CN117462425B

CN117462425B - Preparation method and application of sun-screening agent for improving sun-screening capability by densely rearranging sun-screening film through water induction

Info

Publication number: CN117462425B
Application number: CN202311488416.8A
Authority: CN
Inventors: 张少峰; 王军; 张启清; 谭琪; 曾飒
Original assignee: Guangzhou Xiaotan Technology Co ltd; Guangzhou Ridgepole Biological Technology Co ltd
Current assignee: Guangzhou Xiaotan Technology Co ltd; Guangzhou Ridgepole Biological Technology Co ltd
Priority date: 2023-11-09
Filing date: 2023-11-09
Publication date: 2024-08-27
Anticipated expiration: 2043-11-09
Also published as: CN117462425A

Abstract

The invention provides a preparation method and application of a sunscreen agent for improving sun-screening ability by densely rearranging a water-induced sun-screening film. According to the invention, the modification of the surfaces of the zinc oxide and the titanium dioxide with specific particle sizes is finished by using the modifier with specific components, so that the obtained sun-screening agent can be self-assembled on the surface of the skin to form a uniform and compact sun-screening film, uniform coating can be realized without applying special and complicated coating skills, rearrangement can be realized after water is met, and the sun-screening capability is further improved.

Description

Preparation method and application of sun-screening agent for improving sun-screening capability by densely rearranging sun-screening film through water induction

Technical Field

The invention belongs to the technical field of cosmetics. More particularly, to a method for preparing a sunscreen agent by densely rearranging a water-induced sun-screening film to improve sun-screening capability and application thereof.

Background

Zinc oxide and titanium dioxide can prevent ultraviolet rays from reaching the skin by physical means such as reflection, scattering and the like, and further protect the skin from UVB and UVA, so that zinc oxide and titanium dioxide are often added into sun-screening products as sun-screening active ingredients. However, zinc oxide and titanium dioxide are solid inorganic powder, so that the zinc oxide and titanium dioxide are difficult to uniformly spread on the surface of skin, a sun-proof layer with different thickness is easy to form, the thinner position of the sun-proof layer can be penetrated by ultraviolet rays more easily than the thicker position of the sun-proof layer, the situation of local excessive exposure is easier to occur, the local skin becomes red or black, and further the skin problems such as uneven skin color, sunburn and the like occur. In addition, the sun-screening product containing zinc oxide and titanium dioxide is usually easy to rub mud when in use, namely, the zinc oxide and the titanium dioxide are not uniformly coated on the surface of skin, small macroscopic sun-screening agent particles are formed, and the sun-screening agent particles are easy to fall off from the skin, so that the sun-screening capability of the sun-screening product is reduced, and bad skin feel and experience are given to consumers. In order to solve the above problems, consumers generally need to learn and apply professional and complicated techniques to apply the paint, but it is still impossible to ensure that the paint is completely uniform and no paste is rubbed, and the product with complicated application method is difficult to adhere to.

Therefore, developing a sunscreen product which has high sun protection value, is not easy to rub mud, can be easily and uniformly smeared without applying complicated smearing skills, and is very important for reducing skin problems such as uneven complexion, sunburn and the like.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide a preparation method of a sun-screening agent, and the sun-screening agent is prepared by selecting zinc oxide and titanium dioxide with specific particle sizes and modifying the zinc oxide and the titanium dioxide by a specific method, so that the obtained sun-screening agent can form a uniform and compact sun-screening film on the surface of skin by self-assembly, can realize uniform coating without learning special and complicated coating skills, is not easy to rub mud, and realizes a better sun-screening effect.

The primary object of the invention is to provide a preparation method of the sun-screening agent.

It is a further object of the present invention to provide sunscreens made by the process.

It is a further object of the present invention to provide the use of said sunscreens in the preparation of sunscreening products.

It is a further object of the present invention to provide a sunscreen product containing said sunscreen agent.

