Composition for improving stability of avobenzone-titanium dioxide system and application thereof

Abstract

The invention relates to the stability of a sunscreen composition in the field of ultraviolet absorption, in particular to a composition for improving the stability of an avobenzone-titanium dioxide system and application of the composition. Specifically, the invention provides a method for improving the stability of an avobenzone-titanium dioxide system, and the method comprises the following steps: firstly, pretreating titanium dioxide by using caprylyl glycol, and then mixing a mixture of caprylyl glycol and titanium dioxide with avobenzone. The method provided by the invention can improve the stability and lasting protective power of the sunscreen system.

Description

Technical Field

[0001] The present invention relates to the stability of a sunscreen composition in the field of ultraviolet absorption, and in particular to a composition for improving the stability of an avobenzone-titanium dioxide system and applications thereof. Background Art

[0002] Avobenzone, also known as 1-(4-methoxyphenyl)-3-(4-tert-butylphenyl)propane-1,3-dione, butyl methoxydibenzoylmethane, or BMDBM, was approved for use in cosmetics in Europe in 1978 and in the United States in 1988. It is one of the few approved long-wavelength ultraviolet (UVA) absorbers in the world, with a maximum permitted concentration of 5% in China, the European Union, and the United States. It has a broad and intense absorption range, with a maximum UV absorption peak at 357nm. However, it is inherently unstable and easily interacts with other metals in the system, reducing its UV absorption capacity.

[0003] Titanium dioxide (TiO2), when its original particle size is less than 100nm, can be used as a sunscreen, absorbing, reflecting, and scattering light. China, the EU, and the US allow a maximum mass fraction of 25%. However, at this particle size, TiO2 has a high surface energy, and even with surface treatments such as triethoxycaprylylsiloxane, stearic acid, aluminum oxide, and silicon dioxide, some titanium ions are still exposed.

[0004] Avobenzone-titanium dioxide system is widely used in sunscreen products on the market due to the synergistic effect of the two, which can provide high protection. However, over time, this system has exposed a significant problem: the free titanium ions in titanium dioxide form a complex with avobenzone (BMDBM-Ti (such as Figure 1 As shown in the figure, this ultimately leads to poor stability of the entire system and weakened sun protection effect, which is undoubtedly an industry pain point that needs to be urgently addressed.

[0005] IN202017043035A discloses a cosmetic composition comprising 0.1 to 20 wt% of avobenzone, an organic cosmetic active ingredient with ligand characteristics, and 0.1 to 30 wt% of titanium dioxide particles coated with a high silica content. The document discloses that the silica coating of the titanium dioxide particles reduces direct contact with avobenzone, effectively reducing the binding of free titanium with BMDBM.

[0006] CN112190492A discloses an organic-inorganic composite sunscreen cosmetic additive and its preparation method. The preparation process involves mixing nanoporous zinc oxide and avobenzone, then heating and stirring in a vacuum to produce a supported nanoporous zinc oxide. This composite is then dry-ground with nano-titanium dioxide and ethylhexyl methoxycinnamate. Finally, the ground material is mixed with deionized water, carbomer, monoglyceride, and polyoxyethylene fatty acid alcohol ether to produce the composite sunscreen additive. This invention utilizes a method for preparing the supported material to position the avobenzone within the zinc oxide micropores, preventing direct contact between the avobenzone and titanium dioxide, thereby reducing the binding of free titanium with BMDBM.

[0007] CN112545907B discloses a method for preparing wax beads encapsulating a chemical sunscreen and surface-loaded with nano-titanium dioxide, and its use in sunscreen. The method comprises weighing carnauba wax and avobenzone, heating and melting them to obtain an oil phase, weighing unmodified titanium dioxide and dispersing it in water, heating it in a water bath, and dispersing the titanium dioxide to obtain an aqueous phase; then pouring the heated oil phase into the aqueous phase and homogenizing it, causing it to rapidly solidify to form a sunscreen. This invention utilizes a process that places avobenzone in the oil phase and titanium dioxide in the aqueous phase, avoiding direct contact between avobenzone and titanium dioxide and reducing the binding of free titanium with BMDBM.

[0008] The aforementioned literature employs methods such as surface treatment of the titanium dioxide powder raw material, loading avobenzone into the pores of zinc oxide, and adjusting the configuration process to reduce direct contact between avobenzone and titanium dioxide, thereby minimizing the formation of BMDBM-Ti. However, the titanium dioxide surface cannot be completely coated, and exposed free titanium will still be generated, reacting with avobenzone to form BMDBM-Ti. Limited research has been conducted on reducing the binding of free titanium with BMDBM by adding active substances, thereby alleviating the instability of the avobenzone-titanium dioxide system. Therefore, it is necessary to develop a composition to enhance the stability of the avobenzone-titanium dioxide system. Summary of the Invention

[0009] The present invention aims to provide a composition and method for effectively alleviating the reduction of ultraviolet absorbance of an oil dispersion system containing avobenzone and titanium dioxide, wherein caprylyl glycol is used in the composition and method.

[0010] Specifically, the present invention introduces caprylyl glycol into a uniform oil phase system of avobenzone and titanium dioxide, effectively alleviating the problem of reduced ultraviolet absorbance of the system and significantly improving the stability and long-lasting protection ability of the sunscreen system. The present invention is achieved by mixing avobenzone with a portion of oil and fat, and fully stirring under heating conditions to uniformly dissolve the avobenzone in the oil and fat to form a uniform oil phase solution. At the same time, caprylyl glycol, a portion of the oil and fat are mixed with titanium dioxide to fully mix the caprylyl glycol and titanium dioxide to form a uniform caprylyl glycol-titanium dioxide dispersion. Finally, the prepared oil phase solution is mixed with the caprylyl glycol-titanium dioxide dispersion to obtain an avobenzone-titanium dioxide system composition with high stability.

[0011] A first aspect of the present invention provides a method for improving the stability of an avobenzone-titanium dioxide system, the method comprising pretreating titanium dioxide with caprylyl glycol and then mixing the mixture of caprylyl glycol and titanium dioxide with avobenzone.

[0012] In one or more embodiments, the titanium dioxide is pure TiO2 compound particles or titanium dioxide molecular derivatives with surface pretreatment.

[0013] In one or more embodiments, the titanium dioxide has a particle size of nanometers, for example, in the range of 10-100 nm.

[0014] In one or more embodiments, the crystal form of the titanium dioxide is rutile and / or anatase, preferably rutile.

[0015] In one or more embodiments, the surface pretreatment includes a surface modification treatment.

