This fluorine-containing acrylate modified water-based PU has the same performance as water-based fluorocarbons

Key words: anticorrosion coating modified waterborne polyurethane long fluorine side chain double crosslinking system

Background introduction

Metal corrosion is a serious problem that brings huge economic losses to countries all over the world every year

Due to the increasing pressure on environmental protection, the industrial application of solvent-based coatings is limited

Zhu Xiuling's team from the School of Chemical Engineering of Dalian University of Technology used polycaprolactone polyol, toluene diisocyanate, dimethylpropionic acid and hydroxyethyl methacrylate as raw materials to synthesize terminal double bond waterborne polyurethane prepolymer

research content

1.

Synthesis of waterborne polyurethane (WPU) prepolymers was carried out in a 250 ml four-necked flask equipped with a mechanical stirrer, spherical condenser tube and thermometer

2.

Self-crosslinking fluorine-containing acrylate-modified waterborne polyurethane (CFWPUA) composite emulsion was prepared by soap-free seed emulsion polymerization

3.

The base material is Q235 steel plate (120mm×50mm×0.
5mm), which should be sanded and cleaned with ethanol before painting, so that the surface is free of dust particles, oils and surface oxides
.
The CFWPUA emulsion was applied to the surface of the Q235 steel rod-like coating
.
The coating was then transferred to an oven and baked at 45°C for 4 days, then the temperature was raised to 60°C for an additional 2 days to obtain the final coating
.
The thickness of the coating is about 45±5 μm, and the coatings used in this experiment are all prepared by the above method
.

4.
Preparation of Self-Crosslinking Fluorine-Containing Acrylate-Modified Waterborne Polyurethane Coatings

In order to obtain the hybrid film, an appropriate amount of the composite emulsion was poured into a PTFE mold with a size of 20 × 20 × 3 mm and cured at 45 °C for 4 days, then the temperature was increased to 60 °C and cured for 2 days
.
The obtained film will be used as a sample for necessary tests such as surface morphology test and water absorption test
.

in conclusion

In conclusion, the prepared modified waterborne polyurethane coating has excellent anticorrosion performance
.
The external hydrophobic surface formed by the migration of long fluorine side chains during the curing process, combined with the internal double cross-linking system, effectively prevents the rapid penetration of water molecules and corrosive media into the surface of the metal substrate, and meets the long-term anti-corrosion requirements
.
When the GMA content was 5 wt% and the DFMA content was 7.
5 wt%, the water absorption of the coating film decreased to 7.
91%, and the water contact angle increased to 102.
5°, showing excellent water resistance
.
In the electrochemical impedance spectroscopy test, the coating maintained a high coating resistance for 12 days, acting as a physical barrier and effectively protecting the metal substrate
.
Compared with other commercial coatings, the corrosion resistance of modified waterborne polyurethane coatings has been improved to a certain extent
.
In addition, the modified waterborne polyurethane coating has excellent mechanical properties, thermal stability and other properties, which can meet the needs of practical applications
.
The next step of research can start from ensuring the long-term stability of the long fluorine side chain, avoiding its surface reorganization under long-term use conditions, so as to further improve the long-term anti-corrosion performance of the coating
.

References: Wang X, Cui Y, Wang Y, etal.
Preparation and characteristics of crosslinked fluorinated acrylatemodified waterborne polyurethane for metal protection coating[J].
Progress inOrganic Coatings, 2021,158:106371.