The above object of the present invention is achieved by the following technical scheme:

the invention provides a preparation method of a sun-screening agent, which specifically comprises the following steps:

S1, adding titanium dioxide with the particle size of 10-100 nm into a modifier A for modification, and drying to obtain modified titanium dioxide; the modifier A is an organic solvent containing C2-11 silane, and the C2-11 silane is C2-11 triethoxysilane or C2-11 trichlorosilane;

S2, adding zinc oxide with the particle size of 20-200 nm into the modifier B for modification, and drying to obtain modified zinc oxide; the modifier B is an organic solvent containing C2-11 silane and C12-20 linear fatty acid or an organic solvent containing C2-11 silane and polydimethylsiloxane; the C2-11 silane is C2-11 triethoxysilane or C2-11 trichlorosilane; the mass ratio of the C2-11 silane to the C12-20 linear fatty acid is 1:1 to 5; the mass ratio of the C2-11 silane to the polydimethylsiloxane is 1:1 to 5;

s3, uniformly mixing the modified titanium dioxide, the modified zinc oxide and the dispersing agent to obtain the sun-screening agent.

The invention researches the properties of titanium dioxide and zinc oxide, and discovers that the particle size of the titanium dioxide and zinc oxide has obvious influence on the smearing effect and the sun-screening performance of the sun-screening agent for the first time, and the particle size of the titanium dioxide and the particle size of the zinc oxide are specifically controlled and modified by combining with a modifier with specific components to finish the directional modification of the surfaces of the zinc oxide and the titanium dioxide, so that the titanium dioxide and the titanium dioxide can self-assemble on the surfaces of the skin to form a uniform and compact sun-screening film, can easily realize uniform smearing without learning specialized and complicated smearing skills, and can also rearrange after meeting water, thereby further improving the sun-screening capability.

Further, the mass ratio of the titanium dioxide to the modifier A in the S1 is 1:1 to 10.

Further, the mass ratio of the C2-11 silane to the organic solvent in S1 is 1:1 to 10.

Further, the C2-11 triethoxysilane in S1 is one or more of triethoxyethyl silane, butyl triethoxysilane, hexyl triethoxysilane, triethoxyoctyl silane and n-decyl triethoxysilane.

Further, the C2-11 trichlorosilane in the S1 is one or more of ethyl trichlorosilane, butyl trichlorosilane, hexyl trichlorosilane, octyl trichlorosilane and decyl trichlorosilane.

Further, the organic solvent of S1 is C4-8 alkane, such as n-octane, n-heptane, n-hexane, n-pentane or n-butane, etc.

Further, the modification in S1 is realized by homogeneously stirring for 2-12 h under the condition of 200-2500 rpm.

Further, the mass ratio of the zinc oxide to the modifier B in S2 is 1:1 to 25.

Further, the ratio of the total mass of the C2-11 silane and the C12-20 linear fatty acid to the mass of the organic solvent in S2 is 1:1 to 10.

Further, the ratio of the total mass of the C2-11 silane and the polydimethylsiloxane to the mass of the organic solvent in S2 is 1:1 to 10.

Further, the C2-11 triethoxysilane in S2 is one or more of triethoxyethyl silane, butyl triethoxysilane, hexyl triethoxysilane, triethoxyoctyl silane and n-decyl triethoxysilane.

Further, the C2-11 trichlorosilane in the S2 is one or more of ethyl trichlorosilane, butyl trichlorosilane, hexyl trichlorosilane, octyl trichlorosilane and decyl trichlorosilane.

Further, the C12-20 straight-chain fatty acid in S2 is one or more of lauric acid, myristic acid, palmitic acid, stearic acid and eicosanoic acid.

Further, the organic solvent of S2 is C4-8 alkane, such as n-octane, n-heptane, n-hexane, n-pentane or n-butane, etc.

Further, the modification in S2 is realized by homogeneously stirring for 1-20 h under the condition of 200-2500 rpm.

Further, the dispersant of S3 is C4-8 alkane, such as n-octane, n-heptane, n-hexane, n-pentane or n-butane, etc.

Further, the mass ratio of the modified titanium dioxide to the modified zinc oxide in the S3 is 1-5: 1.

Further, the dispersant of S3 may be used in an amount sufficient to submerge the modified titanium dioxide and the modified zinc oxide.

Further, the mixing in the step S3 is realized by homogenizing and stirring for 12-48 hours under the condition of 200-2500 rpm.

Further, the evenly mixed materials are centrifuged after S3, for example, centrifugation is carried out for 5-25 min under the condition of 10000-20000 rpm.

