Chalking resistance

The true explanation for the poor chalk resistance of titanium dioxide had actually been reported by Renz (30) back in 1921 before commercial titanium pigments were even available, but this of course had not attracted the attention of the paint makers since his report... 

During the next 5 years (1935-40), a number of anatase titanium dioxide pigments appeared in which inorganic surface treatments— including, but not limited to, the hydrates of alumina, silica, and antimony—had been used to partially pacify this photochemical reactivity, improving color retention as well as chalk resistance. 

One year before the end of this period (in 1939), the first chalk-resistant pure titanium dioxide pigment was produced by the National Lead Co. Although never described as such at the time, this was also the first commercial rutile titanium dioxide, which accounted for some of its improved chalk resistance. Since the rutile structure had been attained by overcalcination, its overly large particle size and poor dispersibility prevented it from attaining the increased hiding power that should have accompanied its conversion to rutile, and the pigment was manufactured only until the end of World War II to satisfy the demand of the U.S. Navy for a durable titanium dioxide. 

Toluene diisocyanate and isophorone diisocyanate are mainly used to modify alkyd resins. Isophorone diisocyanate yields products with a lower yellowing tendency, higher pigment absorption, and considerably improved chalking resistance... 

On account of their insensitivity to solar radiation, some polyester resins are particularly suitable for weather-resistant topcoats (e.g.. facade claddings, blades of shutters and Venetian blinds, vehicle claddings, metal signs). Melamine-formulated paints are economical and have a well-balanced property profile. Polyurethane-formulated paints have an even better processability and weather resistance (colorfastness, chalking resistance) [2.92],... 

Exterior-use paints have a pigment volume concentration of 30-55%. They may be formulated with all of the aforementioned dispersions. Properties are adapted as appropriate to the substrates, climatic conditions, market circumstances, etc. The most important properties of exterior-use paints are their water and water vapor permeability (moisture balance), chalking resistance, and adhesion to the substrate. Special requirements apply in certain areas of application (e.g., COj protection on reinforced concrete, fungal and algal resistance in moist surroundings, crack bridging on cracked substrates, and alkali resistance on new mineral substrates). 

Features Produces coatings with good lightlastness and chalking resist. Properties Hazen < 50 color thinnable with ketones, esters, ether esters, toluene, xylene, naphtha dens. = 0.98 g/ml (20 C) vise. 1000 0 300 mPa -(23 C) acid no. 4 02 flash pt. = 40 C 55 01% NV < 0.1% water... 

Features Used in combination with isocyanates yields coatings with superior flow and flexibility cured coatings feature exc. weatherability. flex-ibilily. impact resist., gloss retention, chalking resist., and good corrosion protection... 

Features Durable max. chalk resist, and color retention, good UV resist. no VOCs, HAPs, ozone-depleting substances chemically stable and inert... 

Features Exc. durability, gloss retention, chalk resist. 

Features Exc. durability, gloss retention, chalk resist. good yellowing resist, in plastics disp. easily Properties 0.25 pm particle size oil absorp. 20 g/100 g Tipaque CR-97 [Ishihara USA]... 

Uses Pigment for automotive coatings, industrial paints, exterior paints Features Exc. durability gloss retention, chalk resist. 

Features (plastics) good weathering resist. good dispersibility in plasticizers and flexible vinyls (coatings) outstanding chalk resist., gloss retention, tint retention exc. exterior durability, hiding power, color acceptance... 

PVC plastisol based coating compositions are desirable coating vehicles from the standpoint of fabrication, thick film capability, and have the ability to be formulated with high solids, but generally exhibit poor durability, color retention, chalk resistance and dirt resistance ... 

Chalking resistance n. The ability of a coating to resist the formation of a friable... 

The classes of fillers used in formulating polysulfide oligomers are calcium carbonate (wet or dry ground limestone, chalks, or precipitated carbonates), carbon blacks (furnace and thermal), clays (calcined), silica and silicate fillers, and titanium dioxide (rutile is chalk resistant and preferred over anatase). In general, sealants are prepared using a combination of fillers to attain desired properties. 

This is another low refractive index (2.09) white pigment. It has good chalk resistance characteristics but its main functional application is in fire-retardant paints. 

Keywords Service life prediction Chalk resistance Gloss retention Color retention PVDF Poly(vinylidene fluoride) Weathering Durability Accelerated weathering UV fluorescent cabinet Coatings Waterborne PVDF-acrylic hybrid Color fade Outdoor weathering... 

This paper outlines how this quantitative weathering model can be used, first to better understand the linkages between natural and accelerated testing and, second, to predict outdoor gloss and color retention, as well as chalk resistance, for waterborne coatings based on new PVDF-acrylic hybrid latex materials. A general methodology for this approach is depicted in Fig. 5.1. 

Physical and Chemical Models for Chalk Resistance and Gloss and Color Retention... 

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