[0016] In one or more embodiments, the surface pretreatment is selected from a combination of one or more of the following pretreatment methods: (1) coating with metal oxides (such as silicon dioxide, aluminum oxide, zinc oxide), silane coupling agents (such as trimethylsilane, polydimethylsiloxane), surfactants (such as stearic acid, polyethylene glycol, acrylate copolymers); (2) wet dispersion treatment, such as using solvent grinding, such as using polyols and silicone oil mixed, and then mechanically grinding to a uniform dispersion; (3) microencapsulation treatment, such as encapsulating titanium dioxide in polymer microcapsules, such as PLGA polymer encapsulation; and (4) non-ionic or surfactant pretreatment, such as using sorbitan stearate or polysorbate-80 to pretreat titanium dioxide particles.

[0017] In one or more embodiments, the step of pre-treating the titanium dioxide surface comprises coating the rutile nano-titanium dioxide with SiO2 / Al2O3, modifying the surface with a silane coupling agent, and then dispersing the surface in silicone oil by wet sand milling.

[0018] In one or more embodiments, in the method, the titanium dioxide is a titanium dioxide product, wherein the mass fraction of the titanium dioxide compound is greater than or equal to 70%, such as 70%-85% or 75-85%.

[0019] In one or more embodiments, the titanium dioxide is one or two of an MT-100TV titanium dioxide product, an ST-15AS titanium dioxide product, an MT-100Z titanium dioxide product, and an STR-100A-LP titanium dioxide product.

[0020] In one or more embodiments, the titanium dioxide product contains 83% titanium dioxide, 9% aluminum hydroxide and 8% stearic acid, or the titanium dioxide product contains 78% titanium dioxide, 6% triethoxycaprylylsilane, 6% aluminum hydroxide and 10% silica, or the titanium dioxide product contains 74% titanium dioxide, 13% aluminum hydroxide and 13% stearic acid, or the titanium dioxide product contains 84% ​​titanium dioxide, 4% hydrogenated polydimethylsiloxane, 4% aluminum hydroxide and 8% hydrated silica.

[0021] In one or more embodiments, the avobenzone-titanium dioxide system further comprises oil.

[0022] In one or more embodiments, the oil comprises one or more of esters, silicone oils, natural oils, and hydrocarbons.

[0023] In one or more embodiments, the esters are selected from one or more of C12-C15 alcohol benzoate, dicaprylyl carbonate, diethylhexyl carbonate, dibutyl adipate, ethylhexyl palmitate, diisopropyl sebacate, isononyl isononanoate, triethylhexyl glycerol, caprylic / capric triglyceride, cetyl hexyl acetate, and mineral oil.

[0024] In one or more embodiments, the silicone oil is selected from one or more of octyl polymethylsiloxane and cyclopentasiloxane.

[0025] In one or more embodiments, the natural oils are selected from one or more of olive oil, coconut oil, and castor oil.

[0026] In one or more embodiments, the hydrocarbons are selected from one or more of isododecane and liquid paraffin.

[0027] In one or more embodiments, the oil comprises one or more of ethylhexyl palmitate, diisopropyl sebacate, and isononyl isononanoate.

[0028] In one or more embodiments, the mass fraction of avobenzone in the avobenzone-titanium dioxide system is 0.05-5.00%, for example, 1.00-5.00%, 1.00-3.00%, 2.00-3.00% or 2.00-5.00%, based on the total weight of the avobenzone-titanium dioxide system.

[0029] In one or more embodiments, in the avobenzone-titanium dioxide system, the mass ratio of caprylyl glycol to titanium dioxide is greater than or equal to 1:10.

[0030] In one or more embodiments, based on the total weight of the avobenzone-titanium dioxide system, the mass fraction of avobenzone is 2.00-5.00%, the mass fraction of oil is 90.00-95.00%, the mass fraction of titanium dioxide is 5.00-10.00%, the mass fraction of caprylyl glycol is 0.5-2.00%, and the mass ratio of caprylyl glycol to titanium dioxide is greater than or equal to 1:10.

[0031] In one or more embodiments, based on the total weight of the avobenzone-titanium dioxide system, the mass fraction of avobenzone is 2.00-5.00%, the mass fraction of oil is 90.00-93.00%, the mass fraction of titanium dioxide is 5.00-10.00%, the mass fraction of caprylyl glycol is 0.5-2.00%, and the mass ratio of caprylyl glycol to titanium dioxide is 1:10-2:5.

[0032] In one or more embodiments, based on the total weight of the avobenzone-titanium dioxide system, the mass fraction of avobenzone is 2.00-5.00%, the mass fraction of oil is 83.00-85.00%, the mass fraction of titanium dioxide is 5.00-10.00%, the mass fraction of caprylyl glycol is 10.00-15.00%, and the mass ratio of caprylyl glycol to titanium dioxide is 1:10-10:5.

[0033] In one or more embodiments, based on the total weight of the avobenzone-titanium dioxide system, the mass fraction of avobenzone is 5.00-10.00%, the mass fraction of oil is 45.00-50.00%, the mass fraction of titanium dioxide is 25.00-30.00%, the mass fraction of caprylyl glycol is 10.00-15.00%, and the mass ratio of caprylyl glycol to titanium dioxide is 1:10-10:25.

[0034] In one or more embodiments, based on the total weight of the avobenzone-titanium dioxide system, the mass fraction of avobenzone is 2.00-5.00%, the mass fraction of oil is 90.00-95.00%, the mass fraction of titanium dioxide is 5.00-10.00%, the mass fraction of caprylyl glycol is 2.00-5.00%, and the mass ratio of caprylyl glycol to titanium dioxide is 1:10-2:5.

[0035] In one or more embodiments, based on the total weight of the avobenzone-titanium dioxide system, the mass fraction of avobenzone is 0.05-2.00%, the mass fraction of oil is 90.00-95.00%, the mass fraction of titanium dioxide is 5.00-10.00%, the mass fraction of caprylyl glycol is 1.00-3.00%, and the mass ratio of caprylyl glycol to titanium dioxide is 1:10-1:5.

[0036] A second aspect of the present invention provides a sunscreen composition, which is prepared by the method described in any embodiment of the first aspect of the present invention.

[0037] In one or more embodiments, the sunscreen composition further comprises one or more of an aqueous phase, a moisturizer, an emulsifier, a pH adjuster, a chelating agent, a preservative, a pigment, a fragrance, and an antioxidant.

[0038] In one or more embodiments, the UV absorbance of the sunscreen composition does not show significant difference after being placed in a 50°C incubator for 2 weeks.

[0039] In one or more embodiments, the sunscreen composition is a lotion, cream, spray, gel, or mask.

[0040] In one or more embodiments, the sunscreen composition is applied to the skin.

[0041] In one or more embodiments, the sunscreen composition is applied to the face, neck, ears, arms, hands (eg, the backs of the hands), legs, chest, back, and / or scalp.