Further, the centrifugal process is followed by drying.

The sun-screening agent prepared by the method can form a uniform and compact sun-screening film on the surface of the skin by self-assembly, can easily realize uniform coating without learning specialized and complicated coating skills, and can also rearrange after meeting water so as to further improve sun-screening capability. Therefore, the sun-screening agent prepared by the method, the application of the sun-screening agent in preparing sun-screening products and the sun-screening products containing the sun-screening agent are all within the protection scope of the invention.

The invention has the following beneficial effects:

According to the invention, the modification of the surfaces of the zinc oxide and the titanium dioxide with specific particle sizes is finished by using the modifier with specific components, so that the obtained sun-screening agent can be self-assembled on the surface of the skin to form a uniform and compact sun-screening film, can be easily and uniformly coated without applying special and complicated coating skills, can be rearranged after meeting water, and further improves sun-screening capability.

Detailed Description

The present invention is further illustrated below with reference to specific examples, which are not intended to limit the invention in any way. Unless specifically stated otherwise, the reagents, methods and apparatus employed in the present invention are those conventional in the art.

Reagents and materials used in the following examples are commercially available unless otherwise specified.

Example 1 preparation of sunscreens

S1, adding triethoxy octyl silane into n-hexane (controlling the mass ratio of the triethoxy octyl silane to the n-hexane to be 1:4) to obtain a modifier A; adding titanium dioxide with the particle size of 30-70 nm into the modifier A (controlling the mass ratio of the titanium dioxide to the modifier A to be 1:5), homogenizing and stirring for 6 hours under the condition of 1500rpm, and drying by spray drying to obtain modified titanium dioxide;

S2, mixing triethoxyoctyl silane and stearic acid according to the weight ratio of 1:3, adding the mixture into n-hexane (controlling the ratio of the total mass of stearic acid and triethoxyoctylsilane to the mass of n-hexane to be 1:4) to obtain a modifier B; adding zinc oxide with the particle size of 50-100 nm into the modifier B (controlling the mass ratio of the zinc oxide to the modifier B to be 1:20), homogenizing and stirring for 15 hours under the condition of 1500rpm, and drying by spray drying to obtain modified zinc oxide;

S3, mixing the modified titanium dioxide and the modified zinc oxide according to the ratio of 2.5:1 (controlling the dosage of the n-hexane to be enough to submerge the modified titanium dioxide and the modified zinc oxide), homogenizing and stirring for 20 hours under the condition of 1500rpm (the n-hexane is required to be continuously supplemented in the homogenizing and stirring process to keep the liquid level of the system unchanged), centrifuging for 15 minutes under the condition of 16000rpm, and then placing the precipitate obtained by centrifugation in a 60 ℃ oven for drying to obtain the sun-screening agent.

Example 2 preparation of sunscreens

S1, adding triethoxy octyl silane into n-hexane (controlling the mass ratio of the triethoxy octyl silane to the n-hexane to be 1:1) to obtain a modifier A; adding titanium dioxide with the particle size of 10-30 nm into the modifier A (controlling the mass ratio of the titanium dioxide to the modifier A to be 1:1), homogenizing and stirring for 12 hours under the condition of 200rpm, and drying by spray drying to obtain modified titanium dioxide;

S2, mixing triethoxyoctyl silane and stearic acid according to the weight ratio of 1:1, and then adding the mixture into n-hexane (controlling the ratio of the total mass of stearic acid and triethoxyoctylsilane to the mass of n-hexane to be 1:10) to obtain a modifier B; adding zinc oxide with the particle size of 100-200 nm into the modifier B (controlling the mass ratio of the zinc oxide to the modifier B to be 1:25), homogenizing and stirring for 20 hours under the condition of 200rpm, and drying by spray drying to obtain modified zinc oxide;

s3, mixing modified titanium dioxide and modified zinc oxide according to a proportion of 5:1 (controlling the dosage of the n-hexane to be enough to submerge the modified titanium dioxide and the modified zinc oxide), homogenizing and stirring for 48 hours under the condition of 200rpm (the n-hexane is required to be continuously supplemented in the homogenizing and stirring process to keep the liquid level of the system unchanged), centrifuging for 25 minutes under the condition of 10000rpm, and then placing the precipitate obtained by centrifugation in a 50 ℃ oven for drying to obtain the sun-screening agent.

