| Blue light curable digital inkjet printing of textiles integrates photo-curing with digital inkjet printing.It employs oligomers and monomers instead of polymeric binder used in conventional pigment inks to ensure a sufficient fluidity during ink-jet process,and to solve a nozzle clogging problem suffered frequently in conventional pigment ink system.After injection,the oligomers and monomers printed on the fabric surface are able to polymerize and form a tough film in situ polymerization under blue-LED irradiation,achieving the fixation of organic pigments.It has unique advantages of energy efficiency without high temperature fixation,simple process without washing and drying after-treatments,broad adaptability without selection to substrates,safety and environmental protection without risks to UV radiation and ozone releasing.However,in view of the inherent characterizatics of pigment printing,it still has the common defects of pigment printing:pigment particles are fixed on the fabric only by physical covering in the film,there are little firm forces between pigment particle and polymeric binder film.Consequently,the colorfastness of printed fabrics in blue light curable ink-jet pigment printing is difficult to achieve the high-level as reactive dye-based printing.Therefore,the construction of reactive pigment was innovatively proposed.Double bonds were introduced onto the surface of pigment particles.During photo-polymerization by blue-LED irradiation,the double bonds existed in reactive pigment particles were able to participate in the copolymerization of oligomers and monomers,the pigment particles were covalent anchoring in the polymer cross-linked network structure.In addition,a pigment-polymer integrated film can be formed,which made the color fastness of the printed fabrics significanthly improved.To achieve the aims,some works have been carried out,including the study on structure design and controllable construction of reactive pigments,the polymerization performances of blue light curable system with reactive pigments,the structure-activity relationships between surface modification state of reactive pigments and polymerization performances of inks,the printing performances of blue light curable ink.The beneficial theories and technological achievements have been obtained as guidance for the preparation of high color fastness light curable ink and the application techniques on textile ink-jet printing.The main results are as follows:1.Designing and establishing one-step structure construction method of reactive pigments.3-?Trimethoxysilyl?propyl methacrylate?KH570?was encapsulated onto the surface of the pigment,imparting active sites.The preparation conditions of the reactive pigment were optimized.The reactive conditions as follow:the water concentration was 7 mol/L,ammonia concentration was 0.15 g,KH570 concentration was 3×10-2mol/L.FT-IR showed the presence of double bonds on the surface of organic pigment,conforming the success encapsulation of KH570.Compared with original pigment,the photo-polymerization performance of blue light curable pigment ink system,the mechanical physical properties of film,and therubbing colorfastness of the printed fabric using reactive pigments were improved to certain extent.2.Designing and establishing two-step structure controlled construction method for preparation of reactive pigments.First,the encapsulation state of silica on the surface of pigment was adjusted by the amount of water and ethyl orthosilicate as well as pH,imparting the controllable grafting sites?-OH?.Then the reactive pigments of different grafting rates were controlled by the amount of KH570.Compared with one-step method,the reactive pigment was controllably prepared by two-step method with relatively smaller particle size,and the blue light curable inks had a good polymerization.The blue light cured film had better physical and mechanical properties.The rubbing colorfastness of the printed fabric using reactive pigments was improved.3.The relations between the surface modification state of pigments and the performance of blue light curable digital inks were studied.Results showed that the solvated chain length and the functional groups of the silane coupling agents determined the dispersion stability of the modified pigments in the blue-cured ink system.The double bonds or amino group on the surface of the modified pigments contributed to the polymerization performances of blue light curable ink.When double bond existed on the surface of reactive pigment with good dispersion stability and uniformity,the mechanical and physical properties of the cured film were significantly improved.The idea of the grafting modification of pigment by selecting different silane coupling agents could provide references for the development of functional pigments.4.The printing performances of blue light curable reactive pigment ink were carried out.The results show that the visocosity and polymerization performance of blue light curable inks could be effected by adding pigments to some extent.Which could be impoved by changing the temperature of nozzles and increasing the photoinitiator concentration or/and irradiation intensities,the addition of reactive pigments also could effectively reduce the effect of the pigment on the polymerization performance.Different pigments had different effects on the polymerization performances of the inks.When the ink absorbed less blue light,the ink polymerization performance was better.5.With the blue light curable pigment ink formuation?CQ/EDB=1%/1%,PUA/IBOA/HEA=60wt%/30wt%/10wt%,reactive pigment 0.52%?,lighting conditions?light intensity>16.9m W/cm2,time 5min?and pressure?20100kPa?,the ejection behavior was smooth in the simulating jet printing process,color yield of the printed fabrics was controlled by pigment amount and jet pressure.Because of the participation of double bonds of the pigment surface in the photo-polymerization,the dry and wet rubbing colorfastness of the printed fabric using 1%reactive pigment was3-4 and 4 degree respectively,which improved by 0.51 degree compared to original pigment. |
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