GRAPHIC CARBON NITRID WITH METALLIC OXIDE AND PROCESS LIKELY

Abstract

GRAPHITICAL CARBON NITRIDE WITH METAL OXIDE AND PROCESS FOR PRODUCING ITSELF The present invention relates mainly to a process for preparing graphitic carbon nitride, comprising a step of heating at least one precursor compound with at least one metal oxide particle. The present invention also relates to a mixture product prepared by the process according to the present invention, comprising the graphitic carbon nitride and the metal oxide particle. Figure for the abstract: Figure 1

Description

Title of the invention: GRAPHITICAL CARBON NITRID WITH METALLIC OXIDE AND PROCESS FOR PRODUCING THEREOF technical field

[0001] The present invention relates mainly to a process for preparing graphitic carbon nitrides, in particular a process for preparing a mixture of graphitic carbon nitride with metal oxide. PRIORITY OF THE TECHNOLOGY

[0002] UV protection is one of the essential factors in cosmetic products. Graphitic carbon nitride, an inorganic compound, is known to exhibit UV absorption properties. Some documents have already been published concerning the manufacturing techniques for carbon nitride materials.

[0003] For example, JP2020-152609A discloses a process for producing graphitic carbon nitride at a higher yield and lower cost, and for supplying a new graphitic carbon nitride.

[0004] Cosmetic makeup compositions are used to give keratinous substances, such as skin, and in particular facial skin, a desired color appearance. The development of a new, efficient manufacturing process for graphitic carbon nitrides as environmentally friendly, UV-absorbing materials is required. DISCLOSURE OF THE INVENTION

[0005] An objective of the present invention is to propose an efficient manufacturing process for graphitic carbon nitrides suitable for cosmetic use.

[0006] The above objective of the present invention can be achieved by a process for preparing graphitic carbon nitrides, comprising a step of heating at least one precursor compound with at least one metal oxide particle.

[0007] The precursor compound can be chosen from urea, thiourea, melamine, guanidine, arginine, cyanamide, dicyandiamide, and one of their salts, and their combinations.

[0008] The metal oxide particle can be chosen from silica (SiO2), zeolite and aluminium oxide (Al2O3) particles, and their mixtures and composites.

[0009] The metal oxide particle can have an average particle size ranging from 0.01 to 30 µm, preferably from 0.05 to 20 µm.

[0010] The weight ratio between the precursor compound and the metal oxide particle can range from 1:99 to 99:1, preferably from 1:49 to 49:1, more preferably from 1:24 to 24:1, even more preferably from 1:9 to 9:1, and in particular from 1:5 to 5:1.

[0011] The heating can be carried out at a minimum of 450 °C and for a duration of at least 1 minute.

[0012] Heating can be carried out in the presence of a species containing oxygen, such as O2 (in particular with oxygen flux) and / or humidity.

[0013] The process may include an additional preheating step for the precursor compound or the metal oxide particle, or both the precursor compound and the metal oxide particle.

[0014] Graphitic carbon nitride can have a porous structure.

[0015] The present invention also relates to a mixture product prepared by the process according to the present invention, comprising graphitic carbon nitride and metal oxide particle.

[0016] The weight ratio between the graphitic carbon nitride and the metal oxide particle in the product can range from 1:99 to 99:1, preferably from 1:49 to 49:1, more preferably from 1:24 to 24:1, even more preferably from 1:9 to 9:1, and in particular from 1:5 to 5:1.

[0017] The mixture product may have an initial absorption front value ranging from 390 to 430 nm, preferably from 395 to 420 nm.

[0018] The present invention also relates to a use of the mixture product according to the present invention as UV absorbers.

[0019] The present invention also relates to a composition, preferably a cosmetic composition for keratinous substances, such as skin, comprising the mixture product according to the present invention.

[0020] The composition may be a sunscreen composition. Brief description of the drawings

[0021] [Fig.1] Fig.1 shows the IR spectra of the products according to Example 4 and Comparative Example 3 in the examples.

