阅读说明：本技术 一种抗水防晒乳液及其制备方法 (Water-resistant sunscreen emulsion and preparation method thereof ) 是由 李海刚 于 2021-09-07 设计创作，主要内容包括：本发明提供了一种抗水防晒乳液及其制备方法,属于日化产品技术领域。本发明通过添加纳米晶可以有效提高抗水防晒乳液的抗水、防晒效果；并且,抗水防晒乳液中的纳米晶含有埃洛石纳米管,由于埃洛石纳米管具有较大的比表面积,能够为纳米二氧化铈提供较多的附着位点,从而避免了纳米二氧化铈颗粒之间的团聚；同时,在抗水防晒乳液中,埃洛石纳米管可以有效吸附在微乳液滴的表面,从而将二氧化铈纳米晶均匀分散至微乳液滴的表面,有效克服了纳米尺度的二氧化铈在乳液中易团聚的问题,进而有效提高了乳液的抗水、防晒效果；此外,本发明还添加了助悬剂,能够使附着二氧化铈纳米晶的微乳液滴稳定悬浮在体系中,提高了乳液的稳定性。(The invention provides a water-resistant sunscreen emulsion and a preparation method thereof, belonging to the technical field of daily chemical products. The water-resistant and sun-proof effect of the water-resistant sun-proof emulsion can be effectively improved by adding the nanocrystal; in addition, the nanocrystals in the water-resistant sunscreen emulsion contain halloysite nanotubes, and the halloysite nanotubes have a large specific surface area, so that more attachment sites can be provided for nano cerium dioxide, and the agglomeration among nano cerium dioxide particles is avoided; meanwhile, in the water-resistant sunscreen emulsion, the halloysite nanotubes can be effectively adsorbed on the surface of the microemulsion liquid drop, so that the cerium dioxide nanocrystals are uniformly dispersed on the surface of the microemulsion liquid drop, the problem that the nano-scale cerium dioxide is easy to agglomerate in the emulsion is effectively solved, and the water-resistant and sunscreen effects of the emulsion are effectively improved; in addition, the suspending agent is added, so that the microemulsion drops attached with the cerium dioxide nano-crystals can be stably suspended in a system, and the stability of the emulsion is improved.)

1. The water-resistant sunscreen emulsion is prepared from the following components in parts by weight: 0.5-5 parts of nanocrystal, 3-6 parts of oil phase, 9-19 parts of water, 1-6 parts of suspending agent, 0.1-0.6 part of film forming agent and 0-5 parts of humectant;

the nanocrystals include halloysite nanotubes and nano-ceria.

2. The water-resistant sunscreen emulsion according to claim 1, wherein the mass ratio of the halloysite nanotubes to the nano cerium dioxide in the nanocrystals is 1: 9-1: 19.

3. The water-resistant sunscreen lotion according to claim 1, wherein the oil phase is one or more of liquid paraffin, olive oil and octyl salicylate.

4. The water-resistant sunscreen lotion according to claim 1, wherein the suspending agent is one or more of polyvinyl alcohol, tween 80, sodium carboxymethylcellulose, methylcellulose and hyaluronic acid.

5. The water-resistant sunscreen lotion according to claim 1, wherein the humectant is one or a mixture of glycerin, propylene glycol, butylene glycol and polyethylene glycol.

6. The method for preparing the water-resistant sunscreen emulsion according to any one of claims 1 to 5, comprising the following steps:

(1) mixing the nanocrystalline with an oil phase to obtain a premixed oil phase;

(2) mixing a suspending agent, a humectant and water to obtain a premixed water phase;

(3) mixing and homogenizing the premixed oil phase obtained in the step (1) and the premixed water phase obtained in the step (2) in sequence to obtain a primary emulsion;

(4) mixing the primary emulsion obtained in the step (3) with a film-forming agent to obtain a water-resistant sunscreen emulsion;

the step (1) and the step (2) are not in sequence.

7. The method for preparing water-resistant sunscreen lotion according to claim 6, wherein the temperature for mixing in the step (3) is 45-55 ℃.

8. The method for preparing water-resistant sunscreen emulsion according to claim 6, wherein the mixing operation in the step (1) and the step (3) is stirring, the stirring speed is 1800-2200 rpm independently, and the stirring time is 2-4 min independently.

9. The method for preparing water-resistant sunscreen lotion according to claim 6, wherein the number of homogenization cycles in the step (3) is 4-8.

10. The method for preparing water-resistant sunscreen lotion according to claim 6 or 9, wherein the first stage pressure of the homogenizing cycle in step (3) is 900 to 1200bar, and the second stage pressure of the homogenizing cycle is 1800 to 2200 bar.

