Studies on pitch trouble, its cause and its measures to be taken for its prevention (III)

Noncrystalizable resin of pitch

Abstract

1) Noncrystalizable resin : its separation and quantitative determination.
A substance was separated in crystals three times in succession from the sodium-carbonate-soluble content of the ether extract of pitch and noncrystalizable resin was left unextracted. Quantitative determination by paper chromatography disclosed that the resin was unsaturated fatty acid and the crystal resin acid. The two substances were next analized quantitatively by TwitchelPs method based on the difference in the rate of esterification between fatty acid and resin acid, as follows :
2) Fatty acid content of pitch.
The methyl esterized form of the fatty acid separated from the sodium-carbonate-soluble component of pitch was fractionated on distillation at reduced pressure into 50% liquid ester of fatty acid and 50 % undistillated residue. The free fatty acid obtained from this ester on saponification with 1 N alcoholic KOH ga to the spot denoting Rf for a mixture of oleic acid and linolic acid on separation by paper chromatography. The result was reexamined by disolving the free fatty acid in a solution of caustic soda and oxydizing the mixed solution with potassium permanganate. The dihydroxystearic acid and tetrahydroxysteatic acid showed plainly that the unsaturated fatty acid was mainly composed of oleic acid and linolic acid.
As saturated fatty acid was suspected to be contained in the fatty acid of the sodium-carbonate-soluble component, separative test was made by Twitchell's method. By method of paper chromatography and fractional distillation under reduced pressure of separated saturated fatty acid, the result was confirmed that palmitic acid and stearic acid were contained in the saturated fatty acid from the sodium-cabonatesoluble componet.
Paper mill Process Saturated fatty acid Unsaturated fatty acid It was reported in our previous paper that the ether soluble content of pitch is separable into sodiumbicarbonate-solubles, sodium-cerbonate-solubles, caustic-soda-solubles and neutral substances. The table below shows how the sodium-carbonate-soluble and caustic-soda-soluble substances are separable into resin and fatty acid
Unsaturated fatty acid % = 100% (saturated fatty acid %)
As will be seen from the forgoing result, pitch collected during each process, except that pitch stuck to the machine stone roll for the reason of its abundant fibers, are composed of ether insoluble components (ca. 1020%), which contain organic substances (ca. 80%) mainly fiber and inorganic substancgs %) and ether soluble components (ca.8090%), which contain strong acidic substance (ca.12%), unsaturated fatty acid (ca. 1023%, linolic acid and oleic acid), saturated fatty acid palmitic acid and stearic acid), pitch abietic acid (ca. 5070%) and unsaponifiable substance (ca. 928%) resen in all probability. Resin acid, existing in 2 or 3 times as much a quantity as fatty acid, is so high in viscosity as to make the resin practically inseparable, as stated in the previous report on the separation of crystalline resin.