Titanium Dioxide For

Product Overview




II. OPTICAL THEORY...... 4 Reflection...... 4 Refraction...... 4 Diffraction...... 5

Why TiO2?...... 6

TiO2 Particle Size...... 7 Scattering Power...... 7 Undertone...... 8 Volume Concentration (PVC)...... 8 Dry Flat Hiding...... 9 Scattering Efficiency and Opacity...... 9

TiO2 Surface Treatment...... 10 Color, Particle Size, and PVC...... 10 Extenders...... 11

III. OPTICAL PROPERTIES...... 11 Hiding Power and Tinting Strength...... 11 Color...... 12 ...... 13 Flocculation...... 14 Weatherability...... 14 Resistance and Gloss Retention...... 15 Standard Classifications...... 17

IV. END USES — TIO2 GRADE RECOMMENDATIONS...... 18 Interior Architectural ...... 18 Gloss and Semigloss Paints...... 18 Flat Paints...... 18 Exterior Architectural Paints...... 19 Industrial Finishes...... 19 Automotive OEM and Refinish Coatings...... 19 Powder Coatings...... 20 Other Industrials...... 21 Product Manufacture...... 22

V. THE TI-PURE™ OFFERING...... 24 Quality Assurance in Product Design...... 24 Quality Assurance in Product Manufacture...... 26 Product Packaging and Delivery...... 27 Technical Service...... 27 Samples/Order Placement...... 27


Titanium Dioxide for Coatings

™ This booklet is your guide to the use of Ti-Pure titanium dioxide (TiO2) in

coatings. It describes the properties and functions of TiO2 pigments in a manner useful as an introductory guide for those new to the industry, and useful as a reference guide to those with experience.

The first three sections describe titanium dioxide No booklet can replace direct, personal contact with pigments, their function as pigments in coatings Ti-Pure™ sales representatives and technical service

systems and properties of TiO2 pigments which affect personnel. For more information, please contact your

finished product performance. The fourth section regional Chemours TiO2 office. Telephone numbers and serves as your guide to selecting the right Ti-Pure™ web address are listed on the back cover. titanium dioxide grade for your specific application, Chemours ranks first among titanium dioxide and the last section describes the titanium dioxide manufacturers in production capacity, product quality, manufacturing process, quality assurance, and and customer service. As a worldwide supplier of Ti-Pure™ customer service. titanium dioxide pigments, Chemours is committed to maintaining a leadership position in these areas.

Ti-Pure™ titanium dioxide is made only by Chemours. The information set forth herein is furnished free of charge and based on technical data that Chemours believes to be reliable. It is intended for use by persons having technical skill, at their own risk. Because conditions of use are outside our control, we make no warranties, express or implied, and assume no liability in connection with any use of this information. Nothing herein is to be taken as license to operate under or a recommendation to infringe any patents.

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Titanium dioxide (TiO2) is the most photochemical, and physical power efficiency, chalk resistance, important white pigment used in the characteristics, are determined and resistance to discoloration by coatings industry. It is widely used principally by the particle size of the heat and/or photoreduction. Organic because it efficiently scatters visible pigment and the chemical composition surface treatments can enhance the light, thereby imparting whiteness, of its surface. Most commercial dispersibility of the pigment in selected brightness and opacity when grades of titanium dioxide have coatings systems. Numerous grades are incorporated into a coating. Titanium inorganic and in some cases organic produced with varying combinations of dioxide is commercially available in two surface treatments. Inorganic surface surface treatment to maximize value-in- structures— and . modifiers most often are precipitated use in a variety of coatings formulations. Rutile TiO pigments are preferred coatings of alumina and silica, which 2 It is inappropriate to equate superior because they scatter light more are meticulously controlled for type, performance of TiO pigment in efficiently, are more stable and are more amount, and method of deposition. 2 with high TiO analysis. For example, durable than anatase pigments. 2 These inorganic surface treatments Ti-Pure™ titanium dioxide grades

Titanium dioxide pigments are provide improvements in one or more specified at 80–88% minimum TiO2 insoluble in coating vehicles in which important performance properties content are markedly superior to higher- they are dispersed; accordingly, such as dispersibility in and content TiO2 grades in hiding power performance properties, e.g., chemical, in a range of organic liquids, hiding efficiency in some highly pigmented flat paints.

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Figure 1 reflected at the air-glass interface of from its original path. When the light Reflective Scattering each plate. If the stack were immersed enters a medium of higher refractive in oil until all air was displaced, or index, it is bent toward a line drawn compressed sufficiently that all air were perpendicular to the surface at the removed, the stack would become as entrance point. When the light emerges, transparent as the glass bar. A change it is bent away from this perpendicular. of promotes reflection. The greater the difference in refractive In this illustration, it is the difference in index between the particle and the refractive index of the glass (1.5) and medium, the more the light is bent. the air (1.0) that produces scattered In Figure 2, the sphere on the left has a reflections from successive surfaces higher refractive index than the sphere of the thin plates. In a like manner, on the right, thus bending the light more reflection of light will occur from sharply; the left sphere scatters more the surface of TiO pigments with 2 light than the right. high refractive index (2.7) in contact with various coatings vehicles at low Cross sections of two white paint refractive index (1.5). films are shown in Figure 3. In the Titanium dioxide (TiO ) and other 2 top illustration (high refractive index white pigments opacify paint films Refraction pigment), light entering the film travels primarily by diffusely reflecting light. a shorter path length than in the bottom This reflection occurs because the When light strikes a single high (in (low refractive index pigment). Both white pigment scatters or bends relation to the surrounding vehicle) films appear opaque and white, since light strongly. If there is enough white refractive index transparent particle, practically all incident light is returned pigment in a paint film, almost all visible the portion that is not reflected enters to the surface. If the films were reduced light striking it (except for a very small the particle and undergoes a deviation amount absorbed by vehicle or pigment) will be reflected, and the film will appear opaque, white, and bright. Figure 2 The primary control of opacity and Refraction of Light by Particles brightness in white paint films depends on scattering of light. Scattering of light means bending of light, and in coatings, light can be bent by surface reflection, by refraction and by diffraction.

