CN102260421A - Magic-color nacreous aluminum powder pigment and preparation method thereof - Google Patents

Abstract

The invention discloses an aluminum powder pigment with iridescent pearl luster and a preparation method thereof. The method uses aluminum powder with an average particle size of 10 μm to 150 μm and a surface coated with SiO ₂ film as the substrate raw material. The SiO ₂ film is inert, acid-resistant, heat-resistant, and transparent. Under the condition of 60 ℃ ~ 80 ℃, deposit a layer of nano titanium dioxide film on the transparent SiO ₂ film by chemical liquid phase deposition, wash and dry, and bake the pigment at 500 ℃ ~ 600 ℃ under the protection of inert gas 0.5~1.0h, the high-gloss pearly illusion aluminum powder pigment with TiO ₂ /SiO ₂ /Al-based composite film is prepared. The pigment also has excellent comprehensive properties such as the illusion interference effect of pearlescent pigments and the conductivity, high hiding power, shielding and non-toxic environmental protection of metal aluminum powder pigments. It has unique decorative effects and can be widely used in high-end automotive topcoats and high-end decorations. Products, surface coating of high-end instruments, ink printing, children's toys, etc. The method of the invention is simple and feasible, and has industrial feasibility.

Description

Pearlescent illusion aluminum powder pigment and preparation method thereof

technical field

The invention relates to the technical field of novel decorative colored metallic pigments, in particular to a pearlescent iridescent aluminum powder pigment and a preparation method thereof.

Background technique

Pearlescent Symphony Aluminum Powder Pigment is a new type of pigment that is prepared by coating a layer of nano-titanium dioxide film with high refractive index on the surface of silicified flake aluminum powder substrate, and using the interference phenomenon of light on the metal oxide film. Inorganic non-metallic/metallic composite material—aluminum-based magic pearlescent pigment. The new pigment has the following characteristics :

(1) It has satin-like pearl luster or bright and shimmering metallic luster and color-flop effect. Metal aluminum has good ductility, and it is easy to make flake aluminum powder with regular shape, uniform particle size distribution and large diameter-to-thickness ratio. It is a good substrate raw material. Similar to the mica titanium pearlescent pigment prepared with flake mica powder as the substrate, after compounding the titanium dioxide layer with high refractive index on the surface of the flake aluminum powder, the light will produce multiple reflections, projections and refractions at the film interface, which can produce strong pearlescent luster. By controlling different thicknesses of TiO ₂ coatings, the pigments can present a variety of interference colors such as gold, red, purple, blue, and green, which can change the monotonous gray metallic appearance of aluminum powder pigments. The combination of high brightness, high chroma and remarkable flash can make the decorations produce dazzling illusion effect, and has good decorative performance.

(2) High hiding power and excellent shielding property. Flake aluminum powder has a smooth surface, strong metallic luster, specular reflection of light and good ability to reflect heat radiation. It can form a continuous metal film in the coating, which can reflect visible light, ultraviolet rays and infrared rays, making it have the ability to reflect heat radiation. Insulation performance and protection of the coating from ultraviolet damage, prolonging the life of the coating, shielding the excellent protective effect of external gas, moisture, light and other erosion, especially suitable for high-end automotive topcoats.

(3) Strong light resistance, weather resistance, heat resistance and chemical resistance. The heat resistance and chemical inertness of pearlescent aluminum powder coated with inorganic metal oxide film are significantly improved, and it is not easy to oxidize, resist water, dilute acid, organic solvent and vulcanization. Compared with ordinary aluminum powder, it can be used in higher High temperature occasions and relatively harsh conditions, its adaptability is stronger and its application range is wider.

(4) With excellent electrical conductivity, it can be used in occasions with special requirements such as electrical conductivity and heat radiation reflectivity.

(5) Good hydrophilicity and good dispersion in water-based paints.

(6) It is non-toxic and can be used in food utensils, food packaging and children's toys.

