Sorry, that content could not be found

Error 404

We couldn't find https://www.paint.org/sso/login?RelayState=https%3A%2F%2Fwww.paint.org%2Farticle%2Fnew-marine-primer-reduces-voc-emissions-by-80-90%2F

Here's some content that might match what you're looking for, or you can perform a search.

Novel Cashew Nutshell Liquid-based Waterborne Curing Agents Designed for High-Performance and Low-VOC Protective Epoxy Coatings

[…] is suitable for high solids (>60% solids) waterborne formulations. It is always desirable that a paint system exhibits fast-cure performance while having a long work window (pot life) for easier application, though this is usually a difficult task to accomplish. For example, CNSL-based WB-C curing agent has excellent fast-cure properties (less than 2 h of dry-hard time at 25°C) with various solid epoxy dispersion resins. However, as shown in Figure 5, its average pot life is around 1.5 h (displayed as red dot), which can be considered short for some applications. Through better design of the polymers’ structures, new waterborne curing agents WB-A and WB-B exhibit the improved properties with fast cure and longer pot life. As indicated in Figure 5, WB-A and WB-B could achieve dry-hard times of 3 h or less with both Resin 1 and Resin 3 while providing extended pot lives of 3.5 h. The competitive-based system (COM) also shows long pot life but was slower in dry-hard times. The Persoz hardness data from Figure 6 confirm that WB-A and WB-B systems deliver faster hardness development than COM-based systems. Moreover, the fast-cure properties of WB-A and WB-B could benefit wet-on-wet topcoat applications, as presented in detail later in this article. Part II: Waterborne Primer/Mid-coat Systems Based on New WB-A and WB-B Curing Agents Excellent long-term corrosion protection is a key property required in waterborne epoxy primer systems and mid-coat systems; however, it is also the most challenging to achieve. In this study, newly developed WB-A and WB-B curing agents were evaluated to assess their anti-corrosion performance after extended salt-spray exposure. Different performance aspects, such as rust or blisters on field, and creep along the scribe line, were checked after certain exposure intervals, and wet adhesion was also conducted on the test panels after 800 h of salt-spray exposure. In Table 3, the formulations of three low-VOC waterborne primer systems, MC #1, MC #2, and MC #3, were listed based on WB-A, WB-B, and WB-C curing agents, respectively. For comparison purposes, all three primer systems were formulated with the same solid epoxy dispersion (Resin 3), at similar solids (around 57%), with comparable pigment volume concentration (PVC from 27% to 30%), and using the same 1.25 stoichiometric ratio. It can be seen that VOC values for those waterborne primer systems are less than 75 g/L. The anti-corrosion performances of MC #1, MC #2, and MC #3 formulations were assessed in direct-to-metal (DTM) primers. Those primer systems were directly air sprayed to various nonpretreated metal substrates, such as SA 2.5 blasted steel panels, cold rolled steel (CRS) panels, galvanized steel panels, aluminum alloy AA 2024 T3 panels, and stainless steel panels. Two cure conditions were used for those waterborne primer coated panels: seven-day RT cure or one- to two-hour bake in a 60°C oven. The final dry film thickness (DFT) of the waterborne primer films after cure was around 55 to 80 μm. Test panels were taped or coated on the back and edges before being placed into the Q-Lab Q-FOG chamber for ASTM B-117 test. Figure 7 shows the panel images of MC #1, MC #2, and MC #3 systems after about 1000 h of salt-spray exposure and after an 800-grit sandpaper was used to remove surface rust stains. Those films were applied over SA 2.5 sand-blasted steel substrates with about 60 to 75 μm DFT. It can be seen that only some small blisters formed near the scribe lines of the WB-A system, and the coating still has very good adhesion to the steel substrate along the X-shaped scribe lines. The WB-B system has smaller blisters in comparison to the WB-A system, but that might be due to 200 h less salt-spray exposure time. The COM system also shows good anti-corrosion performance, with very few blisters formed on the film surface, but some creeps observed along the scribe lines. As part of this study, one can also notice the significant impact of film thickness on long-term anti-corrosion performance, especially over sand-blasted panels. For example, MC #1 formulation was applied to panels at various DFT of 37 μm, 50 μm, 65 μm, and 100 μm, and then exposed in the salt-spray chamber. After 500 h of salt-spray exposure, the system with 37 μm DFT already showed severe rust and blisters, while the other three systems still had intact films; up to 1100 h, the system with 50 μm DFT exhibited more dense blisters along the scribe line than the system with 65 μm DFT, but the system with 100 μm DFT showed no blisters. As expected, higher film thickness provides better and longer anti-corrosion protection to metal substrates. In addition, the test results in this study suggest that the impact of film thickness of waterborne primer systems on anti-corrosion performance could become more significant over sand-blasted steel panels. That is probably because waterborne primer systems tend to penetrate and settle in the bottom crevices of the rough surface of sand-blasted steel panels, which results in some weak areas with much lower film thickness where corrosion can start. Figure 8 exhibits the panel images of MC #1, MC #2, and MC #3 systems after about 1000 h of salt-spray exposure and after removal of surface rust stains with an 800-grit sandpaper. Those waterborne primer systems were applied on CRS panels with DFT of about 75 μm. Blisters were only observed along the scribe lines for all three systems, but the adhesion of coating films to CRS substrates along the scribe lines was not excellent; some underneath creeps developed with the widths of 3 mm, 1.5 mm, and 3.5 mm for MC #1, MC #2, and MC #3 systems, respectively. These test results indicate the new waterborne primer systems could provide very good corrosion protection on CRS, but it is still a major challenge to achieve superior adhesion to steel substrates