HBPF

Whereas the vegetable oils listed have a viscosity some ten times that of the high boiling petroleum distillate, the methyl fatty acid derivatives are much closer, and in fact have absorption characteristics approaching those of the of the 280/310 (HBPF) solvent.

Table 1: Properties of solvents, ester, and oils Viscosity Surface tension dPa.s @ 20[degrees] C mN/[m.sup.-1] @ 20[degrees]C Soybean oil 0.64 33.0 Sunflower seed oil 0.60 33.0 Rapeseed oil 0.66 32.0 Linseed oil 0.47 35.0 Mineral oil, 0.21 33.0 (Singer machine oil) White spirit 0.01 23.0 Odorless kerosene 0.02 27.0 280/310 HBPF (a) 0.06 28.0 Methyl fatty acid 0.075 32.0 esters type A(b) Methyl fatty acid 0.08 32.0 ester of tall oil F.A (c) (a) 280/310 High boiling petroleum distillate--low aromatic content (Haltermann) (b) Methyl fatty acid ester: A mixture of unsaturated and saturated fatty acid esters.

Table 2: Effective pore radius Test [eta] @ 20 [gamma] h/[square r cos oil/solvent [degrees]C, mN[m.sup.-1] root of [theta] [mu] dPa.s @ 20[degrees] (t)] [10.sup.-4] cm C Capillary rise rate Odorless 0.02 27 0.26 1.0 kerosene 280/310 HBPF 0.064 28 0.153 1.1 Me ester A 0.075 32 0.153 1.1 Soybean oil 0.64 33 0.054 1.1 Evaluation of r cos[theta] from h = [square root of ([[r[gamma]cos[theta]t]/[2[eta]])] r cos [theta] = [(h/[square root of (t)]).sup.2] x [2[eta]/[gamma]]