[0042] In some embodiments, after the sunscreen composition is kept at a constant temperature of 50°C for two weeks, the absolute value of the change rate of ultraviolet absorbance at a wavelength of 335-365 nm is less than or equal to 8.5%, preferably less than or equal to 6.0%, and more preferably less than or equal to 3.0%.

[0043] In some embodiments, after the sunscreen composition is kept at a constant temperature of 50° C. for two weeks, the absolute value of the change rate of ultraviolet absorbance at a wavelength of 335-350 nm is less than or equal to 5.0%, preferably less than or equal to 4.8%.

[0044] In a preferred embodiment, after the sunscreen composition is kept at a constant temperature of 50° C. for two weeks, the average absolute value of the change rate of ultraviolet absorbance at a wavelength of 335-365 nm is less than or equal to 3.5%, preferably less than or equal to 3.3%.

[0045] In a preferred embodiment, after the sunscreen composition is kept at a constant temperature of 50° C. for two weeks, the absolute value of the change rate of ultraviolet absorbance at a wavelength of 340 nm is less than 3.5%.

[0046] In an exemplary embodiment, after the sunscreen composition herein is placed at a constant temperature of 50°C for two weeks, the absolute value of the rate of change in ultraviolet absorbance at a wavelength of 335-365 nm is 0.05-8.1%, 0.5-6.5% or 0.5-1.5%, and the average value of the absolute value of the rate of change in ultraviolet absorbance at a wavelength of 335-365 nm is 0.2-3.3% or 0.5-1.5%.

[0047] The third aspect of the present invention provides use of the method according to any embodiment of the first aspect herein in preparing a sunscreen composition and / or in improving the stability of a sunscreen composition.

[0048] In one or more embodiments, the sunscreen composition is a lotion, cream, spray, gel, or mask.

[0049] In one or more embodiments, the sunscreen composition is applied to the skin.

[0050] In one or more embodiments, the sunscreen composition is applied to the face, neck, ears, arms, hands (eg, the backs of the hands), legs, chest, back, and / or scalp.

[0051] In one or more embodiments, the UV absorbance of the sunscreen composition after being placed at 50° C. for two weeks is not significantly different from the initial UV absorbance.

[0052] In some embodiments, after the sunscreen composition is kept at a constant temperature of 50°C for two weeks, the absolute value of the change rate of ultraviolet absorbance at a wavelength of 335-365 nm is less than or equal to 8.5%, preferably less than or equal to 6.0%, and more preferably less than or equal to 3.0%.

[0053] In some embodiments, after the sunscreen composition is kept at a constant temperature of 50° C. for two weeks, the absolute value of the change rate of ultraviolet absorbance at a wavelength of 335-350 nm is less than or equal to 5.0%, preferably less than or equal to 4.8%.

[0054] In a preferred embodiment, after the sunscreen composition is kept at a constant temperature of 50° C. for two weeks, the average absolute value of the change rate of ultraviolet absorbance at a wavelength of 335-365 nm is less than or equal to 3.5%, preferably less than or equal to 3.3%.

[0055] In a preferred embodiment, after the sunscreen composition is kept at a constant temperature of 50° C. for two weeks, the absolute value of the change rate of ultraviolet absorbance at a wavelength of 340 nm is less than 3.5%.

[0056] In an exemplary embodiment, after the sunscreen composition herein is placed at a constant temperature of 50°C for two weeks, the absolute value of the rate of change in ultraviolet absorbance at a wavelength of 335-365 nm is 0.05-8.1%, 0.5-6.5% or 0.5-1.5%, and the average value of the absolute value of the rate of change in ultraviolet absorbance at a wavelength of 335-365 nm is 0.2-3.3% or 0.5-1.5%.

[0057] In some embodiments, the stability is high temperature stability, such as above 35°C, preferably above 50°C. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 The structural formula is BMDBM-Ti.

[0059] Figure 2 This is the ultraviolet absorption curve of caprylyl glycol.

[0060] Figure 3 The two-week stability test results for Examples 1 to 4 are shown in the figure below. The left column shows the UV absorption curves of the initial value and the value after two weeks, and the right column shows the significant difference between the initial value and the value after two weeks. Rows (a) to (d) are for Examples 1 to 4, respectively.

[0061] Figure 4 The two-week stability test results for Examples 5 to 7 are shown in the figure below. The left column shows the UV absorption curves of the initial value and the value after two weeks, and the right column shows the significant difference between the initial value and the value after two weeks. Rows (a) to (c) show Examples 5 to 7, respectively.

[0062] Figure 5 The two-week stability test results for Comparative Examples 1 to 4 are shown in the left column. The UV absorption curves for the initial value and the two-week period are shown, and the graph of significant differences between the initial value and the two-week period is shown in the right column. Rows (a) to (d) represent Comparative Examples 1 to 4, respectively.

[0063] Figure 6 The two-week stability test results for Comparative Examples 5 to 8 are shown in the figure below. The left column shows the UV absorption curves of the initial value and the value after 2 weeks, and the right column shows the significant difference between the initial value and the value after 2 weeks. Rows (a) to (d) are for Comparative Examples 5 to 8, respectively. DETAILED DESCRIPTION

[0064] To facilitate understanding of the features and effects of the present invention by those skilled in the art, the following provides a general description and definition of the terms and expressions used in the specification and claims. Unless otherwise indicated, all technical and scientific terms used herein have the ordinary meanings as understood by those skilled in the art regarding the present invention. In the event of conflict, the definitions in this specification shall prevail.

[0065] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, that is, the present invention can be implemented without being limited by any specific theory or mechanism.

[0066] Herein, “comprising,” “including,” “containing” and similar terms encompass the meanings of “consisting essentially of” and “consisting of,” for example, when “A comprises B and C” is disclosed herein, “A consists essentially of B and C” and “A consists of B and C” should be deemed to have been disclosed herein.

[0067] Throughout this document, all features, such as values, amounts, amounts, and concentrations, specified in numerical ranges or percentage ranges are provided for simplicity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to encompass and specifically disclose all possible subranges and individual values ​​within those ranges (including integers and fractions).

[0068] In this document, unless otherwise specified, percentage refers to mass percentage and ratio refers to mass ratio.

[0069] Herein, the sum of the percentages of the various components of the composition is 100%.

[0070] Herein, when describing embodiments or examples, it should be understood that they are not intended to limit the present invention to these embodiments or examples. On the contrary, all alternatives, modifications and equivalents of the methods and materials described herein are encompassed within the scope defined by the claims.

[0071] In this document, for the sake of brevity, not all possible combinations of the various technical features in each embodiment or example are described. Therefore, as long as there are no contradictions in the combination of these technical features, the various technical features in each embodiment or example can be combined in any way, and all possible combinations should be considered to be within the scope of this specification.

