Ballast groups

A review of synthetic methods for the most popular photoactive compounds used in diazoquinone resists—DNQ-5-sulfonate and DNQ-4-sulfonate—has been provided by Ershov et al. The synthesis typically begins with naphthalene derivatives, and proceeds via introduction of a sulfonic acid group, followed by diazotization and reaction with thionyl chloride to yield the sulfonic acid chloride (Scheme 7.2). In the next step, the chloride is reacted in a base-catalyzed esterification with a suitable ballast group or backbone, which usually is a multifunctional phenol, less frequently a monofunctional phenol or an aliphatic alcohol. ... 

As mentioned in section 2.3, the DNQ group can be attached to the polymer backbone (polymer 4 in Table 2.2) by reaction of the DNQ-sulphonyl chloride with an amine group on the polymer. Alternatively, the DNQ-sulphonyl chloride can be reacted first with a ballast group before mixing with the polymer. The most common class of ballast groups comprises hydroxybenzophenone analogues, an example of which is shown in Fig. 2.18. 

Subtractive dye precursors (couplers) that could be immobilized in each of the silver containing layers were sought, so that dye formation in all layers could proceed simultaneously rather than successively. The first of these to be commercialized were in Agfacolor Neue and Ansco Color films, introduced soon after Kodachrome film. These reversal working films contained colorless couplers that were immobilized (ballasted) by the attachment of long paraffinic chains. The addition of sulfonic or carboxyUc acid groups provided the necessary hydrophilicity to make them dispersible as micelles in aqueous gelatin. 

The first step in good pretreatment practice is the segregation of major wastewater streams. This frequently simplifies waste treating problems as well as reducing treatment facility costs. Treatment at the source is also helpful in recovering byproducts that otherwise would not be economically recovered from combined wastes downstream [35]. Four major pretreatment processes that are applicable to individual process effluents or groups of effluents within a refinery are sour water stripping, spent caustics treatment, ballast water separation, and slop oil recovery. These are discussed below. 

Scheme II. Sequential photolysis of DNQ groups attached to a central ballast molecule during polyphotolysis. Maximum resolution enhancement occurs when the totally photolyzed material controls the dissolution rate.

Butterworth, G. J., et al., Studies of Tank Washing on British Purpose during Ballast Voyage from Isle of Grain to Cape of Good Hope April 7th to May 5th 1977, Electrostatics and Physics Group, UKAEA Culham Laboratory, Report No. CLM/RR/D2/34, February 1978. 

By 1967 an electrician, Harold Wilbur, was assigned to our group, He modified these small contact printers, so that they could expose an 8 by 10-inch negative onto a piece of our photosensitive paper. He inserted a number of blacklite blue fluorescent lamps and suitable ballasting, so that a print could be obtained in ca. 20 seconds. We could thus make contact prints of continuous tone and lithographic negative in very little time. Wilbur made dozens of these, and they were used by our group, and later by sales personnel to demonstrate the... 

The ballast tanks as shown in Fig. 11.4 are internally mounted air tanks arranged in two groups, 9 central and 18 peripheral. Each ballast tank is 16 ft high and 3 ft in diameter. The bottom tapers to a cone and terminates in a nozzle 2 ft above the floor of the tank. Air is supplied to each tank intermittently at a controlled pressure for a specific time, resulting in a flushing action. When the air supply is off, the air in the ballast tank vents through a -in hole near the top of the waste tank in the air-supply line and allows the solution to flow back into the ballast tank. For a full waste tarik, air at 15 psig is supplied to a central ballast tank for about 60 s. 

For resists designed for applications in the near-UV region, good absorption at 365 nm (i-line) and at 405 nm and 436 nra (g-line) is required, and aromatic substituents present the best option. The most commonly used ballast compound is polyhydroxybenzophenone, where one to three (or even four) hydroxyl groups can be esterified with diazoquinone sulfonyl-chloride, as discussed above. A popularly used dissolution inhibitor is a substituted 2,3,4-trihydroxy benzophenone of stmcture (in), " where DQ stands here for diazonaphthoquinone. One other popular diazoquinone derivative found in commercial resists is the sulfonyl ester of cumylphenol. Similar materials such as shown in structure (IV) have also been employed in resist applications. ... 

The effect of the structure of the inhibitor on the dissolution rate of the resist and on its lithographic performance has also been reported by Trefonas and Daniels. These investigators studied the effects of the number of diazoquinone units attached to a polyfunctional inhibitor (III). For example, with benzophenone as the central component (ballast), they prepared six derivatives by gradually substituting all six hydroxyl groups of hexahydroxybenzophenone by diazoquinone moieties, which yielded six different photoactive species. The ratio q of active groups to ballast thus had values between 1 and 6. They used trisubstituted... 

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