Graphitic carbon nitride with porous structures

Abstract

The present invention mainly relates to a graphitic carbon nitride with porous structures, wherein the graphitic carbon nitride has at least one heptazine unit, and has a pore volume greater than 0.0045 cm3 / g derived from first type of pores having a specific pore diameter of 1 nm or more and less than 15 nm and derived from second types of pores having a specific pore diameter of 15 nm or more and 50 nm or less. The graphitic carbon nitride can provide an improved UV absorption property and exhibit desired colors.

Description

[0001] DESCRIPTION

[0002] TITLE OF INVENTION

[0003] GRAPHITIC CARBON NITRIDE WITH POROUS STRUCTURES

[0004] TECHNICAL FIELD

[0005] The present invention mainly relates to a graphitic carbon nitride with porous structures, preferably a graphitic carbon nitride with porous structures for use an ultraviolent (UVA and / or UVB) absorbing material in cosmetic products.

[0006] BACKGROUND ART

[0007] A UV protecting effect is one of key factors for cosmetic products. Graphitic carbon nitride, which is an inorganic compound, is known for to exhibit UV absorbing properties. Some documents relating to graphitic carbon nitride have previously been reported.

[0008] For example, CN103240121A, CN105126893A, and CN 106423244 A disclose carbon nitride materials, however, these documents are silent about use of the carbon nitrides as ultraviolent absorbing materials in cosmetic products.

[0009] Moreover, Make-up cosmetic products are used in order to provide keratinous substances, such as skin, in particular facial skin, with a desired color appearance, such as pale color for easy color adjustment. New eco-friendly, UV absorbing materials are demanded, in particular for cosmetic products. No graphitic carbon nitride, which can be used as an ultraviolent absorbing material and can provide keratinous substances with a desired color, is known.

[0010] DISCLOSURE OF INVENTION

[0011] The objective of the present invention is to provide a graphitic carbon nitride with porous structures, which can provide the keratinous materials especially human keratin material, such as skin, and keratin fibers such as hair with UV A and / or B protection. Another object of the present invention is to provide carbon nitride having color variations that allow the composition to be adjusted to the desired tone for any application such as cosmetic or paint products or as fillers especially in plastics.

[0012] The above objective of the present invention can be achieved by a graphitic carbon nitride with porous structures, wherein the graphitic carbon nitride has at least one heptazine unit, and has a pore volume greater than 0.0045 cm3 / g derived from first type of pores having a specific pore diameter of 1 nm or more and less than 15 nm and derived from second types of pores having a specific pore diameter of 15 nm or more and 50 nm or less.

[0013] The graphitic carbon nitride may comprise at least one having a pore diameter ranging from 1.5 to 200 nm, preferably from 2 to 150 nm, more preferably from 3 to 100 nm, and even more preferably from 5 to 80 nm.

[0014] The graphitic carbon nitride may have a specific surface area determined by BET method ranging from 5 to 300 m2 / g, preferably 15 to 250 m2 / g, and more preferably 30 to 200 m2 / g. The graphitic carbon nitride may have a white value ranging from -60 to 100, preferably from -40 to 80.

[0015] The graphitic carbon nitride may have an onset absorption edge value ranging from 390 to 480 nm, preferably from 395 to 450 nm.

[0016] The graphitic carbon nitride may have a greater than 0.0055 cm3 / g pore volume derived from pores having a specific pore diameter in the range of 1.5 nm to 5 nm.

[0017] The graphitic carbon nitride may have a greater than 0.0045 cm3 / g pore volume derived from pores having a specific pore diameter in the range of 15 nm to 50 nm.

[0018] The present invention also relates to a process for manufacturing the 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 more for at least 1 minute.

[0019] The ii) heating in the process may be carried out in a presence of oxygen-containing species, such as O2 (especially with oxygen flux) and / or humidity.

[0020] The present invention also relates to a use of the graphitic carbon nitride according to the present invention as a paint active, as a pigment, as a filler especially of plastics or as a cosmetic active, in particular as a UV absorber.

[0021] The present invention also relates to a composition comprising the graphitic carbon nitride according to the present invention and water and / or at least one organic media.

[0022] The present invention also relates to a composition, preferably a cosmetic composition for keratinous substances, such as skin, in particular a sunscreen composition, comprising the graphitic carbon nitride according to the present invention.

[0023] The composition may not comprise TiCh or ZnO, or may comprise TiCh and / or ZnO in an amount of 5% by weight or less, more preferably 1% by weight or less, relative to the total weight of the composition.

[0024] BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 shows (a)13C CP / MAS spectra, (b)13C DD / MAS spectra, and (c)15N CP MAS NMR spectra obtained with the graphitic carbon nitride according to Example 3.

[0026] Figure 2 shows XRD patterns obtained with the graphitic carbon nitride according to Example 3.

[0027] Figures 3A and 3B show BJH plots obtained with the graphitic carbon nitride according to Comparative Examples 1 and 2 and Examples 1 to 5.

[0028] Figure 4 shows absorption spectra obtained via UV-vis diffuse reflectance measurement of the as-synthesized powder of graphitic carbon nitride according to Examples 1 to 3. Figure 5 shows absorption spectra of liquids suspended with 0.01 wt% of graphitic carbon nitride according to Example 3 in (a) water / isopropanol (99:1) and (b) water / propylene glycol (50:50).