[0072] In this article, "pretreatment" refers to the steps of preliminary treatment of raw materials before the main processing or operation.

[0073] The instability of the avobenzone-titanium dioxide system is caused by the formation of a complex, BMDBM-Ti, between the free titanium ions in the titanium dioxide and avobenzone. This results in a decrease in the system's absorbance after two weeks at 50°C, weakening its sunscreen effectiveness. This study discovered that the addition of caprylyl glycol stabilized the absorbance after two weeks at 50°C. The inventors hypothesize that the hydroxyl group, a common electron-donating group, exhibits a charge-absorbing effect with the free titanium ions in the system, leading to competitive inhibition with avobenzone, reducing the formation of BMDBM-Ti and thus maintaining the sunscreen's effectiveness. This led to the present invention.

[0074] Method for improving the stability of avobenzone-titanium dioxide system

[0075] The method for improving the stability of the avobenzone-titanium dioxide system of the present invention comprises pretreating titanium dioxide with octyl glycol and then mixing the mixture of octyl glycol and titanium dioxide with avobenzone.

[0076] In the method herein, the step of pre-treating titanium dioxide with caprylyl glycol includes first contacting caprylyl glycol with titanium dioxide, for example, adding titanium dioxide to caprylyl glycol, or adding caprylyl glycol to titanium dioxide and mixing them uniformly.

[0077] Herein, titanium dioxide can be a titanium dioxide product commonly used in sunscreen compositions, and can be pure TiO2 compound particles or surface-pretreated titanium dioxide molecular derivatives. Herein, the titanium dioxide particle size is nanometer-scale, for example, in the range of 10-100 nm or 20-100 nm. Herein, the titanium dioxide crystalline form can be rutile and / or anatase, preferably rutile. Herein, titanium dioxide molecular derivatives refer to derivatives obtained from titanium dioxide particles after undergoing specific processes and surface pretreatment. This pretreatment can improve the dispersibility of the titanium dioxide particles, enhance their UV shielding effectiveness, and enhance skin feel and stability. Generally, the pretreatment method may include surface modification treatment, including but not limited to one or more combinations of the following pretreatment methods: (1) coating with metal oxides (such as silicon dioxide, aluminum oxide, zinc oxide, etc.), silane coupling agents (such as trimethylsilane, polydimethylsiloxane), surfactants (stearic acid, polyethylene glycol, acrylate copolymers, etc.); (2) wet dispersion treatment, such as using solvent grinding, such as using a mixture of polyols and silicone oil, and then mechanically grinding to a uniform dispersion; (3) microencapsulation treatment, such as encapsulating titanium dioxide in polymer microcapsules, such as PLGA polymer encapsulation; (4) non-ionic or surfactant pretreatment, such as using sorbitan stearate, polysorbate-80, etc. to pretreat titanium dioxide particles. It should be understood that the titanium dioxide particles used in the present invention can be a mixture of any two or more of the above titanium dioxide particles.

[0078] In some embodiments, the surface pre-treated titanium dioxide comprises coating the surface of rutile nano-titanium dioxide with SiO2 / Al2O3, modifying the surface with a silane coupling agent, and then dispersing the surface in silicone oil by wet sand milling.

[0079] In some embodiments, conventional titanium dioxide products in the art are used, and the mass fraction of the titanium dioxide compound in the product is generally greater than or equal to 70%, for example, 70%-85% or 75-85%. In an exemplary embodiment, the titanium dioxide herein is one or two of MT-100TV titanium dioxide products (manufactured by TAYCA CORPORATION), ST-15AS titanium dioxide products (manufactured by Changzhou Naou New Material Technology Co., Ltd.), MT-100Z titanium dioxide products (manufactured by TAYCA CORPORATION), and STR-100A-LP titanium dioxide products (manufactured by SAKAI CHEMICALINDUSTRIAL CO., LTD). Among them, based on the total weight of the product, the MT-100TV titanium dioxide product contains 83% titanium dioxide, 9% aluminum hydroxide and 8% stearic acid, the ST-15AS titanium dioxide product contains 78% titanium dioxide, 6% triethoxycaprylylsilane, 6% aluminum hydroxide and 10% silica, the MT-100Z titanium dioxide product contains 74% titanium dioxide, 13% aluminum hydroxide, 13% stearic acid, and the STR-100A-LP titanium dioxide product contains 84% ​​titanium dioxide, 4% hydrogenated polydimethylsiloxane, 4% aluminum hydroxide and 8% hydrated silica.

[0080] Avobenzone-titanium dioxide system usually also contains oils and fats. The oils and fats can be commonly used in avobenzone-titanium dioxide system, such as esters, silicone oils, natural oils and fats, hydrocarbons, etc. Esters can include but are not limited to C12-C15 alcohol benzoate, dicaprylyl carbonate, diethylhexyl carbonate, dibutyl adipate, ethylhexyl palmitate, diisopropyl sebacate, isononyl isononanoate, triethylhexyl glycerol, caprylic / capric triglyceride, cetyl acetate, mineral oil, silicone oils can include but are not limited to octyl polymethylsiloxane, cyclopentasiloxane, natural oils and fats can include but are not limited to olive oil, coconut oil and castor oil, hydrocarbons can include but are not limited to isododecane, liquid paraffin. In an exemplary embodiment, in the method herein, the oils and fats include but are not limited to one or more of ethylhexyl palmitate, diisopropyl sebacate, and isononyl isononanoate. The oils and fats can be heated (e.g., 80-95°C) to mix the oils and fats with other ingredients or between different oils.

[0081] In the method herein, there is no particular restriction on the order of adding titanium dioxide, caprylyl glycol and oil, as long as the three are mixed evenly. Titanium dioxide, caprylyl glycol and part of the oil (for example, 15-50% of the total mass of the oil in the system) can be mixed first, heated to 35-40°C to mix evenly, and then avobenzone and the remaining oil are added. In an exemplary embodiment, the method further includes the step of heating avobenzone and the remaining oil to 85-90°C to mix evenly before adding avobenzone to the oil system. There are no special requirements for the mass distribution of the part of the oil added first and the remaining oil in the oil system, as long as the former can completely disperse the titanium dioxide and caprylyl glycol (titanium dioxide powder cannot be dissolved and can only be dispersed with titanium dioxide), and the latter can completely dissolve avobenzone.

[0082] In the avobenzone-titanium dioxide system of this invention, the mass fraction of avobenzone can be 0.05-5.00%, for example, 1.00-5.00%, 1.00-3.00%, 2.00-3.00% or 2.00-5.00%, based on the total weight of the avobenzone-titanium dioxide system; in this system, the mass ratio of caprylyl glycol to titanium dioxide can be greater than or equal to 1:10, for example, 0.5:5, 2:5, 5:1, 10:5, 10:25, or 1:5.