Example 3 preparation of sunscreens

S1, adding triethoxy octyl silane into n-hexane (controlling the mass ratio of the triethoxy octyl silane to the n-hexane to be 1:10) to obtain a modifier A; adding titanium dioxide with the particle size of 70-100 nm into the modifier A (controlling the mass ratio of the titanium dioxide to the modifier A to be 1:10), homogenizing and stirring for 2 hours under the condition of 2500rpm, and drying by spray drying to obtain modified titanium dioxide;

S2, mixing triethoxyoctyl silane and stearic acid according to the weight ratio of 1:5, uniformly mixing, and adding into n-hexane (controlling the ratio of the total mass of stearic acid and triethoxyoctylsilane to the mass of n-hexane to be 1:1) to obtain a modifier B; adding zinc oxide with the particle size of 20-50 nm into the modifier B (controlling the mass ratio of the zinc oxide to the modifier B to be 1:1), homogenizing and stirring for 1h under the condition of 2500rpm, and drying by spray drying to obtain modified zinc oxide;

S3, mixing the modified titanium dioxide and the modified zinc oxide according to the proportion of 1:1 (controlling the dosage of the n-hexane to be enough to submerge the modified titanium dioxide and the modified zinc oxide), homogenizing and stirring for 12 hours under the condition of 2500rpm (the n-hexane is required to be continuously supplemented in the homogenizing and stirring process to keep the liquid level of the system unchanged), centrifuging for 5 minutes under the condition of 20000rpm, and then placing the precipitate obtained by centrifugation in an oven at 80 ℃ for drying to obtain the sun-screening agent.

Example 4 preparation of sunscreens

The difference from example 1 is that both S1 and S2 triethoxyoctylsilane are replaced with triethoxyethylsilane and S2 stearic acid is replaced with lauric acid.

Example 5 preparation of sunscreens

The difference from example 1 is that both S1 and S2 triethoxyoctylsilane are replaced with butyltrichlorosilane and S2 stearic acid is replaced with myristic acid.

Example 6 preparation of sunscreens

The difference from example 1 is that both S1 and S2 triethoxyoctylsilane are replaced with hexyltrichlorosilane and S2 stearic acid is replaced with palmitic acid.

Example 7 preparation of sunscreens

The difference from example 1 is that both S1 and S2 triethoxyoctylsilane are replaced with decyltrichlorosilane and S2 stearic acid is replaced with eicosanoic acid.

Example 8 preparation of sunscreens

The difference is that S2 stearic acid is replaced by polydimethylsiloxane as in example 1.

Comparative example 1

The difference is that the particle diameter of the titanium dioxide is 1 to 10nm as in example 1.

Comparative example 2

The difference is that the particle diameter of the titanium dioxide is 100 to 200nm as in example 1.

Comparative example 3

The difference is that the particle size of zinc oxide is 1 to 20nm as in example 1.

Comparative example 4

The difference is that the particle size of zinc oxide is 200 to 300nm as in example 1.

Comparative example 5

The difference from example 1 is that S1 is not performed and S3 modified titanium dioxide is replaced with equal mass of modified zinc oxide.

Comparative example 6

The difference from example 1 is that S2 is not performed and S3 modified zinc oxide is replaced with modified titanium dioxide of equal mass.

Comparative example 7

The difference is that, as in example 1, both S1 and S2 triethoxyoctylsilane are replaced with equal mass of stearic acid.

Comparative example 8

The difference is that the S2 stearic acid is replaced by triethoxyoctylsilane of equal mass as in example 1.

Comparative example 9

The difference is that 2/3 of the mass of triethoxyoctylsilane in S1 is replaced with stearic acid as in example 1.

Comparative example 10

The difference from example 1 is that both S1 and S2 triethoxyoctylsilane are replaced by trimethylchlorosilane of equal mass.

Comparative example 11

The difference from example 1 is that both S1 and S2 triethoxyoctylsilane are replaced by equal mass of dodecyl trichlorosilane.

Comparative example 12

The difference from example 1 is that both S1 and S2 triethoxyoctylsilane are replaced with equal mass fluorosilanes.

