Process for coating crystalline explosives with polyethylene wax

#This invention relates to explosives and more particularly to polymeric wax coated explosives.

#Previous methods of coating crystalline high explosives use polyethylene wax emulsified with fatty acids and basic materials such as ammonia and morpholine. The explosive crystals are then slurried in the aqueous emulsion. The emulsion is then broken with a heavy metal salt such as BaCl.sub.2 thus freeing the polyethylene particles to coat the explosive crystals. After the particles are coated and the mixing operation is completed, the remaining water is removed and the coated crystals are washed. The effluent water from this process contains Ba.sup.++ ions which are highly toxic and quite costly to remove. The Ba.sup.++ ions must be removed before the effluent water can be disposed of in the conventional manner.

#According, an object of this invention is to provide a new method of coating high crystalline explosives with polymeric waxes.

#The emulsions used in the present process are composed of a polyethylene wax, potassium stearate as an emulsifier, KOH, and water. The waxes used are low molecular weight, emulsifiable polyethylene waxes which soften at temperatures of less than 100.degree. C. They are soft, pressable polyethylene waxes. Examples of suitable waxes are sold by Allied Chemical Company under the trademark AC-656.TM. and by Eastman Chemical Company under the trademark Empolene 110.TM..

#The ratio of water to polyethylene wax in the final emulsion may be from about 99:1 to 1:1. In other words, the weight percentage of polyethylene wax based on the weight of the wax plus water is from about 1.0 to 50.0. The higher percentages of wax make transportation and storage more convenient. A 1:1 ratio of water to wax (i.e., 50 weight percent wax) works well; however, it is possible that emulsions having much greater polyethylene wax contents would be difficult to dilute with water as requiring later in the process. Emulsions with low percentages of wax are used when a thinner coating of wax is desired. For most purposes a weight percent of from 10 to 30 is preferred, with 15 to 25 being more preferred. In other words, a weight ratio of water to polyethylene wax of from 9:1 to 2.33:1 is preferred, with from 5.67:1 to 3:1 being more preferred.

#The emulsifier used is preferably potassium stearate. Generally, stearic acid is added to the mixture and KOH is used to convert it to potassium stearate. The weight ratio of stearic acid to polyethylene wax is preferably in the range of from 1:5 to 1:6, though this may be varied some. Potassium hydroxide is used in an amount sufficient to convert the stearic acid to potassium stearate and to produce a pH of at least 9, preferably of from 9 to 12, in the final emulsion.