CN111297710B - Muscovite loaded nano ZnO composite anti-ultraviolet agent and preparation method thereof - Google Patents

Abstract

The invention relates to a muscovite loaded nano ZnO composite uvioresistant agent and a preparation method thereof, wherein natural flaky mineral muscovite is used as a carrier mineral raw material, a room temperature solid phase synthesis method is adopted, and the 1 st step is that mixed materials are weighed and ground according to the mass ratio of the heptahydrate zinc sulfate to the muscovite mineral raw material of 2-5; 2, weighing and grinding the mixed material according to the molar ratio of zinc sulfate heptahydrate to sodium oxalate of 1-2 to prepare a precursor zinc oxalate-muscovite mixture; 3, adopting a centrifugal washing device to centrifugally wash and remove impurities in the precursor zinc oxalate-muscovite mixture; 4, drying the materials by adopting a drying device at the drying temperature of 105 ℃ for 3-6 h; and 5, roasting the load drying material by adopting a roasting device, wherein the heating rate is 10-15 ℃/min, the roasting temperature is 400-550 ℃, and the heat preservation is carried out for 2-4 h, so as to obtain the muscovite load nano ZnO composite uvioresistant agent. The method has the advantages of obvious effect, good safety, simple process, easy popularization and application, wide application and remarkable social and economic benefits.

Description

A kind of muscovite loaded nano ZnO composite anti-ultraviolet agent and preparation method thereof

1. Technical field

The invention relates to a muscovite-loaded nano-ZnO composite anti-ultraviolet agent and a preparation method thereof. The nano-ZnO is coated on the surface of the natural flaky mineral muscovite by a room-temperature solid-phase synthesis method to obtain a muscovite-loaded nano-ZnO composite anti-ultraviolet agent. , suitable for the field of anti-ultraviolet materials or ultraviolet shielding materials.

2. Background technology

2.1 Ultraviolet concept

Ultraviolet (UV for short) is an electromagnetic wave with a wavelength of 200nm to 400nm. The ultraviolet rays in sunlight can be divided into three sections according to different wavelengths: long-wave ultraviolet UVA (320-400nm), medium-wave ultraviolet UVB (280-320nm) and short-wave ultraviolet UVC (200-280nm). Appropriate sunlight can increase the oxygen content of the body's cells, reduce blood sugar and cholesterol levels, and enhance human vitality. However, excessive exposure to the sun for a long time can easily induce and aggravate various skin diseases, such as sunburn, freckles, acne, etc., and even damage the internal organs of the body in severe cases. The basic characteristics of each section of ultraviolet rays are now sorted out as shown in Table 1.

Table 1 Classification and characteristics of ultraviolet rays

Short-wave ultraviolet UVC is absorbed by the ozone layer, cannot reach the ground, and has no effect on the human body. UVB has the highest energy, most of which are absorbed by the dermis of the skin, causing dermal blood vessels to dilate, showing redness, swelling, blisters and other symptoms. If exposed to UVB for a long time, it will cause skin erythema, inflammation, skin aging, and serious skin cancer. Because in daily life, more than 95% of the ultraviolet rays that the skin is exposed to are UVA, which has strong penetrating power and can cause skin photoaging and skin cancer. In recent years, UVA has gradually attracted people's attention.

Ultraviolet rays are not only harmful to the human body, but also have certain damage and aging effects on paints, plastics, inks and other polymer materials, causing loss of light, fading, yellowing, cracking, peeling, embrittlement, and powdering of polymer materials. Phenomena such as vulcanization, strength reduction and delamination. Even indoor light and sunlight filtering through glass windows can age some materials.

It can be seen that ultraviolet rays have a non-negligible harmful effect on people's health and polymer materials, so the research and application of anti-ultraviolet agents or ultraviolet shielding materials have important practical significance.

2.2 Research and technical status of UV shielding materials

Since the harm of ultraviolet rays was discovered by human beings, people began to take certain measures to shield ultraviolet rays. There are two main types of UV shielding materials used for human skin protection: one is anti-ultraviolet textiles, including sunscreen clothing, sunscreen hats, sunscreen gloves, and sunscreen umbrellas. One is anti-ultraviolet paint, which is mainly sunscreen skin care products or cosmetics used in daily life. It uses anti-ultraviolet sunscreens (organic or inorganic) to cooperate with each other or compound with other ingredients to make paste or liquid semi-liquid product. The ultraviolet shielding materials used for the protection of polymer materials are mainly fillers with ultraviolet shielding function, but the research in this area is still relatively weak.