Comparative example 13

The difference is that the S2 stearic acid is replaced by an equal mass of decanoic acid as in example 1.

Comparative example 14

The difference is that the S2 stearic acid is replaced by equal mass of behenic acid as in example 1.

Comparative example 15

The difference from example 1 is that the homogeneous stirring of S3 is carried out under UV light irradiation under the following conditions: the wavelength of the ultraviolet lamp is 254nm, the power is 12W, and the distance between the solution system and the ultraviolet lamp is 10cm.

Comparative example 16

The difference from example 1 is that S1 and S2 are not performed, i.e., this comparative example is specifically as follows:

Mixing titanium dioxide with the particle size of 30-70 nm and zinc oxide with the particle size of 50-100 nm according to the proportion of 2.5:1 (the dosage of the n-hexane is controlled to be enough to immerse titanium dioxide and zinc oxide), homogenizing and stirring for 20 hours at 1500rpm (the n-hexane is required to be continuously supplemented in the homogenizing and stirring process to keep the liquid level of the system unchanged), centrifuging for 15 minutes at 16000rpm, and then placing the precipitate obtained by centrifugation in a 60 ℃ oven for drying to obtain the sun-screening agent.

Experimental example 1 preparation of sunscreen products 1 to 24

S1, 20wt% of the sun-screening agents obtained in examples 1 to 8 and comparative examples 1 to 16, 8wt% of an ultraviolet absorbent MC80, 2wt% of an ultraviolet absorbent Tinosorb S, 2wt% of an ultraviolet absorbent Uvinul A plus, 2wt% of PEG-9 polydimethylsiloxane ethyl polydimethylsiloxane, 3wt% of octocrylene, 3wt% of ethylhexyl salicylate, 0.5wt% of bentonite, 1wt% of phenylbenzimidazole sulfonic acid and 20wt% of polydimethylsiloxane are uniformly mixed, and 100wt% of water is used for supplementing.

S2, homogenizing the product obtained in the S1 in a homogenizer for 2 hours (the rotating speed is 13000 rpm) to obtain sun-screening products 1-24 (wherein, sun-screening products 1-8 are sun-screening products containing sun-screening agents obtained in examples 1-8, and sun-screening products 9-24 are sun-screening products containing sun-screening agents obtained in comparative examples 1-16).

Experimental example 2 friendliness of sunscreen products 1 to 8 to skin

1. Test method

24 Subjects 18-60 years old (20 females, 4 males) were selected and randomly split into 8 groups for testing the safety of the sunscreen products 1-8. The sun-screening products 1 to 8 are respectively applied to the spot testers, the sun-screening products are applied to the inner side of the forearm of a subject by using a hypoallergenic adhesive tape, the palm is lightly pressed to enable the sun-screening products to be uniformly applied to the skin, the spot testers are removed after 24 hours, timing is started after the indentation disappears, and the skin condition of the tested area of the subject is observed according to the standard shown in table 1 at 30min, 24 hours and 48 hours.

TABLE 1

2. Test results

As a result, the skin grading grades of the sun-screening products 1 to 8 are 0 in the spot-stick tests for 30min, 24h and 48h, which shows that the sun-screening agent obtained by adopting the specific modification method has high safety and is friendly to the skin.

Experimental example 3 Sun-screening products 1 to 24 were more uniformly coated

1. Test method

Selecting 24 subjects (21 females and 3 males) aged 30-40 years old, cleaning hands and arms, drying water, standing in a room with constant temperature (19-21 ℃) and constant humidity (47% -53%) for half an hour, selecting 3 test areas with the length of 3cm multiplied by 3cm on the arms of the subjects, measuring the smoothness of the test areas by using a Visioscan VC-98 skin microscope, and measuring each test area for 3 times (taking the average value of 3 times as a result), thus obtaining the smoothness before use.

Then randomly extracting a subject which is not trained by a professional application method, respectively applying 18mg of sun-screening products to 3 test parts of each subject including the subject, wherein the sun-screening products applied to three test areas of each subject are different, and each sun-screening product is required to be applied by 3 different subjects. After the application, the subjects were still sitting for half an hour in a constant temperature (19-21 ℃) and constant humidity (47% -53%) room, and the smoothness of the test areas was measured again with Visioscan VC-98 skin microscope, 3 times per test area (the result was taken as an average of 3 times), and the smoothness after use was obtained.