Technical Field

The invention relates to the technical field of daily chemical products, in particular to a water-resistant sunscreen emulsion and a preparation method thereof.

Background

The skin can be sunburned even cause color spots after being irradiated by ultraviolet rays for a long time, particularly, the ultraviolet rays are strong in summer, the sun-screening products are applied to the skin and are important for maintaining the health of the skin, and the main components of the common sun-screening products which play a role in shielding the ultraviolet rays are divided into two categories, namely inorganic compounds and organic compounds. Wherein, the organic compound ultraviolet screening agent comprises benzophenone, benzotriazole and the like, and the components have the problems of toxicity, easy decomposition and the like and have potential risks to the environment and human health; the inorganic compound ultraviolet screening agent comprises nano titanium dioxide, zinc oxide, ferric oxide, cerium dioxide, magnesium oxide and the like, and the components have the characteristics of good chemical stability, safety and no toxicity, and have wide application prospect.

At present, the performance of cerium oxide in protecting ultraviolet rays is more and more emphasized, and nano cerium dioxide has a better ultraviolet ray protection effect due to small particle size and large specific surface area, so that the preparation of nano cerium dioxide particles is one of the hot spots of the development and research of sunscreen products. So far, the preparation methods of nano cerium dioxide particles mainly include a precipitation method and a microemulsion method. The precipitation method generally uses alkali as a precipitator and hydrogen peroxide as an oxidant to accelerate Ce³⁺To Ce⁴⁺And finally, centrifugally separating and drying the prepared precipitate, and roasting at a continuously increased temperature to obtain the nano cerium dioxide. However, the nano-ceria prepared by the precipitation method is easy to agglomerate after being roasted, and is not beneficial to redispersion. The micro-emulsion method avoids the coalescence among particles by adopting different surfactant molecules for regulation and control, but the dosage of the surfactant and the solvent is more in the preparation process, and the organic matters are difficult to remove from the surfaces of the finally obtained particles, so that the impurity influence on the sunscreen emulsion is easily caused. In conclusion, the cerium dioxide nanoparticles prepared by the traditional precipitation method have an agglomeration phenomenon and are not easy to redisperse, and the nano cerium dioxide prepared by the microemulsion method has impurities such as organic matters which are not easy to remove on the surface. Therefore, the cerium dioxide nano particles with good dispersity and no impurities are difficult to prepare the cerium dioxide-containing sun-protection product.

Therefore, it is desirable to provide a sunscreen emulsion and a method for preparing the same, wherein the sunscreen emulsion has no agglomeration between particles, is easily dispersed in the emulsion, and has good water-resistant and UV-shielding effects.

Disclosure of Invention

The invention aims to provide the water-resistant sunscreen emulsion and the preparation method thereof.

In order to achieve the above object, the present invention provides the following technical solutions:

the invention provides a water-resistant sunscreen emulsion which is prepared from the following components in parts by weight: 0.5-5 parts of nanocrystal, 3-6 parts of oil phase, 9-19 parts of water, 1-6 parts of suspending agent, 0.1-0.6 part of film forming agent and 0-5 parts of humectant;

the nanocrystals include halloysite nanotubes and nano-ceria.

Preferably, the mass ratio of the halloysite nanotubes to the nano cerium dioxide in the nanocrystals is 1: 9-1: 19.

Preferably, the oil phase is one or a mixture of several of liquid paraffin, olive oil and octyl salicylate.

Preferably, the suspending agent is one or a mixture of polyvinyl alcohol, tween 80, sodium carboxymethylcellulose, methylcellulose and hyaluronic acid.

Preferably, the humectant is one or a mixture of glycerol, propylene glycol, butylene glycol and polyethylene glycol.

The invention also provides a preparation method of the water-resistant sunscreen emulsion, which comprises the following steps:

(1) mixing the nanocrystalline with an oil phase to obtain a premixed oil phase;

(2) mixing a suspending agent, a humectant and water to obtain a premixed water phase;

(3) mixing and homogenizing the premixed oil phase obtained in the step (1) and the premixed water phase obtained in the step (2) in sequence to obtain a primary emulsion;

(4) mixing the primary emulsion obtained in the step (3) with a film-forming agent to obtain a water-resistant sunscreen emulsion;

the step (1) and the step (2) are not in sequence.

Preferably, the temperature for mixing in the step (3) is 45-55 ℃.

Preferably, the mixing operation in the step (1) and the step (3) is stirring, the stirring speed is 1800-2200 rpm independently, and the stirring time is 2-4 min independently.

Preferably, the number of homogenization cycles in the step (3) is 4-8.

