Baking process apparatus

On the other hand, economically advantageous routes by continuous baking process have also been described in recent years. The processes are carried out in self-cleaning mixing apparatus such as double screw extruders. More recent patent literature claims yields as high as 80%. 

As apparatus for the batch process, an enamel or steel reactor with an agitator and pressure steam or oil heating suffices. Apparatuses used in the continuous synthesis in the presence of solvents and in the bake process are described in [50] and [51,52], respectively. The choice of process depends on the availability and cost of the starting materials phthalodinitrile or phthalic anhydride. Although the phthalodinitrile process has certain advantages over the phthalic anhydride process, the latter is preferred worldwide because of the ready accessibility of phthalic anhydride. In this process the molar ratio of phthalic anhydride, urea, and cop-per(i) chloride is 4 16 1, with ammonium molybdate as catalyst. The mixture is heated in a high-boiling solvent such as trichlorobenzene, nitrobenzene, or kerosene. The solvent is removed after the formation of copper phthalocyanine. Fre-... 

The fusion is best carried out in vacuum, suitably in the vacuum baking apparatus used in the sulfonation of amines by the baking process. When the water is evaporated from the melt, the mass foams and, in order to avoid clogging the suction tube, this tube should be sufficiently wide and the tray should not be more than half filled. In order to obtain good yields, it is necessary to use about twice the sodium hydroxide required theoretically, i.e., about 8 moles per mole of sodium benzenedisulfonate. 

J. D. Bernal (London) In my opinion many, if not all, so-called oxide covered surfaces are, at ordinary and even under high temperature conditions, effectively hydroxyl-covered. I would like to recall in connection an observation many years ago by Farkas. He was filling an evacuated and baked out silica apparatus with pure Da gas and noted after pumping out that the gas was contaminated with Ha. On repeating the same process with pure R2 he found a smaller Da contamination. The simplest explanation was that the surface of silica is normally covered by OH groups from which the hydrogen is not driven even at red heat, but which can exchange easily with Da to form OD and HD. Other x-ray evidence on finely divided quartz shows that the hydroxide layer may be thicker than monomolecular. 

The whole apparatus is baked as efficiently as possible without evaporating large quantities of the manometric fluid or test substance, and is finally sealed off. The apparatus is returned to the vertical position and wholly immersed in a thermostatic bath. The level of the manometer liquid should be exactly equai under these conditions. The apparatus is then arranged as shown in the sketch with bulb B in solid carbon dioxide or liquid nitrogen. When equilibrium is attained the difference of level in the manometer limbs is observed with a cathetometer. The thermostat temperature is readjusted and the process repeated. ... 

Such reactors are doubtlessly superior to stationary apparatuses. First and foremost, the reactors with agitators offer an improved mixing of gaseous chlorine derivative with contact mass, which increases its conversion degree. They also help to considerably reduce the baking of contact mass, which increases the degree of silicon use. Such reactors can be also used for a continuous process of organochlorosilane production. 

The Step 2 product was spin-coated onto a silicone wafer and baked for 2 minutes at 215°C. Thereafter the anti-reflective mixture was coated with a Keum Ho petroleum photosensitive agent and baked for 90 seconds 110°C. After these processes the material was exposed to a light source by means of ASML/900 scanner apparatus and baked an additional 90 minutes at 130°C. The exposed wafer was developed using an aqueous solution of 2.38% tetramethyl-ammonium hydroxide. 

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