Polyvinyl butyrate, formation

Screen Preparations, 100 micron thick x-ray intensifying screens were prepared using standard doctor blade coating techniques. The final phosphor volume was 50% when the coatings were dried. In most instances, the phosphor suspensions were prepared using polyvinyl butyral binders with viscosities adjusted to 2000 centipoise for the doctor blade operation and care was taken to avoid convection cell formation (9). A cross section of the screen construction is shown in Figure I. The completed screens consist of polyester (Mylar) base about 10 mil. thick, a 50 micron thick (TI02 (rutile) reflector layer, a 100 micron thick phosphor layer, a 10 micron thick clear cellulose acetate butyrate top protective layer. 

Acrylate polymers and certain polyvinyl butyrals, sihcone fluids, tita-nate esters and fluorocarbon compounds are used as flow control agents in powder coatings to modify the surface tension of the film in the melt stage, preventing crate formation and improving substrate wetting. 

The acetals are terpolymers reflecting the three reactions which are used in their manufacture. The moieties are represented in Fig. 2. Manufacturers offer a variety of hydroxyl levels and molecular weight. The acetate level for conunercial polyvinyl butyrals is usually low offering little performance leverage for most applications. Higher acetate levels are common for the polyvinyl formats to improve solubility at the expense of strength and dimensional stability. ... 

Polyvinyl isobutyl ether C6H12O2 Amyl formate n-Butyl acetate s-Butyl acetate t-Butyl acetate Caproic acid Diacetone alcohol Diethylacetic acid Ethyl butyrate Ethyl isobutyrate... 

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