Search results

The function of metallic pigments may be protective or decorative, sometimes both at the same time. The ultimate use of the pigments will determine the most suitable particle structure, whether the product is a paint or a plastic or an elastic composition. Protection may be provided against atmospheric or marine corrosion on the one hand, or against radiation — light or heat — on the other. In the former, metallic pigments of various particle structures are suitable, while in the latter the optical effect desired can only be obtained, as a rule, through the use of flaky or lamellar pigments. This is also the case when the metallic pigment is intended for decorative uses.

This study aims to encapsulate the crude carotene pigment isolated from waste portion of Cucurbita maxima with the help of different encapsulating agents through lyophilization to transform crude pigment into stable form for further utilization.

This paper opted for encapsulation of extracted carotene pigment by lyophilization using various carrier materials such as maltodextrin 20 dextrose equivalent (DE), maltodextrin 10 DE and tapioca starch along with emulsifier polysorbate-80. After encapsulation of crude carotene pigment, prepared encapsulated powder was subjected to chemical analysis. The data was analysed statistically by a complete randomized design.

Maximum encapsulation efficiency, carotene content, antioxidant activity and water solubility index were achieved when 0.06% of crude carotene pigment was emulsified with same quantity of polysorbate-80, followed by encapsulation with 20% of maltodextrin 20 DE during lyophilization.

Even though few researchers have worked on the encapsulation of colour pigments, no researcher has reported encapsulation of carotene pigment extracted from waste of C. maxima.

As there is a strong inducement to develop new colored inorganic materials to substitute the current industrial pigments that are based on toxic metals hazardous to health and the environment, the purpose of this paper is to invent environmentally benign rare earth-based colorants as viable alternatives to the traditional toxic pigment formulations. Herein, the authors developed a series of rare earth pigments having the general formula Ca0.1 Ln0.9 PO4 ( Ln = Y , Pr , mixed rare earth oxides, RE and Di). After studying all the optical properties, the authors have gone for some coloring application in plastic like PMMA.

The designed pigments were synthesized by traditional solid-state method. Stoichiometric amounts of each reagent were mixed in an agate mortar and the mixtures were calcined at optimized temperature 1000 °C for 4 h in electric furnace followed by auto–cooling. The samples were characterized by X-ray diffraction diffraction, UV–vis spectroscopy, scanning electron microscope (SEM), particle size distribution, color coordinates determination, acid/alkali test, thermo gravimetric (TG) analysis and CIE–1976 L*a*b* color scales. Among the various lanthanide ions and calcium ion as dopant, the pigment composition shows various hues ranges from green to yellow. The designed pigments consist of non–toxic elements and were further found to possess high thermal and chemical stability. The pigments were also found to be appropriate candidates for the coloration of polymer substrates like PMMA.

The present investigations establish that various color hues can be achieved by the incorporation of suitable chromophore metal ions like calcium in various rare earth host lattice by tuning of the band gaps. The coloring mechanism is based on the strong absorption of the pigments in the blue and red regions due to electronic transitions of the micro states of rare earth ion. The pigment composition shows various hues ranges from green to yellow. The coloring mechanism is based on the tuning of band gap by the dopant like calcium in various rare earth host lattice. In addition, this pigment was chemically and thermally stable. Finally, it has applied in plastics like PMMA.

Mechanism of the color appearance using band calculations and on possible applications of rare earth phosphate powders as pigments in plastics and paints have not been explored much. However, the properties of the Ca-doped rare earth phosphate implies that this material has a potential to be applied as a satisfactory pigment for coating or coloring except for glaze, which may cause a side reaction at high temperatures, especially taking into consideration the economics and ecologies. The possibility of Ca2+ incorporation in CePO4 with monazite structure-type has been established.

The designed pigments consist of non-toxic elements and were further found to possess high thermal and chemical stability. The pigments were also found to be appropriate candidates for the coloration of polymer substrates. Thus, the present environmental friendly pigment powders may find potential alternative to the classical toxic inorganic pigments for various applications.