Reflection Figure 1 shows light scattering by reflection. For the single glass bar over the black line on the right, the line shows clearly because light has been reflected only twice (front and back of the bar) and only a small amount (~4%) is reflected at each surface. At the left, a stack of thin glass plates at equal thickness to the bar is placed over the same black line. The Higher Refractive Index Lower Refractive Index line is invisible because light has been

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Figure 3 in thickness to “X” and placed over a Path of Light in White Paint Films black background, the top illustration would remain opaque and white, while the bottom containing the lower index pigment would allow some light to pass into the black background and be absorbed. This film would appear gray in comparison.

X X Diffraction The phenomenon of diffraction can be approached by consideration of one characteristic of wave motion. When a Higher Refractive Index Pigment wave passes an obstruction, it tends to bend from its original path. As an example, waves of water passing a vertical piling will bend in behind the piling. The same is true of light waves as they pass near an object, they tend to bend behind the object. With large objects the amount of bending is X X generally insignificant to the eye, but when the object’s dimensions approach the wavelength of incident light, bending (diffraction) becomes appreciable. Lower Refractive Index Pigment

When the size of the TiO2 particles approaches half the wavelength of Figure 4 incident light, the particles can bend Diffraction Around Particles four to five times as much light as actually falls on the particle because a large amount of the light is diffracted when it passes close to the particles. In other words, the scattering cross section can be four to five times the geometric cross section of the particles.

Figure 4 is a qualitative consideration of the difference between diffraction efficiency and particle size. The increase in diffraction at very small particle size (ideally one-half the wavelength of light desired to be scattered) is due to electromagnetic resonance between the particle and light. In other words, the particle tunes in to the light wave in the same way a radio antenna responds to radio waves.

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The ability of well-spaced particles of Table 1 well-controlled size to diffract light is a Refractive Indices (R.I.) for Pigments and Vehicles Used in the Manufacture of Paint major consideration in the design of fully functional coatings systems. White Pigments R.I. Vehicles or Media R.I.

Why TiO2? Diatomaceous 1.45 Vacuum 1.0000 TiO2 is unique in that it combines high refractive index with a high degree of Silica 1.45–1.49 Air 1.0003 transparency in the visible region of the spectrum (Figure 5). This combination 1.63 Water 1.3330 affords the coatings formulator a route to highly opaque and bright or 1.64 Polyvinyl acetate resin 1.47 tints at minimum film thicknesses. Clay 1.65 Soybean oil 1.48

To understand why TiO2 and especially silicate 1.65 Refined linseed oil 1.48 rutile TiO2 offer such great advantages in hiding, it is only necessary to 1.84 Vinyl resin 1.48 compare the refractive indices of rutile and anatase with those of other 2.02 Acrylic resin 1.49 commercial white pigments and paint vehicles (Table 1). The larger the oxide 2.09–2.29 Tung oil 1.52 difference between the refractive index of the pigment and that of the medium Zinc 2.37 Oxidizing soya alkyd 1.52–1.53 in which it is dispersed, the greater the Titanium dioxide (anatase) 2.55 Styrene butadiene resin 1.53 refractive light scattering. Titanium dioxide (rutile) 2.73 Alkyd/melamine (75/25) 1.55

Speed‑of‑light‑in‑vacuum Refractive Index= Speed‑of‑light‑in‑substance

Figure 5

Reflectance of TiO2 Pigment in Various Regions of the Spectrum

100 90 80 70 60 50 40

Percent reflectance Percent 30 Visible 20 10 0 300 400 500 600 700 800 900 1000

Anatase Wavelength (nm) Rutile

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Figure 6 Figure 6 shows a practical Effect of Refractive Index on Opacity demonstration of the effect of refractive index on opacity. The films were formulated at constant volume percent Clay Calcium Carbonate Anatase TiO Rutile TiO 2 2 pigment in an acrylic vehicle. The film

made with rutile TiO2 does the most complete job of hiding the substrate.

TiO2 Particle Size As has been previously covered, for

most efficient light scattering, the TiO2 R.I. 1.65 1.63 2.02 2.55 2.73 pigment diameter should be slightly less than one-half the wavelength of light to be scattered. Since the human eye Figure 7 is most sensitive to yellow-green light (wavelength about 0.55 microns), the Relative Light Scattering Power versus Rutile Particle Size theoretical optimum particle size for

TiO2 pigments for coatings is between 1.75 0.2 and 0.3 microns in diameter.

1.50 Studies by microscopy have confirmed this range for the primary particle 1.25 size. However, different measurement 1.00 technologies can give different results.

0.75 Scattering Power Blue 0.50 Curves in Figure 7 derived from

Relative scattering power Green 0.25 theoretical considerations in highly Red dilute systems show the relative 0 scattering power of rutile TiO for blue, 0.05 0.10 0.15 0.20 0.30 0.50 0.80 2 Diameter (microns) green and red light as a function of particle size. At about 0.2 microns, the sum of light scattered at all wavelengths is maximized. When the particle size is increased to between 0.25 and 0.30 microns, the scattering of blue light decreases rapidly, but the scattering of green and red is relatively unchanged; however, at 0.15 microns, the diameter corresponding to maximum scattering of blue light, light scattering in the red and green regions drops markedly.

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Undertone Figure 8 In an ideal white film that is pigmented to Scattering of Light by White Paint complete hiding, changing pigment particle Incident Light: Equal parts of short and long wavelength (blue and red) size has no effect on color since all the light Incident Light: Equal parts of short and long wavelength (blue and red) striking the film is completely scattered. This is illustrated in Figure 8 which shows White Paint Film that both blue light with the shortest path length and red light with the longest are both totally reflected—the visual effect is the same as if all light had the same path length. Figure 9 illustrates the case in which an absorbing pigment such as black is added to the white paint formula. On one hand, smaller particles scatter blue light more efficiently than the red light (see Fig. 7). That means shorter path/less absorption SUBSTRATE for the blue light. On the other hand, red White pigment particles light with the longer path length now has Reflected light short λ (blue) a greater chance to be absorbed. As a Reflected light long λ (red) consequence, the reflected hue appears bluer. Thus, in a paint film containing some light-absorbing matter, decreasing TiO2 particle size will increase blueness. This Figure 9 phenomenon is called undertone. Scattering and Absorption of Light by Gray Paint

Pigment Volume Concentration (PVC) Incident Light: Equal parts of short and long wavelength (blue and red) Coatings properties such as gloss, Incident Light: Equal parts of short and long wavelength (blue and red) permeability, porosity, hiding power, tinting strength and undertone are directly Gray Paint Film related to PVC. A dry paint film is a three- dimensional structure and as such the volume relationships among its components will bear importantly on paint performance.

