Laminates Chemical resistance

Polyolefin-carbon fiber composites Floor-layer laminates Olefin polymer laminates Chemical resistant laminates... 

Resists. Resists are temporary, thin coatings appHed to the surface of the copper-clad laminate. After patterning, these films act as masks that are chemically resistant to the cleaning, plating, and etching solutions used to define the circuit traces of the PWB. Both nonphotosensitive and photosensitive types are used. 

The thermal stabiUty of epoxy phenol—novolak resins is useful in adhesives, stmctural and electrical laminates, coatings, castings, and encapsulations for elevated temperature service (Table 3). Filament-wound pipe and storage tanks, liners for pumps and other chemical process equipment, and corrosion-resistant coatings are typical appHcations using the chemically resistant properties of epoxy novolak resins. 

Chemical resistance of thermosetting-resin-glass-reinforced laminates may be affected by any exposed glass in the laminate. 

Meta-phenylenediamine, a crystalline solid with a melting point of about 60°C, gives cured resins with a heat distortion temperature of 150°C and very good chemical resistance. It has a pot life of six hours for a 200 g batch at room temperature whilst complete cures require cure times of four to six hours at 150°C. About 14 pts phr are used with the liquid epoxies. The main disadvantages are the need to heat the components in order to mix them, the irritating nature of the amine and persistent yellow staining that can occur on skin and clothing. The hardener finds use in the manufacture of chemical-resistant laminates. 

Their main applications have been in heat-resistant structural laminates, electrical laminates resistant to solder baths, chemical-resistant filament-wound pipe and high-temperature adhesives. 

Elevated temperatures are necessary for cure and the chemical resistance of the laminates is inferior to those from unmodified resins. Because of problems in handling, the polyamides have found only limited use with epoxy resins, mainly for coating and adhesive applications. 

The furan or furane resins mainly find use because of their excellent chemical and heat resistance. In the past they have mainly been used in applications peripheral to the plastics industry such as foundry resins, for chemically resistant cements and for binders. Recent developments have facilitated their use in laminates for chemical plant. 

Laminates have been prepared for the manufacture of chemical plant. They have better heat and chemical resistance than the polyester- epoxide- phenolic- or aminoplastic-based laminates but because of the low viscosity of the resins were not easy to handle. Because they were also somewhat brittle, furan-based laminates have been limited in their applications. 

Aminos. There are two basic types of amino plastics - urea formaldehyde and melamine formaldehyde. They are hard, rigid materials with good abrasion resistance and their mechanical characteristics are sufficiently good for continuous use at moderate temperatures (up to 100°C). Urea formaldehyde is relatively inexpensive but moisture absorption can result in poor dimensional stability. It is generally used for bottle caps, electrical switches, plugs, utensil handles and trays. Melamine formaldehyde has lower water absorption and improved temperature and chemical resistance. It is typically used for tableware, laminated worktops and electrical fittings. 

Phenol-formaldehyde (phenolic) plastics The chemical resistance is affected by the phenol used, cresols giving the best acid resistance whilst xylenols are often used to obtain the best alkali resistance. For chemical-resistant applications the fillers used in moulding powder and reinforcing material in laminates should be inorganic, e.g. asbestos or glass. The resins are usually dark in colour. 

Phenolic phenol formaldehydes (PFs) are the low-cost workhorse of the electrical industry (particularly in the past) low creep, excellent dimensional stability, good chemical resistance, good weatherability. Molded black or brown opaque handles for cookware are familiar applications. Also used as a caramel colored impregnating plastics for wood or cloth laminates, and (with reinforcement) for brake linings and many under-the-hood automotive electricals. There are different grades of phenolics that range from very low cost (with low performances) to high cost (with superior performances). The first of the thermosets to be injection-molded (1909). 

Some wood furniture is now faced with plastic laminate. Its resistance to chemicals is superior to that of most regular finishes, and color choices are wide. Best of all, such surfaces are very easy to keep clean. In case of damage, however, repairs can be difficult. 

In European laboratories, ceramic tile is very popular, but it is rarely seen here. The cost is well below that of monolithic slabs but considerably higher than that of plastic laminate. Its resistance to both chemicals and heat is outstanding. In case of damage, single tiles may be replaced. Modem materials used for grouting are also very resistant to chemicals. The slightly uneven surface does not seem to cause any complaints among users. 

Dicyandiamide Latent cure Good elevated-temperature properties Good chemical resistance Good combination of tensile and peel strength Long elevated-temperature cure Insoluble in resin One-component adhesives Powder coatings Film and solid adhesives Laminates and other composites... 

Vinyls Excellent wealherability, superior electrical properties, excellent moisture and chemical resistance, self-extinguishing injection molding Continuous laminating Rotational molding... 

In the industry, for almost a century these laminates are used for their electrical properties, impact strength, wearing qualities, chemical resistance, decorative panels, or other characteristics depending on fiber-resin used with or without a surfacing material. They are used for... 

Bisphenol A. One mole of acetone condenses with two moles of phenol to form bisphenol A [80-05-07], which is used mainly in the production of polycarbonate and epoxy resins. Polycarbonates (qv) are high strength plastics used widely in automotive applications and appliances, multilayer containers, and housing applications. Epoxy resins (qv) are used in fiber-reinforced laminates, for encapsulating electronic components, and in advanced composites for aircraft—aerospace and automotive applications. Bisphenol A is also used for the production of corrosion- and chemical-resistant polyester resins, polysulfone resins, polyetherimide resins, and polyarylate resins. 

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