Preferably, the primary pressure of the homogenizing circulation in the step (3) is 900-1200 bar, and the secondary pressure of the homogenizing circulation is 1800-2200 bar.

The invention provides a water-resistant sunscreen emulsion which is prepared from the following components in parts by weight: 0.5-5 parts of nanocrystal, 3-6 parts of oil phase, 9-19 parts of water, 1-6 parts of suspending agent, 0.1-0.6 part of film forming agent and 0-5 parts of humectant; the nanocrystals include halloysite nanotubes and nano-ceria. The water-resistant and sun-proof effect of the water-resistant sun-proof emulsion can be effectively improved by adding the nanocrystal; in addition, the nanocrystals in the water-resistant sunscreen emulsion contain halloysite nanotubes, and the halloysite nanotubes have a large specific surface area, so that more attachment sites can be provided for nano cerium dioxide, and the agglomeration among nano cerium dioxide particles is avoided; meanwhile, when the cerium dioxide nanocrystals containing the halloysite nanotubes are dispersed into the emulsion, the halloysite nanotubes can be effectively adsorbed on the surface of the microemulsion droplets, so that the cerium dioxide nanocrystals are uniformly dispersed on the surface of the microemulsion droplets, the problem that the nano-scale cerium dioxide is easy to agglomerate in the emulsion is effectively solved, and the water-resistant and sun-resistant effects of the emulsion are effectively improved; in addition, the suspending agent is added, so that the microemulsion drops attached with the cerium dioxide nano-crystals can be stably suspended in a system, and the stability of the emulsion is improved.

The results of the examples show that the water-resistant sunscreen emulsion provided by the invention has no agglomeration among particles, the particles are round and smooth, and cerium dioxide nanocrystalline particles are uniformly dispersed on the surface of microemulsion droplets through transmission electron microscope observation; meanwhile, the sun protection effect detection shows that the average value of the Sun Protection Factor (SPF) of the water-resistant sun protection emulsion can reach 27.3-38.8; after soaking in water, the sun protection effect is detected again, the average value of the sun protection index SPF can still reach 16.58-36.25, and the water-resistant and sun protection effects are good.

Drawings

FIG. 1 is a scanning electron micrograph of a sample of the water-resistant sunscreen emulsion prepared according to example 1 of the present invention and comparative example 1; wherein, FIG. 1(A) is a scanning electron micrograph of a water-resistant sunscreen emulsion sample prepared in comparative example 1, and FIG. 1(B) is a scanning electron micrograph of a water-resistant sunscreen emulsion sample prepared in example 1;

FIG. 2 is a bar graph of the average sun protection index after soaking water for the water resistant sunscreen emulsion samples prepared in examples 1-2 of the present invention and comparative example 1;

FIG. 3 is a transmission electron micrograph of the nanocrystal prepared in example 1 of the present invention.

Detailed Description

The invention provides a water-resistant sunscreen emulsion which is prepared from the following components in parts by weight: 0.5-5 parts of nanocrystal, 3-6 parts of oil phase, 9-19 parts of water, 1-6 parts of suspending agent, 0.1-0.6 part of film forming agent and 0-5 parts of humectant;

the nanocrystals include halloysite nanotubes and nano-ceria.

The raw materials for preparing the water-resistant sunscreen emulsion comprise, by weight, 0.5-5 parts of nanocrystals, preferably 1-5 parts, and more preferably 3-5 parts. The water-resistant and sun-proof effect of the water-resistant sun-proof emulsion can be effectively improved by adding the nanocrystal.

In the present invention, the nanocrystals include halloysite nanotubes and nano-ceria. According to the invention, the halloysite nanotube is added into the nanocrystal, and the halloysite nanotube has a larger specific surface area, so that more attachment sites can be provided for nano cerium dioxide, and the agglomeration among nano cerium dioxide particles is avoided; meanwhile, when the nanocrystals containing the halloysite nanotubes are dispersed into the water-resistant sunscreen emulsion, the halloysite nanotubes can be effectively adsorbed on the surface of the microemulsion droplets, so that the nanocrystals are uniformly dispersed on the surface of the microemulsion droplets, the problem that nano-scale cerium dioxide is easy to agglomerate in the emulsion is effectively solved, and the water-resistant and sunscreen effects of the water-resistant sunscreen emulsion are effectively improved.

In the invention, the mass ratio of the halloysite nanotubes to the nano cerium dioxide in the nanocrystals is preferably 1: 9-1: 19, more preferably 1: 12-1: 19, and most preferably 1: 15-1: 17. According to the invention, the mass ratio of the halloysite nanotube to the nano cerium dioxide in the nanocrystal is controlled within the range, so that the nano cerium dioxide can be dispersed more fully, and the agglomeration problem of the nano cerium dioxide can be overcome.

