A lignin-modified titanium dioxide particle, a skin care composition, and a method of preparation

Abstract

The present application relates to the technical field of cosmetics, in particular to a kind of lignin modified titanium dioxide particles, skin care composition and preparation method, comprising the following steps: lignin is dissolved in polyol, then add titanium dioxide, heating is carried out esterification reaction.The present application studies and combines cosmetic production process, finds that with polyol as reaction solvent system, lignin can be combined with titanium dioxide stable, cover dense on the surface of titanium dioxide, and the overall stability of lignin modified titanium dioxide particles is high.This can not only significantly improve the anti-ultraviolet sunscreen performance of particles, so that it can still maintain high sunscreen effect when applied to cosmetics, and maintain the stability of cosmetic;At the same time, lignin can eliminate the oxygen free radicals generated by photochemical effect of nano titanium dioxide, so as to protect the skin, with skin care function.In addition, the chemical combination with lignin effectively avoids the toxic effect that may be caused by transdermal absorption of nano titanium dioxide, and is safer.

Description

Technical Field

[0001] This invention relates to the field of cosmetic technology, specifically to a lignin-modified titanium dioxide particle, a skin care composition, and a preparation method. Background Technology

[0002] Ultraviolet (UV) radiation is a major exogenous factor causing photoaging, pigmentation, and cancer in the skin. Based on wavelength, UV radiation can be divided into two categories: long-wave (UVA, 315-400nm) and short-wave (UVB, 280-315nm). Their penetrating power and biological effects differ significantly. UVA has chronic damaging properties: its strong penetrating power allows it to reach deep into the dermis, inducing reactive oxygen species (ROS) to damage the extracellular matrix, including collagen and elastin fibers, leading to skin laxity, deeper wrinkles, and pigmentation. It is the core cause of photoaging. Long-term cumulative UVA exposure is also associated with an increased risk of melanoma. UVB exhibits acute phototoxicity: although it has higher energy, its penetrating power is weak, mainly affecting the epidermis. It can induce acute sunburn reactions such as erythema and edema, and directly damage DNA, leading to cell mutations and becoming a major pathogenic factor for skin cancers (such as squamous cell carcinoma).

[0003] To reduce the damage caused by ultraviolet (UV) radiation to the skin, cosmetics often use physical sunscreens (such as inorganic microparticles like zinc oxide and titanium dioxide) or chemical sunscreens (such as avobenzone, octocrylene, and ethylhexyl methoxycinnamate). Physical sunscreens have a thick texture, which can easily cause whitening, oiliness, or dryness, thus affecting makeup adherence. Furthermore, high concentrations (>20%) are required to achieve the ideal SPF value. While nanoparticles can overcome these drawbacks, they pose a risk of transdermal absorption or inhalation, and their photoactivation effect may generate free radicals, leading to skin damage. Chemical sunscreens may induce contact dermatitis or phototoxic reactions, and most are lipid-soluble substances requiring surfactants for solubilization. High concentrations of surfactants can damage the skin barrier function, leading to dryness, flaking, and sensitivity reactions. In particular, damage to the lipid bilayer can exacerbate the risk of inflammation.

[0004] To overcome the limitations of physical and chemical sunscreens, researchers are dedicated to developing greener, safer, and more comprehensive sunscreens and compositions. Lignin, a major component of plant cell walls, exhibits unique advantages in the field of cosmetic sunscreens due to its complex three-dimensional network structure: lignin is formed by the cross-linking of phenylpropane units (p-coumarol, coniferyl alcohol, and sinapyl alcohol) through ether and carbon-carbon bonds, and is rich in a conjugated aromatic ring system and polyphenolic hydroxyl groups. This conjugated system can efficiently absorb ultraviolet radiation in the 280-400nm wavelength range—the benzene ring absorbs UVB (280-315nm), while the phenolic hydroxyl groups and quinone structures absorb UVA (315-400nm). Simultaneously, the abundant catechol and guaiacol structures within the molecule endow it with strong antioxidant properties. When ultraviolet radiation triggers skin lipid peroxidation, lignin can quench singlet oxygen and peroxide free radicals through the hydrogen donation mechanism of phenolic hydroxyl groups. This photostable property can synergistically enhance the durability of chemical sunscreens. Lignin nanoparticles (50-200nm) have a multi-level porous structure, which enhances the reflection of ultraviolet rays across the entire spectrum through light scattering; their abundant hydroxyl groups on the surface can form a hydrogen bond network with inorganic sunscreens such as titanium dioxide, making the sunscreen film more dense and uniform and reducing the chalky feeling.

