A sunscreen composition with excellent photostability

Abstract

The application discloses a sunscreen composition with excellent light stability. The sunscreen composition contains the following components in parts by mass: 4-14 parts of ethylhexyl methoxycinnamate, 1-5 parts of butyl methoxydibenzoylmethane, 0.1-8 parts of octocrylene, and 0.1-5 parts of bis-ethylhexyloxyphenol methoxyphenyl triazine. The sunscreen composition has raw materials that are easy to obtain and simple preparation process, can provide more durable and broad-spectrum ultraviolet protection effect for sunscreen cosmetics, and has extremely high market application prospect.

Description

Technical Field

[0001] This invention relates to the field of cosmetics, and in particular to a sunscreen composition with excellent photostability. Background Technology

[0002] Ultraviolet (UV) radiation can be classified into long-wave UVA (320-400 nm) and medium-wave UVB (280-320 nm) based on wavelength. UVB easily causes acute photodamage such as skin redness and sunburn, while UVA can penetrate deep into the epidermis, inducing photoaging and abnormal pigmentation, and in severe cases, even increasing the risk of skin lesions. Therefore, developing high-performance sunscreens is of great practical significance for skin protection. To achieve broad-spectrum and highly effective sun protection, formulations often combine two or more UV absorbers, utilizing the synergistic effect between components to broaden the UV absorption band, enhance protective efficacy, and simultaneously improve the overall performance and photostable properties of the sunscreen system.

[0003] Butyl methoxydibenzoylmethane (AVB, avobenzone) is currently the most widely used and highly effective UVA absorber, while ethylhexyl methoxycinnamate (OMC, octyl p-methoxycinnamate) is a classic and highly effective UVB sunscreen. The combination of these two can achieve full-band UVA-UVB coverage and theoretically possesses good complementary compatibility, making it a mainstream combination system in daily chemical sunscreen formulations.

[0004] Organic sunscreens are mostly complex aromatic compounds, typically containing benzene rings, amino groups, methoxy groups, etc., which can form large conjugated light-absorbing systems. After absorbing ultraviolet energy, the molecules transition from the ground state to an excited state; some molecules can release energy through exothermic, fluorescent, or phosphorescent radiation and return to the stable ground state; however, other molecules, due to excessive energy absorption, undergo irreversible photochemical reactions such as bond breaking, isomerization, and cycloaddition, leading to the degradation and inactivation of the sunscreen.

[0005] Under natural sunlight irradiation, both AVB and OMC are prone to complex photochemical reactions. In addition to molecular isomerization and autoluminescent degradation, they can also undergo side reactions such as cycloaddition and chemical bond cleavage, generating degradation byproducts such as substituted oxyvalerate and oxybutyrate. These reactions significantly weaken the system's UV absorption capacity, causing a decrease in sun protection efficacy and directly affecting the product's effectiveness and shelf stability. Summary of the Invention

[0006] To address the shortcomings of existing OMC-AVB compound systems, such as poor photostability and easy SPF value decay, this invention provides a sunscreen composition with excellent photostability. This composition, by introducing OCT (octocrylene) and BEMT (bis-ethylhexyloxyphenol methoxyphenyl triazine) and enabling their synergistic effect, significantly reduces the photodegradation rate of OMC and AVB, solving the technical problem of ineffective single-agent photostability.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution: A sunscreen composition with synergistic photostabilizing effect, comprising, by weight parts: 4-14 parts of ethylhexyl methoxycinnamate, 1-5 parts of butyl methoxydibenzoylmethane, 0.1-8 parts of octocrylene, and 0.1-5 parts of bis-ethylhexyloxyphenol methoxyphenyl triazine.

[0008] Preferably, the sunscreen composition with synergistic photostabilizing effect comprises, by weight parts: 8-12 parts of ethylhexyl methoxycinnamate, 2-3 parts of butyl methoxydibenzoylmethane, 4-5 parts of octocrylene, and 2-3 parts of bis-ethylhexyloxyphenol methoxyphenyl triazine.

[0009] More preferably, the sunscreen composition with synergistic photostabilizing effect comprises, by weight parts: 10 parts ethylhexyl methoxycinnamate, 2.5 parts butyl methoxydibenzoylmethane, 4 parts octocrylene, and 2.5 parts bis-ethylhexyloxyphenol methoxyphenyl triazine.

[0010] Furthermore, the sunscreen composition also contains cosmetically acceptable excipients, including but not limited to solvents, emulsifiers, and thickeners. The solvent is preferably isononyl isononanoate.

[0011] The sunscreen composition with synergistic photostabilizing effect described in this invention can be used as a sunscreen active additive in different cosmetic formulations to achieve sun protection.

