CN110775996A - A kind of talc-loaded nano-ZnO composite anti-ultraviolet agent and preparation technology thereof - Google Patents

Abstract

The invention relates to a talc-loaded nano-ZnO composite anti-ultraviolet agent and a preparation technology thereof. The natural flaky mineral talc is used as a carrier mineral raw material, and a direct precipitation method is adopted. The first step is to weigh zinc nitrate hexahydrate and The talc mineral raw material powder is stirred and mixed in distilled water to obtain a mixed liquid of zinc nitrate hexahydrate-talc; secondly, the sodium carbonate is weighed according to the molar ratio of zinc nitrate hexahydrate and sodium carbonate of 1:1.5 to 3.5, dissolved in distilled water and added to the mixed liquid In the process, the precursor zinc carbonate-talc mixed liquid is obtained by stirring; the third is centrifugal washing to remove impurities in the mixed liquid to obtain the precursor zinc carbonate-talc mixture; the fourth is drying the mixture, the temperature is 105 ° C, and the time is 3h ~ 6h; 5 is drying the material before roasting, the heating rate is 10°C～15°C/min, the roasting temperature is 350°C～550°C, and the temperature is kept for 1h～3h to obtain the talc-loaded nano-ZnO composite anti-ultraviolet agent. The effect is obvious, the safety is good, the process is simple, the popularization and application are easy, the use is wide, and the social and economic benefits are remarkable.

Description

A kind of talc-loaded nano-ZnO composite anti-ultraviolet agent and preparation technology thereof

1. Technical field

The invention relates to a talc-loaded nano-ZnO composite anti-ultraviolet agent and a preparation technology thereof. Nano-ZnO is coated on the surface of natural flaky mineral talc by a direct precipitation method to obtain a talc-loaded nano-ZnO composite anti-ultraviolet agent, which is suitable for anti-ultraviolet materials or UV shielding materials.

2. Background technology

2.1 UV Concept

Ultraviolet (Ultraviolet, UV for short) is an electromagnetic wave with a wavelength of 200 nm to 400 nm. Ultraviolet rays in sunlight can be divided into long-wave ultraviolet UVA (320-400nm), medium-wave ultraviolet UVB (280-320nm) and short-wave ultraviolet UVC (200-280nm) according to different wavelengths. Appropriate sunlight exposure can increase the oxygen content of body 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. In severe cases, it will damage the internal organs of the body. The basic characteristics of each section of ultraviolet light are listed 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, and most of it is absorbed by the dermis of the skin, causing dermal blood vessels to dilate, showing symptoms such as redness, swelling, and blisters. Long-term exposure to UVB radiation can cause skin erythema, inflammation, skin aging, and even skin cancer in severe cases. In daily life, more than 95% of the ultraviolet rays that the skin comes into contact with 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 not only harm the human body, but also have certain damage and aging effects on coatings, plastics, inks and other polymer materials, causing the polymer materials to lose light, fade, yellow, crack, peel, embrittlement, powder densification, strength reduction and delamination. Even indoor light and sunlight transmitted through glass windows can degrade some materials.

Therefore, 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 humans, people have begun to take certain measures to shield ultraviolet rays. There are two main types of UV shielding materials for human skin protection: one is anti-UV textiles, including sunscreen clothing, sunscreen hats, sunscreen gloves, and sunscreen umbrellas. One is anti-ultraviolet coating agent, which is mainly sunscreen skin care products or cosmetics used in daily life. It uses anti-ultraviolet sunscreen agent (organic or inorganic) to cooperate with each other or compound with other ingredients to make paste or liquid. Semi-liquid products. The UV shielding materials used for the protection of polymer materials are mainly fillers with UV 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 damage to the skin. 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 UV radiation. Among them, tert-butylmethoxydibenzoylmethane is the most representative UVA ultraviolet absorber in sunscreen cosmetics, and isooctyl methoxycinnamate is the most widely used UVB ultraviolet absorber in sunscreen cosmetics. However, organic sunscreens often need to be strictly controlled in terms of heat resistance, stability, UV absorption range, toxic and side effects, etc. It only works in a single wavelength band (UVA or UVB), and may decompose and destroy under the action of light. The sunscreen effect is lost, and the effective time is short. In contrast, inorganic sunscreens (physical sunscreens) are more stable and safer. They mainly scatter UV rays while absorbing a small amount of UV rays to achieve sun protection. Due to the advantages of high efficiency, safety and durability, inorganic sunscreens are more and more widely used.

