Principles of Thermochromic Materials Microcapsules are coated with invisible dyes, couplers and temperature control agents. Color materials with different temperature intervals can be produced by selecting different temperature control factors. 2. Product description Color change principle: low temperature color development, high temperature colorless product range: -15 ° C ~ 70 ° C basic color: 15 colors can be provided for each temperature. Each color can be mixed with each other. Other color materials can be added. The colors below are close to the PANTONE color code. The color of the product depends on the actual material. Advantages of thermochromic pigments in plastic products: Thermochromic pigments are suitable for injection molding and extrusion: they are characterized by: thick wall thickness, high strength, good heat resistance, uniform dispersion, and less residual color during decolorization. Scope of application: This product can be used for injection molding and extrusion of transparent or translucent plastics, such as polyethylene (PE), polypropylene (PP), polystyrene (PS), soft polyvinyl chloride (S-PVC), AS , ABS and silica gel. . It can also be blended with unsaturated polyester, epoxy, plexiglass or nylon monomers for casting, molding and curing. Dosage: When used for injection molding, extrusion processing or casting, molding and curing, the color changing pigment is used in an amount of 0.5% to 1.0% by weight of the plastic. The color-changing pigment should be thoroughly mixed with the plastic granules (a small amount of white oil can be used when mixing). If the ordinary pigment matches the color of the color changing pigment, the ordinary pigment (or dye) is used in an amount of about 0.5 to 2.5% of the color changing pigment. Masterbatch: In large-scale production, color-changing pigments can be added to polyethylene wax or polystyrene wax to prepare a color masterbatch with a pigment content of 10%, and then mixed with plastic particles. This allows the color changing pigment to be more uniformly dispersed. Temperature: The treatment temperature should be controlled below 200 °C, not exceeding 220 °C, and the heating time of the material should be shortened as much as possible. (High temperature, long-term heating will impair the discoloration performance of the pigment). Note: After the injection molding is completed, the cold water is rapidly cooled, and the color density of the product is better. (natural cooling, slow product heat dissipation will lead to product color fading or discoloration effect) A: When using color-changing pigments in injection molding and extrusion, other fillers or common pigments (such as titanium dioxide, calcium carbonate, etc.) should not be used in plastics. Barium sulfate, carbon black, etc.), otherwise the color change effect will be shielded. B: When using color-changing pigments in casting, molding and solidification, the color-changing pigment should be added to the unsaturated polyester, plexiglass or nylon monomer to stir and disperse uniformly, and then the initiator or curing agent is added to start the Since the viscosity of the system rises sharply after the prepolymerization, the addition of the color-changing pigment at this time causes a large amount of pigment particles to be wrapped together and is difficult to disperse uniformly. Agitation operation at this time also causes a large amount of air bubbles to remain in the system. C: Careful selection of cross-linking agent or curing agent: during the cross-linking curing process of epoxy resin and unsaturated polyester resin, strong shrinkage stress Sometimes occurs inside the epoxy resin and microcapsule shell, and other chemicals enter. The interior of the pigment loses its discoloration properties. This Is often the case when the epoxy resin is cured to a thickness greater than 0.2 mm and a polyamine curing agent is used. D: Premixing of plastic particles and color changing pigments cannot be performed using a high shearing device such as a mixer, a kneader, or a high speed dispersion. Machine and twin-screw extruder. These devices can seriously damage the protective layer on the surface of the color-changing pigment, causing it to lose its discoloration properties. In addition, the color changing pigment should be prevented from undergoing repeated extrusion granulation operations in the preparation of the color masterbatch. Storage: The reversible thermochromic pigment itself is an unstable system (hard to change when it is stable), so it is much less resistant to light, heat and aging than ordinary pigments and should be used with care.