Anti-ultraviolet agents in skin care products or cosmetics refer to substances that can effectively absorb or scatter solar radiation and reduce skin damage. It can effectively absorb or scatter long-wave ultraviolet (UVA) and medium-wave ultraviolet (UVB) in sunlight. ). According to their protective mechanism, they can be divided into physical sunscreens and chemical sunscreens, which are usually called inorganic sunscreens and organic sunscreens respectively.

Chemical sunscreens (organic sunscreens), also known as UV absorbers, mainly refer to organic compounds that can absorb harmful ultraviolet radiation. Among them, tert-butylmethoxydibenzoylmethane is the most representative UVA segment ultraviolet absorber in sunscreen cosmetics at present, and isooctyl methoxycinnamate is the most widely used UVB segment ultraviolet absorber in sunscreen cosmetics at present. However, organic sunscreens often need to be strictly checked in terms of heat resistance, stability, UV absorption range, toxicity, etc., and they only work in a single waveband (UVA or UVB), and may decompose and cause damage under the action of light. Loss of sun protection effect, effective action time is short. In contrast, inorganic sunscreens (physical sunscreens) are more stable and safer. They absorb a small amount of ultraviolet light while mainly scattering ultraviolet rays to achieve sun protection. Due to the advantages of high efficiency, safety, and durability, inorganic sunscreens are being used more and more widely.

The current inorganic sunscreens (physical sunscreens) are mainly TiO ₂ and ZnO, both of which are semiconductor materials. TiO ₂ is mainly for UVB protection, and ZnO is mainly for UVA shielding. However, the sun protection and UV shielding effects of both are closely related to their particle size or nano-effect. Previous research results have shown that when the two are nanoparticles, that is, TiO ₂ with a particle size of 30-50nm (Zu Yong et al., 1998) and ZnO with a particle size of 10-35nm, they exhibit outstanding nano-effects and have excellent UV shielding effect of sunscreen (Yao Chao et al., 2003).

As a widely used physical sunscreen, nano-ZnO shields ultraviolet rays by absorbing and scattering ultraviolet rays. Due to its small particle size, large specific surface area, good stability, and low irritation; in addition to good UV shielding performance , also has the advantages of safety, stability, heat resistance and certain antibacterial properties, so it has been widely used in the field of sunscreen skin care products or cosmetics in recent years.

However, due to the weak polarity of nano-ZnO and the characteristics of very small nanoparticles and high surface energy, the nanoparticles are in a thermodynamically unstable state and tend to agglomerate, thereby limiting their nano-effect and ultraviolet shielding effect. Moreover, in the manufacturing process of skin care products or cosmetics, nano-ZnO particles are difficult to disperse to the original particle size, and the ultraviolet absorption effect in the UVA, UVB, and UVC bands is reduced, and its transparency and ultraviolet shielding performance cannot be fully exerted. Sunscreens don't work as well. To sum up, as an inorganic sunscreen, nano-ZnO still has the following main problems:

(1) Agglomeration problem: The surface energy of nano-ZnO is high, and the particles tend to agglomerate.

(2) Delamination problem: The emulsifier density of sunscreen products is about 0.96-1.1g/cm ³ , while the density of nano-ZnO is about 5.6g/cm ³ , so when high-density nano-ZnO is mixed with emulsifier, it is very difficult It is easy to precipitate and produce stratification. This layering phenomenon greatly limits the use efficiency of nano-ZnO materials, and cannot be directly mixed with ordinary cosmetics. If it is used alone, it will also have a layering phenomenon with the dispersion liquid, so it must be shaken well before use. This not only brings inconvenience to the user, but also increases the cost of use.

(3) Health problems: Nano-ZnO in sunscreen products tends to gather in the stratum corneum of human skin, the openings of pilosebaceous glands and wrinkles. Since the pores of the human face are generally 20 μm in size, long-term use tends to block the pores of the skin, which is not conducive to the secretion of sweat , easy to cause skin infection. Moreover, trace amounts of zinc may also be absorbed into the blood through the skin, which is very detrimental to human health, especially for patients with sunburn and damaged skin.

