TiO2 Pigment Research Articles

The anticorrosion behavior and mechanism of Ti3C2 nanosheets for titania pigmented epoxy coatings

Utilization of Ti3C2 nanosheets for enhancing anticorrosion of epoxy resin coatings has been reported. But the epoxy coatings in real world are mainly pigmented coatings. Unfortunately, the anticorrosion behavior of Ti3C2 nanosheets for the pigmented epoxy coatings is rarely concerned. In this work, both 0.5 wt% unmodified Ti3C2 nanosheets (U-Ti3C2) or 0.5 wt% (3-glycidyloxypropyl)trimethoxysilane-modified Ti3C2 nanosheets (G-Ti3C2) were introduced into solvent-based titania pigmented epoxy coatings. Corrosion resistance of coatings was evaluated by electrochemical impedance spectroscopy and salt spray tests. A titania concentration effect was interestingly exhibited for the anticorrosion behavior Ti3C2-containing pigmented coatings. Enhanced anticorrosion was only demonstrated when TiO2 content was not above 10 wt% for U-Ti3C2 or 5 wt% for G-Ti3C2. Moreover, the pigmented coatings with U-Ti3C2 have better corrosion resistance than those with G-Ti3C2, being contrary to the phenomenon observed in pure epoxy resin coatings. The different anticorrosion behavior of Ti3C2 nanosheets for epoxy coatings with various TiO2 contents was mainly attributed to the different dispersion states of TiO2 pigments, that is, improved dispersion at low TiO2 content and deteriorated dispersion at high TiO2 content, after addition of Ti3C2 nanosheets.

Adaption of in vitro and in chemico phototoxicity tests for tattoo pigments and the effect of adsorption of the phototoxic contaminant benzo[a]pyrene to carbon black

Phototoxicity plays an important role in tattoo toxicology due to the skin's daily exposure to sunlight and the permanent deposition of pigments in skin. Here, we investigated in chemico reactive oxygen species generation using 2′,7′-dichlorodihydrofluorescein diacetate and in vitro phototoxicity towards skin fibroblasts based on the OECD Test Guideline 432.Proficiency substances, titanium dioxide (TiO2, anatase 30 nm, anatase 100 nm, rutile 30 nm), pigment red 22 (PR 22) with and without purification and carbon black (CB) were investigated. Phototoxic properties of benzo[a]pyrene (B[a]P) were investigated with and without adsorption to CB. Pigments were characterised by dynamic light scattering.All proficiency substances except for norfloxacin were predicted successfully and only TiO2 anatase exhibited phototoxicity in the cell-based approach. B[a]P showed the expected phototoxicity in contrast to B[a]P bound to carbon black. Upon UVA irradiation, only TiO2 pigment anatase and PR 22 generated ROS in the cell-free assay. DLS measurements showed a high degree of polydispersity/agglomeration.OECD Test Guideline 432 should be applied with an incubation time of 24 h when testing highly insoluble pigments. The in chemico ROS assay introduced below might serve as a quick screening test but may be further adapted to predict the in vitro outcome.