To sum up, pearlescent aluminum powder pigment is a new type of material with excellent decorative properties and various special properties, and it has a wide range of uses. However, it is very difficult to prepare pearlescent magic color aluminum powder pigments by coating titanium oxide with ordinary aluminum powder as the substrate. Because the deposition of titanium dioxide on the substrate is generally carried out in a hot acidic liquid phase, and aluminum powder is very active, extremely not resistant to acid, and even less resistant to acid liquid under heating, it is difficult to obtain aluminum-based pearlescent illusion by chemical liquid deposition. pigment. In 1990, the German BASF company adopted the vapor phase deposition method. In the fluidized bed reactor, the aluminum powder was fluidized with an inert gas, and TiCl ₄ was passed into it, and it reacted at about 200 ° C to form colorless TiO ₂ and deposited on the surface of the aluminum powder. Aluminum-based pigments with iridescent shades (US 4978394) . This method requires large equipment investment, long reaction time, small batch size, high cost, and difficulty in large-scale production; Zhou Yi and others once used oxidation reaction to form a very thin and uniform oxide film on the surface of aluminum powder, and then applied it on the surface of the oxide film. Adsorb organic pigments to make colorful aluminum powder (see "A Preliminary Study on Chemical Coloring of Aluminum Powder", Zhou Yi, Jia Yangang, Yinshan Academic Journal, No. 2, 1995, P 30~33). Its colored aluminum powder is mainly developed by colored substances, and the optical interference effect is not significant; Wu Yin et al. used organic coating method to coat polymethyl methacrylate on the surface of aluminum powder at pH=9 and 70°C to obtain a golden color. Aluminum powder pigment with flashing effect (see "Research on Preparation of Golden Flashing Aluminum Powder Pigment", Wu Yin, Li Fengsheng, Bai Huaping, etc., Journal of Materials Science and Engineering, No. 6, 2006, P923~925), but coated on the surface of aluminum powder The covered PMMA film is not a crystal structure, and the pearl luster effect of the product is not obvious.

For this reason, the present invention adopts the flaky aluminum powder of siliconization treatment as substrate raw material. The surface of this aluminum powder is coated with a layer of inert and transparent _SiO2 film, which can not only maintain the metallic luster of the aluminum powder pigment, but also be resistant to acidic environments. (See "Research on SiO ₂ Film Coated on the Surface of Flaky Aluminum Powder", Ye Hongqi, Chen Jiana, Liu Hui, etc., Shanghai Paint, No. 10, 2006, p15~18). The SiO ₂ film on the surface of the aluminum powder has the characteristics of acid resistance, heat resistance and transparency, and a layer of nano-titanium dioxide film is coated on the SiO ₂ film by the liquid phase deposition method, and the composite method of TiO ₂ /SiO ₂ /Al is prepared. High gloss pearlescent aluminum powder pigment. The method is simple and feasible, and has industrial feasibility.

Contents of the invention

The object of the present invention is to provide a kind of aluminum powder pigment with magic pearl luster and its preparation method.

The purpose of the present invention is achieved through the following technical solutions.

A kind of preparation method of the aluminum powder pigment with magic color pearl luster is:

Step 1: In terms of mass fraction, add 4-10 parts of silicon-coated flake aluminum powder with a diameter of 10-150 μm in the reaction vessel, add 50-100 parts of water, and stir fully to form an aluminum powder suspension.

The second step is to adjust the pH value of the aluminum powder suspension between 1.5 and 2.5, and slowly raise the temperature of the suspension to 50 ° C ~ 80 ° C, slowly add titanium salt solution to the suspension under stirring conditions, and at the same time add dilute The lye is used to maintain the stability of the pH value of the suspension, so that the titanium salt solution can be slowly hydrolyzed into hydrated titanium dioxide and evenly deposited on the surface of the aluminum powder. After the hydrated titanium dioxide is deposited to a certain thickness and reaches the required interference color, stop adding titanium solution and lye, and continue to stir for 0.5~1.0h before stopping the reaction.

The third step is to filter the pigment, wash it to neutral, and dry it at about 110℃~120℃.

The fourth step is to place the dried aluminum powder pigment in a calciner, introduce an inert gas, and slowly raise the temperature from room temperature to 500~600°C, and roast at this temperature for 0.5~1.0h to obtain the aluminum-based pearlescent illusion pigment .

The preparation method of the aluminum-based magic color pearlescent pigment provided by the present invention has the following characteristics:

1. Using aluminum powder coated with SiO ₂ film on the surface as the pigment substrate solves the problem that the aluminum powder has active chemical properties and is easily corroded under acidic conditions, so that the subsequent hydrolytic deposition of titanium salt can proceed smoothly.

2. Using the chemical liquid phase deposition method, deposit and coat nano-titanium dioxide on the surface of aluminum powder coated with transparent SiO ₂ film, and prepare pearlescent magic color aluminum powder pigment with high gloss by TiO ₂ /SiO ₂ /Al-based composite method. The chemical liquid phase deposition process is simple and easy, the equipment is simple, the raw material of titanium tetrachloride is cheap and easy to obtain, and it can be produced in a large scale. A series of pearlescent iridescent aluminum powder pigments with different interference colors can be prepared by controlling the different thicknesses of the titanium dioxide coating.