(4) Aesthetic problem: Due to the agglomeration of nano-ZnO, unnatural whitening may occur when applied to the skin, which affects the aesthetic effect.

(5) Environmental issues: The dissolution of Zn ²⁺ and the generation of active oxygen may have certain impacts on the environment and ecosystem, and it is not easy to recycle.

(6) Price issue: Since nano-ZnO cannot be directly mixed with ordinary cosmetics, in order to overcome the layering phenomenon of dispersion liquid when used alone, small special containers and devices must be used in actual use, which greatly increases the production and cost of physical sunscreen products. The cost of use makes the market price of this type of product generally on the high side, which limits its consumption.

2.3 Current status of preparation technology of nanometer ZnO

According to the state of raw materials and different preparation processes, the preparation methods of nano-ZnO mainly include liquid phase method, solid phase method and gas phase method. Among them, the gas phase method is not suitable for wide application due to the disadvantages of harsh reaction conditions, high production cost, and low product purity. At present, the preparation of nano-ZnO mainly adopts liquid-phase method and solid-phase method, and their main advantages and disadvantages are shown in Table 2.

Table 2 Advantages and disadvantages of the main preparation methods of nano-ZnO

2.4 Current status of research technology on mineral-loaded nano-ZnO composite anti-ultraviolet agent

To solve the problems of nano-ZnO agglomeration and delamination, we can start from two aspects: one is to use certain preparation methods to modify nano-ZnO and adjust the morphology of nano-ZnO; the other is to use minerals as carriers to load nano-ZnO . The main research progress of the predecessors is as follows:

US 6086666 discloses a method for preparing flake mineral-loaded nano-ZnO anti-ultraviolet materials by hydrolysis and precipitation, which is characterized in that zinc source and precipitant are added to the aqueous solution of minerals for reaction at a certain reaction temperature, and filtered after a certain period of time Dried and calcined to obtain an anti-ultraviolet composite material, wherein the flake material can be muscovite, sericite, talc, kaolinite.

CN 104017393A discloses a method for preparing nano ZnO-coated sericite powder composite material by room temperature solid-phase synthesis method, which is characterized in that in the aqueous solution system, calcium hydroxide or calcium hydroxide is added to the mixed system of sericite powder and zinc sulfate solution. Calcium oxide, directly obtain the composite material of nano-ZnO coated sericite powder. The obtained composite material has good dispersibility in organic solvents, and simultaneously has excellent anti-ultraviolet performance and antibacterial and deodorizing performance.

Gong Zhaozhuo, Zheng Shuilin et al. (2017) mentioned that nano-ZnO was coated on the surface of calcined kaolin by hydrolysis precipitation method to prepare nano-ZnO/calcined kaolin composite anti-ultraviolet powder material. When the temperature is 90°C, the modification time is 10min, the pulp concentration is 10:1, and the calcination temperature is 400°C, the composite powder material has good anti-ultraviolet performance.

From the above introduction, it can be known that the current preparation method of mineral-loaded nano-ZnO is mainly the liquid phase method. According to the inventor's search, there is no technical report on the preparation of muscovite-loaded nano-ZnO composite anti-ultraviolet agent by room temperature solid-phase synthesis method.

3. Technical solution

The purpose of the present invention is to prepare a composite anti-ultraviolet agent or ultraviolet shielding material by loading nano-ZnO with the natural sheet-like mineral muscovite with a layered structure, so as to overcome the easy agglomeration and layering of existing nano-ZnO , Poor dispersibility and other problems, improve sun protection and UV shielding performance, improve aesthetic effect, prevent whitening, improve use efficiency and reduce use cost. In order to achieve the above purpose, the following technical problems must be solved:

(1) Selection of carrier mineral raw materials: There are many types of silicate minerals with layered structure. The selection conditions are: layered structure and two-dimensional habit crystallization. Relatively rich.

(2) Selection of nano-ZnO preparation method: as shown in Table 2, several current methods have advantages and disadvantages respectively, and the selection conditions of the preparation method of the present invention are: non-toxic and harmless, convenient and feasible, and good effect.

(3) Preparation process of nano-ZnO by solid-phase synthesis at room temperature: Based on the work in (2), further experiments were conducted to determine the process conditions for preparing nano-ZnO by solid-phase synthesis at room temperature.