2. Test results

The pre-use smoothness and post-use smoothness of the test areas using the same sunscreen product were averaged, respectively, and the change rate was calculated to obtain the results shown in table 2.

TABLE 2

	Average smoothness before use	Average smoothness after use	Rate of change
				Example 1	53.84	80.39	49.3％
Example 2	58.94	86.55	46.8％
				Example 3	52.07	76.53	47.0％
Example 4	57.97	84.12	45.1％
				Example 5	59.10	86.23	45.9％
Example 6	54.56	79.88	46.4％
				Example 7	56.78	82.96	46.1％
Example 8	55.38	81.11	46.5％
				Comparative example 1	53.03	74.21	39.9％
Comparative example 2	58.47	71.01	21.4％
				Comparative example 3	50.77	70.95	39.7％
Comparative example 4	58.20	69.91	20.1％
				Comparative example 5	58.87	72.45	23.1％
Comparative example 6	51.36	71.33	38.9％
				Comparative example 7	54.99	76.46	39.0％
Comparative example 8	58.32	80.52	38.1％
				Comparative example 9	52.68	73.89	40.3％
Comparative example 10	53.22	64.67	21.5％
				Comparative example 11	50.88	64.44	26.7％
Comparative example 12	51.08	61.43	20.3％
				Comparative example 13	54.59	74.28	36.1％
Comparative example 14	52.75	71.49	35.5％
				Comparative example 15	57.29	70.89	23.7％
Comparative example 16	50.66	60.11	18.7％

It can be seen that, compared with the sun-screening products 9 to 24 containing the sun-screening agents obtained in comparative examples 1 to 16, the sun-screening products 1 to 8 containing the sun-screening agents obtained in examples 1 to 8 have significantly higher smoothness when being smeared on the skin, i.e. are smeared more uniformly, which indicates that the invention utilizes the modifier with specific components to modify zinc oxide and titanium dioxide with specific particle diameters to finish the directional modification of the surfaces of the zinc oxide and the titanium dioxide, so that the obtained sun-screening agents can self-assemble on the skin surface to form uniform and compact sun-screening films, and uniform smearing can be easily realized without applying special and complicated smearing skills. The sun-protection film formed after application of sun-protection product 1 comprising the surface-modified titanium dioxide and zinc oxide of example 1 was significantly smoother compared to sun-protection product 24 comprising the non-surface-modified titanium dioxide and zinc oxide of comparative example 16.

Experimental example 4 Sun-screening products 1-24 have improved sun-screening ability after meeting water

1. SPF value test

(1) Test method

72 Subjects 18-60 years old (55 females and 17 males) were selected and randomized into 24 groups, each sunscreen product was tested on the back of 3 subjects, respectively. Two test areas A and B are respectively selected on the backs of 72 subjects, after each test area is smeared with 2mg/cm ² of samples (sun-proof products 1-24), the test area A is subjected to water treatment, the test area B is not subjected to water treatment, after waiting 15min, the two test areas simultaneously start ultraviolet irradiation, and then SPF values of the two test areas are respectively measured by referring to a measuring method of sun-proof cosmetic sun-proof index (SPF value) in cosmetic safety technical Specification. The water treatment method comprises the following steps: and spraying pure water mist for 3 times at a position 10cm away from the test area A, so that the test area A is uniformly distributed with the water mist.

(2) Test results

The SPF value of the test area A was recorded as the SPF value after encountering water, the SPF value of the test area B was recorded as the SPF value before encountering water, and the change rate of the SPF value before and after encountering water was calculated, and the results are shown in Table 3.

TABLE 3 Table 3

It can be seen that the sunscreen products 9 to 20, 23 to 24 comprising comparative examples 1 to 12, 15 to 16 all had significantly reduced sunscreen ability upon exposure to water, whereas the sunscreen products 1 to 8 comprising examples 1 to 8 had significantly improved sunscreen ability upon exposure to water, and the degree of improvement was significantly higher than that of the sunscreen products 21 to 22 comprising comparative examples 13 to 14. The invention is shown that the modification agent with specific components is used for modifying the zinc oxide and titanium dioxide with specific particle sizes to finish the directional modification of the surfaces of the zinc oxide and the titanium dioxide, so that the obtained sun-screening agent can be rearranged after meeting water, the sun-screening capability is not reduced and is not reversely increased, and the problems of reduced sun-screening capability caused by perspiration in the daily use process and the like are solved.