with a smooth surface profile after long-term salt-spray exposure. Next, this study evaluated the anti-corrosion and adhesion properties of the new waterborne curing agents on various metal substrates commonly used in some industrial coatings applications that include aluminum alloys, stainless steel, and galvanized steel. In general, good adhesion, and therefore long-term corrosion protection to these substrates, could be difficult to achieve, especially with low-VOC formulations. Figure 9 displays the panel images of MC #1, MC #2, and MC #3 systems over aluminum alloy AA 2024 T3 substrates after 2018 h, 1852 h, and 2018 h of salt-spray exposure, respectively. (The panel surfaces were sanded via 220-grit sandpaper followed by an acetone rinse and paper towel cleaning.) It can be seen that MC #1 and MC #3 systems exhibited excellent protection properties with only a few very tiny blisters formed along the scribe line after 2018 h of salt-spray exposure; the MC #2 system also presented good anti-corrosion properties with no blisters and delamination after 1800 h of salt-spray exposure on the panel field, though some small blisters formed along the scribe line. Wet adhesion was measured on the test panels (top right side of each panel) that had been exposed in the salt spray chamber to endure the continuous attacks of ions and water for more than 800 h; therefore, the excellent wet cross-hatch adhesion observed from three primer systems over AA 2024 T3 indicates excellent long-term corrosion protection. The panel images of MC #1, MC #2, and MC #3 systems applied over stainless steel substrates after about 1000 h  of salt-spray exposure are shown in Figure 10. There were no blisters or delamination observed for the three systems. Furthermore, MC #1, MC #2, and MC #3 systems were also applied over galvanized steel substrates that were simply wiped with acetone. Figure 11 displays the panel images of those systems after about 1000 h of salt-spray exposure: MC#1 system had two to three large blisters and medium dense blisters with size of 6 to 8 along the scribe line; MC #2 system showed two large blisters and some blisters with size of 8 along the scribe line; and MC #3 system formed much larger and denser blisters from the center scribe line to both sides. Results demonstrate that in comparison to other substrates evaluated in this study, the blisters formed on galvanized steel panels were much more severe for similar duration of salt-spray exposure. Even though galvanized steel was the most challenging substrate, MC #1 and MC #3 systems still exhibited fairly good wet adhesion performance and could be good options for formulators. Some formulation study to improve the corrosion protection on galvanized steel substrate is reported in Part III. Table 4 summarizes the dry and wet cross-hatch adhesion of MC #1 and MC #2 primer systems over four types of metal substrates: nonpretreated bare CRS with a smooth mill finish, galvanized steel wiped with acetone, AA 2024 T3 panels sanded via 220-grit sandpaper followed by acetone rinse and wiped, and stainless steel with no surface preparation. The dry adhesion values were obtained on the cured panels that were not exposed to salt spray, while the wet adhesion values were measured on panels after exposure in the salt spray chamber for more than 800 h. It can be seen that MC #1 and MC #2 primer systems had very good dry adhesion regardless of the type of metal substrate used; after being exposed to salt spray for more than 800 h, the wet adhesion of MC #1 and MC #2 systems over aluminum alloy substrate was still excellent. Over stainless steel substrate, MC #1 system still maintained excellent wet adhesion while MC #2 system showed a little drop to 3B. Both MC #1 and MC #2 systems still achieved 3B wet adhesion over bare CRS. The major difference in performance between MC #1 and MC #2 systems was observed when applying over galvanized steel substrates: MC #1 system still provided good wet adhesion of 4B, but MC #2 system lost adhesion after long salt-spray exposure. The test results in Table 4 demonstrate that the two new waterborne samples could provide excellent dry and wet adhesion over various metal substrates, except MC #2 system showed poor wet adhesion over galvanized steel substrate. The excellent adhesion properties of new waterborne samples could further benefit the long-term corrosion protection of different metal substrates. Part III: Wet-on-Wet Properties Quick self-recoat or recoatability with PU coatings is a highly desirable property in industrial applications, such as transportation coatings, agricultural, construction and earth-moving equipment coatings, and rail car coatings. Very short recoat intervals between the application of primer and the next coating layer are required, such as 30 min or less at RT or elevated cure conditions. Since the primer may not be fully dried when the next coat is applied, this cure process is usually called wet-on-wet application. If a primer system is slow in cure or has poor compatibility with PU topcoat, it will most probably result in a dieback issue, which means that the cured PU topcoat no longer has its original high gloss and may show poor adhesion to the primer system. The wet-on-wet topcoat performances were evaluated on the MC #4 system based on WB-A curing agent and Resin 3; the MC #4 primer system had VOC of less than 75 g/L. The primer system was applied via air spray over CRS substrate at a wet film thickness of 50 to 65 mm. The test panels were set up in six groups: the panels in Groups #1 to #3 were cured at RT for 15, 30, and 45 min, respectively. Meanwhile, the panels in Groups #4 to #6 were baked in a 60°C oven for 15, 30, and 45 min, respectively. Subsequently, a commercial 2K solventborne PU system was applied over all six groups of panels via air spray. After a 24-h RT cure, the glosses of the PU top-coated panels, as well as their adhesions between the primer and PU topcoat, were measured and are listed in Table 6. Photo images of those panels after cross-hatch adhesion tests are shown in Figure 12. Those test results reveal that MC #4 system could maintain high gloss retention (>98%) and excellent adhesion (5B) to the commercial PU topcoat regardless of the cure conditions […]