(4) Preparation process of muscovite-loaded nano-ZnO composite anti-ultraviolet agent: Based on the work in (3), further experiments were conducted to determine the process conditions for preparing muscovite-loaded nano-ZnO composite anti-ultraviolet agent by room temperature solid-phase synthesis method.

The specific technical scheme is as follows:

3.1 Selection of carrier mineral raw materials

Muscovite is a potassium-rich aluminosilicate mineral with a 2:1 dioctahedral layered structure. The crystal chemical formula is KAl ₂ [(AlSi ₃ O ₁₀ )](OH) ₂ , and the theoretical chemical composition is SiO ₂ 45.2%. , Al ₂ O ₃ 38.5%, K ₂ O 11.8%, H ₂ O 4.5%. Muscovite is a monoclinic crystal system, and its crystal structure is composed of an octahedral coordinated cation layer sandwiched between two identical [(Si,Al)O ₄ ] tetrahedral network layers, with a typical 2:1 type layered structure. Muscovite is usually in the form of flakes or plates, and forms a false hexagon or rhombus on the outside. It has good heat insulation, elasticity and toughness, stable physical and chemical properties, non-toxic and harmless, and meets the requirements of being a nano-ZnO carrier mineral.

而且，在XRD谱图上几乎没有其他杂质的衍射峰出现，说明本发明的白云母样品纯度很高。Fig. 1 is the X-ray powder crystal diffraction pattern (XRD) of the muscovite sample that the present invention adopts, as can be seen, the diffraction peak of this muscovite is sharper, illustrates that the raw material muscovite crystal structure is complete, and crystal state is good, and the muscovite standard The card (PDF: 06-0263) is basically the same, and its characteristic diffraction peaks are:

Moreover, almost no diffraction peaks of other impurities appear on the XRD spectrum, indicating that the purity of the muscovite sample of the present invention is very high.

3.2 Selection of nano-ZnO preparation method

According to related documents, the present invention adopts five kinds of methods shown in Table 2, and prepares nano-ZnO respectively under its optimized conditions, and adopts ultraviolet-visible light spectrometer to further detect and analyze their ultraviolet shielding properties, and the results are shown in Figure 2 Show.

According to the purpose and requirements of the present invention, the anti-ultraviolet agent or the ultraviolet shielding material should not only ensure a higher absorbance in the ultraviolet region, but also have a high transmittance in the visible region. It can be seen from Figure 2 that due to the coarser particles of industrial ZnO, the ultraviolet shielding performance is poor, which does not meet the requirements. At present, the standard for distinguishing the anti-ultraviolet effect of domestic products is divided into three categories according to their ultraviolet shielding rate: a level, the ultraviolet shielding rate is greater than 90%; b level, the ultraviolet shielding rate is 80% to 90%; c level, the ultraviolet shielding rate is 50% 80%. The anti-ultraviolet agent or ultraviolet shielding material should generally choose a grade. As shown in Fig. 2, since the ultraviolet shielding rate of the nano-ZnO prepared by the solid-phase synthesis method at room temperature is greater than 90%, it belongs to class a and meets the requirements of the present invention.

3.3 Preparation process of nanometer ZnO by solid phase synthesis at room temperature

Further experiments of the present invention determine the process conditions for preparing nano-ZnO by solid-phase synthesis at room temperature, specifically as follows:

(1) Preparation of precursor zinc oxalate: Weigh zinc sulfate heptahydrate (ZnSO ₄ 7H ₂ O) and sodium oxalate (Na ₂ C ₂ O ₄ ) at a molar ratio of 1 to 2:1, and grind and mix them for 30 ~40min to obtain the precursor zinc oxalate (ZnC ₂ O ₄ ·2H ₂ O);

(2) Washing and removing impurities: use a centrifugal washing device to centrifugally wash the precursor zinc oxalate, wash twice with distilled water, and wash twice with absolute ethanol to remove impurities;

(3) Drying materials: move the precursor zinc oxalate after washing and removing impurities into the drying device, the drying temperature is 105°C, and the drying time is 3h to 6h;

(4) Roasting synthesis: use a roasting device to heat the dried zinc oxalate precursor to 400°C to 550°C in an air environment at a heating rate of 10°C to 15°C/min, and keep it warm for 2h to 4h to obtain Nano ZnO.