[0012] Furthermore, the cosmetic formulations include, but are not limited to, sunscreens, sun lotions, makeup bases, cushion BB creams, sunscreen sprays, and sunscreen serums.

[0013] The beneficial effects of the technical solution provided by the embodiments of the present invention are as follows: (1) Significant synergistic photostability effect: This application unexpectedly discovered through experiments that when OCT and BEMT are used alone, their photostability effect on OMC is limited (only able to reduce the OMC degradation rate from 47.90% in the binary system to 40.28% and 39.28%, respectively). However, when OCT and BEMT are added to the OMC-AVB system at the same time, they produce a significant synergistic effect, causing the OMC photodegradation rate in the quaternary system to drop sharply to 19.15%, which exceeds the conventional expectations of those skilled in the art.

[0014] (2) Excellent SPF retention rate: The sunscreen product using the quaternary system of the present invention has an SPF attenuation rate as low as 18.88% after irradiation, which is far better than the attenuation rate of up to 44.18% of the OMC-AVB binary system, and can maintain a longer-lasting UV protection effect.

[0015] (3) The formula is safe and readily available: The sunscreens used in this invention are all mature, safe and readily available raw materials in the cosmetics field. No special process is required, which facilitates industrial production and scale-up, and has extremely high market application prospects. Detailed Implementation

[0016] This invention discloses a sunscreen composition with excellent photostability. Those skilled in the art can refer to this document and appropriately modify the process parameters to achieve the desired result. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in this invention. The methods and applications of this invention have been described through preferred embodiments. Those skilled in the art will clearly be able to modify or appropriately change and combine the methods and applications described herein without departing from the content, spirit, and scope of this invention to implement and apply the technology of this invention.

[0017] The raw materials and reagents used in the sunscreen composition with excellent photostability provided by this invention are commercially available.

[0018] In this invention, the specified range of the mass fractions of each component (claim 1: OMC 4-14 parts, AVB 1-5 parts, OCT 0.1-8 parts, BEMT 0.1-5 parts) is determined based on the following considerations: if OMC is less than 4 parts, although photostability can be achieved, the system's UVB protection capability is insufficient; if OMC is more than 14 parts, the relative ratio of OCT and BEMT deviates from the effective quenching range, and the stabilization effect decreases. The amount of AVB is limited to 1-5 parts, aiming to form complementary UVA-UVB absorption with OMC while avoiding excessive accumulation of its photolysis products. The lower limit of OCT and BEMT (0.1 parts) is the critical effective amount to produce a detectable synergistic effect, while the upper limit (8 parts and 5 parts) takes into account both the skin feel of the formulation and cost control.

[0019] More preferably, when the OMC is 8-12 parts, AVB is 2-3 parts, OCT is 4-5 parts, and BEMT is 2-3 parts (claim 2), the mass ratio of the sum of OCT and BEMT to OMC approaches 0.5:1 to 1:1. At this point, the energy transfer efficiency is high, and the synergistic stabilizing effect is significant. In particular, when the OMC is 10 parts, AVB is 2.5 parts, OCT is 4 parts, and BEMT is 2.5 parts (claim 3), this ratio reaches an optimal balance point, and the synergistic effect is prominent.

[0020] It should be specifically noted that although the experimental section below only uses the specific point values ​​described in claim 3 for illustrative verification, the verification results are not intended to limit the scope of claims 1 and 2. Those skilled in the art, after reading the above-disclosed mechanism and experimental data, will recognize that within the numerical ranges described in claims 1 and 2, both OCT and BEMT can exist at effective concentrations sufficient to quench the excited state of OMC, and their synergistic relationship will not disappear due to conventional adjustments within this range. Therefore, those skilled in the art can expect without inventive effort that, at each endpoint and intermediate value covered by claims 1 (OMC 4-14 parts, AVB 1-5 parts, OCT 0.1-8 parts, BEMT 0.1-5 parts) and claims 2 (OMC 8-12 parts, AVB 2-3 parts, OCT 4-5 parts, BEMT 2-3 parts), a photostable effect superior to the OMC-AVB binary system can be achieved, with the synergistic effect reaching its optimal value only at the optimal point of claim 3. Any adjustments to the formulation made within the mass fraction range defined in the claims of this invention are within the scope of protection of this invention.