The current inorganic sunscreens (physical sunscreens) are mainly _TiO2 and ZnO, both of which are semiconductor materials, _TiO2 is mainly for UVB protection, and ZnO is mainly for UVA protection. However, the sunscreen and UV shielding effects of both are closely related to their particle size or nano-effect. The previous research results show that when the two are nanoparticles, that is, when the particle size of TiO ₂ is 30-50 nm (Zu Yong et al., 1998) and the particle size of ZnO is 10-35 nm, it exhibits outstanding nano-effect and has excellent performance. UV shielding effect of sunscreen (Yao Chao et al., 2003).

Nano ZnO is a widely used physical sunscreen agent. Its principle of shielding ultraviolet rays is to absorb and scatter ultraviolet rays. Because of its small particle size, large specific surface area, good stability, and low irritation, it has good UV shielding performance. It 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 characteristics of weak polarity and very small nanoparticles, nano-ZnO has a high surface energy, which makes the nanoparticles in a thermodynamically unstable state and tends to agglomerate, thus limiting its nano-effect and UV-shielding effect. In addition, in the manufacturing process of skin care products or cosmetics, nano-ZnO particles are difficult to disperse to the original particle size, the ultraviolet absorption effect in UVA, UVB and UVC bands is reduced, and its transparency and ultraviolet shielding properties cannot be fully exerted. Sunscreens are not as effective. To sum up, as an inorganic sunscreen agent, 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 incorporated into the emulsifier, it is very difficult to It is easy to precipitate and cause 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 produce layering phenomenon with the dispersion, and it must be shaken well before use. This not only brings inconvenience to the user, but also increases the use cost.

(3) Health problems: Nano-ZnO in sunscreen products is easy to accumulate in the stratum corneum of the human skin, the openings of the hair follicles and sebaceous glands and the wrinkles. Since the size of human facial pores is generally 20 μm, excessive use is easy to block skin pores, which is not conducive to sweating. secretion, which can easily cause skin infections. Furthermore, trace amounts of zinc may also be absorbed through the skin and enter the bloodstream, which is very detrimental to human health, especially for sunburned and damaged skin patients.

(4) Aesthetic problems: Due to the agglomeration effect of nano-ZnO, it may cause unnatural whitening when smeared on the skin, which affects the aesthetic effect.

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

(6) Price problem: Since nano-ZnO cannot be directly mixed with ordinary cosmetics, in order to overcome the phenomenon of delamination of the dispersion when used alone, small and 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 such products generally high, which limits its usage.

2.3 Status of preparation technology of nano-ZnO

According to the state of the raw materials and the preparation process, the preparation methods of nano-ZnO mainly include three types: 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. The main advantages and disadvantages are shown in Table 2.

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

2.4 Research status of 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 a certain preparation method to modify nano-ZnO and control the morphology of nano-ZnO; the other is to use minerals as a carrier to support nano-ZnO . The main research progress of predecessors is as follows:

US 6086666 discloses a method for preparing sheet-like mineral-loaded nano-ZnO anti-ultraviolet material by hydrolysis and precipitation, which is characterized in that at a certain reaction temperature, zinc source and precipitant are added to the mineral water solution for reaction, and after a certain time, filtration is carried out After drying and calcining, an anti-ultraviolet composite material is obtained, wherein the flake material can be muscovite, sericite, talc and kaolinite.

CN 104017393A discloses a method for preparing nano-ZnO-coated sericite powder composite material by direct precipitation method, which is characterized in that in an aqueous solution system, calcium hydroxide or calcium oxide is added to the mixed system of sericite powder and zinc sulfate solution , and directly obtain nano-ZnO-coated sericite powder composites. The obtained composite material has good dispersibility in organic solvents, as well as 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 talc by hydrolysis precipitation method to prepare nano-ZnO/calcined kaolin composite anti-ultraviolet powder material. When the temperature is 90℃, the modification time is 10min, the pulp concentration is 10:1, and the calcination temperature is 400℃, the composite powder material has good anti-ultraviolet performance.