Graphene in Coatings: Overcoming the Challenges to Reap the Benefits

[…] Council, June 25, 2020. PCE International, “Graphene goes to sea,” Global Newswire, April 16, 2020. https://www.pce-international.com/2020/04/16/graphene-goes-to-sea/ (accessed September 10, 2020). GrapheneCA, “GrapheneCA’s Breakthrough Antimicrobial Coatings Passes Primary Independent Test,” May […]

Members Only International Affairs Report

[…] of the regulation, ACA joined with two European counterparts — the European Council of the Paint, Printing Ink and Artists’ Colours Industry (CEPE) and the British Coatings Federation (BCF) — […]

Silyl-Containing Polyurethanes that Selectively Disassemble with Fluoride Salts

[…] 907 (2013). 3. (a) “EPA Bans Consumer Sales of Methylene Chloride Paint Removers, Protecting Public,” https://www.epa.gov/newsreleases/epa-bans-consumer-sales-methylene-chloride-paint-removers-protecting-public, 15 March 2019, (b) “EPA’s Methylene Chloride Ban Excludes Workers,” https://www.webmd.com/lung/news/20190318/epa-methylene-chloride-ban-excludes-workers, 18 March 2019. […]

Architectural Coatings

One Coat Many architectural paints — both interior and exterior — are now paint and primer in one product, which allows for a paint-job with fewer coats, translating to greater […]