Preparation Of Photo-thermochromic Microcapsules And Its Application In Textiles

The color-changing materials can show different colors with the change of environmental conditions,which can make people intuitively discover the changes of the surrounding environment.The prepared color-changing fabric is a class of high-tech textiles with great potential.Among the many conditions that stimulate discoloration,ultraviolet light and temperature are the most common changing conditions in life.Therefore,photochromic materials and thermochromic materials have great application potential in textiles.Photochromic fabrics can protect consumers from the harmful effects of ultraviolet radiation.Thermochromic fabrics can be calibrated to reflect changes in ambient temperature,and photo-thermochromic textiles that can respond to two stimuli can meet more requirements and have more Widely used.Since the two color-changing materials respond to different stimuli and require different color-changing environments,it is necessary to provide the two color-changing materials with their own temperature-changing conditions.However,due to the influence of the surrounding environment and chemical additives,photochromic materials and thermochromic materials may undergo irreversible chemical changes,resulting in reduced fatigue resistance and even loss of color change.This has led to their microcapsule technology in the textile field.The photochromic materials and thermochromic materials are converted into micro-nano compound particles to improve their applicability,thereby preparing photo-thermal dual-response color-changing textiles.Polymethyl methacrylate photochromic microcapsules and polyurethane photochromic microcapsules were prepared separately,and their stability and color changing performance were compared.Using polymethyl methacrylate as the wall material,the photochromic material is placed inside the spiropyran polymer by the solvent evaporation method,so that the photochromic material has a stable color changing environment.When the core wall mass ratio is 2:1,the surface of the microcapsules is smooth,and the distribution is between 3 and 6μm,and the microcapsules have good color performance.When the dosage of the photochromic material continued to increase,the microcapsule surface cracked.As soon as the microcapsules are exposed to ultraviolet light,they change color immediately,and the complete color change time is 16 s.After 30 ultraviolet-visible light cycles,the photochromic microcapsules still have good color-changing properties and excellent fatigue resistance.Using SiO₂ as the wall material and CVL composite as the core material for microcapsule coating.When the ratio of cetyl alcohol is 1:3:40,it has excellent discoloration effect.By changing the type of solvent,the microcapsule discoloration temperature can be changed,and tetradecyl alcohol,cetyl alcohol,and octadecyl alcohol are used as solvents,respectively,to obtain microcapsules with a discoloration temperature of 34℃,48℃,and 57℃.The particle size of the microcapsule is about 2μm.Two kinds of microcapsules are printed on textiles at the same time to obtain photo-thermochromic textiles.Because thermochromic microcapsules are blue at room temperature,thermochromic microcapsules are colorless without ultraviolet light,so textile The initial color is blue.When the temperature rises to 36℃,the fabric gradually changes from blue to colorless.When the temperature of the fabric is unchanged and only ultraviolet light is irradiated,the fabric will eventually show the color of blue and peach superimposed.When the fabric is exposed to ultraviolet light in an environment above 36°C,the final color of the fabric is pink.When the concentration of microcapsules in printing is 4wt%,the binder concentration is14wt%,it has good reversible color performance,dry and wet rubbing fastness is 4 grades,color fastness is 4-5 grades,fade fastness Degree is 3-4.