From the above introduction, it can be seen that the current preparation method of mineral-loaded nano-ZnO anti-UV agent is mainly the hydrolysis precipitation method in the liquid phase method. Among them, Wan Bin et al. (2014) used the direct precipitation method to prepare nano-ZnO-coated sericite powder composite Material. However, according to the search of the inventor, there is no technical achievement report on the preparation of talc-loaded nano-ZnO composite anti-ultraviolet agent by the direct precipitation method at present.

3. Technical solutions

The purpose of the present invention is to prepare a kind of composite anti-ultraviolet agent or ultraviolet shielding material by loading nano-ZnO with the natural flaky mineral talc with layered structure as raw material, so as to overcome the easy agglomeration, delamination, etc. of existing nano-ZnO. Poor dispersion and other problems, improve the performance of sunscreen and UV shielding, improve the aesthetic effect, prevent the phenomenon of whitening, improve the use efficiency and reduce the use cost. In order to achieve the above goals, the following technical problems must be solved:

(1) Selection of carrier mineral raw materials: There are many types of layered silicate minerals. The selection conditions are: layered structure and two-dimensional habit crystals. The mineral crystals are mainly small scale-like, non-toxic and harmless. relatively abundant.

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

(3) Preparation process of nano-ZnO by direct precipitation method: On the basis of the work of (2), further experiments were carried out to determine the technological conditions of direct precipitation method to prepare nano-ZnO.

(4) Preparation process of talc-loaded nano-ZnO composite anti-ultraviolet agent: On the basis of the work of (3), further experiments were carried out to determine the technological conditions of preparing talc-loaded nano-ZnO composite anti-ultraviolet agent by direct precipitation method.

The specific technical solutions are as follows:

3.1 Selection of carrier mineral raw materials

Talc is a magnesium silicate mineral with a 2:1 trioctahedral layered structure, the crystal chemical formula is Mg ₃ [Si ₄ O ₁₀ ](OH) ₂ , and the theoretical chemical composition is MgO 31.72%, SiO ₂ 63.52% and _H2O 4.76%. Talc is monoclinic, and its crystal structure consists of two layers of [SiO ₄ ] tetrahedron and one layer of [MgO ₆ ] octahedron, with a typical 2:1 layered structure; vitreous luster, slippery, and no It is harmless and chemically stable, and meets the requirements of nano-ZnO carrier minerals.

从XRD谱图 看出，该样品含有少量的斜绿泥石。Fig. 1 is the X-ray powder crystal diffraction pattern (XRD) of the talc sample adopted in the present invention, it can be seen that the diffraction peak of this talc is sharper, indicating that the raw material talc crystal structure is complete, and the crystalline state is good, and the talc standard card (PDF: 29-1493) are basically the same, and their characteristic peaks are:

It can be seen from the XRD spectrum that the sample contains a small amount of plinochlorite.

Table 3 is the X-ray fluorescence spectrum (XRF) detection result of the chemical composition of the talc sample used in the present invention. It can be seen that the weight percentage (%) of the chemical composition of the talc sample is relatively close to its theoretical composition, and the content of other impurity components is very high. Low, does not contain toxic and harmful impurities to the human body. Combined with the XRD analysis results, it shows that the experimental sample is relatively pure, belongs to the talc single mineral aggregate, and meets the selection conditions of carrier mineral raw materials.

Table 3 X-ray fluorescence spectrum (XRF) detection results of chemical components of talc samples (unit is weight percentage, %)

name SiO₂ Al₂O₃ Fe₂O₃ TiO₂ CaO MgO K₂O Na₂O MnO P₂O₅ SO₃ H₂O content 56.70 3.89 1.85 0.26 2.45 30.33 0.01 0.04 0.02 0.11 0.01 4.33

3.2 Selection of the preparation method of nano-ZnO

According to the relevant literature, the present invention adopts the five methods shown in Table 2, respectively prepares nano-ZnO under its optimized conditions, and further detects and analyzes their ultraviolet shielding properties by using an ultraviolet-visible spectrophotometer. 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 high absorbance in the ultraviolet region, but also have a high transmittance in the visible light region. It can be seen from Figure 2 that due to the coarse particles of industrial ZnO, the UV shielding performance is poor and does not meet the requirements. At present, the standard for distinguishing the anti-ultraviolet effect of domestic products is divided into: a grade, the ultraviolet shielding rate is more than 90%; b grade, the ultraviolet shielding rate is 80%~90%; c grade, the ultraviolet shielding rate is 50%~ 80%. Anti-ultraviolet agents or ultraviolet shielding materials should generally be selected as grade a. As shown in Figure 2, because the ultraviolet shielding rate of the nano-ZnO prepared by the direct precipitation method is greater than 90%, it belongs to the class a, which meets the requirements of the present invention.

