Mica Pigments Research Articles

Dot Off Dot Screen Printing with RGBW Reflective Inks

Recent advances in pigment production resulted in the possibility to print with RGBW primaries instead of CMYK and performing additive color mixing in printing. The RGBW pigments studied in this work have the properties of structural colors, as the primary colors are a result of interference in a thin film coating of mica pigments. In this work, we investigate the angle-dependent gamut of RGBW primaries. We have elucidated optimal angles of illumination and observation for each primary ink and found the optimal angle of observation under diffuse illumination. We investigated dot off dot halftoned screen printing with RGBW inks on black paper and in terms of angle-dependent dot gain. Based on our observations, optimal viewing condition for the given RGBW inks is in a direction of around 30∘ to the surface normal. Here, the appearance of the resulting halftoned prints can be estimated well by Neugebauer formula (weighted averaging of the individual reflected spectra). Despite the negative physical dot gain during the dot off dot printing, we observe angularly dependent positive optical dot gain for halftoned prints. Application of interference RGBW pigments in 2.5D and 3D printing is not fully explored due to the technological limitations. In this work, we provide colorimetric data for efficient application of the angle-dependent properties of such pigments in practical applications.

Facile preparation of anticorrosive and decorative multifunctional coatings via the inclusion of pearlescent oxide-covered mica pigments

Facile preparation of anticorrosive and decorative multifunctional coatings via the inclusion of pearlescent oxide-covered mica pigments

The electromagnetic wave absorption properties of woven glass fiber composites filled with Sb2O3 and SnO2 nanoparticles doped mica pigments

AbstractIn this study, the electromagnetic wave absorption properties of woven glass fiber reinforced epoxy composites with Sb2O3 and SnO2 nanoparticles doped mica pigments were investigated. Herein, we synthesized SnO2/mica, Sb2O3/mica, and Sb2O3:SnO2/mica pigments using the sol–gel method. Subsequently, mica pigments filled glass fiber/epoxy composite panels were fabricated with a vacuum assisted resin mold. The phase, crystal, and morphological examinations of particles confirm the deposition of SnO2 and Sb2O3 nanoparticles on the mica surfaces. The electromagnetic wave absorption properties of samples were measured using the S parameters and obtained dielectric data. Sb2O3:SnO2/mica particles display higher complex permittivity and dielectric loss values due to the strong interfacial polarization between conductive nano metal‐oxide shells and mica surfaces. According to the calculated reflection loss values, Sb2O3:SnO2/mica particles exhibit superior electromagnetic wave absorption performance with a minimum reflection loss of −25.62 dB for 2.4 mm thicknesses with effective bandwidth between 9.3 and 12.4 GHz. The S parameters of the prepared structural composites with the size of 30 cm × 30 cm × 3 mm was determined by the free‐space technique using the transmission line technique. According to the S12 parameters, filled glass fiber/epoxy composite containing 25 wt% Sb2O3:SnO2/mica show a minimum reflection loss of −20.426 dB at 8.2 GHz with effective bandwidth between 8.2 and 9.67 GHz. These results indicate that Sb2O3:SnO2/mica‐filled fiber/epoxy composite is an excellent candidate for the practical application of electromagnetic wave absorbers.

Pearlescent Mica-Doped Alginate as a Stable, Vibrant Medium for Two-Dimensional and Three-Dimensional Art.

Emergent technologies are driving forces in the development of innovative art media that progress the field of modern art. Recently, artists have capitalized on the versatility of a new technology to create, restore, and modify art: additive manufacturing or three-dimensional (3D) printing. Additively manufactured art relies heavily on plastic-based materials, which typically require high heat to induce melting for workability. The necessity for heat limits plastic media to dedicated 3D printers. In contrast, biologically derived polymers such as polysaccharides used to create “bioinks” often do not require heating the material for workability, broadening the types of techniques available for printing. Here, we detail the formulation of a bioink consisting of mica pigments suspended in alginate as a new, vibrant art medium for 2D and 3D compositions. The properties that make alginate an ideal colorant binder are detailed: low cost with wide availability, nontoxicity and biocompatibility, minimal color, and an array of attractive physicochemical properties that offer workability and processing into 2D and 3D structures. Further, the chemical composition, morphology, and dispersibility of an array of mica pigment additives are characterized in detail as they pertain to the quality of an art medium. Alginate-based media with eight mica colors were formulated, where mica addition resulted in vibrantly colored inks with moderate hiding power and coverage of substrates necessary for 2D printing with thin horizontal and vertical lines. The utility of the media is demonstrated via the generation of 2D and 3D vibrant structures.

