Russian Journal of Applied Chemistry, 2011, Vol. 84, No. 1, pp. 142−146.
Pleiades Publishing, Ltd., 2011.
Original Russian Text © O.G. Khelevina, E.I. Pukhova, 2011, published in Zhurnal Prikladnoi Khimii, 2011, Vol. 84, No. 1, pp. 142−146.
AND POLYMERIC MATERIALS
Metalloporphyrazines as Catalysts of Cross-Linking
of Liquid Siloxane Rubbers
O. G. Khelevina and E. I. Pukhova
Ivanovo State University of Chemical Technology, Ivanovo, Russia
Received April 7, 2010
Abstract—Cross-linking of liquid low-molecular-weight siloxane rubbers SKTN using metalloporphyrazines
[tin(II), iron(II), copper(II), cobalt(II) phthalocyanines, octaphenyltetraazaporphyrinatocobalt(II)] as catalysts
Si O Si OH
O Si OH
Si O Si
Si O Si
Si O Si
+ 4 ROH
Materials of reduced combustibility with a vulcanized
coating based on liquid low-molecular-weight siloxane
rubbers are of considerable interest for the development
of individual protection means . Along with reduced
combustibility, these materials exhibit high resistance
to water, oil, benzine, frost (–70°С), and heat .
Therefore, liquid siloxane rubbers show promise for the
development of protective materials.
The most suitable for preparing curable siloxane
coatings are liquid low-molecular-weight siloxane
rubbers with the molecular weight in the range 10 000–
000, because rubbers with the molecular weight
lower than 10
000 after curing do not exhibit the required
elasticity, and rubbers with the molecular weight higher
000 are unsuitable for application onto fabric
substrates because of high viscosity.
Cold-curable low-molecular-weight liquid siloxane
rubbers SKTN commercially produced in Russia contain
terminal silanol groups via which the rubbers can be
subjected to cross-linking by the polycondensation
The most widely used are two-component formula-
tions based on SKTN rubbers of various grades, con-
taining cross-linking agents and catalysts. Curing of
low-molecular-weight siloxane rubbers SKTN with tet-
raethoxysilane or ethyl silicates follows the scheme .
Various organotin compounds such as tin octoate,
dibutyltin dilaurate, dibutyldiacetoxy stannate, etc., are
used as catalysts for vulcanization of low-molecular-
weight siloxane rubbers SKTN. The common drawback
of two-component formulations based on liquid siloxane
rubbers SKTN and containing cross-linking agents and