Inorganic nano ultraviolet absorbent as well as rapid preparation method and application thereof

Abstract

The invention discloses an inorganic nano ultraviolet absorbent as well as a rapid preparation method and application thereof, and solves the problems that a nano-scale inorganic sun-screening agent generates free radicals under ultraviolet rays and is time-consuming and expensive in production by using cerous phosphate nanorods as effective components. Firstly, nano-scale cerium phosphate has the advantages of strong sunscreen capability and good transparency, does not deposit into a thicker white layer on the skin surface, and has no defects of false white and pore blockage; and secondly, compared with the production process and cost of nano titanium dioxide and zinc oxide, the nano cerium phosphate can be obtained through a simple water phase stirring method, the consumed time is short, and the cost is low. The preparation method disclosed by the invention is relatively low in cost, simple and convenient to operate and short in time consumption, and the prepared ultraviolet absorbent is high in sunscreen capability and good in transparency and can be used as a sunscreen agent independently or in a component form.

Description

Technical Field

[0001] The present invention relates to the technical field of nanomaterials, and particularly to an inorganic nano ultraviolet absorber, a rapid preparation method thereof and an application thereof. Background Art

[0002] Inorganic ultraviolet absorbers, which are physical sunscreens (pigment grade) that simply block ultraviolet rays by covering, have the advantages of high safety and good stability. However, since they deposit a relatively thick white layer on the skin surface, they are prone to clogging pores, affecting the normal secretion of sebaceous glands and sweat glands, and are also prone to falling off. Sunscreen products with a whitening effect often contain such sunscreens.

[0003] The powder particles of nano-scale inorganic sunscreens have a diameter of less than dozens of nanometers and no longer have a covering effect. Instead, they have the advantages of strong sun protection ability and good transparency. However, they also have disadvantages such as easy aggregation, poor dispersibility, and easy generation of free radicals while absorbing ultraviolet rays.

[0004] Currently, the nano-scale inorganic sunscreens mainly used are titanium dioxide and zinc oxide. These two types of inorganic sunscreens will generate free electrons under ultraviolet rays, accelerating skin aging and causing certain harm to the skin. In addition, these two types of high-quality nano-scale products need to be prepared by relatively complicated wet chemical methods and sol-gel methods, which take a long time and require a calcination process for treatment, and the cost is relatively high. Developing new inorganic nano ultraviolet absorbers can solve these problems to a certain extent.

[0005] Micron-scale cerium phosphate also has a physical sun protection ability similar to that of titanium dioxide and zinc oxide. By reducing its size and controlling its morphology, a nano-scale inorganic sunscreen with strong sun protection ability and good transparency can be obtained. In addition, nano-scale cerium phosphate can be obtained by a simple aqueous phase stirring method, which takes a short time and has a low cost. Summary of the Invention

[0006] The first object of the present invention is to provide an inorganic nano ultraviolet absorber in view of the deficiencies of existing nano-scale inorganic sunscreens. The effective component of this inorganic nano ultraviolet absorber is nano-scale cerium phosphate, which has strong sun protection ability and good transparency. It is obtained by an aqueous phase stirring method, only requires a reaction time of a few minutes, and has a low cost.

[0007] To achieve the above object, the present invention adopts the following technical solutions: An inorganic nano ultraviolet absorber, the inorganic nano ultraviolet absorber comprising cerium phosphate nanorods and water.

[0008] Preferably, for the cerium phosphate nanorods, their chemical composition is cerium phosphate, their length is less than 100 nm, and their radius is less than 20 nm.

[0009] Preferably, the nanorods have an obvious crystal structure, which can be a hexagonal crystal or a monoclinic crystal.

[0010] The second object of the present invention is to provide a rapid preparation method of an inorganic nano ultraviolet absorber, comprising the following steps: Step (1), adding phosphoric acid to a cerium salt solution under stirring conditions to form a homogeneous liquid; Step (2), controlling the environmental acidity and alkalinity through an alkaline reagent to adjust the crystal structure, morphology and size of the product; Step (3), after the reaction is completed, centrifuging the reactants to remove unreacted ions and redispersing them in water; Step (4), standing for a certain period of time to wait for the ionic reaction to reach equilibrium, and the inorganic nano ultraviolet absorber is obtained.

[0011] Preferably, the cerium salt solution used in step (1) is at least one of cerium nitrate, cerium acetate, and cerium chloride.

[0012] Preferably, the concentration of the cerium salt in step (1) is 0.1-10M.

[0013] Preferably, the molar ratio of phosphoric acid to cerium salt used in step (1) is 1:(1-1.2).

[0014] Preferably, the alkaline reagent in step (2) is ammonia water or sodium acetate, and the acidity and alkalinity are adjusted and controlled to a pH value of 0-2 through ammonia water or sodium acetate to adjust the morphology and size of the product. If the pH is too high, needle-like spherical substances will be formed, and if it is too small, the reaction and assembly will not occur.