[0029] Figure 6 shows absorption spectra obtained via UV-vis diffuse transmittance in the wavelength region from 250 nm to 450 nm of the graphitic carbon nitride according to Example 3 compared with TiCh (average primary particle size: 15 nm) and ZnO (average primary particle size: 20 nm).

[0030] Figure 7 shows UV-vis absorption spectrum obtained via diffuse transmittance measurement of the sample obtained by applying on PMMA plate 30 mg of the dispersion in water comprising 1% by weight of graphitic carbon nitride according to Example 3 and 1% by weight of hydroxyethyl cellulose was applied.

[0031] BEST MODE FOR CARRYING OUT THE INVENTION

[0032] After diligent research, the inventors have surprisingly found that a new structure of the graphitic carbon nitride can exhibit a desired color appearance as well as UV A and / or B absorbing property and that it is very suitable for cosmetic use, and thus completed the invention.

[0033] Thus, the present invention mainly relates to a graphitic carbon nitride with porous structures, wherein the graphitic carbon nitride has at least one heptazine unit and has a pore volume greater than 0.0045 cm3 / g derived from first type of pores having a specific pore diameter of 1 nm or more and less than 15 nm and derived from second types of pores having a specific pore diameter of 15 nm or more and 50 nm or less.

[0034] The graphitic carbon nitride according to the present invention can provide an improved UV A and / or B absorption property and exhibit a desired color appearance, such as pale color for easy color adjustment, and thus it is very useful as UV A and / or B absorbers for various products, in particular cosmetic products.

[0035] Hereafter, the present invention will be described in a detailed manner.

[0036] [Graphitic Carbon Nitride]

[0037] The present invention relates to a graphitic carbon nitride with porous structures, wherein the graphitic carbon nitride has at least one heptazine unit, and has a pore volume greater than 0.0045 cm3 / g derived from first type of pores having a specific pore diameter of 1 nm or more and less than 15 nm and derived from second types of pores having a specific pore diameter of 15 nm or more and 50 nm or less.

[0038] The term "graphitic" in graphitic carbon nitride here means that the carbon nitride has a sheet graphite -like structure. Thus, the graphitic carbon nitride of the present invention has a layered or a sheet structure.

[0039] The graphitic carbon nitride of the present invention comprises at least one heptazine unit.

[0040] In the present specification, the heptazine unit means a hetero-fused ring consisting of three hetero rings consisting of C atoms and N atoms, represented with CeN?. Thus, the graphitic carbon nitride of the present invention has a heptazine-based monolayer structure. The graphitic carbon nitride of the present invention may comprise at least one heptazine unit, at least one triazine unit, and a combination 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.

[0041] The inventors of the present application produced graphitic carbon nitrides with several heating process, and surprisingly discovered that the graphitic carbon nitrides of the present invention have the very unique structure with at least one heptazine unit via X-ray diffraction (XRD) analysis, Fourier transform infrared spectroscopy (FT-IR) analysis, and solid-state nuclear magnetic resonance spectroscopy (NMR) analysis.

[0042] In one embodiment of the present invention, the graphitic carbon nitride of the present invention has a stacked or laminated structure of the layered graphitic carbon nitride sheets. In other words, the graphitic carbon nitride of the present invention may have a multi-layered sheet structure of the graphitic carbon nitride. The stacked structure of the graphitic carbon nitride sheets can be determined by X-ray diffraction (XRD) analysis and nuclear magnetic resonance spectroscopy (NMR) analysis.

[0043] The graphitic carbon nitride of the present invention has a porous structure. More specifically, the graphitic carbon nitride of the present invention has a nano-porous structure. The pores may exist between heptazine units and / or between layers of the graphitic carbon nitride sheets.

[0044] The heptazine unit is preferably represented by formula (I), its salts and its solvates such as hydrates:

[0045] Formula (I) wherein, R1, R2, and R3, identical or different, represent: i) a hydrogen atom, ii) an halogen atom, iii) an oxygen-containing group as carboxy, nitro, or nitroso group, iv) a saturated or unsaturated, acyclic linear or branched, and / or cyclic, aromatic or nonaromatic, hydrocarbon chain containing from 1 to 10 carbon carbons, the said hydrocarbon chain being potentially interrupted by one or more heteroatom such as O, S, N or N(O); v) hydroxy, vi) amino R4R5N-, wherein R4and R5, identical or different, represent a hydrogen atom, (Ci-C6)alkyl group or another monovalent heptazine group, preferably a monovalent wherein R1and R2are as defined herein before; vii) R4R5N(O)-, wherein R4and R5, identical or different, are as defined herein before; and viii) R4-N(0)- or ; wherein R4is as defined herein before; it being understood that: at least one of radical R1, R2or R3represents v) a hydroxy group, more preferably R1 represents v) hydroxy group and R2and R3, identical or different, preferably identical, represent iii) nitroso group selected from vi) to viii), more preferably viii), and one or more nitrogen into the cycles can be oxidized (N-oxide, or N-OH).

[0046] The ii) halogen may be selected from Cl and Br.