Pigment volume (TiO + extenders) % PVC = 2 X 100 Pigment volume + volume of binders

PVC is the ratio, by volume, of all pigments in the paint to total nonvolatiles. SUBSTRATE

At a particular PVC called the critical White pigment particles pigment volume concentration (CPVC), Black pigment particles in white paint many physical and optical properties of Reflected light short λ (blue) Reflected light long (red) paint change abruptly. Generally, CPVC λ is considered to be the PVC where there is just sufficient binder to coat pigment surfaces and provide a continuous phase throughout the film.

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Figure 10 Dry Flat Hiding

Constant TiO2 Spreading Rate (per unit area of dry film) Interestingly, as air is incorporated into a paint film as a result of formulating highly pigmented coatings above the CPVC, the average refractive index of the vehicle matrix decreases, increasing the refractive index difference between the pigment and surrounding medium. The result is increased light scattering. Formulators often use dry flat hiding to scattering efficiency 2 improve hiding of low-gloss flat interior TiO architectural finishes.

Scattering Efficiency and Coating

TiO2 volume concentration Opacity

As the TiO2 PVC or TiO2 volume

concentration (volume ratio of TiO2 in the paint to total nonvolatiles) increases above approximately 10%, diffractive light scattering decreases

because of TiO2 particle crowding. The result of this effect can be shown by Figure 11 formulating a series of coatings with

Constant Dry Film Thickness increasing TiO2 volume content, but

at constant TiO2 per unit area of the dry film (decreasing film thickness). This is illustrated in Figure 10. On the

other hand, an increase in TiO2 volume concentration at equal film thickness will initially show an increase in total opacity of the coating (despite the loss in efficiency) up to about 30 PVC, and

Total film hiding (SX) Total then hiding or opacity decreases with

CPVC further additions of TiO2 because the scattering efficiency is falling more rapidly than compensated for by higher

TiO2 volume concentration TiO2 concentration. This continues until the CPVC is reached, at which point the onset of dry flat hiding causes opacity to increase again (Figure 11).

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TiO2 Surface Treatment Table 2

One way to prevent crowding of TiO2 particles in highly pigmented systems Some Causes of Undesirable Color Effect is to coat the pigment surface in 1. Contamination—including abraded processing equipment, usually resulting from problems during the a controlled manner. The surface dispersion process. coating then acts as a physical spacer, maintaining separation between 2. Colored products of reactions of TiO with other paint ingredients such as phenolics, strong reducing adjacent TiO2 particles and minimizing 2 losses in diffractive light-scattering agents, etc. efficiency as pigment concentration is increased. A unit weight of this specially 3. Blue, purple or gray discoloration in -impermeable films exposed to ultraviolet radiation. coated pigment contains less TiO2 than its uncoated counterparts, but the light- scattering ability of the heavily coated 4. Excessive heat exposure—vehicle discoloration. grade is higher in most high-PVC paints.

Color, Particle Size, and PVC 5. Inadequate hiding—show-through of substrate. Color and undertone are sometimes confused. It is possible for a paint containing blue undertone TiO2 to have a yellow color because of one of the undesirable effects listed in Table 2. Blue and yellow undertone pigments will have equal color or brightness when measured in pure white coating formulas at complete opacity. Figure 12 Probably more color-matching Titanium Dioxide Effect of Particle Size and PVC on Tinted Paint Undertone problems result from the use of the wrong particle-size TiO2 and/or failure to recognize undertone changes that occur with TiO2 concentration than from improper combinations of colored 20 pigments. The combined effects of particle size and TiO2 PVC on the color of a tinted paint are substantial and are shown in Figure 12. The decrease 10 in scattering efficiency as TiO2 PVC PVC % increases occurs to the greatest extent in the red part of the spectrum; hence, reflected light shifts to the blue region as PVC increases. 5

Fine Medium Coarse Particle Size

*Blue/red reflectance values 10 Ti-Pure™ Titanium Dioxide


Extenders Hiding Power and Tinting Strength hitting it. Coating C is a white coating but is at incomplete hiding. Some of In addition to TiO2 and vehicle, many Hiding power and tinting strength are paints also contain extender pigments. two optical properties used to describe the light hitting it penetrates through These normally low-cost materials the light-scattering efficiency of a to the black substrate and is absorbed perform a variety of functions. White white pigment, and must be considered while the rest is scattered. This coating extender pigments are when selecting a commercial grade therefore appears gray. compounds of relatively low refractive of TiO2. The hiding power of a paint is While hiding power is a measure of the index. They differ in composition, size a measure of its ability to obscure a ability of TiO2 to opacify a white paint and shape. White extender pigments background of contrasting color, and film, tinting strength describes its ability develop very little hiding in gloss and results from interactions between to add whiteness and brightness to semigloss paints, but they contribute incident light and the pigments present the color of a tinted paint. The tinting dry-flat hiding (air-pigment interface) in the paint film. White pigments provide strength test describes TiO2 light- to paints at low cost and are used to opacity by scattering incident visible scattering contribution relative to the control gloss, texture, suspension, and light at all wavelengths, and color light-absorbing ability of a colored viscosity. The main types of extenders pigments provide opacity by absorbing pigment when a white paint is tinted to are , silicates, sulfates, and incident visible light at characteristic about 50% reflectance with the colored . Their particle sizes range from wavelengths. Figure 13 illustrates two pigment. To be sure that flocculation 0.01 to 44 microns. Often more than coatings (A and B) at complete hiding does not give misleading tinting one extender is used to obtain optimum and one coating (C) at incomplete hiding, strength results, the tinting strength properties. A high-gloss white paint all covering a black substrate. Coating measurement should be accompanied usually contains only TiO2; a semigloss A is pure white and reflects or scatters by some measure of flocculation such paint contains TiO2 and some extender all the light hitting it before any of the as a rub-up test on the partially dried pigments; a flat paint contains TiO2 but light reaches the substrate. Coating B tinted paint. has a high extender content. is pure black and absorbs all the light

Figure 13 Opacification of a Film

A: Complete Hiding—Light Scattering B: Complete Hiding—Light Absorption C: Incomplete Hiding

