WO2019047387A1 - Tungsten oxide-mica photochromic pearlescent pigment and preparation method for dispersion liquid thereof - Google Patents

Abstract

Disclosed in the present invention are a tungsten oxide-mica photochromic pearlescent pigment and a preparation method for a dispersion liquid thereof, belonging to the field of preparation of novel functional materials. In the present invention, in order to overcome the deficiencies of the prior art, tungsten oxide is uniformly coated on the surface of the mica by means of the assistance of a water-soluble organic material and the adjustment of the pH, thereby preparing a tungsten oxide-mica photochromic pearlescent pigment. The obtained powder or a dispersion liquid thereof is directly exposed to ultraviolet light for different lengths of time to observe photochromic effects, and it is found that the prepared powder and dispersion liquid both exhibit good photochromic effects under ultraviolet light irradiation, the light response speed and photochromic reversibility being good. The method in the present invention is a low temperature chemical synthesis method, being mild, simple, efficient, and easy to industrialize.

Description

Method for preparing tungsten oxide-mica photochromic pearlescent pigment and dispersion thereof Technical field

The invention belongs to the field of preparation of novel functional materials, and relates to a preparation method and application of a tungsten oxide-mica photochromic pearlescent pigment and a dispersion thereof.

Background technique

Pearlescent pigment, as a pigment composed of a thin layer of metal oxide coated mica, has been widely used in architectural decoration, ink, automotive paint and textile printing because of its excellent chemical and high temperature resistance. Pearlescent pigments (MO _x - mica: MO _x usually refers to transition metal oxides) have the advantages of good stability and long service life, which can greatly increase the added value of ordinary transition metal oxides. The magical color and diverse functions of MO _x - mica based pigment pearlescent pigments provide a new color system and color quality, and have a huge market share worldwide. Up to now, pearlescent pigments which have been matured have titanium oxide (TiO ₂ )/tin oxide (SnO ₂ )/iron oxide (Fe ₂ O ₃ )-mica pearlescent pigments.

At present, tungsten oxide photoluminescent materials generally have problems such as slow light response, low photochromic efficiency, poor reversibility, and the necessity of relying on ultraviolet light sources, which greatly affects their practical application prospects. In order to further improve the optical properties (reflectance, absorption, scattering, etc.) of mica-based pearlescent pigments, the choice of oxides complexed with mica is critical. Due to its low toxicity, high reactivity and good resistance to photo-corrosion, tungsten oxide has been widely used in the fields of catalysis and optical and electrical devices, such as photocatalysts, gas sensing and smart windows. More importantly, due to its excellent coloring effect, tungsten oxide is one of the most widely used color developing materials. It can be applied not only to electrochromic devices, but also to gaschromic and photochromic devices. In addition, due to its excellent physical and chemical properties, tungsten oxide is widely used in the fields of catalysis, sensing and optoelectronics, such as water decomposition, catalytic degradation of pollutants, supercapacitors, electrochromic devices and the like.

However, there are few reports on tungsten oxide-mica photochromic pearlescent pigments. So far, there has been no report on the growth of tungsten oxide structure on the surface of micron-sized mica and the study of its photochromic effect.

Summary of the invention

In order to solve the deficiencies in the prior art tungsten oxide photoluminescent materials, the present invention provides a method for preparing a tungsten oxide-mica photochromic pearlescent pigment. The invention adopts low temperature chemical synthesis method to uniformly and completely coat tungsten oxide on the surface of the micron-sized mica substrate to obtain a tungsten oxide-mica powder material, and the powder material is further dispersed in the aqueous solution to obtain a tungsten oxide-mica dispersion liquid. The preparation method of the invention is simple and controllable, easy to enlarge, and industrially feasible, and the prepared pigment can achieve high-efficiency, rapid and reversible photochromic effect under ultraviolet light irradiation.