[0015] Preferably, the reaction time in step (2) is within 10 minutes, and the standing time in step (4) is greater than 30 min. The ionic reaction equilibrium in step (4) mainly involves two aspects of equilibrium. One is the reaction of Ce 3+ and phosphate radicals to form cerium phosphate nanorods; the other is assembly. The nanorods rely on phosphate radicals to assemble into a specific structure, and both require standing for a certain period of time.

[0016] The third object of the present invention is to provide an application of an inorganic nano ultraviolet absorber in a sunscreen component, which can be used alone or as a sunscreen agent in the form of a component; The inorganic nano ultraviolet absorber includes cerium phosphate nanorods and water for dispersing the cerium phosphate nanorods, or cerium phosphate nanorods, water for dispersing the cerium phosphate nanorods, and other auxiliary components.

[0017] Therefore, the present invention has the following beneficial effects: By using cerium phosphate nanorods as the active ingredient, the present invention solves the problems of free radical generation under ultraviolet light and the time-consuming and expensive production of nanoscale inorganic sunscreens. First, nanoscale cerium phosphate has the advantages of strong sun protection ability and good transparency, and will not deposit into a thick white layer on the skin surface, without the disadvantages of false whitening and pore clogging. Second, compared with the production processes and costs of nanoscale titanium dioxide and zinc oxide, nanoscale cerium phosphate can be obtained by a simple aqueous phase stirring method, with short time consumption and low cost.

[0018] The preparation method of the present invention has low cost, simple operation and short time consumption. The prepared ultraviolet absorber has strong sun protection ability and good transparency, and can be used as a sunscreen alone or in the form of a component. Description of the Drawings

[0019] Figure 1 It is a mechanism diagram of the cerium phosphate nanorod ultraviolet absorber in Example 1.

[0020] Figure 2 It is a TEM image of the cerium phosphate nanorod ultraviolet absorber in Example 1 under dark field.

[0021] Figure 3 It is an XRD pattern of the cerium phosphate nanorod ultraviolet absorber in Example 1.

[0022] Figure 4 It is the transmittance curve of the cerium phosphate nanorod ultraviolet absorber with different concentrations in different wavelength bands in Test Example 1.

[0023] Figure 5 It is an XRD pattern of the cerium phosphate nanorod ultraviolet absorber in Example 2.

[0024] Figure 6 It is a comparison of the transmittance curves of cerium phosphate nanofibers and cerium phosphate nanorods in different wavelength bands in Example 3 (micrometer scale). Detailed Embodiments

[0025] The following further describes the present invention in conjunction with the drawings of the specification and specific embodiments. Those of ordinary skill in the art will be able to implement the present invention based on these descriptions. In addition, the embodiments of the present invention involved in the following description are usually only a part of the embodiments of the present invention, rather than all of the embodiments. Therefore, all other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0026] The following uses specific embodiments to illustrate the technical solutions of the present invention, but the protection scope of the present invention is not limited thereto. Example 1

[0027] Weigh 1.625 g of cerium nitrate hexahydrate (molecular weight 324.92, 0.006 mol) and add it to 20 mL of deionized water. Stir magnetically until dissolved. Take 0.4 mL of commercially available concentrated phosphoric acid (85%) and add it to 20 mL of deionized water, and then take 0.6 mL of ammonia water (28%) and mix them. Under the condition of vigorous stirring, slowly add the latter to the former, and stir for 3 min after the addition is completed. After the reaction is completed, centrifuge the reactants and redisperse them in water, and then let it stand for 1 h.

[0028] Figure 1 This is the mechanism diagram for the strong sun protection ability and good transparency of this material. The left figure is a schematic diagram of micron-scale cerium phosphate nanofibers. Due to the size factor (more than 1 micron), sunlight in the ultraviolet and visible light bands can be scattered; the right figure is a schematic diagram of this material. Due to the nano-scale size factor (less than 100 nm), this material has a high transmittance for visible light, but due to the intrinsic properties of cerium phosphate, it can effectively absorb ultraviolet light.

[0029] Figure 2 This is the TEM image of the cerium phosphate nanorod ultraviolet absorber in Example 1 under dark field. Figure 2 In the figure, the nanorods are assembled into a continuous dendritic structure, rather than individual nanorods being dispersed, indicating that the nanorods have a certain assembly ability.

[0030] Figure 3 This is the XRD pattern of this material, which can confirm that this material is cerium phosphate with a hexagonal crystal structure.

[0031] By replacing cerium nitrate with other cerium-containing precursors, such as cerium acetate and cerium chloride, the same product can also be obtained.