[0022] [Fig.2] Fig.2 shows a comparison of the absorption spectra curve UV / vis between the products according to Example 1 and Comparative Example 1 in the form of a suspension at 0.1% by weight in water.

[0023] [Fig.3] Fig.3 shows the UV / vis absorption spectra curve measured with the mixture product according to Example 4 in the form of a 0.1% weight suspension in water. Best embodiment of the invention

[0024] After extensive research, the inventors made an astonishing discovery that graphitic carbon nitrides having at least one heptazine motif can be efficiently produced by heating precursor compounds with metal oxide particles, and that the product is suitable for cosmetic use, and thus finalized the invention.

[0025] Thus, the present invention relates mainly to a process for preparing graphitic carbon nitrides comprising a step of heating precursor compounds with metal oxide particles.

[0026] The inventors of the present invention have discovered that the manufacture of graphitic carbon nitrides provides the graphitic carbon nitrides with improved whiteness.

[0027] Thus, the process according to the present invention can produce graphitic carbon nitrides with improved whiteness.

[0028] The present invention will be described in detail below. [Process]

[0029] The present invention relates to a process for preparing graphitic carbon nitride, comprising a step of heating at least one precursor compound with at least one metal oxide particle.

[0030] The term "graphitic" in graphitic carbon nitride here means that the carbon nitride has a planar structure similar to graphite. Thus, the graphitic carbon nitride of the present invention may have a layered or sheet-like structure. Graphitic carbon nitride is generally solid at room temperature and in powder form.

[0031] The graphitic carbon nitride of the present invention may comprise at least one heptazine motif. In this patent application, the heptazine motif refers to a heterofused ring consisting of three hetero rings composed of carbon and nitrogen atoms, represented by C6N7. Thus, the graphitic carbon nitride of the present invention may have a heptazine-based monolayer structure. The graphitic carbon nitride of the present invention may comprise at least one heptazine motif, at least one triazine motif, and one of their combinations. The presence of the heptazine motif can be determined by X-ray diffraction (XRD) analysis, Fourier transform infrared (FT-IR) spectroscopy, and nuclear magnetic resonance (NMR) spectroscopy.

[0032] The graphitic carbon nitride of the present invention may have a porous structure. More specifically, the graphitic carbon nitride of the present invention may have a nanoporous structure. The pores may exist on the layered structure of graphitic carbon nitride between heptazine motifs and triazine motifs.

[0033] The graphitic carbon nitride of the present invention may exhibit UV absorption properties. Preferably, the graphitic carbon nitride exhibits absorption in both the UV-B and UV-A regions. UV-B rays here refer to UV rays with a wavelength between 280 and 320 nm. UV-A rays here refer to UV rays with a wavelength between 320 and 400 nm. An absorption curve in the ultraviolet and visible light range can be measured, for example, by ultraviolet-visible diffuse reflectance spectroscopy (UV-vis).

[0034] The process according to the present invention comprises a step of heating at least one precursor compound with at least one metal oxide particle. Thus, the process according to the present invention comprises a step of heating a mixture of at least one precursor compound and at least one metal oxide particle.

[0035] A precursor compound can be used as a raw material for graphitic carbon nitride, or two or more precursor compounds can be used in combination.

[0036] The precursor compound may be selected from precursors known to the person skilled in the art, for example, urea, thiourea, melamine, guanidine, arginine, cyanamide, dicyandiamide and one of their salts, and combinations thereof (Chem. Rev. 2016, 116, 7159-7329, Ong, WJ; Tan, LL; Ng, YH; Yong, ST; Chai, SP, Catalysts 2019, 9(10), 805, Seong Jun Mun and Soo-Jin Park; https: / / d0i.0rg / l0,3390 / catal9100805). Preferably, the precursor compound is selected from urea, melamine, guanidine, arginine and one of their salts, and combinations thereof.

[0037] The salt of the precursor compound is not particularly limited, but examples include salts with inorganic acids, such as carbonic acid and hydrochloric acid.

