Synthesis And Modification Of Sulfonated Waterborne Polyurethane For Application In Water-based Ink

With the gradual increase in awareness of environmental protection and the improvement of various related laws and regulations, the pollution and emission problems caused by solvent-based polyurethane becoming more seriously for containing volatile organic solvents, the solvent-based polyurethane is limited recently. Waterborne polyurethane(WPU) which uses water as the dispersing agent shows series of desirable features, such as non-toxic, non-pollution and low volatile organic compounds(VOCs). Therefore, WPU is gradually used to replace the solvent-based polyurethane in leather finishing agents, adhesive, coatings and other fields. In this thesis, the synthesis and modification of sulfonated waterborne was studied, and then the resulted emulsion was applied in the water-based ink.Sulfonated waterborne polyurethane(SWPU) emulsion was synthesized by using isophorone diisocyanate(IPDI) and poly-caprolactone diol(PCL) as main raw material, ethylenediamine sodium sulphonate(AAS) as hydrophilic group, and ethylene diamine(EDA) as chain extenders through pre-polymer method. The effect of AAS content, R value and BDO/PCL(mass ratio) on properties of SWPU was deeply investigated. In addition, synthetic process was optimized to obtain the optimal synthetic route. When AAS dosage was 3%, R value was 1.6~1.8 and BDO/PCL was 0.4, the SWPU emulsion had good particle distribution and the film had excellent properties. The investigation of synthetic process showed that the process was controllable and excellent emulsion was acquired when the ethylenediamine was feed after water with the condition of pre-polymerization temperature 80 ℃ and dispersing speed 2000 rpm.The sulfonated waterborne polyurethane was synthesized and modified by castor oil(C.O). The influence of the content of C.O on the properties of SWPU emulsion and film was characterized by FT-IR, particle size test, water absorption test, mechanical properties test and thermal gravimetric analysis etc. The results indicated that, the emulsion particle size increased gradually with the increase of the amount of C.O. The introduction of C.O was beneficial to improve the mechanical properties and heat resistance of film; and the resistance to water of the film was obviously enhanced. However, when the C.O amount is too lager, intermolecular crosslink density is too large to lead to failure of the emulsifying. The most optimal mass ratio of C.O and PCL was 0.5. The tensile strength of the film was 15.15 MPa, the elongation at break was 1192.65%, and the film had better water resistance, the maximum contact angle was 95.18°.Soybean oil(ESO)-based polyols was synthesized from epoxidized soybean oil(ESO) and 2-Ethyl hexanol(isooctanol) via a ring-opening addition process, and then was used to modify sulfonated waterborne polyurethane. Fist polyols was confirmed by FT-IR and 1H-NMR; then the effect of polyols contents on the stability of emulsion and the properties of film was analyzed through particle test, mechanical property test, water absorption test and static contact angle test etc. The results showed that with the increase of content of polyols, waterborne polyurethane emulsion particle size increased gradually; water absorption rate of the films decreased, and the tensile strength increased, but elongation at break decreased. When the amount of adding polyols was too large, it leaded to failure of the emulsifying. When the mass ratio of polyols to PCL was 0.2, the water absorption of the films decreased from 50.14% to 12.27%, the water contact angle was 103.3°, and the tensile strength increased from 8.16 MPa to 21.77 MPa. Additionally, the incorporation of polyols would bring improvement of heat resistance.The water-based ink was prepared by using the homemade sulfonated waterborne polyurethane as base material, pigments and stuffing. The optimized formula of water-based ink was obtained by investigating the dispersants contents and P/B ratio. Then, three kinds of water-based ink were prepared by homemade sulfonated waterborne polyurethane. The general performance tests showed that the inks modified by the castor oil and polyols exhibited better performance, such as the improvement of the performance of adhesion and water resistance. Above all the water-based ink would show broad application prospects in the future.