Composition control of additively manufactured color-graded temporary veneer

ObjectiveThe aim of this study was to design and assess composite resin composition for patient-specific esthetic color-graded temporary veneer. MethodsVarious compositions of composite structures (assorted by Ba2SiO4 filler, TiO2 pigment, and photoinitiator) were prepared via additive manufacturing with 3 s UV exposure (405 nm, 10 W/cm2) per 50 µm thick layer followed by 20 min post-curing treatment after fabrication. The effect of each component on the generated color shades was observed and compared to the commonly used VITA shade guide. The coloration was explored by staining aging treatment under dry, wet, artificial saliva environments, coffee, and cola. The mechanical properties were also evaluated. Color measurement and comparison were done using a colorimeter (lightness (L*), green-red color (a*), and blue-yellow color (b*)), and the changes were calculated by CIEDE2000 (ΔE00), translucency parameter (TP) and whiteness index (WID). The composition color analysis results were then applied to produce a color-graded temporary veneer for mimicking a natural look. ResultMechanically, all composition result in adequate bending strength with maximum achievable strength of 111.64 MPa. At the same time, the composite color was affected by each constituent differently. The L* value, which indicates the color lightness of the composite, was considerably tuned by the TiO2 pigment, whereas Ba2SiO4 filler only triggered minor changes. Photoinitiator concentration significantly affected the yellowness, indicated by the increased b* value. Similar tendency also observed toward the calculated TP and WID as well. Based on these evaluations, color-graded temporary veneer successfully generated, matching the VITA A3, A2, and B1 shades gradation. However, the stability of the composite color decreased at high amounts of Ba2SiO4 and photoinitiator. SignificanceThe study presents a composition guide for fabricating temporary patient-specific color-graded veneer. It provides insights on the effect of the constituent material on dental esthetics.

Study of the photo-stability of ceramic thermal control coating based on aluminium oxide

The study examined the photo-stability of the thermal control coating (TCC), a class of “Optical Solar Reflectors”, used in spacecrafts. This TCC is achieved by applying a layer of dielectric ceramic paste (DCP) onto the substrate using a printer (PCB printing). The DCP was prepared from filler (ground Al2O3 ceramic) and solvent with thickener (terpineol with ethylcellulose). The coating obtained by high-temperature firing (T = 850 оC, 2 h) has high reflectivity in the solar range of the spectrum (0.2–2.5 μm) with the solar absorptance (αs) of DCP equal to 0.143. It has high adhesion and photo-stability that exceeds photo-stability parameters of ZnO, TiO2, BaSO4, and CaSiO3 pigments. The developed coating can be recommended not only as a TCC for spacecrafts, but also as a protective or dielectric layer in manufacturing of printed circuit boards in various fields of technology, where increased resistance to solar radiation or its ultraviolet region is required.

Indoor paint life cycle particle release: Safer-by-design products and the importance of choosing the right formula

In 2020, the European Commission published a regulation that states all producers of white paints containing titanium dioxide (TiO2) must provide a warning label on their products. Exposure during the production and application of products containing TiO2 can be harmful, and therefore these products must be labeled as “may cause cancer.” The paint industry is a major user of TiO2 pigment. This study focuses on pigment release from three TiO2-based paints and discusses the effect of paint formulation, more precisely the Pigment Volume Concentration (PVC), to predict TiO2 pigment release from the paints during a simulated use phase and at the end of life (EoL). The use phase considered mild abrasion of painted panels that simulated cleaning or touching. The EoL phase was studied using leaching tests simulating landfill disposal. TiO2 release during both activities was evident with a high discrepancy between the three paints. While dry rubbing was similar for all paints, activities involving water present a high release link to paint matrix degradation. The paint pigment volume concentration and the paint permeability determines the TiO2 release during wet rubbing and leaching. This work represents an attempt to identify the paint permeability as a matrix-related parameter to predict TiO2 release and a way to use of this parameter to develop safer products.

Comparative electron microscopy particle sizing of TiO2 pigments: sample preparation and measurement.

Titanium dioxide (TiO2) pigment is a non-toxic, particulate material in widespread use and found in everyone's daily life. The particle size of the anatase or rutile crystals are optimised to produce a pigment that provides the best possible whiteness and opacity. The average particle size is intentionally much larger than the 100 nm boundary of the EU nanomaterial definition, but the TiO2 pigment manufacturing processes results in a finite nanoscale content fraction. This optically inefficient nanoscale fraction needs to be quantified in line with EU regulations. In this paper, we describe the measurement procedures used for product quality assurance by three TiO2 manufacturing companies and present number-based primary particle size distributions (PSDs) obtained in a round-robin study performed on five anatase pigments fabricated by means of sulfate processes in different plants and commonly used worldwide in food, feed, pharmaceutical and cosmetic applications. The PSDs measured by the three titanium dioxide manufacturers based on electron micrographs are in excellent agreement with one another but differ significantly from those published elsewhere. Importantly, in some cases, the PSDs result in a different regulatory classification for some of the samples tested. The electron microscopy results published here are supported by results from other complementary methods including surface area measurements. It is the intention of this publication to contribute to an ongoing discussion on size measurements of TiO2 pigments and other particulate materials and advance the development of widely acceptable, precise, and reproducible measurement protocols for measuring the number-based PSDs of particulate products in the size range of TiO2 pigments.