[0005] Lignin's full-spectrum UV absorption properties, combined with inorganic sunscreens (titanium dioxide, zinc oxide, silicon dioxide, etc.), can fully utilize the sunscreen properties of both while eliminating free radicals generated by the photoactivation effect of inorganic sunscreens, achieving dual protection for the skin. This is the core idea behind the current development of lignin in sunscreen products. For example, patent document CN202210712843.9 discloses a method for preparing a lignin-based natural sunscreen complex: using water glass as a silicon source and tetrabutyl titanate as a titanium source to prepare an amino-modified composite silica / titanium dioxide sol, which is then reacted with lignin to obtain a silica / titanium dioxide / lignin composite sunscreen. Patent document CN201810666539.9 discloses a method for preparing and applying lignin-modified titanium dioxide particles: dissolving lignin in water or an organic solvent and reacting it with titanium dioxide, followed by centrifugation, washing, and drying to obtain modified particles, which are then applied to skincare products and anti-UV materials.

[0006] However, considering the needs of cosmetic production, existing processes still have shortcomings: lignin is amorphous and interacts weakly with inorganic particles, making it difficult to form a hybrid system with controllable morphology. When applied to cosmetics, its UV protection function is weakened, and the photocatalytic effect of inorganic particles has limited shielding capabilities. Therefore, lignin generally needs to be pre-modified with quaternization or reacted using sol-gel inorganic particles. However, the quaternization modification or the use of sol-gel inorganic particles requires the use of organic solvents, modifiers, and other raw materials. These substances may be toxic or non-cosmetic ingredients, and subsequent processes need to separate and remove harmful components, increasing process complexity and posing safety hazards due to residual harmful substances. This severely restricts the application of lignin as a sunscreen ingredient in skincare products. Summary of the Invention

[0007] Therefore, the primary technical problem this invention aims to solve is to provide a lignin-modified titanium dioxide particle, its preparation method, and its uses. The lignin-modified titanium dioxide particles prepared by the method exhibit stable lignin-titanium dioxide bonding, a dense coating on the titanium dioxide surface, and high overall stability. This not only significantly enhances the particles' UV protection performance, allowing them to maintain high-efficiency sun protection when applied to cosmetics and improving the stability of the cosmetics; simultaneously, lignin can eliminate oxygen free radicals generated by the photochemical effect of nano-titanium dioxide, thereby protecting the skin and providing skincare benefits. Furthermore, the chemical bonding with lignin effectively avoids the toxic effects that may be caused by transdermal absorption of nano-titanium dioxide, resulting in higher safety.

[0008] The second technical problem this invention aims to solve is to provide a skincare composition and its preparation method. In the skincare composition, the lignin-modified titanium dioxide particles are selected as an anti-ultraviolet sunscreen component and also as an emulsifier, thereby improving both the anti-ultraviolet sunscreen performance and the stability of the skincare composition.

[0009] Therefore, the present invention provides the following technical solution: In a first aspect, embodiments of the present invention provide a method for preparing lignin-modified titanium dioxide particles, comprising the following steps: Lignin was dissolved in a polyol, and then titanium dioxide was added and heated to carry out an esterification reaction.

[0010] In some embodiments, the weight parts of each reactant are as follows: 100 parts lignin; 5-50 parts of titanium dioxide; 500-2500 parts of polyols.

