Surface modification of fabrics by RF plasma for ink absorption

The physical and chemical properties of cotton and polyester fabrics were modified by three types of gas plasma pretreatment to improve ink absorption of pigmented water-based inks. Oxygen (O2), nitrogen (N2), and sulfur hexafluoride (SF6) gas plasmas were used in this research. Effects of each gas plasma parameter, namely, power, exposure time, and gas pressure during exposure were investigated on physical and chemical properties of the treated fabrics. X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy were used to identify functional groups on the fabrics. Attenuated total reflection Fourier transform infrared spectroscopy was used to study the functional groups of the pigments. Color spectroscopic technique was used to investigate color ink strength absorbed on the printed fabrics. The results indicated that O2 plasma and N2 plasma increased the fabric hydrophilicity and surface energy with the increases of C-O, C=O, and O-C=O groups on the fabrics after the treatment by O2 plasma. C-N and O=C-NH2 groups were given by the N2 plasma. The increased hydrophilicity of the fabric by O2 plasma induced greater water-based ink absorption than by N2 plasma. The K/S values were increased as well when comparing with those of the untreated fabrics. The SF6 plasma-treated fabrics were hydrophobic which caused less ink absorption. The fabric surface roughness, caused by plasma etching increased fabric surface areas to capture more ink and thus increased more ink adhesion. The cotton fabrics exhibited higher ink adhesion and wider color gamut after the O2 plasma treatment comparing with those from the N2 plasma. More ink adhesion and wider color gamut were found on printed polyester fabrics with N2 plasma treatment than the O2 plasma treatment did.