Printing the light

AbstractThis paper explores the relationship between additive and subtractive mixing for colour printing. Using Spectraval mica pigments (Merck)—marketed as RGB pigments—colour is generated by selective reflection and prints are based on additive colour mixing principles, that when printed onto black paper, create white and a range of colours. Although currently used mostly for decorative effects, they can be the basis of additive 'process' inks, that present new opportunities for and challenges to traditional print markets. The viewing angle dependency of their selective reflection favours applications in security printing similar to the holograms on bank cards for example. Traditional measurement and modelling methods are difficult to apply due to the layering and irregular dispersion of pigments.

Colour Deceives Continually

This paper explores the relationship between additive and subtractive mixing for printing colour. Using mica pigments that are based on additive colour mixing principles, that when combined, create white. Although currently used for decorative effects for printing, can present a challenge to traditional print markets. We describe different plate making and printing methods for photographic and photomechanical processes, and discuss their applications and limitations.

Studies on the preparation and characterization of composite La-doped γ-Ce2S3-coated mica cool pigments

In this paper, a new series of γ-Ce2-xLaxS3/mica (X ranges from 0 to 0.8) pigments were synthesized by depositing La-doped γ-Ce2S3 pigments on mica to improve the color and optical properties of the pigments. XRD, SEM, TG, EDS, UV–VIS-NIR diffuse reflection spectrum and CIE-L* a* b* color scale were used to characterize the crystal structure, morphology, optical properties, thermal stability and color properties of γ-Ce2-xLaxS3/mica pigments. The results show that the cubic crystal structure of γ-Ce2-xLaxS3/mica pigments has been successfully prepared. In addition, the thermal stabilization temperature of γ-Ce1.6La0.4S3/mica pigment reaches 550 °C, and composite γ-Ce2-xLaxS3/mica pigments have excellent color stability and ultraviolet absorption ability. More importantly, the composite pigments also have higher NIR diffuse reflectance and solar reflectance than pure γ-Ce2S3; the NIR solar reflectance of γ-Ce1.6La0.4S3/mica pigment could be improved up to 89.64%. These excellent properties indicate that γ-Ce2-xLaxS3/mica pigments can be used as cool pigments in the near-infrared and ultraviolet ranges.

Influences of Cr content and heat treatment on the optical property of the green mica-nano Cr2O3 pearlescent pigment

In the present work, green nano Cr2O3-coated mica pigments were prepared by homogeneous precipitation. Structure, morphology, and optical properties were investigated by X-ray diffraction, thermogravimetric and differential thermal analysis, scanning electron microscopy, and colorimetric analysis. The results showed that an amorphous coating was synthesized and crystallized to Cr2O3 after heat treatment at 800°C. Average particle size of the coating was about 100 nm. The optical properties of the final pigment depended on the Cr content and heat-treatment temperature. The pearlescent index increased as chromium nitrate content increased and then decreased. Lower calcination temperature can cause lower L* value and pearlescent index.

Structural analysis and characterization of doped spinel Co2−xMxTiO4 (M=Mg2+, Mn2+, Ni2+, Cu2+ and Zn2+) coated mica composite pigments

A new kind of composite mica pigments were prepared by coating Co2−xMxTiO4 composite oxide nanoparticles onto mica, to investigate the effects of doping ions Mg2+, Mn2+, Ni2+, Cu2+ and Zn2+ on the properties of the doped composite pearlescent pigments, such as the crystal structure, color and shading power. The structure, morphology, color and shading power of the coated pigments were characterized by the X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–vis spectrophotometer and CIE L*a*b* methods. SEM images of coated pigments showed that mica were coated uniformly with a single layer of dispersed nanoparticles. Research of the doped composite pigments showed that the doping ions had entered into the spinel crystal structure, forming a new kind of composite mica pearlescent pigments coated with Co2−xMxTiO4. For the analysis of color and shading power of the pigments, doping of Ni2+ and Zn2+ can improve the color and shading power of the doped pigments, but the larger dosage of Zn2+ doping can weaken the color and shading power of the doped pigments. Doping of Mg2+, Mn2+ and Cu2+ metal ions can also weaken the color and shading power of the doped pigments.