3.3 Preparation process of nano-ZnO by direct precipitation

The present invention further experiments to determine the process conditions for preparing nano-ZnO by direct precipitation method, the details are as follows:

(1) Preparation of precursor zinc carbonate liquid: Weigh a certain mass of zinc nitrate hexahydrate (Zn(NO ₃ ) ₂ ·6H ₂ O) and sodium carbonate ( Na ₂ CO ₃ ), respectively dissolved in a certain amount of distilled water, and the aqueous solution of zinc nitrate hexahydrate was magnetically stirred for 10 minutes, then the aqueous sodium carbonate solution was added to the aqueous solution of zinc nitrate hexahydrate, and the magnetic stirring was continued for 30 to 40 minutes to obtain the precursor Zinc carbonate liquid;

(2) washing and removing impurities: adopt centrifugal washing device, the precursor zinc carbonate liquid is carried out centrifugal washing, twice distilled water wash, twice dehydrated alcohol wash, remove impurity, obtain precursor zinc carbonate material;

(3) Drying material: move the precursor zinc carbonate material after washing and removing impurities into a drying device, the drying temperature is 105°C, and the drying time is 3h-6h;

(4) Roasting synthesis: using a roasting device, in an air environment, at a heating rate of 10°C to 15°C/min, the dried precursor zinc carbonate material is heated to 350°C to 550°C, and kept for 1h to 3h, that is, Obtained nano-ZnO powder.

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 the nano-ZnO prepared by the direct precipitation method. It can be seen that three standard strong peaks with sharp peak shape and high intensity appear in the range of 30°～40° diffraction angle, namely

This basically coincides with the nano-ZnO standard PDF card (36-1451). Considering that the characteristic peaks appearing in the entire angular 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 impurity peaks that cannot correspond to the standard card in the diffraction pattern, indicating that the purity of the sample is high.

Figure 4 is a photo of the SEM analysis of the nano-ZnO prepared by the direct precipitation method. It can be seen that the nano-ZnO powder grains are spherical or quasi-spherical, with the characteristics of nano-particles, and the particle size is 30nm-50nm, but there is obvious agglomeration Phenomenon.

3.4 Preparation process of talc-loaded nano-ZnO composite anti-UV agent

On the basis of the above work, further experiments were carried out to determine the process conditions for preparing the talc-loaded nano-ZnO composite anti-ultraviolet agent by the direct precipitation method, as follows:

(1) Preparation of zinc nitrate hexahydrate-talc mixed liquid: Weigh a certain mass of zinc nitrate hexahydrate (Zn(NO ₃ ) ₂ ·6H ₂ O) and talc mineral raw material powder in a mass ratio of 4:1, respectively. Water zinc nitrate is dissolved in a certain amount of distilled water, magnetically stirred for 10 minutes, then talc powder is added to it, and magnetically stirred for 30 minutes to obtain a zinc nitrate hexahydrate-talc mixed liquid;

(2) Preparation of precursor zinc carbonate-talc mixed liquid: weigh a certain mass of sodium carbonate (Na ₂ CO ₃ ) according to the molar ratio of zinc nitrate hexahydrate and sodium carbonate of 1:1.5 to 3.5, and first dissolve it in a certain amount of distilled water , and then the sodium carbonate aqueous solution is added to the zinc nitrate hexahydrate-talc mixed liquid, and the magnetic stirring is continued for 30min-40min to obtain the precursor zinc carbonate (ZnCO ₃ )-talc mixed liquid;

(3) washing and removing impurities: adopt centrifugal washing device, centrifugal washing precursor zinc carbonate-talc mixed liquid, twice distilled water washing, twice dehydrated alcohol washing, remove impurity, obtain precursor zinc carbonate-talc mixture;

(4) drying material: the precursor zinc carbonate-talc mixture after washing and removing impurities is moved into drying device, drying temperature is 105 ℃, drying time is 3h～6h;

(5) Roasting load: Using a roasting device, in an air environment, at a heating rate of 10°C to 15°C/min, heat the dried precursor zinc carbonate-talc mixture to 350°C to 550°C, and keep the temperature for 1h to 3h. , that is, the talc-loaded nano-ZnO composite anti-ultraviolet agent is obtained.