[0083] In some embodiments, based on the total weight of the avobenzone-titanium dioxide system, the mass fraction of titanium dioxide can be 5.0-25.0%, for example, 5.00-25.00%, 5.00-20.00%, 5.00-15.00%, 10.00-15.00% or 20-25%, and / or the mass fraction of caprylyl glycol can be 0.5-10.0%, for example, 0.50-10.00%, 0.50-1.00%, 1.00-10.00%, 2.00-10.00% or 2.00-5.00%, and / or in the system, the mass ratio of caprylyl glycol to titanium dioxide can be greater than or equal to 1:10, for example, 0.5:5, 2:5, 5:1, 10:5, 10:25, or 1:5.

[0084] In some embodiments, the mass fraction of titanium dioxide can be 5.0-25.0%, such as 5.00-25.00%, 5.00-10.00%, 20.00-25.00%, or 15.00-20.00%, based on the total weight of the avobenzone-titanium dioxide system.

[0085] In an exemplary embodiment, based on the total weight of the avobenzone-titanium dioxide system, the mass fraction of avobenzone can be 2.00-5.00%, the mass fraction of oil can be 90.00-95.00%, the mass fraction of titanium dioxide can be 5.00-10.00%, the mass fraction of caprylyl glycol can be 0.5-2.00%, and the mass ratio of caprylyl glycol to titanium dioxide is greater than or equal to 1:10.

[0086] In an exemplary embodiment, based on the total weight of the avobenzone-titanium dioxide system, the mass fraction of avobenzone can be 2.00-5.00%, the mass fraction of oil can be 90.00-93.00%, the mass fraction of titanium dioxide can be 5.00-10.00%, the mass fraction of caprylyl glycol can be 0.5-2.00%, and the mass ratio of caprylyl glycol to titanium dioxide is 1:10-2:5.

[0087] In an exemplary embodiment, based on the total weight of the avobenzone-titanium dioxide system, the mass fraction of avobenzone can be 2.00-5.00%, the mass fraction of oil can be 83.00-85.00%, the mass fraction of titanium dioxide can be 5.00-10.00%, the mass fraction of caprylyl glycol can be 10.00-15.00%, and the mass ratio of caprylyl glycol to titanium dioxide is 1:10-10:5.

[0088] In an exemplary embodiment, based on the total weight of the avobenzone-titanium dioxide system, the mass fraction of avobenzone can be 5.00-10.00%, the mass fraction of oil can be 45.00-50.00%, the mass fraction of titanium dioxide can be 25.00-30.00%, the mass fraction of caprylyl glycol can be 10.00-15.00%, and the mass ratio of caprylyl glycol to titanium dioxide is 1:10-10:25.

[0089] In an exemplary embodiment, based on the total weight of the avobenzone-titanium dioxide system, the mass fraction of avobenzone can be 2.00-5.00%, the mass fraction of oil can be 90.00-95.00%, the mass fraction of titanium dioxide can be 5.00-10.00%, the mass fraction of caprylyl glycol can be 2.00-5.00%, and the mass ratio of caprylyl glycol to titanium dioxide is 1:10-2:5.

[0090] In an exemplary embodiment, based on the total weight of the avobenzone-titanium dioxide system, the mass fraction of avobenzone can be 0.05-2.00%, the mass fraction of oil can be 90.00-95.00%, the mass fraction of titanium dioxide can be 5.00-10.00%, the mass fraction of caprylyl glycol can be 1.00-3.00%, and the mass ratio of caprylyl glycol to titanium dioxide is 1:10-1:5.

[0091] In some embodiments, the present invention also provides a method for preparing a sunscreen composition containing an avobenzone-titanium dioxide system, which comprises the steps of first contacting titanium dioxide and caprylyl glycol in an oil system, and then adding avobenzone.

[0092] In some embodiments, the method herein comprises the steps of first adding titanium dioxide and caprylyl glycol, optionally adding part or all of the oil, and then adding avobenzone and the remaining oil. In some embodiments, avobenzone and the remaining oil can be mixed uniformly before adding to the system.

[0093] Sunscreen composition

[0094] The avobenzone-titanium dioxide system prepared using the method described in any embodiment herein can be used to prepare a sunscreen composition. After being held at 50°C for two weeks, the UV absorbance at 280-420 nm of the sunscreen composition is not significantly different from that of the composition two weeks prior. To avoid exceeding the upper detection limit of the instrument (to ensure data reliability, the absorbance response Abs must be below 2, so the sample needs to be diluted according to actual conditions), the sunscreen composition can be diluted, for example, 10,000-fold.

[0095] Therefore, the present invention also provides a sunscreen composition, which is prepared by the method according to any embodiment of the present invention.

[0096] The sunscreen composition herein may optionally further contain one or more of an aqueous phase, a moisturizer, an emulsifier, a pH adjuster, a chelating agent, a preservative, a pigment, a flavor, and an antioxidant. Moisturizers may include glycerin, hyaluronic acid, butylene glycol, vitamin B5, etc.; emulsifiers may include Tween 60, Span 60, sodium stearate, lecithin, etc.; pH adjusters may include citric acid / sodium citrate, triethanolamine, lactic acid / sodium lactate, etc.; chelating agents may include disodium EDTA, citric acid, etc.; preservatives may include methylparaben, phenoxyethanol, 1,2-hexanediol, etc.; pigments may include iron oxide, etc.; flavors may include rose extract, citrus essential oil, etc.; antioxidants may include vitamin E, coenzyme Q10, ascorbic acid, tea polyphenols, rosemary extract, etc.

[0097] In some embodiments, after the sunscreen composition is kept at a constant temperature of 50°C for two weeks, the absolute value of the change rate of ultraviolet absorbance at a wavelength of 335-365 nm is less than or equal to 8.5%, preferably less than or equal to 6.0%, and more preferably less than or equal to 3.0%.

[0098] In some embodiments, after the sunscreen composition is kept at a constant temperature of 50° C. for two weeks, the absolute value of the change rate of ultraviolet absorbance at a wavelength of 335-350 nm is less than or equal to 5.0%, preferably less than or equal to 4.8%.

[0099] In a preferred embodiment, after the sunscreen composition is kept at a constant temperature of 50° C. for two weeks, the average absolute value of the change rate of ultraviolet absorbance at a wavelength of 335-365 nm is less than or equal to 3.5%, preferably less than or equal to 3.3%.

[0100] In a preferred embodiment, after the sunscreen composition is kept at a constant temperature of 50° C. for two weeks, the absolute value of the change rate of ultraviolet absorbance at a wavelength of 340 nm is less than 3.5%.

