Russian Journal of Applied Chemistry, 2012, Vol. 85, No. 7, pp. 1118−1120.
Pleiades Publishing, Ltd., 2012.
Original Russian Text © A.V. Pokrovskii, M.A. Ishchenko, 2012, published in Zhurnal Prikladnoi Khimii, 2012, Vol. 85, No. 7, pp. 1151−1154.
AND POLYMERIC MATERIALS
Efﬁ cient Control of the Molecular Weight of Modiﬁ ed Epoxy
Resins in the Course of Their Synthesis
A. V. Pokrovskii and M. A. Ishchenko
St. Petersburg State Institute of Technology (Technical University), St. Petersburg, Russia
Received April 18, 2012
Abstract—Epoxy resin modiﬁ ed with sebacic acid was synthesized. It exhibits improved elastic properties and
Application of coatings of high-molecular-weight
epoxy resins is a widely used way to protect metal sheets
from the action of external factors [1–3]. In particular, E-
05k and E-04kr resins used for this purpose are produced
in Russia. Their characteristics are given in Table 1 .
Further progress of studies in this ﬁ eld involves syn-
thesis of epoxy resins, modiﬁ ed with aliphatic dibasic
acids, of molecular weight from 2500 to 4500, which is
close to the molecular weight of E-05 and E-04 resins. In
particular, the epoxy resin modiﬁ ed with a small amount
(about 9%) of sebacic acid acquires at least two advantag-
es over common epoxy resin of equal molecular weight.
First, the coating obtained from the modiﬁ ed resin, pre-
serving high strength, is considerably more elastic and
impact-resistant owing to the presence of ﬂ exible aliphatic
fragments acting as “internal plasticizers.” Second, the
viscosity of solutions of these resins is lower by an order
of magnitude than that of the unmodiﬁ ed resins, which
allows the dry residue of ﬁ nal paint-and-varnish coating
formulations to be increased.
The modiﬁ ed epoxy resins can be prepared by a
somewhat modiﬁ ed procedure  involving successive
addition to a low-molecular-weight epoxy resin, e.g.,
ED-20, of sebacic acid (SA) and the diphenylolpropane
(DPP) in the presence of a catalyst at 170–180°С.
Previously amines such as triethanolamine and piperi-
dine were used as catalysts; today quaternary ammonium
salts, in particular, triethylbenzylammonium chloride
(TEBAC), are used.
The goal of this study is synthesis of sebacic acid
modiﬁ ed epoxy resin and determination of the reaction
parameters that affect the molecular weight of the product
General procedure: 10 mol of ED-20 (с
= 22.2%) +
2.5 mol of SA + 6.5 mol of DPP; molar ratio ED-20 :
(SA + DPP) = 10 : 9.
A 300-ml reactor was charged with 77.38 g of Epikote
epoxy resin, 10.07 g of sebacic acid, 0.12 g of TEBAC
(catalyst), and х g (х = 0–7.5) of butyl Cellosolve (BC).
The mixture was heated with stirring to 115–120°С. At
this temperature, a slight exothermic effect was observed
owing to the reaction of carboxy groups of sebacic acid
with epoxy groups. The mixture was kept for 30 min at
120°С, after which 29.55 g of diphenylolpropane was
Table 1. Characteristics of E-05k and E-04kr resins
Parameter E-05k E-04kr
Epoxy equivalent weight 1500–2400 2150–4300
Epoxy group content, % 1.8–2.8 1.0–2.0
Viscosity, Pa s
(s for VZ-4),
40% solution in Cellosolve
Hydroxy group content, % 6.5 6.8