3. The aluminum powder pigment coated with hydrated _TiO2 needs to be calcined to dehydrate the hydrated titanium dioxide into a crystal film on the outer surface of _TiO2 with pigment characteristics, so as to produce a strong optical interference effect. Aluminum powder is very easy to oxidize and lose luster at high temperature, and the present invention uses inert gas protection during calcination to ensure the high gloss of the pearly illusion aluminum powder pigment.

4. The pearlescent magic color aluminum powder pigment prepared by the present invention has the colorful beauty of pearlescent pigments, high refractive index, light and weather resistance, good chemical stability and the unique strong metallic luster, conductivity, high hiding power, Excellent comprehensive properties such as shielding and floating properties, non-toxic and environmental protection, etc., can be widely used in high-end automotive topcoats, high-end decorations, surface coating of high-end instruments, ink printing, children's toys, etc. Its unique optical properties and decorative effects, It can greatly enhance the value of the decorated products.

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Detailed ways

Example 1

Add 10g of silicon-coated aluminum powder pigment with a diameter of 10~60μm into the reaction vessel, add 100g of water, and stir well to form aluminum powder suspension. Adjust the pH value of the suspension to 1.8±0.3, slowly raise the temperature of the suspension to 60°C±5°C, and slowly add the _TiCl4 solution (the content of _TiCl4 is 50g /L), and dropwise add NaOH aqueous solution (NaOH content is 50g/L) simultaneously, to maintain the pH value stability of suspension, make titanium salt slowly hydrolyze into hydrated titanium dioxide and evenly deposit on the surface of aluminum powder, when _TiCl solution adds 70ml , the pigment presents a strong silvery interference color, stop adding the titanium solution and lye, and continue to stir for 30 minutes to stop the reaction. The pigment is filtered, washed until neutral, and dried at about 110°C. Put the dried aluminum powder pigment in a calcination furnace, feed nitrogen gas, slowly raise the temperature from room temperature to 500°C±20°C, and roast at this temperature for 60 minutes to obtain silver pearlescent aluminum powder pigment.

Example 2

Add 5.0g of silicon-coated aluminum powder pigment with a diameter of 10-60μm into the reaction vessel, add 80g of water, and stir well to form an aluminum powder suspension. Adjust the pH value of the suspension to 2.2 ± 0.3, slowly raise the temperature of the suspension to 70 °C ± 5 °C, and slowly add _TiCl4 solution (with a content of 50 g/min) to the suspension at a rate of 0.8 ml/min under stirring. L), and dropwise NaOH aqueous solution (content is 50g/L) simultaneously, to maintain the stable pH value of suspension, make titanium salt solution slowly hydrolyze into hydrated titanium dioxide and evenly deposit on the surface of aluminum powder, when _TiCl solution adds 60ml , the pigment presents a golden interference color, stop adding the titanium solution and lye, and continue stirring for 30 minutes to stop the reaction. The pigment is filtered, washed until neutral, and dried at about 120°C. Put the dried aluminum powder pigment in a calcination furnace, blow in nitrogen gas, slowly raise the temperature from room temperature to 550°C±20°C, and roast at this temperature for 45 minutes to obtain the golden pearlescent magic color aluminum powder pigment.

Example 3

Add 10g of silicon-coated aluminum powder pigment with a diameter of 10~150μm into the reaction vessel, add 100g of water, and stir well to form aluminum powder suspension. Adjust the pH value of the suspension to 2.0 ± 0.3, slowly raise the temperature of the suspension to 80 °C ± 5 °C, and slowly add _TiCl4 solution (with a content of 50 g/min) to the suspension at a rate of 1.0 ml/min under stirring. L), and dropwise NaOH aqueous solution (content is 50g/L) simultaneously, to maintain the stable pH value of suspension, titanium salt solution is slowly hydrolyzed into hydrated titanium dioxide and is evenly deposited on the surface of aluminum powder, when _TiCl solution adds 75ml , the pigment presents a red interference color, stop adding the titanium solution and lye, continue to stir for 30 minutes and then stop the reaction. The pigment is filtered, washed until neutral, and dried at about 110°C. Put the dried aluminum powder pigment in a calciner, feed nitrogen gas, slowly raise the temperature from room temperature to 600°C ± 20°C, and roast at this temperature for 45 minutes to obtain golden red pearlescent aluminum powder pigment.