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Color of dry TiO2 and white paints include or 85 degrees as measured from brightness (measured either as Hunter perpendicular. We speak of 20-degree Dry compacted TiO2 samples are characterized by their brightness and green filter reflectance G, or as CIE Y gloss for the highest-gloss surfaces, whiteness, and exhibit reflectance tristimulus value) and yellowness index 60-degree for low-gloss and semigloss properties approaching that of the as shown below: paints, and typically reserve 85-degree perfect reflecting diffuser. “Color” is gloss for eggshell and flat paints. Yellowness Index (Y.I.) by ASTM D1925 carefully controlled during the TiO 2 The gloss of a coating is primarily manufacturing process through the A B (Amber reflectance) — (Blue reflectance) determined by PVC, pigment type and removal of trace amounts of Y.I. = X 100 G vehicle type. Within a specific formula, oxide contaminants. These light- TiO selection is important because OR 2 absorbing contaminants will detract the gloss will be negatively affected from the brightness and whiteness (1.28X — 1.06Z) Y.I. = X 100 by exceedingly large fraction of hard, Y of the pigment, and can affect the unground agglomerates in the paint. appearance of white and near-white A, B and G = Hunter or Gardner Reflectometer Reflectances Therefore, the fraction of particles larger paints containing that pigment. The TiO (tristimulus colorimeter readings, normalized to 100) 2 X, Y and Z = CIE Tristimulus Values, 2° Standard Observer, than a certain diameter (dependent upon Illuminant C present in a white paint contributes to the system) is an excellent predictor the color of the paint film by scattering of gloss. Proper TiO grade selection, Gloss 2 light and providing brightness, correct formulation and procedures to whiteness, and opacity. However, Of all the optical properties of a maximize dispersion are needed. Also, there are many circumstances which coating, the perception of gloss is finishes are subjected to a variety of can cause undesirable color effects the most complex. Analysis of visual conditions during manufacture, storage, in a white paint film; some have been gloss observations reveals that several application, curing and use that can shown in Table 2. As described earlier, criteria are involved in the psychology of affect final gloss. Table 3 lists some of the appearance of a nonabsorbing gloss: these factors. white paint film at complete hiding • Specular reflectance is unaffected by TiO particle size or 2 • Distinctness of image (eyes focused undertone. on virtual image behind surface) The color of dry TiO and white 2 • The contrast between light and dark (and near-white) paint films is often images expressed in terms of their CIE L*a*b* • Haze color coordinates (10° Standard Observer, Illuminant D65), wherein Of these, specular reflectance has L* is a measure of brightness, a* is a proved the most popular for widespread measure of redness-greenness and b* analytical evaluation of the surface a measure of yellowness-blueness. CIE phenomena we call gloss. This is color difference values such as L* and typically measured as the amount of b* are also used to describe the color light reflected off a surface at an angle of a sample relative to an agreed-upon equal to a beam of carefully focused reference sample. Other commonly incident light. Most gloss evaluations used expressions to describe the color are performed at angles of 20, 60

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Table 3 Dispersion

The particle size of TiO2 is small Some Factors Affecting Gloss compared to the thickness of the film in Manufacture which it is used. As discussed in “Optical

Fineness of grind Theory” (p. 7), TiO2 has a theoretical Type of mill optimum particle size between 0.2 Raw materials and 0.3 microns, but as received is Ratio of pigment to binder considerably larger because of the formation of agglomerates in handling Storage during the manufacturing process. The Gradual wetting of pigment energy of simply stirring pigment into Poor reincorporation of settled coarse particles water or binder is not great enough Seeding, soap or crystal formation to overcome the particle attractive Gradual increase of viscosity forces preventing the breakup of the Application agglomerates. By not minimizing the Smoothness of substrate number of these agglomerates, the Loss of binder into substrate end-use properties will all be adversely Dissolving of binder from priming coat affected (e.g., gloss, hiding power, Varying degrees of shear during application tint strength, poor suspension, color Various degrees of leveling or flow resulting from the particular method streaking in tints and grit in the film). of application (e.g., orange peel on spraying) Although the pigment is designed to Contamination with dust yield optimum hiding power, gloss and Film thickness color, these basic properties may not be Rate of loss (e.g., flash time before baking) realized if the initial dispersion of TiO is Baking temperature and time 2 inadequate. Figure 14 shows the particle Humidity during drying size distribution of a poorly dispersed Use pigment versus a well-dispersed pigment. Variation with age of film and conditions of exposure The optimum dispersion for the pigment is defined where further grinding will not change this distribution.

Figure 14 The actual process of breaking agglomerates (i.e., dispersion) can be TiO2 Dispersion States vs. Particle Size Distribution and Pigment Properties visualized as occurring in three steps in the grinding process: 1. Wetting, where air and other substances are displaced from Film properties Gloss the pigment surface by solvent, dispersant/surfactant and binder. Degree of dispersion 2. Grinding, in which the agglomerates of pigment particles are broken and Volume fraction % fraction Volume separated into an optimum particle Optical properties distribution. Hiding power Tinting strength 3. Stabilization, by which the optimally separated particles are maintained by 0.1 0.2 0.5 1.0 2 5 10 20 30 40 50 either charge or steric stabilization. Well dispersed Diameter (microns) 7½ 7 6 5 4 Poorly dispersed Hegman fineness