[0038] In a preferred embodiment of the present invention, only one precursor compound is used.

[0039] At least one precursor compound is heated with at least one metal oxide particle in the process. The metal oxide particle may be selected from silica (SiO2), zeolite, aluminum oxide (Al2O3) particles and mixtures thereof, and preferably from silica (SiO2) and zeolite. One type of metal oxide particle may be used, or two or more types of metal oxide particles may be used in combination. The metal oxide particle may serve as a catalyst for the synthesis of graphitic carbon nitrides.

[0040] The metal oxide particle may have an average particle size of 0.01 µm or more, preferably 0.05 µm or more, and / or 30 µm or less, preferably 25 µm or less, and more preferably 20 µm or less. The term "average particle size" used here may represent an average diameter of the average volume size given by the statistical particle size distribution to half the population, designated by D50. For example, the average particle size may be measured by a laser diffraction particle size distribution analyzer, such as the Mastersizer 2000 from Malvem Corp.

[0041] The metal oxide particle may have an average particle size ranging from 0.01 to 30 pm, preferably from 0.05 to 25 pm.

[0042] In one embodiment of the present invention, the metal oxide particle is porous. In this embodiment, the pore diameter of the metal oxide particle is not particularly limited, but can range from 0.3 nm to 1 nm.

[0043] The weight ratio between the precursor compound and the metal oxide particle is not particularly limited. For example, the weight ratio between the precursor compound and the metal oxide particle can range from 1:99 to 99:1, preferably from 1:49 to 49:1, more preferably from 1:24 to 24:1, even more preferably from 1:9 to 9:1, and in particular from 1:5 to 5:1.

[0044] The process according to the present invention includes a step of heating a mixture of at least one precursor compound and at least one metal oxide particle.

[0045] The heating temperature can be at least 450 °C. Preferably, the heating is carried out at 500 °C or more, and more preferably at 525 °C or more, and can be 800 °C or less.

[0046] The heating time can be at least 1 minute. Preferably, the heating time is at least 10 minutes, more preferably at least 20 minutes, and / or up to 30 hours, and more preferably up to 25 hours.

[0047] Heating can be carried out in air, in a noble gas, such as argon or helium, or in an inert gas, such as nitrogen. In preferred embodiments of the present invention, heating is carried out in air or in argon. In a preferred embodiment, heating is carried out in the presence of oxygen, such as in air.

[0048] In a preferred embodiment, the heating process can be carried out in the presence of an oxygen-containing species, such as O2, moisture, O3, atomic O, and / or ionic oxygen, as an oxidizing agent. Without wishing to be bound by theory, it is estimated that a more porous graphitic carbon nitride can be obtained when heating is carried out in the presence of a species containing oxygen. In the preferred embodiment, heating is carried out in air, or in a noble gas or an inert gas including an oxygen-containing species.

[0049] In a preferred embodiment, in addition to oxygen in the air, the heating process is carried out in the presence of an oxygen-containing species, such as O2, moisture, ozone O3, atomic O and / or ionic oxygen, as an oxidizing agent.

[0050] In a preferred embodiment, the heating process is carried out in the presence of an oxygen-containing species of O2, in particular an oxygen stream and / or moisture. The term "oxygen stream" may mean an oxygen flow in this patent specification.

[0051] Preferably, the oxidizing agent used during the heating step is in gaseous form.

[0052] According to one embodiment, the oxygen source is neither permanganate salt nor hydrogen peroxide.

[0053] In one embodiment of the present invention, the heating process includes at least two heating stages at the same or different temperatures. In other words, the heating process may include a preheating stage before the heating stage as explained above.

[0054] The preheating step can be applied to the precursor compound or to the metal oxide particle, or to both the precursor compound and the metal oxide particle.

[0055] The preheating temperature can be at least 200 °C. Preferably, preheating is carried out at 250 °C or more, and more preferably at 275 °C or more, and can be 800 °C or less.

[0056] The preheating time can be at least 5 minutes. Preferably, the preheating time is at least 10 minutes, more preferably at least 20 minutes, and / or up to 30 hours, and more preferably up to 25 hours.

