A bismuth oxychloride-based composite material, a preparation method therefor, and use thereof

Abstract

This invention discloses a bismuth oxychloride-based composite material with enhanced ultraviolet light blocking efficiency, its preparation method, and its applications. The bismuth oxychloride-based composite material is composed of metallic bismuth nanocrystals and a zinc-doped bismuth oxychloride matrix. The preparation method includes the following steps: preparation of a bismuth nanocrystal precursor; co-precipitation and crystal development of the bismuth nanocrystals and the zinc-doped bismuth oxychloride composite material; and cleaning and drying to obtain the target bismuth nanocrystal-modified bismuth oxychloride-based composite material, namely, the Bi@Zn-BiOCl composite material. Compared with traditional bismuth oxychloride powder, the Bi@Zn-BiOCl composite material exhibits an ultraviolet light blocking efficiency higher than 95%. Furthermore, the preparation of the Bi@Zn-BiOCl composite material involves mild reaction conditions, a short process, low energy consumption, and supernatant recovery, making it environmentally friendly. The Bi@Zn-BiOCl composite material prepared by this invention possesses excellent ultraviolet light blocking properties, photostability, and pearly luster, and has broad market application prospects.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor composite material technology, specifically relating to a bismuth oxychloride-based composite material, its preparation method, and its uses. Background Technology

[0002] Ultraviolet (UV) light, due to its short wavelength and high energy, is insidious and cumulative, easily causing acute damage and chronic cumulative diseases to biological tissues (skin, eyes, etc.), as well as aging and damage to polymer materials. Common UV blockers fall into two categories: organic UV absorbers such as benzophenones, benzotriazoles, methoxycinnamic acids, and triazines; and inorganic scattering UV blockers such as titanium dioxide, zinc oxide, or cerium oxide. Organic UV absorbers have significant biotoxicity, poor weather resistance, and can lead to primary microplastic pollution and accumulation in organisms, limiting their practical applications. Cerium oxide is expensive and difficult to control in size, hindering its widespread use. Titanium dioxide and zinc oxide exhibit excellent UV photocatalytic performance, requiring heavy coating to meet UV blocking requirements (ZL202080017825.8).

[0003] Bismuth oxychloride (BiOCl) possesses a unique layered structure with a band gap of approximately 3.50 eV, effectively blocking ultraviolet light with wavelengths λ≤354 nm, but exhibiting extremely low blocking efficiency for ultraviolet light with wavelengths of 358–400 nm. Compared to titanium dioxide and zinc oxide, while bismuth oxychloride offers advantages such as good biocompatibility and skin affinity, its effective blocking efficiency for ultraviolet light below 400 nm remains low.

[0004] Bismuth oxychloride lamellar structures with unique morphologies possess excellent gloss, making them a new generation of pearlescent pigments that can replace mica-based, alumina-based, and basic lead carbonate-based pearlescent pigments. However, bismuth oxychloride crystals themselves have poor photostability and are prone to turning grayish-black on the surface after exposure to natural light. Major international manufacturers of bismuth oxychloride pearlescent pigments, such as BASF and Merck, have improved the photostability of bismuth oxychloride through methods such as coating with amorphous carbon, polymers, and metal oxides (patent applications 202011456550.6 and 202210082933.4). Domestically, some manufacturers have improved photostability by modifying the microstructure of bismuth oxychloride (patent ZL201811177689.X).

[0005] Therefore, developing bismuth oxychloride-based composite materials that combine high UV blocking rate, strong photostability, and high pearl luster is an urgent need to address the problems of excessive functional additives and serious primary microplastic pollution in cosmetics, pigments, and other fields, and is also a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] The purpose of this invention is to "overcome the shortcomings of existing technologies in that they cannot simultaneously achieve ultraviolet light blocking, photostability, and pearly luster," and to provide a bismuth oxychloride-based composite material with a short process flow, low cost, and no need to introduce organic coating agents, as well as its preparation method and applications.

