Study On The Application Of Reversible Thermochromic Dyes In Textile Printing

Reversible thermochromic dyes are a kind of dyes, compounds or mixture, whose visible absorption spectrum changing with the temperature variation. Their color will change with the temperature changes. Because of this performance, they were widely used in medical healthcare and textile, anti-counterfeiting mark other fields. In addition, because of their characteristics of simple manufacturing, convenient and quick-identification and low-cost, the application of organic reversible thermochromic dyes has a lot of advantages, and develops rapidly.In this article, reversible thermochromic dyes were prepared with crystal violet lactone as electron donating compound, biphenyl as the electron accepting compound and cetyl alcohol as solvent. By changing the ratio of raw materials and testing the time and temperature of color changing of the resulting thermochromic dyes, the optimum ratio of the synthesis was obtained finally. It was crystal violet lactone: biphenyl: cetyl alcohol= 1: 3: 50. By means of thermal analysis of thermochromic dyes, the temperature range of color changing was obtained, was 42.5 degree celsius to 45 degree celsius. By way of infrared analysis of crystal violet lactone and thermochromic dyes, and contrasting their infrared spectrogram, the structure of thermochromic dyes was confirmed, and the mechanism of color changing was obtained, was electron transfer mechanism.The thermochromic dyes microcapsules were obtained by in-situ polymerization. By the analysis of scanning electron microcope and particle size analyzer, it was found that microcapsules had good morphology and uniform size distribution, and their average size was 9μm. Through the processing of a variety of solvent and acid and alkali and thermalgravimetric analysis, it is concluded that the microcapsules had good acid and alkali resistance, solvent resistance and thermal stability. In addition, by contrasting the K/S cruve and chroma value of before and after color changing of printing fabrics, it was found that the fabrics had good thermochromic effect, the time of color changing was 59 s, and the temperature range was 43.5 degree celsius to 44.5 degree celsius.The optimum condition of printing–drying-baking process of thermochromic dyes microcapsules printing on silk fabric was obtained. By using thickener PDC and binder Superprint 101-APF, the optimum condition was that thickener dosage 2%, binder dosage 10%, adjusting the p H to 8-9, dry at 60 degree celsius after printing, then baking for 2min at 140 degree celsius. Then, the different dyes were mixed and applied, by contrasting the color and K/S cruve and chroma value of the resulting printing fabrics at different temperatures, it was found that the fabrics had good thermochromic effect.The styles and the rubbing fastness and the washing fastness of thermochromic-dyes printing fabric in optimum condition and silk fabric were tested. It is concluded that the thermochromic dyes printing fabric’s softness and elasticity and drape decreased slightly. However, it had high tensile deformation resistance and smooth texture. The printing fabric also had good rubbing fastness and washing fastness grade.