In the present invention, the method for preparing the nanocrystal preferably includes the steps of:

(a) mixing the halloysite nanotube dispersion liquid and a cerium nitrate solution to obtain a suspension;

(b) mixing the suspension obtained in the step (a) with a hydrogen peroxide solution, and then aging to obtain pre-dispersed nano cerium dioxide;

(c) sequentially roasting and ultrasonically dispersing the pre-dispersed nano cerium dioxide obtained in the step (b) to obtain the nano crystal.

The invention preferably mixes the halloysite nanotube dispersion and the cerium nitrate solution to obtain the suspension.

In the present invention, the solvent of the halloysite nanotube dispersion is preferably deionized water. According to the invention, deionized water is selected as a solvent, so that other impurities can be avoided, and the high cleanliness of the water-resistant sunscreen emulsion is ensured.

In the invention, the concentration of the halloysite nanotube dispersion is preferably 1-5%, and more preferably 2-3%. The using amount of the halloysite nanotube dispersion liquid is not particularly limited, and the using amount of the halloysite nanotube dispersion liquid can be ensured to be within the range of the mass ratio of the halloysite nanotube to the nano cerium dioxide.

The operation of obtaining the halloysite nanotube dispersion is not particularly limited in the present invention, and the dispersion of halloysite nanotubes in a solvent may be carried out by a method for obtaining a dispersion well known to those skilled in the art. The source of the halloysite nanotubes is not particularly limited in the present invention, and commercially available products well known in the art may be used.

In the invention, the concentration of the cerium nitrate solution is preferably 0.4-0.6 mol/L, and more preferably 0.5 mol/L. The dosage of the cerium nitrate solution is not specially limited, and the dosage of the added cerium nitrate solution can be ensured to ensure that the mass ratio of the halloysite nanotube to the nano cerium dioxide is within the required range.

In the present invention, the operation of mixing the halloysite nanotube dispersion and the cerium nitrate solution is preferably stirring; the stirring speed and time are not particularly limited in the present invention, and the cerium nitrate solution can be uniformly mixed by using stirring parameters well known to those skilled in the art.

In the invention, the mixing temperature of the halloysite nanotube dispersion liquid and the cerium nitrate solution is preferably 55-65 ℃, and more preferably 60 ℃. According to the invention, the temperature of mixing is controlled within the range, so that the cerium nitrate solution and the halloysite nanotube dispersion liquid can be rapidly and uniformly mixed.

In the present invention, the atmosphere of the mixture of the halloysite nanotube dispersion and the cerium nitrate solution is preferably nitrogen. According to the invention, through mixing under the condition of nitrogen, impurities caused by contact of the mixed liquid with air can be avoided, and the nanocrystalline is ensured to have higher cleanliness.

After the suspension is obtained, the suspension is preferably mixed with a hydrogen peroxide solution and then aged to obtain the pre-dispersed nano cerium dioxide. The cerium nitrate can be fully oxidized by adding the hydrogen peroxide solution; meanwhile, the nano cerium dioxide can be fully attached to the surface of the halloysite nanotube through aging, so that the nano cerium dioxide can be effectively dispersed.

The concentration and the addition amount of the hydrogen peroxide solution are not particularly limited, and the cerium nitrate can be sufficiently oxidized into cerium dioxide. The mixing operation is not particularly limited in the present invention, and the suspension and the hydrogen peroxide solution can be uniformly mixed by a mixing operation known to those skilled in the art.

In the present invention, the aging is preferably performed under an alkaline condition, and more preferably at a pH of 9 to 10. In the present invention, the operation of adjusting the basic condition is preferably dropwise adding ammonia water. The concentration and the addition amount of the ammonia water and the dropping speed of the ammonia water are not particularly limited in the invention, and the alkaline condition can be achieved by adopting a mode well known by the technical personnel in the field. According to the invention, the silicate component in the halloysite nanotube can form gel through aging under an alkaline condition, so that a richer space network structure is obtained, and the nano cerium dioxide is fully dispersed.

In the invention, the aging temperature is preferably 65-75 ℃, and more preferably 70 ℃; the aging time is preferably 3.5-4.5 h, and more preferably 4 h. The invention is more beneficial to the full diffusion of the nano cerium dioxide in the system by controlling the aging temperature and the aging time within the range, and realizes the full contact and uniform mixing with the halloysite nanotube.

In the invention, the aging process preferably comprises suction filtration, deionized water washing and constant temperature drying at 85 ℃ in sequence.

