What is the application of thermochromic powder? What storage method is there?

The thermochromic pigment is prepared from an electron transfer type organic compound system. What is the application of the thermochromic powder? What storage method is available?

1. The thermochromic powder is a microencapsulated reversible thermochromic substance called reversible thermochromic pigment (commonly known as: temperature change pigment, temperature sensitive powder or warming powder). 2. This product can be used for injection molding and extrusion molding of transparent or translucent plastic such as polypropylene (PP), soft polyvinyl chloride (S-PVC), AS, ABS and silica gel. It can also be mixed with an unsaturated polyester, epoxy resin, plexiglass or nylon monomer to cast, mold, and cure a suitable ink substrate.

3. For injection molding, extrusion processing or casting, molding, solidification molding, the amount of color-changing pigment is 0.4~3.0% of the plastic amount, usually 0.6-2.0%. The color-changing pigment should be thoroughly mixed with the plastic particles (a small amount of white oil can be used when mixing). If the ordinary pigment is color-matched with 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.

4, color masterbatch: In mass production, the color change pigment can be first added into polyethylene wax or polystyrene wax to make a color masterbatch with a pigment content of 10%, and then mixed with plastic particles. This allows the discoloration pigment to be more uniformly dispersed. For the preparation method of color masterbatch, please refer to the technical data provided by the company.

5, temperature:

The processing temperature should be controlled below 200 °C, the maximum should not exceed 230 °C, and the heating time of the material should be minimized. (High temperature, long-term heating will impair the discoloration performance of the pigment).

  6. Note: A: When using color-changing pigments in injection molding and extrusion, other fillers or common pigments (such as titanium dioxide, calcium carbonate, barium sulfate, carbon black, etc.) should not be used in the plastic at the same time, otherwise it will be shielded. Color change effect. 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 polymerization or crosslinking reaction. 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. In addition, the 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 carried out using high shear equipment such as mixers, kneaders, high-speed dispersers, and twin-screw extruders. These devices can severely 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. E: Phosphorus-containing stabilizers and plasticizers should be avoided in the formulation of PVC resin, otherwise the color-changing injection molded products will produce severe residual color in the decolorized state.

Third, the storage method

The reversible thermochromic pigment itself is an unstable system (it is difficult to change when it is stable), so its resistance to light, heat, and aging is far less than that of ordinary pigments, and should be noted in use.

1, light resistance

Thermochromic pigments have poor lightfastness and can quickly fade under intense sunlight, so they are only suitable for indoor use. Radiation from strong sunlight and UV light should be avoided, which will help extend the life of the color-changing pigment.

    2, heat resistance

The thermochromic pigment can withstand 230 ° C high temperature (about 10 minutes) in a short time, and can be applied to injection molding and high temperature curing. However, the color-changing pigment has different thermal stability in the chromophoric state and the decolorized state, and the stability of the former is higher than that of the latter. In addition, when the temperature is higher than 80 ° C, the organic matter constituting the color changing system also starts to degrade. Therefore, color-changing pigments should avoid long-term operation at temperatures above 75 °C.