAS spectrum, (b) 13 13C DD / MAS spectrum, and (c) 15 15N CP MAS NMR spectrum of the graphitic carbon nitride according to Example 3.

[0099] As shown in Figure 1 13The peaks appearing at (C1) and (C2) in both the C CP / MAS and DD / MAS NMR spectra were assigned, respectively, according to Barbara Jurgens et al. (J. Am. Chem. Soc., 2003, 125(34), pp. 10288 - 10300) and Bettina V. Lotsch et al. (Chem. Eur. J., 2007, 13(17), pp. 4969 - 4980), to the carbon atoms adjacent to the two pyridine nitrogen atoms and the nitrogen atom of the amino group of the heptazine unit containing graphitic carbon nitride at (C1), and to the carbon atoms adjacent to the two pyridine nitrogen atoms and the central nitrogen atom of the heptazine unit at (C2). 13 For the C CP / MAS method, the sensitivity was enhanced by utilizing magnetization transfer from protons. The sensitivity is higher for carbon and nitrogen atoms located closer to the protons. Semi - quantitative analysis was 13 For the C DD / MAS method, it was carried out by setting the pulse delay time to 4000 s. As shown in Figure 2 15 The peaks appearing at (N1), (N2), (N3), and (N4) in the N CP / MAS spectrum were assigned, respectively, to (N1) the pyridine nitrogen atom, (N2) the central nitrogen atom of the heptazine unit, (N3) the secondary amino group bridging the heptazine units, and (N4) the nitrogen atom of the primary amino group at the end of the heptazine unit containing graphitic carbon nitride. The IR spectrum was obtained using the attenuated total reflection (ATR) method. The peak assigned to the heptazine unit appears at 804 cm -1 which is at a higher wavenumber than the wavenumbers of the triazine units (814 cm -1 for melamine and 808 cm -1 ) according to Nan Liu et al. (ACS Omega, 2020, 5, pp. 12557 - 12567).

[0100] According to these analyses of the graphitic carbon nitride according to Example 4, all the appearing peaks were assigned to the C and N atoms of the heptazine unit. Therefore, it was confirmed that the graphitic carbon nitride of the present invention has a multilayer sheet of graphitic carbon nitride having a heptazine unit. The same results were obtained for the graphitic carbon nitride according to other examples.

[0101] Figure 2 shows a typical XRD pattern of the graphitic carbon nitride according to Example 3. Peaks assigned to (100) and (002) planes of the graphitic carbon nitride having a heptazine unit appeared, indicating the presence of a stacked sheet of the graphitic carbon nitride having a heptazine unit. The same results were obtained for the graphitic carbon nitride according to other examples.

[0102] (UV Absorption Characteristics and Whiteness Value) The light absorption performance of each of the graphitic carbon nitrides in the wavelength range of ultraviolet and visible light was evaluated using ultraviolet-visible (UV-vis) diffuse reflectance spectroscopy (UV2500PC, Shimadzu Corporation) equipped with an integrating sphere.

[0103] Using a UV-vis spectrophotometer (V750, Jasco Inc.) equipped with an integrating sphere, the UV-vis absorption spectra of liquids in which 0.01 mass% of each of the graphitic carbon nitrides was suspended in a fine quartz cell (two transparent sides, 2 mm (optical path length) × 10 mm × H45 mm, Tokyo Garasu Kikai Co., Ltd.) were collected. Water / isopropanol (99:1 by mass), water / PG (volume ratio: 50:50), or water alone was used as the suspension medium. The starting absorption edge was estimated from the UV-vis diffuse reflectance spectrum of each sample.

[0104] The white value was also evaluated from the UV-vis diffuse reflection spectrum of each sample. The white value was calculated using light source D65 as the standard light source, setting the viewing angle to 10°, and using the software of Shimadzu Corporation installed in the device. A BaSO4 standard white plate was used as a reference.

[0105] Using a UV-2000S in-vitro sunscreen analyzer (Labsphere, Inc.) equipped with an integrating sphere, the diffuse transmittance in the wavelength range of 250 nm to 450 nm was measured with a polymethyl methacrylate (PMMA) (50 mm × 50 mm, Helioplate HD6; Helioscreen) plate. The powdered sample of graphitic carbon nitride was dispersed in water containing (a) diisopropyl sebacate and (b) hydroxyethyl cellulose. Then, 30 mg of the dispersion was applied to the PMMA plate and the solvent was dried.

[0106] (Porosity and specific surface area) The porosity and specific surface area of each of the graphitic carbon nitrides were evaluated using nitrogen adsorption-desorption isotherms. The sample was introduced into a quartz tube. In the pretreatment step, the tube was evacuated at 423 K for 5 hours using a vacuum degassing device. Then, the tube was cooled to room temperature and purged with helium gas. Then, the tube was connected to a surface area and porosity analyzer. The tube was evacuated and cooled to 77 K, and then nitrogen was introduced into the tube stepwise to collect the adsorption-desorption isotherm. The porosity was evaluated by the Barrett-Joyner-Halenda (BJH) pore size distribution plot obtained from the adsorption curve of the adsorption-desorption isotherm. The specific surface area was determined from the adsorption isotherm using the Brunauer-Emmett-Teller (BET) theory.

