Research progress of the most popular colored mica

Research progress of colored mica titanium pearlescent pigments at home and abroad

Rong Jianfeng, Lang Jianfeng (College of chemical engineering and biotechnology, Hebei University of technology, Tangshan 063009, Hebei)

Jia Qianyi (College of materials, Hebei University of technology, Tangshan 063009, Hebei)

Abstract: This paper summarizes the new progress in the development and research of colored mica titanium pearlescent pigments at home and abroad in recent years; It is pointed out that broadening the chromatographic range of colored pearlescent pigments and developing flake conductive pearlescent pigments will be the research and development direction in the future

key words: colored mica pearlescent pigment; Rare earth oxide; Functional material

pearlescent pigment refers to the decorative pigment with pearl luster. Mica titanium pearlescent pigment is composed of mica as the matrix and coated with a layer of high refractive index TiO2 and other metal oxide transparent film on its surface. It is widely used in coating, decoration, cosmetics, printing ink, ceramics and other industries

mica titanium pearlescent pigments can be roughly divided into three categories: silver white, rainbow and coloring. Silver white pearlescent pigments can only show a single silver white phase because white light is reflected on the surface of mica titanium and has no transmission light. However, due to the different particle size of mica and TiO2 coverage rate, they will show pearl like mercerization changes with different visual angles. It is the most versatile pearlescent pigment, but its hiding power is poor. Rainbow type is an optical film evenly coated with TiO2 or other metal oxides with high optical refractive index, such as Fe2O3, Cr2O3, SnO2, etc. on the sheet mica matrix, which produces excellent pearlescent effect and heterochromatic effect with angle through the multi-level reflection and interference of light. Because this type of pigment can both reflect and transmit light, it can strengthen some wavelengths of light, while others will weaken, thus showing different hues. The biggest advantage of rainbow pearlescent pigments is that they can match colors like ordinary pigments, and the resulting multicolor is bright and gorgeous. Coloring type is to add coloring pigment or dye coating on the basis of silver white and rainbow pearlescent pigments. This kind of pigment can absorb some light in the visible spectrum. If the absorption color and the reflection color of oxide coated mica pigment have the same hue, the absorption color increases, and the color can be seen at all angles; If the hue is different, you can only see the reflected color at the mirror angle, and the color that absorbs the pigment at other angles. Between the above two extremes, a transition color can be seen. Pigmented pearlescent pigments are a kind of pigments with complete color spectrum and bright color by using the pearlescent luster of mica titanium and the optical properties of colored substances to absorb part of visible light

this paper briefly introduces the research and development of colored mica titanium pearlescent pigments at home and abroad in recent years

1 research and development status of colored mica titanium pearlescent pigments at home and abroad

1.1 research and development status abroad

colored mica titanium pearlescent pigments are generally coated with mica titanium pearlescent pigments as the matrix. According to the different coating, it can be roughly divided into two categories: (1) the inner coating is colorless and transparent metal oxide. The outer coating is the same or different single metal oxide or other non-metal oxide that can absorb different wavelengths of light; (2) The outer coating is a composite of various metal oxides

1.1.1 the outer coating is a single metal oxide or non-metal oxide

RCK company has developed a colored mica titanium pearlescent pigment with mica titanium as the substrate and coated with various non-ferrous metal oxides. For example, ferrous cyanide, Fe2O3, Fe3O4, -feooh, Cr2O3, Mn (OH) 2, etc. are used for coating. In addition, in order to improve the color and weather resistance of automotive topcoats, Merck has also successfully developed a new gray pearlescent pigment without carbon black coloring, which makes the fe2o3-tio2 coating on mica react chemically at high temperature to produce silver gray FeTiO3 or ferrotitanium spinel (fetio4); The black mica pearlescent pigment with metallic texture can be obtained by converting Fe2O3 in the mica titanium pearlescent pigment coated with iron oxide into black Fe3O4

the U.S. patent points out that the peeling, fading and other changes of pigments used outdoors due to long-term exposure to the external environment are the result of the combined action of ultraviolet light, moisture and temperature in the sun. In order to obtain good weather resistance, the mica was pretreated with tin solution, then plated with titanium, filtered, washed, and calcined to convert the crystal form of TiO2 into rutile. Finally, the pigment was post treated with Cr (OH) 3 solution. Compared with the previous pearlescent pigments, the weather resistance was significantly improved

because this kind of pearlescent pigment is not only coated with colorless transparent metal oxide film that plays an interference role to produce pearlescent, but also has colored metal oxide film, it has strong pearlescent luster, high hiding power, and a certain coloring power at the same time

1.1.2 the outer coating is a composite of a variety of metal oxides

with people's increasingly high-grade requirements for pearlescent pigments, relevant countries are actively exploring appropriate outer coating, striving to make the products have complete chromatography, excellent performance, low price and strong practicability. Korpit studied a pearlescent pigment. First, the TiO2 film with high refractive index was coated on the matrix mica. The calcined mica titanium was suspended in an aqueous solution containing zinc nitrate, cobalt nitrate, nickel chloride and urea, heated to a certain temperature, then the temperature was controlled in stages, and then the potential difference was used to coat it evenly and fully layer by layer to form a Co Ni Zn composite oxide film, which was filtered and dried to produce a high brightness green pearlescent pigment

Daidao et al. Coated the surface of mica titanium with Cr, Cu, Mn composite metal oxides to produce black pearlescent pigments. The specific method is: suspend mica titanium in an aqueous solution containing urea, sulfuric acid, soluble Cu, Cr, Mn salts, heat it at 70~100 ℃ for 3~4h, then filter, wash, dry, calcine and burn it. Another Japanese patent reported that the gold pearlescent pigment was prepared by coating the composite oxide of Co Ni sb on the surface of mica titanium