[0047] The iii) hydrocarbon chain may be a saturated or unsaturated, preferably saturated, acyclic linear or branched, preferably acyclic linear, hydrocarbon chain. The iii) hydrocarbon chain may contain from 1 to 6, preferably 1 to 4 carbon carbons. Thus, the iii) hydrocarbon chain may be a saturated and acyclic linear hydrocarbon chain containing from 1 to 6, preferably 1 to 4 carbon carbons, which can be interrupted by one or more heteroatom such as O, S, N or N(O).

[0048] More preferably R1, R2, and R3, identical or different, represent an atom or group selected from i) a hydrogen, v) a hydroxy, vi) an amino R4R5N-, wherein R4and R5, identical or different, represent a hydrogen atom, or another monovalent heptazine group (II) wherein R1and R2are as defined herein before; and viii) nitroso R4-N(O)~ wherein R4is as defined herein before.

[0049] Preferably at least at least one of radical R1, R2or R3represents v) a hydroxy group.

[0050] The graphitic carbon nitride of the present invention is solid at room temperature, and in general in a powder form. The graphitic carbon nitride can be suspensible in water and in organic media, such as polar oils including diisopropyl sebacate. While not wishing to be bound by theory, it is believed that the reason why the graphitic carbon nitride of the present invention can be suspensible in both of water and oils is because the graphitic carbon nitride includes functional groups including amino groups at the edges of the sheets of graphitic carbon nitride and those produced by a discretization and / or a crack occurred in the heptazine units, which may contribute a change of hydrophilicity and hydrophobicity of the surface of the graphitic carbon nitride.

[0051] The graphitic carbon nitride according to the present invention may include at least one pore having a pore diameter greater than 1.13 nm. Preferably, the graphitic carbon nitride includes at least one pore having a diameter of 1.5 nm or more, more preferably 2 nm or more, and more preferably 3 nm or more, and even more preferably 5 nm or more, and in particular 10 nm or more. The upper limit of the pore diameter included in the graphitic carbon nitride is not particularly limited to, but in general is 500 nm or less, preferably 400 nm or less, more preferably 300 nm or less, even more preferably 200 nm or less.

[0052] The pore diameter included in the graphitic carbon nitride according to the present invention may range from 1 to 500 nm, preferably from 2 to 400 nm, more preferably from 3 to 300 nm, and even more preferably from 5 to 200 nm.

[0053] The graphitic carbon nitride according to the present invention may have a specific surface area determined by BET method of 5 m2 / g or more, preferably 15 m2 / g or more, and more preferably 30 m2 / g or more, and may have a specific surface area determined by BET method of 300 m2 / g or less, preferably 250 m2 / g or less, and more preferably 200 m2 / g or less.

[0054] The graphitic carbon nitride according to the present invention may have a specific surface area determined by BET method ranging from 5 to 300 m2 / g, preferably 15 to 250 m2 / g, and more preferably 30 to 200 m2 / g.

[0055] In some embodiments of the present invention, the graphitic carbon nitride according to the present invention may have a specific surface area determined by BET method ranging from 40 to 200 m2 / g, preferably 45 to 190 m2 / g, and more preferably 50 to 180 m2 / g.

[0056] The graphitic carbon nitride according to the present invention has a characteristic in its porous structure in that it has a large pore volume of pores having a specific pore diameter included in two different pore size regions. The different pore size regions can comprise the first type of pores having a specific pore diameter of 1 nm or more and less than 15 nm and the second types of pores having a specific pore diameter of 15 nm or more and 50 nm or less.

[0057] Specifically, the graphitic carbon nitride according to the present invention has a characteristic in its porous structure in that it a pore volume greater than 0.0045 cm3 / g derived from first type of pores having a specific pore diameter of 1 nm or more and less than 15 nm, and derived from second types of 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 greater than 0.0045 cm3 / g pore volume derived from the first type of 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 greater than 0.0045 cm3 / g derived from second type of pores having a specific pore diameter of 15 nm or more and 50 nm or less.

[0058] In one embodiment, the graphitic carbon nitride according to the present invention has a pore volume greater than 0.0055 cm3 / 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 can mean that the first type of pores have a specific pore diameter in the range of 1.5 nm to 10 nm, preferably 1.5 nm to 5 nm.

[0059] In another embodiment, the graphitic carbon nitride according to the present invention has a pore volume greater than 0.0055 cm3 / 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 of pores.

[0060] In yet another embodiment, the graphitic carbon nitride according to the present invention has a pore volume greater than 0.0045 cm3 / g derived from pores having a specific pore diameter in the range of 20 nm to 45 nm. This can mean that the second type of pores have a specific pore diameter in the range of 20 nm to 45 nm. In yet another embodiment, the graphitic carbon nitride has a greater than 0.0050 cm3 / g, preferably 0.0055 cm3 / g, and more preferably 0.0060 cm3 / g pore volume derived from pores having a specific pore diameter.

[0061] In the present invention, the amount of the pores having a specific pore diameter and the specific surface area of the graphitic carbon nitride can be determined by analyzing pore-size distribution plots obtained from adsorption-desorption isotherm of nitrogen measured using a surface area and porosity analyzer. The amount of the pores having a specific pore diameter included in the graphitic carbon nitride can be determined by using the Barrett-Joyner- Halenda (BJH) method to the obtained pore-size distribution plots. The specific surface area of the graphitic carbon nitride can be determined by using the Brunauer-Emmett-Teller (BET) method to the obtained pore-size distribution plots.