4. Technical advantages

(1) The effect is obvious. The invention uses talc as a carrier and adopts a direct precipitation method to prepare a talc-loaded nano-ZnO composite anti-ultraviolet agent. It has better performance and higher transmittance to visible light, which solves the problems of agglomeration, delamination and aesthetics of nano-ZnO.

(2) Good safety. The talc used in the present invention is a natural mineral, non-toxic and non-polluting. The raw materials and reagents used in the preparation of nano-ZnO are also non-toxic, safe and reliable.

(3) The process is simple. The direct precipitation method used in the present invention is simple to operate and convenient to work.

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

(5) Wide range of uses and significant economic and social benefits. As people gradually realize the harm of ultraviolet rays to the human body, anti-ultraviolet materials have attracted more and more attention, especially compared with chemical anti-ultraviolet agents, physical anti-ultraviolet agents are safer and more stable. The talc-loaded nano-ZnO composite anti-ultraviolet agent prepared by the invention better solves the technical problems such as the agglomeration of the current 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

Figure 1: X-ray powder crystal diffraction spectrum of the talc sample used in the present invention.

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

Figure 3: X-ray powder crystal diffraction pattern of nano-ZnO prepared by direct precipitation method.

Figure 4: Scanning electron microscope analysis photo of nano-ZnO prepared by direct precipitation method.

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

Figure 6: Scanning electron microscope analysis photos of talc (a) and talc-supported nano-ZnO anti-UV agent (b).

Figure 7: UV-Vis spectrum comparison diagram (Abs-absorbance, T-UV shielding rate) of talc, industrial ZnO, nano-ZnO, and talc-loaded nano-ZnO composite anti-UV agent.

6. Specific implementation

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

The natural flaky mineral talc is used as the carrier mineral raw material. The talc mineral raw material is a single mineral aggregate of talc (Figure 1). The crystals are irregular scales with a scale size of 2 μm to 6 μm (Figure 6a). Its chemical composition is shown in the table. As shown in 3, the talc-loaded nano-ZnO composite anti-ultraviolet agent is prepared by the direct precipitation method, and the preparation process is carried out according to the following 5 steps:

(1) Preparation of zinc nitrate hexahydrate-talc mixed liquid: Weigh a certain mass of zinc nitrate hexahydrate (Zn(NO ₃ ) ₂ ·6H ₂ O) and talc mineral raw material powder in a mass ratio of 4:1, respectively. Water zinc nitrate is dissolved in a certain amount of distilled water, magnetically stirred for 10 minutes, then talc powder is added to it, and magnetically stirred for 30 minutes to obtain a zinc nitrate hexahydrate-talc mixed liquid;

(2) Preparation of precursor zinc carbonate-talc mixed liquid: weigh a certain mass of sodium carbonate (Na ₂ CO ₃ ) according to the molar ratio of zinc nitrate hexahydrate and sodium carbonate of 1:1.5 to 3.5, and first dissolve it in a certain amount of distilled water , and then the sodium carbonate aqueous solution is added to the zinc nitrate hexahydrate-talc mixed liquid, and the magnetic stirring is continued for 30min-40min to obtain the precursor zinc carbonate (ZnCO ₃ )-talc mixed liquid;

(3) washing and removing impurities: adopt centrifugal washing device, centrifugal washing precursor zinc carbonate-talc mixed liquid, twice distilled water washing, twice dehydrated alcohol washing, remove impurity, obtain precursor zinc carbonate-talc mixture;

(4) drying material: the precursor zinc carbonate-talc mixture after washing and removing impurities is moved into drying device, drying temperature is 105 ℃, drying time is 3h～6h;

(5) Roasting load: Using a roasting device, in an air environment, at a heating rate of 10°C to 15°C/min, the dried precursor zinc carbonate-talc mixture is heated to 350°C to 550°C, and kept for 1h to 3h. , that is, the talc-loaded nano-ZnO composite anti-ultraviolet agent is obtained.