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This classification is useful because Figure 15 Flocculation our experience shows that one pigment Dispersion Process Flocculation is the formation of loose may differ from another in one or clumps of TiO2 particles (i.e., flocculates) more of these steps of the dispersion in a fluid system. Flocculation is process. However, the three phases are often the result of an inadequate not always taken into consideration by initial grind (dispersion), improper pigment users; consequently, a pigment type or concentration of dispersant, is frequently described simply as “poor pH mismatch, and temperature. in dispersion properties” regardless of Characteristically, these clumps are the specific phase in which it is actually easily broken under moderate shear, but deficient. Figure 15 visually illustrates Wetting will quickly reform if the particles are (Solvent) this concept. free to move in the matrix. Flocculation can cause several major problems, TiO2 dispersion in oleoresinous binders (i.e., solvent-based paints) usually including: depends on shear rate, mill • Loss of opacity and tinting strength— viscosity, time and degree of wetting flocculates do not scatter as provided by the vehicle. Although the efficiently as primary TiO2 particles. resin is often the sole dispersing agent, • Excessive viscosity and poor there are dispersants formulated for flowability—often, stirring will thin the specific resins and solvent systems. suspension, but flocculation will recur on standing. In water systems, dispersants are Particle Separation (Mechanical Energy) required for wetting and stabilization. • Low gloss. It is important to recognize that both Weatherability amount and type of dispersant affect dispersion quality. Excess dispersant Weatherability is a term applied to the is self-defeating, particularly with various changes in appearance and ionic types, and should be avoided. functional value of exposed pigmented The optimum amount varies with the coatings. It includes all parameters of exterior serviceability, such as retention particular dispersant used, the TiO2 grade and water hardness. A very simple of color, retention of gloss, chalking, test for determining dispersant demand adhesion (blistering, flaking, peeling) and involves measuring the Brookfield film integrity (i.e., checking, , viscosity of a 70 weight-percent Stabilization erosion, protection). These Flocculation (dispersant) performance properties are controlled TiO2 aqueous slurry prepared using a high-speed disperser and several principally by formulation (e.g., choice different dispersant concentrations. of vehicle, extender, pigment volume The optimum dispersant concentration concentration, etc., which are relatively yields minimum viscosity. Using independent of the grade of TiO2 used). dispersant at this level, pigment However, chalk resistance, retention concentration can be varied to achieve of color (tinted paints) and gloss, and desired mill base rheology. Dispersant resistance to discoloration by mildew selection is even more critical in paints and dirt collection can be influenced by utilizing anionic and nonionic rheology TiO2 grade selection. modifiers. White pigment particles

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Figure 16 high-molecular-weight . Gloss Retention and Chalk Resistance Florida Exposure Series These polymers are susceptible to (Blue-tinted Architectural Alkyd at 15PVC) photochemical attack, and degrade over time to form low-molecular-weight Gloss Retention oxygenated species that solubilize and 100 wash from the surface of the film. This 90 process increases surface roughness 80 and reduces gloss. Chalking occurs as 70 60 increased amounts of organic binder are 50 removed from the surface of the film, 40 causing TiO2 and extender pigments 60° washed gloss washed 60° 30 to protrude through the film surface 20 producing a white, chalky appearance. 10 Chalking in tinted paints is a particular 0 0 5 10 15 20 25 concern, since its onset causes color

Pigment A Exposure time (months) change—increased lightness and Pigment B reduced chromaticity. In this regard, the most chalk-resistant pigments are essential for best color and gloss Chalk Resistance retention in tinted paints. For example, 0.25 Figure 16 illustrates the improvements

0.20 in gloss retention and chalk resistance in a blue-tinted architectural alkyd that 0.15 can be obtained through selection

of a durable TiO2 grade. As shown in 0.10

Red reflectance the upper graph, the paint containing

0.05 Pigment B exhibits higher 60° washed gloss over the exposure period than 0 the paint containing Pigment A. 0 5 10 15 20 25 Similarly, the lower graph shows the Pigment A Exposure time (months) paint containing Pigment B to be more Pigment B resistant to chalking than the paint containing Pigment A. In this case, the The weatherability of pigmented assessment of exterior performance; degree of chalking is determined by coatings is best evaluated through however, reliability of this testing is measuring the red reflectance, wherein exterior exposure studies over a range such that results need to be confirmed increased reflectance is due to the of representative climate conditions. through exterior exposure experiments. increased levels of white pigment Frequently, test panels are placed protruding through the surface of the Chalk Resistance and Gloss Retention on exposure at locations like Florida, film. Arizona, and Australia to measure The initial effects of Rutile TiO is inherently more chalk- performance under extreme conditions. are usually detected at the surface 2 resistant than anatase because it Appearance and film properties can be of the paint film and are caused by absorbs significantly more UV-A monitored over the expected service degradation of the organic binder ultraviolet radiation in the region of of the coating. Use of accelerated on exposure to sunlight, moisture, 350–400 nanometers (Figure 5, testing equipment to simulate exterior temperature change and environmental page 7), converting it into energy in exposure is frequently used within the pollutants. The organic binders coatings industry to obtain a preliminary used in coatings applications are

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Figure 17 the form of heat and protecting the demanding high initial haze-free gloss organic portions of the paint film from and a high degree of gloss retention Impervious Shell of SiO2 on Pigment Surface UV degradation. The surface of the over the service life of the coating,

TiO2 pigment particle is, however, selection of a TiO2 grade with high gloss photochemically active and can, in and durability, like TS-6200, is critical to

the presence of H2O and O2, promote a successful formulation. These types degradation of the organic binder of pigments are required to complement at the pigment surface. This form the performance of photochemically of degradation can be controlled stabilized vehicle systems used in a through the application of inorganic range of high-performance architectural oxide surface treatments, which act and industrial coatings systems. as barriers between the TiO surface 2 Occasionally, pigment chalking is and the organic binder. Ti-Pure™ Select desired. If “cleanup” of dirt (e.g., white TS-6200 and R-960 are outstanding house paints) is desired, the formulator commercial examples, wherein each may do the following: pigment particle is encased in an impervious shell of SiO . This tight • Increase pigment volume 2 concentration. SiO2 coating provides a high degree of protection against photochemical • Use a less chalk-resistant grade of rutile or extender. activity. The SiO2 surface treatment is shown in Figure 17. For applications • Use some anatase in combination requiring maximum chalk resistance with the rutile pigment. and tint retention, Ti-Pure™ R-960 and However, use of these methods will TS-6200 are the preferred grade. The decrease tint and gloss retention. ­relative chalk resistance of several Ti-Pure™ titanium dioxide grades is ­illustrated in Figure 18. For applications Figure 18

Chalk Resistance of Ti-Pure™ Pigments

R-900 R-902+ R-706 R-960 TS-6200

13 Months Exterior 17 Months Exterior 33 Months Exterior 35 Months Exterior 42 Months Exterior Exposure Exposure Exposure Exposure Exposure 16 Ti-Pure™ Titanium Dioxide


Standard Classifications

Table 4 identifies paint grade Ti-Pure™ titanium dioxide pigments conforming to each of the four types specified in ASTM D476 classifications.