After the pre-dispersed nano cerium dioxide is obtained, the pre-dispersed nano cerium dioxide is preferably roasted and ultrasonically dispersed in sequence to obtain the nano crystal.

In the invention, the roasting temperature is preferably 450-550 ℃, and more preferably 500 ℃; the roasting time is preferably 6-8 hours, and more preferably 6.5-7.5 hours. According to the invention, the roasting temperature and time are controlled within the range, so that the gas adsorbed in the halloysite nanotube can be removed sufficiently, and the dispersibility of the nano cerium dioxide and the cleanliness of the nano crystal can be improved.

In the present invention, the ultrasonic dispersion preferably uses deionized water as a solvent; the power of the ultrasonic dispersion is preferably 230-260W, and more preferably 250W; the time for ultrasonic dispersion is preferably 25-35 min, and more preferably 30 min. The invention can further improve the dispersibility of the nanocrystalline by controlling the power and time of ultrasonic dispersion within the above range.

In the present invention, it is also preferable to include spray drying after the ultrasonic dispersion. The operation of the spray drying is not particularly limited in the present invention, and a spray drying operation known to those skilled in the art may be employed. The invention can further improve the dispersibility of the nanocrystalline by adopting spray drying.

The preparation method is adopted to prepare the nano-crystal, so that the problem of agglomeration of nano-cerium dioxide is better solved, and the nano-crystal containing the nano-cerium dioxide is uniformly dispersed in the water-resistant sunscreen emulsion, thereby being more beneficial to improving the water-resistant and sunscreen effects of the water-resistant sunscreen emulsion.

The raw materials for preparing the water-resistant sunscreen emulsion comprise 3-6 parts of oil phase, preferably 3-5 parts, and more preferably 3.5-4.5 parts by weight of nanocrystalline. According to the invention, by adding the oil phase and controlling the content of the oil phase within the range, the oil phase can be in a dispersed phase in the emulsion, and the nano-crystals can be more favorably and uniformly attached to the surfaces of the micro-droplets of the dispersed phase, so that the nano-crystals are uniformly and dispersedly distributed in the water-resistant sunscreen emulsion, and the water-resistant and sunscreen effects of the water-resistant sunscreen emulsion can be more favorably improved.

In the invention, the oil phase is preferably one or a mixture of liquid paraffin, olive oil and octyl salicylate. The invention is more beneficial to forming uniform and stable water-resistant sunscreen emulsion by selecting the oil phase.

The raw materials for preparing the water-resistant sunscreen emulsion comprise, by weight, 9-19 parts of water, preferably 12-18 parts of water, and more preferably 15 parts of water. According to the invention, by adding water and controlling the content of the water and the sun protection agent within the range, the water and the sun protection agent can be used as a continuous phase in the emulsion, more auxiliaries can be dissolved, and the fluidity of the water and sun protection emulsion is improved.

In the present invention, the water is preferably deionized water.

The raw materials for preparing the water-resistant sunscreen emulsion comprise 1-6 parts by weight of a suspending agent, preferably 2-4 parts by weight of a suspending agent, and more preferably 3-4 parts by weight of a nanocrystal. The invention is more beneficial to improving the dispersion degree of a dispersed phase in the water-resistant sunscreen emulsion and keeping the water-resistant sunscreen emulsion stable by adding the suspending agent and controlling the content of the suspending agent in the range.

In the invention, the suspending agent is preferably one or a mixture of polyvinyl alcohol, tween 80, sodium carboxymethyl cellulose, methyl cellulose and hyaluronic acid. The invention is more favorable for improving the stability of the water-resistant sunscreen emulsion and avoiding the sedimentation of the nanocrystal in the water-resistant sunscreen emulsion by selecting the suspending agent.

The raw materials for preparing the water-resistant sunscreen emulsion comprise 0.1-0.6 part of film-forming agent, preferably 0.1-0.4 part of film-forming agent, and more preferably 0.2-0.3 part of nano-crystalline by weight. The film forming agent is added, so that the water-resistant sunscreen emulsion can be quickly coated on the surface of skin to form a film, the water resistance of the water-resistant sunscreen emulsion can be effectively improved, and meanwhile, the film is attached to the surface of the skin to effectively block ultraviolet irradiation on the skin, so that a good sunscreen effect is achieved.

In the invention, the film forming agent is preferably one or a mixture of more of polyurethane-34 dispersion liquid, acrylic copolymer dispersion liquid and polyester-5. The water-resistant sunscreen emulsion can have better water-resistant and sunscreen effects by selecting the film forming agent. In the present invention, the solvent of the polyurethane-34 dispersion and the acrylic copolymer dispersion is preferably deionized water; the solids content of the polyurethane-34 dispersion is preferably 40%; the acrylic acid (ester) based copolymer dispersion liquid preferably has a solid content of 30%.