[0057] Preheating can be carried out in air, in a noble gas such as argon or helium, or in an inert gas such as nitrogen. In preferred embodiments of the present invention, preheating is carried out in air or in argon. In a preferred embodiment, the heating process is carried out in the presence of oxygen, such as in air.

[0058] In one embodiment of the present invention, a cooling step is present 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, but, for example, the temperature is cooled to ambient temperature. (approximately 25 °C). The duration of the cooling stage is not particularly limited, but is, for example, from approximately 1 minute to 24 hours.

[0059] The process according to the present invention can produce graphitic carbon nitride in an improved yield. For example, the process according to the present invention can produce graphitic carbon nitride in a weight yield of 6% or more, preferably 7% or more, and more preferably 8% or more. [Mixture product]

[0060] The present invention also relates to the mixture product prepared by the process according to the present invention.

[0061] The product of the present invention comprises graphitic carbon nitrides and metal oxide particles. Thus, the product of the present invention is a mixture of graphitic carbon nitride and metal oxide particles. The same descriptions of graphitic carbon nitride and metal oxide particles can be applied to the product explanations given here.

[0062] The weight ratio between the graphitic carbon nitride and the metal oxide particle in the product is not particularly limited. For example, the weight ratio between the graphitic carbon nitride and the metal oxide particle in the product can range from 1:99 to 99:1, preferably from 1:49 to 49:1, more preferably from 1:24 to 24:1, even more preferably from 1:9 to 9:1, and in particular from 1:5 to 5:1.

[0063] The mixture product of the present invention may exhibit UV absorption properties due to the presence of graphitic carbon nitride. Preferably, the mixture product exhibits absorption in both the UV-B and UV-A regions.

[0064] The UV absorption property of the mixture product of the present invention can be represented by an initial absorption front value (nm). The initial absorption front 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 on a shorter wavelength side of an absorbance curve, and a straight line drawn to fit an absorbance curve in a wavelength range of 500 to 550 nm.

[0065] Example 1 of [Fig. 2] represents an example of an initial absorption property of 400 nm, which is a wavelength at the intersection of (1) a straight line drawn to fit a region where the absorbance curve drops sharply on a shorter wavelength side of the absorbance curve, and (2) a straight line drawn to fit the absorbance curve in a certain range of a wavelength range between 500 and 550 nm, where the absorbance curve becomes consistently weak. An absorption curve in a range of ultraviolet light and visible light can be measured, for example, by diffuse reflectance spectroscopy in the ultraviolet-visible (UV-vis).

[0066] The inventors of the present invention have made a surprising discovery: the mixture product of the present invention can exhibit a lower initial absorption front value than a product produced without the metal oxide particle. The lower initial absorption front value indicates that the less color the product contains, the fewer colored materials can achieve enhanced whiteness. Thus, the mixture product of the present invention is versatile and applicable to various uses, particularly in cosmetic products.

[0067] The mixture product of the present invention may have an initial absorption front value of 390 nm or more, preferably 395 nm or more, and generally 430 nm or less, preferably 420 nm or less.

[0068] The graphitic carbon nitride of the present invention can have an initial absorption front value ranging from 390 to 430 nm, preferably from 395 to 420 nm. [Use]

[0069] The present invention also relates to the use of the mixture product of the present invention as a UV absorber. For example, the UV absorber of the present invention can be used in paints, coatings, as a filler, particularly for plastics, and in cosmetics. The UV absorber can be a UVA and / or UVB absorber.

[0070] Since the mixture product of the present invention has sufficient UV absorption property and less color, it is very useful for various products requiring UV protection. [Composition]

[0071] The present invention also relates to a composition comprising the mixture product of the present invention. Preferably, the composition according to the present invention is a cosmetic composition, and in particular a cosmetic composition for keratinous substances, such as skin. In a preferred embodiment, the composition according to the present invention is a sunscreen composition.