2. PFA value test

(1) Test method

72 Subjects 18-60 years old (44 females and 28 males) were selected and randomized into 24 groups, each sunscreen product was tested on the back of 3 subjects, respectively. And respectively selecting two test areas A and B on the backs of 72 subjects, smearing samples (sun-proof products 1-24) of 2mg/cm ² on each test area, wherein the test area A is subjected to water treatment, the test area B is not subjected to water treatment, waiting for 15min and then simultaneously starting ultraviolet irradiation on the two test areas, and respectively measuring PFA values of the two test areas by referring to a measuring method of a sun-proof cosmetic long-wave ultraviolet protection index (PFA value) in the cosmetic safety technical Specification. The water treatment method comprises the following steps: and spraying pure water mist for 3 times at a position 10cm away from the test area A, so that the test area A is uniformly distributed with the water mist.

(2) Test results

The PFA value of the test area a was recorded as the post-water SPF value, the PFA value of the test area B was recorded as the pre-water SPF value, and the change rate of the PFA value before and after the water was calculated, and the results are shown in table 4.

TABLE 4 Table 4

	PFA value before meeting water	PFA value after water	Rate of change
				Example 1	22.8	30.6	34.2％
Example 2	21.9	28.5	30.1％
				Example 3	22.1	28.9	30.8％
Example 4	20.1	25.2	25.4％
				Example 5	20.5	25.9	26.3％
Example 6	20.8	26.7	28.4％
				Example 7	20.7	26.5	28.0％
Example 8	21.0	26.9	28.1％
				Comparative example 1	19.5	18.6	-4.6％
Comparative example 2	19.7	16.5	-16.2％
				Comparative example 3	20.0	17.5	-12.5％
Comparative example 4	19.1	15.8	-17.3％
				Comparative example 5	18.3	15.0	-18.0％
Comparative example 6	19.4	16.0	-17.5％
				Comparative example 7	17.8	16.1	-9.6％
Comparative example 8	18.5	16.8	-9.2％
				Comparative example 9	18.2	16.6	-8.8％
Comparative example 10	15.5	10.9	-29.7％
				Comparative example 11	17.6	13.3	-24.4％
Comparative example 12	15.3	10.8	-29.4％
				Comparative example 13	17.9	19.2	7.3％
Comparative example 14	17.4	18.9	8.6％
				Comparative example 15	15.1	13.7	-9.3％
Comparative example 16	14.9	9.4	-36.9％

3. Instrument testing

(1) Test method

The sun-proof products 1 to 24 are respectively added on the fur surface of a polymethyl methacrylate (PMMA) plate, and then the finger with the latex medical fingerstall is smeared with a sample to form a uniform surface, the sample adding amount is controlled to be 1.8 to 2.2mg/cm ², and the sample does not contain bubbles. And then placing the PMMA plate in an environment with the temperature of 20-30 ℃ and the relative humidity of 40-60%, placing for 20min, and measuring the SPF value (the measurement point of each sample sheet is not less than 4 points and the result is averaged) by using an SPF instrument after instrument calibration and blank calibration, thus obtaining the SPF value before meeting water.

After the SPF value before meeting water is measured, immersing the PMMA plate in water with the hardness of 50-500 mg/L, stirring for 40min (the rotating speed is 300 rpm/min), taking out the PMMA plate, drying until the water drops on the surface of the PMMA plate disappear, and measuring the SPF value by an SPF instrument again (the measuring point of each sample is not less than 4 points, and the result is averaged), thus obtaining the SPF value after meeting water.

The results are shown in Table 5.

