Lead-based paint stabilizing

Basic lead carbonate n. 2PbC03 Pb(0H)2. A very effective heat stabilizer, used where toxicity is of no concern as in electrical-insulating compounds. Its use is limited because of its tendency to form blisters during processing and to cause spew when exposed to weather, also by rising concern about lead in the environment. Gooch JW (1993) Lead based paint handbook. Plenum Press, New York. 

Lead-based paint that is blistering, flaking, peeling, or chalking can be repaired (technically referred to as being stabilized) to prevent the hazard from continuing. Once... 

For interim controls, lead-based paint was stabilized (sealed, intact, smooth, and cleanable) and friction and impact surfaces were treated properly. 

Source Hock, V. et al., Demonstration of lead-based paint removal and chemical stabilization using blastox, Technical Report 96/20, U.S. Army Construction Engineering Research Laboratory, Champaign, IL, 1996. 

Lead-Restricted Paint Normally, a paint having a lead content below a given limit, as used for applications where the presence of lead may be harmful. (Gooch JW (1993) Lead based paint handbook. Plenum, New York) Lead Salicylate (dibasic lead Salicylate) Pb (C6H40HC00)2-H20. a white crystalline material formerly used as a heat stabilizer. 

In suspension processes the fate of the continuous liquid phase and the associated control of the stabilisation and destabilisation of the system are the most important considerations. Many polymers occur in latex form, i.e. as polymer particles of diameter of the order of 1 p.m suspended in a liquid, usually aqueous, medium. Such latices are widely used to produce latex foams, elastic thread, dipped latex rubber goods, emulsion paints and paper additives. In the manufacture and use of such products it is important that premature destabilisation of the latex does not occur but that such destabilisation occurs in a controlled and appropriate manner at the relevant stage in processing. Such control of stability is based on the general precepts of colloid science. As with products from solvent processes diffusion distances for the liquid phase must be kept short furthermore, care has to be taken that the drying rates are not such that a skin of very low permeability is formed whilst there remains undesirable liquid in the mass of the polymer. For most applications it is desirable that destabilisation leads to a coherent film (or spongy mass in the case of foams) of polymers. To achieve this the of the latex compound should not be above ambient temperature so that at such temperatures intermolecular diffusion of the polymer molecules can occur. 

Lead powder can be combined with many binders [5.165], [5.166], It does not affect the stability or viscosity of the paint. Binders that absorb only small amounts of water are particularly suitable (e.g., epoxy resins, chlorinated rubber). When formulating paints based on lead powder, care must be taken not to dilute it with other pigments and extenders by more than 5 vol%. 

In the 5 years that followed (1965-70), three additional producers—American Potash, National Lead, and Pittsburgh Plate Glass—opened chloride-process plants. Sales of composite titanium calcium-base pigments continued to drop, as they had done over the previous 5 years in which Du Pont had ceased to produce them. This was due primarily to their adverse effect upon the stability of latex systems and the rapid replacement of alkyd and oleoresinous flat wall paints by flat latex paints. Two so-called "maximum-durability" pigments were introduced during this period—one by Du Pont and the other by National Lead. These pigments, although produced by different methods, both essentially eliminated the photochemical reactivity of the base titanium dioxide. 

For optimum results, the formulator has to adjust paint pH above 8 before adding this rheology modifier. If the pH is below 8 during the manufacturing process, the thickener can be destabilized and it can lead to grit formation. To ensure stability, it is recommended to add enough base to have a final pH of 8.5 to 9 (any types of bases can be used ammonia, sodium or potassium hydroxide and amine alcohol derivatives)... 

Sulfide staining n. (1) Discoloration of a plastic caused by the reaction of one of its constituents with a sulfide in a liquid, solid, or gas to which the plastic article has been exposed. Stabilizers based on salts of lead, cadmium, antimony, copper, or other metals sometimes react with external sulfides to form a staining metallic sulfide. (2) The formation of dark stains in a paint film, as a result of the reaction of atmospheric hydrogen sulfide with metallic compounds such as lead, mercury, or copper in the paint. 

Because of this tendency towards HCl elimination, stabilizers are necessary for PVC. There has been a large amount of research in this area. Lead stabilizers are effective but are no longer used to any extent in the U.S. When some imported toys are found to have lead contamination, if it is not from the paint or pigments, it can be from PVC made with lead stabilizers. For some time in the U.S., tin-based stabilizers have been widely used. Compounds such as dibutyltin bis (isooctylthioglycolate) are effective. 

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