Composite Pigments Research Articles

Preparation and Infrared Reflection Performance of Al/Cr2O3 Composite Particles

The composite pigments were prepared by co-precipitation coated Cr2O3 on the surface of flake alumi- num powders. Phase structure, surface morphology and reflectance spectra of the composite pigment were charac- terized by XRD, FE-SEM, UV/VIS/NIR spectroscopy and Fourier transform infrared spectrometer. The result shows that the influence of cover treatment with Cr2O3 on the reflectance spectra at various radiation wavelengths is different. The shorter the wavelength is, the stronger the influence is. When the molar ratio of Cr 3+ to Al is 0.2:1.0, compared with the uncoated flake aluminum powders, its average reflectance of visible spectrum and brightness (L*) drop to 50% and 15, respectively. However, the infrared emissivity of 8-14 μm waveband increases less than 10%. It mainly ascribes to the difference of surface roughness and absorption coefficient for different radiation wave- lengths. Thus, the composite particles play a vital role in designing the low infrared emissivity coating.

The effect of polymer morphology on the performance of a corrosion inhibiting polypyrrole/aluminum flake composite pigment

Two different morphologies of polypyrrole (PPy) aluminum flake composites, namely spherical PPy/Al flake composites and wire PPy/Al flake composites, were synthesized by chemical oxidative polymerization. These composites were characterized by Fourier transform infrared spectroscopy (FT-IR), four point probe conductivity, conductive atomic force microscopy (C-AFM), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). These composites were incorporated into an epoxy primer and coatings were applied on an aluminum alloy (AA 2024-T3) substrate. The coatings were exposed to salt spray according to ASTM B117 and prohesion conditions according to ASTM G85-A5. The corrosion resistance properties were monitored via electrochemical impedance spectroscopy (EIS). The current produced by corrosion reactions on the surface of the substrate was mapped using the scanning vibrating electrode technique (SVET). Galvanic coupling experiments were performed for measurement of galvanic current and mixed potential in controlled environment. It was observed that the morphology of PPy on the surface of aluminum flake has an effect on the conductivity and anticorrosion performance of the pigment. The wire PPy/Al flake composite coatings exhibited better anticorrosion performance than the spherical PPy/Al flake composite coatings and as received aluminum flake coatings. The enhancement in anticorrosion performance was attributed to the unique morphology and electrochemical activity of the PPy on the surface of aluminum flakes. It was also revealed that the wire PPy/Al flake composite coating was sacrificially protecting the AA 2024-T3 substrate in larger defects.

Effects of composite ferrotitanium on epoxy coating

PurposeThe purpose of this paper is to evaluate effects of different contents of composite ferrotitanium pigment on corrosion protection performance of epoxy resin coatings.Design/methodology/approachDifferent contents of composite ferrotitanium pigment were added to the epoxy resin coatings and the corrosion performance of the coatings were investigated by electrochemical test (in 5 wt.% KCl solutions at 60°C), salt spray test and simulated test. The morphology of the coating before and after corrosion was characterised by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS).FindingsThe composite ferrotitanium improved anti‐corrosion properties of the coating due to complex reaction of ferrous ions and phosphates as well as introduction of nano powder to the composite ferrotitanium. The coating with 10 wt.% composite ferrotitanium pigment had better anti‐corrosion properties than that of 5 wt.%. Simulated experiment in an autoclave indicated that the composite ferrotitanium pigment had the best protective performance among the three green pigments such as zinc phosphate, aluminium tri‐phosphate, and composite ferrotitanium.Research limitations/implicationsThe pigments were added into the coating by high energy ball milling. Some of them dispersed in the coating heterogeneously and affected property of the coatings.Practical implicationsComposite ferrotitanium can be used to replace red lead and chromate pigments to meet environmental requirements.Originality/valueThe paper shows how the anti‐corrosion mechanism of the composite ferrotitanium pigment was investigated and several green pigments were selected to compare their protective performance in the autoclave.

Characterization and Electrochemical Investigations of Polypyrrole/Aluminum Flake Composite Pigments on AA 2024-T3 Substrate

Phosphate and nitrate doped Polypyrrole (PPy)/Aluminum (Al) flake pigments were synthesized by chemical oxidative polymerization method. Coatings were formulated from the phosphate doped PPy/Al flake pigment, nitrate doped PPy/Al flake, and as received Al flakes at 20% pigment volume concentration (PVC). The anticorrosion properties of coatings on aluminum alloy (AA 2024-T3) were monitored by exposure with accelerated salt spray (ASTM B117), electrochemical impedance spectroscopy (EIS), scanning vibrating electrode technique (SVET), and anodic polarization experiments. Phosphate and nitrate doped PPy/Al flake coatings showed enhanced anticorrosion ability in comparison with as received Al flake coating as observed in accelerated salt spray test. In the anodic polarization experiments, phosphate and nitrate doped PPy/Al flake coatings exhibited a positive shift in the potential suggesting the passivation of the substrate. Additionally, SVET experiments did not detect appreciable corrosion activity for the samples demonstrating better corrosion protection ability of phosphate and nitrate doped PPy/Al flake coatings.