TABLE 5

It can be seen that the sunscreen products 9 to 20, 22 to 24 comprising comparative examples 1 to 12, 14 to 16 all had significantly reduced sunscreen ability upon exposure to water, whereas the sunscreen products 1 to 8 comprising examples 1 to 8 had significantly improved sunscreen ability upon exposure to water to a significantly higher extent than the sunscreen product 21 comprising comparative example 13. The invention is shown that the modification agent with specific components is used for modifying the zinc oxide and titanium dioxide with specific particle sizes to finish the directional modification of the surfaces of the zinc oxide and the titanium dioxide, so that the obtained sun-screening agent can be rearranged after meeting water, the sun-screening capability is not reduced and reversely increased, the problems of reduced sun-screening capability caused by perspiration in the daily use process and the like can be solved, and the problems of reduced sun-screening capability caused by a large amount of contact water in the swimming process and the like can be solved.

The invention aims at providing a uniform and compact sun-screening agent for a sun-screening film after being smeared, which has the characteristic of water-induced compact rearrangement of the sun-screening film in the use process, can further improve sun-screening performance, and has strong sun-screening performance in experiments simulating perspiration (SPF value test and PFA value test part) and swimming (instrument test part).

The above examples are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above examples, and any other changes, modifications, substitutions, combinations, and simplifications that do not depart from the spirit and principle of the present invention should be made in the equivalent manner, and the embodiments are included in the protection scope of the present invention.

Claims

1. A method of preparing a sunscreen comprising the steps of:

S1, adding titanium dioxide with the particle size of 10-100 nm into a modifier A for modification, and drying to obtain modified titanium dioxide; the modifier A consists of C2-11 silane and an organic solvent; the C2-11 silane is C2-11 triethoxysilane or C2-11 trichlorosilane, the C2-11 triethoxysilane is one or more of triethoxyethyl silane, butyl triethoxysilane, hexyl triethoxysilane, triethoxyoctyl silane and n-decyl triethoxysilane, and the C2-11 trichlorosilane is one or more of ethyl trichlorosilane, butyl trichlorosilane, hexyl trichlorosilane, octyl trichlorosilane and decyl trichlorosilane; the organic solvent is one of n-octane, n-heptane, n-hexane, n-pentane or n-butane;

S2, adding zinc oxide with the particle size of 20-200 nm into the modifier B for modification, and drying to obtain modified zinc oxide; the modifier B consists of C2-11 silane, C12-20 linear fatty acid and an organic solvent, or consists of C2-11 silane, polydimethylsiloxane and an organic solvent; the C2-11 silane is C2-11 triethoxysilane or C2-11 trichlorosilane, the C2-11 triethoxysilane is one or more of triethoxyethyl silane, butyl triethoxysilane, hexyl triethoxysilane, triethoxyoctyl silane and n-decyl triethoxysilane, and the C2-11 trichlorosilane is one or more of ethyl trichlorosilane, butyl trichlorosilane, hexyl trichlorosilane, octyl trichlorosilane and decyl trichlorosilane; the C12-20 straight-chain fatty acid is one or more of lauric acid, myristic acid, palmitic acid, stearic acid and eicosanoic acid, and the organic solvent is one of n-octane, n-heptane, n-hexane, n-pentane or n-butane; the mass ratio of the C2-11 silane to the C12-20 linear fatty acid is 1:1 to 5; the mass ratio of the C2-11 silane to the polydimethylsiloxane is 1:1 to 5;

S3, uniformly mixing the modified titanium dioxide, the modified zinc oxide and the dispersing agent to obtain the sun-screening agent; the mass ratio of the modified titanium dioxide to the modified zinc oxide is 1-5: 1.

2. The preparation method according to claim 1, wherein the mass ratio of the titanium dioxide to the modifier A in S1 is 1:1 to 10; the mass ratio of the C2-11 silane to the organic solvent is 1:1 to 10.

3. The preparation method according to claim 1, wherein the mass ratio of the zinc oxide to the modifier B of S2 is 1:1 to 25; the ratio of the total mass of the C2-11 silane and the C12-20 linear fatty acid to the mass of the organic solvent is 1:1 to 10; s2, the ratio of the total mass of the C2-11 silane and the polydimethylsiloxane to the mass of the organic solvent is 1:1 to 10.

4. A sunscreen obtainable by the process of any one of claims 1 to 3.

5. Use of a sunscreen according to claim 4 in the manufacture of a sunscreen product.

6. A sunscreen product comprising the sunscreen of claim 4.