FOGGING RESISTANCE

Developments in the USA have led to the availability of terephthalate plasticisers, for example dioctyl terephthalate (DOTP). Whilst these materials are very similar to the corresponding o-phthalate esters they are generally less volatile and are best compared with d-phthalates with one or more carbon atom in the alkyl chain. As with the linear dialkyl phthalates the terephthalates show good fogging resistance. This is a phenomenon in which new cars on storage fields awaiting delivery develop misting on the windows due, apparently, to the volatility of additives in PVC compounds used with the car. 

Surface/Spot Treatments 8arriers Fogging Resistant Packaging... 

Rusting and blistering of high solids polyester coatings on metal substrates. Salt fog resistance (300 h)... 

Butylated hydroxytoluene (BHT), or 2,6 di-fer -butyl-/ -cresol, was used for many years as an excellent antioxidant in polyether polyols. Owing to its intrinsic volatility, BHT was eliminated as an antioxidant and a new type of polyether called BHT free polyethers has appeared. The low volatility antioxidants give good fogging resistance, such as in interior automotive applications [140]. 

ISO DIS 6452, Determination of fogging resistance of trim materials in the interior of automobiles, 1996. 

Potential adverse effects affect color, affect outdoor performance, affect toxicity of products, decrease chemical resistance, decrease flame resistance, decrease fog resistance, decrease stain resistance, increase coefficient of friction, increase gas permeability, increase porosity, increase price, increase smoke generation, increase snrface tack, lower scratch resistance, lower tensile strength modulus, lower wear resistance... 

In another invention, plasticizers are prepared from a mixture of acids (acrylic, maleic, and fumaric) and alcohols having 6 to 18 carbon atoms. Mono and diesters are obtained during manufacturing process. The composition of stock is controlled to obtain plasticizer which has good electrical insulation properties, water extraction resistance, and fogging resistance. ... 

This traditional plasticizer has been manufactured since 1930s under the trade name of Mesamoll. Only recently Mesamoll II having lower volatility and better fogging resistance was introduced. These are improved by replacement of substituent R with paraffin of a higher molecular weight. 

Anti-fogging - resisting the release of ingredients that can be deposited on nearby surfaces and cause fogging - is particularly demanded by the automotive industry for materials used inside a car. It especially affects PVC and... 

Whether due to the lack of an alternative test method or other reasons, the salt spray test has endured in spite of clear data that, in some cases, it is misapplied and misused, thereby providing erroneous information. As indicated in paragraph 3.2, Prediction of performance in natural environments has seldom been correlated with salt spray results when used as stand alone data. Significance and Use, a modification made to ASTM B 117 in 1985, paragraph X2.2 specifically states, It should be noted that there is usually not a direct relation between salt (fog) resistance and resistance to corrosion in other media because the chemistry of the reactions, including the formation of films and their protective value, frequently varies greatly with the precise conditions encountered. ... 

Glycolube AFA-1 can be used at lower loadings than conventional anti-fogging/anti-static systems. Levels of 1.5-2.5 phr are recommended for effective fog resistance in flexible PVC food wrap formulations. Loadings as low as 1.5 phr are sufficient to meet NFPA code 99 specifications for static dissipation. 

ASTM D2132, Test MethodforDust-and-Fog Tracking and Erosion Resistance of Electrical Insulating Materials, Vol. 10.02, ASTM, Philadelphia, Pa., 1989. 

Formulation of effective corrosion-resistant coatings is made difficult by the lack of a laboratory test that can provide rehable predictions of field performance. The most widely used test is exposure in a salt fog chamber. It has been shown repeatedly, however, that the results of such tests do not correlate with actual performance (125). Outdoor exposure of panels can provide useful data, especially in locations where salt spray occurs, but predictions of performance are not always satisfactory (126). 

Sa.lt Spray Tests. One of the older accelerated corrosion tests is the salt spray test (40). Several modifications of this imperfect test have been proposed, some of which are even specified for particular appHcations. The neutral salt spray test persists, however, especially for coatings that are anodic to the substrate and for coatings that are dissolved or attacked by neutral salt fog. For cathodic coatings, such as nickel on steel, the test becomes a porosity test, because nickel is not attacked by neutral salt fog. Production specifications that call for 1000 hours salt spray resistance are not practical for quahty acceptance tests. In these cases, the neutral salt spray does not qualify as an accelerated test, and faster results from different test methods should be sought. 

Soluble corrosion products may increase corrosion rates in two ways. Firstly, they may increase the conductivity of the electrolyte solution and thereby decrease internal resistance of the corrosion cells. Secondly, they may act hygroscopically to form solutions at humidities at and above that in equilibrium with the saturated solution (Table 2.7). The fogging of nickel in SO2-containing atmospheres, due to the formation of hygroscopic nickel sulphate, exemplifies this type of behaviour. However, whether the corrosion products are soluble or insoluble, protective or non-protective, the... 

D 2059 1987 Test method for resistance of zippers to salt spray (fog)... 

Chlorinated polyethylene CPEs provide a very wide range of properties from soft/ elastomeric to hard. They have inherent oxygen and ozone resistance, have improved resistance (compared to PEs) to chemical extraction, resist plasticizers, volatility, and weathering. Products do not fog at high temperatures as do PVCs and can be made flame retardant. 

The most common plasticisers for PVC are phthalate esters prepared from aliphatic C8 alcohols. For high temperature applications higher molecular weight esters are used, e.g., from mellitic acid, which are resistant to volatilisation and are used for PVC interiors in cars (to prevent fogging of windscreens). 

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