这与纳米ZnO标准PDF卡片(36-1451)是基本重合的。考虑到整个角度衍射范围内出现的特征峰都较为尖锐，说明本纳米ZnO样品的晶型较好，结晶较为完整。同时，衍射图谱中未出现与标准卡片无法对应的杂峰，说明样品的纯度较高。Figure 3 is the X-ray powder crystal diffraction pattern of nano-ZnO prepared by solid-phase synthesis at room temperature. It can be seen that there are three standard strong peaks with sharp peak shape and high intensity in the range of 30°-40° diffraction angle. Right now

This basically coincides with the nano ZnO standard PDF card (36-1451). Considering that the characteristic peaks appearing in the whole angle diffraction range are relatively sharp, it shows that the crystal form of the nano-ZnO sample is better and the crystallization is relatively complete. At the same time, there are no miscellaneous peaks that cannot correspond to the standard card in the diffraction pattern, indicating that the purity of the sample is relatively high.

Figure 4 is a scanning electron microscope analysis photo of nano-ZnO prepared by solid-phase synthesis at room temperature. It can be seen that the nano-ZnO powder grains are spherical or spherical, with nano-particle characteristics, and the particle size is 30nm to 50nm, but the appearance is more obvious reunion phenomenon.

3.4 Preparation process of muscovite-loaded nano-ZnO composite anti-ultraviolet agent

On the basis of the above work, further experiments were conducted to determine the process conditions for preparing muscovite-loaded nano-ZnO composite anti-ultraviolet agent by room temperature solid-phase synthesis method, as follows:

(1) Preparation of zinc sulfate heptahydrate-muscovite mixture: according to the mass ratio of zinc sulfate heptahydrate (ZnSO ₄ 7H ₂ O) to the mineral raw material of muscovite 2～5:1, weigh a certain quality of zinc sulfate heptahydrate and Muscovite mineral raw material powder, and further grinding and mixing for 30-40 minutes to obtain zinc sulfate heptahydrate-muscovite mixture;

(2) Preparation of precursor zinc oxalate-muscovite mixture: Weigh a certain mass of sodium oxalate (Na ₂ C ₂ O ₄ ) according to the molar ratio of zinc sulfate heptahydrate and sodium oxalate 1 to 2:1, and add it to sulfuric acid heptahydrate In the zinc-muscovite mixture, continue grinding for 50-60 minutes to obtain the precursor zinc oxalate (ZnC ₂ O ₄ ·2H ₂ O)-muscovite mixture;

(3) Washing and removing impurities: use a centrifugal washing device to centrifugally wash the precursor zinc oxalate-muscovite mixture, wash twice with distilled water, and wash twice with absolute ethanol to remove impurities;

(4) Drying materials: move the precursor zinc oxalate-muscovite mixture after washing and removing impurities into the drying device, the drying temperature is 105°C, and the drying time is 3h to 6h;

(5) Roasting load: Use a roasting device to heat the dried precursor zinc oxalate-muscovite mixture to 400°C-550°C in an air environment at a heating rate of 10°C-15°C/min, and keep it warm for 2h- After 4 hours, the muscovite-loaded nano-ZnO composite anti-ultraviolet agent was obtained.

4. Technical advantages

(1) The effect is obvious. The present invention uses muscovite as a carrier and adopts a solid-phase synthesis method at room temperature to prepare a muscovite-loaded nano-ZnO composite anti-ultraviolet agent. The composite material has better anti-ultraviolet performance or ultraviolet shielding performance than nano-ZnO prepared separately. It has better dispersion in solvents, and has higher transmittance to visible light, which solves the problems of agglomeration, delamination, and aesthetics of nano-ZnO.

(2) Good security. The muscovite used in the present invention is a natural mineral, non-toxic and pollution-free. The raw material reagents used in the process of preparing nano-ZnO are also non-toxic, safe and reliable.

(3) The process is simple. The room temperature solid-phase synthesis method used in the present invention is simple to operate and convenient to work.

(4) It is easy to popularize and apply. The invention has the advantages of simple process, convenient operation, easy learning, mastering and popularization and application.

