Titanium-free silver white pearlescent pigment, and preparation method therefor and use thereof

Abstract

Disclosed are a titanium-free silver white pearlescent pigment, and a preparation method therefor and a use thereof. The pearlescent pigment of the present invention has an obvious pearlescent effect, variable particle sizes, and glossiness from soft to high gloss, can be widely applied to multiple fields, particularly the fields of cosmetics and personal care products, and has good practical value. The pearlescent pigment does not contain titanium, has excellent ultraviolet resistance, and overcomes the problems of color change and color migration of a conventional titanium-containing pearlescent pigment in the production and application of cosmetics. In addition, the pearlescent pigment further has the advantages of simple preparation process, easily available raw materials, convenience in processing and operation and the like, and can be applied to large-scale production.

Description

Titanium-free silver-white pearlescent pigment, preparation method and use thereof Technical Field

[0001] The invention relates to a pearlescent pigment, in particular to a titanium-free silver-white pearlescent pigment and a preparation method and application thereof, belonging to the technical field of pearlescent pigment production. Background Art

[0002] Pearlescent pigments, with their unique optical properties and color effects, have been widely used in coatings, plastics, ceramics, leather, cosmetics, decorative materials, and other fields. In recent years, they have particularly shined in cosmetics and personal care products such as lip gloss, eye shadow, pressed powder, nail polish, moisturizer, face cream, shampoo, and conditioner. Their primary function is to maintain healthy skin by beautifying, cleansing, or protecting it from dryness and UV damage, thereby protecting it from dryness and UV rays.

[0003] Currently, pearlescent pigments marketed by domestic and international manufacturers typically feature a layered sandwich structure consisting of two or more metal oxides coated on a substrate surface. Examples include substrate flakes / TiO2, substrate flakes / SnO2 / TiO2, substrate flakes / Fe2O3, substrate flakes / SnO2 / TiO2 / Fe2O3, pearlescent pigment / organic pigment, and other derivatives thereof. These are typically mica titanium, mica iron, or mica titanium / iron pearlescent pigments and their derivatives, typically coated with TiO2, Fe2O3, or TiO2 / Fe2O3. While nano-TiO2 in pearlescent pigments exhibits strong photocatalytic properties, high polarity, and strong hydrophilicity, along with poor visible light transmittance, it exhibits excellent UV shielding capabilities. However, its use in cosmetics and personal care products can lead to color shift and color transfer, limiting its application in these areas.

[0004] Moreover, on February 18, 2020, the European Union issued Commission Delegated Regulation (EU) 2020 / 217 (COMMISSION DELEGATED REGULATION (EU) 2020 / 217 of 4 October 2019), which listed TiO2 as a Category II carcinogen and required that "solid mixtures containing 1% or more TiO2 be labeled accordingly on their packaging." This regulation came into effect on September 9, 2021. On January 14, 2022, the European Union issued Commission Regulation (EU) 2022 / 63 prohibiting the use of TiO2 (E171) as a food additive, which restricts the application of TiO2 in the pharmaceutical and food sectors. In June 2022, the European Commission for Health and Food Safety sought opinions on the safety of TiO2 in cosmetics. The main content included that since it is classified as a Category 2 carcinogen only by inhalation, the Scientific Committee on Consumer Safety (SCCS) re-evaluated TiO2. The focus is on genotoxicity and exposure through inhalation and oral routes (lip care, lipstick, toothpaste, loose powder, hair spray), as well as seeking opinions on whether TiO2 is safe for use in oral cosmetics, which will further restrict its use in cosmetics.

[0005] In summary, how to realize TiO2-free pearlescent pigments as cosmetic raw materials and meet the requirements of relevant regulations has become a technical problem that needs to be solved urgently.

[0006] Summary of the Invention

[0007] In view of the fact that titanium-containing pearlescent pigments in the prior art suffer from color change and color migration when used in cosmetics and personal care products and fail to meet the strict requirements of relevant regulations, the present invention provides a titanium-free silver-white pearlescent pigment and its preparation method and use. The pearlescent pigment of the present invention does not contain titanium and has excellent ultraviolet resistance, thus overcoming the color change and color migration problems of conventional titanium-containing pearlescent pigments in the production and application of cosmetics.

[0008] To achieve the above technical objectives, the first embodiment of the present invention provides a titanium-free silver-white pearlescent pigment:

[0009] A titanium-free silver-white pearlescent pigment comprises a substrate, a magnesium oxide layer coated and deposited on the surface of the substrate, a high-refractive index layer coated and deposited on the surface of the magnesium oxide layer, and a protective layer coated and deposited on the surface of the high-refractive index layer.

[0010] Preferably, the substrate is one of mica, glass flakes, SiO2 flakes, Al2O3 flakes and bismuth oxychloride flakes, preferably one of mica flakes, glass flakes, SiO2 flakes, Al2O3 flakes and bismuth oxychloride flakes, more preferably natural mica powder or synthetic mica powder or glass flake powder.

[0011] Preferably, the high refractive index layer is a metal oxide layer with a refractive index greater than 1.8, and the metal oxide is preferably one of ZrO2, CeO2, and ZnO, and the metal oxide is more preferably CeO2 and / or ZnO.

[0012] Preferably, the protective layer is one or more of SiO2, Al2O3, and a silane compound, preferably SiO2 and / or Al2O3, more preferably SiO2. Preferably, the silane compound is one or more selected from (3-glycidoxypropyl)trimethoxysilane, (3-aminopropyl)triethoxysilane, methacrylpropylmethoxysilane, 3-(2-aminoethylamino)propyltrimethoxysilane, methyltriethoxysilane, and n-hexyltrimethoxysilane.

[0013] Preferably, the coverage of the magnesium oxide layer is 0.2-6%, preferably 0.5-5%, more preferably 1-4%, and further preferably 1.2-2.5%, for example, one of 0.2%, 0.3%, 0.5%, 0.8%, 1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 2%, 2.2%, 2.4%, 2.5%, 2.7%, 3%, 3.2%, 3.4%, 3.6%, 3.8%, 4%, 4.2%, 4.5%, 5%, 5.5%, and 6%.

[0014] Preferably, the coverage of the high refractive index layer is 10-45%, preferably 15-40%, more preferably 20-35%, for example, one of 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 34%, 36%, 38%, 40%, 42%, and 45%.

[0015] Preferably, the coverage of the protective layer is 0.05-7%, preferably 0.1-6%, more preferably 0.3-5%, for example, one of 0.05%, 0.08%, 0.1%, 0.12%, 0.15%, 0.18%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 2%, 2.2%, 2.4%, 2.6%, 2.8%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, and 7%.

[0016] Preferably, the thickness of the substrate is 50-500 nm, preferably 75-450 nm, more preferably 100-400 nm.

[0017] Preferably, the particle size of the substrate is ≤500 μm, preferably ≤300 μm, and more preferably ≤250 μm.

[0018] According to a second embodiment of the present invention, a method for preparing a titanium-free silver-white pearlescent pigment is provided:

[0019] A method for preparing a titanium-free silver-white pearlescent pigment or a method for preparing a titanium-free silver-white pearlescent pigment as described in the first embodiment, the preparation method comprising:

[0020] 1) dispersing the substrate in a dispersion to obtain a first suspension;

[0021] 2) adding a soluble magnesium salt solution to the first suspension to obtain a second suspension;

[0022] 3) adding a soluble metal salt solution to the second suspension to obtain a third suspension;

[0023] 4) adding a soluble protective salt solution to the third suspension to obtain a fourth suspension;

[0024] 5) The fourth suspension is filtered, washed, dried, calcined, and sieved in sequence to obtain a titanium-free silver-white pearlescent pigment.

[0025] Preferably, the dispersion liquid is deionized water, and the liquid-to-solid mass ratio of the dispersion liquid to the added amount of the substrate is 3-20:1, preferably 5-15:1, and more preferably 7-12:1.

