Preparation And Study Of Organic Reversible Thermochromic Materials

The organic reversible thermochromic material is a functional material that has a color conversion function and can be recycled multiple times.The organic reversible thermochromic material system studied in recent years is often accompanied by low toxicity bisphenol A,and the organic reversible thermochromic material is greatly affected by the ambient temperature,which greatly limits the environment in which it is used and life.In this paper,bisphenol A is replaced by different kinds of chromogenic reagents,and the color-changing material is wrapped by micro-encapsulation technology,through discoloration performance,encapsulation rate,aging test,particle size analysis,scanning electron microscopy analysis(SEM),differential scanning calorimetry(DSC),infrared spectroscopy(FT-IR)and other research characterization,determined the best process for the preparation of non-toxic optimal organic reversible thermochromic material system and color-changing material microcapsules.In this paper,crystal violet lactone was selected as the coloring agent,and 1-tetradecanol was used as the solvent,and 4-dodecylphenol,isonicotinic acid,1,3-dimethylbarbituric acid and 8-hydroxyquinoline were respectively used.Four kinds of non-toxic substances were used as color developing agents to prepare a series of matching color-changing material compounds.Through the study on the color-changing effect and reversibility of the color-changing material compound,the best color developing agent was selected as 4-dodecylphenol.The best mass ratio of alkylphenol crystal violet lactone/4-dodecylphenol/1-tetradecyl alcohol system color change compound is 1:4:50,the prepared color change compound has good anti-aging performance,fatigue cycle resistance and discoloration performance,the color change temperature is between 31.6 °C and 37.1 °C,and it is bright blue at room temperature.It is colorless and transparent after discoloration,and the color reversibility is good.The preparation process was also optimized by modifying the melamine resin with anhydrous methanol,and the content of free formaldehyde in the resin was determined by acetylacetone spectrophotometry.The methyl etherified melamine resin prepared by the dry-wet process has lower viscosity and free formaldehyde content than the methyl etherified melamine resin prepared by the wet process alone.The optimum molar ratio of melamine/formaldehyde/anhydrous methanol is 1:7:15,and the percentage of free formaldehyde in the number of lipids is less than 0.3 %,which is in accordance with the standard preparation process.The organic reversible thermochromic material microcapsules were prepared by insitu polymerization method with the best quality ratio of the color-changing compound as the capsule core and the methyl etherified melamine resin as the capsule wall.The preparation scheme of the color changing material microcapsules optimized by the orthogonal test is: the addition amount of the emulsifier is 3 wt%(the percentage of the core discoloration compound),the stirring speed during the emulsification is 2000 rpm,the capsule core The mass ratio to the wall of the capsule is 0.45,and the curing pH of the microcapsules is 5.The color capsule microcapsule coating effect under the optimal preparation conditions is very good and the shape and size comparison uniform,particle size between 2.45 ?m and 2.78 ?m,and excellent color change performance and service life.