Influence of rheology modifiers and coating parameters on the color-changing effects of textile coatings with multi-layered mica pigments

In order to optimize the color-changing effects of textile knife-coatings containing multi-layered mica pigments (effect pigments; EPs), the properties and structure of the coating formulation/layer during and after application were investigated. Three pigment coating formulations were prepared by first mixing the EP dispersion into a water-based polyurethane binder. Different types of rheology modifiers (RMs), liquid dispersion of sodium polyacrylates (LDPSAP), hydrophobically alkali swellable emulsions (HASEs) and hydrophobically modified ethoxylated polyurethane, were then added to the dispersion. The rheological behavior of the coating formulations was characterized in terms of the shear rate dependence of the viscosity. The formulations were applied onto the same type of textile substrate using a knife-coating technique. The choice of RM as well as variations in gap height and coating speed increased the solids deposit. The increased amount of coating deposits (thicker coating layers) corresponded to more and better dispersed EPs within the coated layer as well as more horizontally oriented platelets as confirmed by scanning electron microscopy. Multi-angle spectrophotometer measurements showed that the CIE L*a*b* color coordinates varied strongly depending on detection angle. The variations of the absolute values of L* and a* were more pronounced between –15° and 15° detection angles, corresponding to angles with the greatest visual color changes. The slowly coated samples with higher solids deposit were measured to be lighter and of higher chroma compared to samples coated at a higher speed. Generally, the color-changing effects were governed by the choice of RM and coating parameters in terms of variations of the amount of coating deposited onto the samples.

Retouching with Mica Pigments

Retouching with Mica Pigments

운모상에 인산아연이 도포된 방청안료의 제조 및 성능평가

인산아연이 도포된 운모 안료(ZP/mica)를 인산, 질산아연 그리고 운모를 출발물질로 하여 제조한 후, 방청안료로 사용하였다. 주사전자현미경 및 X-선 회절분석기 등을 이용하여 제조된 안료의 형상과 결정구조를 관찰하였다. 제조된 안료와 에폭시수지를 배합하여 도막을 형성시킨 다음 전기화학적 임피던스법을 이용하여 안료의 방청성을 평가하였다. <TEX>$70^{\circ}C$</TEX>에서 합성된 ZP/mica 안료의 방청성이 <TEX>$20^{\circ}C$</TEX>에서 제조된 안료보다는 우수하다는 것을 알 수 있었다. <TEX>$70^{\circ}C$</TEX>에서 합성된 ZP/mica 안료표면에는 <TEX>$Zn_3(PO_4)_2{\cdot}2H_2O$</TEX> 이외에도 ZnO가 동시에 생성되어 있음을 볼 수 있었다. 합성된 ZP/mica 안료의 우수한 방청성은 운모표면의 아연화합물에 의한 전기화학적 방청기구와 판상구조의 운모에 의한 장벽 방청기구의 상승작용에 기인한 것으로 생각된다. The zinc phosphate-coated mica (ZP/mica) pigments were prepared using phosphoric acid, zinc nitrate and mica as starting materials, and used as anticorrosive pigments. The scanning electron microscopy (SEM) and x-ray diffraction (XRD) techniques were used to observe the morphology and crystal structure of prepared pigments. The prepared pigments were incorporated into an epoxy binder to prepare coating and the corrosion inhibition performance of the pigments was evaluated using electrochemical impedance spectroscopy (EIS). It was found that the anticorrosive performance of the ZP/mica pigment prepared at <TEX>$70^{\circ}C$</TEX> was the better than that prepared at <TEX>$20^{\circ}C$</TEX>. The formation of ZnO, in addition to <TEX>$Zn_3(PO_4)_2{\cdot}2H_2O$</TEX>, was observed on ZP/mica pigment prepared at <TEX>$70^{\circ}C$</TEX>. The excellent anticorrosive performance of ZP/mica pigment could be ascribed to the synergistic effect with electrochemical anticorrosive mechanism from zinc compounds on mica and barrier anticorrosive mechanism from lamellar mica.