[0026] Preferably, the soluble magnesium salt is one or more of magnesium nitrate, magnesium sulfate, and magnesium chloride. The concentration of the soluble magnesium salt solution is 25-600 g / L, preferably 50-300 g / L, and more preferably 80-200 g / L. The amount of the soluble magnesium salt solution added is such that the coverage of the soluble magnesium salt on the substrate surface in the second suspension is 0.5-15%, preferably 0.8-12%, and more preferably 1-10%.

[0027] Preferably, the soluble metal salt is one or more of cerium nitrate, cerium chloride, cerium sulfate, zinc nitrate, zinc sulfate, and zinc chloride, preferably a mixed salt consisting of one or more of cerium nitrate, cerium chloride, and cerium sulfate and one or more of zinc nitrate, zinc sulfate, and zinc chloride, more preferably a mixed salt consisting of cerium nitrate and zinc chloride.

[0028] Preferably, the concentration of the soluble metal salt solution is 80-700 g / L, preferably 100-500 g / L, more preferably 120-300 g / L.

[0029] Preferably, the amount of the soluble metal salt solution added is such that the coverage rate of the soluble metal salt in the third suspension is 25-88%, preferably 30-80%, more preferably 35-75%.

[0030] Preferably, the soluble protective salt is one or more of aluminum chloride, aluminum nitrate, aluminum sulfate, sodium metasilicate pentahydrate, sodium metasilicate nonahydrate, and silane compounds, preferably aluminum chloride and / or sodium metasilicate pentahydrate, more preferably sodium metasilicate pentahydrate.

[0031] Preferably, the concentration of the soluble protective salt solution is 30-250 g / L, preferably 40-200 g / L, more preferably 50-180 g / L.

[0032] Preferably, the amount of the soluble protective salt solution added is such that the coverage rate of the soluble protective salt in the fourth suspension is 0.1-20%, preferably 0.5-15%, more preferably 0.8-10%.

[0033] Preferably, step 1) is specifically as follows: dispersing the substrate in the dispersion in proportion, stirring and mixing thoroughly, heating to 50-90° C. (preferably 75-85° C.) and maintaining a constant temperature, and using an acid or base (for example, a hydrochloric acid solution with a mass concentration of 5-18% or a sodium hydroxide solution with a mass concentration of 5-15%) to adjust the pH of the system to 7-9 (preferably 7.5-8.5) to obtain a first suspension.

[0034] Preferably, step 2) is specifically as follows: adding a soluble magnesium salt solution to the first suspension in proportion, controlling the temperature to 65-90° C. (preferably 75-85° C.), and using an acid or base (e.g., a hydrochloric acid solution with a mass concentration of 5-18% or a sodium hydroxide solution with a mass concentration of 5-15%) to adjust the pH of the system to 7-9 (preferably 7.5-8.5) to obtain a second suspension. And / or

[0035] Preferably, step 3) is specifically as follows: adding a soluble metal salt solution to the second suspension in proportion, controlling the temperature to 65-90° C. (preferably 75-85° C.), and using an acid or base (e.g., a hydrochloric acid solution with a mass concentration of 5-18% or a sodium hydroxide solution with a mass concentration of 5-15%) to adjust the pH of the system to 5-9 (preferably 5.5-8.5) to obtain a third suspension. And / or

[0036] Preferably, step 4) is specifically as follows: adding a soluble protective salt solution to the third suspension in proportion, controlling the temperature to 65-90° C. (preferably 75-85° C.), and using an acid or base (for example, a hydrochloric acid solution with a mass concentration of 5-18% or a sodium hydroxide solution with a mass concentration of 5-15%) to adjust the pH of the system to 7-10 (preferably 7.5-9) to obtain a fourth suspension.

[0037] Preferably, step 5) is specifically: filtering and washing the fourth suspension, and then drying it in an oven at 80-150° C. (preferably 100-135° C.); after drying, calcining it at 700-900° C. (preferably 750-850° C.) for 1-15 min (preferably 2-10 min) and sieving it to obtain a titanium-free silver white pearlescent pigment.

[0038] According to a third embodiment of the present invention, there is provided a use of a titanium-free silver white pearlescent pigment:

[0039] A use of a titanium-free silver-white pearlescent pigment, or a use of the titanium-free silver-white pearlescent pigment as described in the first embodiment, or a use of a titanium-free silver-white pearlescent pigment prepared by the method described in the second embodiment, wherein the titanium-free silver-white pearlescent pigment is used to prepare one or more of coatings, inks, plastics, and cosmetics. Preferably, the titanium-free silver-white pearlescent pigment is used to prepare one or more of lip gloss, eye shadow, pressed powder, nail polish, lotion, face cream, shampoo, cleansing cream, and handmade soap.

[0040] In the present invention, the titanium-free silver-white pearlescent pigment does not contain titanium. By sequentially coating and depositing an MgO layer, a metal oxide layer (e.g., a CeO2 layer, a ZnO layer, a ZnO / CeO2 layer\CeO2-ZnO composite layer), and an outermost protective layer (e.g., a SiO2 layer, an Al2O3 layer) on the surface of a substrate, a silver-white pearlescent pigment with excellent performance and good gloss is prepared. The preparation method is simple, and no titanium tetrachloride is added during the preparation process, and there is no TiO2 component. This can overcome the adverse effects of free radicals generated by TiO2 photocatalysis in mica titanium pearlescent pigments on the pearlescent pigment itself and the coating / resin system in the application field, such as reduced pearlescent effect, discoloration, powdering, flaking, and other problems.

[0041] In the present invention, an MgO layer is added between the metal oxide layer and the substrate, and the MgO layer is used to inhibit the precipitation of oxygen vacancies in the metal oxide layer (such as the CeO2 layer), thereby inhibiting the oxidation catalytic activity of the metal oxide, thereby improving the application of the titanium-free silver-white pearlescent pigment in various anti-ultraviolet fields such as anti-aging and cosmetics. The metal oxide is a cerium salt or zinc salt that is hydrolyzed and calcined to generate CeO2 and / or ZnO, which is an important precipitant for the manufacture of mica pearlescent pigments. Compared with the TiO2 component in the mica titanium pearlescent pigment, the CeO2 component in the titanium-free silver-white pearlescent pigment of the present invention has the following advantages: First, the refractive index of CeO2 is n=2.2, which is lower than that of TiO2 (gold red TiO2n=2.72; anatase TiO2n=2.5), and has better transmittance to visible light. In addition, its own color is soft and not as white as TiO2, so it is used in cosmetics. First, CeO2 can make skin whiter, without creating a "pale" effect, and its powdery texture is smoother, giving it a better skin feel. Second, CeO2 has a unique rare earth 4f electron layer structure, rich in electron transition energy levels, and is sensitive to light absorption. Its absorption band is mostly in the ultraviolet region below 400nm, and the absorbed ultraviolet light is mainly used for electron energy level transitions, reducing photocatalysis. Its photocatalytic performance is far lower than that of TiO2. In addition, the small size effect, high specific surface area effect, and macroscopic quantum effect of nanoparticles give it strong scattering and reflection effects on ultraviolet light. Therefore, CeO2 has the dual function of absorbing and reflecting ultraviolet light, and its ultraviolet shielding efficiency is relatively high.

[0042] In the present invention, the outermost SiO2 and / or Al2O3 protective layer is a silicate or aluminum salt which is hydrolyzed and calcined to generate SiO 2、 Al2O3, this layer can cover the original optically active points of the pearlescent pigment, partially isolating the metal oxide layer from the effects of light, free H2O, and O2; secondly, when the metal oxide layer is irradiated by light passing through the protective layer, the excited electrons pass through the defective lattices of SiO2 and Al2O3, and the SiO2 and Al2O3 layers absorb the excited electrons and recombine with the holes, thereby reducing or blocking the number of electrons and holes reaching the surface of the metal oxide layer and improving the light resistance of the pearlescent pigment.

[0043] In the present invention, the coating thickness of the MgO layer is generally not more than 30nm (6-15nm). If the coating thickness of the MgO layer is too thin or the coating rate is too low (for example, less than 0.2%), it cannot effectively inhibit the oxidation catalytic activity of the metal oxide, affecting its anti-aging and anti-ultraviolet properties. If the coating thickness of the MgO layer is too thick or the coating rate is too high (for example, higher than 6%), it will occupy the thickness of the cerium oxide layer, which will weaken the pearlescent effect of the pearlescent pigment on the one hand, and also affect the ultraviolet shielding ability of the pearlescent pigment (the coating thickness is strongly correlated with the pearlescent effect of the pearlescent pigment. The thicker the thickness, the greater the deviation in hue, brightness and covering).