[0101] In an exemplary embodiment, after the sunscreen composition herein is placed at a constant temperature of 50°C for two weeks, the absolute value of the rate of change in ultraviolet absorbance at a wavelength of 335-365 nm is 0.05-8.1%, 0.5-6.5% or 0.5-1.5%, and the average value of the absolute value of the rate of change in ultraviolet absorbance at a wavelength of 335-365 nm is 0.2-3.3% or 0.5-1.5%.

[0102] application

[0103] The present invention also provides the use of a method according to any embodiment herein for preparing a sunscreen composition and / or improving the stability of a sunscreen composition. In preferred embodiments, the stability is high-temperature stability (e.g., above 35°C), such as stability in an extremely high-temperature environment (50°C or higher). In some embodiments, the UV absorbance of the sunscreen composition after being exposed to 50°C for two weeks is not significantly different from the initial UV absorbance.

[0104] The sunscreen composition herein may be in the form commonly used in the art, such as emulsion, cream, spray, gel, mask, etc.

[0105] The sunscreen composition herein can be applied to human skin, including but not limited to the face, neck, ears, arms, hands (such as the back of the hands), legs, chest, back, scalp, etc.

[0106] The present invention has the following beneficial effects:

[0107] The key technical point of the present invention is that caprylyl glycol is brought into contact with titanium dioxide in advance, which results in competitive inhibition with the subsequently added avobenzone, thereby reducing the production of BMDBM-Ti and stably maintaining the sun protection ability of the sunscreen in the system.

[0108] The present invention will be further described below by way of specific examples. It should be understood that these examples are merely illustrative and are not intended to limit the scope of the present invention. The methods and reagents used in the examples are, unless otherwise stated, conventional methods and reagents in the art.

[0109] Calculation method of absorption peak intensity

[0110] The initial UV absorbance was tested, and then placed in a 50°C constant temperature box for 2 weeks, and the UV absorbance after 2 weeks was tested.

[0111] Test method: Dilute the prepared sample 10,000-fold with solvent, take an appropriate amount of sample, and scan with an Agilent Cary 60 UV-Vis spectrophotometer within the wavelength range of 280-420 nm to obtain the UV absorption value.

[0112] The calculation formula for the absorption peak intensity (A) is:

[0113] A = lg(1 / T) = kCL (1)

[0114] Where, T: transmittance; k: molar absorption coefficient, unit: L·cm -1 ·mol-1; C: concentration (mol / L); L: optical path length (cm).

[0115] The k value is constant, L is the thickness of the cuvette used in the experiment, and the constant value remains unchanged, so the size of the A value can determine the difference in concentration C. Figure 2 As shown, caprylyl glycol has no ultraviolet absorption in the ultraviolet band of 280-420nm. Therefore, the intensity of the absorption peak can be used as a basis for the content of the ultraviolet absorber avobenzone and titanium dioxide.

[0116] Avobenzone's UV absorption peak in the UV wavelength range of 280-420 nm is located near 350 nm. To assess data validity, seven data points were selected at wavelengths of 335 nm, 340 nm, 345 nm, 350 nm, 355 nm, 360 nm, and 365 nm. Statistical analysis was used to determine if there was a significant difference between the pre- and post-experimental data. The Shapiro-Wilk test was used to test the significance of the differences between the two groups for normal distribution, with a two-sided sig. > 0.05. If the test data were normally distributed, a paired t-test was used for statistical analysis. If the test data were non-normally distributed, a paired rank-sum test was used for statistical analysis. Two-tailed tests were used for statistical analysis, with an α level of 0.05. Absorption peak intensity (A) results are expressed as Mean ± SE. P < 0.05 indicates a statistically significant difference, with a value of *; P < 0.01 indicates a statistically significant difference, with a value of **; and P < 0.001 indicates an extremely significant difference, with a value of ***.

[0117] Source of raw materials

[0118] Avobenzone, DSM Nutritional Products Ltd.

[0119] Ethylhexyl palmitate, Baida Fine Chemical Co., Ltd.

[0120] Sebacic acid / diisopropyl ester, Lubrizol Advanced Materials, Inc

[0121] Isononyl Isononanoate, Baida Fine Chemical Co., Ltd.

[0122] MT-100TV titanium dioxide, TAYCA CORPORATION

[0123] ST-15AS titanium dioxide, manufactured by Changzhou Naou New Material Technology Co., Ltd.

[0124] Caprylyl glycol, INOLEX, lnc.

[0125] Glycerin, PROCTER&GAMBLE INTERNATIONAL OPERATIONS SA SINGAPORE BRANCH

[0126] Butanediol, DAICEL CORPORATION

[0127] Examples 1-7

[0128] The preparation method of the avobenzone-titanium dioxide system of Examples 1-7 comprises: (1) heating caprylyl glycol, titanium dioxide, and a small amount of oil to 35-40°C and stirring to mix uniformly; (2) heating avobenzone and the remaining oil to 85-90°C to dissolve uniformly and then adding the mixture to the system. Specific ingredients and contents are shown in Table 1 below, and the preparation method is shown in Table 2.

[0129] Table 1: Example formulations

[0130]

[0131] Table 2: Preparation method

[0132]

[0133]

[0134] The initial UV absorption value of the composition prepared in Example 1-7 was tested, and then placed in a 50°C constant temperature box for 2 weeks. The UV absorbance after 2 weeks was tested to obtain a UV absorption curve of the initial value and the UV absorption curve after 2 weeks. Seven data points at wavelengths of 335nm, 340nm, 345nm, 350nm, 355nm, 360nm, and 365nm were selected. Statistics were used to determine whether there was a significant difference between the initial value and the data after 2 weeks. A significant difference graph between the initial value and the data after 2 weeks was obtained. The results are shown in FIG. Figures 3 to 4 .

[0135] Comparative Examples 1-8

[0136] Comparative Examples 1-8 were prepared using the formula in Table 3. The preparation method of Comparative Examples 1-7 was the same as that of Example 1. The preparation method of Comparative Example 8 was as follows: titanium dioxide and a small amount of oil (15% of the total weight of the oil) were stirred at 35°C and mixed evenly, then avobenzone and the remaining oil (85% of the total weight of the oil) were heated at 90°C and dissolved evenly, and then added, and finally caprylyl glycol was added.

