Abstract
In this study, a 2-pack isocyanate curing waterborne paint (without organic solvents) encapsulating dibutyltin dilaurate (hereinafter, DBTL) in nonionic surfactant micelles with an hydrophilic–lipophilic balance of 13–14 in advance releases DBTL when the micelles are collapsed at 80 °C or higher, whereby the curing progresses rapidly. On the other hand, the viscosity levels of the paint before and after being left at 40 °C for 1 h are almost the same. Organic solvents are mandatory for waterborne paints to provide paint and film properties, but they might collapse the micelles when they are formulated in the paint. In this study, we investigate whether the abovementioned paint containing organic solvents can develop switching functionality in terms of maintaining the storage stability at 40 °C and expressing a catalytic function at 80 °C to progress the curing. As a result, we find that if the solubility of the organic solvent in water at 20 °C is at least 10 g/100 mL and the boiling point is ≤200 °C, both curing and storage stability can be achieved.
Highlights
Thermosetting resins used in automotive body paint mainly consist of acrylic polymers containing hydroxyl groups and curing agents, such as isocyanate groups and melamine resins, to ensure coating performance
We investigated whether the abovedescribed actual paint system containing organic solvents can develop a switching functionality in terms of maintaining storage stability at 40 ◦C and imparting a catalytic function for curing progress at 80 ◦C
Organic solvents with high hydrophilicity and low boiling points are less likely to be incorporated into the micelles and have less significant effects on the behavior of DBTL in the micelles, which in turn is less likely to be released
Summary
Thermosetting resins used in automotive body paint mainly consist of acrylic polymers containing hydroxyl groups and curing agents, such as isocyanate groups and melamine resins, to ensure coating performance. The automobile body painting process consists of three coating layers, namely a primer surfacer, base coat, and clear coat, on an electrodeposited steel sheet Both the primer surfacer and the base coat comprise a curing system mainly composed of acrylic polyol and melamine resin [5], low-temperature (100 ◦C) baking is very difficult for melamine resin curing systems. In the acrylic polyol and isocyanate curing systems, an increased amount of catalyst such as dibutyltin dilaurate (DBTL) makes it possible to lower the baking temperature to 100 ◦C, while decreasing the time taken for curing [7].; while enabling low-temperature baking, the reactivity at room temperature increases, meaning the meaning the storage stability of the paint may deteriorate. The samples were prepared by adding Burnock DNW5500, acetone, and DBTL (the concentration of DBTL in the paint was 0.1 wt%, hereafter referred to as DBTL (directly added))
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