The present invention achieves the above technical effects by the following technical solutions:

The invention provides a preparation method of a tungsten oxide-mica photochromic pearlescent pigment, which comprises the following steps:

1) Weigh the soluble tungstate and add it to deionized water, and stir it at 400-1500 rpm for 50-70 minutes to obtain an aqueous solution of tungstate. The molar concentration of the aqueous solution of the tungstate is 0.001. -1.0M;

2) adding a micron-sized mica substrate to an aqueous solution of tungstate, stirring at 400-1500 rpm for 25-35 minutes to obtain a suspension A, the molar concentration of the mica substrate in suspension A 0.001-1.0M;

3) Weighing the water-soluble organic substance into the suspension A, stirring at 400-800 rpm for 2-26 hours to obtain a suspension B, the molar of the water-soluble organic substance in the suspension B The concentration is 0.005-0.100M;

4) slowly adding inorganic acid to the suspension B while stirring, adjusting the pH of the suspension B to 0.1-2; stirring at 400-800 rpm for 4 hours to obtain a suspension C, The molar concentration of the inorganic acid in the suspension C is 0.010-5.0M;

5) After the reaction is completed, the suspension C is centrifuged for solid-liquid separation, the lower layer solid is collected and added to the alcohol for ultrasonic cleaning, and the lower layer solid is collected by centrifugation, and the above operation is repeated 3-5 times; ultrasonic cleaning is performed using deionized water. The lower layer solid is collected by centrifugation and the product is dried in a constant temperature environment to obtain a tungsten oxide-mica photochromic pearlescent pigment.

The soluble tungstate described in the above production method is any salt containing a tungsten element. Preferably, the soluble tungstate is one of sodium tungstate and ammonium tungstate.

After obtaining the aqueous solution of the tungstate in the above preparation method, the method further comprises the step of adding a doping element to the aqueous solution of the tungstate; preferably, the doping element is in the element of zirconium, aluminum, copper, titanium, molybdenum or lithium. One or more; the method of adding a doping element is to directly add an aqueous solution prepared by doping elemental salts in an aqueous solution of a tungstate, the substance of the doping element The amount is 0.1-20% of the amount of the tungsten element; the addition of the doping element can change the response range of the photochromic light of the tungsten oxide, improve the light responsivity and the reversibility of the photochromism, so that the composite powder has more Good photochromic effect.

In the above preparation method, the micron-sized mica substrate in the step 2) is a mica substrate or an oxide-modified mica substrate, preferably a titanium oxide-modified mica substrate.

In the above preparation method, the water-soluble organic substance in the step 3) is polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA), polyethylene glycol (PEG), cetyltrimethylammonium bromide (CTAB). Or one, two or more of sodium dodecylbenzene sulfonate (SDBS).

In the above preparation method, the inorganic acid in the step 4) is one or more of hydrochloric acid, nitric acid or sulfuric acid; in the case of hydrochloric acid, the acid is an acid obtained by diluting concentrated hydrochloric acid with deionized water. The concentration of concentrated hydrochloric acid is 20-38%; the concentration of the acid obtained after dilution of the concentrated hydrochloric acid is 0.5-5 M, and the final concentration of the hydrochloric acid in suspension C is 0.010-5.0 M.

In the above preparation method, the acid diluted in the deionized water in the step 4) is added in a slow manner, and the total dropping time is not less than 30 minutes;

A method for preparing a tungsten oxide-titanium oxide modified mica photochromic pearlescent pigment dispersion, which comprises the following steps:

The tungsten oxide-mica photochromic pearlescent pigment is added to an aqueous solution of polyvinylpyrrolidone having a mass percentage of 1-10% by weight, and stirred at 400-2500 rpm until uniformly dispersed, and the obtained viscous solution is A dispersion of tungsten oxide-mica photochromic pearlescent pigment which can be used as a slurry for a subsequent coating process. Preferably, the polyvinylpyrrolidone has a molecular weight of between 5,000 and 360,000;

The invention also claims an application in which the above-described tungsten oxide-mica photochromic pearlescent pigment is used in the preparation of photochromic luminescent pigments. The photochromic effect of the tungsten oxide-mica powder material obtained by the invention is excellent, and the photochromic reaction is exhibited within a few minutes of irradiation of the ultraviolet lamp, which is far superior to the conventional tungsten oxide powder. At the same time, the photochromism is reversible, and the original color can be restored within a short time (minutes to tens of minutes) after evacuating the ultraviolet lamp.