There is a strong incentive to design new colorants based on inorganic materials to substitute for industrial pigments that are based on heavy elements hazardous to health and the environment. However, several industrial yellow pigments such as cadmium yellow (CdS), chrome yellow (PbCrO4) and nickel titanium yellow (TiO2-NiO-Sb2O3) contain the harmful elements (e.g. Cd, Pb, Cr and Sb) for the human body as well as the environment. The designed pigments consist of non-toxic elements and were further found to possess high thermal and chemical stability. The pigments were also found to be appropriate candidates for the coloration of polymer substrates. Thus, the present environmental friendly pigment powders may find potential alternative to the classical toxic inorganic pigments for various applications.

There is a strong incentive to design new colorants based on inorganic materials to substitute for industrial pigments that are based on heavy elements hazardous to health and the environment. However, several industrial yellow pigments such as cadmium yellow (CdS), chrome yellow (PbCrO4) and nickel titanium yellow (TiO2-NiO-Sb2O3) contain the harmful elements (e.g. Cd, Pb, Cr and Sb) for the human body as well as the environment. So, the authors have developed new class of inorganic pigments that are both non-toxic and environmentally unimpeachable, while preserving or even exceeding the optical, thermal and chemical characteristics of the existing commercial pigments. The developed colorants find practical applications in polymer matrix like PMMA.

During the dispersion of a pigment in a given application medium, two main processes are taking place side by side. These are the wetting of the pigment surface by the binder components, and the actual dispersion process, i.e. the separation of agglomerates into primary particles or at least into smaller agglomerates by the application of mechanical energy.

One of the most fascinating aspects of the organic pigment scene today is its increasingly high degree of specialisation. Pigment manufacturers, in response to the ever changing requirements of the colour using industries have upgraded the quality of pigment powders, particularly with regard to colour strength, gloss transparency and rheology. Colour users, at the same time, have become considerably more knowledgeable about the optimum conditions required for producing a good, stable dispersion and using modern equipment, have been able to develop sophisticated dispersion techniques which enable them to ‘squeeze’ a lot more out of pigments than they did only a few years ago.

There is a strong inducement to develop new inorganic materials to substitute the current industrial pigments, which are known for their poor ultraviolet absorbent and low photoluminescence (PL) properties. The purpose of this paper is to invent a better rare-earth-based pigment material as a spectral modifier with good luminescence properties to enhance the spectral response for photovoltaic panel application.

Different phosphor samples made of nano-calcium carbonate (CaCO₃) with varied wt.% of the dopant Dysprosium doped calcium borophosphate (CBP/Dy) as (W0 – 0%, W1 – 3,85%, W2 – 7.41%, W3 –10.71% and W4 –13.79%) were prepared via the solid-state diffusion method at 600 °C for 6 h using a muffle furnace. The structural, morphological and luminescence properties of the CaCO₃:CBP/Dy powder samples were examined using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and PL test.

The XRD, SEM and FTIR results verified the crystalline formation, morphological behaviour and vibration bonds of synthesized CBP/Dy-doped CaCO₃ powder samples. XRD pattern revealed that the synthesized powder samples exhibit crystalline structured materials, and SEM results showed irregular shape and porous-like structured morphologies. FTIR spectrum shows prominent bands at 712, 874 and 1,404 cm⁻¹, corresponding to asymmetric stretching vibrations of CO3²⁻ groups and out-of-plane bending. PL characterization of CBP/Dy-doped CaCO₃ (sample W) shows emission at 427 nm (λmax) under the excitation of 358 nm. The intensity of PL emission spectra drops due to the concentration quenching effect, while the maximum PL intensity is observed in the W3 phosphor powder system.

This phosphor powder is expected to find out the potential application such as a spectral modifier which is applied to match the energy of photons with solar cell bandgap to improve spectral absorption and lead to better efficiency.

The introduction of a nano-CaCO₃:CBP/Dy hybrid powder system with good luminescence properties to be used as spectral modifiers for solar cell application has been synthesized in the lab, which is a novel attempt.