[0007] To achieve one or all of the above-mentioned technical objectives, this invention broadens the ultraviolet light blocking range of bismuth oxychloride by modifying its sheet structure with bismuth nanocrystals; improves the photostability of bismuth oxychloride by introducing defect energy levels through zinc doping; and regulates the microstructure of the final product, a bismuth nanocrystal-modified bismuth oxychloride-based composite material (Bi@Zn-BiOCl composite material), to give it excellent gloss. This invention provides the following technical solutions: The first aspect of the present invention provides a bismuth oxychloride-based composite material (i.e., Bi@Zn-BiOCl composite material), wherein the composite material is composed of metallic bismuth nanocrystals and a bismuth oxychloride matrix, and its ultraviolet light blocking rate is ≥95%; Furthermore, the Bi@Zn-BiOCl composite material exhibits an expanded ultraviolet light absorption threshold of 365~385 nm, a brightness of 4.5~15.3, and a stable duration of ≥32 h to resist discoloration under natural light irradiation; A second aspect of the present invention provides a method for preparing the above-mentioned bismuth oxychloride-based composite material, comprising the following steps: S01. Preparation of precursor of metallic bismuth nanocrystals: A bismuth-containing compound was added to an acidic solution and stirred until completely dissolved. Then, bismuth powder, surfactant and zinc salt were added in sequence and etched at room temperature to obtain a suspension A containing bismuth nanocrystals. S02. Coprecipitation and crystal development: Under continuous stirring at a certain temperature, a chlorine source is added to deionized water and completely dissolved. Then, suspension A is slowly added, along with a precipitant, to maintain the pH of the mixture within a certain range. After suspension A is added, the mixture is stirred continuously for a certain time to crystallize, and finally, a white precipitate is obtained. S03. Cleaning and drying: The white precipitate is filtered and separated from the liquid, the supernatant is recycled, the white precipitate is washed with deionized water until neutral, and dried to obtain the finished bismuth oxychloride-based composite material.

[0008] Furthermore, in step S01, the acidic solution is selected from any one or both of hydrochloric acid and nitric acid; even further, the concentration of the hydrochloric acid solution is 1.50~5.00 mol·L⁻¹. -1 Furthermore, the concentration of the nitric acid solution is 0.05~1.00 mol·L⁻¹. -1 ; Furthermore, in step S01, the bismuth powder has a particle size of 0.1~5 μm; Furthermore, in step S01, the bismuth-containing compound is selected from any one or more of bismuth oxide, bismuth nitrate pentahydrate, bismuth nitrate, and bismuth chloride; Furthermore, in step S01, the zinc salt is selected from any one or more of zinc chloride, zinc sulfate, and zinc oxide; Furthermore, in step S01, the surfactant is selected from any one or more of sodium dodecylbenzenesulfonate, polyethylene glycol, polyvinylpyrrolidone, and citric acid; Furthermore, in step S01, the corrosion time is 60–140 min; Furthermore, in step S01, the ratio of bismuth-containing compound: acidic solution: bismuth powder: surfactant: zinc salt is: 3~20 mmol: 10~20 mL: 0.01~0.2 mmol: 0.1~0.5 g: 1~10 mmol; Furthermore, in step S02, the temperature for co-precipitation and crystal development is 50~95℃; Furthermore, in step S02, the chlorine source is selected from any one or more of hydrochloric acid, sodium chloride, and potassium chloride; Furthermore, in step S02, the precipitant is selected from any one or more of ammonia, sodium hydroxide, potassium hydroxide, urea, and ammonium chloride; Furthermore, in step S02, the pH value is maintained within the range of 0.80 to 6.20; Furthermore, in step S02, the crystallization heat preservation time is 1 to 6 hours; Furthermore, in step S02, the ratio of deionized water: suspension A: chlorine source is 40~120 mL: 20 mL: 7.5~20 mmol; The third aspect of the present invention provides the use of any of the above-mentioned Bi@Zn-BiOCl composite materials in the preparation of ultraviolet light blocking agents or ultraviolet light blocking pigments.

[0009] Compared with the prior art, the beneficial effects of the present invention include: (1) To address the shortcomings of existing bismuth oxychloride (BOCl) composite materials with low UV absorption threshold and low UV blocking efficiency, the bismuth quantum dot-modified BOCl-based composite material (Bi@Zn-BiOCl composite material) provided in this invention uses zinc-doped BOCl as a substrate. The zinc doping amount is adjustable and can be used to control the UV blocking efficiency of BOCl. By loading bismuth nanocrystals onto the BOCl substrate, the size and loading amount of bismuth nanocrystals are adjustable and can be used to control the absorption threshold and UV blocking effect of the Bi@Zn-BiOCl composite material. The benefit of the Bi@Zn-BiOCl composite material is improved stability against natural light irradiation.