The photochromic effect was observed by directly irradiating the tungsten oxide-titanium oxide-modified mica powder or the tungsten oxide-titanium oxide modified mica aqueous dispersion under ultraviolet light for different times, and the fading process was observed as tungsten oxide- The titanium oxide modified mica powder or the tungsten oxide-titanium oxide modified mica dispersion is evacuated from the ultraviolet lamp, and the reversibility of the photochromic process is achieved by repeating the process of ultraviolet lamp irradiation, evacuation, and irradiation. Wherein the ultraviolet lamp irradiation time is 1-60 minutes, preferably 3-30 minutes;

The invention provides a method for preparing a tungsten oxide-mica photochromic pearlescent pigment and a dispersion thereof, and a method for preparing a tungsten oxide-mica powder obtained by the preparation method, which is multifunctionalized by tungsten oxide Characteristic, the tungsten oxide-mica powder material prepared by the invention can be used as a multifunctional material in other fields such as catalysis, gas sensing, and optoelectronic applications.

The invention not only realizes the successful coating of tungsten oxide on the surface of mica by adding a water-soluble polymer, but also the addition of the water-soluble polymer makes the composite product have a good photochromic effect. Efficient, fast, and reversible photochromism is achieved under UV light. The present invention has the following innovations and advantages over the prior art:

1. The present invention combines a photochromic material with a conventional pigment to finally synthesize and prepare a micron-sized tungsten oxide-mica photochromic pearlescent pigment, and based thereon, prepares a dispersion which can be applied to different application surfaces.

2. In the raw material of the tungsten oxide-mica powder product prepared by the invention, the mica has good stability and low price, and the combination of tungsten oxide and mica increases the added value of the traditional pigment, and is also the application of the tungsten oxide photochromic material. Providing a good carrier, the commercialization prospects are clear.

3. The addition of the water-soluble polymer in the preparation method of the invention not only ensures the complete coating of the tungsten oxide on the surface of the mica, but also plays a key role in improving the photochromic effect of the composite.

4. The preparation method of the tungsten oxide-mica composite powder of the invention adopts the wet chemical synthesis method, and is completed at room temperature throughout the whole process, avoiding complicated equipment and high energy consumption cost, mild reaction condition, convenient operation and suitable for Industrial production.

5. The preparation method adopted by the invention can completely encapsulate tungsten oxide on the micron-sized mica substrate, and the obtained tungsten oxide-mica composite powder has excellent photochromic effect, and is presented within a few minutes of ultraviolet lamp irradiation. The photochromic reaction is much better than the traditional tungsten oxide powder. At the same time, photochromic reversibility is good, and the original color can be restored in a short time after evacuating the ultraviolet lamp.

DRAWINGS

Figure 1 is a scanning electron micrograph of a tungsten oxide-titanium oxide modified mica photochromic pearlescent pigment: the left image is a high resolution multiple of the tungsten oxide particles coated on the mica plate, and the right image is a low resolution multiple coated on the mica. Photograph of tungsten oxide particles on the sheet.

2 is an elemental analysis diagram of a tungsten oxide-titanium oxide modified mica photochromic pearlescent pigment.

Figure 3 is a photochromic diagram of a tungsten oxide-titanium oxide modified mica photochromic pearlescent pigment under ultraviolet light illumination.

4 is a photochromic effect diagram of a dispersion prepared from a tungsten oxide-titanium oxide modified mica photochromic pearlescent pigment.

Figure 5 is a photochromic effect diagram of a zirconium-doped tungsten oxide-titanium oxide modified mica photochromic pearlescent pigment.