[0044] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0045] 1: The titanium-free silver-white pearlescent pigment of the present invention has excellent UV resistance, overcoming the color change and color migration problems of conventional mica titanium in the production and application of cosmetics. In addition, its structural components do not contain TiO2, which can circumvent a series of issues arising from future relevant regulations on the safety of TiO2 or materials containing TiO2 components in cosmetics or personal care products.

[0046] 2: The titanium-free silver-white pearlescent pigment provided by the present invention has obvious pearlescent effect, rich particle size, and brightness ranging from soft to shiny. It can be widely used in many fields, especially in the fields of cosmetics and personal care products, and has good practical value.

[0047] 3: The titanium-free silver-white pearlescent pigment provided by the present invention has the advantages of simple preparation process, readily available raw materials, convenient processing and operation, and can be applied to large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] FIG1 is an electron microscope image (100 μm) of the pearlescent pigment obtained in Example 1 of the present invention.

[0049] FIG2 is an electron microscope image (20 μm) of the pearlescent pigment obtained in Example 1 of the present invention.

[0050] FIG3 is a screenshot of the SGS heavy metal test data report of the pearlescent pigment obtained in Example 1 of the present invention. DETAILED DESCRIPTION

[0051] The technical solutions of the present invention are illustrated below with examples, and the scope of protection requested by the present invention includes but is not limited to the following embodiments.

[0052] Example 1

[0053] 100 g of synthetic mica powder with a particle size range of 10-60 μm was placed in a 2 L reactor, deionized water was added at a solid-liquid mass ratio of 1:10, and the mixture was stirred to form a suspension. The suspension was heated in a constant temperature water bath and stabilized at 80° C. The pH of the suspension was adjusted to 7.5 with 15% dilute hydrochloric acid to obtain a first suspension.

[0054] A magnesium chloride solution with a concentration of 135 g / L was added to the first suspension using a peristaltic pump, and a sodium hydroxide solution with a mass concentration of 5% was used to maintain a constant pH value. When the magnesium chloride coating rate reached 3%, the addition was stopped and stirring was continued for 20 minutes to obtain a second suspension.

[0055] The temperature of the second suspension was maintained and stably controlled at 80° C., and then a 95 g / L cerium nitrate solution was added. At the same time, a 5% by mass sodium hydroxide solution was used to balance the pH value to 8.0. When the coverage rate of the cerium nitrate reached 53%, the addition was stopped and stirring was continued for 20 minutes to obtain a third suspension.

[0056] The temperature of the third suspension was maintained and stably controlled at 80° C., and then a 100 g / L sodium metasilicate pentahydrate solution was added. At the same time, a 5% mass concentration of hydrochloric acid solution was used to balance the pH value to 8.0. When the coverage rate of sodium metasilicate pentahydrate reached 3.5%, the addition was stopped and stirring was continued for 20 minutes to obtain a fourth suspension.

[0057] The fourth suspension was vacuum filtered, the filter cake was washed with deionized water, and the filter cake was dried in an oven at 120°C; the dried filter cake powder was then placed in a muffle furnace, gradually heated to 800°C and calcined, and kept warm for 10 minutes. After the insulation was completed, the powder sample was taken out and naturally cooled to room temperature, then washed and dried to obtain a pearlescent pigment with a silvery white appearance (the coverage rates of the magnesium oxide layer, the high refractive index layer, and the protective layer on the substrate surface were detected to be approximately 1.24%, 27.51%, and 0.97%, respectively).

[0058] Example 2

[0059] 100 g of natural mica powder with a particle size range of 10-70 μm was placed in a 2 L reactor, deionized water was added at a solid-liquid mass ratio of 1:10, and the mixture was stirred to form a suspension. The suspension was heated in a constant temperature water bath and stabilized at 80° C. The pH of the suspension was adjusted to 7.5 using 15% dilute hydrochloric acid to obtain a first suspension.

[0060] A magnesium chloride solution with a concentration of 140 g / L was added to the first suspension using a peristaltic pump, and a sodium hydroxide solution with a mass concentration of 5% was used to maintain a constant pH value. When the magnesium chloride coverage reached 3.5%, the addition was stopped and stirring was continued for 20 minutes to obtain a second suspension.

[0061] The temperature of the second suspension was maintained and stably controlled at 80° C., and then a 100 g / L cerium nitrate solution was added. At the same time, a 5% by mass sodium hydroxide solution was used to balance the pH value to 8.0. When the coverage rate of the cerium nitrate reached 55%, the addition was stopped and stirring was continued for 20 minutes to obtain a third suspension.

[0062] The temperature of the third suspension was maintained and stably controlled at 80° C., and then a 100 g / L sodium metasilicate pentahydrate solution was added. At the same time, a 5% mass concentration of hydrochloric acid solution was used to balance the pH value to 8.0. When the coverage rate of sodium metasilicate pentahydrate reached 3.5%, the addition was stopped and stirring was continued for 20 minutes to obtain a fourth suspension.

[0063] The fourth suspension was vacuum filtered, the filter cake was washed with deionized water, and the filter cake was dried in an oven at 120°C; the dried filter cake powder was then placed in a muffle furnace, gradually heated to 850°C and calcined, and kept warm for 10 minutes. After the insulation was completed, the powder sample was taken out and naturally cooled to room temperature, and then washed and dried to obtain a pearlescent pigment with a silvery white appearance (the coverage rates of the magnesium oxide layer, the high refractive index layer, and the protective layer on the substrate surface were detected to be approximately 3.43%, 28.44%, and 0.94%, respectively).

[0064] Example 3

[0065] 100 g of glass flakes with a particle size range of 25-100 μm were placed in a 2 L reactor, deionized water was added at a solid-liquid mass ratio of 1:10, and the mixture was stirred to form a suspension. The suspension was heated in a constant temperature water bath and stabilized at 80° C. The pH of the suspension was adjusted to 7.5 using 15% dilute hydrochloric acid to obtain a first suspension.

[0066] A magnesium chloride solution with a concentration of 135 g / L was added to the first suspension using a peristaltic pump, and a sodium hydroxide solution with a mass concentration of 5% was used to maintain a constant pH value. When the magnesium chloride coating rate reached 3%, the addition was stopped and stirring was continued for 20 minutes to obtain a second suspension.

[0067] The temperature of the second suspension was maintained and stably controlled at 80° C., and then a 95 g / L cerium nitrate solution was added. At the same time, a 5% by mass sodium hydroxide solution was used to balance the pH value to 8.0. When the coverage rate of the cerium nitrate reached 30%, the addition was stopped and stirring was continued for 20 minutes to obtain a third suspension.

[0068] The temperature of the third suspension was maintained and stably controlled at 80° C., and then a 100 g / L sodium metasilicate pentahydrate solution was added. At the same time, a 5% mass concentration of hydrochloric acid solution was used to balance the pH value to 8.0. When the coverage rate of sodium metasilicate pentahydrate reached 4.0%, the addition was stopped and stirring was continued for 20 minutes to obtain a fourth suspension.

[0069] The fourth suspension was vacuum filtered, the filter cake was washed with deionized water, and the filter cake was dried in an oven at 120°C; the dried filter cake powder was then placed in a muffle furnace, gradually heated to 800°C and calcined, and kept warm for 10 minutes. After the insulation was completed, the powder sample was taken out and naturally cooled to room temperature, then washed and dried to obtain a pearlescent pigment with a silvery white appearance (the coverage rates of the magnesium oxide layer, the high refractive index layer, and the protective layer on the substrate surface were detected to be approximately 1.21%, 13.37%, and 1.11%, respectively).

