Page 157 - Handbook of Surface Improvement and Modification

152 Anti-cratering and Leveling

The addition of a leveling agent (polydimethylsiloxane-based leveling agent (EFKA
3030, BASF)) improved the pattern of poly(3,4-ethylenedioxythiophene):poly(styrene
sulfonate), PEDOT:PSS, droplet to be spread to reach the corners of the electrode area. 5
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The leveling agent effectively reduced the surface energy. The modified ink had the sur-
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face tension significantly reduced from 70.2 to 49.6 mN/m. The shape of the electrode
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improved with the addition of a leveling agent.
The effect of fluorosurfactant, copolymer latex, and crosslinker on the surface prop-
erties of floor polishes has been studied using atomic force microscopy with adhesion
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mapping. All three fluorosurfactants successfully leveled the styrene-acrylic formula-
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tions.
The distribution patterns of additives in self-leveling flooring compounds are the
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function of application, formulation, and climatic conditions. The self-leveling com-
pounds (also called underlayments) are low viscous mortars, which are hand-applied as
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thin layers of 1-10 mm on floor substrate (e.g., concrete, screed). Their purpose is to pro-
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duce a smooth and even substrate, on which a carpet or parquet can be applied. The
superplasticizers (casein or a synthetic superplasticizer) act as water reducing agents and
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provide flowing and leveling properties.
The color yield values of fabrics printed with reactive dyes decreased with the
increase of sulfonate groups, but the fixation and penetration of the reactive dyes on cotton
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fabric increased. The reactive dyes with fewer sulfonate groups were sensitive to alkalis
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and urea. The reactive dyes with more sulfonate groups were not sensitive to urea and
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had good leveling properties, penetration uniformity, and good wet fastness.
POSS dispersants enabled the preparation of dispersions with particularly high pig-
ment loadings, which exhibited liquid-like viscoelastic behavior and were sufficiently
flowable to provide proper leveling, uniform distribution of pigment particles inside dry
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coating, and excellent solar absorptivity. The shear-thinning or pseudoplastic behavior
should be reinforced with time-dependence, called thixotropy, which supports storage sta-
bility at zero shear and enables slower structure reformation, which results in a better flow
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and leveling. If the pigment volume ratio is increased the paint loses its ability to flow,
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causing problems with leveling.
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Leveling is a result of surface tension of the liquid. The surface tension acts to min-
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imize the surface energy of the coating by minimizing the surface area. Thin coatings are
slower to level than thicker coatings, and lower viscosity coatings are quicker to level than
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high viscosity coatings.
The colloidal particles are much smaller than the film thickness and influence the
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film rheology through a concentration-dependent viscosity and bulk diffusivity. The lev-
eling times are accurately predicted by the linear theory, even for a large amplitude distur-
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bances.
Screeds are construction materials used to correct surface defects and to level
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floors. Selection of superplasticizer resulted in a formulation with self-leveling proper-
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ties.
The starch-based polymers were used as potential dispersants in cement pastes and
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self-leveling compounds. The starch-sulfobutylene or starch-maleate can potentially
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replace casein in self-leveling compounds.