Host-Mediated Synthesis of Cobalt Aluminate/γ-Alumina Nanoflakes: A Dispersible Composite Pigment with High Catalytic Activities

Cobalt aluminate/γ-alumina (CoAl(2)O(4)/γ-Al(2)O(3)) nanocomposite pigment with mesoporous structure has been synthesized. The method simply involves adsorption of Co(2+) ion on the surface of a commercially available boehmite (AlOOH) powder followed by the reaction of Co(2+) and AlOOH at relatively low temperature (500 °C) to obtain CoAl(2)O(4)/γ-Al(2)O(3) composite nanopowders. The formation of γ-Al(2)O(3) from boehmite induces the in situ generation of isostructural CoAl(2)O(4) (both crystallize as cubic spinel) at such a low temperature. The obtained intense blue powder of optimal composition (53.6 wt % CoAl(2)O(4) in γ-Al(2)O(3)) can be dispersed in glycerol and characterized by UV-visible, X-ray diffraction, Raman spectroscopy, TEM, and nitrogen sorption analyses. Raman studies confirm the formation of CoAl(2)O(4) phase in γ-Al(2)O(3). TEM studies reveal the formation of flake shaped (5-10 nm in width and 10-25 nm in length) nanopowders, and these flakes are assembled to form mesoporous structure. The specific surface area, total pore volume and average pore diameter of this powder are estimated to be ~118 m(2) g(-1), 0.1375 cm(3) g(-1), and 4.65 nm, respectively. This composite nanopowder has been used as an active catalyst for the decomposition of H(2)O(2) at room temperature and the decomposition follows the first order kinetics with rate constant value close to 2.3 × 10(-2) min(-1). This pigment nanopowder can be reused for several cycles without noticeable degradation of its original catalytic activity.

Preparation and characterization of inorganic colored coating layers on lamellar mica-titania substrate

The inorganic colored composite pigments, such as Fe2O3-, Bi4Ti3O12-, and CoAl2O4-coated mica-titania composites, were prepared by hydrolysis of FeCl3, Bi(NO3)3, and Co(NO3)2/Al(NO3)3 in the presence of mica-titania substrate and calcination at different temperatures. The inorganic coating layers on mica-titania substrate surfaces were explored by X-ray diffraction, scanning electron microscopy, Fourier transform infrared, and X-ray photoelectron spectroscopy. Dense and uniform Fe2O3 coating layers were formed on the surfaces of mica-titania substrates. At lower Bi2O3 loading, Bi4Ti3O12 nanoparticles were formed on the surfaces of mica-titania substrates. But at higher Bi2O3 loading, Bi4Ti3O12 nanosheets were formed and perpendicularly oriented to the substrate surfaces. CoAl2O4 nanosheets were formed on the mica-titania substrates and perpendicularly oriented to the substrate surfaces. The pigmentary performances of the inorganic composite pigments were analyzed by CIE, indicating that red, yellow, and blue colored pigments were achieved by coating Fe2O3, Bi4Ti3O12, and CoAl2O4 on mica-titania substrate surfaces, respectively. The pigmentary performances of the inorganic composite pigments were significantly affected by the morphology and loading of inorganic coating layers.

Deposition of colored inorganic coating layers on lamellar sericite surface and the pigmentary performances

The inorganic composite pigments, Fe 2O 3/sericite, Bi 2O 3/sericite, and CoAl 2O 4/sericite, were prepared by the homogeneous hydrolysis of metal salts, such as FeCl 3, Bi(NO 3) 3, and Co(NO 3) 2/Al(NO 3) 3. The deposition of the inorganic coating layers on sericite surfaces was explored by X-ray diffraction, scanning electron microscopy, Fourier transform infrared, and X-ray photoelectron spectroscopy. The inorganic coating layers were uniformly and tightly anchored at sericite surfaces via chemical bonding at the interface between the coating layer and the sericite substrate. The pigmentary performances of the inorganic composite pigments were analyzed by CIE, indicating that red, yellow, and blue colored pigments were achieved by coating Fe 2O 3, Bi 2O 3, and CoAl 2O 4 on sericite surfaces, respectively. The pigmentary performances of the inorganic composite pigments were significantly affected by the morphology and thickness of inorganic coating layers.