[0021] The preparation method of the sunscreen composition described in this invention can employ conventional heating and mixing processes in the art. Exemplarily, weighed OMC, AVB, OCT, BEMT, and cosmetically acceptable excipients (preferably isononyl isononanoate as a solvent, but not limited thereto) are placed in a reaction vessel, stirred, and heated to 60–90°C (preferably 80–85°C), maintaining a constant temperature and stirring until all materials are completely dissolved, forming a transparent and homogeneous oil phase solution; subsequently, it is allowed to cool naturally or programmed to room temperature to obtain a semi-finished sunscreen composition. If an emulsified product (such as sunscreen cream or sunscreen lotion) is required, the above-mentioned oil phase and aqueous phase (containing emulsifiers, thickeners, water, etc.) must be dissolved separately at appropriate temperatures, then mixed and emulsified under homogeneous conditions, cooled, and then packaged.

[0022] The sunscreen composition with synergistic photostabilizing effect described in this invention can be used as a sunscreen active additive in various cosmetic formulations, including but not limited to sunscreen creams, sunscreen lotions, makeup bases, cushion BB creams, sunscreen sprays, sunscreen serums, sunscreen sticks, and liquid foundations. When adding it, simply introduce the composition of this invention into the base formulation at an appropriate proportion (usually 5% to 30% of the total formulation mass, adjusted according to the target SPF value and the regulatory limits for each sunscreen agent), and routinely adjust the types and amounts of excipients according to the formulation requirements to impart broad-spectrum and long-lasting UV protection to the final product. The invention will be described in detail below through specific experimental examples, but these examples should not be construed as limiting the scope of protection of this invention.

[0023] The present invention will be further illustrated below with reference to the embodiments: Experiment 1 Test method: Accurately weigh the raw materials for each formula, add them to a clean beaker, stir and heat to 80~85 ℃, stir until completely dissolved, transparent and free of particles, cool naturally to room temperature, seal and store for later use to obtain the sample to be tested.

[0024] Use a 1mL disposable syringe to draw up the sample to be tested and spot it evenly onto a PMMA plate, controlling the coating amount to be 1.3 mg / cm2; wear a disposable finger cot to evenly coat the sample and allow it to equilibrate at room temperature for 20 min; place it in an ultraviolet aging chamber and irradiate it with a 15 W mercury lamp (main wavelength 254 nm), with an irradiation distance of 18 cm and an irradiation intensity of 0.34 mW / cm2, for 1 h of continuous irradiation, and then set it aside for use.

[0025] Following the method described in the "Cosmetic Safety Technical Specifications" (2015 edition), high-performance liquid chromatography (HPLC) was used to determine the content of sunscreen agents before and after irradiation. Sample preparation after UV irradiation: The sample on the irradiated PMMA plate was washed with methanol, diluted to 10 mL, filtered through a 0.45 μm organic filter membrane, and then injected for analysis.

[0026] Using an SPF-290S sun protection factor tester, the SPF values ​​of the samples before and after irradiation were measured, and the SPF decay rate was calculated using the following formula: SPF decay rate (%) = (SPF before irradiation - SPF after irradiation) / SPF before irradiation × 100%.

[0027] (1) Photodegradation test of single-component sunscreen Sample A: 2.5 parts of butyl methoxydibenzoylmethane (AVB) and 97.5 parts of isononyl isononanoate.

[0028] Sample B: 10 parts of ethylhexyl methoxycinnamate (OMC) and 90 parts of isononyl isononanoate.

[0029] Sample C: 2.5 parts of bis-ethylhexyloxyphenol methoxyphenyl triazine (BEMT) and 97.5 parts of isononyl isononanoate.

[0030] Sample D: 4 samples of octocrylene (OCT) and 96 samples of isononyl isononanoate.

[0031] The AD sample was subjected to ultraviolet irradiation and HPLC detection, and the SPF value was determined according to the above experimental method. The results are shown in Table 1 and Table 2.

[0032] Table 1. Changes in the content of single-component sunscreens before and after irradiation.

[0033] As shown in Table 1, the content of all single-component sunscreens decreased to varying degrees after UV irradiation. AVB showed the most severe photodegradation, with an initial content of (2.554 ± 0.118)% decreasing to only (0.273 ± 0.036)% after irradiation, a photodegradation rate as high as 89.31%. OMC's initial content was (9.773 ± 0.097)%, decreasing to (5.430 ± 0.151)% after irradiation, a photodegradation rate of 44.44%. BEMT and OCT, on the other hand, exhibited better photostability, with photodegradation rates of only 15.14% and 17.26%, respectively.

[0034] Table 2. Changes in SPF values ​​of single-component sunscreens before and after irradiation.

[0035] The SPF variation data in Table 2 are highly consistent with the content data in Table 1. AVB has the highest SPF attenuation rate (83.44%), OMC has 52.60%, and the SPF attenuation rates of BEMT and OCT are both around 20%, which verifies that BEMT and OCT have good photostability.

