Moisture resistant coatings

Uses Biodeg. thermoplastic for film (lawn and garden bags), extrusion coatings (moisture-resist, food pkg.), and fiber (agric. and horticultural seed mats, root covers, mulch films, erosion control fibers)... 

Marlipal 1618/11 Marlipal 1618/80 coating, moisture-resistant cable... 

Cellulose acetate butyrate. Cellulose coating, moisture-resistant elec, braid... 

Methyl laurate. Methyl linoleate Methyl coating, moisture-resistant harnesses... 

ParafUn PEG-4 PEGS PEG-8, PEG-9-, coating, moisture-resistant wire... 

The critical property for conformal coatings is resistance to chemicals, moisture, and abrasion. Other properties, such as the coefficient of thermal expansion, thermal conductivity, flexibiHty, and modulus of elasticity, are significant only in particular appHcations. The dielectric constant and loss tangent of the conformal coating are important for high speed appHcations. 

Laminates. Laminate manufacture involves the impregnation of a web with a Hquid phenoHc resin in a dip-coating operation. Solvent type, resin concentration, and viscosity determine the degree of fiber penetration. The treated web is dried in an oven and the resin cures, sometimes to the B-stage (semicured). Final resin content is between 30 and 70%. The dry sheet is cut and stacked, ready for lamination. In the curing step, multilayers of laminate are stacked or laid up in a press and cured at 150—175°C for several hours. The resins are generally low molecular weight resoles, which have been neutralized with the salt removed. Common carrier solvents for the varnish include acetone, alcohol, and toluene. Alkylated phenols such as cresols improve flexibiUty and moisture resistance in the fused products. 

The pelargonic acid by-product is already a useful item of commerce, making the overall process a commercial possibiUty. The 13-carbon polyamides appear to have many of the properties of nylon-11, nylon-12, or nylon-12,12 toughness, moisture resistance, dimensional stabiUty, increased resistance to hydrolysis, moderate melt point, and melt processibiUty. Thus, these nylons could be useful in similar markets, eg, automotive parts, coatings, fibers, or films. Properties for nylon-13,13 are = 56 (7 and = 183 (7 (179). 

Erucic acid, H00C(CH2) CH=CH(CH2)jCH, can be economically obtained from rapeseed ana crambe abyssinica oils and is potentially a major source of industrial materials. It can be ozonized to brassylic acid, HOOCCCH ), COOH, which is known to impart flexibility and moisture resistance to nylons. Here preliminary results of a study of brassylic acid as a monomer for polyester resin/melamine resin coatings are described. It is demonstrated that brassylic acid imparts good flexibility to such coatings. It is also shoim that brassylic acid is polymorphic. 

Poly(vinylidene chloride) (XLII) and its copolymers with vinyl chloride, acrylonitrile, and acrylates, usually produced by the suspension or emulsion process, are useful as oil, fat, oxygen, and moisture-resistant packaging films (Saran wrap), containers, coatings, tank liners, and monofilaments in drapery fabrics and industrial filter cloths. 

Chlorination of natural rubber (NR) is carried out with chlorine in carbon tetrachloride solution at 60-90°C to yield a chlorinated rubber containing about 65% chlorine, which corresponds to 3.5 chlorine atoms per repeat unit. The process is complex and includes chlorine addition to the double bond, substitution at allylic positions, and cyclization. Chlorinated rubber has high moisture resistance and is resistant to most aqueous reagents (including mineral acids and bases). It is used in chemical- and corrosion-resistant paints, printing inks, and textile coatings. Bromination of butyl rubber is also practiced [Parent et al., 2002]. 

Chen, G., Broad, R., Valentine, R.W., and Mannix, G.S. (2001) Ethylene-vinyl acetate copolymer as moisture resistant coating for metal fuels in pyrotechnic compositions, US Patent 6,174,391 Chem. Abstr., 134 (7), 88437s. 

