Swagata Chakraborty, Jaydeb Gayen, Akash Tarawal, Berger Paints India Ltd.
Abstract
The term “renewable” is generally applied
to those technologies and energy resources whose common characteristics are that
they are non-depletable or naturally re-
plenishable.1 Albeit, a major contribution from renewable resources comes in
the form of energy; other uses derived
from these resources also have equally
significant importance. This article deals
with a “tree-extract” called ‘Sweet Sap’
which can be used as an emulsifier for
making a water-in-oil emulsion leading
to the development of low-VOC solvent-borne enamels. This emulsion is made
using mechanical shear. Immiscibility
arising from the difference in surface tension between the two liquids is reduced
by using this emulsifier. The ‘Sweet Sap’,
by virtue of having both polar and non-polar ends, adsorbs to the water at one
end and non-polar liquids such as oils at
the other end and, as a result, significantly reduces the interfacial surface tension.
Two conventional emulsifiers available
in the market were used to compare the
properties of the emulsions and the paints
made with it. The water-in-oil emulsion
without emulsifier was also studied in order to understand the role of emulsifier
alone. Performances were evaluated both
in white and colored shades, including
their storage stability. The newly used
tree-extract in its natural “green-form”
was found to be very promising and effective not only from a qualitative point
of view, but also because it has enormous
potential to use green technology and
gain financial dividends.
Introduction
As the growing thrust on renewable energy has been intensified by government,
scientists are trying to find different renewable resources in different fields as
these are one of the focused verticals
which will drive our future growth and
development. This article deals with a
‘tree extract’ called ’Sweet Sap’ that was
used as the emulsifier for ‘water-in-oil’
emulsions, which were then employed as
a binder to formulate low-VOC enamels.
The performance of Sweet Sap was evaluated against two commercial emulsifiers,
and in a system without emulsifier to understand the role of this sap.
Emulsions are basically dispersions of
one liquid phase in another immiscible
liquid phase made with the application
of mechanical shear. Immiscibility arises
from the difference in surface tension
between the two liquids which requires
significant reduction for the emulsion to
remain stable. This reduction of surface
tension is achieved by using surfactants.
Surfactants having both polar and non-
polar ends adsorb to the polar liquids
such as water at one end and non-polar
liquids such as oils at other end and, as a
result, significantly reduce the interfacial
tension at the interface.
The stability of water-in-oil emulsions
was evaluated from their extent of separation and their loss of viscosity on storage. The paints made with the emulsions,
however, have been evaluated in detail,
particularly where emulsion can influence properties like viscosity and its loss
on storage, dispersion on storage and pigment flocculation and syneresis. Although
Use Of New Renewable
Resource For Low VOC Enamel
Figure 1 : FTIR spectra of standard additive 1 and Sweet Sap; differences are noted by superimposing
(interfering) waves in the fingerprint region.
