СЕКЦИЯ 6. «ЗОЛЬ-ГЕЛЬ МАТЕРИАЛЫ ДЛЯ ПРИМЕНЕНИЙ В ОБЛАСТИ ОХРАНЫ ПРИРОДЫ, СЕЛЬСКОГО ХОЗЯЙСТВА И БИОМЕДИЦИНЫ» 81
gy of water-dispersive film-formers, latexes of homo- and copolymers of vinyl acetate, vinyl chloride,
ethylene, acrylates, styrene and some other monomers are widely used. Such aqueous dispersions of
polymers are called synthetic. There are also artificial dispersions obtained by emulsifying oligomers
at a temperature above their softening point or solutions of oligomers or polymers (sometimes with
subsequent distillation of solvents). Film-formers in such dispersions can be both the oligomers and
polymers listed above, and alkyds, epoxies, polyurethanes, bitumens, drying oils, etc [2].
In traditional paints and varnishes, about 50% of the mass of the material is made up of organ-
ic solvents, which are irretrievably lost during the production of coatings. The toxicity of most of them
and the fire and explosion hazard necessitate the installation of powerful ventilation systems in paint
shops and additional installations for cleaning gas emissions into the environment. One of the ways to
solve the problem of excluding organic solvents from the formulations of paints and varnishes is to
create aqueous film-forming systems [3].
Water-based paints and varnishes can be divided into two groups: water-dispersive film-
forming systems, which are an emulsion of a film-former in water, and water-soluble film-forming
systems, which are an aqueous solution of a film former. Water-based paints and varnishes of both
types have a relatively high surface tension, which dictates the need for special preparation of the met-
al for painting to ensure the uniformity of the coating and its good adhesion [4].
As a result of the literature analyzes and laboratory studies carried out on the basis of the
Tashkent Scientific Research Institute of Chemical Technology, a method was developed for obtaining
a water-emulsion-type film former based on epoxy resin. The method of obtaining an emulsion of an
epoxy phase in an aqueous medium is based on the emulsification of epoxy oligomer molecules using
hydroxypropyl methylcellulose and polyvinyl alcohol [5]. In this work, we investigated the formation
of a gel fraction of an epoxy polymer in the form of a dispersed phase in an aqueous medium. Re-
search has been carried out on the effect of the UP-606 curing accelerator for epoxy polymers on the
curing time of an epoxy film-former of water-based paint. The formation of a coating from an aqueous
emulsion occurs as a result of its coagulation on a substrate. Figure 1 shows the change in the curing
time of an epoxy film former on an aqueous emulsion depending on the amount of curing accelerator
added. Solidification takes place at a temperature of 25
⁰
С. To determine the effect of the accelerator
of curing of epoxy polymers UP-606 on the duration of curing, the maximum degree of curing of the
epoxy film-forming agent is conventionally taken. This degree of hardening is 87% of the gel fraction
in the cured epoxy film former. To determine the content of the gel fraction in the polymer, the
Soxhlet method was used. The extraction apparatus is assembled by this method. To accelerate the
extraction and more complete extraction of the monomer, it is necessary to grind and dry the investi-
gated product.
Fig.1. Dependence of the solidification rate on the concentration of the accelerator
The material should be dried without access to air in a vacuum thermostat or in a stream of
carbon dioxide or nitrogen. A weighed portion of the product in an amount from 0.7 to 1.5 g is
weighed on a balance with an accuracy of 0.001 g and placed in an envelope made of filter paper. The