[0011] In some embodiments, the polyol is at least one selected from 1,2-decanediol, ethylhexylglycerol, 1,2-octanediol, 1,2-hexanediol, 1,2-pentanediol, 1,2-butanediol, 1,2-propanediol, 1,2-ethylenediol, glycerol, 1,3-propanediol, and 1,2-nonanediol. And / or, the lignin is at least one of sulfate lignin, lignin sulfonate, enzymatically hydrolyzed lignin, organic solvent lignin, or alkali lignin; And / or, the titanium dioxide is nano-titanium dioxide, which is at least one of rutile or anatase, and has a particle size range of 10nm-60nm and a content of not less than 95%.

[0012] In some embodiments, the conditions for heating to carry out the esterification reaction are 85°C-150°C, stirring for 1-8 hours, and then cooling to 80°C to obtain the reaction solution.

[0013] Secondly, embodiments of the present invention provide lignin-modified titanium dioxide particles prepared by the aforementioned method for preparing lignin-modified titanium dioxide particles.

[0014] Thirdly, embodiments of the present invention provide the use of the lignin-modified titanium dioxide particles described above in cosmetics, skin care products, and / or UV protection products.

[0015] Fourthly, embodiments of the present invention provide a skin care composition comprising lignin-modified titanium dioxide particles prepared by the method described above.

[0016] In some embodiments, the raw materials include the following parts by weight: Reaction solution: 100 parts lignin; 5-50 parts of titanium dioxide; 500-2500 parts of polyols; Aqueous phase: 1000-5000 parts water; Oil phase: 10-200 parts silicone oil; Sunscreen 50-250 parts; 1000-5000 parts of oil phase matrix.

[0017] In some embodiments, the sunscreen agent is at least one selected from the following: ethylhexyl methoxycinnamate, diethylamino hydroxybenzoyl hexyl benzoate, ethylhexyl triazine, ethylhexyl salicylate, octocrylene, avobenzone, 4-methylbenzyl camphor, bis-ethylhexyloxyphenol methoxyphenyl triazine, benzophenone-4, and butyl octyl salicylate. And / or, the oil phase matrix is ​​at least one of isohexadecane, mineral oil, beeswax, caprylic / capric triglyceride, C12-15 alcohol benzoate, isopropyl myristate, and behenol.

[0018] Fifthly, embodiments of the present invention provide a method for preparing the skincare composition, comprising the following steps: S1. Dissolve lignin in polyol, then add titanium dioxide, and heat to carry out esterification reaction to obtain reaction solution; S2. Take raw materials according to the oil phase, heat the silicone oil, sunscreen agent and oil phase matrix, stir and mix to obtain a mixture; S3. Take the raw materials according to the aqueous phase, heat the water, and then stir and mix the reaction solution obtained in step S1, the mixture obtained in step S2, and water until homogenized.

[0019] In step S1, the conditions for heating to carry out the esterification reaction are 80℃-150℃, stirring for 1-8 hours, and then cooling to 60℃-90℃.

[0020] In step S1, the silicone oil, sunscreen agent and oil phase matrix are heated to 60°C-90°C.

[0021] In step S3, the water is heated to 85℃-90℃; the reaction solution obtained in step S1, the mixture obtained in step S2, and the water are stirred and mixed for 10-30 minutes; the homogenization conditions are a temperature of 35-90℃ and a homogenization time of 10-35 minutes.

[0022] The technical solution of this invention has the following advantages: 1. This invention provides a method for preparing lignin-modified titanium dioxide particles, comprising the following steps: dissolving lignin in a polyol, then adding titanium dioxide, and heating to carry out an esterification reaction. Based on research and cosmetic manufacturing processes, this invention has found that using a polyol as the reaction solvent system allows for a faster and more thorough esterification reaction between titanium dioxide and lignin, achieving modification of nano-titanium dioxide. Lignin can stably bind with titanium dioxide, forming a dense coating on the titanium dioxide surface, and the lignin-modified titanium dioxide particles exhibit high overall stability. This not only significantly improves the particles' UV protection performance, ensuring high-efficiency sun protection when applied to cosmetics and maintaining the stability of the cosmetics; simultaneously, lignin can eliminate oxygen free radicals generated by the photochemical effect of nano-titanium dioxide, thereby protecting the skin and providing skincare benefits. Furthermore, the chemical binding with lignin effectively avoids the toxic effects that may be caused by transdermal absorption of nano-titanium dioxide, resulting in higher safety.