[0070] Example 4

[0071] 100 g of synthetic mica powder with a particle size range of 10-60 μm was placed in a 2 L reactor, deionized water was added at a solid-liquid mass ratio of 1:10, and the mixture was stirred to form a suspension. The suspension was heated in a constant temperature water bath and stabilized at 80° C. The pH of the suspension was adjusted to 7.5 with 15% dilute hydrochloric acid to obtain a first suspension.

[0072] A magnesium chloride solution with a concentration of 135 g / L was added to the first suspension using a peristaltic pump, and a sodium hydroxide solution with a mass concentration of 5% was used to maintain a constant pH value. When the magnesium chloride coating rate reached 3%, the addition was stopped and stirring was continued for 20 minutes to obtain a second suspension.

[0073] The temperature of the second suspension was maintained and stably controlled at 80° C., and then a 95 g / L cerium nitrate solution was added. At the same time, a 5% by mass sodium hydroxide solution was used to balance the pH to 8.0. When the coverage rate of the cerium nitrate reached 40%, the addition was stopped, and stirring was continued for 20 minutes. Then, a 75 g / L zinc chloride solution was added, and the equilibrium pH was adjusted to 6.5 with 10% dilute hydrochloric acid. When the coverage rate of the zinc chloride reached 11%, the addition was stopped, and stirring was continued for 20 minutes to obtain a third suspension.

[0074] The temperature of the third suspension was maintained and stably controlled at 80° C., and then a 100 g / L sodium metasilicate pentahydrate solution was added. At the same time, a 5% mass concentration of hydrochloric acid solution was used to balance the pH value to 8.0. When the coverage rate of sodium metasilicate pentahydrate reached 3.5%, the addition was stopped and stirring was continued for 20 minutes to obtain a fourth suspension.

[0075] The fourth suspension was vacuum filtered, the filter cake was washed with deionized water, and the filter cake was dried in an oven at 120°C; the dried filter cake powder was then placed in a muffle furnace, gradually heated to 800°C and calcined, and kept warm for 10 minutes. After the insulation was completed, the powder sample was taken out and naturally cooled to room temperature, then washed and dried to obtain a pearlescent pigment with a silvery white appearance (the coverage rates of the magnesium oxide layer, the high refractive index layer, and the protective layer on the substrate surface were detected to be approximately 1.22%, 27.60%, and 0.98%, respectively).

[0076] Example 5

[0077] 100 g of synthetic mica powder with a particle size range of 10-60 μm was placed in a 2 L reactor, deionized water was added at a solid-liquid mass ratio of 1:10, and the mixture was stirred to form a suspension. The suspension was heated in a constant temperature water bath and stabilized at 80° C. The pH of the suspension was adjusted to 7.5 with 15% dilute hydrochloric acid to obtain a first suspension.

[0078] A magnesium chloride solution with a concentration of 135 g / L was added to the first suspension using a peristaltic pump, and a sodium hydroxide solution with a mass concentration of 5% was used to maintain a constant pH value. When the magnesium chloride coating rate reached 3%, the addition was stopped and stirring was continued for 20 minutes to obtain a second suspension.

[0079] The temperature of the second suspension was maintained and stably controlled at 80° C., and then a mixed solution of cerium nitrate with a concentration of 95 g / L and zinc chloride with a concentration of 75 g / L was added. At the same time, a sodium hydroxide solution with a mass concentration of 5% was used to balance the pH value to 8.0. When the total coverage rate of cerium nitrate-zinc chloride reached 51%, the addition was stopped and stirring was continued for 20 minutes to obtain a third suspension.

[0080] The temperature of the third suspension was maintained and stably controlled at 80° C., and then a 100 g / L sodium metasilicate pentahydrate solution was added. At the same time, a 5% mass concentration of hydrochloric acid solution was used to balance the pH value to 8.0. When the coverage rate of sodium metasilicate pentahydrate reached 3.5%, the addition was stopped and stirring was continued for 20 minutes to obtain a fourth suspension.

[0081] The fourth suspension was vacuum filtered, the filter cake was washed with deionized water, and the filter cake was dried in an oven at 120°C; the dried filter cake powder was then placed in a muffle furnace, gradually heated to 800°C and calcined, and kept warm for 10 minutes. After the insulation was completed, the powder sample was taken out and naturally cooled to room temperature, then washed and dried to obtain a pearlescent pigment with a silvery white appearance (the coverage rates of the magnesium oxide layer, the high refractive index layer, and the protective layer on the substrate surface were detected to be approximately 1.26%, 27.55%, and 0.96%, respectively).

[0082] Example 6

[0083] 100 g of synthetic mica powder with a particle size range of 10-60 μm was placed in a 2 L reactor, deionized water was added at a solid-liquid mass ratio of 1:10, and the mixture was stirred to form a suspension. The suspension was heated in a constant temperature water bath and stabilized at 80° C. The pH of the suspension was adjusted to 7.5 with 15% dilute hydrochloric acid to obtain a first suspension.

[0084] A magnesium chloride solution with a concentration of 135 g / L was added to the first suspension using a peristaltic pump, and a sodium hydroxide solution with a mass concentration of 5% was used to maintain a constant pH value. When the magnesium chloride coverage rate reached 5%, the addition was stopped and stirring was continued for 20 minutes to obtain a second suspension.

[0085] The temperature of the second suspension was maintained and stably controlled at 80° C., and then a 95 g / L cerium nitrate solution was added. At the same time, a 5% by mass sodium hydroxide solution was used to balance the pH value to 8.0. When the coverage rate of the cerium nitrate reached 53%, the addition was stopped and stirring was continued for 20 minutes to obtain a third suspension.

[0086] The temperature of the third suspension was maintained and stably controlled at 80° C., and then a 100 g / L sodium metasilicate pentahydrate solution was added. At the same time, a 5% mass concentration of hydrochloric acid solution was used to balance the pH value to 8.0. When the coverage rate of sodium metasilicate pentahydrate reached 3.5%, the addition was stopped and stirring was continued for 20 minutes to obtain a fourth suspension.

[0087] The fourth suspension was vacuum filtered, the filter cake was washed with deionized water, and the filter cake was dried in an oven at 120°C; the dried filter cake powder was then placed in a muffle furnace, gradually heated to 800°C and calcined, and kept warm for 10 minutes. After the insulation was completed, the powder sample was taken out and naturally cooled to room temperature, then washed and dried to obtain a pearlescent pigment with a silvery white appearance (the coverage rates of the magnesium oxide layer, the high refractive index layer, and the protective layer on the substrate surface were detected to be approximately 2.05%, 27.49%, and 0.98%, respectively).

[0088] Example 7

[0089] 100 g of synthetic mica powder with a particle size range of 10-60 μm was placed in a 2 L reactor, deionized water was added at a solid-liquid mass ratio of 1:10, and the mixture was stirred to form a suspension. The suspension was heated in a constant temperature water bath and stabilized at 80° C. The pH of the suspension was adjusted to 7.5 with 15% dilute hydrochloric acid to obtain a first suspension.

[0090] A magnesium chloride solution with a concentration of 135 g / L was added to the first suspension using a peristaltic pump, and a sodium hydroxide solution with a mass concentration of 5% was used to maintain a constant pH value. When the magnesium chloride coverage rate reached 6%, the addition was stopped and stirring was continued for 20 minutes to obtain a second suspension.

[0091] The temperature of the second suspension was maintained and stably controlled at 80° C., and then a 95 g / L cerium nitrate solution was added. At the same time, a 5% by mass sodium hydroxide solution was used to balance the pH value to 8.0. When the coverage rate of the cerium nitrate reached 53%, the addition was stopped and stirring was continued for 20 minutes to obtain a third suspension.

[0092] The temperature of the third suspension was maintained and stably controlled at 80° C., and then a 100 g / L sodium metasilicate pentahydrate solution was added. At the same time, a 5% mass concentration of hydrochloric acid solution was used to balance the pH value to 8.0. When the coverage rate of sodium metasilicate pentahydrate reached 3.5%, the addition was stopped and stirring was continued for 20 minutes to obtain a fourth suspension.

