Russian Journal of Applied Chemistry, 2012, Vol. 85, No. 10, pp. 1636−1639.
Pleiades Publishing, Ltd., 2012.
Original Russian Text © E.N. Shved, M.A. Sinel’nikova, Yu.N. Bespal’ko, N.M., Oleinik, 2012, published in Zhurnal Prikladnoi Khimii, 2012, Vol. 85,
No. 10, pp. 1709−1712.
AND POLYMERIC MATERIALS
Amines–Boron Triﬂ uoride Complexes as Catalyst
for Cold Curing Epoxy Resin ED-20
using Anhydride Curing Agents
E. N. Shved, M. A. Sinel’nikova, Yu. N. Bespal’ko, and N. M. Oleinik
Donetsk National University, Ukraine
Received June 8, 2012
Abstract—The reaction of the anhydride curing epoxy resin ED-20 in the presence of boron triﬂ uoride–amines was
investigated in the temperature range 303–393 K. An effect of the basicity of the amine in the complex on the speed
of the process was assessed. Based on correlations of a structure of the catalyst–temperature epoxy compositions are
developed with a preset temperature-time mode of curing and set of required physical and mechanical properties.
Properties of polymeric materials based on epoxy
resins are largely determined by the choice of curing
agents and curing conditions. Epoxy resins cured with
carboxylic anhydride are of a high glass transition tem-
perature, lower shrinkage, they are less toxic than those
cured with amines [1–6] (Table 1) Curing agents of this
group produce ﬂ exible cured composition with high vi-
bration and shock resistance, good dielectric properties,
high thermal and moisture resistance [4, 5]. Anhydride
curing compared to amine is less exothermic process
. For reducing the time of the anhydride curing and
temperature in the system catalysts nitrogen-containing
compounds or complexes with boron trifluoride are
introduced. Depending on the activity of a curing agent
and temperature complete curing can be achieved in time
from few seconds up to 2–3 hours .
In this work, the effect of temperature and catalyst
structures, amine–boron triﬂ uoride complexes on the time
of anhydride curing epoxy resin ED-20 and properties of
the resulted compositions was studied.
The epoxy resin ED-20 based on the diglycidyl ether
of 2,2'-bis(4-hydroxyphenyl)propane and hardener iso-
methyl tetrahydrophthalic anhydride (IMTHPA) were
selected as test objects.
The mole ratio of epoxy resin : hardener is 1 : 0.8 that
is the same ratio, which is used in the industry. Boron
triﬂ uoride with amines, whose content was about 3% by
weight of the composition, was selected as the curing
catalyst. We have studied a series of amines of differ-
ent nature (aliphatic and aromatic, primary, secondary
and tertiary) with a wide range of pK
A plasticizer TEG was introduced into the system to
obtain a homogeneous composition. The curing process
was carried out in the temperature range of 30–120°C.
A gelation time t
, which is inversely proportional to the
rate constant of the reaction, was selected as an indica-
tion of the curing rate. According to the theory of Flory
, the conversion of epoxy groups at gelation point
regardless of the structure of the catalyst and tempera-
ture is 60–70%. Thus, use of this value is suitable for
calculating the technological parameters of the curing
reaction (Table 1).
In the case of the reaction series of aliphatic-aromatic
amines (Table 1, 10–13) the gelation time decreases
with the basicity of amine in the studied temperature
range, while for aliphatic amines an inverse relationship
is observed (14 and 15). The Bronsted empirical
relationship  was calculated for assessing the effect