[0023] 2. This invention provides a skincare composition comprising lignin-modified titanium dioxide particles prepared by the aforementioned method. In this skincare composition, the lignin-modified titanium dioxide particles are selected as an anti-UV sunscreen component and also as an emulsifier, thereby improving both the anti-UV sunscreen performance and the stability of the skincare composition.

[0024] 3. This invention provides a skincare composition comprising the following raw materials in parts by weight: reaction solution: lignin, 100 parts; titanium dioxide, 5-50 parts; polyol, 500-2500 parts; aqueous phase: water, 1000-5000 parts; oil phase: silicone oil, 10-200 parts; sunscreen agent, 50-250 parts; oil phase matrix, 1000-5000 parts. Through in-depth research and analysis of the components and cosmetic preparation process of Pickering emulsion-type sunscreen compositions, and through continuous experimentation and investigation, this invention has finally determined that the composition of this invention consists of aqueous phase components: lignin, nano titanium dioxide, polyol, and water, and oil phase components: silicone oil, sunscreen agent, and oil phase matrix. First, lignin is dispersed and dissolved using polyol as a solvent. Then, nanoparticles formed by the hydrothermal esterification reaction of lignin and titanium dioxide are used as emulsifiers in the Pickering emulsion skincare composition. These nanoparticles are then combined with selected oil phase components and stirred and homogenized. The above-mentioned nano solid particles can be adsorbed at the oil-water interface of the emulsion to form a stable water-in-oil or oil-in-water emulsion. The resulting skincare composition not only has high UV protection performance but also high stability.

[0025] Furthermore, this invention creatively combines the preparation process of the emulsifier required for Pickering emulsion preparation—the aforementioned nano-solid particles—with the preparation process of the sunscreen skincare composition, avoiding the use of organic solvents or harmful substances in the preparation process of nano-titanium dioxide modification, simplifying the preparation process and flow of Pickering emulsion-type sunscreen composition, and realizing a green, environmentally friendly, and safe composition preparation process.

[0026] Furthermore, the emulsion composition of the present invention selects the aforementioned nano-solid particles as emulsifiers, which overcomes the defect that the oil phase and water phase components in the system must use surfactants to reduce the surface tension of the two phases in order to maintain the stability of the skin care composition. The use of surfactants can be omitted, which can reduce the irritation of surfactants to the skin and the greasy feeling brought about by the application process. Detailed Implementation

[0027] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0028] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0029] In the following examples, the nano-titanium dioxide is at least one of rutile or anatase, and the content of the particle size range of 10nm-60nm is not less than 95%.

[0030] Enzymatically hydrolyzed lignin, sodium lignin sulfonate, alkali lignin, and sulfate lignin were all purchased from Shandong Longli Biotechnology Co., Ltd. Silicone oil was purchased from Guangzhou Tinci Advanced Materials Co., Ltd.

[0031] Example 1 This embodiment provides a method for preparing lignin-modified titanium dioxide particles, including the following steps: Take 100g of enzymatically hydrolyzed lignin and dissolve it in 800g of 1,2-propanediol. Then add 15g of rutile nano-titanium dioxide (30nm content not less than 95%). Then heat to 110℃ and stir for 3 hours. Cool down to 80℃ to obtain reaction solution ①, which is ready for use.

[0032] Example 2 This embodiment provides a method for preparing lignin-modified titanium dioxide particles, including the following steps: Dissolve 100g of sodium lignosulfonate in 2000g of glycerol, then add 5g of anatase nano titanium dioxide (60nm content not less than 95%), then heat to 85℃, stir for 8 hours, cool to 80℃ to obtain reaction solution ②, which is ready for use.

