Introducing the temperature change powder application

I. Principle and structure of color change of thermochromic pigments: Thermochromic pigments are prepared by electron transfer organic compound systems. Electron-transfer organic compounds are a class of organic chromonic systems with a special chemical structure. The temperature-sensitive powder changes the molecular structure of the organic substance by electron transfer at a specific temperature, thereby realizing color conversion. The warm powder color-changing substance is not only bright in color, but also can change the color from the "colored = colorless" state, which is not possessed by the heavy metal complex salt complex type and the liquid crystal type reversible thermochromic substance. The microencapsulated reversible thermochromic substance is called a reversible thermochromic pigment (commonly known as: warming pigment, temperature sensitive powder or warming powder). The pigment particles are spherical in shape and have an average diameter of 2 to 7 microns (one micron is one thousandth of a millimeter). The inside is a color-changing substance, and the outside is a transparent shell with a thickness of about 0.2 to 0.5 μm that neither dissolves nor melts. It protects the discolored material from other chemicals. Therefore, it is important to avoid damaging this layer of the casing during use. The temperature-sensitive powder can be repeatedly changed in color as the temperature rises and falls. (In the case of red at 31 ° C, the color change form is colorless above 31 ° C and red under 31 ° C). The temperature-sensitive powder contains microcapsule color-changing particles with an average diameter of 2 to 7 microns, and has the characteristics of high temperature resistance and oxidation resistance. The design of temperature-sensitive color-changing products is based on the color change in high-temperature environment and low-temperature environment, and is mostly applied to human body temperature-sensing products, and can also be used for anti-counterfeiting design.

Second, temperature sensitive color powder application:

1. The temperature change powder can be used for injection molding and extrusion molding of PE, PP, ABS, PS, PVC, PU, TPU, TPR, EVA and other plastic materials. It can also be mixed with an unsaturated polyester, epoxy resin, plexiglass or nylon monomer to cast, mold, and cure a suitable ink substrate.

2. When used for injection molding, extrusion processing or casting, molding, and 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 thermochromic pigment, the amount of the ordinary pigment (or dye) is about 0.5-2.5% of the color-changing pigment.

Third, the storage method: Reversible thermochromic pigment itself is an unstable system (stable is difficult to change), so its resistance to light, heat, aging and other properties far less than ordinary pigments, should be noted in the use.

1. Lightfastness: Thermochromic pigments have poor lightfastness and will fade quickly after exposure to strong 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: Thermochromic pigment can withstand 230 ° C high temperature (about 10 minutes) in a short time, can be applied to injection molding and high temperature curing. However, the thermochromic 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, thermochromic pigments should avoid long-term operation at temperatures above 75 °C.