[0062] The graphitic carbon nitride of the present invention can show pale color for easy color adjustment, which are suitable and desired for cosmetic products. In preferred embodiments of the present invention, the graphitic carbon nitride can exhibit white color which is valuable for use in cosmetic products instead of ZnO.

[0063] The whiteness of the graphitic carbon nitride can be defined by a white value. The white value can be measured with a UV-vis diffuse reflectance spectrometer. The white value of the graphitic carbon nitride may range from -60 to 100, preferably -40 to 80. In preferred embodiments of the present invention, the graphitic carbon nitride exhibits the white value of -30 or more. The higher white value indicates the whiter appearance the graphitic carbon nitride exhibits.

[0064] The graphitic carbon nitride of the present invention can exhibit a UV A and / or B absorption property. In general, the graphitic carbon nitride of the present invention can exhibit the property to absorb UV rays with a wavelength less than 400 run. Preferably, the graphitic carbon nitride has the absorption effect against both regions of UV-B and UV-A rays. UV-B rays here means UV rays having a wavelength between 280 to 320 nm. UV-A rays here means UV rays having a wavelength between 320 to 400 nm.

[0065] The UV absorption property of the graphitic carbon nitride of the present invention can be represented by an onset absorption edge value (nm). The onset absorption edge value can be defined with a wavelength (nm) at an intersection of a straight line drawn to fit a region where an absorbance curve drops sharply from a shorter wavelength side of an absorbance curve, and a straight line drawn to fit an absorbance curve in a certain range of a wavelength range between 500 to 650 nm, where the absorbance curve becomes constantly low.

[0066] Example 3 in Figure 4 depicts an example of the onset absorption property being 405 nm, which is a wavelength at the intersection of the (1) straight line drawn to fit a region where the absorbance curve drops sharply from a shorter wavelength side of the absorbance curve, and the (2) straight line drawn to fit the absorbance curve in a certain range of a wavelength range between 500 to 650 nm, where the absorbance curve becomes constantly low. An absorption curve in a range of ultraviolet light and visible light can be measured by, for example, ultraviolet-visible (UV-vis) diffuse reflectance spectroscopy. The higher onset absorption edge value means the longer wavelength of rays the graphitic carbon nitride can filter.

[0067] The graphitic carbon nitride of the present invention may have the onset absorption edge value of 390 nm or more, preferably 395 nm or more. The graphitic carbon nitride of the present invention may have the onset absorption edge value of 480 nm or less, preferably 450 nm or less.

[0068] The graphitic carbon nitride of the present invention may have the onset absorption edge value ranging from 390 to 480 nm, preferably from 395 to 450 nm.

[0069] The graphitic carbon nitride of the present invention may be surface-treated or may not be surface-treated with a surface treating agent. Preferably, the graphitic carbon nitride is not surface-treated with a surface treating agent.

[0070] While not wishing to be bound by theory, it is believed that the fact that the graphitic carbon nitride of the present invention has the characteristic porous structure contributes to the color appearance of the graphitic carbon nitride which is suitable for cosmetic products. It is deduced that there are cracks of chemical bonds in the heptazine units in the inventive porous graphitic carbon nitride, such as cracks of chemical bonds between carbon atoms and nitride atoms. It is thought that the cracks can produce wider band gap of the graphitic carbon nitride, leading characteristic color appearance of the graphitic carbon nitride according to the present invention. Because the graphitic carbon nitride of the present invention has relatively large pore volume of pores, it is believed that there are large amount of cracks of chemical bonds in the heptazine units.

[0071] [Manufacturing Process]

[0072] The present invention also relates to a process for manufacturing the graphitic carbon nitride of the present invention.

[0073] Specifically, the present invention also relates to a process for manufacturing the graphitic carbon nitrides of the present invention, comprising: i) preparing at least one precursor compound; and ii) heating the at least one precursor compound at 450 °C or more for at least 1 minute.

[0074] The graphitic carbon nitride can be prepared by heating at least one precursor compound of the graphitic carbon nitride. One precursor compound may be used as a raw material of the graphitic carbon nitride, or two or more precursor compounds may be used in combination.

[0075] The precursor compound may be selected from, for example, urea, thiourea, melamine, guanidine, arginine, cyanamide, dicyandiamide, and a salt thereof, and combinations thereof. Preferably, the precursor compound is selected from urea, melamine, guanidine, arginine, and a salt thereof and the combination thereof, and in particular selected from melamine, urea, and a salt thereof and the combination thereof.

[0076] The salt of the precursor compound is not particularly limited, but mention can be made of salts with inorganic acids, such as carbonic acid and hydrochloric acid.

[0077] In one preferred embodiment of the present invention, only one precursor compound is used as a raw material in the preparation of the graphitic carbon nitride.

[0078] The temperature for heating the at least one precursor compound is at least 450 °C.

[0079] Preferably, the heating is carried out at 500 °C or more, and more preferably at 525 °C or more.

[0080] The period or the heating of the at least one precursor compound is at least 1 minute. Preferably, the period of the heating is at least 10 minutes, more preferably at least 20 minutes, and / or within 30 hours, and more preferably within 25 hours.