Detailed ways

The invention is further illustrated by the following figures and specific examples, which are intended to illustrate the invention and not to limit the scope of the invention, and in any way limit the scope of the invention. The technical solutions obtained by modifying or replacing the present invention by those skilled in the art without any creative labor are all included in the patent protection scope of the present invention.

Experimental Example 1 Preparation of Tungsten Oxide-Titanium Oxide Modified Mica Photochromic Pearlescent Pigment and Dispersion of the Invention

1.1 Preparation of tungsten oxide-titanium oxide modified mica photochromic pearlescent pigment

0.5 g of sodium tungstate was added to 30 ml of deionized water, and stirred at 1000 rpm for 1-3 hours until the sodium tungstate was completely dissolved to obtain a solution. 0.6 g of the titanium oxide-coated mica substrate was weighed into the solution, and after stirring at 1000 rpm for 30 minutes, the suspension A was obtained, and 0.15 g of PVP (polyvinylpyrrolidone) was added thereto at 800 rpm. After stirring for 24 hours, a suspension B was obtained. The concentrated hydrochloric acid having a concentration of 30% was diluted with deionized water to 2 M, and 3 ml of 2 M hydrochloric acid was slowly added to the suspension B for 1 hour, and finally the reaction was further stirred at room temperature for 1-6 hours. After the reaction, the solution was separated by a centrifuge, the lower solid was collected, and ultrasonically washed with 40 ml of alcohol and centrifuged. After each centrifugation, the lower solid was collected, and the procedure was repeated 5 times, then ultrasonically washed once with deionized water and collected by centrifugation. The lower layer of solid is then dried in a constant temperature oven at 60 ° C to obtain a tungsten oxide-titanium oxide modified mica photochromic pearlescent pigment.

1.2 Preparation of tungsten oxide-titanium oxide coated mica photochromic pearlescent pigment dispersion

3 g of PVP (molecular weight: 50,000) was added to 50 ml of water, and after stirring for 30 minutes, 0.5 g of tungsten oxide-titanium oxide-mica photochromic pearlescent pigment was weighed and stirring was continued for 3 hours to obtain a uniform dispersion, which was used.

1.3 Photochromism of tungsten oxide-titanium oxide coated mica pearlescent pigment

The tungsten oxide-mica photochromic pearlescent pigment obtained by the above preparation method is characterized by X-ray diffraction and elemental analysis means. Fig. 1 is a scanning electron micrograph of a tungsten oxide-titanium oxide-modified mica photochromic pearlescent pigment of the present invention; it can be seen from the figure that tungsten oxide-titanium oxide is well coated on the surface of the mica substrate.

Figure 2 is an elemental analysis diagram of a tungsten oxide-titanium oxide modified mica photochromic pearlescent pigment of the present invention. It can be seen from the spectrum that the photochromic pearlescent pigment has a Ti content of 25.85% and a W element content of 6.85%, indicating the coating of the tungsten oxide-titanium oxide on the mica substrate.

The optical absorption characteristics of the powder were analyzed by ultraviolet-visible spectroscopy. Scanning electron micrographs were used to investigate the growth of tungsten oxide on the surface of mica. The tungsten oxide-titanium oxide modified mica composite powder was observed under a UV lamp for 3 minutes, and then the color change was observed. Then, the color change was recorded, and after leaving the ultraviolet lamp, it was allowed to stand at room temperature for 1 minute to 24 hours, and the color change was recorded. After the color is completely changed, the ultraviolet lamp is repeatedly irradiated to observe the color change. Figure 3 is a photochromic effect of the tungsten oxide-titanium oxide modified mica photochromic pearlescent pigment of the present invention under ultraviolet light irradiation. It can be seen from the figure that the tungsten oxide-titanium oxide-modified mica photochromic pearlescent pigment is initially pale yellow, and after darkening for 3 minutes by ultraviolet light, it exhibits a deep blue color, and the pigment is substantially recovered after 16 hours of removal of the ultraviolet lamp. To the initial color.

