Waterborne polyurethane (WUP) is prepared by using polyethylene glycol (PEG) and isophorone diisocyanate (IPDI) as the raw materials

2

2-bis (hydroxymethyl) propionic acid (DMPA) as the hydrophilic chain extender agent

1

2-propylene glycol (PDO) as the chain extender

HEA as end-capping reagent and triethylamine (TEA) as the neutralizer. The resin properties are characterized by thermal gravimetric analysis instrument and particle size analyzer. The results show that when the mass fraction of DMPA is 3%—6%

the PU resin has low molecular weight

good water solubility

good heat resistance and suitable particle size. In the preparation of water-based ITO etching ink

PU is the connection material

phosphoric acid or the compound of phosphoric acid and sulfuric acid is the etching agent

kaolin is the filler

defoamer and leveling agent are the additives. The properties of the ink are characterized. The results show that the best ink formula is that the mass fraction of etching agent is 25%—30%

the mass fraction of connection material is 30%—45%

the mass fraction of filler is 30%—45% and the mass fraction of additives is 1%. The best etching process is that the etching temperature of ITO film is 120℃

the etching time is 20 min and the ink-cleaning time is 50 s

while the etching temperature of ITO glass is 150℃

the etching time is 20 min and the ink-cleaning time is 50 s. The particle size distribution of the ink is 10—50 μm

the dehydration rate of the ink is just 1.12%—3.68% after 3 h

and the viscosity and pH of the ink are almost stable after 60 d. The etching ability of the ink does not reduce with increasing time

and the lines' image resolution of screen printing is significantly better than the commercially available water-based ink.