[0081] The heating of the precursor compound can be carried out in air, in noble gas, such as argon or helium, or in inert gas, such as nitrogen. In preferred embodiments of the present invention, the heating of the precursor compound is carried out in air or in argon.

[0082] In one preferred embodiment, the heating process may be carried out in a presence of oxygencontaining species, such as O2, humidity, O3, atomic O, and / or ionic oxygen, as an oxidizing agent. While not wishing to be bound by theory, it is believed that more porous graphitic carbon nitride can be obtained when the heating is carried out in the presence of oxygencontaining species. In the preferred embodiment, the heating is carried out in air, or in noble gas or inert gas including oxy gen-containing species.

[0083] In a preferred embodiment, in addition to oxygen in the air, the heating process is carried out in the presence of oxygen-containing species, such as O2, humidity, ozone O3, O atomic and / or ionic oxygen, as an oxidizing agent.

[0084] In a preferred embodiment, the heating process is carried out in a presence of oxygencontaining species of O2, in particular oxygen flux, and / or humidity. The term "oxygen flux" can mean an oxygen flow in the present specification.

[0085] Preferably the oxidizing agent used during the heating step is in a gas form.

[0086] According one embodiment the oxygen source is neither from permanganate salt nor from hydrogen peroxide.

[0087] 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 comprise a first heating step of the at least one precursor compound at 450 °C or more for at least 1 minute, and then a second heating step of the at least one precursor compound at 450 °C or more for at least 1 minute. The temperature for the first heating step and the temperature for the second heating step may be the same or different, but in general, the temperature for the second heating step is equal to or greater than the temperature for the first heating step. The temperature and period for the first and second heating steps are as explained above.

[0088] In one embodiment of the present invention, a cooling step is present between heating steps. Thus, in one embodiment, the cooling step is included between the first heating step and the second heating step. The temperature for the cooling step is not particularly limited, but for example, the temperature is cooled to a room temperature (about 25 °C). The period of the cooling step is not particularly limited, but for example is about from 1 minute to 24 hours.

[0089] [Use]

[0090] The present invention may relate to a use of the graphitic carbon nitride of the present invention as UV A and / or B absorbers in order to protect products from damages caused from UV A and / or B radiation. For example, the UV A and / or B absorber of the present invention can be used in paints, coatings, and cosmetics.

[0091] Because the graphitic carbon nitride of the present invention can show improved UV A and / or B absorption property, the use of the present invention can provide improved protection effect with products to be used. In addition, because the graphitic carbon nitride of the present invention can exhibit the suitable colors for cosmetics, the use of the present invention can provide the products with desired colored and attractive appearance.

[0092] [Composition]

[0093] The present invention also relates to a composition including the graphitic carbon nitride of the present invention.

[0094] Because the graphitic carbon nitride according to the present invention can be suspensible in water and in organic media, the present invention relates to a composition comprising the graphitic carbon nitride according to the present invention and water and / or at least one organic media. In this embodiment, the composition according to the present invention may be a suspension of the graphitic carbon nitride in in water and / or in organic media.

[0095] As the organic media, mention can be made of mono-alcohols, such as Ci-Ce monoalcohols, for example ethanol and propanol; polyols, such as Ci-Ce polyols, for example glycerin; and Cl-Ce alkylene glycols, such as ethylene glycol, and propylene glycol; and mixtures thereof.

[0096] Also, the composition according to the present invention is a cosmetic composition, in particular a cosmetic composition for keratinous substances, such as skin. In one preferred embodiment, the composition according to the present invention is a sunscreen composition.

[0097] The composition according to the present invention preferably does not comprise TiCh or ZnO. In another embodiment, the composition according to the present invention comprises Tith and / or ZnO in an amount of 5% by weight or less, more preferably 1% by weight or less, relative to the total weight of the composition. The graphitic carbon nitride of the present invention can be used in the composition instead of TiCh and ZnO, which are known as traditional inorganic UV filters.

[0098] Because the graphitic carbon nitride of the present invention can show improved UV absorption property, the composition of the present invention can exhibit improved UV protection effect. In addition, because the graphitic carbon nitride of the present invention can exhibit the suitable colors for cosmetics, the cosmetic composition according to present invention can provide keratinous substances with desired colored and attractive appearance.

[0099] EXAMPLES

[0100] The present invention will be described in a more detailed manner by way of examples. However, these examples should not be construed as limiting the scope of the present invention.

[0101] [Preparation]

[0102] The graphitic carbon nitride according to the present invention in powder form was prepared in the following Examples 1 to 5 and Comparative Examples 1 and 2.

[0103] Comparative Example 1

[0104] Various weights in the range from 3 g to 5 g of melamine powder as the precursor compound were heated at 550°C in air for 2 hours and then were mixed altogether to obtain the graphitic carbon nitride according to Comparative Example 1.

[0105] Comparative Example 2

[0106] 3 g of melamine powder as the precursor compound was heated at 600°C in argon gas flow (200 mL / min) for 8 hours to obtain the graphitic carbon nitride according to Comparative Example.

[0107] Example 1

[0108] 5 g of melamine powder as the precursor compound was heated at 550°C in air for 2 hours and then at 600°C in air for 16 hours to obtain the graphitic carbon nitride according to Example 1.

