Selection of Dispersant in Waterborne Light Anticorrosive Coatings

As the country's requirements for environmental protection are becoming more and more stringent and people's awareness of environmental protection is increasing day by day, water-based coating technology is developing rapidly, and the water-based coating market is expanding rapidly

In recent years, the water-based coatings market has continued to develop.

In order to improve the performance of all aspects of water-based light anti-corrosion coatings, Huihong Additives has done relevant research on the effect of dispersants on the performance of water-based light anti-corrosion coatings

The pigment dispersion process is shown in Figure 1 below

The three processes of pigment dispersion:

1.

2.

3.

Experimental part 

Experimental materials and equipment

Dispersant HP2466, dispersant HP2405, competitive dispersant, water, dimethylethanolamine, iron red, barium sulfate, zinc phosphate, mica powder, defoamer, emulsion, alcohol ester twelve

Gloss meter, constant temperature water bath, 100 grid knife, tape, oven, sand mill, glass bottle, wire rod

Water-based paint preparation

Color paste preparation

Add dispersant, water and DMEA according to the color paste formula in Table 1 and stir evenly, add pigments and fillers while stirring, and finally add defoamer to pre-disperse for 30 minutes
.
Then add it to the sand mill to grind the fineness to about 10-15μm
.
Part of the color paste is stored for heat and part is used to make paint
.

Paint preparation

According to Table 1, add the emulsion, alcohol ester twelve, and water into the mixture, stir evenly, and leave it for the next day to form a film
.

Table 1 »Water-based light anti-corrosion coating bottom surface integration

Paint film preparation

Scratch the sample with an 80μm wire rod, leave it for 24 hours, and test the paint film adhesion
.

Scratch the sample with an 80μm wire board and leave it for 2 hours to test the early water resistance of the paint film
.

Water-based coating performance test

Color paste performance test

Color paste grinding efficiency test, compare the fineness of color paste under the same grinding time
.

Color paste viscosity test, use a rotary viscometer to test the color paste viscosity at the same temperature
.

To test the storage stability of the color paste, place it in a 50 degree oven for 7 days to observe whether the color paste has water separation, hardness, and coarseness
.

The addition of different dispersants affects the performance of the color paste
.

Coating performance test

Paint stability test

Paint film gloss adhesion test, 80μm wire rod prepared paint film and dried for 24 hours to test gloss and adhesion
.

In the early water resistance test of the paint film, the paint film was prepared with an 80μm wire rod and dried for 2 hours to test the water resistance
.

Gloss test of dispersant in different light anticorrosive emulsions
.

Experimental results and discussion 

As shown in Figure 2, as the grinding time increases, the fineness of the pigment decreases.
Among them, the fineness of the dispersant HP2466 decreases the fastest and the grinding efficiency is the best
.
Therefore, a good dispersant can improve grinding efficiency, thereby improving work efficiency, further reducing energy consumption and saving costs
.

Figure 2 »Grinding efficiency curve

Different dispersants have different wetting and viscosity reduction and stability of pigments and fillers, so dispersants will have a greater impact on the anti-settling of the color paste
.
It can be seen from the thermal storage water separation experiment of the color paste that, as shown in Figure 3, the dispersant HP2466 has less water separation and the best anti-settling, the dispersant HP2405 has more water separation, and the competing products have the most water separation
.

Figure 3 »Variation of thermal storage water of color paste with time

The effect of the use of different dispersants on the viscosity reduction effect, grinding efficiency and storage stability of the color paste is shown in Figure 4.
Dispersant HP2466 has the best comprehensive performance, and HP2405 has the best viscosity reduction effect
.

Note: The higher the grade, the better the performance of a certain item (the grades in this article are all comparative evaluations under the same conditions)

Figure 4 »Color paste performance grade chart

It can be seen from Figure 5 that the added amount of dispersant will also affect viscosity reduction, grinding efficiency, and stability.
When the added amount of dispersant reaches 1.
5%, the overall performance is the best
.
A moderate amount of dispersant can not only achieve the best overall performance, but also save costs
.

Figure 5 »The effect of the amount of dispersant added on the colorant

It can be seen from Figure 6 that HP2466 has higher gloss in different water-based light anticorrosive acrylic emulsions, which shows that HP2466 has strong compatibility with water-based acrylic emulsions and good versatility
.

Note: The higher the level, the better the performance

Figure 6 »Gloss of dispersant in different emulsions

It can be seen from Figure 7 that HP2466 has better water resistance, HP2405 has general water resistance, and competing products have poor water resistance
.
Dispersants have different dispersing properties for pigments and fillers, their compatibility with resins, and the water resistance of dispersants themselves.
Some dispersants have strong hydrophilicity, which seriously affects the water resistance of the paint film
.

Figure 7 »Water resistance of paint film

It can be seen from Figure 8 that different dispersants have very different effects on paint film adhesion
.
The dispersant has different encapsulation properties for pigments and fillers, as well as its own wetting properties and different compatibility with resins, etc.
, which affect the paint film adhesion
.
Dispersant HP2466 has excellent wetting properties, good compatibility with resins, and the best paint film adhesion
.

Figure 8 »Paint film adhesion

It can be seen from Figure 9 that the overall performance of the paint prepared with HP2466 dispersing pigments and fillers is the best.
Because of the wetting and viscosity reduction of the pigments and fillers by the dispersant, the compatibility of the dispersant with the resin and the different hydrophilicity of the dispersant itself, etc.
The stability of the coating, the gloss of the paint film, the effect of the board surface and the water resistance will all be affected by the dispersant
.

Figure 9 »Different dispersants have different compatibility with resins

It can be seen from the above experimental results that Huihong water-based dispersant HP2466 has strong versatility, wide application range, high grinding efficiency and good stability
.
HP2466 has excellent performance in all aspects, especially in water-based light anti-corrosion coatings, showing excellent wetting and dispersing properties, good water resistance, and good compatibility
.
The HP2466 dispersion color paste has excellent versatility for various water-based resins.
It is suitable for acrylic emulsions, secondary dispersions, polyurethane systems, and water-based medium and long oil alkyds, etc.
It exhibits higher gloss and better resin systems The effect of the board surface
.
HP2405 is excellent in dispersing pigments and fillers in water-based light anti-corrosion and reducing viscosity
.

Summarize 

This article discusses the effects of different dispersants on the properties of color pastes and coatings.
Dispersants affect the viscosity reduction, grinding efficiency and storage stability of color pastes
.
The dispersant will also affect the stability of the paint, the gloss of the paint film, the adhesion of the paint film and the water resistance of the paint film
.

The addition amount of dispersant will also affect the performance of the paint film, and each dispersant will have an optimal addition amount
.
Choosing a good dispersant can not only make the performance of the paint film meet the requirements, but also improve work efficiency, reduce energy consumption, and save costs
.
HP2466 has excellent comprehensive performance in water-based light anti-corrosion and strong versatility.
HP2405 has excellent dispersion of pigments and fillers in water-based light anti-corrosion and viscosity reduction
.

references

[1] Geng Xing.
Handbook of Modern Waterborne Industry [M].
Beijing: Sinopec Publishing, 2007 (06): 50-51

[2] Liu Rui, Zhuang Zhenyu, Zhang Hanqing, etc.
, Development of water-based acrylic topcoat for containers[J].
Paint Industry, 2019, 49(8): 35-40.

[3] Liu Gui, Development of silicone modified acrylic emulsion and its water-based anticorrosive coating

[D].
East China University of Science and Technology, 2012, 2.