The purpose of this paper is to synthesize anticorrosion pigments of the perovskite type, YXO₃, where X = Ti, Zr, Mn or Al and Y = Ca, Sr, La or Fe, for coating materials intended for corrosion protection of metals. Also, to synthesize pigments containing hexavalent Mo and W (double perovskites).

The anticorrosion pigments were synthesized from oxides or carbonates by a high-temperature process. The following pigments were synthesized: CaTiO₃, SrTiO₃, CaZrO₃, SrZrO₃, LaTiO₃, LaMnO₃, CaMnO₃, SrMnO₃, LaFe₂O₃, SrFe₂O₃, LaAlO₃, Ca₂ZnWO₆ and Ca₂ZnMoO₆. The pigments were characterized by the physico-chemical properties of the powders, by X-ray diffraction analysis and by scanning electron microscopy. Epoxy-ester coating materials containing the pigments at a volume concentration PVC = 10 per cent were prepared and subjected to tests examining their physico-mechanical properties and tests in simulated corrosion atmospheres.

The perovskite structure was identified in the majority of the pigments. The pigments were found to impart good corrosion inhibiting properties to coating materials. The highest calculated anticorrosion efficiency was found for paints containing CaMnO₃ or SrMnO₃ as the pigments.

The pigments synthesized can be used with advantage in paints intended for corrosion protection of the substrate metals.

The use of the above pigments in anticorrosion coating materials to protect metals is new. Especially beneficial are the uses and procedures for the synthesis of anticorrosion pigments which do not contain heavy metals and are acceptable from the environmental protection aspect.

The purpose of this paper is to introduce an effective method to discriminate seal inks with Raman microscopy.

Raman spectra could effectively avoid interference from the paper and give extra peak information in the inks discrimination and identification. Thus, a Renishaw invia confocal Raman microscope system was employed for ink analysis in this study. A total of 12 representative seal ink samples, widely used in seven Chinese provinces, were investigated using the latest model of Renishaw Raman microscope.

Four types of inks were identified and discriminated successfully. Popular pigments such as Pigment Scarlet Powder, Pigment Yellow 55, phthalocyanine blue, Bronze red C and PbCrO3 were all identified in these seal ink samples. The indicative peaks to identify and discriminate the inks were also summarised and tentatively interpreted.

More ink samples were needed to establish a useful library. Many other pigments used in inks were still unknown.

This method was proved to be fast, accurate and non-destructive, and it could be more easily applied in real cases than Fourier transform infrared spectroscopy.

This method can help scientists discriminate some inks, which can hardly be discriminated by other techniques. The results are useful for the ink analysis and discrimination in forensic (document examination and file source identification), polymer and pigment fields.

This study aims to the effect of NaF, Li₂CO₃ and H₃BO₃ minerals was investigated, and the best mineralizer was found to be H₃BO₃. Furthermore, the effect of temperature was investigated, and the synthesized samples were calcined at temperatures of 1100, 1200 and 1300 °C to select the optimum calcination temperature.

This study was aimed at thoroughly investigating the effects of mineralizer addition and temperature on the synthesis of malayaite pink pigment based on raw materials of SnCl₂-SiO₂-Ca(OH)₂-K₂Cr₂O₇. To this end, the optimization of the synthesis parameters such as mineralizer addition and temperature was completely perused.

The optimum temperature was 1300 °C, and the color efficiency of pigments was evaluated by colorimetric (CIE L*a*b* system) analysis, and these parameters were close to those of industrial pigments.

To the best of the authors’ knowledge, for the first time, the effect of mineralizer addition and temperature on the synthesis of malayaite pink pigment was investigated through the sol-gel method. Herein, different parameters were optimized to propose a novel pigment with a much better performance.

The growth in the usage throughout industry of organic pigments has inevitably resulted in the availability of these raw materials in a variety of forms, designed to facilitate their incorporation into the specific media involved, and to minimise the problems associated with handling and processing.