Coupling Interactions between Active Particulates and Aluminum Substrates

PPy/aluminum flake composite pigment was synthesized in an aqueous chemical deposition reaction with catechol, phloroglucide, pyrrole, and ammonium persulfate. The pigment was then incorporated into an epoxy binder and was sprayed applied to sand blasted and degreased aluminum 2024 T3 panels. The panels were then exposed to ASTM B117 salt spray to determine how the PPy/Al flake composite would perform as a corrosion inhibitor. The panels were monitored using linear polarization (LP), scanning vibrating electrode (SVET), and coupling current measurements. From the results, it is apparent that the aluminum flake synthesized without polypyrrole afforded some cathodic protection to aluminum 2024 T3; however, the polypyrrole further activates the aluminum flake surface.

Synthesis of ZnO/Zn 2SiO 4/SiO 2 composite pigments with enhanced reflectance and radiation-stability under low-energy proton irradiation

ZnO/Zn 2SiO 4/SiO 2 composite pigments with nano-sized α-Zn 2SiO 4 interface phase were synthesized by a simple solid-state reaction method. It was found that the composite pigments exhibit significant improvement on the spectral reflectance and the proton radiation-stability compared with the pure ZnO pigment. The investigations have demonstrated that the enhancements on the spectral reflectance and the radiation-stability are attributed to the introduction of willemite Zn 2SiO 4 interface phase on the surface of ZnO matrix particles. In addition, the enhancement mechanisms of radiation-stability for ZnO/Zn 2SiO 4/SiO 2 composite pigments were discussed.

Novel nano‐composite particles: titania‐coated silica cores

PurposeThe purpose of this paper is to develop methods to produce white composite pigments consisting of a silica core with a titania shell.Design/methodology/approachSilica cores were coated with titanium dioxide (TiO2) via forced hydrolysis of a solution prepared from titanium tetrachloride (TiCl4). The morphology, surface charge and particle size of obtained composite particles were studied.FindingsDispersions of well‐dispersed composite particles, having silica cores of uniform size in the range from 300 to 500 nm with a homogeneous titania coating are obtained. The coating thickness corresponded to 150‐400 per cent by weight of titania based on the core. Modification of the silica core by incorporation of 1.5 aluminosilicate sites per square nanometre of core surface proves to be favourable in achieving a homogeneous coating on the silica core. Deposition of such titania coating is also favoured by agitating the dispersion well, keeping electrolyte content low, maintaining pH at 2.0 and the temperature at 75°C during the coating process.Research limitations/implicationsOnly TiCl4 is used as titania source. In addition, only silica cores obtained by Stöber synthesis are used while commercially available silica solutions made from sodium silicate are not used.Practical implicationsThe process offers a method of producing a white composite pigment with a narrow particle size distribution in order to maximise light scattering as well as using a core with lower density than the shell. This kind of particle would be of interest for coating applications and white inorganic inks.Originality/valueThe developed method provides a straightforward process to produce well‐defined composite particles.

Wlasciwosci pigmentow kompozytowych SiO2/barwnik i ich zastosowanie w kauczuku silikonowym

The modification of silica performed by mechanical frictioning of dyes into its surface occurring during intensive mixing has led to stable composite pigments (Table 1). Azo dye, antraquinone, perylene and indigothiazyne derivatives were used as dyeing agents. ,,Surface crayoning of silica reduces its specific surface area, particle aggregation tendency, and the formation of structures. It also lowers the filling activity towards silicon rubber thereby altering the interphase interaction resulting in an uneven dispersion of the composite pigments in the elastomer (Table 2, 3, Fig. 2, 3). Vulcanizates filled with the modified silica exhibited an increased resistance to color changes caused by weathering, however, their mechanical resistance decreased in comparison with rubber filled with unmodified silica (Table 4, 5).

A New Pigment Type: Colored Diblock Copolymer−Mica Composites

New mica−polymer composite pigments have been prepared and characterized. The pigments are prepared from mica surfaces by block copolymerization of butyl acrylate (BA) and a mixture of styrene (S) and a modified alizarin (A; dye). This is performed after physical adsorption of a radical initiator with a cationic group. Some of the copolymer was desorbed from the surface and characterized by 1H NMR, size exclusion chromatography, and UV−visible spectroscopy. This desorbed copolymer fraction had a number-average molecular weight of 140 000 g·mol-1 with chemical compositions of 16% and 84% M, respectively, of poly(butyl acrylate) (PBA) and poly(styrene−alizarin) [P(S−A)]. In addition, it had a yellow coloration when in the bulk form. The remaining mica composites were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, and X-ray diffraction. It was found that 0.07 molecules of block copolymer per nm2 of mica remained adsorbed on the mica surface. This leads to a surprising p...