The raw materials for preparing the water-resistant sunscreen emulsion comprise 0-5 parts by weight of humectant, preferably 1-4 parts by weight of humectant, and more preferably 2-3 parts by weight of nanocrystal. The moisturizing agent is added, so that the water-resistant sunscreen emulsion can keep the skin moist after forming a film on the surface of the skin, and the binding force between a sunscreen film layer and the skin is improved, thereby improving the water resistance and the lasting sunscreen effect of the water-resistant sunscreen emulsion.

In the invention, the humectant is preferably one or a mixture of glycerol, propylene glycol, butanediol and polyethylene glycol. The invention is more suitable for the skin surface and has lower volatility by selecting the humectant, which is more favorable for keeping the skin surface moist and enabling the water-resistant sunscreen emulsion film layer to be attached to the skin surface for a long time.

The water-resistant sunscreen emulsion provided by the invention has no agglomeration among particles, is easy to disperse in the water-resistant sunscreen emulsion, has a good ultraviolet shielding effect and a good water-resistant effect, can resist washing of sweat, and can reach a higher sunscreen index after being soaked in water.

The invention also provides a preparation method of the water-resistant sunscreen emulsion, which comprises the following steps:

(1) mixing the nanocrystalline with an oil phase to obtain a premixed oil phase;

(2) mixing a suspending agent, a humectant and water to obtain a premixed water phase;

(3) mixing and homogenizing the premixed oil phase obtained in the step (1) and the premixed water phase obtained in the step (2) in sequence to obtain a primary emulsion;

(4) mixing the primary emulsion obtained in the step (3) with a film-forming agent to obtain a water-resistant sunscreen emulsion;

the step (1) and the step (2) are not in sequence.

According to the invention, the nano-crystal and the oil phase are mixed to obtain the premixed oil phase.

In the present invention, the operation of mixing the nanocrystal with the oil phase is preferably stirring; the stirring speed is preferably 1800-2200 rpm, more preferably 1900-2100 rpm, and most preferably 2000 rpm; the stirring time is preferably 2-4 min, and more preferably 3 min. The invention mixes by selecting a stirring mode and controls the speed and the time within the range, thereby being more beneficial to improving the mixing uniformity of the nanocrystalline and the oil phase.

The invention mixes the suspending agent, the humectant and water to obtain the premixed water phase.

In the present invention, the operation of mixing the suspending agent, the humectant and the water is preferably stirring. The time of the stirring rate is not particularly limited in the present invention, and the suspending agent, the humectant and the water can be uniformly mixed by using stirring parameters well known to those skilled in the art.

The steps of obtaining the premixed oil phase and the steps of obtaining the premixed water phase are not in sequence.

After the premixed oil phase and the premixed water phase are obtained, the premixed oil phase and the premixed water phase are sequentially mixed and homogenized for circulation to obtain the primary emulsion.

In the invention, the mixing temperature of the premixed oil phase and the premixed water phase is preferably 45-55 ℃, and more preferably 50 ℃. By controlling the mixing temperature within the above range, the present invention can emulsify the oil phase better and form a uniformly dispersed phase in the water phase.

In the present invention, the operation of mixing the premixed oil phase and the premixed water phase is preferably stirring; the stirring speed is preferably 1800-2200 rpm, more preferably 1900-2100 rpm, and most preferably 2000 rpm; the stirring time is preferably 2-4 min, and more preferably 3 min. The invention adopts a mixing mode of stirring and controls the speed and the time within the range, thereby being more beneficial to improving the uniform dispersion of the microemulsion liquid drops attached with the nano-crystals in the water-resistant sunscreen emulsion.

In the present invention, the number of homogenization cycles is preferably 4 to 8, more preferably 5 to 7, and most preferably 6. The invention is more beneficial to the oil phase to fully form emulsified small drops in the water phase by carrying out homogeneous circulation and controlling the circulation times within the range, thereby obtaining stable and uniform emulsification effect.

In the invention, the primary pressure of the homogenizing circulation is preferably 900-1200 bar, more preferably 950-1150 bar, and most preferably 1000-1100 bar; the secondary pressure of the homogenisation cycle is preferably 1800 to 2200bar, more preferably 1900 to 2100bar, most preferably 2000 bar. The invention can make the grain diameter of the microemulsion liquid drop of the water-resistant sunscreen emulsion smaller by controlling the first-stage pressure and the second-stage pressure of the uniform circulation, thereby improving the contact surface area of the microemulsion liquid drop and the nanocrystal, being more beneficial to improving the dispersity of the nanocrystal, simultaneously, the microemulsion liquid drop with smaller grain diameter is more stable, and can be fully contacted with the skin after being coated on the surface of the skin to form a stable film, thereby achieving better water-resistant and sunscreen effects.