Example 4

Add 10g of silicon-coated aluminum powder pigment with a diameter of 10~40μm into the reaction vessel, add 100g of water, and stir well to form aluminum powder suspension. Adjust the pH value of the suspension to 2.0 ± 0.3, slowly raise the temperature of the suspension to 75 ° C ± 5 ° C, and slowly add TiCl ₄ solution (TiCl ₄ content is 50g/L), and add NaOH aqueous solution (NaOH content is 50g/L) dropwise at the same time, to maintain the pH value of the suspension stable, so that the titanium salt solution is slowly hydrolyzed into hydrated titanium dioxide and uniformly deposited on the surface of the aluminum powder, when the TiCl ₄ solution When adding 100ml, the pigment presents a strong silver interference color, stop adding the titanium solution and lye, continue to stir for 40min, and then stop the reaction. The pigment is filtered, washed until neutral, and dried at about 110°C. Put the dried aluminum powder pigment in a calcination furnace, pass nitrogen gas, slowly raise the temperature from room temperature to 600°C±20°C, and roast at this temperature for 30 minutes to obtain silver pearlescent aluminum powder pigment.

Example 5

Add 10g of silicon-coated aluminum powder pigment with a diameter of 10-100μm into the reaction vessel, add 100g of water, and stir well to form an aluminum powder suspension. Adjust the pH value of the suspension to 1.8 ± 0.3, slowly raise the temperature of the suspension to 70 °C ± 5 °C, and slowly add _the TiCl solution to the suspension at a rate of 1.0 ml/min under stirring conditions ( _the content of TiCl is 100g/L), and drop NaOH aqueous solution (NaOH content is 50g/L) at the same time, in order to keep the pH value of the suspension stable, so that the titanium salt solution is slowly hydrolyzed into hydrated titanium dioxide and uniformly deposited on the surface of the aluminum powder, when the TiCl ₄ solution When adding 80ml, the pigment presents a golden interference color, stop adding the titanium solution and lye, and continue to stir for 50 minutes to stop the reaction. The pigment is filtered, washed until neutral, and dried at about 120°C. Put the dried aluminum powder pigment in a calcination furnace, pass in argon gas, slowly raise the temperature from room temperature to 500°C±20°C, and roast at this temperature for 60 minutes to obtain a golden pearlescent aluminum powder pigment.

Claims (7)

1. A pearlescent illusion aluminum powder pigment is characterized in that this kind of pigment is coated with one layer or alternately coated with nano-titanium dioxide or other metal oxide films with high refractive index on the surface of the flake aluminum powder base material. production. 2. The pearlescent illusion aluminum powder pigment according to claim 1, characterized in that the base material for preparing the pearlescent illusion pigment is the flake aluminum powder with acid-resistant properties coated with a transparent silicon dioxide film on the surface. 3. The pearly luster aluminum powder pigment according to claim 1, characterized in that the average particle size of the flaky aluminum powder substrate for preparing the pearly luster magic aluminum powder pigment is 10 μm˜150 μm. 4. A preparation method of the pearlescent illusion aluminum powder pigment as claimed in claim 1, characterized in that the nano-titanium dioxide film coating process: in the container, the surface is coated with a transparent silicon dioxide film with acid resistance Flake aluminum powder and ion-free water form a 5-10% suspension dispersion aqueous solution, adjust the pH of the solution to 1.5-2.5±0.3, heat the solution to 60°C-80°C, slowly add the titanium salt solution, and at the same time drop the lye to Keep the pH value of the solution stable, slowly hydrolyze the titanium salt into hydrated titanium dioxide and evenly deposit on the aluminum powder substrate, stop feeding when the set color is reached, keep stirring and reacting for 0.5~1.0h at the same temperature, filter the pigment, and use Wash with ionized water until neutral, filter, and dry at 100-120°C. 5. Put the above-mentioned dried pigment into a roasting furnace, and under the protection of an inert gas, roast the pigment at 500°C~600°C for 0.5~1.0h and then take it out to obtain the pearlescent magic aluminum as claimed in claim 1 powder paint. 6. The preparation method of the pearlescent illusion aluminum powder pigment according to claim 4, characterized in that the titanium salt solution used for depositing titanium oxide on the aluminum powder substrate is prepared from titanium tetrachloride. 7. The preparation method of the pearlescent magic color aluminum powder pigment according to claim 4, characterized in that the inert gas introduced during calcination is nitrogen or argon.