Table 4

ASTM Specification for Paint Grade Ti-Pure™ Titanum Dioxide Pigments

ASTM Type I Type II Type III Type IV Type V Type VI Type VII Standards Anatase*— Rutile— Rutile— Rutile— Rutile— Rutile— Rutile— D 3720 free chalking low-medium medium high high medium-high medium-high chalk resistance chalk resistance chalk resistance chalk resistance chalk resistance chalk resistance

Exterior coatings Exterior coatings Interior–exterior Interior–exterior White exterior requiring Typical end-use Low-medium requiring coatings coatings house paint and High percent PVC excellent application(s) percent PVC excellent medium–high low–high interior uses durability with durability percent PVC percent PVC high gloss

Titanium dioxide (Ti0 ) 2 94 92 80 80 90 90 92 D 1394 content, min, percent

Specific resistance, 5000 5000 3000 3000 3000 5000 5000 D 2448 min, Ω

Moisture content as 0.7 0.7 1.5 1.5 1 0.7 0.7 D 280 packed, min, percent

Specific gravity 3.8–4.0 4.0–4.3 3.6–4.3 3.6–4.3 3.6–4.3 3.6–4.3 4.0–4.3 D 153

45-µm screen residue, 0.1 0.1 0.1 0.1 0.1 0.1 0.1 D 185 max, percent

Type I Anatase

Type II Rutile — low-medium chalk resistance — R-706, R-900, R-902+

Type III Rutile — medium chalk resistance — R-706, R-902+, TS-6300**

Type IV Rutile — highly chalk resistant — R-706, R-960, TS-6200

Type V Rutile — exterior applications with high gloss — R-706, TS-6200

Type VI Rutile — interior exterior, medium-high PVC — R-706, R-902+

Type VII Rutile—interior exterior, low-high PVC—R-706, R-902+

* Identification of anatase or rutile or mixtures therof is made by X-ray analysis (Test Method D 3720). ** Preferred Ti-Pure® grade for high PVC flat finishes.

17 Ti-Pure™ Titanium Dioxide


Interior Architectural Paints clean colors in tinted systems with Gloss and Semigloss Paints R-706 providing a blue undertone and R-902+ providing a more neutral Ti-Pure™ R-900 is recommended for undertone. general use in alkyd and latex paints for interior gloss and semi-gloss For paint manufacturers capable of applications. This pigment disperses handling TiO2 in aqueous slurry form, easily, develops high gloss and shows Ti-Pure™ R-706 and R-902+ are maximum hiding power over a wide available as slurry grades,Ti-Pure™ range of gloss grade applications. R-746 and R-942 respectively.

Two multipurpose gloss Flat Paints grades, Ti-Pure™ R-706 and Ti-Pure™ These coatings are formulated at R-902+, are recommended for use relatively high levels of extenders and when a single pigment is required to TiO pigments, and are frequently perform well in both interior and exterior 2 above the critical PVC for interior gloss and semi-gloss systems. R-706 applications. Ti-Pure™ Select TS-6300 is the ideal selection for applications is recommended for these applications. requiring high gloss, maximum gloss Because it is a highly surface-treated retention and chalk resistance. Both TiO grade, TS-6300 will provide R-706 and R-902+ will deliver bright, 2 superior performance in this class of highly crowded paint systems.

18 Ti-Pure™ Titanium Dioxide


Exterior Architectural Paints retention. Ti-Pure™ R-706 is the ideal is used primarily to provide hiding or opacity, but grade selection can also In addition to normal criteria, selection choice for emulsion trim paints because it provides maximum initial gloss and have a significant effect on coating of the proper Ti-Pure™ titanium dioxide gloss, exterior durability and, for - grade for these coatings will depend outstanding exterior durability. These last catalyzed coatings, film cure. The TiO upon the desired balance between two properties result from lower PVC 2 grade most appropriate for a particular gloss and tint retention, self-cleaning and generally better binder durability application depends on the end-use ability, and prevailing atmospheric associated with exterior emulsion trim coating properties it affects. conditions. For high gloss and maximum paints. Ti-Pure™ R-902+ also satisfies exterior durability in architectural these requirements over a wide range of Automotive OEM and Refinish solvent-based and aqueous systems. coatings systems, Ti-Pure™ R-706 is Coatings recommended. Ti-Pure™ R-902+ is also Ti-Pure™ Select TS-6300 performs Automotive coatings are among the highly chalk resistant; it performs well well in selected exterior white latex most demanding applications for TiO2 over a wide range of solvent-based and house paints, following reformulation pigments. Proper selection of pigment aqueous systems where tint retention to accommodate the higher surface grades is critical to optimize: is important. Both R-706 and R-902+ area of the pigment, and to maintain • Manufacturing and application will deliver bright, clean colors in tinted film integrity. When exterior durability processes. systems with R-706 providing a blue is desired in a flat paint, R-902+ is also • Mechanical and chemical integrity. undertone and R-902+ providing a highly recommended. more neutral undertone. Ti-Pure™ R-900 • Aesthetics, which are required for has medium chalk resistance and is Industrial Finishes today’s automotive coating systems. preferred when dirt collection is a Industrial finishes include a variety of Several Ti-Pure™ grades are available problem. These pigments can be used in market subsegments such as automotive for automotive coating applications, both alkyd and emulsion paints. finishes, powder coatings, coil and offering both Original Equipment Tinted house paints and both white can coatings, and maintenance paints. Manufacturers (OEMs) and refinish and tinted trim paints require a high Each has substantially different quality formulators a selection of the desired degree of chalk resistance and gloss and performance requirements. TiO2 combination of properties.

