Preparation Of Thermochromic Microcapsule And Its Application On Fabrics

Reversible thermochromic fabric is a kind of novel functional material, and it responds tochange of temperature by color change and energy conversion. This meets the individual needs offashion and innovation.In this dissertation, by changing the proportion of leuco dye, developer and solvent todetermine the optimal weight ratio of thermochromic compounds. With the method of in-situpolymerization, the reversible thermochromic compounds with excellent thermochromicproperties were microencapsulated. By coating and padding finishing, the reversiblethermochromic fabric was prepared and tested. The main results are summarized as follows:(1) For the thermochromic composite materials, the optimal mass ratio of Crystal VioletLactone (CVL) or Thermo-sensitive Red (TF-R), Bisphenol A (BPA) and1-Tetradecanol (TD)was1:3:65, the optimal weight ratio of Crystal Violet Lactone (CVL) or Thermo-sensitive Red(TF-R), Bisphenol A (BPA) and1-Hexadecanol was1:4:65. Under these conditions, thethermochromic properties of thermochromic composite materials were outstanding, and thethermochromic temperature were25.8-31.5℃,36.7-43.5℃respectively. Thermochromictemperature of thermochromic composite materials prepared by tetradecanol-hexadecanol binarymixture as solvent was between20.6℃and40.3℃.(2) The emulsifying time, emulsifying speed, reaction pH and ratio of core material and sellmaterial had great influence on the morphology, particle size distribution and thermochromicproperties of thermochromic microcapsules. So in this dissertation, the reversible thermochromaticcompounds with the optimal proportion as core materials and trimethylol melamine as shellmaterials, a series of thermochromic microcapsules were synthesized based on in-situpolymerization method, and then the technology of thermochromic microcapsule was discussed. The optimal technology parameters for thermochromic microcapsules were also concludedemulsifying speed was10000r/min, emulsifying time was10min, reaction pH value was4.0,core/shell materials ratio was3:2, reaction time was2.5h, and the dispersing agent NNO wasadded into the solution, and then the solution was treated by ultrasonic cleaner.(3) The morphology, particle size distribution, thermochromic and thermal properties ofthermochromic microcapsules were analyzed by optical microscope, SEM, DSC and colordifference machine. It can be found that these microcapsules were spherical shapes and had gooddispersion between each other; more than75%of microcapsules were obtained between4um to11um in diameter. DSC analysis showed that the phase transition temperature of thermochromicmicrocapsules was higher than the thermochromic compounds, therefore, the thermochromictemperature of thermochromic microcapsules increased to39.9-45.1℃. The thermochromicproperties illustrated that the reversible color change of thermochromic microcapsules occurredrapidly, the discoloration time was63s, and the microcapsules still had excellent thermochromicproperties after2100cycles.(4) During the finishing process, thermochromic microcapsules were used by cotton wovenfabrics, and then the thermochromic properties, wearability and mechanical properties were tested.The results showed that the thermochromic properties and thermal regulation ability were betterby the coating finishing than the padding finishing, while the air permeability and moisturepermeability were poor. After coating finishing, the thickness of fabric was0.404mm, airpermeability was203.2mm/s, moisture permeability was316.54g/(24h·m2), breaking strengthwas745.5N and elongation at break was22.13%. After padding finishing, the air permeability,moisture permeability and elongation at break were good. The air permeability was576.8mm/s,moisture permeability was426.80g/(24h·m2), thickness was0.386mm, breaking strength was725.0N and elongation at break was23.84%.