Primary screening, fine screening and cost reduction and efficiency enhancement of dispersants for water-based anticorrosive coatings

Screening of water-based antiseptic paint dispersants
The difficulties of water-based anti-corrosion coating formulations in pigment dispersion are: 1. There are many types of pigments used, high content is difficult to achieve efficient dispersion; 2. The addition of dispersant requirements is best not to affect the corrosion performance of finished coatings; 3. The cost requirements are higher under the conditions of meeting the general performance of the coating. All of the above put forward high requirements for the precise screening of dispersants.
we know exactly how to screen for these dispersants? Where should I start evaluating and optimizing? We will share our experience in screening such dispersants in an application case below

.
1, first of all, according to the type of primary screening dispersant for dispersion needs
Generally speaking, water-based antiseptic coatings preferred general-purpose polymer dispersants: anchoring the base group, and pigment binding force is large, while solventization chain and water have sufficient affinity, with good compatible, polymer chain in the water can fully stretch to form an effective space resistance, very conducive to dispersion and stability; Such dispersants can be used as the object of primary screening.
2, further fine screening work includes: dispersion, de-stick effect, color display, storage stability and moisture and heat resistance
® Molecular dispersants, for example, do further fine sieve work: through the limit method to assess their performance in the water-based acrylic co-grinding system (indistin/titanium white powder/ talcum powder, etc.): mainly including dispersion, anti-stick effect, color display, storage stability and moisture-resistant heat resistance. Detailed assessment methods and results are shown below.
ZETASPERSE® 3800 Introduction
1, anti-stick effect
In the pigment grinding process, we test the different additions under the dispersant's anti-stick effect.
, as the amount of dispersant increases, the viscosity decreases and then increases. Usually in actual production, we do not use excessive dispersants, but use them as little as possible. Therefore, we designed experiments to observe the effects on viscosity by gradually reducing the amount of dispersants. Visible: With the reduction of dispersant dosage, viscosity is constantly increasing, even difficult to disperse, as shown in Figure 1.
Figure 2, different additions of dispersants corresponding to the viscosity of the abrasive slurry
relative to, at 0.75% dosage, the viscosity of commercially available products increased significantly, scraper fineness also correspondingly varied, while ZETASPERSE® 3800 showed a better anti-adhesive effect, the fineness is always maintained at less than 30 m.
ZETASPERSE® 3800 showed excellent anti-stick effect at 0.75% dosage
2, color display
after preparation into paint, we tested the color display effect of dispersants under different additions.
with the increase of dispersant dosage, the color display of the coating film will be significantly improved. Objective evaluation of color display can be achieved with visual or instrument measurement. In particular, the better the color spread, the darker the blue phase, i.e. the greater the negative value of b measured by the instrument (shown in the figure below).
Figure 3, different amounts of dispersants corresponding to the blue phase b value of the paint film
(the greater the value, the better the blue
phase
®
3, storage stability
after 50 degrees / 14 days of storage, we assess the storage stability of finished coatings.
Figure 5, the apparent effect of the coating after heat storage
the surface of the coating of the commercially available dispersant has a small amount of floating color phenomenon, such as the above figure, and in 0.5% and 0.75% dosage, there is a slight soft subsidon, while the use of ZETASPERSE® 3800 paint before and after storage basically did not change.
4, moisture-resistant heat
after 50 degrees / 7 days of heat resistance testing to assess the effect of dispersants on corrosion resistance.
commercially available dispersants at 0.5% and 0.75% dosage, the surface foaming phenomenon occurred, and ZETASPERSE®3800 resistance is significantly better. For water-resistant industrial paints, dispersants not only disperse a variety of pigment fillers, but also require certain resistance requirements, while ZETASPERSE®3800 has little effect on the corrosion resistance of water-resistant industrial paints.
3, finally: clever use of compounding to reduce the overall cost
In the actual paint, we will also recommend through the main selection of a polymer-type dispersant, such as ZETASPERSE® 3800, while re-matching other medium molecular weight, wetting performance of better cost-effective dispersants (e.g. TEGO® Dispers 747W, TEGO® Dispers 760W, TEGO® Dispers 740W, etc.) can improve grinding efficiency, reduce the combined cost of formulations, and have been studied to have limited effects on suitable complex pairing resistance, and even improve color display.
shown in the image below, the clever 1:1 rematch even shows a better color display.
Figure 6, different dispersants corresponding to the blue phase b value of the paint film
(the greater the absolute value, the better the blue phase


Among them: ZETASPERSE ® 3800 shows excellent viscosity effect, viscosity stability, color display, storage stability and moisture and heat resistance. In the actual paint, the appropriate combination of cost-effective dispersants can also reduce costs, the impact on tolerance is limited, the color display even has an improved role.
.