Properties of surface-treated mica in anticorrosive coatings

The paper deals with using lamellar mica pigments for anticorrosive barrier coatings. By depositing a ferric oxide layer on a muscovite particle a novel pigment is obtained. The use of these pigments in coatings improves the mechanical properties and the resistance to UV radiation. The pigment acts as an active barrier.

The preparation and characteristics of pigments based on mica coated with metal oxides

Intensively coloured mica pigments based on mica flakes covered with surface oxide–hydroxide layer of different metals, such as Ti, Cr, Fe, Al, Co, Ni, Zn and Cu were prepared by homogeneous precipitation of metal sulphates with urea in the presence of mica flakes. The final colour was obtained by thermal annealing of precipitates at temperature 150–800 °C.

Characterising special-effect colours

Special-effect colours, such as those produced by coatings containing metallic and mica pigments, have rapidly grown in popularity over the last 50 years. Originally used to give glamorous metallic effects on top-of-the-range cars, they are now widely used in products such as cosmetics, mobile phones and packaging materials.

Behaviour of surface-treated mica and other pigments with lamellar particles in anticorrosive coatings

The paper deals with using lamellar pigments for anticorrosive barrier coatings. By depositing a ferric oxide layer on a muscovite particle a pigment is obtained, which being applied to coatings improves the mechanical properties thereof, resistance to UV radiation and acts as an anticorrosion barrier. The optimum concentration of lamellar surface-treated muscovite in the coatings amounts to 20 vol. %.

The effect of zirconium oxide and quartz pigments on the heat and corrosion resistance properties of the silicone based coatings

Silicone resin based protective coatings are generally used for high temperature applications. In this work, anti‐corrosive and heat resistant properties of titanium dioxide, mica, zirconium oxide and quartz combination pigments with silicone resin as carrier vehicle in primer and top coat for mild steel surface have been evaluated. Promising results were obtained, showing that the ceramic pigments (zirconium oxide and quartz) impart heat‐resistance protection for steel substrate up to 370°. Electro‐chemical impedance spectroscopy, immersion studies and salt spray test results show good corrosion protection for the steel surface.

Monte Carlo simulation of light scattering on turbid layers with spherical pigment grains

Visible-light scattering on glass spheres in resin is considered as qualitatively representative of the actual situations of visible effects due to coatings or plastic sheets with non-absorbing pigments like mica pigments. Diffuse reflection and transmission are simulated by the Monte Carlo technique. The model consists of glass spheres in acrylic resin with section between 7.5 and 30 µm such that geometrical optics can be applied. Phenomena like shot and iridescent effects are described.

Mica pigments in solvent free coatings systems

Mica pigments are nowadays extensively used in different solvent containing paint systems, e.g. in automotive paints. Although water-borne coatings are gaining more and more importance, the need for even more environmentally safe to use coatings calls for coatings with less or even no solvents. To achieve this goal—no solvents—basically two technologies are used: one is powder coating, the other is radiation curing like UV- and electron beam-curable systems. Together with the need for more environmentally safe paint systems the consumer also requests highly esthetic coatings, especially concerning colour and effect. This paper describes how mica pigments, which are themselves environmentally safe and are used for high esthetic requirements, work in solvent free paint systems like powder coating and radiation-curable systems. Special attention is given to how mica pigments can be incorporated into powder coatings and what measures have to be taken to achieve an optimised effect. Concerning radiation, especially UV-curable systems, the advantages of mica pigments compared to other effect pigments are discussed.

Conservation of the Darnault Mirror: An Acrylic Emulsion Compensation System

AbstractA 1751 French boiserie mirror, which retained approximately 30% of its original gilding, was treated at the J. Paul Getty Museum. In the initial phase of the treatment, the mirror frame was thoroughly analyzed, its condition was documented, and testing of possible cleaning and compensation methods was begun. Ultimately, the conservators were not pleased with the results of that work, which was presented in a paper at the AIC Annual Meeting in 1994. Re-evaluation of the treatment led to the use of new materials for a barrier coat and for compensation of the losses in the gilding, including acrylic emulsion medium, mica pigments, and gold leaf. In creating the alternative system, the conservators and curators aimed to maintain the original goals of the project, including the proper interpretation and display of the mirror in the galleries as well as preservation of the physical integrity of the object. Methods for using nontraditional materials in a manner complementary to the original materials wer...