[0032] Test Example 1 By preparing ultraviolet absorbers with different concentrations in water and testing them with an ultraviolet-visible spectrophotometer, the test results under a 10 mm glass cell are as Figure 4 shown. It has a unique absorption curve at a concentration of 1 mg / mL (0.1%), and the absorption of UVB and UVC can reach more than 95%. After the concentration is further increased, the absorption of UVC can also increase significantly. Example 2

[0033] Weigh 1.625 g of cerium nitrate (molecular weight 324.92, 0.006 mol) and add it to 20 mL of deionized water. Stir magnetically until dissolved. Take 0.4 mL of commercially available concentrated phosphoric acid (85%) and add it to 20 mL of deionized water, and then take 1 mL of ammonia water (28%) and mix them. Under the condition of vigorous stirring, slowly add the latter to the former, and stir for 3 min after the addition is completed. After the reaction is completed, centrifuge the reactants and redisperse them in water, and then let it stand for 1 h.

[0034] Figure 5 This is the XRD pattern of the material, which can confirm that the material is cerium phosphate with a monoclinic crystal structure. It shows that the crystal structure can be adjusted through the solution environment to obtain nanomaterials with other crystal structures. The alkaline reagent such as ammonia water used in this invention to regulate the solution environment acts as an inducer. Besides controlling the morphology and size of the product, it also affects the crystal structure of the nanorods, controlling between the monoclinic and hexagonal crystals. Example 3

[0035] Weigh 1.625 g of cerium nitrate (molecular weight 324.92, 0.006 mol) and add it to 20 mL of deionized water, and stir magnetically until dissolved. Take 0.4 mL of commercially available concentrated phosphoric acid (85%) and add it to 20 mL of deionized water, and then mix it with 1 mL of ammonia water (28%). Under vigorous stirring, slowly add the latter to the former. After adding, ultrasonicate for 5 min, and then stir vigorously again for 1 h. When the transparency of the solution increases and the solution becomes thick, add the liquid to the reaction kettle and react at 250 °C for 24 h. After the reaction is completed, centrifuge the reactant and redisperse it in water to obtain micron-sized cerium phosphate nanofibers.

[0036] Test it with a UV-visible spectrophotometer, and compare its light transmittance and UV absorption performance with that of cerium phosphate nanorods. The results are as Figure 6 shown. The micron-sized cerium phosphate nanofibers have the absorption ability in the full spectrum and do not have excellent visible light transmittance.

Claims

1. An inorganic nano ultraviolet absorber, characterized in that, The inorganic nano ultraviolet absorber includes cerium phosphate nanorods and water; the cerium phosphate nanorods have a chemical composition of cerium phosphate, with a length less than 100 nm and a radius less than 20 nm.

2. The inorganic nano ultraviolet absorber according to claim 1, characterized in that: The crystal structure of the nanorods is hexagonal crystal or monoclinic crystal.

3. A rapid preparation method of the inorganic nano ultraviolet absorber as described in claim 1 or 2, characterized in that, It includes the following steps: Step (1): Add phosphoric acid to the cerium salt solution under stirring conditions to form a homogeneous liquid; Step (2): Control the environmental acidity and alkalinity through an alkaline reagent to adjust the crystal structure, morphology, and size of the product; Step (3): After the reaction, centrifuge the reactants to remove unreacted ions and redisperse them in water; Step (4): Let it stand for a certain period of time to wait for the ion reaction to reach equilibrium, and then the inorganic nano ultraviolet absorber is obtained.

4. The rapid preparation method of the inorganic nano ultraviolet absorber according to claim 3, characterized in that: The cerium salt solution used in step (1) is at least one of cerium nitrate, cerium acetate, and cerium chloride.

5. The rapid preparation method of the inorganic nano ultraviolet absorber according to claim 4, characterized in that: In step (1), the concentration of the cerium salt is 0.1 - 10 M, and the molar ratio of the phosphoric acid to the cerium salt used is 1:(1 - 1.2).

6. The rapid preparation method of the inorganic nano ultraviolet absorber according to claim 3, characterized in that: In step (2), the alkaline reagent is ammonia water or sodium acetate, and the acidity and alkalinity are adjusted and controlled to a pH value of 0 - 2 through ammonia water or sodium acetate.

7. The rapid preparation method of the inorganic nano ultraviolet absorber according to claim 3, characterized in that: The reaction time in step (2) is within 10 minutes.

8. The rapid preparation method of the inorganic nano ultraviolet absorber according to claim 4, characterized in that: The standing time in step (4) is greater than 30 min.

9. The application of an inorganic nano ultraviolet absorber in a sunscreen component as described in claim 1 or 2, characterized in that, It can be used alone or in the form of a component as a sunscreen.

10. The application of an inorganic nano ultraviolet absorber in a sunscreen component according to claim 9, characterized in that, The inorganic nano ultraviolet absorber has a high visible light transmittance and ultraviolet absorption ability. At a 0.1%wt content of cerium phosphate nanorods, the visible light transmittance in a 10 mm glass dish is greater than 90%, and the ultraviolet absorption rate is greater than 95%.

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