Preparation And Printing Application Of Polyurethane-CVL Thermochiomatic Microcapsule Material

The reversible thermochromatic textile has advantages of easy to identify, dynamic color, difficulty to imitation. The reversible thermochromatic cotton textile was prepared by reversible thermochromatic microcapsule. The reversible thermochromatic microcapsule with color change temperature close to 40℃ was prepared by in-situ polymerization, and the shear emulsification process was optimized to improve microcapsule properties. The cotton textile was contacted to the reversible thermochromatic by screen printing and its properties were expressed.The reversible thermochromatic material is a function material which can change its color when the environment temperature reaches a certain temperature. Researchers abroad are having a long research on the structure, color change mechanism and affecting conditions of the reversible thermochromatic material. CVL has a widespread application on color indication, carbonless paper, laser recorder because it has properties of fast color-change, small amount of sublimation and good oil soluble. Polyurethane has a application on fields of fiber, insulation material, synthetic leather, waterproof material, adhesives, paper and paving material, especially the biological material. Polyurethane has a micro-phase separation structure and properties of excellent flexibility, abrasion resistance, impact resistance and tensile. The in-situ polymerization is having polycondensation on the surface of the capsule core material under a certain condition through the initial polycondensate oligomers provided by monomer or monomers and the catalyst. It’s a method to prepare microcapsule. In this paper, polyurethane is wall material. We have a research on the typical process conditions and discuss the effect of core material ratio, the reaction temperature, stirring speed, emulsifier content and PH value about preparing the reversible thermochromatic microcapsule. Last, we provide guidance for the preparing the reversible thermochromatic microcapsule and develop a thermochromic textile material.The optimized emulsification process of the in-situ polymerization is as followed:stirring speed 1500r/min, stirring time 60min, emulsifier content 2%. The preparing reversible thermochromatic microcapsule have a uniform diameter, obvious color effect and provide a foundation for screen printing. The reversible thermochromatic cotton textile, after washing, is just having a slightly lower in color value,4 in washing fastness and it meet the wearability. The dry rubbing fastness and wet rubbing fastness of the reversible thermochromatic fabric both reach 4. The reversible thermochromatic fabric have a good hand feel and so it can be widely used in printing fabrics. Printed fabric can change color from color to colorless to color under condition 20℃-45℃ in 4s-45s.The dispersion conditions of reversible thermochromatic microcapsule printing paste follow as:PVA 10g, water 90ml, heat to 90℃, stir to dissolve to form a uniform solution.37% formaldehyde 46ml, PH value 4, after completion of reaction, add 13g urea, to remove the excess of formaldehyde, to obtain the modified PVA solution. Adding filler, grind 50min, to prepare a coating semi. Add silica sol to modify and improve coating properties, and then add reversible thermochromic powder to obtain a reversible thermochromic printing paint. With the increase of the mass fraction of the printing paste, printing cotton fabric color value gradually increased, but after washing the color value printed cotton fabric reach a certain value and began to decline. The optimum printing paste is printing paste optimal mass fraction 10%, roasted baking temperature 120℃, baking time 4min, considering color value, integrated optimization fabric color value before and after washing, rubbing fastness and other factors of the printed cotton fabric.