Silanes. Silanes and silane derivatives dominate the small market for inorganic binders. These materials are used both m combination with organic binders and by themselves. As co-binders, they increase the chemical and moisture resistance of a film, When used by themselves, they form brittle, very chemical-resistant films. Silane coatings are usually more expensive than their organic counterparts and must be kepi dry before application,... 

Frequently, adhesion promoters are used. The substrates are primed or coated with a thin layer of an adhesion promoter, typically HMDS, prior to spin coating with resist (18). Possibly, the primary action of HMDS is to negate hydrophilic sites such as SiOH and trapped moisture on the substrate surface that would otherwise repel the photoresist. HMDS is applied by dipping, vapor priming in special chambers, or spin coating. Spin coating is most often accomplished with the same equipment that is used to coat resists. No high-temperature bake other than the resist prebake is required. 

Many seeds become dormant as a means of survival and are able to germinate after many years in the soil. Factors that influence seed germination and seed dormancy include temperature, moisture, oxygen, light, inhibitors (e.g., allelopathic effects), hardness or impermeability of seed coats, mechanically resistant seed coats, immature embryos, and after-ripening requirements (e.g., cool temperatures for several months). Weed seeds may survive and germinate due to several of these characteristics (Pareja et al, 1985). 

Paint compounds which do not provide these features to a satisfactory degree are either low-grade paints or merely coatings. A number of coatings have been offered on the market to provide protection against fire. Some of these are effective fire-retardant compounds, but the majority will not withstand weathering and thus have limited interior use only. To overcome this deficiency, manufacturers recommend a second or protective coat of moisture-resistant material. As an alternative means of achieving this same result, fire-retardant chemicals can be sprayed or brushed on wood and protected by a normal paint after the chemical dries. 

Figure 4 shows the insulative ability of the above formulation. Three coats were applied over a primer to a total dry film thickness of 20 mils, allowing 24 hours dry time between coats. This graph indicates complete failure in 8 minutes. When subjected to other tests the coating lacked adhesion to metal, moisture resistance, and flexibility. After, puffing, the coating disintegrated under vibration. 

Polysulfides and mercaptan Moisture resistance Quick set time Flexible Odor Poor elevated-temperature performance Poor tensile strength Adhesives and sealants Civil engineering Casting and encapsulation Coatings... 

Catalytic curing agents (e g., tertiary amines) Long pot life High heat resistance Can be used as an accelerator or as the sole curative Long elevated-temperature cure Poor moisture resistance Rigid Adhesives Electrical encapsulation Laminates Powder coatings... 

This oil is very stable and lasts for a long time without oxidizing. It was originally promoted as a substitute for spermaceti, the oil derived from whales. Most of its uses are cosmetic, in soap, shampoo, sun-tan lotions, and skin cream. Mixed with other compounds, it is useful in lubricants, candles, polish for wood and leather, and as moisture-resistant coatings. 

Phillips and Timms [599] described a less general method. They converted germanium and silicon in alloys into hydrides and further into chlorides by contact with gold trichloride. They performed GC on a column packed with 13% of silicone 702 on Celite with the use of a gas-density balance for detection. Juvet and Fischer [600] developed a special reactor coupled directly to the chromatographic column, in which they fluorinated metals in alloys, carbides, oxides, sulphides and salts. In these samples, they determined quantitatively uranium, sulphur, selenium, technetium, tungsten, molybdenum, rhenium, silicon, boron, osmium, vanadium, iridium and platinum as fluorides. They performed the analysis on a PTFE column packed with 15% of Kel-F oil No. 10 on Chromosorb T. Prior to analysis the column was conditioned with fluorine and chlorine trifluoride in order to remove moisture and reactive organic compounds. The thermal conductivity detector was equipped with nickel-coated filaments resistant to corrosion with metal fluorides. Fig. 5.34 illustrates the analysis of tungsten, rhenium and osmium fluorides by this method. 

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