[0072] Keratinous substance here means a material containing keratin as its main constituent element, and examples of this include skin, scalp, nails, lips, hair, and the like, and preferably skin.

[0073] Since the mixture product of the present invention can exhibit sufficient UV absorption properties and less color, the composition The cosmetic product according to the present invention can provide keratinous substances with sufficient protection against UV radiation without changing the color.

[0074] Details of the compositions for use according to the present invention are explained in the section entitled [Process] above. EXAMPLES

[0075] The present invention will be described in more detail by means of examples. However, these examples should not be interpreted as limiting the scope of the present invention. [Preparation] Example 1

[0076] 0.6 g of urea was preheated to 300 °C in air for 1 hour. The preheated urea was mixed with 2.4 g of zeolite (HS-642, powder, sodium mordenite, FUJIFILM Wako Chemical Corporation, crystal size: 0.1 pm x 0.5 pm, average particle size: 12 pm, pore openings: 0.7 nm) and the mixture was heated to 550 °C in air for 1 hour to produce the graphitic carbon nitride and zeolite mixture. Comparative example 1

[0077] 3 g of urea were preheated to 300 °C in air for 1 hour. The urea preheated alone was heated to 550 °C in air for 1 hour to produce graphitic carbon nitride alone. Example 2

[0078] A mixture of 10 g of urea and 3 g of silica (average particle size: 5 pm) was heated to 600 °C in air for 2 hours to produce the mixture of graphitic carbon nitride and silica. Example 3

[0079] 3 g of silica (average particle size: 5 pm) were preheated to 600 °C in air for 2 hours. The preheated silica was mixed with 10 g of urea, and the mixture was heated to 600 °C in air for 2 hours to produce the mixture of graphitic carbon nitride and silica. Comparative Example 2

[0080] 10 g of urea were heated to 600 °C in air for 2 hours to produce the graphitic carbon nitride alone. Example 4

[0081] 3 g of silica (average particle size: 5 pm) were preheated to 600 °C in air for 2 hours. The preheated silica was mixed with 10 g of urea, and the mixture was heated to 300 °C in air for 4 hours, then to 600 °C in air for 2 hours to produce the mixture of graphitic carbon nitride and silica. Comparative Example 3

[0082] 10 g of urea were heated to 300 °C in air for 4 hours and then to 600 °C in air for 2 hours to produce graphitic carbon nitride alone. [Evaluation]

[0083] The following evaluations were carried out on the powder samples obtained.

[0084] (Yield)

[0085] The yield of the graphitic carbon nitride obtained was calculated in each of the processes by measuring the weight of the products.

[0086] (Morphological analysis)

[0087] The IR spectrum of the powder produced was obtained using the attenuated total reflection (ATR) method. The peak attributed to the heptazine motifs appears at 804 cm⁻¹, which is a higher wavenumber than that of the triazine motifs (814 cm⁻¹ for melamine, 808 cm⁻¹ for melam), according to Nan Liu et al (ACS Omega, 2020, 5, 12557-12567).

[0088] Fig. 1 shows the IR spectra of the products according to Example 4 and Comparative Example 3. The spectra of the product according to Example 1 show a peak derived from the structure of graphitic carbon nitride and silica.

[0089] Furthermore, according to the morphological analysis, it was confirmed that all the graphitic carbon nitrides produced in the examples include heptazine motifs.

[0090] (UV diffuse absorption / transmittance properties)

[0091] The light absorption performance of the powder samples in the ultraviolet and visible light wavelength range was evaluated using ultraviolet-visible (UV-vis) diffuse reflectance spectroscopy (UV2500PC, Shimadzu Corporation) coupled with an integrating sphere.

[0092] The UV-Vis absorption spectra of powder samples suspended in water in a 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 a UV-Visible spectrophotometer (V750, Jasco Inc.) coupled to an integrating sphere. The suspensions were sonicated using an ultrasonic cleaner (ASU-3M, AS ONE Corporation) prior to measurement.

[0093] The initial adsorption front value was estimated from the diffuse UV / vis reflectance spectrum of each sample.

