| Currently, aqueous polyacrylic emulsion has become one of the major types of binders used widely in pigment printing, because of its many excellent properties, such as good diaphaneity, excellent rubbing fastness, water resistance, weather resistance, affinity to pigments and low cost. However, it also showed poor performance as regards chemical resistance and toughness. In addition, it was brittle under freezing and viscous under warming when it was used for fabric pigment printing. So, serious problems of domestic pigment printed fabrics are hard handle and low fastness. So far high quality polyacrylic products still need a mass of importation. In order to solve these problems, two kinds of modified polyacrylic emulsion were synthesized in this research, with which pigment printing products were prepared in this paper. This research can offer guidance for production and application of pigment printing ink.At first, core-shell polyacrylic emulsion with hard core and soft shell was prepared via structure and property design of emulsion particles by introducing a small quantity of functional monomer, selecting emulsifiers and initiator and emulsion polymerization method. The microstructure of the emulsion particles was characterized by Fourier transmission infrared (FTIR), transmission electron microscopy (TEM), and differential scanning calorimetry (DSC). The particle size distribution of the emulsions was determined by Nano ZS Particle Size & Zeta Potential Analysis.The influence of emulsion polymerizing methods, the proportion of soft and hard monomers, the dosage of functional monomer, initiator and emulsifier, the reaction time and temperature, the stirring rate, etc on the properties of the emulsions and printed fabrics were investigated in detail. The prepared core-shell polyacrylic emulsion was used as the binder for pigment printing ink. The properties of the prepared binder were compared with other commercially available adhesives. The results showed that the printed fabrics using the prepared core-shell polyacrylic latex as the binder had excellent dry and wet rubbing fastness, washing fastness, soft hand feeling, and brilliant color. Most of its performances can attain the national standards.Then aqueous polyurethane was used to modify polyacrylic emulsion further. Aqueous Polyurethane - acrylic (PUA) hybrid emulsion with core-shell structure was prepared via semibatch emulsion copolymerization of butyl acrylate (BA), methyl methacrylate (MMA) and acrylic acid (AA) in the presence of a commercial polyurethane dispersion as seeds. The properties of the prepared PUA hybrid emulsions were studied by Fourier transmission infrared (FTIR), which confirmed the copolymerization of PA and PU. The microstructure of the emulsion particles, whose core and shell was composed by acrylic polymer (PA) and polyurethane (PU) respectively, was observed by transmission electron microscopy (TEM). The thermal response properties of emulsion films were measured by Differential scanning calorimetry (DSC), and the results indicated the good compatibility between PA and PU moieties in the PUA hybrids. The particle sizes and distribution of the PUA hybrid emulsion were found to vary drastically depending on the core-shell monomer ratios. Moreover, the pigment printing results showed that the pigment printed fabrics had excellent rubbing and washing fastnesses, soft hand feeling and brilliant color when the core-shell PUA hybrid emulsion was used as pigment binders.The rheological properties of the latex ink using the prepared PUA40 hybrid emulsion as the binder for aqueous pigment inks of digital inkjet printing were investigated. It was found that the latex inks exhibited viscosity plateau of Newtonian fluid behaviors, and viscous behaviors dominated in the latex and latex inks, although there was some interaction among the latex and pigment particles. The excellent flow behaviors of the PUA hybrid emulsion ensured its wide application in the areas of ink-jet printing and coating. |
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