[0093] The fourth suspension was vacuum filtered, the filter cake was washed with deionized water, and the filter cake was dried in an oven at 120°C; the dried filter cake powder was then placed in a muffle furnace, gradually heated to 800°C and calcined, and kept warm for 10 minutes. After the insulation was completed, the powder sample was taken out and naturally cooled to room temperature, then washed and dried to obtain a pearlescent pigment with a silvery white appearance (the coverage rates of the magnesium oxide layer, the high refractive index layer, and the protective layer on the substrate surface were detected to be approximately 2.46%, 27.50%, and 0.99%, respectively).

[0094] Example 8

[0095] 100 g of synthetic mica powder with a particle size range of 10-60 μm was placed in a 2 L reactor, deionized water was added at a solid-liquid mass ratio of 1:10, and the mixture was stirred to form a suspension. The suspension was heated in a constant temperature water bath and stabilized at 80° C. The pH of the suspension was adjusted to 7.5 with 15% dilute hydrochloric acid to obtain a first suspension.

[0096] A magnesium chloride solution with a concentration of 135 g / L was added to the first suspension using a peristaltic pump, and a sodium hydroxide solution with a mass concentration of 5% was used to maintain a constant pH value. When the magnesium chloride coating rate reached 1%, the addition was stopped and stirring was continued for 20 minutes to obtain a second suspension.

[0097] The temperature of the second suspension was maintained and stably controlled at 80° C., and then a 95 g / L cerium nitrate solution was added. At the same time, a 5% by mass sodium hydroxide solution was used to balance the pH value to 8.0. When the coverage rate of the cerium nitrate reached 53%, the addition was stopped and stirring was continued for 20 minutes to obtain a third suspension.

[0098] The temperature of the third suspension was maintained and stably controlled at 80° C., and then a 100 g / L sodium metasilicate pentahydrate solution was added. At the same time, a 5% mass concentration of hydrochloric acid solution was used to balance the pH value to 8.0. When the coverage rate of sodium metasilicate pentahydrate reached 3.5%, the addition was stopped and stirring was continued for 20 minutes to obtain a fourth suspension.

[0099] The fourth suspension was vacuum filtered, the filter cake was washed with deionized water, and the filter cake was dried in an oven at 120°C; the dried filter cake powder was then placed in a muffle furnace, gradually heated to 800°C and calcined, and kept warm for 10 minutes. After the insulation was completed, the powder sample was taken out and naturally cooled to room temperature, then washed and dried to obtain a pearlescent pigment with a silvery white appearance (the coverage rates of the magnesium oxide layer, the high refractive index layer, and the protective layer on the substrate surface were detected to be approximately 0.41%, 27.52%, and 0.97%, respectively).

[0100] Example 9

[0101] 100 g of synthetic mica powder with a particle size range of 10-60 μm was placed in a 2 L reactor, deionized water was added at a solid-liquid mass ratio of 1:10, and the mixture was stirred to form a suspension. The suspension was heated in a constant temperature water bath and stabilized at 80° C. The pH of the suspension was adjusted to 7.5 with 15% dilute hydrochloric acid to obtain a first suspension.

[0102] A magnesium chloride solution with a concentration of 135 g / L was added to the first suspension using a peristaltic pump, and a sodium hydroxide solution with a mass concentration of 5% was used to maintain a constant pH value. When the magnesium chloride coating rate reached 3%, the addition was stopped and stirring was continued for 20 minutes to obtain a second suspension.

[0103] The temperature of the second suspension was maintained and stably controlled at 80° C., and then a zinc chloride solution with a concentration of 75 g / L was added. At the same time, a dilute hydrochloric acid solution with a mass concentration of 5% was used to balance the pH value to 6.5. When the coverage rate of zinc chloride reached 47%, the addition was stopped and stirring was continued for 20 minutes to obtain a third suspension.

[0104] The temperature of the third suspension was maintained and stably controlled at 80° C., and then a 100 g / L sodium metasilicate pentahydrate solution was added. At the same time, a 5% mass concentration of hydrochloric acid solution was used to balance the pH value to 8.0. When the coverage rate of sodium metasilicate pentahydrate reached 3.5%, the addition was stopped and stirring was continued for 20 minutes to obtain a fourth suspension.

[0105] The fourth suspension was vacuum filtered, the filter cake was washed with deionized water, and the filter cake was dried in an oven at 120°C; the dried filter cake powder was then placed in a muffle furnace, gradually heated to 800°C and calcined, and kept warm for 10 minutes. After the insulation was completed, the powder sample was taken out and naturally cooled to room temperature, then washed and dried to obtain a pearlescent pigment with a silvery white appearance (the coverage rates of the magnesium oxide layer, the high refractive index layer, and the protective layer on the substrate surface were detected to be approximately 1.22%, 27.57%, and 0.99%, respectively).

[0106] Example 10

[0107] 100 g of synthetic mica powder with a particle size range of 10-60 μm was placed in a 2 L reactor, deionized water was added at a solid-liquid mass ratio of 1:10, and the mixture was stirred to form a suspension. The suspension was heated in a constant temperature water bath and stabilized at 80° C. The pH of the suspension was adjusted to 7.5 with 15% dilute hydrochloric acid to obtain a first suspension.

[0108] A magnesium chloride solution with a concentration of 135 g / L was added to the first suspension using a peristaltic pump, and a sodium hydroxide solution with a mass concentration of 5% was used to maintain a constant pH value. When the magnesium chloride coating rate reached 3%, the addition was stopped and stirring was continued for 20 minutes to obtain a second suspension.

[0109] The temperature of the second suspension was maintained and stably controlled at 80° C., and then a zirconium nitrate solution with a concentration of 95 g / L was added. At the same time, a sodium hydroxide solution with a mass concentration of 5% was used to balance the pH value to 8.0. When the coverage rate of the zirconium nitrate reached 77%, the addition was stopped and stirring was continued for 20 minutes to obtain a third suspension.

[0110] The temperature of the third suspension was maintained and stably controlled at 80° C., and then a 100 g / L sodium metasilicate pentahydrate solution was added. At the same time, a 5% mass concentration of hydrochloric acid solution was used to balance the pH value to 8.0. When the coverage rate of sodium metasilicate pentahydrate reached 3.5%, the addition was stopped and stirring was continued for 20 minutes to obtain a fourth suspension.

[0111] The fourth suspension was vacuum filtered, the filter cake was washed with deionized water, and the filter cake was dried in an oven at 120°C; the dried filter cake powder was then placed in a muffle furnace, gradually heated to 800°C and calcined, and kept warm for 10 minutes. After the insulation was completed, the powder sample was taken out and naturally cooled to room temperature, then washed and dried to obtain a pearlescent pigment with a silvery white appearance (the coverage rates of the magnesium oxide layer, the high refractive index layer, and the protective layer on the substrate surface were detected to be approximately 1.25%, 27.59%, and 0.97%, respectively).

[0112] Example 11

[0113] 100 g of synthetic mica powder with a particle size range of 10-60 μm was placed in a 2 L reactor, deionized water was added at a solid-liquid mass ratio of 1:10, and the mixture was stirred to form a suspension. The suspension was heated in a constant temperature water bath and stabilized at 80° C. The pH of the suspension was adjusted to 7.5 with 15% dilute hydrochloric acid to obtain a first suspension.

[0114] A magnesium chloride solution with a concentration of 135 g / L was added to the first suspension using a peristaltic pump, and a sodium hydroxide solution with a mass concentration of 5% was used to maintain a constant pH value. When the magnesium chloride coating rate reached 3%, the addition was stopped and stirring was continued for 20 minutes to obtain a second suspension.

[0115] The temperature of the second suspension was maintained and stably controlled at 80° C., and then a zinc chloride solution with a concentration of 75 g / L was added, and the equilibrium pH value was adjusted to 6.5 with 10% dilute hydrochloric acid. When the coverage rate of the zinc chloride reached 11%, the addition was stopped, and stirring was continued for 20 minutes. Then, a cerium nitrate solution with a concentration of 95 g / L was added, and the pH value was balanced to 8.0 with a sodium hydroxide solution with a mass concentration of 5%. When the coverage rate of the cerium nitrate reached 40%, the addition was stopped, and stirring was continued for 20 minutes to obtain a third suspension.