Investigation of TiO2 replacement alternatives for water-based paints using styrene butyl acrylate

Purpose Titanium dioxide (TiO2) has high opacity, high brightness and whiteness, owing to its high refractive index value. It is mainly used in the coating industry and continuous efforts have been made to replace some of the TiO2 in paint with new pigments. This study aims to replace part of TiO2 pigment with various percentages of BaSO4, CaCO3 and kaolin in styrene butyl acrylate-based paint formulations, without changing the properties of paints using only titanium dioxide. Design/methodology/approach To determine the optimum use rate of new pigment mixing, opacity, gloss, scrub resistance and weather resistance properties have been investigated in the water-based paint formulation. The morphological properties of these samples were examined by scanning electron microscopy analysis. Findings In the total color change (ΔE) measurements, it was observed that the sample coded 85Ti/15Ba produced extremely similar results to the situation when TiO2 was used alone. It was seen that the best results were obtained when 85Ti/15Ba was used instead of TiO2. Originality/value Comparison research on the impact of replacing TiO2 with BaSO4, CaCO3 and kaolin on the performance characteristics of water-based styrene butyl acrylate-based paint formulations has not been done in the literature, according to the literature search.

Influence of metal and nonmetal doping on wetting and dispersing characteristics of TiO2 pigment for coating applications

BackgroundDispersing of pigment particles in paint medium is the hardest stage in paint and coating production. Pigment agglomerates must be wetted, separated, and dispersed in paint matrix with a suitable distance from each other. MethodsIn the present work, we have studied the effect of doping of TiO2 pigment with metallic and nonmetallic elements on its wetting and dispersing properties. For this reason, TiO2 pigment was doped with Cu as a metallic and N as a nonmetallic element. Doped pigments were characterized by XRD, SEM, and FTIR and then wetting properties of the obtained pigments were tested by contact angle measurement with water. Also dispersing properties of pigments were studied by grinding time (dispersing time) in the ball mill apparatus. Significant findingsThe results showed that doping of TiO2 pigment with metallic element Cu reduced the contact angle whereas doping with non-metal element N caused to increase in the contact angle. Also, a complete test series of coatings prepared with these two doped pigments in comparison to unmodified pigments showed that the final properties of the paint film weren't affected by utilizing doped pigments.

Life cycle environmental impact assessment of titanium dioxide production in China

Titanium dioxide (TiO2), a widely used superior and versatile material, has imposed considerable energy and environmental impacts with its increasing demand and production. To guarantee the sustainable development of TiO2, this study assesses and forecasts the multiple environmental impacts of two mainstream TiO2 production technologies using the life cycle assessment (LCA) method. Results show that toxicity is the dominant environmental impact caused by TiO2 production. The chloride route has better environmental performance than the sulphate route except for global warming. Sulfuric acid, electricity, and steam are the key factors contributing to environmental burdens. Production of TiO2 pigment is the key stage to cause environmental impact for the sulphate route, whereas, the production of high‑titanium slag and TiO2 pigment are dominant stages for the chloride route. Nonrenewable-fossil is the largest source of cumulative energy demand (CED) consumption in both routes. Therefore, scenarios on renewable electricity transition under carbon neutral target and enhancing chloride route are simulated, revealing a 43% reduction of environmental impact mitigation potential. Finally, policy implications on the transition to renewable energy, chloride technology, and circular economy for TiO2 production are proposed.