[0094] Figure 2 shows a comparison of the UV / vis absorption spectrum curve between Example 1 and Comparative Example 1. Example 1 showed a lower initial absorption front value than Comparative Example 1, which indicates that the powder obtained according to Example 1 has less color than Comparative Example 1.

[0095] In addition, [Fig.3] shows the UV / vis absorption spectra curve measured with the mixture product according to Example 4 in the form of a 0.1% wt% suspension in water.

[0096] The results are summarized in Table 1 below.

[0097] [Tables 1] Metal oxide Heating condition Initial absorption front value (nm) Yield (%) Ex. 1 Zeolite 550 °C, 1 h, in air 400 11 Ex. comp. 1 - 550 °C, 1 h in air 410 5 Ex. 2 SiO2 600 °C, 2 h, in air nd 10 Ex. 3 SiO2 (preheated @600 °C, 2 h, in air) 600 °C, 2 h, in air nd 13.5 Ex. comp. 2 - 600 °C, 2 h, in air nd 3.5 Ex. 4 SiO2 (preheated @600 °C, 2 h, in air) 300 °C, 4 h 600 °C, 2 h, in air nd 11 Ex. comp. 3 - 300 °C, 4 h 600 °C, 2 h, in air nd 4

[0098] As can be seen from the results in Table 1, the process according to Examples 1 to 4 was able to produce graphitic carbon nitride in higher yield. Thus, the process according to the present invention was able to efficiently produce graphitic carbon nitride. Furthermore, the mixture product produced according to Example 1 exhibited a lower initial absorption edge value than that of Comparative Example 1, indicating that the mixture product according to Example 1 is less colored. The lower initial absorption front value indicates that the products according to the present invention exhibit improved whiteness.

[0099] Thus, it can be concluded that the process according to the present invention is very useful for the manufacture of graphitic carbon nitrides, and that the product prepared by the process of the present invention is very useful for various products requiring UV protection, in particular cosmetics, because it can provide keratinous substances with sufficient protection against UV without a change in shade.

Claims

Demands

1. Process for preparing graphitic carbon nitride comprising a step of heating at least one precursor compound with at least one metal oxide particle.

2. Process according to claim 1, wherein the precursor compound is selected from urea, thiourea, melamine, guanidine, arginine, cyanamide, dicyandiamide, and one of their salts, and combinations thereof.

3. Process according to claim 1 or 2, wherein the metal oxide particle is selected from silica (SiO2), zeolite, aluminium oxide (Al2O3), and mixtures and composites thereof.

4. A process according to any one of the preceding claims, wherein the weight ratio between the precursor compound and the metal oxide particle ranges from 1:99 to 99:1, preferably from 1:49 to 49:1, more preferably from 1:24 to 24:1, even more preferably from 1:9 to 9:1, and in particular from 1:5 to 5:

1.

5. A process according to any one of the preceding claims, wherein the heating is carried out in the presence of oxygen-containing species, such as O2, moisture, O3, atomic O and / or ionic oxygen as an oxidizing agent; preferably, the oxidizing agent used during the heating step is in gaseous form; more preferably, the oxygen-containing species is neither permanganate salt nor hydrogen peroxide.

6. A process according to any one of the preceding claims, comprising an additional preheating step for the precursor compound or the metal oxide particle, or both the precursor compound and the metal oxide particle.

7. A mixture product prepared by the process according to any one of the preceding claims, wherein the weight ratio between the graphitic carbon nitride and the metal oxide particle ranges from 1:99 to 99:1, preferably from 1:49 to 49:1, more preferably from 1:24 to 24:1, even more preferably from 1:9 to 9:1, and in particular from 1:5 to 5:

1.

8. Use of the mixture product according to claim 7 as a UV absorber.

9. Use of the UV absorber according to claim 8, in paints, coatings, as a filler, in particular for plastics, and cosmetics.

10. Composition, preferably a cosmetic composition for keratinous substances, such as skin, comprising the mixture product according to claim 7.

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