(5) It has a wide range of uses and significant economic and social benefits. As people gradually realize the harm of ultraviolet rays to the human body, more and more people pay attention to anti-ultraviolet materials, especially compared with chemical anti-ultraviolet agents, physical anti-ultraviolet agents are safer and more stable. The muscovite-loaded nano-ZnO composite anti-ultraviolet agent prepared by the invention better solves the current technical problems such as the agglomeration of nano-ZnO, is of great significance to the development of the anti-ultraviolet material industry, and has broad application prospects and significant economic and social benefits.

5. Description of drawings

Fig. 1: the X-ray powder crystal diffraction spectrogram of the muscovite sample that the present invention adopts.

Figure 2: UV shielding properties of nano-ZnO prepared by different methods (Abs-absorbance, T-UV shielding rate).

Figure 3: X-ray powder diffraction spectrum of nano-ZnO prepared by solid-phase synthesis method at room temperature.

Figure 4: Scanning electron microscope analysis photos of nano ZnO prepared by solid phase synthesis at room temperature.

Figure 5: X-ray powder crystal diffraction spectrum of muscovite, nano-ZnO and muscovite-loaded nano-ZnO composite anti-ultraviolet agent.

Figure 6: SEM analysis photos of muscovite (a) and muscovite-loaded nano-ZnO anti-ultraviolet agent (b).

Figure 7: Comparison of UV-visible spectra (Abs-absorbance, T-ultraviolet shielding rate) of muscovite, industrial ZnO, nano-ZnO, and muscovite-loaded nano-ZnO composite anti-ultraviolet agent.

6. Specific implementation

Example 1: A kind of muscovite-loaded nano-ZnO composite anti-ultraviolet agent and its preparation method

The natural flaky mineral muscovite is used as the carrier mineral raw material. The muscovite mineral raw material is a single mineral aggregate of muscovite (Figure 1). The ingredients are shown in Table 3. The microcrystalline muscovite-loaded nano-ZnO composite anti-ultraviolet agent was prepared by solid-phase synthesis at room temperature, and the preparation process was carried out in the following 5 steps:

(1) Preparation of zinc sulfate heptahydrate-muscovite mixture: according to the mass ratio of zinc sulfate heptahydrate (ZnSO ₄ 7H ₂ O) to the mineral raw material of muscovite 2～5:1, weigh a certain quality of zinc sulfate heptahydrate and Muscovite mineral raw material powder, and further grinding and mixing for 30-40 minutes to obtain zinc sulfate heptahydrate-muscovite mixture;

(2) Preparation of precursor zinc oxalate-muscovite mixture: Weigh a certain mass of sodium oxalate (Na ₂ C ₂ O ₄ ) according to the molar ratio of zinc sulfate heptahydrate and sodium oxalate 1 to 2:1, and add it to sulfuric acid heptahydrate In the zinc-muscovite mixture, continue grinding for 50-60 minutes to obtain the precursor zinc oxalate (ZnC ₂ O ₄ ·2H ₂ O)-muscovite mixture;

(3) Washing and removing impurities: use a centrifugal washing device to centrifugally wash the precursor zinc oxalate-muscovite mixture, wash twice with distilled water, and wash twice with absolute ethanol to remove impurities;

(4) Drying materials: move the precursor zinc oxalate-muscovite mixture after washing and removing impurities into the drying device, the drying temperature is 105°C, and the drying time is 3h to 6h;

(5) Roasting load: Use a roasting device to heat the dried precursor zinc oxalate-muscovite mixture to 400°C-550°C in an air environment at a heating rate of 10°C-15°C/min, and keep it warm for 2h- After 4 hours, the muscovite-loaded nano-ZnO composite anti-ultraviolet agent was obtained.

Detecting result shows, the muscovite loaded nanometer ZnO compound anti-ultraviolet agent obtained by this example method has following characteristics:

(1) Figure 5 is the X-ray powder crystal diffraction pattern of muscovite, nano-ZnO and muscovite-loaded nano-ZnO composite anti-ultraviolet agent, as can be seen, compared with muscovite and nano-ZnO, muscovite-loaded nano-ZnO composite anti-ultraviolet In the XRD pattern of the agent, the characteristic peaks of the two substances of muscovite and nano-ZnO can be seen. Since no new peaks are seen, it shows that the two are physically compounded.

