热致变色材料
原理
微胶囊涂有隐形染料，成色剂和温度控制剂。通过选择不同的温度控制因子，可以生产具有不同温度间隔的颜色材料。
2.产品描述
变色原理：低温显色，高温无色
产品范围：-15°C~70°C
基本颜色：每种温度可以提供15种颜色。每种颜色可以相互混合。可以添加其他颜色材料。以下颜色接近PANTONE颜色代码。产品的颜色取决于实际材料。
热变色颜料在塑料制品中的优点：
热致变色颜料适用于注塑和挤出：
Its characteristics are: thick wall of the capsule, high strength, good heat resistance, easier to disperse evenly, and less residual color during decolorization.
Scope of application:
This product can be used for injection molding and extrusion molding 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 mixed with unsaturated polyester, epoxy resin, plexiglass or nylon monomer 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 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.
Color masterbatch:
In mass 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 discoloration pigment to be more uniformly dispersed.
temperature:
The processing temperature should be controlled below 200 °C, not more than 220 °C, and minimize the heating time of the material. (High temperature, long-term heating will impair the discoloration performance of the pigment).
Precautions:
After the injection molding is finished, the cold water is rapidly cooled, and the color density of the product is better. (natural cooling, slow heat dissipation of the product will lead to product color fading or discoloration effect deterioration)
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 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 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：塑料颗粒和变色颜料的预混合不能使用高剪切设备如混合器，捏合机，高速分散机和双螺杆挤出机进行。这些装置会严重损坏变色颜料表面的保护层，使其失去变色性能。另外，应该防止变色颜料在制备色母料时经历反复挤出造粒操作。
存储方式：
可逆热致变色颜料本身是一种不稳定的体系（当它稳定时很难改变），因此它对光，热和老化的耐受性远低于普通颜料，应在使用中注意。