[0033] Example 3 This embodiment provides a method for preparing lignin-modified titanium dioxide particles, including the following steps: Dissolve 100g of alkali lignin in 1500g of octyl glycol, then add 10g of rutile nano titanium dioxide (30nm content not less than 95%), then heat to 130℃, stir for 1.5 hours, cool to 80℃ to obtain reaction solution ③, which is ready for use.

[0034] Example 4 This embodiment provides a method for preparing lignin-modified titanium dioxide particles, including the following steps: Dissolve 100g of sulfate lignin in 2500g of 1,2-decanediol, then add 25g of anatase nano titanium dioxide (10nm content not less than 95%), then heat to 150℃, stir for 1 hour, cool to 80℃ to obtain reaction solution ④, which is ready for use.

[0035] Example 5 This embodiment provides a method for preparing lignin-modified titanium dioxide particles, including the following steps: Dissolve 100g of alkali lignin in 500g of 1,2-pentanediol, then add 35g of rutile nano titanium dioxide (40nm content not less than 95%), then heat to 100℃, stir for 4 hours, cool to 80℃ to obtain reaction solution ⑤, which is ready for use.

[0036] Example 6 This embodiment provides a skin care composition prepared from the following raw materials: Reaction solution: The reaction solution in Example 1; Aqueous phase: 3000g of water; Oil phase: 20g of silicone oil; Octocrylene 120g; 2000g of isohexadecane.

[0037] The preparation method includes the following steps: (1) Oil phase: 20g silicone oil, 120g octocrylene and 2000g isohexadecane were mixed and heated to 80°C to obtain a mixture; (2) Heat 3000g of water to 85°C, add the reaction solution ① in step 1 and the mixture in step (1) to the water respectively, stir and mix for 25 minutes, homogenize for 10 minutes, cool down to 40°C, add fragrance and preservative, continue to homogenize for 10 minutes, and obtain skin care composition.

[0038] Example 7 This embodiment provides a skincare composition comprising the following ingredients: Reaction solution: The reaction solution in Example 2; Aqueous phase: 3000g of water; Oil phase: 20g of silicone oil; Octocrylene 120g; 2000g of isohexadecane.

[0039] The preparation method includes the following steps: (1) Oil phase: 30g silicone oil, 120g octocrylene and 2000g isohexadecane were mixed and heated to 80°C to obtain a mixture; (2) Heat 3000g of water to 85°C, add the reaction solution ② in step 2 and the mixture in step (1) to the water respectively, stir and mix for 25 minutes, homogenize for 10 minutes, cool down to 40°C, add fragrance and preservative, continue to homogenize for 10 minutes, and obtain the skin care composition of the present invention.

[0040] Example 8 This embodiment provides a skincare composition comprising the following ingredients: Reaction solution: The reaction solution in Example 3; Aqueous phase: 3000g of water; Oil phase: 20g of silicone oil; Octocrylene 120g; 2000g of isohexadecane.

[0041] The preparation method includes the following steps: (1) Oil phase: 20g silicone oil, 120g octocrylene and 2000g isohexadecane were mixed and heated to 80°C to obtain a mixture; (2) Heat 3000g of water to 85°C, add the reaction solution ③ of Example 3 and the mixture of step (1) to the water respectively, stir and mix for 25 minutes, homogenize for 10 minutes, cool down to 40°C, add fragrance and preservative, continue to homogenize for 10 minutes, and obtain the skin care composition of the present invention.

[0042] Example 9 This embodiment provides a skincare composition comprising the following ingredients: Reaction solution: The reaction solution in Example 4; Aqueous phase: 3000g of water; Oil phase: 20g of silicone oil; Octocrylene 120g; 2000g of isohexadecane.

