October. 1923
IiVD USTRIAL A N D ENGINEERING CHEMISTRY
1033
Some Factors Which Affect t h e Plasticity of a PaintL By Eugene C. Bingham and Alfred G. Jacques 4
LAFAYETTE COLLEGE, EASTON, PA.
E A R L I E R work by plastometer becomes conIt is practicable to express quantifatioely the effects produced tinually st;, 1.742, temperature Z s o C., capillary N o . 1 0 . Ground in ad atmosphere of carbon dzoxide 0.61 340 16 0.61 280 24 0.63 280 32 0.64 280 49 270 0.62 56 0.61 280 64 Paint N , 60 fier cent lithopone f n d 40 p,er cenl acid-refined linseed oil density X 1.747, temperature 25 C., capzllary N o . 1 0 . Ground in a ; atmosphere of nitrogen 0.51 310 6 230 0.58 22 210 0.59 34 200 0 . 6 0 40 0.57 150 48 95 0.57 52 100 0.55 56 0.56 150 70 80 0.53 110
CONCLUSIONS 1--As the grinding of a pigment in oil progresses, the yield value a t first decreases but after 30 hours becomes constant. The mobility under the same conditions a t first increases, passes through a maximum, and then decreases more and more rapidly. The maximum occurs after about 30 hours in these experiments. 2-On measuring .different concentrations of pigment suspended in oil, the yield value-weight concentration curve is found to be linear except a t low concentrations, thus confirming the findings of Bingham, Bruce, and Wolbach. All concentrations exhibit a yield value. The concentration of zero yield value is apparently independent of the nature of the medium. The mobility-weight concentration curve is also linear and theconcentration of zero mobility is apparently independent of the nature of the vehicle. The theory would lead one to expect that simpler relations would be found when using volume concentrations, but this is not the case, for which no explanation has yet been given. 3-Silica and Lithopone have very different plasticity a t the same weight concentration. When they are compared at equivalent volume percentages, however, the mobilities
Vol. 15, No. 10
are nearly the same and the yield values are not very different. This fact is the more striking since the particle size in the two pigments is so different. 4-Comparing blown oil with acid-refined linseed oil a t the same concentration of pigment, the effect of the fluidity of the medium is shown. The mobility falls off in presumably the same ratio as the fluidities of the oil, but the yield vaIue is independent of the fluidity of the oil. 5-Polar colloids-as, for example. aluminium stearatehave very slight influence on the mobility, but they have an extraordinary effect in raising the yield value. 6-It is difficult to grind a pigment into pure mineral oil having the same fluidity as linseed oil and it is still more difficult to make a satisfactory plasticity determination on the resulting suspension. However, 0.2 per cent of oleic acid deflocculates the suspension and lowers the yield value about 80 per cent, while the mobility remains unchanged. 7-Moisture exerts a prodigious effect on the plasticity of paint, 0.5 per cent of moisture raising the yield value from 90 to 3450, and a t the same time reducing the mobility to one-fourth of its former value. 8-Oxidation and polymerization affect the fluidity of an oil, so we should expect the mobility to be affected. It was t,hought that the fall in the mobility on Iong grinding might be attributable to one of these causes, but grinding in an atmosphere of nitrogen only prevented it, partially. A paint ground in an atmosphere of carbon dioxide has a yield value three times as high as when ground in the air. ACKNOWLEDGMENT The writers are indebted to the E. I. duPont de Nemours and Company for the generous assistance which has made this investigation possible. Oxygen and Oxygenated Air in Metallurgical Processes Revolutionary changes in the metallurgy of iron, by which production costs should be materially decreased and quantities of lowgrade ore and smelting fuels now considered worthless be made available as the result of the use of oxygen and oxygenated air in blast furnace practice, are suggested in a report recently made to the Department of the Interior by a committee appointed by the Bureau of Mines to study the problem. In the past it has been necessary in the production of 1 ton of pig iron to pass 3 tons of inert nitrogen through the blast furnace, resulting in serious heat and metal losses. The elimination of such losses by the substitution of oxygen, or a mixture of oxygen and air, has long been considered, but has not been put into practice on account of the inability t o produce oxygen in quantities at sufficiently low cost t o make such application industrially possible. I n view of the many recent developments in oxygen manufacture, and considering the increasing cost and decreasing quality of the nation’s raw materials, the Bureau of Mines appointed an advisory committee, of which M. H. Roberts of New York is chairman, to study the problem of the application of oxygen or oxygenated air to metallurgical and allied processes. This committee has made a thorough survey of the existing processes for the manufacture of 99 per cent oxygen, and finds that the oxygen industry is now able to make plants for supplying large quantities of oxygen t o metallurgical industries a t low cost. The data collected by this committee indicate that the production and utilization of cheap oxygen should also accomplish great economies in the metallurgy of zinc. It is believed that similar economies can be effected in the metallurgy of copper, and in fact in all branches of nonferrous metallurgy. The committee has developed plans for experimentally determining the effects of oxygen-enriched air upon the operation of the blast furnace, and it is recommended that these plans be put into effect as the first step of an extended research as to the general applicability of oxygen to metallurgy. The knowledge that German industrial concerns are working actively on the application of oxygenated air to metallurgical processes has greatly concerned American iron and steel interests, and the industry is making insistent demands for research work of this nature.
