Continuous processes, coloration

The reaction is completed after 6—8 h at 95°C volatiles, water, and some free phenol are removed by vacuum stripping up to 140—170°C. For resins requiring phenol in only trace amounts, such as epoxy hardeners, steam distillation or steam stripping may be used. Both water and free phenol affect the cure and final resin properties, which are monitored in routine quaHty control testing by gc. OxaHc acid (1—2 parts per 100 parts phenol) does not require neutralization because it decomposes to CO, CO2, and water furthermore, it produces milder reactions and low color. Sulfuric and sulfonic acids are strong catalysts and require neutralization with lime 0.1 parts of sulfuric acid per 100 parts of phenol are used. A continuous process for novolak resin production has been described (31,32). An alternative process for making novolaks without acid catalysis has also been reported (33), which uses a... 

Both batch and continuous processes employ excess sulfur and operate at 85—110°C. Trace amounts of polysulftdes produce a yellow color which iadicates that all the ammonium sulfite has been consumed. Ammonium bisulfite is added to convert the last polysulfide to thiosulfate and the excess ammonia to ammonium sulfite. Concentrations of at least 70% (NH 2S2 3 obtained without evaporation. Excess sulfur is removed by filtration and color is improved with activated carbon treatment or sodium siUcate (66). Upon cooling the aqueous concentrated solution, ammonium thiosulfate crystallines. 

Fig. 9.2 Synthesis flowchart of modern carbon for essentially flat C3 compounds. Some of the steps (2,3 8,9) may be connected into a continuous process. The energy intensity of the steps is indicated by the coloring scheme.

Batch Stirred Tank S03 Sulfonation Processes. If the color of the derived sulfonate is not critical, such as in the production of oil-soluble ag-emulsifiers, a simple batch sulfonation procedure can be employed based on vaporizing liquid S03 (Ninol Labs, 1952) (13,263). Pilot Chemical Company adapted the original Morrisroe 60—70% oleum—S02 solvent sulfonation process (256) to utilize 92% liquid SO,—8% liquid S02 mixtures, and more recendy using 100% liquid S03. This cold sulfonation low viscosity sulfonation process produces excellent quality products, and reportedly has also been adapted for continuous processing as well. The derived sulfonic acid must be stripped of S02 solvent after completing sulfonation and digestion. 

The discontinuous explosion process is the oldest technical process. It was mainly used for the production of color blacks. Continuous processes were later developed with production rates up to 500 kg/h [4.20], Acetylene or acetylene-containing gases are fed into a preheated, cylindrical reactor with a ceramic inner liner. Once ignited, the reaction is maintained by the decomposition heat that is evolved. The carbon black is collected in settling chambers and cyclones. Approximately 95-99% of the theoretical yield is obtained. 

Dyeing Processes. Since safe and efficient continuous dyeing methods are well known, and large yardages are often dyed in the same color, PES-CEL mixtures are frequently dyed in continuous processes [142], Nevertheless, batch dyeing is... 

Employee training is a continual process. Monthly safety meetings (25 hours annually) and specific training necessary to fulfill the requirements of the various special OSHA and EPA programs (approximately 24 hours annually) are mandatory. Employees required to operate or work in close proximity to production equipment at any color compounding facility should be required to, at a minimum, complete 40 hours of specialized on-the-job training under the direct supervision of a qualified operator (for the equipment of concern). 

The advantages of this type of continuous process over batch or continuous distillation in a still pot include low residence time (1-2 minutes) and a small difference between the vapor temperature and the liquid film temperature. The temperature of the glycerine can be tightly controlled, thereby reducing the formation of odor, color, and other impurities. This system does not require stripping... 

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