[0010] (2) In view of the problem of bismuth oxychloride turning black and gray under light irradiation and the heavy coating of existing inorganic ultraviolet light blocking agents, this invention uses zinc-doped bismuth oxychloride (Zn-BiOCl) as the substrate, introduces impurity defects, and further designs the gain effect of Bi@Zn-BiOCl composite material, thereby improving the stability of Bi@Zn-BiOCl composite material against natural light irradiation discoloration.

[0011] (3) The reaction temperature of this invention is 50~95℃, pH value is 0.80~6.20, and reaction time is 1~6 hours. Compared with the preparation process of similar products, the reaction conditions are mild, the process is short, the energy consumption is low, and the supernatant can be recycled, which is environmentally friendly.

[0012] (4) The Bi@Zn-BiOCl composite material prepared by the present invention has excellent ultraviolet light blocking, photostability and pearly luster. Attached Figure Description

[0013] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technologies in the embodiments of the present invention will be described below with reference to the accompanying drawings.

[0014] Figure 1 The images show the XRD patterns of the Bi@Zn-BiOCl composite materials prepared in Examples 1-3, and the comparative patterns of single-phase BiOCl. Figure 2 SEM image of the Bi@Zn-BiOCl composite material prepared in Example 1; Figure 3 The images show the high-resolution XPS spectra of Zn and Bi elements in the Bi@Zn-BiOCl composite material prepared in Example 1, and the comparative spectra of Bi element in single-phase BiOCl. Figure 4 The color of the Bi@Zn-BiOCl composite material prepared in Example 1 under solar irradiation; Figure 5 The images show the UV-Vis absorption spectra of the Bi@Zn-BiOCl composite materials prepared in Examples 1-4, and the comparative spectra of single-phase BiOCl. Figure 6 The images show the UV-Vis transmittance spectra of the Bi@Zn-BiOCl composite materials prepared in Examples 1-3, and a comparative spectrum of single-phase BiOCl. Detailed Implementation

[0015] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific preferred embodiments, but this is not to limit the scope of protection of the present invention.

[0016] The following specific experimental examples further illustrate the technical solution and effects of the present invention. It should be noted that in the embodiments of the present invention, all reagents, solvents, and materials are commercially available and can be used without further purification.

[0017] Example 1

[0018] (1) Preparation of bismuth nanocrystal precursor: 9 mmol of bismuth oxide was added to 20 mL of 2.5 mol·L⁻¹ bismuth nanocrystal precursor. -1 In a hydrochloric acid solution, the solution was stirred until completely dissolved; then, 0.05 mmol of bismuth powder with an average particle size of 1 μm, 0.5 g of polyvinylpyrrolidone, and 4 mmol of zinc chloride were added sequentially, and the solution was etched at room temperature for 115 min to obtain a suspension A containing bismuth nanocrystals. (2) Coprecipitation and crystal development: Under continuous stirring at 75℃, 18 mmol of sodium chloride was added to 60 mL of deionized water. After complete dissolution, suspension A was slowly added, and NaOH precipitant was added at the same time to keep the pH of the mixture at 2.5. After suspension A was added, the mixture was stirred continuously for 1 hour to crystallize and obtain a white precipitate. (3) Cleaning and drying: The white precipitate is filtered and separated from the liquid, the supernatant is recycled, the white precipitate is washed with deionized water until neutral, and dried at 60°C to obtain the finished Bi@Zn-BiOCl composite material.

[0019] Figure 1 The images show the XRD patterns of the Bi@Zn-BiOCl composite materials prepared in Examples 1-3, and a comparative pattern of single-phase BiOCl. Referring to JCPDS No. 06-0249 for tetragonal fine bismuth oxychloride, the Bi@Zn-BiOCl composite material has an extremely low Bi quantum dot content, and the Bi XRD diffraction peaks are not obvious. The substrate Zn-BiOCl composite material still retains the tetragonal crystal structure of BiOCl.

[0020] Figure 2 The image shows a SEM image of the Bi@Zn-BiOCl composite material prepared in Example 1. The Bi@Zn-BiOCl composite material exhibits a lamellar structure with a lamellar radial dimension of approximately 5~25 μm.