After the primary emulsion is obtained, the primary emulsion is mixed with the film-forming agent to obtain the water-resistant sunscreen emulsion.

The mixing operation is not particularly limited in the present invention, and the primary emulsion and the film-forming agent are uniformly mixed by a mixing operation known to those skilled in the art.

The water-resistant sunscreen emulsion prepared by the preparation method provided by the invention has better stability and dispersibility, and is more beneficial to overcoming the agglomeration problem of nanocrystals; meanwhile, the preparation method is simple and easy to implement, safe and controllable, and lower in cost.

The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

The water-resistant sunscreen emulsion is prepared from the following components in parts by weight: 1.5 parts of nanocrystalline (the mass ratio of the halloysite nanotube to the nano cerium dioxide is 1:14), 4 parts of oil phase (octyl salicylate), 15 parts of water (deionized water), 3 parts of suspending agent (2.5 parts of polyvinyl alcohol and 0.5 part of sodium carboxymethylcellulose), 0.2 part of film forming agent (polyurethane-34 dispersion liquid, the solvent of which is deionized water and the solid content of which is 40%), and 2 parts of humectant (glycerin).

The preparation method of the water-resistant sunscreen emulsion comprises the following steps:

(1) mixing the nanocrystalline and the oil phase for 2min in a stirring manner of 2000rpm to obtain a premixed oil phase;

the preparation method of the nanocrystalline comprises the following steps:

(a) mixing 1000mL of halloysite nanotube dispersion (with the mass concentration of 3% and the solvent of deionized water) and 4880mL of cerium nitrate solution (with the concentration of 0.5mol/L and the solvent of deionized water) in a stirring manner at 60 ℃ under the nitrogen atmosphere to obtain a suspension;

(b) mixing the suspension obtained in the step (a) with a hydrogen peroxide solution, aging for 4 hours at 70 ℃ under an alkaline condition, and then sequentially carrying out suction filtration, deionized water washing and constant-temperature drying at 85 ℃ to obtain pre-dispersed nano cerium dioxide; wherein, the alkaline condition of aging is pH 9 (adjusted by dropping ammonia water);

(c) sequentially roasting, ultrasonically dispersing and spray drying the pre-dispersed nano cerium dioxide obtained in the step (b) to obtain nano crystals; wherein the roasting temperature is 500 ℃, and the roasting time is 7 hours; the ultrasonic dispersion power is 250W, and the ultrasonic dispersion time is 30 min.

(2) Mixing the suspending agent, the humectant and water in a stirring manner to obtain a premixed water phase;

(3) mixing and homogenizing the premixed oil phase obtained in the step (1) and the premixed water phase obtained in the step (2) in sequence to obtain emulsion; wherein the mixing method is stirring at 2000rpm for 2min at 50 deg.C, and homogenizing for 5 times (first stage pressure 1000bar, second stage pressure 2000 bar);

(4) mixing the emulsion obtained in the step (3) with a film-forming agent to obtain a water-resistant sunscreen emulsion;

the step (1) and the step (2) are not in sequence.

Example 2

The raw material composition of the water-resistant sunscreen emulsion in the example 1 is replaced by: the compound is prepared from the following components in parts by weight: 1.5 parts of nanocrystalline (the mass ratio of the halloysite nanotube to the nano cerium dioxide is 1:14), 4 parts of oil phase (octyl salicylate), 15 parts of water (deionized water), 3 parts of suspending agent (2.5 parts of polyvinyl alcohol and 0.5 part of sodium carboxymethylcellulose) and 2 parts of humectant (glycerol). The preparation method adopts the same preparation method as the example 1 to prepare the water-resistant sunscreen emulsion.

Example 3

The raw material composition of the water-resistant sunscreen emulsion in the example 1 is replaced by: the compound is prepared from the following components in parts by weight: 0.5 part of nanocrystalline (the mass ratio of the halloysite nanotube to the nano cerium dioxide is 1:14), 3 parts of oil phase (octyl salicylate), 9 parts of water (deionized water), 1 part of suspending agent (0.5 part of polyvinyl alcohol and 0.5 part of sodium carboxymethylcellulose), 0.1 part of film forming agent (polyurethane-34 dispersion liquid, the solvent of which is deionized water and the solid content of which is 40%), and 1 part of humectant (glycerin). The preparation method adopts the same preparation method as the example 1 to prepare the water-resistant sunscreen emulsion.

