| Textile inkjet printing is in a period of rapid development and a very creative technology,which is able to produce with excellent color expressive force,high resolution and differentiated high-quality printed fabrics,also meets the individual,small batch,fast delivery of the market demand.The surface feature of the fabric is an important factor in determining the color performance and pattern clarity of the inkjet printing.Fabric modification processing is the first process of inkjet printing,which can re-build the fabric surface structure and properties,and is the key process to determine the quality of inkjet printing.The research on the mechanism of fabric modification and its influence on the effect of inkjet printing is helpful to accelerate inkjet printing technology for industrial production applications.The research contents of this subject include two main parts:The polymer modification of cotton fabric and its effects on the color properties of inkjet printing were studied for reactive dye and pigment inkjet printing,respectively.Firstly,the polymer modified cotton fabrics were prepared by coating with a semi-auto flat screen?printing small prototype and the padding-drying method.And then the monochrome blocks with a different color fill rate were printed on these fabrics.The color data of the printed fabrics was measured using a colorimeter.The surface structure of the fabric before and after modification was characterized by a scanning electron microscopy.The contact angles of the probe liquids on the surface of the fabric were measured by the contact angle meter,and the surface free energy of the fabrics was calculated according to the OWRK method,combined with the surface tension of the probe liquids.The shape and distribution of ink dots on the fabric were observed with an optical microscope.The spreading of different volumes of droplets on fabrics,yarns and fibers were tested.Based on the experimental results,it was revealed that the reason and mechanism of the improving effect of cotton fabric polymer modification on the color performance of inkjet printing.The main results are as follows:(1)Compared with the sodium alginate modified fabric,the K/S value of the reactive dye inkjet printed fabric,which was treated with sodium alginate plus higher fatty acid derivative(PT),was increased by more than 11%.While the color saturation C*increased].9?2.5;and the pattern definition and overall sense of hierarchy was significantly improved.(2)When compared with the untreated fabric,the contact angles of redistilled water and diiodomethane on the fabrics pretreated with sodium alginate and sodium alginate plus PT were improved gradually,due to the difference of the distribution of modifier on the fiber surface.The free surface energy of the two pretreated fabrics was decreased by 4.34 mJ/m2 and 15.3 mJ/m2 respectively,while the dispersions component gradually decreased,and the polar component increased first and then decreased.The hydrophobicity of the fabric after modification increased.(3)When printing a monochrome block with a color fill rate of 20%on the fabric,it was possible to obtain independent dots.As the spreading speed of the ink droplets along the fiber length direction and the diameter was different,the shape of the ink dots was long strip on the inkjet printed fabric.The hydrophobic of the fabric treated with sodium alginate plus PT was increased,this could be helpful to control the spreading of ink droplets and the size of ink dots,it can significantly improve the pattern definition,vividness and overall color performance.(4)The layer of sodium alginate film was formed on the surface of the fiber of the sodium alginate modified fabric by coating once with a semi-auto flat screen-printing small prototype.Urea crystals were formed on the surface of the fiber modified by coating 2 times and 3 times,due to the gradually outward migration of urea in the modification solution,with the evaporation of water in the drying process.The gap between the fibers and the yarns was substantially filled.(5)The penetration ratio of the cyan reactive dye into the inside of the fabric was 77.9%,51.1%and 37.5%respectively,which was modified by coating one,two and three times.The fabrics were inkjet printed with a monochrome block with a color fill rate of 50%,and steamed with saturated steam at 102 ? for 14 min.Dye distribution on the fabric surface helped to improve the color performance of inkjet printing.(6)The amount of modifier applied to the fabric was an important factor affecting the fixation rate,lack of modifier and excess,could reduce the fixation rate.Compared with the fabrics modified by coating 1 time and three times,the fixation rate of cyan reactive dye was the highest on the fabric modified by coating 2 times.The fabrics were inkjet printed with a monochrome block with a color coverage of 50%,and steamed at the same condition.(7)Compared to the unmodified fabrics,the modification of cotton fabric with cationic polymer could significantly improve the color depth and color saturation for pigment inkjet printing.At the maximum absorption wavelength,the K/S value of the cyan inkjet printing fabric was increased by 31.2%,and the increase rate of magenta,yellow and black was 65.2%,32.3%and 46.5%respectively.The C*values of cyan,magenta and yellow ink jet prints were increased by 2.5,6.1 and 6.9,respectively.(8)The Zeta potential test results showed that the pigment particles in the ink were negatively charged with a potential between-31.6 mV and-41.]mV.The cationic polymer emulsion was positively charged with a potential of 26.7 mV.The modification of cotton fabric with the cationic polymer could effectively inhibit the spread of ink droplets on the fabric for pigment inkjet printing.(9)On the unmodified fabric,the spreading area of cyan,magenta,yellow and black ink droplets,with a volume of 4.0 ?L,were 89.2 mm2,114.3 mm2,109.1 mm2 and 127.6 mm2 respectively.Compared with the unmodified fabric,the spreading area of cyan,magenta,yellow and black ink droplets on the cationic polymer modified fabric decreased by 47.2%,50.0%.58%and 57.4%,respectively.The research revaled the effect of the modification of cotton fabric with cation polymer on the spreading of ink droplets during inkjet printing process,it proved the law between the color performance of inkjet printing and the spreading of ink droplets,the color effect of inkjet printing was negatively correlated with the spreading of ink droplets,summarized fabric modification technology of controlling the spread of reactive dye and pigment ink droplets,to provide basic theoretical guidance of the actual production of textile inkjet printing. |
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