[0036] (2) Photodegradation test of sunscreen agents in compound system Sample E (quaternary system): 10 parts of ethylhexyl methoxycinnamate, 2.5 parts of butyl methoxydibenzoylmethane, 4 parts of octocrylene, 2.5 parts of bis-ethylhexyloxyphenol methoxyphenyl triazine, and 81 parts of isononyl isononanoate.

[0037] Sample F (ternary system): 10 parts of ethylhexyl methoxycinnamate, 2.5 parts of butyl methoxydibenzoylmethane, 4 parts of octocrylene, and 83.5 parts of isononyl isononanoate.

[0038] Sample G (ternary system): 10 parts of ethylhexyl methoxycinnamate, 2.5 parts of butyl methoxydibenzoylmethane, 2.5 parts of bis-ethylhexyloxyphenol methoxyphenyl triazine, and 85 parts of isononyl isononanoate.

[0039] Sample H (binary system): 10 parts of ethylhexyl methoxycinnamate, 2.5 parts of butyl methoxydibenzoylmethane, and 87.5 parts of isononyl isononanoate.

[0040] The samples E-H were subjected to ultraviolet irradiation and HPLC detection, and the SPF value was determined according to the above experimental methods. The results are shown in Tables 3 and 4.

[0041] Table 3. Changes in the content of each sunscreen agent in the compound system before and after irradiation.

[0042] As shown in Table 3, the degradation rate of AVB in the compound system ranged from 18.42% to 23.62%, all lower than the 89.31% of the single component, indicating that the addition of OMC, BEMT, and OCT significantly improved the photostability of AVB. However, the photodegradation of OMC varied in different compound systems. AVB promoted the degradation of OMC, with a degradation rate of 47.90% in binary system H. The addition of OCT (system F) or BEMT (system G) alone reduced the OMC degradation rate to 40.28% and 39.28%, respectively, showing a certain inhibitory effect. However, when OCT and BEMT were added together (system E), OCT and BEMT exhibited a significant synergistic stabilizing effect on OMC, with the OMC degradation rate in system E being only 19.15%.

[0043] Table 4. Changes in SPF values ​​of the compound system before and after irradiation.

[0044] The SPF attenuation results in Table 4 further confirm this trend: the SPF attenuation rate of the binary system H is as high as 44.18%, while the SPF attenuation rate of the quaternary system E drops to 18.88%, indicating that the quaternary compound system has the most durable UV protection effect and the best photostability.

[0045] This demonstrates that the OMC-AVB-OCT-BEMT quaternary compound system possesses both broad-spectrum protection and excellent photostability.

[0046] The inventors speculate that the synergistic effect is due to the fact that OCT and BEMT, in a specific ratio, can effectively quench the excited state energy generated by OMC after absorbing ultraviolet light, thereby inhibiting the breaking of its chemical bonds. Furthermore, the solubility saturation of different sunscreens in such solvent systems has a certain known tolerance range. Therefore, those skilled in the art can achieve the synergistic photostable effect of this invention by making conventional adjustments within the numerical range given in the claims.

[0047] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A sunscreen composition with synergistic photostabilizing effect, characterized in that, By weight, it contains the following components: 4-14 parts of ethylhexyl methoxycinnamate, 1-5 parts of butyl methoxydibenzoylmethane, 0.1-8 parts of octocrylene, and 0.1-5 parts of bis-ethylhexyloxyphenol methoxyphenyl triazine.

2. The sunscreen composition with synergistic photostabilizing effect according to claim 1, comprising, by weight parts: 8-12 parts of ethylhexyl methoxycinnamate, 2-3 parts of butyl methoxydibenzoylmethane, 4-5 parts of octocrylene, and 2-3 parts of bis-ethylhexyloxyphenol methoxyphenyl triazine.

3. The sunscreen composition with synergistic photostabilizing effect according to claim 2, comprising the following components by weight: 10 parts of ethylhexyl methoxycinnamate, 2.5 parts of butyl methoxydibenzoylmethane, 4 parts of octocrylene, and 2.5 parts of bis-ethylhexyloxyphenol methoxyphenyl triazine.

4. The sunscreen composition with synergistic photostabilizing effect according to claim 1, characterized in that, The sunscreen composition also contains cosmetic-acceptable excipients, including but not limited to solvents, emulsifiers, and thickeners.

5. The sunscreen composition with synergistic photostabilizing effect according to claim 4, characterized in that, The solvent is isononyl isononanoate.

6. Use of the sunscreen composition with synergistic photostabilizing effect according to any one of claims 1-5 in the preparation of cosmetics.

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