Co-Removal of Fe/V Impurity in H2TiO3 Synthesized from Ti-Bearing Blast Furnace Slag.

Ti-bearing blast furnace slag (TBFS) can be converted to impurity bearing TiOSO4 solution for TiO2 pigment production. However, the H2TiO3 (MTA) hydrolyzed from the solution has too high Fe/V impurity to meet the standard for TiO2 pigment. In this study, we found that Fe3+ and V3+ were easily hydrolyzed and entered the MTA lattice, and hence could not be removed by washing. Furthermore, Fe/V was hard to co-remove by the traditional reduction method. Therefore, the Fe/V non-hydrolysis condition (Ti3+ = 0.01 M, F = 3.0, T = 130 °C; Ti3+ = 0.01 M, F = 3.5, T = 150 °C) was determined by thermodynamic calculations. However, at these conditions, the Ti hydrolysis ratio was low or the reaction time was long. Therefore, a new two-step hydrothermal hydrolysis process was proposed. Step 1 (130 °C, 2 h) ensured the non-hydrolysis of V3+, and Ti was partially hydrolyzed to increase the H2SO4 concentration. Step 2 (150 °C, 2 h) ensured a high Ti hydrolysis ratio (>0.95) and short total reaction time (4-6 h). Finally, a high-purity MTA was obtained (Fe = 21 ppm, V = 145 ppm). These results provide new insights into the control of the hydrolysis of impurity ions in solutions and help to optimize the process of TiO2 pigment preparation from TBFS.

Preparation and dispersion properties of polyacrylate copolymer dispersant

Purpose The purpose of this paper is to synthesize a polyacrylate-based dispersant with a determined target molecular weight for oily systems and to determine the optimal dispersant level and monomer ratio of the dispersant. Design/methodology/approach The dispersant was synthesized by conventional radical polymerization using methacrylic acid, butyl acrylate and dimethylamino ethyl methacrylate as the monomer. It was characterized by Fourier transform infrared spectroscopy, nuclear magnetic hydrogen spectroscopy, gel permeation chromatography and thermogravimetric analysis. The dispersant was used to disperse TiO2, and the performance of the dispersant was evaluated by measuring the viscosity, particle size and dispersive force of the slurry. Findings The dispersant exhibited high thermal stability and was successfully anchored to the surface of the TiO2 pigment. When used to disperse a TiO2 slurry, it effectively made the TiO2 slurry more fluid, indicating its strong viscosity-reducing properties. The viscosity, particle sizes and dispersion capabilities of the TiO2 slurry were found to vary depending on the contents and monomer ratios of the dispersant. Research limitations/implications P(MAA-BA-DM) dispersant increases the wettability of TiO2 only in oily solvents but not in aqueous solvents. Practical implications P(MAA-BA-DM) dispersant makes it easier to disperse TiO2 pigments in oily solvents, increasing the amount of pigment in the solvent and making the preparation of highly pigmented pastes easier. Originality/value A dispersant containing suitable carboxyl and tertiary amine groups was initially synthesized to disperse TiO2 in an oily system. The findings are anticipated to be used in the formulation of pigment concentrates, industrial coatings and other solvent-based coatings.

Defect-induced regulation of crystal growth and phase transition of TiO2 synthesized from Ti-bearing blast furnace slag