[0137] Table 3: Comparative Example Formulation

[0138]

[0139]

[0140] The initial ultraviolet absorption value of the composition prepared in Comparative Examples 1-8 was tested, and then placed in a constant temperature box at 50°C for 2 weeks. The ultraviolet absorbance after 2 weeks was tested to obtain an initial value and an ultraviolet absorption curve after 2 weeks. Seven data points at wavelengths of 335nm, 340nm, 345nm, 350nm, 355nm, 360nm, and 365nm were selected. The specific values ​​are shown in Tables 4-7 below. Statistics were used to determine whether there was a significant difference between the initial value and the data after 2 weeks. A significant difference graph between the initial value and the data after 2 weeks was obtained. The results are shown in Tables 4-7. Figures 5 to 6 .

[0141] Table 4: UV absorbance of the examples (initial value and after 2 weeks)

[0142]

[0143] Table 5: UV absorbance of the examples (initial value and after 2 weeks)

[0144]

[0145]

[0146] Table 6: UV absorbance of comparative example (initial value and after 2 weeks)

[0147]

[0148] Table 7: Comparative Example UV absorbance (initial value and after 2 weeks)

[0149]

[0150] It can be seen from the various embodiments and comparative examples of this application that:

[0151] (1) It can be seen from Examples 1, 2, and 3 and Comparative Example 1 that in the case of ethylhexyl palmitate and MT-100TV titanium dioxide, the change in the absorbance curve and the significance analysis show that the ultraviolet absorbance is stably maintained by the addition of caprylyl glycol.

[0152] (2) Compared with Comparative Example 2, in Example 4, in the system of 5% avobenzone and 25% MT-100TV titanium dioxide in diisopropyl sebacate, the addition of 10% octyl glycol effectively alleviated the decrease in ultraviolet absorbance.

[0153] (3) Example 5 Compared with Comparative Example 3, in the titanium dioxide of ST-15AS, the change in the absorbance curve and the significance analysis show that the ultraviolet absorbance is stably maintained by the addition of octyl glycol.

[0154] (4) It can be seen from Example 6 and Comparative Example 4 that in the oil isononyl isononanoate, the change in the absorbance curve and the significance analysis show that the ultraviolet absorbance is stably maintained by the addition of octyl glycol.

[0155] (5) It can be seen from Comparative Example 5 and Example 1 that the ratio of the addition amount of octyl glycol to MT-100TV in Comparative Example 5 is 1 / 100, and the absorbance curve of the system decreases after 2 weeks, while the ratio of the addition amount of octyl glycol to MT-100TV in Example 1 is 1 / 10, and the absorbance of the system remains stable after 2 weeks.

[0156] (6) As shown in Example 7, when avobenzone is added in an amount of 0.05%, the change in the absorbance curve and the significance analysis show that the ultraviolet absorbance is stably maintained by the addition of caprylyl glycol.

[0157] (7) Comparative Examples 6 and 7 show that when other alcohols such as polyol glycerol and butylene glycol are used, the initial value and the UV absorbance after 2 weeks are significantly different, and the system cannot be maintained stable.

[0158] (8) Comparative Example 8 shows that caprylyl glycol was not in contact with titanium dioxide in advance, and the initial value and the ultraviolet absorbance after 2 weeks were significantly different, and the system could not be maintained stable.

Claims

1. A method for improving the stability of an avobenzone-titanium dioxide system, characterized in that: The method comprises pre-treating titanium dioxide with caprylyl glycol and then mixing the mixture of caprylyl glycol and titanium dioxide with avobenzone.

2. The method according to claim 1, wherein The titanium dioxide is pure TiO2 compound particles or titanium dioxide molecular derivatives with surface pretreatment. Preferably, the particle size of the titanium dioxide is nanometer-sized, for example, in the range of 10-100 nm; Preferably, the crystal form of the titanium dioxide is rutile and / or anatase, preferably rutile.

3. The method according to claim 2, wherein The surface pretreatment includes surface modification treatment, preferably selected from one or more combinations of the following pretreatment methods: (1) Coating with metal oxides (such as silicon dioxide, aluminum oxide, zinc oxide), silane coupling agents (such as trimethylsilane, polydimethylsiloxane), and surfactants (such as stearic acid, polyethylene glycol, and acrylate copolymers); (2) Wet dispersion treatment, such as using solvent grinding, such as using a mixture of polyol and silicone oil, and then mechanically grinding to a uniform dispersion; (3) microencapsulation, such as encapsulating titanium dioxide in polymer microcapsules, such as PLGA polymer encapsulation; and (4) Non-ionic or surfactant pretreatment, such as using sorbitan stearate or polysorbate 80 to pretreat titanium dioxide particles; Preferably, the step of pre-treating the titanium dioxide surface comprises coating the rutile nano-titanium dioxide with SiO2 / Al2O3, modifying the surface with a silane coupling agent, and then dispersing the surface in silicone oil by wet sand milling.

4. The method according to any one of claims 1 to 3, wherein In the method, the titanium dioxide is a titanium dioxide product, wherein the mass fraction of the titanium dioxide compound is greater than or equal to 70%, such as 70%-85% or 75-85%; Preferably, the titanium dioxide is one or two of MT-100TV titanium dioxide product, ST-15AS titanium dioxide product, MT-100Z titanium dioxide product and STR-100A-LP titanium dioxide product; Preferably, the titanium dioxide product contains 83% titanium dioxide, 9% aluminum hydroxide and 8% stearic acid, or the titanium dioxide product contains 78% titanium dioxide, 6% triethoxyoctylsilane, 6% aluminum hydroxide and 10% silica, or the titanium dioxide product contains 74% titanium dioxide, 13% aluminum hydroxide and 13% stearic acid, or the titanium dioxide product contains 84% ​​titanium dioxide, 4% hydrogenated polydimethylsiloxane, 4% aluminum hydroxide and 8% hydrated silica.

5. The method according to any one of claims 1 to 4, wherein The avobenzone-titanium dioxide system also contains oil; Preferably, the oil comprises one or more of esters, silicone oils, natural oils, and hydrocarbons; Preferably, the esters are selected from one or more of C12-C15 alcohol benzoate, dicaprylyl carbonate, diethylhexyl carbonate, dibutyl adipate, ethylhexyl palmitate, diisopropyl sebacate, isononyl isononanoate, triethylhexyl glycerol, caprylic / capric triglyceride, cetyl hexyl acetate, and mineral oil; Preferably, the silicone oil is selected from one or more of octyl polymethylsiloxane and cyclopentasiloxane; Preferably, the natural oils are selected from one or more of olive oil, coconut oil and castor oil; Preferably, the hydrocarbon is selected from one or more of isododecane and liquid paraffin; Preferably, the oil comprises one or more of ethylhexyl palmitate, diisopropyl sebacate, and isononyl isononanoate.