(2) Figure 6 is a scanning electron microscope analysis (SEM) photo of muscovite (a) and muscovite-loaded nano-ZnO anti-ultraviolet agent (b). It can be seen that the surface of muscovite scales is loaded with nano-ZnO particles, and the particle size distribution is relatively large. Uniform and spherical, with a size of about 30nm to 50nm, which significantly improves the agglomeration phenomenon.

(3) Fig. 7 is the ultraviolet-visible light spectrum comparison chart of muscovite, industrial ZnO, nanometer ZnO, muscovite-loaded nanometer ZnO composite anti-ultraviolet agent, as can be seen: first, the antiultraviolet performance of muscovite and industrial ZnO is all higher Poor, does not meet the performance requirements of anti-ultraviolet agent. Second, compared with industrial ZnO, the absorbance in the ultraviolet region of nano-ZnO is significantly increased, the anti-ultraviolet performance is excellent, the ultraviolet shielding rate can reach 95%, and the transmittance in the visible light region is lower, indicating that the whiteness is lower than that of industrial ZnO. Third, compared with nano-ZnO, the absorbance of muscovite-loaded nano-ZnO anti-ultraviolet agent in the ultraviolet region is further improved, and the ultraviolet shielding rate is close to 99%, indicating that its anti-ultraviolet performance is excellent, and its transmittance to visible light is also better than The prepared nano-ZnO shows good transparency.

The above detection results show that the muscovite-loaded nano-ZnO composite anti-ultraviolet agent obtained in the embodiment of the present invention can overcome the technical problems such as the easy aggregation of existing nano-ZnO, significantly improve the anti-ultraviolet or ultraviolet shielding material performance of nano-ZnO, and has a good market Prospects and socioeconomic benefits.

Fund project: This work is funded by the National Natural Science Foundation of China (41572038, 41972039), and the Sichuan Provincial Department of Education's scientific research project (16TD0011).

Claims (1)

1. A muscovite loaded nano ZnO composite uvioresistant agent takes natural flaky mineral muscovite as a carrier mineral raw material, and is prepared by a room temperature solid phase synthesis method, which is characterized in that:

(1) Preparing a zinc sulfate heptahydrate-muscovite mixture: zinc sulfate heptahydrate (ZnSO) ₄ ·7H ₂ And O) and a muscovite mineral raw material in a mass ratio of 2 to 5, respectively weighing a certain mass of zinc sulfate heptahydrate and muscovite mineral raw material powder, and further grinding and mixing for 30min to 40min to obtain the zinc sulfate heptahydrate-muscovite mineral raw material powderMixing;

(2) Preparation of a precursor zinc oxalate-muscovite mixture: weighing a certain mass of sodium oxalate (Na) according to a molar ratio of zinc sulfate heptahydrate to sodium oxalate of 1-2 ₂ C ₂ O ₄ ) Adding the mixture into a zinc sulfate heptahydrate-muscovite mixture, and continuously grinding for 50min to 60min to obtain a precursor zinc oxalate (ZnC) ₂ O ₄ ·2H ₂ O) -muscovite mixtures;

(3) Washing to remove impurities: carrying out centrifugal washing on a precursor zinc oxalate-muscovite mixture by adopting a centrifugal washing device, washing with distilled water twice, and washing with absolute ethyl alcohol twice to remove impurities;

(4) Drying the materials: transferring the washed and impurity-removed precursor zinc oxalate-muscovite mixture into a drying device, wherein the drying temperature is 105 ℃, and the drying time is 3h to 6h;

(5) Roasting and loading: heating the dried precursor zinc oxalate-muscovite mixture to 400-550 ℃ at a heating rate of 10-15 ℃/min in an air environment by adopting a roasting device, and preserving heat for 2-4 h to obtain the muscovite loaded nano ZnO composite anti-ultraviolet agent;

the muscovite is a potassium-rich aluminosilicate mineral with a 2-type dioctahedral lamellar structure, and the crystal chemical formula is KAl ₂ [AlSi ₃ O ₁₀ ](OH) ₂ And the characteristic peak of X-ray powder diffraction analysis is d ₍₀₀₂₎ =9.9429Å、d ₍₀₀₄₎ =4.9685Å、d ₍₀₀₆₎ =3.3485Å。

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