Levelling in coatings

Waterborne epoxy dispersions have been employed effectively for many years in the coatings market, primarily for the surface protection of concrete and metals. These products were developed in response to environmental regulations to reduce solvent levels in coatings. Since these... 

A1 Typical potential hydrogen levels (moisture levels in coatings and fluxes). (Heights of curves indicate relative frequency of test results for each type of consumable.)... 

CAS 471-34-1 EINECS/ELINCS 207-439-9 Uses Pigment for plastics (PVC, PU, polyester, polyolefins), emulsion paints, primers, powd. coatings, adhesives, paper/board Features High brightness enables reduction of TiOj levels In coatings Properties Very wh. rhombohedral crystals 49% < 2 p sp.gr. 2.7 bulk dens. 0.9 g/ml (packed) oil absorp. 20/100 g dry brightness 95% pH 9 ref. Index 1.59 hardness (Mohs) 3 < 0.2% moisture Zetafil 5 [Microfill K. Zafranas]... 

Reduction of solvent level in coatings is important from both an ecological and an economic point of view. However, lowering the amount of solvent raises the viscosity, which has to be compensated for by lowering the molecular weight and/or the glass transition temperature of the binder. The general conditions and applications of LCP binders have been discussed by Pappas. 

Calcium carbonate, available both from natural sources and as precipitated forms (see Calcium compounds), is most useful in coating because of purity and high brightness, ie, 90—95%. Ground carbonates from marble deposits have high purity levels as do the carbonates from some chalk deposits. 

Increase adhesion tension. Maximize surface tension. Minimize contact angle. Alter surfactant concentration or type to maximize adhesion tension and minimize Marangoni effects. Precoat powder with wettahle monolayers, e.g., coatings or steam. Control impurity levels in particle formation. Alter crystal hahit in particle formation. Minimize surface roughness in milhng. 

Static sampling systems are defined as those that do not have an active air-moving component, such as the pump, to pull a sample to the collection medium. This type of sampling system has been used for over 100 years. Examples include the lead peroxide candle used to detect the presence of SO2 in the atmosphere and the dust-fall bucket and trays or slides coated with a viscous material used to detect particulate matter. This type of system suffers from inability to quantify the amount of pollutant present over a short period of time, i.e., less than 1 week. The potentially desirable characteristics of a static sampling system have led to further developments in this type of technology to provide quantitative information on pollutant concentrations over a fked period of time. Static sampling systems have been developed for use in the occupational environment and are also used to measure the exposure levels in the general community, e.g., radon gas in residences. 

Many structures are coated. Thus the presented area far exceeds the area of steel to be protected, which is restricted to uncoated areas and holidays in the coating. It is therefore practice to assume an arbitrary level of coating breakdown for coated areas to obtain the area of metal requiring cathodic protection ... 

There is suggestive evidence indicating that the changes in NCV associated with lead exposure may be transient. Muijser et al. (1987) investigated the effects of a 5-month exposure to lead during the demolition of a steel structure coated with lead-based paints. The motor and sensory nerve conduction velocities were measured in the median and ulnar nerves of eight exposed workers and compared with unexposed referents as well as themselves at 3 and 15 months after the termination of exposure. The mean PbB levels in the exposed workers were 82.5 18.9 pg/dL at the termination of exposure,... 

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