[0021] Figure 3 The images show high-resolution XPS spectra of Zn and Bi elements in the Bi@Zn-BiOCl composite material prepared in Example 1, and a comparative Bi elemental spectrum of single-phase BiOCl. Unlike the Bi elemental spectrum of single-phase bismuth oxychloride, metallic bismuth exists in two forms: elemental Bi quantum dots and Bi in BiOCl. 3+ Ions. In Bi@Zn-BiOCl composites, Zn is doped with BiOCl as +2 valent ions.

[0022] Figure 4 The color of the Bi@Zn-BiOCl composite material prepared in Example 1 under solar irradiation is shown. After 48 hours of irradiation, the Bi@Zn-BiOCl composite material still retains a pearly white luster and shows no obvious blackening or graying.

[0023] Figure 5 The UV-Vis absorption spectra of the Bi@Zn-BiOCl composite materials prepared in Examples 1-4 are shown, along with a comparative spectrum of single-phase BiOCl. Compared to the absorption threshold of 350 nm for single-phase BiOCl, the absorption threshold of the Bi@Zn-BiOCl composite material is broadened to 365-385 nm.

[0024] Figure 6 The ultraviolet-visible transmittance spectra of the Bi@Zn-BiOCl composite materials prepared in Examples 1-3 are shown, along with a comparative spectrum of single-phase BiOCl. Compared with the ultraviolet transmittance of single-phase BiOCl, the ultraviolet transmittance of the Bi@Zn-BiOCl composite material is ≤4%, meaning the ultraviolet light blocking rate is ≥96%.

[0025] Example 2

[0026] (1) Preparation of bismuth nanocrystal precursor: 5 mmol of bismuth oxide was added to 10 mL of 3 mol·L⁻¹ -1 Hydrochloric acid and 0.1 mol·L -1 In a nitric acid mixture, the solution was stirred until completely dissolved. Then, 0.1 mmol of bismuth powder with an average particle size of 0.5 μm, 0.3 g of sodium dodecylbenzenesulfonate, and 6 mmol of zinc chloride were added sequentially. The solution was then etched at room temperature for 140 min to obtain a suspension A containing bismuth nanocrystals. (2) Coprecipitation and crystal development: Under continuous stirring at 80℃, 18 mmol of sodium chloride was added to 50 mL of deionized water. After complete dissolution, suspension A was slowly added, and ammonia precipitant was added at the same time to keep the pH of the mixture at 2.0. After suspension A was added, the mixture was stirred continuously for 2 hours to crystallize and obtain a white precipitate. (3) Cleaning and drying: The white precipitate is filtered and separated from the liquid, the supernatant is recycled, the white precipitate is washed with deionized water until neutral, and dried at 60°C to obtain the Bi@Zn-BiOCl composite material with enhanced UV light blocking rate.

[0027] Example 3

[0028] (1) Preparation of bismuth nanocrystal precursor: 20 mmol of bismuth nitrate pentahydrate was added to 20 mL of 1 mol·L⁻¹ bismuth nanocrystal precursor. -1 Nitric acid and 2 mol·L -1In a mixed solution of hydrochloric acid, the solution was stirred until completely dissolved; then, 0.15 mmol of bismuth powder with an average particle size of 1 μm, 0.2 g of polyethylene glycol, and 8 mmol of zinc chloride were added sequentially, and the solution was etched at room temperature for 120 min to obtain a suspension A containing bismuth nanocrystals. (2) Coprecipitation and crystal development: Under continuous stirring at 80℃, 10 mmol of hydrochloric acid was added to 50 mL of deionized water. After complete dissolution, suspension A was slowly added, and urea precipitant was added at the same time to keep the pH of the mixture at 1.8. After suspension A was added, the mixture was stirred continuously for 4 hours to crystallize and obtain a white precipitate. (3) Cleaning and drying: The white precipitate is filtered and separated from the liquid, the supernatant is recycled, the white precipitate is washed with deionized water until neutral, and dried at 60°C to obtain the Bi@Zn-BiOCl composite material with enhanced UV light blocking rate.