The slurry prepared by the tungsten oxide-titanium oxide modified mica photochromic pearlescent pigment was observed under a UV lamp for 10 seconds to 3 minutes, and the color change was observed. The color change was taken out, and the ultraviolet lamp was irradiated and then left at room temperature. Record the color change for 30 minutes. After the color is completely changed, the ultraviolet lamp is repeatedly irradiated to observe the color change. 4 is a photochromic effect of a dispersion prepared by the tungsten oxide-titanium oxide-modified mica photochromic pearlescent pigment of the present invention under ultraviolet light irradiation. The dispersion exhibited a better photochromic effect under UV light. The initial color of the dispersion is light yellow turbid liquid, which appears bright blue after 10 seconds of UV light irradiation. Then, after removing the UV lamp for 1 minute, most of the blue color has receded. After 5 minutes, the blue color completely recedes and recovers. To the initial color.

Experimental Example 2 Preparation of Zirconium Ion Doped Tungsten Oxide-Titanium Oxide Modified Mica Photochromic Pearlescent Pigment and Dispersion of the Invention

Preparation of zirconium-doped tungsten oxide-titanium oxide modified mica photochromic pearlescent pigment

0.7 g of sodium tungstate and 0.005 g of zirconium chloride were added to 30 ml of deionized water, and stirred at 1000 rpm for 1 hour until the sodium tungstate and zirconium chloride were completely dissolved to obtain a solution. Weigh 0.8g of titanium oxide coated mica substrate into the solution at 1000 rpm / After stirring for 30 minutes, the suspension A was obtained, 0.10 g of PVP was added thereto, and the mixture was stirred at 800 rpm for 24 hours to obtain a suspension B. To the suspension B, 4 ml of 2 M hydrochloric acid was added dropwise over 1 hour, and then the reaction was further stirred at normal temperature for 3 hours. After the reaction was completed, the solution was layered by a centrifuge, the lower solid was collected, and ultrasonically washed and centrifuged with 40 ml of alcohol. After each centrifugation, the lower solid was collected, and the procedure was repeated 5 times, followed by ultrasonic cleaning with deionized water once and centrifugation. The lower solid was collected. The product was then dried in a constant temperature environment of 60 ° C for 2 hours.

Preparation of zirconium-doped tungsten oxide-titanium oxide modified mica photochromic pearlescent pigment dispersion

2 g of PVP (molecular weight: 360,000) was added to 50 ml of water, and after stirring for 30 minutes, 0.3 g of zirconium-doped tungsten oxide-titanium oxide-mica composite powder was weighed and stirred for 3 hours to obtain a uniform dispersion, which was used.

2.3 Photochromic effect of zirconium-doped tungsten oxide-titanium oxide modified mica photochromic pearlescent pigments and dispersions

The zirconium-doped tungsten oxide-titanium oxide-modified mica photochromic pearlescent pigment was observed under a UV lamp for 3 minutes, and the color change was observed. The results are shown in Fig. 5. After leaving the UV lamp, it was allowed to stand at room temperature for 1 minute to 24 hours, and the color change was recorded. After the color is completely changed, the ultraviolet lamp is repeatedly irradiated to observe the color change. Figure 5 is a photochromic effect of the zirconium-doped tungsten oxide-titanium oxide modified mica photochromic pearlescent pigment of the present invention under ultraviolet light irradiation. The initial color of the prepared powder was light yellow, and it appeared dark blue after 3 minutes under UV light. Compared with the undoped sample, the color change of the zirconium-doped sample was more significant, highlighting the ion doping pair. The effect of the photochromic effect of the sample.

The dispersion prepared by zirconium-doped tungsten oxide-titanium oxide modified mica photochromic pearlescent pigment was observed under a UV lamp for 10 seconds to 3 minutes, and the color change was observed, and the color change was taken out, and the ultraviolet light was irradiated at room temperature. Place it for 1-30 minutes and record the color change. After the color is completely changed, the ultraviolet lamp is repeatedly irradiated to observe the color change. Its color change is close to Figure 4.