[0107] The BJH plots obtained according to Examples 1 to 5 and Comparative Examples 1 and 2 are shown in FIGS. 3(A) and 3(B). As can be seen from these BJH plots, characteristic structures were confirmed.

[0108] The graphitic carbon nitride according to Comparative Example 1 was 0.00035 cm 3 g-1 nm -1 ~0.0018 cm 3 g -1 nm -1 had pores with a diameter size in the range of 2 nm to 50 nm and having a pore volume in the range of

[0109] Graphitic carbon nitride according to Comparative Example 2 had pores with a diameter size in the range of 4 nm to 59 nm and having a pore volume in the range of up to 0.0019 cm 3 g -1 nm -1 Graphitic carbon nitride according to Example 1 had pores with a diameter size in the range of 2 nm to 50 nm and having a pore volume in the range of 0.0028 cm

[0110] Graphitic carbon nitride according to Example 1 had pores with a diameter size in the range of 2 nm to 50 nm and having a pore volume in the range of 0.0028 cm 3 g -1 nm -1 ~0.0068 cm 3 g -1 nm -1 In particular, the volumes of pores having a diameter size of about 2 nm, about 3 nm, and about 20 nm were 0.0064 cm 3 g -1 nm -1 , 0.0068 cm 3 g -1 nm -1 , and 0.0061 cm 3 g -1 nm -1 respectively.

[0111] Graphitic carbon nitride according to Example 2 had pores with a diameter size in the range of 2 nm to 50 nm and having a pore volume in the range of 0.0021 cm 3 g -1 nm -1 ~0.0074 cm 3 g -1 nm -1 In particular, the volumes of pores having a diameter size of about 3 nm, about 4 nm, and about 44 nm were 0.0074 cm 3 g -1 nm -1 , 0.0057 cm 3 g-1 nm -1 and 0.0049 cm 3 g -1 nm -1 in size.

[0112] The graphite-like carbon nitride according to Example 3 had pore volumes in the range of 0.0025 cm 3 g -1 nm -1 to 0.0225 cm 3 g -1 nm -1 and contained pores with diameter sizes in the range of 2 nm to 38 nm.

[0113] The graphite-like carbon nitride according to Example 4 had pore volumes in the range of 0.0021 cm 3 g -1 nm -1 to 0.0066 cm 3 g -1 nm -1 and contained pores with diameter sizes in the range of 1 nm to 44 nm. In particular, the volumes of pores with diameter sizes of about 3 nm and about 28 nm were 0.058 cm 3 g -1 nm -1 and 0.0066 cm 3 g -1 nm -1 in size, respectively.

[0114] The graphite-like carbon nitride according to Example 5 had pore volumes in the range of 0.005 cm 3 g -1 nm -1 to 0.0176 cm 3 g -1 nm -1 and contained pores with diameter sizes in the range of 2 nm to 44 nm.

[0115] Therefore, the graphite-like carbon nitride according to each of Examples 1 to 5 was derived from first-type pores having a specific pore diameter of 1 nm or more and less than 15 nm, and 0.0045 cm from second-type pores having a specific pore diameter of 15 nm or more and 50 nm or less 3It had a characteristic porous structure with a pore volume of over / g.

[0116] Also, the results are summarized in Table 1 below.

[0117]

Table 1

[0118] Table 1 shows that the graphite-like carbon nitride having a preferable white value has an onset absorption edge value of less than 443 nm and a specific surface area of over 12.

[0119] (Comparison of UV absorption characteristics) The absorption spectra obtained by measuring the UV-vis diffuse reflectance of the as-synthesized graphite-like carbon nitride according to Examples 1 to 3 are shown in FIG. 4 as a representative example. All the powder samples showed absorption in the UV wavelength range of less than 400 nm.

[0120] The absorption spectra of the liquids in which 0.01 mass% of the graphite-like carbon nitride according to Example 3 was suspended in water / isopropanol (99:1) and water / propylene glycol (50:50) are shown in FIG. 5 as a representative example. All these suspensions showed absorption in the UV wavelength range of less than 400 nm.