[0029] Example 4

[0030] (1) Preparation of bismuth nanocrystal precursor: 20 mmol of bismuth nitrate pentahydrate was added to 4 mol·L⁻¹ -1 In a mixed solution of hydrochloric acid, the solution was stirred until completely dissolved; then, 0.03 mmol of bismuth powder with an average particle size of 1 μm, 0.2 g of polyethylene glycol, and 8 mmol of zinc chloride were added sequentially, and the solution was etched at room temperature for 140 min to obtain a suspension A containing bismuth nanocrystals. (2) Coprecipitation and crystal development: Under continuous stirring at 90℃, 10 mmol of hydrochloric acid was added to 60 mL of deionized water. After complete dissolution, suspension A was slowly added, and sodium hydroxide precipitant was added at the same time to keep the pH of the mixture at 1.8. After suspension A was added, the mixture was stirred continuously for 4 hours to crystallize and obtain a white precipitate. (3) Cleaning and drying: The white precipitate is filtered and separated from the liquid, the supernatant is recycled, the white precipitate is washed with deionized water until neutral, and dried at 60°C to obtain the Bi@Zn-BiOCl composite material with enhanced UV light blocking rate.

[0031] Example 5

[0032] (1) Preparation of bismuth nanocrystal precursor: 20 mmol of bismuth chloride was added to 3 mol·L⁻¹ -1 In a mixed solution of hydrochloric acid, the solution was stirred until completely dissolved; then, 0.05 mmol of bismuth powder with an average particle size of 1 μm, 0.3 g of polyvinylpyrrolidone, and 6 mmol of zinc chloride were added sequentially, and the solution was etched at room temperature for 120 min to obtain a suspension A containing bismuth nanocrystals. (2) Coprecipitation and crystal development: Under continuous stirring at 90℃, 15 mmol of potassium chloride was added to 50 mL of deionized water. After complete dissolution, suspension A was slowly added, and potassium hydroxide precipitant was added at the same time to keep the pH of the mixture at 2. After suspension A was added, the mixture was stirred continuously for 4 hours to crystallize and obtain a white precipitate. (3) Cleaning and drying: The white precipitate is filtered and separated from the liquid, the supernatant is recycled, the white precipitate is washed with deionized water until neutral, and dried at 60°C to obtain the Bi@Zn-BiOCl composite material with enhanced UV light blocking rate.

[0033] Example 6

[0034] (1) Preparation of bismuth nanocrystal precursor: 20 mmol of bismuth nitrate pentahydrate was added to 2 mol·L⁻¹ -1 In a solution of nitric acid, the solution was stirred until completely dissolved; then, 0.05 mmol of bismuth powder with an average particle size of 0.2 μm, 0.2 g of polyvinylpyrrolidone, and 8 mmol of zinc chloride were added sequentially, and the solution was etched at room temperature for 120 min to obtain a suspension A containing bismuth nanocrystals. (2) Coprecipitation and crystal development: Under continuous stirring at 90℃, 20 mmol of hydrochloric acid was added to 60 mL of deionized water. After complete dissolution, suspension A was slowly added, and sodium hydroxide precipitant was added at the same time to keep the pH of the mixture at 1.8. After suspension A was added, the mixture was stirred continuously for 2 hours to crystallize and obtain a white precipitate. (3) Cleaning and drying: The white precipitate is filtered and separated from the liquid, the supernatant is recycled, the white precipitate is washed with deionized water until neutral, and dried at 60°C to obtain the Bi@Zn-BiOCl composite material with enhanced UV light blocking rate.

[0035] The brightness of the Bi@Zn-BiOCl composite materials prepared in Examples 1-6 of Table 1 ranges from 4.5 to 15.3.

[0036] Table 1. Gloss of Bi@Zn-BiOCl composite materials prepared in Examples 1-6

[0037] Compared with a commercially available bismuth oxychloride pearlescent pigment, Example 1 showed a significantly improved UV light blocking rate, a significantly broadened absorption threshold, and a significantly improved tolerance to light irradiation-induced color change.

[0038] Compared with a certain imported heavily coated bismuth oxychloride pearlescent pigment, Example 3 shows a significantly improved UV light blocking rate and a significantly broadened absorption threshold.