Stability against color fading of azo dyes encapsulated in Ca-aluminosilicate mesoporous substrates

Light-fastness properties of composites involving mesoporous calcium-modified aluminosilicate substrates (MCM-41 structure) and dye (Lithol Rubine B) were examined. High surface area Al-MCM-41 materials synthesized in the presence of Ca2+ ions proved efficient hosts for Lithol Rubine B, yielding mesophase–dye composites with the highest light-fastness qualities, when compared to Ca-exchanged Al-MCM-41 aluminosilicates, to non composite pigment or to smectite–dye composites. The marked resistance of the new composites to fading was attributed to an optimized Ca–dye interaction favored by a controlled heating the Ca(OH)2-loaded mesoporous precursors, yielding tiny CaO particles, highly dispersed and retained onto the large internal surface of the substrate.

Light Fastness Properties of Acid Dye and Mesoporous Ca-Aluminosilicate Composite

Abstract Light-fastness properties of composites involving mesoporous Ca aluminosilicate substrates (MCM-41 structure) and acid dye (Lithol Rubine B) were examined. High surface area Al-MCM-41 materials synthesized in the presence of Ca2+ ions yielded the dye composites with the highest light fastness qualities, when compared to Ca2+ ion-exchanged Al-MCM-41 aluminosilicates, to non composite pigment or to smectite - dye composites.

Effects of coupling agents on mechanical properties of metal oxide-polymethacrylate composites

The effects of several coupling agents on the mechanical properties of metal oxide-polymethacrylate composites reinforced with titanium dioxide (TO 2), aluminium oxide (A1203), silica (SiO 2) and zirconium dioxide (ZrO 2), as fillers for opaque resins were assessed. The prepared composites consist of 24.75 wt% triethyleneglycol dimethacrylate (TEGDMA), 24.75 wt% 1,6-bis(methacryloxy-2-ethoxycarbonylamino)-2,4,4trimethylhexane (UDMA), 0.5 wt% benzoyl peroxide (BPO) and 50 wt% metal oxide filler. Three methacrylate coupling agents—methoxydiethyleneglycol trimethacryloyl titanate, 3-trimethoxysilylpropyl methacrylate and 2,2-di(allyloxymethyl)butyl trimethacryloyl zirconate—were used for surface treatment of TiO 2, SiO 2 and ZrO 2, respectively, while A1203 was treated with 4-methacryloxyethyl trimellitate anhydride (4-META). 4META was also adopted as a coupler for TiO 2, SiO 2 and ZrO 2 powders. Compressive and transverse strength specimens were prepared with the use of coupled or untreated filler and heat cured at 110°C and 0.5 MPa for 30 min. All coupled metal oxide composites had significantly higher compressive and transverse strengths than did untreated composites after 1 month's immersion in 37°C water. Scanning electron microscopy (SEM) of fractured TiO 2 composite surfaces after storage in water for 1 month showed an interface failure between TiO 2 filler and matrix resin for untreated TiO 2 composite and cohesive failures within the resin for treated specimen. Similar results were observed with silanated SiO 2 composite. However, cohesive and interface failures were seen in zirconated ZrO 2- and 4-META-coupled A1203 composites. Thus, titanated TiO 2- polymethacrylate composite may be useful as a composite pigment for opaque resin materials.

接着強度の高い光重合型オペークレジンに関する研究

Light-cured adhesive opaque resins with high bond strength were prepared with the use of 4-methacryloxyethyl trimellitate anhydride (4-META), eleven methacrylate monomers and composite pigment. The purpose of this study was to investigate the relation between the monomer composition and the bond strength of the opaque resin. The shear bond strengths of ethyleneglycol dimethacrylate (1 G), diethyleneglycol dimethacrylate (2 G) and triethyleneglycol dimethacrylate (3 G)-based opaque resins were superior to those of other monomerbased opaque resins after thermocycles. A methyl methacrylate (MMA)-based opaque resin showed poor bond ability. 1, 6-bis (methacryloxy-2-ethoxycarbonylamino)-2, 4, 4-trimethylhexane (UDMA) effectively provided viscosity to the compositions. The prepared opaque resin, which consisted of 4-META/MMA-3 G primer, 3 G-UDMA base monomer and titanium dioxide-polymethacrylate composite pigment, bonded strongly to the alumina-blasted cobaltchomium alloy. This opaque resin may be useful to bond fixed prosthodontic composite and metal frameworks.

Production of composite pigments of iron oxide and carbon black : (Bayer Aktiengesellschaft) UK Pat 1 420 833 (14 Jan 1976)

Production of composite pigments of iron oxide and carbon black : (Bayer Aktiengesellschaft) UK Pat 1 420 833 (14 Jan 1976)

Characteristics of Pigments in Early Pencil Writing

PENCIL pigments may be classified in the following groups: (1) Metallic lead or alloys of lead; (2) graphite cut from the block; (3) early composite pigments containing graphite, sulphur, resins, etc., but no clay; (4) graphite powder compressed into blocks; and (5) composite pigments containing graphite with clay and other ingredients. These pigments usually show distinctive microscopic characteristics in the marks which they produce.