The detection result shows that the talc-loaded nano-ZnO composite anti-ultraviolet agent obtained by the method of this example has the following characteristics:

(1) Figure 5 is the X-ray powder crystal diffraction pattern of talc, nano-ZnO and talc-loaded nano-ZnO composite anti-ultraviolet agent. It can be seen that compared with talc and nano-ZnO, the XRD pattern of talc-loaded nano-ZnO composite anti-ultraviolet agent The characteristic diffraction peaks of talc and nano-ZnO can be seen in the two materials, because no new peaks are seen, indicating that the two are physically complex.

(2) Figure 6 is a scanning electron microscope (SEM) photo of talc (a) and talc-loaded nano-ZnO anti-ultraviolet agent (b). It can be seen that nano-ZnO particles are loaded on the surface of talc flakes, and the particle size distribution is relatively uniform. Spherical, the size is about 30nm ~ 50nm, which obviously improves the agglomeration phenomenon.

(3) Figure 7 is the UV-Vis spectrum comparison chart of talc, industrial ZnO, nano-ZnO, and talc-loaded nano-ZnO composite anti-ultraviolet agent. It can be seen that: first, the anti-ultraviolet properties of talc and industrial ZnO are both poor, not Meet the performance requirements of anti-ultraviolet agent. Second, compared with industrial ZnO, nano-ZnO has an obvious increase in absorbance in ultraviolet region, excellent anti-ultraviolet performance, ultraviolet shielding rate can reach 95%, and transmittance in visible light region is lower, indicating that the whiteness is lower than that of industrial ZnO. Third, compared with nano-ZnO, the absorbance of talc-loaded nano-ZnO anti-UV 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 that of the preparation of nano-ZnO, indicating its good transparency.

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

Funding project: This work is funded by the National Natural Science Foundation of China (41972039, 41572038) and the Sichuan Provincial Department of Education Funded Scientific Research Project (16TD0011).

Claims (1)

1. A talc loaded nano ZnO composite uvioresistant agent and a preparation technology thereof, which takes natural flaky mineral talc as a carrier mineral raw material and adopts a direct precipitation method to prepare the talc loaded nano ZnO composite uvioresistant agent, and is characterized in that:

(1) preparing zinc nitrate hexahydrate-talc mixed liquid: respectively weighing zinc nitrate hexahydrate (Zn (NO) with a certain mass ratio of 4:1 ₃) ₂·6H ₂O) and talc mineral raw material powder, dissolving zinc nitrate hexahydrate in a certain amount of distilled water, magnetically stirring for 10min, adding talc powder, and magnetically stirring for 30min to obtain zinc nitrate hexahydrate-talc mixed liquid;

(2) preparing a precursor zinc carbonate-talc mixed liquid:weighing a certain mass of sodium carbonate (Na) according to the molar ratio of zinc nitrate hexahydrate to sodium carbonate of 1: 1.5-3.5 ₂CO ₃) Dissolving the mixture in a certain amount of distilled water, adding a sodium carbonate aqueous solution into a zinc nitrate hexahydrate-talc mixed liquid, and continuously magnetically stirring for 30-40 min to obtain a precursor zinc carbonate (ZnCO) ₃) -a talc mixing fluid;

(3) washing to remove impurities: centrifugally washing a precursor zinc carbonate-talc mixed liquid by using a centrifugal washing device, washing with distilled water twice, washing with absolute ethyl alcohol twice, and removing impurities to obtain a precursor zinc carbonate-talc mixture;

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

(5) roasting and loading: heating the dried precursor zinc carbonate-talc mixture to 350-550 ℃ by adopting a roasting device at the heating rate of 10-15 ℃/min in an air environment, and preserving the heat for 1-3 h to obtain the talc-loaded nano ZnO composite anti-ultraviolet agent.

The talc is a magnesium silicate mineral with a 2:1 type trioctahedral layered structure, and the chemical formula of the crystal is Mg ₃[Si ₄O ₁₀](OH) ₂The characteristic peak of the X-ray powder crystal diffraction analysis is

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