[0039] The preferred embodiments described above are merely illustrative examples to clearly illustrate the invention and are not intended to limit the implementation of the invention. Those skilled in the art can make various variations and modifications to the technical solutions of the invention based on the above description and the methods and techniques described above. However, any simple modifications, equivalent substitutions, and improvements made within the spirit and principles of the invention should be included within the scope of protection of the invention.

Claims

1. A bismuth oxychloride-based composite material (i.e., Bi@Zn-BiOCl composite material), characterized in that, The composite material is composed of metallic bismuth nanocrystals and bismuth oxychloride matrix, and its ultraviolet light blocking rate is ≥95%. Furthermore, the Bi@Zn-BiOCl composite material has a broadened ultraviolet light absorption threshold to 365~385 nm, a brightness of 4.5~15.3, and a stable duration of resistance to natural light irradiation color change ≥32 h.

2. The method for preparing the bismuth oxychloride-based composite material according to claim 1, characterized in that, Includes the following steps: S01. Preparation of precursor of metallic bismuth nanocrystals: A bismuth-containing compound was added to an acidic solution and stirred until completely dissolved. Then, bismuth powder, surfactant and zinc salt were added in sequence and etched at room temperature to obtain a suspension A containing bismuth nanocrystals. S02. Coprecipitation and crystal development: Under continuous stirring at a certain temperature, a chlorine source is added to deionized water and completely dissolved. Then, suspension A is slowly added, along with a precipitant, to maintain the pH of the mixture within a certain range. After suspension A is added, the mixture is stirred continuously for a certain time to crystallize, and finally, a white precipitate is obtained. S03. Cleaning and drying: The white precipitate is filtered and separated from the liquid, the supernatant is recycled, the white precipitate is washed with deionized water until neutral, and dried to obtain the finished bismuth oxychloride-based composite material; Furthermore, in step S01, the acidic solution is selected from any one or both of hydrochloric acid and nitric acid; even further, the concentration of the hydrochloric acid solution is 1.50~5.00 mol·L⁻¹. -1 Furthermore, the concentration of the nitric acid solution is 0.05~1.00 mol·L⁻¹. -1 .

3. The method for preparing the bismuth oxychloride-based composite material according to claim 2, characterized in that, In step S01, the bismuth powder has a particle size of 0.1~5 μm.

4. The method for preparing the bismuth oxychloride-based composite material according to claim 2, characterized in that, In step S01, the bismuth-containing compound is selected from any one or more of bismuth oxide, bismuth nitrate pentahydrate, bismuth nitrate, and bismuth chloride.

5. The method for preparing the bismuth oxychloride-based composite material according to claim 2, characterized in that, In step S01, the zinc salt is selected from any one or more of zinc chloride, zinc sulfate, and zinc oxide.

6. The method for preparing the bismuth oxychloride-based composite material according to claim 2, characterized in that, In step S01, the surfactant is selected from any one or more of sodium dodecylbenzenesulfonate, polyethylene glycol, polyvinylpyrrolidone, and citric acid.

7. The method for preparing the bismuth oxychloride-based composite material according to claim 2, characterized in that, In step S01, the corrosion time is 60 to 140 minutes.

8. The method for preparing the bismuth oxychloride-based composite material according to claim 2, characterized in that, In step S01, the ratio of bismuth-containing compound: acidic solution: bismuth powder: surfactant: zinc salt is 3~20 mmol: 10~20 mL: 0.01~0.2 mmol: 0.1~0.5 g: 1~10 mmol.

9. The method for preparing the bismuth oxychloride-based composite material according to claim 2, characterized in that, Furthermore, in step S02, the temperature for co-precipitation and crystal development is 50~95℃; Furthermore, in step S02, the chlorine source is selected from any one or more of hydrochloric acid, sodium chloride, and potassium chloride; Furthermore, in step S02, the precipitant is selected from any one or more of ammonia, sodium hydroxide, potassium hydroxide, urea, and ammonium chloride; Furthermore, in step S02, the pH value is maintained within the range of 0.80 to 6.20; Furthermore, in step S02, the crystallization heat preservation time is 1 to 6 hours; In step S02, the ratio of deionized water: suspension A: chlorine source is 40~120 mL: 20 mL: 7.5~20 mmol.

10. Use of the Bi@Zn-BiOCl composite material of claim 1 in the preparation of ultraviolet light blocking agents or ultraviolet light blocking pigments.

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