Ti-bearing blast furnace slag (TBFS) is an essential secondary Ti resource for TiO2 production. However, the TiO2 is sintered and does not meet the pigment requirements. This study investigated the effect of surface/bulk distribution of defect structures on the crystal growth and phase transition of TiO2 based on the Rietveld method. For the defects of Xn+ (Al3+/Mg2+/Zn2+), the interstitial Xn+ (Xint) is mainly located on the surface of TiO2 particles and inhibits the crystal growth. The substituted Xn+ (Xsub) is primarily located in the bulk and promotes the phase transition. The radius of Xn+ affects the stability of Xint and determines the distribution of Xint/Xsub. Thus, the major defect structures of Al3+, Mg2+, and Zn2+ (increasing radius) are Alint, Mgint/Mgsub, and Znsub, respectively. Based on this, a new co-doping method was proposed. Co-doping modifies the distribution of Xint/Xsub to regulating the crystal growth and phase transition. Finally, TiO2 for pigment with a small particle size (220 ± 60 nm) and high rutile conversion (98.1%) was synthesized from TBFS. The results will help to optimize the process for producing TiO2 pigment from TBFS and provide new insights into the structure regulation of TiO2 materials.

Experimental Investigation of TiO2 Pigment Production by Electrodialysis Process from Ilmenite Concentrate

Experimental Investigation of TiO2 Pigment Production by Electrodialysis Process from Ilmenite Concentrate

Photocatalytic coloured rendering mortars: effect of TiO2 and iron oxide pigments on the physical, mechanical, hygric, and photoactive behaviour

Photocatalytic coloured rendering mortars: effect of TiO2 and iron oxide pigments on the physical, mechanical, hygric, and photoactive behaviour

Preparation of TiO2 pigment from ilmenite ore concentrate by molten alkaline process

TiO2 pigment production from an ilmenite concentrate via a molten alkaline process was investigated. The ilmenite concentrate (54.19% TiO2) was first roasted in the molten NaOH system at various temperatures ranging from 600 to 800°C while the mass ratio of NaOH/ilmenite was varied within the range of 0.8-1.2 for 1 hour. The achieved roasted efficiency was up to 93.93% at a temperature of 700°C and NaOH/ilmenite ratio of 1:1. The roasted product was first leached in water and then in a solution of HCl 20% at 50ºC for 2 hours. The TiOCl2 solution was hydrolysed at 95oC for 2 hours. Precipitation of the hydrolysis process was then calcinated at 800oC. The final obtained product contained up to 96.37% of TiO2. Ilmenite can be used as a raw material in a molten alkaline process. It is obvious that not only high purities of TiO2 could be achieved, but also the reduction of waste materials, raw materials, energy, and time.

Study of Titanium Dioxide (TiO2) Extraction Process from Ilmenite Banten

Ilmenite is found in the form of iron sand with reserves of 927,315,827 tons spread across several regions in Indonesia, including Banten which has seven million tons of iron sand. This mineral can be used as a raw material for making TiO2 pigments. The problem faced in the use of Ilmenite is its complex mineral structure which causes difficulties at the processing stage. The synthesis of TiO2 from ilmenite ore commonly used the sulfate process and the chloride process. The sulfate process is less environmentally friendly, has excessive costs, and produces a lot of liquid waste. While the chloride process requires high-grade raw materials and requires chlorine gas. Therefore, in this study, the synthesis of TiO2 from ilmenite Banten using caustic fusion, acid leaching using hydrochloric acid, and the use of citric acid were conducted. Caustic fusion is conducted with ratio between ilmenite and NaOH is 1:2, with a fusion temperature of 850 °C and a fusion time of 60 minutes. Then next process is water leaching and acid leaching. The result of this study is that the TiO2 obtained from each acid leaching is hydrochloric acid leaching producing powder pigment with 94.189% TiO2, acetic acid leaching producing 37.099% TiO2, citric acid leaching producing 41.480% and hydrochloric acid leaching without fusion process producing 43.991% TiO2.