[0116] The temperature of the third suspension was maintained and stably controlled at 80° C., and then a 100 g / L sodium metasilicate pentahydrate solution was added. At the same time, a 5% mass concentration of hydrochloric acid solution was used to balance the pH value to 8.0. When the coverage rate of sodium metasilicate pentahydrate reached 3.5%, the addition was stopped and stirring was continued for 20 minutes to obtain a fourth suspension.

[0117] The fourth suspension was vacuum filtered, the filter cake was washed with deionized water, and the filter cake was dried in an oven at 120°C; the dried filter cake powder was then placed in a muffle furnace, gradually heated to 800°C and calcined, and kept warm for 10 minutes. After the insulation was completed, the powder sample was taken out and naturally cooled to room temperature, then washed and dried to obtain a pearlescent pigment with a silvery white appearance (the coverage rates of the magnesium oxide layer, the high refractive index layer, and the protective layer on the substrate surface were detected to be approximately 1.22%, 27.55%, and 0.98%, respectively).

[0118] Example 12

[0119] 100 g of synthetic mica powder with a particle size range of 10-60 μm was placed in a 2 L reactor, deionized water was added at a solid-liquid mass ratio of 1:10, and the mixture was stirred to form a suspension. The suspension was heated in a constant temperature water bath and stabilized at 80° C. The pH of the suspension was adjusted to 7.5 with 15% dilute hydrochloric acid to obtain a first suspension.

[0120] A magnesium chloride solution with a concentration of 135 g / L was added to the first suspension using a peristaltic pump, and a sodium hydroxide solution with a mass concentration of 5% was used to maintain a constant pH value. When the magnesium chloride coverage rate reached 18%, the addition was stopped and stirring was continued for 20 minutes to obtain a second suspension.

[0121] The temperature of the second suspension was maintained and stably controlled at 80° C., and then a 95 g / L cerium nitrate solution was added. At the same time, a 5% by mass sodium hydroxide solution was used to balance the pH value to 8.0. When the coverage rate of the cerium nitrate reached 53%, the addition was stopped and stirring was continued for 20 minutes to obtain a third suspension.

[0122] The temperature of the third suspension was maintained and stably controlled at 80° C., and then a 100 g / L sodium metasilicate pentahydrate solution was added. At the same time, a 5% mass concentration hydrochloric acid solution was used to balance the pH value to 8.0. When the coverage rate of sodium metasilicate pentahydrate reached 3.5%, the addition was stopped and stirring was continued for 20 minutes to obtain a fourth suspension.

[0123] The fourth suspension was vacuum filtered, the filter cake was washed with deionized water, and the filter cake was dried in an oven at 120°C; the dried filter cake powder was then placed in a muffle furnace, gradually heated to 800°C and calcined, and kept warm for 10 minutes. After the insulation was completed, the powder sample was taken out and naturally cooled to room temperature, then washed and dried to obtain a pearlescent pigment (the coverage rates of the magnesium oxide layer, the high refractive index layer, and the protective layer on the substrate surface were detected to be approximately 7.51%, 27.54%, and 0.98%, respectively).

[0124] Example 13

[0125] Example 12 was repeated except that the coverage of magnesium chloride was 0.4% (the coverage of the magnesium oxide layer, high refractive index layer, and protective layer on the substrate surface was detected to be approximately 0.16%, 27.58%, and 0.97%, respectively).

[0126] Example 14

[0127] 100 g of synthetic mica powder with a particle size range of 10-60 μm was placed in a 2 L reactor, deionized water was added at a solid-liquid mass ratio of 1:10, and the mixture was stirred to form a suspension. The suspension was heated in a constant temperature water bath and stabilized at 80° C. The pH of the suspension was adjusted to 7.5 with 15% dilute hydrochloric acid to obtain a first suspension.

[0128] A magnesium chloride solution with a concentration of 135 g / L was added to the first suspension using a peristaltic pump, and a sodium hydroxide solution with a mass concentration of 5% was used to maintain a constant pH value. When the magnesium chloride coating rate reached 3%, the addition was stopped and stirring was continued for 20 minutes to obtain a second suspension.

[0129] The temperature of the second suspension was maintained and stably controlled at 80° C., and then a 95 g / L cerium nitrate solution was added. At the same time, a 5% by mass sodium hydroxide solution was used to balance the pH value to 8.0. When the coverage rate of the cerium nitrate reached 10%, the addition was stopped and stirring was continued for 20 minutes to obtain a third suspension.

[0130] The temperature of the third suspension was maintained and stably controlled at 80° C., and then a 100 g / L sodium metasilicate pentahydrate solution was added. At the same time, a 5% mass concentration of hydrochloric acid solution was used to balance the pH value to 8.0. When the coverage rate of sodium metasilicate pentahydrate reached 3.5%, the addition was stopped and stirring was continued for 20 minutes to obtain a fourth suspension.

[0131] The fourth suspension was vacuum filtered, the filter cake was washed with deionized water, and the filter cake was dried in an oven at 120°C; the dried filter cake powder was then placed in a muffle furnace, gradually heated to 800°C and calcined, and kept warm for 10 minutes. After the insulation was completed, the powder sample was taken out and naturally cooled to room temperature, then washed and dried to obtain a pearlescent pigment (the coverage rates of the magnesium oxide layer, the high refractive index layer, and the protective layer on the substrate surface were detected to be approximately 1.23%, 5.19%, and 0.99%, respectively).

[0132] Example 15

[0133] Example 1 was repeated except that sodium metasilicate pentahydrate was replaced by aluminum chloride.

[0134] Example 16

[0135] Example 1 was repeated except that cerium nitrate was replaced by cerium chloride.

[0136] Example 17

[0137] Example 1 was repeated except that zinc chloride was replaced by zinc nitrate.

[0138] Example 18

[0139] Example 1 was repeated except that the magnesium chloride was replaced by magnesium sulfate.

[0140] Comparative Example 1

[0141] 100 g of synthetic mica powder with a particle size range of 10-60 μm was placed in a 2 L reactor, deionized water was added at a solid-liquid mass ratio of 1:10, and the mixture was stirred to form a suspension. The suspension was heated in a constant temperature water bath and stabilized at 80° C. The pH of the suspension was adjusted to 7.5 with 15% dilute hydrochloric acid to obtain a first suspension.

[0142] The temperature of the first suspension was maintained and stably controlled at 80° C. A 95 g / L cerium nitrate solution was added to the first suspension using a peristaltic pump. At the same time, a 5% by mass sodium hydroxide solution was used to balance the pH value to 8.0. When the coverage rate of the cerium nitrate reached 53%, the addition was stopped and stirring was continued for 20 minutes to obtain a second suspension.

[0143] The temperature of the second suspension was maintained and stably controlled at 80° C., and then a 100 g / L sodium metasilicate pentahydrate solution was added. At the same time, a 5% mass concentration hydrochloric acid solution was used to balance the pH value to 8.0. When the coverage rate of sodium metasilicate pentahydrate reached 3.5%, the addition was stopped and stirring was continued for 20 minutes to obtain a third suspension.

[0144] The third suspension was vacuum filtered, the filter cake was washed with deionized water, and the filter cake was dried in an oven at 120°C; the dried filter cake powder was then placed in a muffle furnace, gradually heated to 800°C and calcined, and kept warm for 10 minutes. After the insulation was completed, the powder sample was taken out and naturally cooled to room temperature, then washed and dried to obtain a pearlescent pigment (the coverage rates of the high refractive index layer and the protective layer on the substrate surface were detected to be approximately 27.50% and 0.96%, respectively).

[0145] Comparative Example 2

[0146] 100 g of synthetic mica powder with a particle size range of 10-60 μm was placed in a 2 L reactor, deionized water was added at a solid-liquid mass ratio of 1:10, and the mixture was stirred to form a suspension. The suspension was heated in a constant temperature water bath and stabilized at 80° C. The pH of the suspension was adjusted to 7.5 with 15% dilute hydrochloric acid to obtain a first suspension.