[0043] The preparation method includes the following steps: (1) Oil phase: 20g silicone oil, 120g octocrylene and 2000g isohexadecane were mixed and heated to 80°C to obtain a mixture; (2) Heat 3000g of water to 5°C, add the reaction solution ④ in Example 4 and the mixture in step (1) to the heated water, stir and mix for 25 minutes, homogenize for 10 minutes, cool down to 40°C, add fragrance and preservative, continue to homogenize and stir for 10 minutes to obtain the skin care composition of the present invention.

[0044] Example 10 This embodiment provides a skincare composition comprising the following ingredients: Reaction solution: The reaction solution in Example 5; Aqueous phase: 3000g of water; Oil phase: 20g of silicone oil; Octocrylene 120g; 2000g of isohexadecane.

[0045] The preparation method includes the following steps: (1) Oil phase: 20g silicone oil, 120g octocrylene and 2000g isohexadecane were mixed and heated to 80°C to obtain a mixture; (2) Heat 3000g of water to 85°C, add the reaction solution ⑤ of Example 5 and the mixture of step (1) to the water respectively, stir and mix for 25 minutes, homogenize for 10 minutes, cool down to 40°C, add fragrance and preservative, continue to homogenize and stir for 10 minutes to obtain the skin care composition of the present invention.

[0046] Comparative Example 1 The difference between this comparative example and Example 6 is that each of the raw materials in Example 1 is added at once in step (2) of Example 6 to replace the original reaction solution ①, and the rest is the same as in Example 6.

[0047] Comparative Example 2 The difference between this comparative example and Example 7 is that each of the raw materials in Example 2 is added at once in step (2) of Example 7 to replace the original reaction solution ②, and the rest is the same as in Example 7.

[0048] Comparative Example 3 The difference between this comparative example and Example 8 is that each of the raw materials in Example 3 is added at once in step (2) of Example 8 to replace the original reaction solution ③, and the rest is the same as in Example 8.

[0049] Comparative Example 4 The difference between this comparative example and Example 9 is that each of the raw materials in Example 4 is added at once in step (2) of Example 9 to replace the original reaction solution ④, and the rest is the same as in Example 9.

[0050] Comparative Example 5 The difference between this comparative example and Example 10 is that each of the raw materials in Example 5 is added at once in step (2) of Example 10 to replace the original reaction solution ⑤, and the rest is the same as in Example 10.

[0051] Comparative Example 6 The difference between this comparative example and Example 6 is that the mass of 1,2-propanediol in the reaction solution ① preparation step of Example 1 is replaced with water, while the rest is the same as in Example 6.

[0052] Comparative Example 7 The difference between this comparative example and Example 7 is that the glycerol in the reaction solution ② preparation step of Example 2 is replaced with water by mass, while the rest is the same as in Example 7.

[0053] Comparative Example 8 The difference between this comparative example and Example 8 is that the octyl glycol in the preparation step ③ of the reaction solution in Example 3 is replaced with water by mass, while the rest is the same as in Example 8.

[0054] Comparative Example 9 The difference between this comparative example and Example 9 is that the mass of 1,2-decanediol in the preparation step ④ of the reaction solution in Example 4 is replaced with water, while the rest is the same as in Example 9.

[0055] Comparative Example 10 The difference between this comparative example and Example 10 is that the mass of 1,2-pentanediol in the reaction solution preparation step ⑤ of Example 5 is replaced with water, while the rest is the same as in Example 10.

[0056] Experiment Example 1: Stability Test Test samples: Skin care compositions prepared in Examples 6-10 and Comparative Examples 1-10.

[0057] Test method: Place the sample at 45℃ and observe for 90 days, and observe the condition of the sample with the naked eye.

