The pearlescent pigment is a kind of optical effect pigment because it can show a certain metallic luster, so it is also called a non-metallic pigment with a metallic luster. Pearlescent pigments have the flashing effect of metallic pigments and can produce the soft color of natural pearls. When exposed to sunlight, they can produce multi-level reflections. The reflected light interacts to present soft or colorful luster and colors.
It can be widely used in many fields such as coatings, plastics, rubber, inks, papers, textiles, cosmetics, decorations, handicrafts, leather, enamel, ceramics, packaging supplies, printing decoration, and building materials.
1.basic introduction
Pearlescent pigments are the most important colorants for beauty cosmetics for the face, lips, eyes, and nails. The use of pearlescent pigments has expanded from classic color cosmetics to personal care products, including skin and hair care products, and provides unique aesthetic effects.
Pearlescent pigments are composed of substances with a higher refractive index, which acts as an interference filter in an environmental medium with a low refractive index. These filters divide the incident light that arrives at the interface between materials with different refractive indices at a suitable angle into reflected light and transmitted light of complementary colors (incident light at other angles can also be absorbed and reflected). This effect is the same phenomenon we observe in our daily life, such as soap bubbles, spilled oil, and the color of pearls.
The pearlescent pigment is a layered system consisting of a substrate and a covering layer. The substrate is generally natural muscovite, silica, or aluminum flakes; the covering layer is titanium dioxide or iron oxide, CI 77510 (pigment blue 27, ferric ferrocyanide), or carmine, etc. The substrate must be lamellar, flexible, and relatively smooth. The thickness and refractive index of the metal oxide determine the interference effect.
2.nature
The excellent chemical corrosion resistance and high-temperature resistance of pearlescent pigments make it possible to be widely used in coatings, inks, plastics, and various fields. They provide these products with a new color system and color quality. Pearlescent pigments have low heavy metal content and meet relevant safety technical standards, so they can be used in food packaging and children's toys. Neither acid nor alkali can corrode pearlescent pigments at room temperature. Pearlescent pigments are non-flammable, non-spontaneous, non-conductive, and can withstand high temperatures of 600~800°C. Pearlescent pigments can also be used in reactive coatings for radiation curing systems (electron beam curing, light curing). The special surface chemical structure of pearlescent pigments makes it have excellent hydrophilicity, so it can be applied to water-based coatings, but its lipophilicity is poor, so when it is used in organic systems, there will be a problem of poor dispersion, and surface treatment of pearlescent pigments is required, so that it can also be well applied in organic systems.
3.basic classification
Pearlescent pigments are mainly divided into the following categories:
(1)Inorganic base pearlescent pigment
Inorganic substrate pearlescent pigments mainly include high mercury chloride, basic lead carbonate, acid lead arsenate, acid lead phosphate, and bismuth hydroxide. However, such pearlescent pigments are either potentially toxic or have poor chemical stability, which greatly limits their application range.
(2)Mica base pearlescent pigment
Natural mica is an excellent substrate for preparing mica pearlescent pigments and is widely used because of its abundant resources and low manufacturing cost.
Mica titanium pearlescent pigment is a kind of pearlescent pigment with the most extensive research and the most mature technology. Due to the difference in refractive index between titanium dioxide and mica substrate, better pearl effect, color effect, and chromatic effect of viewing angle are produced through multiple reflections and interference of light.
(3)other
With the continuous deepening of the research on pearlescent pigments, some other matrix materials have also been discovered and used in the preparation process of pearlescent pigments, such as glass-based pearlescent pigments, aluminum flake-based pearlescent pigments, oxide-based pearlescent pigments, kaolin, ceramics, etc. flakes, graphite flakes, etc.
4.application
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Textiles
Combining pearlescent pigments with textiles can make the fabrics have excellent pearl luster and color. Adding pearlescent pigments to the printing paste, printing on textiles, and post-processing can make the fabrics produce strong pearl-like luster from various angles under sunlight or other light sources.
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Paint
Coatings are widely used, whether it is automotive topcoats, auto parts, building materials, household appliances, etc., and will be used for color modification and to achieve a certain protective effect.
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Ink
Pearlescent ink is widely used in high-end packaging and printing, such as cigarette packs, high-end wine labels, anti-counterfeiting printing, and other fields.
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Ceramics
Applying pearlescent pigments to ceramics can make ceramics have unique optical properties.
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Plastic
Mica titanium pearlescent pigment is suitable for almost all thermoplastic and thermosetting plastics, it will not cause fading or graying of plastic products and can produce bright metallic luster and pearlescent effect.
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Cosmetics
The variety, performance, and color diversity of cosmetics depend on the diversity of the pigments they use. Pearlescent pigments are widely used as cosmetic pigments because of their strong hiding power or high transparency, good hue, and wide color spectrum.
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Other
Pearlescent pigments are also widely used in other production and daily life. Such as the imitation of bronze appearance, the application of artificial stone, etc.