[0109] Example 2

[0110] 5 g of melamine powder as the precursor compound was heated at 550°C in air for 2 hours and then at 600°C in air for 19 hours to obtain the graphitic carbon nitride according to Example 2.

[0111] Example 3

[0112] Various weights in the range from 1 g to 10 g of urea powder as the precursor compound was heated at 600 to 605°C in air for 2 hours and then were mixed altogether to obtain the graphitic carbon nitride according to Example 3.

[0113] Example 4

[0114] 10 g of urea powder as the precursor compound was heated at 550°C in air for 1 hour and subsequently at 600°C in air for 30 minutes in air to obtain the graphitic carbon nitride according to Example 4.

[0115] Example 5

[0116] 10 g of urea powder as the precursor compound was heated at 600°C in air for 2 hours, cooled to room temperature, and then heated at 600°C in air for 1 hour to obtain the graphitic carbon nitride according to Example 5.

[0117] [Evaluation]

[0118] (Morphology and Crystalline Structure, and Chemical Structure)

[0119] The morphology of each of the graphitic carbon nitride was observed using a field emission scanning electron microscope (FE-SEM). The crystalline structure of each of the graphitic carbon nitride was characterized using X-ray diffraction (XRD) analysis. In the XRD pattern, the peak at 13° was assigned to (100) of graphitic carbon nitride having heptazine units; the peak at 27° was assigned to (002) plane of the c-axis in stacked sheets of graphitic carbon nitride, according to Luhong Zhang et al. (ACS Omega, 2018, 3(11), 15009—15017). The appearance of these peaks indicates the presence of the stacked sheets of graphitic carbon nitride having heptazine units.

[0120] The chemical structure of each of the graphitic carbon nitride was characterized via solid state nuclear magnetic resonance spectroscopy (NMR) using A vance 400 (Broker Corporation) and Fourier transform infrared spectroscopy (FT-IR). Solid-state NMR spectra were collected via cross-polarization / magic-angle spinning (CP / MAS) and dipolar decoupling / magic-angle spinning (DD / MAS) methods.

[0121] Figure 1 shows the representative (a)13C CP / MAS spectra, (b)13C DD / MAS spectra, and (c)15N CP MAS NMR spectra of the graphitic carbon nitride according to Example 3.

[0122] The peaks appearing at (Cl) and (C2) in both13C CP / MAS and DD / MAS NMR spectra shown in Figure 1 were respectively assigned to (Cl) carbon atoms neighboring two pyridinic nitrogen atoms in the heptazine units comprising the graphitic carbon nitride and a nitrogen atom in the amino group and (C2) carbon atoms neighboring two pyridinic nitrogen atoms and a center nitrogen atom in the heptazine units, according to Barbara Jurgens et al (J. Am. Chem. Soc., 2003, 125(34), 10288-10300) and Bettina V. Lotsch et al. (Chem. Eur. J., 2007, 13(17), 4969-4980). For the13C CP / MAS method, the sensitivity is enhanced by utilizing the magnetization transfer from protons, while the sensitivity is higher for carbon and nitrogen atoms located closer to protons. The semi-quantitative analysis was conducted by setting the pulse delay time to 4000 seconds for the13C DD / MAS method. The peaks appearing at (Nl), (N2), (N3), and (N4) in15N CP / MAS spectra shown in Figure 2 were respectively assigned to (Nl) pyridinic nitrogen atoms, (N2) center nitrogen atoms in heptazine units, (N3) secondary amino groups crosslinking the heptazine units, and (N4) nitrogen atoms in primary amino groups at the edge in the heptazine unit comprising the graphitic carbon nitride. The IR spectra were obtained using attenuated total reflection (ATR) method. The peak assigned to heptazine units appears at 804 cm'1, which is higher wavenumber than that of triazine units (814 cm'1for melamine, 808 cm'1for melam), according to Nan Liu et al (ACS Omega, 2020, 5, 12557-12567).

[0123] According to these analysis on the graphitic carbon nitride according to Example 4, all the appeared peaks were assigned to the C and N atoms in heptazine units. Thus, it was confirmed that the graphitic carbon nitride of the preset invention has the multi-layered sheets of graphitic carbon nitride with heptazine units. The same results are obtained in the graphitic carbon nitride according to the other examples.

[0124] Figure 2 shows the representative XRD patterns of the graphitic carbon nitride according to Example 3. The peak assigned to (100) of graphitic carbon nitride having heptazine units and the peak assigned to (002) plane appeared, indicating the presence of the stacked sheets of graphitic carbon nitride having heptazine units. The same results are obtained in the graphitic carbon nitride according to the other examples.

[0125] (UV Absorption Property and White Value)

[0126] The performance of light absorption of each of the graphitic carbon nitride in the wavelength range of ultraviolet light and visible light was evaluated using ultraviolet-visible (UV-vis) diffuse reflectance spectroscopy (UV2500PC, Shimadzu Corporation) equipped with an integrating sphere. The UV-vis absorption spectra of the liquids suspended with 0.01 % by weight of each of the graphitic carbon nitride in Fine quartz cell (two transparent Sides, 2 mm (optical path length) x 10 mm x H45 mm, Tokyo Garasu Kikai Co., Ltd.) were collected using UV-Visible spectrophotometer (V750, Jasco Inc.) equipped with an integrating sphere.