[0147] A 135 g / L calcium chloride solution was added to the first suspension using a peristaltic pump, and a 5% mass concentration sodium hydroxide solution was used to maintain a constant pH value. When the calcium chloride coating rate reached 2.6%, the addition was stopped and stirring was continued for 20 minutes to obtain a second suspension.

[0148] The temperature of the second suspension was maintained and stably controlled at 80° C., and then a 95 g / L cerium nitrate solution was added. At the same time, a 5% by mass sodium hydroxide solution was used to balance the pH value to 8.0. When the coverage rate of the cerium nitrate reached 53%, the addition was stopped and stirring was continued for 20 minutes to obtain a third suspension.

[0149] The temperature of the third suspension was maintained and stably controlled at 80° C., and then a 100 g / L sodium metasilicate pentahydrate solution was added. At the same time, a 5% mass concentration hydrochloric acid solution was used to balance the pH value to 8.0. When the coverage rate of sodium metasilicate pentahydrate reached 3.5%, the addition was stopped and stirring was continued for 20 minutes to obtain a fourth suspension.

[0150] The fourth suspension was vacuum filtered, the filter cake was washed with deionized water, and the filter cake was dried in an oven at 120°C; the dried filter cake powder was then placed in a muffle furnace, gradually heated to 800°C for calcination, and kept warm for 10 minutes. After the insulation was completed, the powder sample was taken out and naturally cooled to room temperature, then washed and dried to obtain a pearlescent pigment (the coverage rates of the calcium oxide layer, high refractive index layer, and protective layer on the substrate surface were detected to be approximately 1.26%, 27.55%, and 0.99%, respectively).

[0151] Comparative Example 3

[0152] 100 g of synthetic mica powder with a particle size range of 10-60 μm was placed in a 2 L reactor, deionized water was added at a solid-liquid mass ratio of 1:10, and the mixture was stirred to form a suspension. The suspension was heated in a constant temperature water bath and stabilized at 80° C. The pH of the suspension was adjusted to 7.5 with 15% dilute hydrochloric acid to obtain a first suspension.

[0153] A 95 g / L cerium nitrate solution was added to the first suspension using a peristaltic pump, and a 5% mass concentration sodium hydroxide solution was used to balance the pH to 8.0. When the coverage rate of cerium nitrate reached 53%, the addition was stopped and stirring was continued for 20 minutes to obtain a second suspension.

[0154] The temperature of the second suspension was maintained and stably controlled at 80° C., and then a magnesium chloride solution with a concentration of 135 g / L was added. At the same time, a sodium hydroxide solution with a mass concentration of 5% was used to maintain a constant pH value. When the magnesium chloride coverage reached 3%, the addition was stopped and stirring was continued for 20 minutes to obtain a third suspension.

[0155] The temperature of the third suspension was maintained and stably controlled at 80° C., and then a 100 g / L sodium metasilicate pentahydrate solution was added. At the same time, a 5% mass concentration of hydrochloric acid solution was used to balance the pH value to 8.0. When the coverage rate of sodium metasilicate pentahydrate reached 3.5%, the addition was stopped and stirring was continued for 20 minutes to obtain a fourth suspension.

[0156] The fourth suspension was vacuum filtered, the filter cake was washed with deionized water, and the filter cake was dried in an oven at 120°C; the dried filter cake powder was then placed in a muffle furnace, gradually heated to 800°C and calcined, and kept warm for 10 minutes. After the insulation was completed, the powder sample was taken out and naturally cooled to room temperature, then washed and dried to obtain a pearlescent pigment (the coverage rates of the high refractive index layer, magnesium oxide layer, and protective layer on the substrate surface were detected to be approximately 27.53%, 1.22%, and 0.99%, respectively).

[0157] Comparative Example 4

[0158] 100 g of synthetic mica powder with a particle size range of 10-60 μm was placed in a 2 L reactor, deionized water was added at a solid-liquid mass ratio of 1:10, and the mixture was stirred to form a suspension. The suspension was heated in a constant temperature water bath and stabilized at 80° C. The pH of the suspension was adjusted to 7.5 with 15% dilute hydrochloric acid to obtain a first suspension.

[0159] A magnesium chloride solution with a concentration of 135 g / L was added to the first suspension using a peristaltic pump, and a sodium hydroxide solution with a mass concentration of 5% was used to maintain a constant pH value. When the magnesium chloride coating rate reached 3%, the addition was stopped and stirring was continued for 20 minutes to obtain a second suspension.

[0160] The temperature of the second suspension was maintained and stably controlled at 80° C., and then a 95 g / L cerium nitrate solution was added. At the same time, a 5% by mass sodium hydroxide solution was used to balance the pH value to 8.0. When the coverage rate of the cerium nitrate reached 53%, the addition was stopped and stirring was continued for 20 minutes to obtain a third suspension.

[0161] The third suspension was vacuum filtered, the filter cake was washed with deionized water, and the filter cake was dried in an oven at 120°C; the dried filter cake powder was then placed in a muffle furnace, gradually heated to 800°C and calcined, and kept warm for 10 minutes. After the insulation was completed, the powder sample was taken out and naturally cooled to room temperature, then washed and dried to obtain a pearlescent pigment (the coverage rates of the magnesium oxide layer and the high refractive index layer on the substrate surface were detected to be approximately 1.24% and 27.57%, respectively).

[0162] Comparative Example 5

[0163] 100 g of synthetic mica powder with a particle size range of 10-60 μm was placed in a 2 L reactor, deionized water was added at a solid-liquid mass ratio of 1:10, and the mixture was stirred to form a suspension. The suspension was heated in a constant temperature water bath and stabilized at 65° C. The pH of the suspension was adjusted to 1.5 with 15% dilute hydrochloric acid to obtain a first suspension.

[0164] A 235 g / L tin chloride solution was added to the first suspension using a peristaltic pump without constant pH. When the SnO2 coating rate reached 3%, the addition was stopped and stirring was continued for 20 minutes to obtain a second suspension.

[0165] The temperature of the second suspension was adjusted and stably controlled at 80°C, the pH value was adjusted to 1.8 with 30% mass concentration of sodium hydroxide, and a 2 mol / L titanium tetrachloride solution was added. At the same time, the pH value was balanced to 1.8 with 30% mass concentration of sodium hydroxide solution. When the TiO2 coverage rate reached 25%, the addition was stopped and stirring was continued for 20 minutes to obtain a third suspension.

[0166] The third suspension was vacuum filtered, and the filter cake was washed with deionized water. The filter cake was then dried in an oven at 120°C. The dried filter cake powder was then placed in a muffle furnace, gradually heated to 800°C, and calcined for 10 minutes. After the heat preservation was completed, the powder sample was removed and naturally cooled to room temperature, then washed and dried to obtain a mica titanium pearlescent pigment with a silvery white appearance.

[0167] Effect Test Example 1

[0168] The pearlescent pigment powders obtained in Examples 1-14 and Comparative Examples 1-5 were coated on a card and their dispersibility was observed. The data were then tested using an X-Rite MA98. The results are shown in Table 1 below:

[0169] Table 1:

[0170] It can be seen that the color data of Examples 1-14 and Comparative Examples 1-5 are basically the same, and the hues are basically consistent. The difference lies in the deposition agents and their coverage rates.

[0171] The D65 / 10°Lab data measured by the X-Rite MA98 colorimeter is shown in Table 2 below:

[0172] Table 2:

[0173] Wherein, L* is brightness, and a* and b* are color. Experimental results show that compared with existing titanium-containing pearlescent pigments, the L, a, and b data of the titanium-free silver white pearlescent pigment of the present invention are not significantly different, and have a better pearlescent effect.

[0174] The pearlescent pigment powders of Examples 1-14 and Comparative Examples 1-5 were sent to SGS for testing and evaluation of heavy metals, SPF values, and UVA PF values. The specific test results are shown in Table 3:

[0175] Table 3: Comparison of SPF and UVA PF values:

[0176] It can be seen that the SPF values ​​and UVA PF values ​​of Examples 1-11 are greater than those of Comparative Example 5. The SPF values ​​increase by about 10% to 30% year-on-year, and the UVA PF values ​​increase by about 20% to 45% year-on-year, which is a large increase.

