Study On The Preparation Of Liquid Crystal Microcapsules And Their Applied Performance In Textile Printing

Color-changeable fabric is a special kind of fabric which color can change with the environment (light, temperature and humidity, etc.). This type of fabric can be prepared by adding the color-changeable materials to fiber or finishing it on the fabric, and this also meets the people who demand for individuation and diversity clothing. The color-changeable fabric of crystal violet lactone has appeared, but It has many disadvantages, such as single color changing, its color is not bright enough, and low light stability, etc. These problems limit its application in the garment processing. However, the thermochromism temperature of inorganic color material is so high that it can’t be applied to the fabric.Cholesteric liquid crystal(CLC) has been widely used in many fields for its dynamic thermochromism effect, color reversibility, high color sensitivity and stability, etc. Taking advantage of this character of the CLC, people have developed many products, such as CLC thermometer, medical skin spectra and various hot color adornment. It is also applied to color cosmetics, heat transfer analysis, flow field display and nondestructive flaw detection, etc. In the process of application, CLC is susceptible to interference of external factors, so its thermochromism performance reduce greatly. In order to solve this problem, researchers protect the CLC by using microcapsule techniques, so it can be applied to textile printing freely.A kind of cholesteric liquid crystal mixture containing three cholesteryl compositions: Cholesteryl pelargonate, Cholesteryl oleyl carbonate and Cholesteryl chloride, which can successively reflect circularly polarized light from red to blue with temperature increase, was prepared by binary and ternary mixing. Finally, filtering the CLC formula which can apply to color clothes, and its color temperature range is27～32℃and sensitivity is approximately1℃. The thermochromic properties and stability of the liquid crystal system is studied.This paper synthesized a kind of emulsifier which is applicable to liquid crystal microcapsules, and some of its features were characterized by IR. The HLB value of the emulsifier is28.45, so it has a good performance for hydrophilicity. Then apply it to the process of the CLC microcapsule. The process for microencapsulation based on complex coacervation of gelatin-acacia and as been investigated. Different factors affecting the microcapsule preparation were studied, and the results that the optimized method is:emulsification rate2000rpm, emulsification time20min, emulsifier content2wt%, microcapsules temperature50℃, pH valuo4.5. At last, the appearance and grain size of the microcapsules were characterized by scanning electron microscope, optical microscope and laser particle size instrument. The results show that the CLC microcapsules were very spherical with smooth surfaces, and its particle size is about15microns. They were applied to the fabric printing and produce the color clothing which has obvious thermochromism effect.