Example 4

The raw material composition of the water-resistant sunscreen emulsion in the example 1 is replaced by: the compound is prepared from the following components in parts by weight: 5 parts of nanocrystalline (the mass ratio of the halloysite nanotube to the nano cerium dioxide is 1:14), 6 parts of oil phase (octyl salicylate), 19 parts of water (deionized water), 6 parts of suspending agent (3 parts of polyvinyl alcohol and 3 parts of sodium carboxymethylcellulose), 0.6 part of film forming agent (polyurethane-34 dispersion liquid, the solvent of which is deionized water and the solid content of which is 40%), and 5 parts of humectant (glycerin). The preparation method adopts the same preparation method as the example 1 to prepare the water-resistant sunscreen emulsion.

Example 5

The raw material composition of the water-resistant sunscreen emulsion in the example 1 is replaced by: the compound is prepared from the following components in parts by weight: 3 parts of nanocrystalline (the mass ratio of the halloysite nanotube to the nano cerium dioxide is 1:14), 3 parts of oil phase (octyl salicylate), 12 parts of water (deionized water), 3 parts of suspending agent (2 parts of polyvinyl alcohol and 1 part of sodium carboxymethylcellulose), 0.4 part of film forming agent (polyurethane-34 dispersion liquid, the solvent of which is deionized water and the solid content of which is 40%), and 3 parts of humectant (glycerin). The preparation method adopts the same preparation method as the example 1 to prepare the water-resistant sunscreen emulsion.

Comparative example 1

The raw material composition of the water-resistant sunscreen emulsion in the example 1 is replaced by: the compound is prepared from the following components in parts by weight: 4 parts of oil phase (octyl salicylate), 15 parts of water (deionized water), 3 parts of suspending agent (2.5 parts of polyvinyl alcohol and 0.5 part of sodium carboxymethylcellulose), 0.2 part of film forming agent (polyurethane-34 dispersion liquid, wherein the solvent is deionized water and the solid content is 40 percent) and 2 parts of humectant (glycerin). The preparation method adopts the same preparation method as the example 1 to prepare the water-resistant sunscreen emulsion.

Performance detection

Scanning electron microscope observation is carried out on the water-resistant sunscreen emulsion prepared in the example 1 and the comparative example 1, and the result is shown in figure 1; wherein, FIG. 1(A) is a scanning electron micrograph of a water-resistant sunscreen emulsion sample prepared in comparative example 1, and FIG. 1(B) is a scanning electron micrograph of a water-resistant sunscreen emulsion sample prepared in example 1;

as can be seen from FIG. 1, the water-resistant sunscreen emulsion prepared in comparative example 1 in FIG. 1(A) is round and smooth, while the surface of the liquid drop of the cerium oxide nano-crystalline water-resistant sunscreen emulsion prepared in example 1 in FIG. 1(B) has many nano-crystalline particles uniformly adhered, which indicates that the nano-crystalline particles are uniformly dispersed on the surface of the emulsion drop and no nano-crystalline agglomeration occurs.

The sun protection factor of the water-resistant sunscreen emulsion samples prepared in examples 1 to 5 and comparative example 1 of the present invention was measured by an SPF-290AS sun protection factor analyzer, and the sun protection factor was measured again after soaking in water, with the results shown in table 1 and fig. 2.

TABLE 1 sunscreen coefficient test results for the water-resistant sunscreen emulsion samples prepared in examples 1-5 and comparative example 1

As shown in Table 1, the sun protection effect test shows that the average value of the SPF of the water-resistant sun protection emulsion provided by the invention can reach 27.3-38.8, and the water-resistant sun protection emulsion has a good effect of blocking ultraviolet rays.

As can be seen from FIG. 2, the average value of the SPF of the sun protection factor still reaches 16.58-36.25 when the sun protection effect is tested again after the embodiments 1-3 are soaked in water, and the water-resistant and sun protection effects are good. The Sun Protection Factor (SPF) is obviously reduced after water enters the sun protection agent without adding the film forming agent in the example 2, the sun protection factor of the comparative example 1 without adding the nanocrystal is 12.8-13.8, and the sun protection factor is obviously reduced compared with the sun protection factor of the example 1.

The nanocrystals prepared in example 1 were observed by transmission electron microscopy, and the results are shown in fig. 3.

As can be seen from FIG. 3, the nanocrystals prepared in example 1 were irregular particles having a particle size of 30. + -.5 nm.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.