[0127] Water / isopropanol (99:1 by weight), water / PG (a volume ratio: 50:50) or water alone was used as a suspension media. The onset adsorption edge was estimated from UV-vis diffuse reflectance spectrum of each sample.

[0128] White value was also evaluated from UV-vis diffuse reflectance spectrum of each sample. The calculation of white value was conducted using the software of Shimadzu equipped to the device, where illuminant D65 was used as a standard illuminant and a viewing angle was set to 10°. BaSCL standard white plate was used as a reference.

[0129] The diffuse transmittance in the wavelength region from 250 nm to 450 nm on the plates of poly methyl methacrylate (PMMA) (50mm x 50mm, Helioplate HD6; Helioscreen) were measured using the UV-2000S in-vitro sunscreen analyzer (Labsphere, Inc.) equipped with an integrating sphere. The powder sample of graphitic carbon nitride was dispersed in (a) diisopropyl sebacate and (b) water with hydroxyethyl cellulose. Then 30 mg of the dispersions were applied on the PMMA plates and the solvents were dried.

[0130] (Porosity and Specific Surface Area)

[0131] The porosity and specific surface area of each of the graphitic carbon nitride were evaluated using an adsorption-desorption isotherm of nitrogen. The sample was introduced in a quartz tube. The tube was evacuated at 423 K for 5 hours using a vacuum degasser at the pretreatment stage. 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, followed by gradual introduction of nitrogen into the tube to collect the adsorption-desorption isotherm. The porosity was evaluated via the Barrett- Joyner-Halenda (BJH) pore-size distribution plots obtained from adsorption curves of the adsorption-desorption isotherm. The specific surface area was determined from the adsorption isotherm using Brunauer-Emmett-Teller (BET) theory.

[0132] The obtained BJH plots according to Examples 1 to 5 and Comparative Examples 1 and 2 are shown in Figures 3(A) and 3(B). As can be seen from these BJH plots, the characteristic structures were confirmed.

[0133] The graphitic carbon nitride according to Comparative Example 1 comprised the pores with a diameter size in the range of 2 nm to 50 nm with a pore volume in the range of 0.00035 cm3g' 'nm'1to 0.0018 cm3g'1nm'1.

[0134] The graphitic carbon nitride according to Comparative Example 2 comprised the pores with a diameter size in the range of 4 nm to 59 nm with a pore volume in the range up to 0.0019 cm 3 g -1 nm -1.

[0135] The graphitic carbon nitride according to Example 1 comprised the pores with a diameter size in the range of 2 nm to 50 nm with a pore volume in the range of 0.0028 cm3g‘1nm‘1to 0.0068 cm3g'1nm'1. Particularly, the volumes of pores having the diameter size of about 2 nm, about 3 nm, and about 20 nm were respectively as large as 0.0064 cm3g'1nm'1, 0.0068 cm3g'1nm'1, and 0.0061 cm3g’1nm’1.

[0136] The graphitic carbon nitride according to Example 2 comprised the pores with a diameter size in the range of 2 nm to 50 nm with a pore volume in the range of 0.0021 cm3g’1nm‘1to 0.0074 cm3g'1nm'1. Particularly, the volumes of the pores having the size of about 3 nm, about 4 nm, and 44 nm were respectively as large as 0.0074 cm3g'1nm‘1, 0.0057 cm3g'1nm'1, and 0.0049 cm3genin'1.

[0137] The graphitic carbon nitride according to Example 3 comprised the pores with a diameter size in the range of 2 nm to 38 nm with a pore volume in the range of 0.0025 cm3g‘1nm'1to 0.0225 cm 3 g -1 nm -1.

[0138] The graphitic carbon nitride according to Example 4 comprised the pores with a diameter size in the range of 1 nm to 44 nm with a pore volume in the range of 0.0021 cm3g‘1nm'1to 0.0066 cm3g"1nm'1. Particularly, the volume of the pore having the diameter size of about 3 nm and about 28 nm were respectively as large as 0.058 cm^nm'1and 0.0066 cm3g’1nm"1.

[0139] The graphitic carbon nitride according to Example 5 comprised the pores with a diameter size in the range of 2 nm to 44 nm with a pore volume in the range of 0.005 cm3g'1nm'1to 0.0176 cm3g’1nm'1.

[0140] Thus, the graphitic carbon nitride according to each of Examples 1 to 5 had a characteristic porous structure that has a greater than 0.0045 cm3 / g pore volume derived from the first type of pores having a specific pore diameter of 1 nm or more and less than 15 nm, and derived from the second type of pores having a specific pore diameter of 15 nm or more and 50 nm or less.

[0141] Also, the results are summarized in Table 1 below. Table 1

[0142] Table 1 shows that the graphitic carbon nitride with a favorable white value has the onset absorption edge value less than 443 nm and the specific surface area greater than 12. (Comparison of UV Absorption Property)

[0143] The absorption spectra obtained via UV-vis diffuse reflectance measurement of the as- synthesized powder of graphitic carbon nitride according to Examples 1 to 3 are shown in Figure 4, as the representative examples. All the powder samples exhibited absorption in the wavelength range of UV, which is lower than 400 nm.