[0058] The test results are shown in the table below: Table 1 Stability Test Results

[0059] Conclusion: From the stability test results of Experimental Example 1, it can be seen that in Examples 6-10, lignin and nano-titanium dioxide react in a non-aqueous system to generate stable nano-solid particles as emulsifiers, which reduces the surface tension of the oil-water interface of the composition, thereby forming a stable water / oil (or oil / water) system. In Comparative Examples 1-5, since the components in Examples 1-5 were not prepared by the method of preparing lignin-modified titanium dioxide particles described in this invention, i.e., reaction solutions ①-⑤, but were added all at once in step (2), under the preparation conditions, lignin and nano-titanium dioxide in the system failed to form stable nano-solid particles. Therefore, the water / oil (or oil / water) system formed in the composition was not stable enough, and oil-water separation occurred during the stability test. In Comparative Examples 6-10, the polyol in the reaction solution was replaced with water. Due to the presence of water in the reaction system, lignin failed to form stable nano-solid particles with nano-titanium dioxide. The emulsion system formed by the composition was weak, and oil-water separation occurred during the stability test. This demonstrates that the lignin-modified titanium dioxide nanoparticles prepared according to the method of the present invention can effectively stabilize the composition and significantly improve the stability of the system when used as an emulsifier in Pickering emulsion compositions.

[0060] Experiment Example 2: Sunscreen Performance Evaluation Test samples: Examples 6-10 and Comparative Examples 1-10.

[0061] Test method: The sun protection factor (SPF) value of the test samples was determined using a sun protection factor measurement system (SPF-290S) according to the instrument testing procedures.

[0062] The test results are shown in Table 2 below: Table 2 Results of Sun Protection Factor (SPF) Measurement for Samples

[0063] As shown in the table above, the sun protection index of the skincare compositions prepared in Examples 6-10 is significantly better than that of Comparative Examples 1-10. This indicates that in a non-aqueous system using polyol as a solvent, the lignin-modified titanium dioxide nanoparticles obtained by the esterification reaction between lignin and nano-titanium dioxide not only maintain the stability of the composition but also significantly improve its sun protection performance. The main reasons are: 1) The intermolecular forces of the lignin-modified nano-titanium dioxide are weakened, allowing for full and uniform dispersion in the composition, thus improving the UV absorption efficiency of both nano-titanium dioxide and lignin; 2) The lignin-modified titanium dioxide nanoparticles... As an emulsifier in the Pickering emulsion composition, the nanoparticles formed are uniformly distributed at the oil-water interface of the emulsion, forming an oil / water (or water / oil) emulsion with smaller particle size, thereby improving the overall sun protection efficacy of the skin care composition. In contrast, in the comparative example, lignin and titanium dioxide failed to combine to form stable lignin-modified titanium dioxide nanoparticles. Agglomeration occurred between the solids, and they could not play the role of emulsifier in stabilizing the composition. Therefore, it was difficult to form a stable oil / water (or water / oil) emulsion, affecting the stability of the skin care composition and thus affecting its sun protection performance.

[0064] Experiment Example 3: Safety Assessment Test samples: Examples 6-10 and Comparative Examples 1-10.

[0065] Test Method: According to the requirements of "6.1 Occlusive Patch Test" in Chapter 7, "Human Safety Testing Methods," of the "Cosmetic Safety Technical Specifications" (2015 edition), 30 volunteers aged 18-50 years were selected as test subjects. Two subjects were assigned to each sample. A patch applicator containing 0.020g of the sample was applied to the flexor side of the subject's forearm using hypoallergenic adhesive tape. The applicator was gently pressed with the palm to ensure even application to the skin for 24 hours. Skin reactions were observed 30 minutes (after the pressure mark disappeared), 24 hours, and 48 hours after removing the patch applicator, and the results were recorded. Test results are shown in Table 3. Table 3. Skin reaction results of closed patch test on sample skin

[0066] Note: 1) The numbers in the table represent the number of cases with different skin reactions.

[0067] 2) Grading and description of skin reaction severity: - indicates a negative reaction; ± indicates a suspicious reaction with only slight erythema; + indicates a weak positive reaction (erythema reaction), with erythema, infiltration, edema, and possible papules; + indicates a strong positive reaction (herpes reaction), with erythema, infiltration, edema, papules, and vesicles; the reaction may extend beyond the tested area; + indicates an extremely strong positive reaction (confluent herpes reaction), with obvious erythema, severe infiltration, edema, and confluent vesicles; the reaction extends beyond the tested area.