Claims (10)

1. A method for preparing a tungsten oxide-mica photochromic pearlescent pigment, which comprises the following steps:

   1) Weigh the soluble tungstate and add it to deionized water, and stir it at 400-1500 rpm for 50-70 minutes to obtain an aqueous solution of tungstate. The molar concentration of the aqueous solution of the tungstate is 0.001. -1.0M;

   2) adding a micron-sized mica substrate to an aqueous solution of tungstate, stirring at 400-1500 rpm for 25-35 minutes to obtain a suspension A, the molar concentration of the mica substrate in suspension A 0.001-1.0M;

   3) Weighing the water-soluble organic substance into the suspension A, stirring at 400-800 rpm for 2-26 hours to obtain a suspension B, the molar of the water-soluble organic substance in the suspension B The concentration is 0.005-0.100M;

   4) slowly adding inorganic acid to the suspension B while stirring, adjusting the pH of the suspension B to 0.1-2; stirring at 400-800 rpm for 4 hours to obtain a suspension C, The molar concentration of the inorganic acid in the suspension C is 0.010-5.0M;

   5) After the reaction is completed, the suspension C is centrifuged for solid-liquid separation, the lower layer solid is collected and added to the alcohol for ultrasonic cleaning, and the lower layer solid is collected by centrifugation, and the above operation is repeated 3-5 times; ultrasonic cleaning is performed using deionized water. The lower layer solid is collected by centrifugation and the product is dried in a constant temperature environment to obtain a tungsten oxide-mica photochromic pearlescent pigment.
2. The method for preparing a tungsten oxide-mica photochromic pearlescent pigment according to claim 1, wherein the soluble tungstate is one or more of sodium tungstate and ammonium tungstate.
3. The method for preparing a tungsten oxide-mica photochromic pearlescent pigment according to claim 1, further comprising the step of adding a doping element to the aqueous solution of the tungstate after preparing the aqueous solution of the tungstate, The doping element is one or more of zirconium, aluminum, copper, titanium, molybdenum or lithium.
4. The method for preparing a tungsten oxide-mica composite powder according to claim 3, wherein the method of adding a doping element is an aqueous solution prepared by directly adding a doping element salt to an aqueous solution of a tungstate, The amount of the substance of the doping element is 0.1-20% of the amount of the tungsten element substance.
5. The method for preparing a tungsten oxide-mica photochromic pearlescent pigment according to claim 1, wherein the micron-sized mica substrate is a mica substrate or an oxide-modified mica substrate, preferably a titanium oxide-modified mica substrate. .
6. The method for preparing a tungsten oxide-mica photochromic pearlescent pigment according to claim 1, wherein the water-soluble organic substance is polyvinylpyrrolidone, polyvinyl alcohol, polyethylene glycol, hexadecyltrimethyl One or more of ammonium bromide or sodium dodecylbenzene sulfonate.
7. The method for producing a tungsten oxide-mica photochromic pearlescent pigment according to claim 1, wherein the inorganic acid is one or more of hydrochloric acid, nitric acid or sulfuric acid.
8. A method for preparing a tungsten oxide-titanium oxide modified mica photochromic pearlescent pigment dispersion, characterized in that it comprises the following steps:

   The tungsten oxide-titanium oxide modified mica photochromic pearlescent pigment prepared by the preparation method according to claim 5 is added to an aqueous solution of polyvinylpyrrolidone having a mass percentage of 1-10% by weight, at 400-2500 rpm. The mixture was stirred until uniformly dispersed, and the obtained viscous solution was a tungsten oxide-titanium oxide-modified mica photochromic pearlescent pigment dispersion.
9. The method for preparing a tungsten oxide-titanium oxide-modified mica photochromic pearlescent pigment dispersion according to claim 8, wherein the polyvinylpyrrolidone has a molecular weight of from 5,000 to 360,000.
10. Use of the tungsten oxide-mica photochromic pearlescent pigment of claim 1 for the preparation of a photochromic luminescent pigment.

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