19 Ti-Pure™ Titanium Dioxide


Electrodeposition Primers: performance. The fast wet-in and easy Flow and Optics: Ti-Pure™ R-706 Ti-Pure™ R-900 is ideally suited for dispersion properties of TS-6200 provides easy dispersion, high-cure electrodeposition applications. can provide increased throughput in flowability (which yields decorative R-900 provides easy dispersion, manufacturing operations. coatings of high gloss and reflectance) excellent hiding, high resistivity, and and increased opacity. These properties Powder Coatings low soluble content that provides combined with high durability excellent application properties and The continuing emergence of powder performance make R-706 suitable for high corrosion resistance. coatings as a significant and high- both interior and exterior use. growth market segment has led to the Topcoats: TS-6200 combines high development of thousands of specific Durability: TS-6200 is the most gloss and distinctness of image with formulations from only a handful of durable Ti-Pure™ pigment available and excellent resistance to weathering for primary resin/crosslinking systems. is suggested for use in systems such high-quality OEM and refinish topcoats. Technological advances have been as triglycidyl isocyanurate (TGIC) and TS-6200 and R-960 are the most based primarily on developments Primid cured polyesters where outdoor durable Ti-Pure™ pigments available, and improved understandings in resin weatherability is of primary concern. making them also ideal for OEM and chemistry. Recently, the influence of Overbake Yellowing Resistance: Both refinish applications. TiO2 in powder coating systems has Ti-Pure™ R-960 and R-900 provide Processing: Optimization of optical and been explored, allowing formulators to excellent resistance to overbake mechanical properties of an automotive select pigments with varying chemical yellowing during cure. coating depends on properly dispersed and physical properties. Several pigment. Choosing a pigment that is Ti-Pure™ grades are available to optimize ideally suited for each coating system processing and end-use performance of is critical to maximizing coating specific powder formulations.

20 Ti-Pure™ Titanium Dioxide


Other Industrials gloss and excellent exterior durability implement and transportation finishes, unique in the industry. It can be used and some container coatings. All Ti-Pure™ grades are commonly in both interior and exterior coatings used in industrial coatings. The Ti-Pure™ R-900 is used primarily for where this combination of gloss and performance differences in these interior coating applications. Ti-Pure™ durability combined with excellent grades are determined by their surface R-900 is widely used for can coatings dispersibility is of value. Applications treatment, particle size and particle- where its neutral undertone and high include coil coatings for residential size distribution. Silica provides exterior gloss are valued. Other applications aluminum siding and architectural durability (chalk resistance and gloss include appliance coatings, metal building panels, aerospace coatings retention). Alumina provides ease of furniture finishes and high-reflectance and other high-durability applications. dispersion and flocculation resistance. white coil coatings. Smaller particle size, narrower particle Because of the silica surface treatment, size distribution and smaller particle TS-6200 provides better film cure in coarse tail contribute to the superior acid-catalyzed coatings than non-silica- gloss of R-706. Although high hiding is treated grades. important in all coatings, grade choice Ti-Pure™ R-902+ is used in high-quality often depends on the level of gloss and finishes that require very good chalk exterior durability required. resistance and gloss retention, but not the exceptional performance provided Ti-Pure™ Select TS-6200 is the most widely applicable grade, possessing by R-706 and TS-6200. This grade is a combination of exceptionally high often used in industrial maintenance,

21 Ti-Pure™ Titanium Dioxide


Product Manufacture Titanium dioxide pigments are made by two commercial processes—sulfate and chloride. Both anatase and rutile can be produced by either process. The chloride process has become the dominant process because it produces a superior pigment with significantly fewer waste products. Chemours operates only chloride process .

The flow charts in Figure 19 illustrate, in simplified form, the two processing routes to intermediate TiO2 products. The lower part of Figure 19 illustrates finishing operations, which are the same for either manufacturing method.

The sulfate method was commercialized Figure 19 in 1931, producing anatase TiO2 and TiO2 Manufacturing Processes later (1941) rutile TiO2. In this process, containing titanium is dissolved SULFATE in , yielding a of Titanium Ore H2SO4 titanium, and other metal sulfates. Then, through a series of steps including Filtration and chemical reduction, purification, Solution Precipitation Washing precipitation, washing and calcination, pigmentary-size intermediate TiO2 is Ferrous Sulfate Intermediate TiO produced. The , anatase 2 or rutile, is controlled by nucleation and calcination. CHLORIDE ➞ FeTiO3 + 2 H2SO4 TiOSO4 + FeSO4 + 2 H2O ➞ Titanium Ore Carbon Oxygen TiOSO4 + H2O TiO2 + H2SO4

The chloride method was commercial- ized by DuPont in the 1950s to produce Chlorination Purification Oxidation Intermediate TiO2 rutile TiO2 and is now owned by the

Chemours Company. This process Chlorides includes high-temperature, anhydrous of other than Titanium vapor phase reactions. Titanium ore is reacted with chlorine under FINISHING reducing conditions to obtain titanium Intermediate Surface Filtration Grinding Packing TiO2 Modification Washing and Drying tetrachloride (TiCl4) and metallic chloride , which are subsequently removed. Additives

Finishing Slurry Makeup Loading and Slurry Storage Shipping

22 Ti-Pure™ Titanium Dioxide


Highly purified TiCl4 is then oxidized at high temperature to produce intermediate TiO2 of excellent brightness. The oxidation step in the chloride process permits close control of particle size distribution and crystal type, making it possible to produce TiO2 with high hiding power and tinting strength.

➞ 2 FeTiO3 + 7 Cl2 + 3 C 2 TiCl4 + 2 FeCl3 + 3 CO2 ➞ TiCl4 + O2 TiO2 + 2 Cl2

The worldwide capacity to produce pigment by the chloride process is now greater than the sulfate capacity and continues to grow. In both sulfate and chloride processes, intermediate products are clusters of TiO2 crystals of pigmentary size which must be separated (ground) for optimum optical performance.

Figure 20

TiO2 Surface Treatments

R-900 R-902+ R-960 TS-6300 Interior Interior/Exterior Exterior Flat Grade


Amorphous SiO2: durability

Engineered SiO2 / Al2O3 for optimal spacing

Amorphous Al2O3: durability

R-706 TS-6200 Cristalline Al2O3: dispersability Universal Superdurable Interior/Exterior Exterior Organic: flow & wetting 23 Ti-Pure™ Titanium Dioxide


Depending on end-use requirements, nature at low concentration. Efficient Quality Assurance in Product Design various wet processing methods are mining and In order to ensure that new products used to modify the TiO , including operations are required to develop a 2 are designed to meet the changing precipitation of hydrous oxides such viable ore supply meeting the economic needs of our customers, Chemours as silica and alumina on the pigment requirements for TiO manufacture. 2 employs a product development particle surface. Individual hydrous oxide Chemours has extensive operations methodology called Product And treatments or various combinations can worldwide to ensure a continuing Cycle-Time Excellence (PACE). This be used to optimize performance for supply of economic titanium- multiphased process prescribes the key specific applications. bearing concentrate to our several to a successful product development manufacturing sites. Crucial to the manufacture of titanium effort from concept through commercial dioxide pigments is the supply of Chemours titanium dioxide reality. By recognizing customer needs titanium ore. Although titanium manufacturing facilities are located and focusing resources to meet those ranks among the top ten elements in around the world to best meet your needs, quality is designed into Ti-Pure™ abundance, it is widely distributed in supply needs (Figure 21). pigments.

