1070-4272/05/7805-0834+2005 Pleiades Publishing, Inc.
Russian Journal of Applied Chemistry, Vol. 78, No. 5, 2005, pp. 834 !838. Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 5,
2005, pp. 851!855.
Original Russian Text Copyright + 2005 by Syroezhko, Pankova, Korchemkin, Otchayannyi, Proskuryakov.
AND POLYMERIC MATERIALS
Softeners for Rubber Based on Shale Thermal
A. M. Syroezhko, Ya. I. Pankova, S. N. Korchemkin,
N. N. Otchayannyi, and V. A. Proskuryakov
St. Petersburg State Technological Institute, St. Petersburg, Russia
Received January 19, 2005
Abstract-The source of raw materials for manufacturing softeners for rubber is extended through applying
a nonwaste process of thermal dissolution of ordinary or enriched shale in crude producer-gas tar. The result-
ing products are less expensive than the conventional high-melting oil asphalts and oils.
Progress in the rubber industry is determined to
a considerable extent by extension of the source of
raw materials, i.e., by broadening of the spectrum of
the products used. In production of elastomers, the
weak point is a limited spectrum of softeners. Among
the commonly used products of this type are asphaltic
tar softeners, specialty bitumens, etc. Their introduc-
tion into rubber stocks allows control of the most
important performance characteristics of rubber stocks
and finished articles such as rubber-to-cord adhesion,
ozone resistance, and abradability. These products
serve also as dispersants for rubber stock components
and as reinforcing agents.
Virtually the only source of softeners of this type is
deep processing of oil. The rubber and tire industries
are large-scale consumers of high-molecular-weight
petroleum products such as PN-5 oil, black oils, tars,
Rubraxes, and other asphaltic tar products. These
softeners (plasticizers) demonstrate wide action spec-
trum: they reduce the shrinkage in calendering and
extrusion molding of rubber stocks, improve the
strength and heat resistance of rubber, and impart
moisture resistance and solidity to finished articles
[1, 2]. It was suggested that such products could be
obtained from sapropelic coals, among them shales,
whose reserves are huge.
In this study we examined the possibility of pre-
paration of shale-oil bitumens by thermal dissolution
of ordinary or enriched shales in shale-oil producer-
gas tar and also of their use as softeners for rubber.
Since bituminous softeners are used to improve per-
formance characteristics of heavily extended elas-
tomers and rubber stocks with a polymer body from
rubber reclaim and SKD butadiene rubber, an asso-
ciated task was to improve performance of the com-
posites by introducing the indicated softeners, thus
extending their application range.
Low branching of the macrochains and only slight
temperature dependence of the viscosity of SKD cause
its high cold flow in storage and transportation .
The processibility of SKD is characterized by its mil-
lability, estimated from the critical roll opening (mm).
The millability of SKD ranges from 0.5 to 2 mm,
depending on the molecular-weight distribution and
Crude producer-gas tar and ordinary Baltic shale or
enriched shale (Kerogen-70) (all the products from the
Slantsy Works, Joint-Stock Company) were charged
in 1 : 1 or 2 : 1 weight ratio into a three-necked flask
equipped with a stirrer, electric heater, and outlet sys-
tem for removal of liquid thermal dissolution prod-
ucts. The mixture was heated with continuous stirring
for a fixed time (Table 1).
The effect of shale-oil bitumens A, B, and C (plas-
ticizers) on properties of rubber stocks was studied
in comparison with commercial plasticizers [bitumen
BN-IV and bitumen G (Ukhta refinery)]. The charac-
teristics of the plasticizers studied are summarized
in Table 2.
The viscosity and tendency to scorching of the rub-
ber stocks were determined with a Mooney viscometer
according to GOST (State Standard) 10 722376. The
tensile strength f
, relative elongation (e
), and elonga-
tion set (q) were determined on a tensile-testing
machine (GOST 270375).