[0144] The absorption spectra of liquids suspended with 0.01 wt% of graphitic carbon nitride according to Example 3 in water / isopropanol (99:1) and water / propylene glycol (50:50) are shown in Figure 5, as the representative example. All these suspensions exhibited absorption in the wavelength range of UV, which is lower than 400 nm.

[0145] The diffuse transmittance in the wavelength region from 250 nm to 450 nm of the graphitic carbon nitride according to Example 3, which was suspended in oil-based medium and then applied on polymethyl methacrylate (PMMA) plate for sunscreen evaluation, was compared to those of TiCb (average primary particle size: 15 nm) and ZnO (average primary particle size: 20 nm), which are commonly used as inorganic UV filters. Each of the samples was dispersed in diisopropyl sebacate to obtain suspensions comprising 3% by weight of the graphitic carbon nitride. Then 30 mg of the suspension was applied on a polymethyl methacrylate (PMMA) plate (50mm x 50mm, Helioplate HD6; Helioscreen), and diffuse transmittance in the wavelength region from 250 nm to 450 nm was measured using the UV-2000S in-vitro sunscreen analyzer (Labsphere, Inc.). The result is shown in Figure 7. As can be seen from Figure 7, it is clear that the graphitic carbon nitride of the present invention could show a higher absorption property than TiCh and ZnO in the UV wavelength region lower than 400 nm.

[0146] The diffuse transmittance in the wavelength region from 250 nm to 450 nm of the graphitic carbon nitride according to Example 3, which was suspended in water-based medium and then applied on PMMA plate for sunscreen evaluation, also displayed a UV absorption property. The sample was dispersed in water containing 1% by weight of hydroxy ethyl cellulose to obtain a suspension comprising 1% by weight of the graphitic carbon nitride. Then 30 mg of the suspension was applied on a PMMA plate (50mm x 50mm, Helioplate HD6; Helioscreen) and then dried for a while, and diffuse transmittance in the wavelength region from 250 nm to 450 nm was measured using the UV-2000S in-vitro sunscreen analyzer (Labsphere, Inc.). The result is shown in Figure 8. As can be seen from Figure 8, it is clear that the graphitic carbon nitride of the present invention can show an absorption property in the UV wavelength region lower than 400 nm.

[0147] Accordingly, it can be concluded that the graphitic carbon nitride of the present invention is very useful as UV absorbers for various products, in particular cosmetic products, since it can provide an improved UV absorption property and exhibit a desired colors in particular for cosmetic use.

Claims

CLAIMS1. A graphitic carbon nitride with porous structures, wherein the graphitic carbon nitride has at least one heptazine unit, and has a pore volume greater than 0.0045 cm3 / g derived from first type of pores having a specific pore diameter of 1 nm or more and less than 15 nm and derived from second types of pores having a specific pore diameter of 15 nm or more and 50 nm or less.

2. The graphitic carbon nitride according to Claim 1, comprising at least one having a pore diameter ranging from 1 to 500 nm, preferably from 2 to 400 nm, more preferably from 3 to 300 nm, and even more preferably from 5 to 200 nm.

3. The graphitic carbon nitride according to Claim 1 or 2, having a specific surface area determined by BET method ranging from 5 to 300 m2 / g, preferably 15 to 250 m2 / g, and more preferably 30 to 200 m2 / g.

4. The graphitic carbon nitride according to any one of the preceding claims, having a white value ranging from -60 to 100, preferably -40 to 80.

5. The graphitic carbon nitride according to any one of the preceding claims, having an onset absorption edge value ranging from 390 to 480 nm, preferably from 395 to 450 nm.

6. The graphitic carbon nitride according to any one of the preceding claims, having a pore volume greater than 0.0055 cm3 / g derived from pores having a specific pore diameter ranging from 1.5 nm to 5 nm.

7. The graphitic carbon nitride any one of the preceding claims, having a pore volume greater than 0.0045 cm3 / g derived from pores having a specific pore diameter in the range of 20 nm to 45 nm.

8. A process for manufacturing the graphitic carbon nitride according to any one of the preceding claims, comprising: i) preparing at least one precursor compound; and ii) heating the at least one precursor compound at 450 °C or more for at least 1 minute.

9. The process according to Claim 8, wherein the ii) heating is carried out in a presence of oxygen-containing species such as O2, humidity, O3, O atomic, and / or ionic oxygen; preferably the oxidizing agent used during the heating step is in a gas form; more preferably the oxygen-containing species is neither from permanganate salt nor from hydrogen peroxide.

10. A use of the graphitic carbon nitride according to any one of Claims 1 to 7, as a paint active, as a pigment, as a filler especially of plastics or as a cosmetic active.

11. A use of the graphitic carbon nitride according to any one of Claims 1 to 7 as a UV absorber.

12. A composition comprising the graphitic carbon nitride according to any one ofClaims 1 to 7 and water and / or at least one organic media.

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

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

15. The composition according to Claim 13 or 14, which does not comprise TiCh or ZnO, or comprises TiCh and / or ZnO in an amount of 5% by weight or less, more preferably 1% by weight or less, relative to the total weight of the composition.

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