24 Ti-Pure™ Titanium Dioxide


Table 5 Table 6

Important laboratory tests are: Checklist: Bag TiO2 versus Slurry — Potential Savings • Particle size distribution using a laser- light-scattering technique. Bag handling cost Quality control Unload and transfer to storage TiO errors eliminated • X-ray fluorescence analysis for 2 Uniform batch-to-batch dispersion precise process control of surface Deliver to process area treatments. Charge process Uniform quality Remove bags and pallets • Dispersion as measured by Hegman Inventory control fineness of an alkyd mill base or by TiO losses Eliminate counting errors screening technique for aqueous 2 Warehouse—broken bags Running total—lbs in versus lbs out dispersion. Process spillage and dust Batch totals—cumulative • Dry color of a compressed TiO 2 Left in bag—¼ to ½ lb/bag pigment in CIE L*a*b* color space. Process utilization Faster TiO charge time • pH and resistance of 20% aqueous Waste disposal cost 2 dispersions. Bags Optimize batch size—eliminate 50 lb Pallets increments • Carbon black undertone, blue/red Increase throughout—no dispersion required reflectance ratio of a mulled mixture Storage cost of 20 parts TiO to 1 part carbon 2 Bag TiO Safety and housekeeping black in oil. 2 Cleaner work area—no dust and spillage Slurry TiO2 • Oil absorption, a spatula rubout Eliminate exposure to forklift/hand truck hazards linseed oil test similar to ASTM D281-31.

25 Ti-Pure™ Titanium Dioxide


Quality Assurance in Product SPC provides fast response for In all laboratory test operations, we Manufacture more consistent on-aim operation. employ a rigorous intra-laboratory Chemours has long recognized that Chemours also uses process capability cross-check program and statistical manufacturing process control has a analysis (Cpk and Ppk) and Six Sigma process control for monitoring methods direct bearing on the product’s fitness Methodology to drive continuous to ensure the consistency of Ti-Pure™ improvement. TiO performance data. Finally, all of our for use. For these reasons, we employ 2 manufacturing sites, customer service the most sophisticated process control In our laboratories, we measure the operations and supply chain operations technology available. Ti-Pure™ TiO performance opposite 2 maintain quality systems registered to our understanding of customer needs, Chemours is a pioneer in the use ISO 9001. In this way, the customer is determine if product is fit for use and of cumulative sum statistical assured of unmatched reliability and control our manufacturing process process control (CUSUM). CUSUM consistency regarding titanium dioxide supply.

Figure 21 Ti-Pure™ Facilities

Kallo, Belgium

Wilmington, Delaware New Johnsonville, Tennessee Delisle, Mississippi

Altamira, Mexico Mexico City, Mexico Barra Mansa, Brazil


Manufacturing Facilities Technical Service Laboratories

26 Both Manufacturing and Technical Service Ti-Pure™ Titanium Dioxide


Product Packaging and Delivery system savings achieved. Additional support your individual formulation information about TiO slurries and needs, our technical service Ti-Pure™ titanium dioxide dry pigments 2 laboratories are fully equipped to are available in 25-kg bags slurry facilities can be obtained by ™ assist you (Figure 20). and 1-tonne flexible intermediate contacting your local Ti-Pure sales representative. bulk containers. Ti-Pure™ bulk bags, Samples/Order Placement often called semi-bulk containers, are Technical Service available in one-tonne sizes. In some Samples of dry and slurry locations, dry bulk truckload quantities In addition to the products and Ti-Pure™ titanium dioxide grades are available. packages we offer, our commitment are readily available from to customers includes having www.titnaium.chemours.com and are In certain regions of the world, aqueous accessible and knowledgeable sales recommended for your use in product slurries of several grades of TiO are 2 and technical service representatives development and testing. To place available via railcar and tank truck. to help determine which elements of an order, please contact your local Slurry handling facilities are relatively our offerings best meet your needs. To representative. simple and are frequently justified by

Shanghai, China, Kuan Yin, Taiwan


Manufacturing Facilities Technical Service Laboratories

Both Manufacturing and Technical Service 27 Ti-Pure™ Titanium Dioxide


A new kind of chemistry company Chemours will develop innovative Chemours sustainability goals include: for a world that demands more. to meet growing market needs • Making significant progress to while making specific contributions to We rely on chemistry every day. It becoming carbon positive by 2050. the 2030 United Nations Sustainable is the essential science of modern Development Goals (UNSDGs). • Cutting the intensity of our life. It keeps our homes cool, our emissions by 60%. fresh, and our families safe. It That means supplying the materials keeps our cars and airplanes running that help engines become more fuel • Improving water quality, ensuring a and fuel efficient and our world efficient; providing coatings that 99% reduction in fluorinated organic vibrant, clean, and connected. help keep cities cool; inventing new compound emissions to air and water. refrigerants that don’t harm the Today, chemistry must do more. We're encouraging our suppliers to layer or warm the planet; and Chemistry needs to be as responsible be more responsible throughout their enabling new technology such as 5G as it is essential, even as it offers businesses and choosing to do business communications and the internet of more comprehensive solutions with those that align with our values. things to better connect the world. than it ever has before. We are We have a responsibility to our world, committed to delivering world-class customers, consumers, investors, and technology that solves problems to the essential science on which we without creating new ones. all depend. Learn more at https://www. chemours.com/our-company/corporate- responsibility/ .

28 Ti-Pure™ Titanium Dioxide

29 The information set forth herein is furnished free of charge and based on technical data that Chemours believes to be reliable. It is intended for use by persons having technical skill, at their own risk. Because conditions of use are outside our control, we make no warranties, express or implied, and assume no liability in connection with any use of this information. Nothing herein is to be taken as license to operate under or a recommendation to infringe any patents.

For more information, visit www.titanium.chemours.com

© 2019 The Chemours Company FC, LLC. Ti-Pure™ and any associated logos are trademarks or copyrights of The Chemours Company FC, LLC. Chemours™ and the Chemours Logo are trademarks of The Chemours Company. C-10416-2 (2/19)