6. The method according to any one of claims 1 to 5, characterized in that: In the avobenzone-titanium dioxide system, the mass fraction of avobenzone is 0.05-5.00%, for example, 1.00-5.00%, 1.00-3.00%, 2.00-3.00% or 2.00-5.00%, based on the total weight of the avobenzone-titanium dioxide system; and / or In the avobenzone-titanium dioxide system, the mass ratio of caprylyl glycol to titanium dioxide is greater than or equal to 1:

10.

7. The method according to any one of claims 1 to 6, wherein: Based on the total weight of the avobenzone-titanium dioxide system, the mass fraction of avobenzone is 2.00-5.00%, the mass fraction of oil is 90.00-95.00%, the mass fraction of titanium dioxide is 5.00-10.00%, the mass fraction of caprylyl glycol is 0.5-2.00%, and the mass ratio of caprylyl glycol to titanium dioxide is greater than or equal to 1:10; or Based on the total weight of the avobenzone-titanium dioxide system, the mass fraction of avobenzone is 2.00-5.00%, the mass fraction of oil is 90.00-93.00%, the mass fraction of titanium dioxide is 5.00-10.00%, the mass fraction of caprylyl glycol is 0.5-2.00%, and the mass ratio of caprylyl glycol to titanium dioxide is 1:10-2:5; or Based on the total weight of the avobenzone-titanium dioxide system, the mass fraction of avobenzone is 2.00-5.00%, the mass fraction of oil is 83.00-85.00%, the mass fraction of titanium dioxide is 5.00-10.00%, the mass fraction of caprylyl glycol is 10.00-15.00%, and the mass ratio of caprylyl glycol to titanium dioxide is 1:10-10:5; or Based on the total weight of the avobenzone-titanium dioxide system, the mass fraction of avobenzone is 5.00-10.00%, the mass fraction of oil is 45.00-50.00%, the mass fraction of titanium dioxide is 25.00-30.00%, the mass fraction of caprylyl glycol is 10.00-15.00%, and the mass ratio of caprylyl glycol to titanium dioxide is 1:10-10:25; or Based on the total weight of the avobenzone-titanium dioxide system, the mass fraction of avobenzone is 2.00-5.00%, the mass fraction of oil is 90.00-95.00%, the mass fraction of titanium dioxide is 5.00-10.00%, the mass fraction of caprylyl glycol is 2.00-5.00%, and the mass ratio of caprylyl glycol to titanium dioxide is 1:10-2:5; or Based on the total weight of the avobenzone-titanium dioxide system, the mass fraction of avobenzone is 0.05-2.00%, the mass fraction of oil is 90.00-95.00%, the mass fraction of titanium dioxide is 5.00-10.00%, the mass fraction of caprylyl glycol is 1.00-3.00%, and the mass ratio of caprylyl glycol to titanium dioxide is 1:10-1:

5.

8. A sunscreen composition, characterized in that The sunscreen composition is prepared by the method according to any one of claims 1 to 7; Optionally, the sunscreen composition further contains one or more of an aqueous phase, a moisturizer, an emulsifier, a pH adjuster, a chelating agent, a preservative, a pigment, a fragrance, and an antioxidant; Preferably, the UV absorbance of the sunscreen composition after being placed at 50° C. for two weeks is not significantly different from the initial UV absorbance; Preferably, after the sunscreen composition is kept at a constant temperature of 50° C. for two weeks, the absolute value of the change rate of ultraviolet absorbance at a wavelength of 335-365 nm is less than or equal to 8.5%, preferably less than or equal to 6.0%, more preferably less than or equal to 3.0%; Preferably, after the sunscreen composition is kept at a constant temperature of 50° C. for two weeks, the absolute value of the change rate of ultraviolet absorbance at a wavelength of 335-350 nm is less than or equal to 5.0%, preferably less than or equal to 4.8%; Preferably, after the sunscreen composition is kept at a constant temperature of 50° C. for two weeks, the average absolute value of the change rate of ultraviolet absorbance at a wavelength of 335-365 nm is less than or equal to 3.5%, preferably less than or equal to 3.3%; Preferably, after the sunscreen composition is kept at a constant temperature of 50° C. for two weeks, the absolute value of the change rate of ultraviolet absorbance at a wavelength of 340 nm is less than 3.5%; Preferably, after the sunscreen composition is placed at a constant temperature of 50°C for two weeks, the absolute value of the change rate of ultraviolet absorbance at a wavelength of 335-365nm is 0.05-8.1%, 0.5-6.5% or 0.5-1.5%, and the average value of the absolute value of the change rate of ultraviolet absorbance at a wavelength of 335-365nm is 0.2-3.3% or 0.5-1.5%.

9. The sunscreen composition according to claim 8, wherein The sunscreen composition is a lotion, cream, spray, gel or mask; Preferably, the sunscreen composition is applied to the skin, for example, the face, neck, ears, arms, hands (such as the back of the hands), legs, chest, back, scalp.

10. Use of the method according to any one of claims 1 to 7 in preparing a sunscreen composition and / or in improving the stability of a sunscreen composition; Preferably, the sunscreen composition is a lotion, cream, spray, gel or mask; Preferably, the sunscreen composition is applied to the skin, such as the face, neck, ears, arms, hands (such as the back of the hands), legs, chest, back, and scalp; Preferably, the UV absorbance of the sunscreen composition after being placed at 50° C. for two weeks is not significantly different from the initial UV absorbance; Preferably, after the sunscreen composition is kept at a constant temperature of 50° C. for two weeks, the absolute value of the change rate of ultraviolet absorbance at a wavelength of 335-365 nm is less than or equal to 8.5%, preferably less than or equal to 6.0%, more preferably less than or equal to 3.0%; Preferably, after the sunscreen composition is kept at a constant temperature of 50° C. for two weeks, the absolute value of the change rate of ultraviolet absorbance at a wavelength of 335-350 nm is less than or equal to 5.0%, preferably less than or equal to 4.8%; Preferably, after the sunscreen composition is kept at a constant temperature of 50° C. for two weeks, the average absolute value of the change rate of ultraviolet absorbance at a wavelength of 335-365 nm is less than or equal to 3.5%, preferably less than or equal to 3.3%; Preferably, after the sunscreen composition is kept at a constant temperature of 50° C. for two weeks, the absolute value of the change rate of ultraviolet absorbance at a wavelength of 340 nm is less than 3.5%; Preferably, after the sunscreen composition is placed at a constant temperature of 50° C. for two weeks, the absolute value of the rate of change of ultraviolet absorbance at a wavelength of 335-365 nm is 0.05-8.1%, 0.5-6.5% or 0.5-1.5%, and the average value of the absolute value of the rate of change of ultraviolet absorbance at a wavelength of 335-365 nm is 0.2-3.3% or 0.5-1.5%; Preferably, the stability is high temperature stability, such as above 35°C, preferably above 50°C.

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