Neocryl, a new generation of water-based steel structural anti-corrosion coating ® XK-801 emulsion.

Abstract:
This paper introduces a new acrylic resin product suitable for corrosion protection of water-based steel structures, demonstrates its excellent early water resistance and salt mist resistance test results, and analyzes the principle of resin synthesis.
key words: water-based acrylic, anti-corrosion, early water resistance, salt spray resistance
in the field of industrial anti-corrosion coatings, solvent-based coatings for a long time occupied a large market share. However, with the continuous improvement of environmental protection requirements, the market share of solvent-based coatings has decreased year by year, replaced by the rise of water-based industrial anti-corrosion coatings

. Among them, water-based acrylic coatings account for a large proportion, because it has excellent dryness, hardness, weather resistance and so on. However, in the actual use of the Chinese market, often due to early water resistance or salt spray resistance is not good enough to make the promotion of water-based acrylic is limited.
this paper introduces a water-based acrylic resin product developed specifically for the Chinese market, which is tested for its early water and salt spray resistance according to the actual needs of the end customer.
experimental part
water-based film-forming substance
water-based acrylic emulsion A, solid mass score 40% (commercially available); water-based acrylic emulsion B, solid mass fraction 40% (commercially available); water-based acrylic emulsion Neocryl® XK-801, solid mass score 40% (DSM), its basic physical parameters such as table 1.
Other additives
wetting dispersants (BICK Chemical, Mingling); defoaming agents (Ewing Group, Bick Chemical); substrate wetting agents (Ewing Group); wetting leveling agents (Ewing Group); film additives (Dow Chemical); thickeners (Mingling, Dow Chemical); anti-rust agents (Asotec, France); anti-rust (Newbile).
preparation process
varnish
in a high-speed mixing state to add the raw materials in turn, all added and dispersed for 10 minutes.
color paint
grinding part in the medium-speed stirring state in turn to add the raw materials, grinding to the appropriate fine filter to be used, after the mixing part in the high-speed mixing state in turn to add the raw materials, all added and dispersed after 10 minutes of material.
water-based acrylic base formula
spainting
black finishes in one paint (PVC -20%)
grey finishes in one paint (extremely high PVC s 38%)
Table 2 - Water-based acrylic varnish base formula
Table 3 - Water-based acrylic black primer in one basic formula
Table 4 - Water-based acrylic resin gray base formula
Experimental instrument equipment
Dispermat CV3-plus high-speed dispersor, VAM Company; MS4002TS electronic balance, Mettle Toledo Company; W-101 spray gun, IWATA Iwata Company; Q-FOG salt spray corrosion tester, Ongkol Corporation.
test method
in accordance with the HG/T 5176-2017 "steel structure water-based anti-corrosion coating" standard requirements, the coating of the early water resistance, salt spray resistance and other tests.
results and discussion
early water resistance
early water resistance, that is, paint film in the absence of dry conditions of water resistance, used to reflect the actual construction of paint film in the outdoor rain, dew and other conditions of water resistance performance, is the Chinese market customers in the metal industry coating applications in the urgent need of key performance. Combined with the drying time of the end customer, the usual simulated drying time in the laboratory is 4 hours at room temperature, 24 hours at room temperature, 30 minutes at 50 degrees C baking, etc.
results of the varnish
substrate: polished cold-rolled steel plate
dry film thickness: 40um
drying conditions: room temperature self-drying 4 hours
bubbling time: 7 days
as can be seen from Figure 1, water resistance 7 After the day just removed, the XK-801 only lost light and whitening did not foam, two commercial competition in addition to the loss of light whitening have a large number of foaming;
results of the experiment on the black substrate
substrate: polished cold-rolled steel plate
dry film thickness: 40um
drying conditions: room temperature self-drying 2 hours
bubble time: 24 hours
Figure 2 - Neocryl® X K-801 black back cover in one paint early water-resistant
Figure 3 , Neocryl® XK-801 early water-resistant front and rear paint film micromorphological map
from Figure 2, water-resistant 24 hours later XK801 black paint film only slightly whitening, no foam rust and other phenomena.
in order to further verify the water resistance, we use a microscope to analyze the micromorphism of the paint film, and further confirm the water resistance of the product. The models of water resistance test, water resistance test and non-test were selected for comparative analysis. As can be seen from Figure 3, the appearance of the paint film before the water-resistant test is consistent with the standard, showing the appearance of a typical metal plate. However, there was no significant change in the paint film after water resistance testing, especially the absence of bubbles, indicating no water infiltration. This good water resistance further validates our conception in the polymer structure design of this product, that is, the introduction of self-assembly structure (see Figure 4), through the adjustment of the soft segment part, so that the polymer has excellent film-forming properties, in order to achieve a short drying time to improve the density of the paint film, prevent water gas seepage, thus achieving excellent paint film water resistance.
4 - Neocryl® XK-801 polymer self-assembly structure
salt-resistant
black substrate with paint (PVC - 20%) Experimental results
substrate: polished cold-rolled steel plate
dry film thickness: 100um
drying conditions: room temperature self Dry 7 days
salt-resistant fog time: 500 hours
Figure 5 , Neocryl® XK-801 black base in one paint salt-resistant fog
Figure 5 left-hand plate cross-section right-hand plate not crossed, after 500 hours of salt fog after a good surface, no foam rust, the spread of the fork less than 2mm.
gray finished paint (extremely high PVC - 38%)
substrate: polished cold-rolled steel plate
dry film thickness: 70um
drying conditions: room temperature self-drying 7 days
salt spray resistance time: 120 hours
Figure 6 - Neocryl® XK-801 gray substrate combined paint salt spray resistance
PVC38% is a very high PVC value for industrial paint, in such pVC, paint film salt spray resistance will be very large impact, common resins can only be done for 48 hours. Figure 6, the left side XK801 in 120 hours after the salt mist plate is good without foaming, cross spread less than 2mm;
the previous mention of the structural design of polymers, we introduced the concept of self-assembly, to achieve an increase in the density of lacquer film, and thus improve water-resistant salt spray performance. In addition, in order to meet the high PVC under the good performance, we further carried out targeted research. As we all know, in the high PVC, resin to powder encasing will inevitably have an impact on the overall performance of the paint film, and in order to improve the resin to powder encasing, we hope to introduce a certain nirch base, and powder to form a certain molecular force, and thus to help disperse the powder, Figure 7. At the same time, however, the hydroffinity of the carboxyl itself can lead to negative effects on resistance. To solve this problem, we have innovatively introduced the main nirch-based to the polymer side chain to minimize the impact of resistance while having good powder wrapping.
Figure 7 - Neocryl® XK-801 polymer chain segment introduces nihilism-based
conclusion
Neocryl® XK-801 resin with excellent early water and salt spray resistance, while maintaining good hardness while maintaining flexibility, it is sure to achieve great success in China's water-based industrial coatings market.
reference
. HG/T5176-2017 Water-based anti-corrosion coatings for steel structures
.