[0177] Table 4 is SGS heavy metal detection data (Example 1)

[0178] In summary, the titanium-free silver-white pearlescent pigment of the present invention passes the heavy metal test; compared with mica titanium pearlescent pigment, it has excellent ultraviolet resistance, and the SPF value and UVA PF value are both larger. The SPF value is increased by 10% to 30% compared with mica titanium pearlescent pigment, and the UVA PF value is increased by 20% to 45% compared with mica titanium pearlescent pigment, which is a large increase. It can effectively alleviate the common color change and color migration phenomena of pearlescent pigments during the production and application process; and the skin feels softer and smoother, without roughness or paleness.

Claims

1. A titanium-free silver-white pearlescent pigment, characterized in that: The pearlescent pigment comprises: a substrate, a magnesium oxide layer coated and deposited on the surface of the substrate, a high refractive index layer coated and deposited on the surface of the magnesium oxide layer, and a protective layer coated and deposited on the surface of the high refractive index layer.

2. The pearlescent pigment according to claim 1, characterized in that: The substrate is one of mica, glass flakes, SiO2 flakes, Al2O3 flakes and bismuth oxychloride, preferably one of mica flakes, glass flakes, SiO2 flakes, Al2O3 flakes and bismuth oxychloride flakes, more preferably natural mica powder or synthetic mica powder or glass flake powder; and / or The high refractive index layer is a metal oxide layer with a refractive index greater than 1.8, the metal oxide is preferably one of ZrO2, CeO2, and ZnO, and the metal oxide is more preferably CeO2 and / or ZnO; and / or The protective layer is one or more of SiO2, Al2O3, and a silane compound, preferably SiO2 and / or Al2O3, and more preferably SiO2; preferably, the silane compound is selected from one or more of (3-glycidyloxypropyl)trimethoxysilane, (3-aminopropyl)triethoxysilane, methacrylpropylmethoxysilane, 3-(2-aminoethylamino)propyltrimethoxysilane, methyltriethoxysilane, and n-hexyltrimethoxysilane.

3. The pearlescent pigment according to claim 1 or 2, characterized in that: The coverage rate of the magnesium oxide layer is 0.2-6%, preferably 0.5-5%, more preferably 1-4%; and / or The coverage of the high refractive index layer is 10-45%, preferably 15-40%, more preferably 20-35%; and / or The coverage rate of the protective layer is 0.05-7%, preferably 0.1-6%, and more preferably 0.3-5%.

4. The pearlescent pigment according to any one of claims 1 to 3, characterized in that: The thickness of the substrate is 50-500 nm, preferably 75-450 nm, more preferably 100-400 nm; the particle size of the substrate is ≤500 μm, preferably ≤300 μm, more preferably ≤250 μm.

5. A method for preparing a titanium-free silver-white pearlescent pigment or a method for preparing a titanium-free silver-white pearlescent pigment as claimed in any one of claims 1 to 4, characterized in that: The preparation method comprises: 1) dispersing the substrate in a dispersion to obtain a first suspension; 2) adding a soluble magnesium salt solution to the first suspension to obtain a second suspension; 3) adding a soluble metal salt solution to the second suspension to obtain a third suspension; 4) adding a soluble protective salt solution to the third suspension to obtain a fourth suspension; 5) The fourth suspension is filtered, washed, dried, calcined and sieved in sequence to obtain a titanium-free silver-white pearlescent pigment.

6. The method according to claim 5, characterized in that: The dispersion liquid is deionized water, and the liquid-to-solid mass ratio of the dispersion liquid to the added amount of the substrate is 3-20:1, preferably 5-15:1, and more preferably 7-12:1; and / or The soluble magnesium salt is one or more of magnesium nitrate, magnesium sulfate, and magnesium chloride; the concentration of the soluble magnesium salt solution is 25-600 g / L, preferably 50-300 g / L, and more preferably 80-200 g / L; the amount of the soluble magnesium salt solution added is such that the coverage rate of the soluble magnesium salt on the surface of the substrate in the second suspension is 0.5-15%, preferably 0.8-12%, and more preferably 1-10％。 7. The method according to claim 5 or 6, characterized in that: The soluble metal salt is one or more of cerium nitrate, cerium chloride, cerium sulfate, zinc nitrate, zinc sulfate, and zinc chloride, preferably a mixed salt composed of one or more of cerium nitrate, cerium chloride, cerium sulfate and one or more of zinc nitrate, zinc sulfate, and zinc chloride, and more preferably a mixed salt composed of cerium nitrate and zinc chloride; the concentration of the soluble metal salt solution is 80-700 g / L, preferably 100-500 g / L, and more preferably 120-300 g / L; the amount of the soluble metal salt solution added is such that the coverage rate of the soluble metal salt in the third suspension is 25-88%, preferably 30-80%, and more preferably 35-75%.

8. The method according to any one of claims 5 to 7, characterized in that: The soluble protective salt is one or more of aluminum chloride, aluminum nitrate, aluminum sulfate, sodium metasilicate pentahydrate, sodium metasilicate nonahydrate, and silane compounds, preferably aluminum chloride and / or sodium metasilicate pentahydrate, and more preferably sodium metasilicate pentahydrate; the concentration of the soluble protective salt solution is 30-250 g / L, preferably 40-200 g / L, and more preferably 50-180 g / L; the amount of the soluble protective salt solution added is such that the coverage rate of the soluble protective salt in the fourth suspension is 0.1-20%, preferably 0.5-15%, and more preferably 0.8-10%.

9. The method according to claim 8, characterized in that: Step 1) is specifically as follows: dispersing the substrate in the dispersion in proportion, stirring and mixing thoroughly, heating to 50-90° C. (preferably 75-85° C.) and maintaining a constant temperature, and using an acid or alkali (e.g., a hydrochloric acid solution with a mass concentration of 5-18% or a sodium hydroxide solution with a mass concentration of 5-15%) to adjust the pH of the system to 7-9 (preferably 7.5-8.5) to obtain a first suspension; and / or Step 2) is specifically: adding a soluble magnesium salt solution to the first suspension in proportion, controlling the temperature to 65-90° C. (preferably 75-85° C.), and using an acid or base (for example, a hydrochloric acid solution with a mass concentration of 5-18% or a sodium hydroxide solution with a mass concentration of 5-15%) to adjust the pH of the system to 7-9 (preferably 7.5-8.5) to obtain a second suspension; and / or Step 3) is specifically: adding a soluble metal salt solution to the second suspension in proportion, controlling the temperature to 65-90° C. (preferably 75-85° C.), and using an acid or base (e.g., a hydrochloric acid solution with a mass concentration of 5-18% or a sodium hydroxide solution with a mass concentration of 5-15%) to adjust the system pH to 5-9 (preferably 5.5-8.5) to obtain a third suspension; and / or Step 4) is specifically as follows: adding a soluble protective salt solution to the third suspension in proportion, controlling the temperature to 65-90° C. (preferably 75-85° C.), and adjusting the pH of the system to 7-10 (preferably 7.5-9) using an acid or base (e.g., a hydrochloric acid solution with a mass concentration of 5-18% or a sodium hydroxide solution with a mass concentration of 5-15%) to obtain a fourth suspension; Step 5) is specifically as follows: the fourth suspension is filtered and washed, and then dried in an oven at 80-150°C (preferably 100-135°C). After drying, it is calcined at 700-900°C (preferably 750-850°C) for 1-15min (preferably 2-10min) and sieved to obtain a titanium-free silver white pearlescent pigment.

10. Use of a titanium-free silver-white pearlescent pigment or the use of the titanium-free silver-white pearlescent pigment as claimed in any one of claims 1 to 4 or the use of the titanium-free silver-white pearlescent pigment prepared by the method as claimed in any one of claims 5 to 9, characterized in that: The titanium-free silver-white pearlescent pigment is used to prepare one or more of coatings, inks, plastics, and cosmetics; preferably, the titanium-free silver-white pearlescent pigment is used to prepare one or more of lip gloss, eye shadow, pressed powder, nail polish, lotion, face cream, shampoo, cleansing cream, and handmade soap.

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