[0121] Suspended in an oil-based medium and then applied to a polymethyl methacrylate (PMMA) plate for sunscreen evaluation, the diffuse transmittance of the graphitic carbon nitride according to Example 3 in the wavelength range of 250 nm to 450 nm was compared with the diffuse transmittance of TiO2 (average primary particle size: 15 nm) and ZnO (average primary particle size: 20 nm), which are generally used as inorganic UV blockers. Each of the samples was dispersed in diisopropyl sebacate to obtain a suspension containing 3% by mass of graphitic carbon nitride. Then, 30 mg of the suspension was applied to a polymethyl methacrylate (PMMA) plate (50 mm × 50 mm, Helioplate HD6; Helioscreen), and the diffuse transmittance in the wavelength range of 250 nm to 450 nm was measured using a UV-2000S in-vitro sunscreen analyzer (Labsphere, Inc.). The results are shown in Fig. 7. As can be seen from Fig. 7, it is clear that the graphitic carbon nitride of the present invention was able to exhibit higher absorption characteristics than TiO2 and ZnO in the UV wavelength region of less than 400 nm.

[0122] Suspended in an aqueous medium and then applied to a PMMA plate for sunscreen evaluation, the diffuse transmittance of the graphitic carbon nitride according to Example 3 in the wavelength region of 250 nm to 450 nm also exhibited UV absorption characteristics. The sample was dispersed in water containing 1% by mass of hydroxyethyl cellulose to obtain a suspension containing 1% by mass of graphitic carbon nitride. Then, 30 mg of the suspension was applied to a PMMA plate (50 mm × 50 mm, Helioplate HD6; Helioscreen), then dried for a while, and the diffuse transmittance in the wavelength range of 250 nm to 450 nm was measured using a UV-2000S in-vitro sunscreen analyzer (Labsphere, Inc.). The results are shown in Fig. 8. As can be seen from Fig. 8, it is clear that the graphitic carbon nitride of the present invention can exhibit absorption characteristics in the UV wavelength region of less than 400 nm.

[0123] Therefore, it can be concluded that the graphite-like carbon nitride of the present invention brings about improved UV absorption characteristics and can exhibit a desired color particularly in cosmetic applications, and thus is very useful as a UV absorber for various products, particularly cosmetics.

Claims

1. Graphitic carbon nitride having a porous structure, having at least one heptazine unit, derived from pores of a first type having a specific pore diameter of 1 nm or more and less than 15 nm, and 0.0045 cm 3 / g or more of pore volume, graphitic carbon nitride.

2. Graphitic carbon nitride according to claim 1, comprising at least one having a pore diameter in the range of 1 to 500 nm, preferably 2 to 400 nm, more preferably 3 to 300 nm, and even more preferably 5 to 200 nm.

3. Determined by the BET method, 5 to 300 m 2 / g, preferably 15 to 250 m 2 / g, more preferably 30 to 200 m 2 / g, the graphitic carbon nitride according to claim 1 or 2 having a specific surface area in the range of

4. Graphitic carbon nitride according to any one of claims 1 to 3, having a whiteness value in the range of -60 to 100, preferably -40 to 80.

5. Graphitic carbon nitride according to any one of claims 1 to 4, having an onset absorption edge value in the range of 390 to 480 nm, preferably 395 to 450 nm.

6. Pore volume exceeding 0.0055 cm 3 / g derived from pores having a specific pore diameter in the range of 1.5 nm to 5 nm, the graphitic carbon nitride according to any one of claims 1 to 5. 3 / g, the graphitic carbon nitride according to any one of claims 1 to 5.

7. Graphitic carbon nitride according to any one of claims 1 to 6, having a pore volume of more than 0.0045 cm 3 / g derived from pores having a specific pore diameter in the range of 20 nm to 45 nm. 3 / g derived from pores having a specific pore diameter in the range of 20 nm to 45 nm.

8. A method for producing graphitic carbon nitride according to any one of claims 1 to 7, comprising: i) preparing at least one precursor compound; and ii) heating the at least one precursor compound at 450 °C or higher for at least 1 minute. A method comprising the above steps.

9. The step of ii) heating is carried out in the presence of an oxygen-containing species, such as O 2 , humidity, O 3 , O atoms, and / or oxygen ions; preferably, the oxidizing agent used during the heating step is gaseous; more preferably, the oxygen-containing species is not derived from permanganate or hydrogen peroxide, the method according to claim 8.

10. Use of graphitic carbon nitride according to any one of claims 1 to 7 as a paint activator, as a pigment, especially as a filler for plastics, or as a cosmetic activator.

11. Use of graphitic carbon nitride according to any one of claims 1 to 7 as a UV absorber.

12. A composition comprising graphitic carbon nitride according to any one of claims 1 to 7, water, and / or at least one organic medium.

13. A composition comprising graphitic carbon nitride according to any one of claims 1 to 7, preferably a cosmetic composition for keratinous substances such as skin.

14. The composition according to claim 13, which is a sunscreen composition.

15. TiO 2 containing neither TiO nor ZnO, or containing TiO 2 and / or ZnO in an amount of 5% by mass or less, more preferably 1% by mass or less, based on the total mass of the composition, the composition according to claim 13 or 14.

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