Chemical resistance, plastics coated

The reaction mixture is filtered. The soHds containing K MnO are leached, filtered, and the filtrate composition adjusted for electrolysis. The soHds are gangue. The Cams Chemical Co. electrolyzes a solution containing 120—150 g/L KOH and 50—60 g/L K MnO. The cells are bipolar (68). The anode side is monel and the cathode mild steel. The cathode consists of small protmsions from the bipolar unit. The base of the cathode is coated with a corrosion-resistant plastic such that the ratio of active cathode area to anode area is about 1 to 140. Cells operate at 1.2—1.4 kA. Anode and cathode current densities are about 85—100 A/m and 13—15 kA/m, respectively. The small cathode areas and large anode areas are used to minimize the reduction of permanganate at the cathode (69). Potassium permanganate is continuously crystallized from cell Hquors. The caustic mother Hquors are evaporated and returned to the cell feed preparation system. 

There are several plastic coatings available commercially, some being more effective than others. However, the selected plastic coating must possess flexibility, resistance against impact, chemical attack, flow of galvanic currents and... 

Due to low hydrolytic and chemical resistance and to low melting point, aliphatic polyesters have long been considered to be limited to applications such as plasticizers or macromonomers for the preparation of polyurethane foams, coatings, or... 

The great drawback of organic materials for practical use, especially at elevated temperatures, is their inherent instability, thermal as well as mechanical. On the other hand great advances have been made in polymer technology. Composite plastics are used in the construction of supersonic airplanes to replace metals, because of their superior resistance to heat, and plastic coatings are frequently used to enhance the chemical resistance of surfaces. Therefore it is not improbable that properly synthesized organic materials may also find their practical application as catalysts or catalyst carriers. 

Many of the attributes of solvent-borne epoxy coatings could be carried over to the waterborne epoxy coatings. These same attributes are useful in the application of waterborne epoxies as adhesive systems. They include good adhesion to a variety of substrates such as metals, wood, concrete, glass, ceramics, and many plastics chemical resistance low shrinkage toughness and flexibility and abrasion resistance. 

Plastic coating materials have been exposed to all lands of performances and environments to meet the many different requirements that exist in the many different applications. Included are corrosion and chemical resistant, fire retardant or non-flammable, strippable, heat resistant, electrical insulation, and others reviewed above (Chapter 2). What follows is information that highlight some of the properties and tests that influence the performance of coatings. 

Preferred supplied forms are powders (gold bronze), pastes (aluminum) in plasticizers (like white oil, DINP etc.) and pellets in polyethylene. Due to the chemical nature of gold bronze, there are special coated pigments for use in high temperature processes (tarnish- or heat-resistant gold bronze). Also for use in PVC, special chemically resistant aluminum and gold bronze pigments are available. 

Vinyl dispersions are fluid suspensions of special fine particle size polyvinyl chloride resins in plasticizing liquids. When the system is heated to about 350F., fusion (mutual solubilization of resin and plasticizer) takes place. The dispersion turns into a homogeneous hot melt. When the melt is cooled below 140F., it becomes a tough vinyl coating with excellent physical properties such as flexibility, abrasion resistance, chemical resistance and excellent aging. 

Rubber or plastic-coated coverall (worn over underwear) with hood, chemical-resistant gloves, chemical-resistant boots, and goggles and half-face respirator (or full-face respirator). 

Chemical-resistant hood or Rubber- or plastic-coated safari-style hat. 

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