[0068] Table 3 (continued): Skin reaction results of closed patch test on sample skin

[0069] Skin patch tests showed that the irritation levels of the subjects' skin were basically the same as those of the comparative examples. Except for a few subjects who may have a "weak erythema" reaction due to their own skin conditions, the vast majority of subjects showed a negative reaction with no skin irritation. This indicates that: 1) the components selected in this invention are all raw materials that are safe for human skin, and their reasonable combination will not cause damage to human skin; 2) the composition obtained by the preparation process of this invention does not change the safety of the composition and its components.

[0070] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing lignin-modified titanium dioxide particles, characterized in that, Includes the following steps: Lignin was dissolved in a polyol, and then titanium dioxide was added and heated to carry out an esterification reaction.

2. The method for preparing lignin-modified titanium dioxide particles according to claim 1, characterized in that, The weight parts of each reactant are as follows: 100 parts lignin; 5-50 parts of titanium dioxide; 500-2500 parts of polyols.

3. The method for preparing lignin-modified titanium dioxide particles according to claim 1 or 2, characterized in that, The polyol is at least one selected from 1,2-decanediol, ethylhexylglycerol, 1,2-octanediol, 1,2-hexanediol, 1,2-pentanediol, 1,2-butanediol, 1,2-propanediol, 1,2-ethylenediol, glycerol, 1,3-propanediol, and 1,2-nonanediol. And / or, the lignin is at least one of sulfate lignin, lignin sulfonate, enzymatically hydrolyzed lignin, organic solvent lignin, or alkali lignin; And / or, the titanium dioxide is nano-titanium dioxide, which is at least one of rutile or anatase, and has a particle size range of 10nm-60nm and a content of not less than 95%.

4. The method for preparing lignin-modified titanium dioxide particles according to claim 1 or 2, characterized in that, The conditions for the esterification reaction by heating are 85℃-150℃, stirring for 1 hour-8 hours, and then cooling to 80℃ to obtain the reaction solution.

5. A lignin-modified titanium dioxide particle prepared by the method for preparing lignin-modified titanium dioxide particles according to any one of claims 1-4.

6. The use of the lignin-modified titanium dioxide particles as described in claim 5 in cosmetics, skin care products and / or UV protection products.

7. A skincare composition, characterized in that, The lignin-modified titanium dioxide particles prepared by the method described in any one of claims 1-4 are included.

8. The skincare composition according to claim 7, characterized in that, The ingredients include the following parts by weight: Reaction solution: 100 parts lignin; 5-50 parts of titanium dioxide; 500-2500 parts of polyols; Aqueous phase: 1000-5000 parts water; Oil phase: 10-200 parts silicone oil; Sunscreen 50-250 parts; 1000-5000 parts of oil phase matrix.

9. The skincare composition according to claim 8, characterized in that, The sunscreen agent is at least one of the following: ethylhexyl methoxycinnamate, diethylamino hydroxybenzoyl hexyl benzoate, ethylhexyl triazine, ethylhexyl salicylate, octocrylene, avobenzone, 4-methylbenzyl camphor, bis-ethylhexyloxyphenol methoxyphenyl triazine, benzophenone-4, and butyl octyl salicylate. And / or, the oil phase matrix is ​​at least one of isohexadecane, mineral oil, beeswax, caprylic / capric triglyceride, C12-15 alcohol benzoate, isopropyl myristate, and behenol.

10. A method for preparing a skincare composition according to any one of claims 7-9, characterized in that, Includes the following steps: S1. Dissolve lignin in polyol, then add titanium dioxide, heat to carry out esterification reaction, cool down to obtain reaction solution; S2. Take raw materials according to the oil phase, heat the silicone oil, sunscreen agent and oil phase matrix, stir and mix to obtain a mixture; S3. Take the raw materials according to the aqueous phase, heat the water, and then stir and mix the reaction solution obtained in step S1, the mixture obtained in step S2, and water until homogenized.

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