1070-4272/05/7802-0286 + 2005 Pleiades Publishing, Inc.
Russian Journal of Applied Chemistry, Vol. 78, No. 2, 2005, pp. 286!290. Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 2, 2005,
Original Russian Text Copyright + 2005 by A. Radbil’, Ismagilov, B. Radbil’.
AND INDUSTRIAL ORGANIC CHEMISTRY
Thermally Curable Emulsion Binders for Mold Cores
and Molds Based on Tall Pitch
A. B. Radbil’, R. M. Ismagilov, and B. A. Radbil’
Lesma Research Innovation, Limited Liability Company, Nizhni Novgorod, Russia
Ural Wood-Chemical Plant, Joint-Stock Company, Neivo-Rudyanka urban village, Sverdlovsk oblast, Russia
Received July 28, 2004
Abstract-Preparation of thermally curable emulsion binders for mold cores and molds using tall pitch
was studied. Preparation conditions, composition, and colloid-chemical properties of the resulting emulsions
Thermally curable binders (TCBs) for preparing
mold cores and molds should meet rather strict re-
quirements. The compression and tensile strength of
mold cores should be no less than 0.1230.20 (wet
state) and 12320 kgf cm
(after drying), respective-
ly. At the same time, the mixture should not adhere
to casting patterns when preparing mold cores (and
molds), especially with the so-called core-blowing
In [2, 3], we studied TCBs for sand and core stocks
with a tall pitch (TP) binder, which is a by-product
from production of cellulose by the sulfate procedure.
One of these TCBs (TOP brand) is a solution of TP
(50390 wt %) in an organic solvent (10350 wt %),
namely, in a hydrocarbon, alcohol, ketone, acetic acid
ester, or their mixture. However, aqueous solutions
of lignosulfonates (LSs) should be added to the sand
stock to provide the required strength and to improve
the geometry of mold cores and molds, which some-
what complicates the process.
In , we studied a TCB based on equal amounts
of a 60365% TP solution in kerosene and a 50%
aqueous solution of LS. However, this TCB fails
the provide a stable quality of the resulting molds and
cores because of the composition heterogeneity, main-
ly caused by the low aggregation stability of the emul-
sion based on the TCB component; it is unstable and
separates into aqueous and organic layers during stor-
age and use. Thus, development of stable emulsions
containing TP and LS is of particular importance for
both foundry and timber enterprises.
In this study, we analyzed formation of stable
emulsions based on TP and various LSs and examined
their colloid-chemical properties.
It is known that, depending on the composition
(TP and LS ratio) and preparation conditions, we can
obtain either oil-in-water (direct) or water-in-oil (re-
verse) emulsions. Due to the intense coloring and high
viscosity of the resulting mixtures, their type was
determined from the data on the electrical conduc-
tivity of the system and its components and from
the wetting angles of the glass (q
, deg) and waxed
, deg) supports. In the case of the water-in-oil
emulsions, the electrical capacitance reflecting the di-
electric properties of the system was also recorded.
Oil-in-water emulsions (Table 1, nos. 135) were
prepared using nonionic surfactants based on OP-10
polyoxyethylene alkylphenols and Reapon Pluronic
with the index of the hydrophilic-lipophilic balance
(HLB) equal to ~10. The electrical conductivity c
emulsion nos. 135 is 1.26 + 0.06 S m
, which is close
to the conductivity of the aqueous solution (c
0.15 S m
) and differs from that of the tall pitch by
more than three orders of magnitude (c
= 4.8 0
). These data show that emulsion nos. 135
belong to the oil-in-water type. This is also confirmed
by the linear dependence of the electrical conductivity
on the content of surfactant in the emulsion upon its
dilution with water (dispersion medium), which is il-
lustrated by the example for emulsion no. 4 (Fig. 1).
Fig. 1. Electrical conductivity ? of emulsion no. 4 vs.
Reapon surfactant concentration c (at dilution of the emul-
sion with water).