V clav? Tengl et al. Reported the preparation method of blue-green pearlescent pigment. The Muscovite with a particle size of 10~60 m is made into a suspension. Under the condition of stirring, under the condition of 95 ℃ and ph=1, the experimental force of the hydraulic system is loaded very unstable. Add a certain concentration of TiCl4 solution and CoCl2, MgCl2 and CaCl2 aqueous solutions. After stirring for a certain time, adjust the pH to 6 with NaOH. The precipitate is washed, dried and calcined to obtain the product

mailefj reported the preparation method of bright blue mica titanium pearlescent pigment: the water suspension of mica powder was treated with titanium oxysulfate and water to obtain TiO2 coated mica. Then it is suspended in water, mixed with cobalt nitrate, aluminum nitrate and urea, coated at 100 ℃, and the separated pigment is dried and calcined to produce the product

pearlescent pigments coated with a variety of metal oxides have higher hiding power and coloring ability, but the pearlescent effect is lower than that of the first kind

1.2 domestic development status

the research and development of mica titanium pearlescent pigment in China started later than that in Europe, America, Japan and other economically developed countries. Scientific research, production and application are in the primary stage of development, and the output, quality and application level of products are at a low level. Compared with foreign countries, the gap is mainly manifested in the low gloss of pigments, the color is not pure and bright enough, and the wettability and dispersibility are not ideal, resulting in the limitation of the scope of application of pigments. At present, domestic research work mainly focuses on the exploration of coating process, determining and improving various process factors and parameters that affect the quality of mica titanium pearlescent pigments, and exploring ways to improve the whiteness, color effect and pearlescent gloss of mica titanium pearlescent pigments

1.2.1 iron oxide coated mica titanium pearlescent pigment

there are many reports about iron oxide coated mica titanium in China, mainly focusing on the use of different coating processes, and this kind of colored pearlescent pigment is studied and explored. Hao Hong and others used boiling hydrolysis method to prepare iron oxide coated cloud electronic universal testing machine and tensile testing machine. The difference between universal and tensile mother titanium pearlescent pigments. The effects of different process conditions, such as pH value, deposition amount and reaction time, on the product quality were investigated. The optimum technological conditions are: pH 2~4, reaction time 1~1.5h, calcination temperature 670 ℃, different Fe2O3 deposition, different colors of pearlescent pigments can be obtained

Fu xiansong et al. Used mica titanium as the substrate, coated its surface with Fe2O3 by liquid-phase precipitation method, so as to prepare bronze pearlescent pigment. The optimum process parameters of the coating process and roasting process were studied, and the pigment properties were tested. The results are as follows: oil absorption is 30%, hiding power is 15.24g/m2, coloring power is 120.3% (800 ℃ sample is the standard sample), Munsell label hv/c is 5.0yr7.80/13.2

Zhang Xianjun et al. Studied the process of preparing colored pearlescent pigments by metal organic chemical vapor deposition (MOCVD). It uses Ti (OC2H5) 4 as the material source and high-purity nitrogen as the carrier gas in the presence of oxygen. When the deposition temperature is 300 ℃, the crystalline form of TiO2 film deposited is anatase. When the temperature rises to 500 ℃, the crystalline form of TiO2 film is rutile, and the coating is dense. On this basis, by controlling different coating time, and then coating iron oxide dominated by Fe2O3, colored pearlescent pigments with soft luster such as orange red and golden red can be obtained

1.2.2 mica titanium pearlescent pigment coated with other metal oxides and non-metal oxides

further multi-layer metal coating treatment or repeated coating of mica titanium can enrich the coating phase of mica titanium products, improve their weather resistance, water resistance, dispersion or add other functions

ZHONG Shengwen et al. Studied the composite coloring of cobalt oxide, cobalt oxide alumina and chromium oxide tin oxide respectively. It is found that the primary coating test result of divalent cobalt is dark light blue, and it is black after adding oxidant; Alumina cobalt oxide composite coating is light blue-green; The chromium oxide tin oxide composite coating is yellow. The change of its color also depends on the coating amount of the colorant

houwenxiang et al. Used mica titanium as the substrate, added phthalocyanine blue activated carbon in the liquid phase, so that phthalocyanine blue and activated carbon were coated on the surface of mica titanium, so as to prepare pearlescent pigments with blue to blue black appearance

Chen Jing et al. Prepared cobalt blue mica pearlescent pigment by microemulsion method. Co2+ and al3+ were dissolved in oleic acid/n-butanol/sodium carbonate aqueous solution and oleic acid/sodium hydroxide aqueous solution respectively to make micro lotion, and then the two kinds of micro lotion were mixed to produce nano cobalt blue precursor. Add the reaction solution into the reaction vessel containing water filled wet mica to improve the competitiveness and effectiveness of the real economy, stir the reaction for 30min while adding, and then filter, wash, dry and calcine the reaction product to prepare cobalt blue mica pearlescent pigment. The test results show that the prepared pigment is spinel type, and the particle size of cobalt blue is 10~30nm, which is spherical, uniformly and densely coated on the surface of mica matrix

Shen lazhen and others used urea as precipitant to prepare light gray nanocomposite mica titanium conductive pearlescent pigments by homogeneous precipitation method. The relationship between different reaction substrates, substrate feeding methods and other process parameters and the conductivity and pearlescent effect of pigments was studied

Du Haiyan, Chen Qirong and others used mica titanium with interference color as the substrate, colored with chromium oxide and cobalt oxide films respectively, and prepared mica titanium pearlescent pigments with the function of heterochromaticity with angle. The influence of experimental conditions on the effect of pigment color changing with color was investigated, and the angle change was analyzed