Effects of Mg2+ doped TiO2 defect structures on TiO2 anatase-to-rutile phase transition

Rutile TiO2 is a competitive white pigment due to its high refractive index and inertness. Uncolored Mg2+ is a promising dopant for the production of TiO2 pigment because it promotes the anatase-to-rutile phase transition of TiO2 at lower temperatures (vs. Al3+). However, research on the impact of Mg2+ concentration on TiO2 phase transition is scarce, and the defect structures are still unknown. In this study, the effect of Mg2+ doping concentration on TiO2 phase transition was investigated, and the defect structures of Mg2+ doped TiO2 were proposed. Over 96% conversion of anatase to rutile was achieved with 1.48% Mg doping at 875 °C (vs. Al3+, 1050 °C) for 1 h. By using the Rietveld method, two defect structures—interstitial Mg2+ (Mgint) and substitute Mg2+ (Mgsub)—were quantified. A correlation between the defect structures and the effect on phase transition was established. At low Mg doping level (<1%), the Mgint dominates and weakly promotes the phase transition; At high Mg doping level (>1%), the Mgsub dominates and strongly promotes the phase transition. Additionally, a possible mechanism for the formation of defect structures and how that affects phase transition was proposed. The present results may provide insights into TiO2 pigment production and modulation of TiO2 defects for phase transition control and other applications.

Chinese TiO2 pigment prices increased for the third time so far this year

Chinese TiO2 pigment prices increased for the third time so far this year

Analysis of Adsorbed Polyphosphate Changes on Milled Titanium Dioxide, Using Low-Field Relaxation NMR and Photoelectron Spectroscopy.

In this study, changes in the adsorbed amount and surface structure of sodium hexametaphosphate (SHMP) were investigated for aluminum-doped TiO2 pigment undergoing milling. Relaxation NMR was utilized as a potential at-line technique to monitor the effect of milling on surface area and surface chemistry, while XPS was used primarily to consider the dispersant structure. Results showed that considerable amounts of weakly adsorbed SHMP could be removed with washing, and the level of dispersant removal increased with time, highlighting destructive effects of sustained high-energy milling. Nonetheless, there were no significant chemical changes to the dispersant, although increases to the bridging oxygen (BO) peak full width at half-maximum (FWHM) suggested some chemical degradation was occurring with excess milling. Relaxation NMR revealed a number of important features. Results with unmilled material indicated that dispersant adsorption could be tracked with pseudo-isotherms using the relative enhancement rate (Rsp), where the Rsp decreased with dispersant coverage, owing to partial blocking of the quadrupolar surface aluminum. Milled samples were also tracked, with very accurate calibrations of surface area possible from either T1 or T2 relaxation data for systems without dispersant. Behavior was considerably more complicated with SHMP, as there appeared to be an interplay between the dispersant surface coverage and relaxation enhancement from the surface aluminum. Nevertheless, findings highlight that relaxation NMR could be used as a real-time technique to monitor the extent of milling processes, so long as appropriate industrial calibrations can be achieved.

Porous polymeric microparticles foamed with supercritical CO2 as scattering white pigments

Nowadays, titanium dioxide (TiO2) is the most commercially relevant white pigment. Nonetheless, it is widely criticized due to its energy-intensive extraction and costly disposal of harmful by-products. Furthermore, recent studies discuss its potential harm for the environment and the human health. Environment-friendly strategies for the replacement of TiO2 as a white pigment can be inspired from nature. Here whiteness often originates from broadband light scattering air cavities embedded in materials with refractive indices much lower than that of TiO2. Such natural prototypes can be mimicked by introducing air-filled nano-scale cavities into commonly used polymers. Here, we demonstrate the foaming of initially transparent poly(methyl methacrylate) (PMMA) microspheres with non-toxic, inert, supercritical CO2. The properties of the foamed, white polymeric pigments with light scattering nano-pores are evaluated as possible replacement for TiO2 pigments. For that, the inner foam structure of the particles was imaged by phase-contrast x-ray nano-computed tomography (nano-CT), the optical properties were evaluated via spectroscopic measurements, and the mechanical stability was examined by micro compression experiments. Adding a diffusion barrier surrounding the PMMA particles during foaming allows to extend the foaming process towards smaller particles. Finally, we present a basic white paint prototype as exemplary application.