The raw material of talc powder is talc. The talc has the advantages of high gloss, small oil absorption and good transparency. Good chemical stability and excellent physical properties are favored by the majority of modified manufacturers. Its density is 2.7 ~ 2.8g / cm3 , similar to heavy calcium, Mohs hardness is 1, the hardness is the lowest in inorganic powder, in the preparation of talcum powder because it is relatively soft, only need simple mechanical friction, However, if a better surface activation modification effect is to be achieved, a special process is required.
1
How to measure the quality of talcum powder?
(1) Purity
The higher the purity of talc, the better the enhancement. Other mineral impurities and metal minerals (especially iron) in talc have a significant effect on the aging resistance of plastics.
(2) Wet whiteness and hue
The color of the plastic changes more or less after the talc and plastic are mixed. Dark plastic products do not have too high a requirement for added talc whiteness. However, in order to make the light color product have a better color, the talc should have a higher wet whiteness and a suitable hue.
(3) SiO2 content
The content of silicon (SiO2) in talc is an important indicator for measuring the grade of talc. The talcum powder should be selected according to the performance requirements of different plastic products. For example, the talc powder added to the film should have a higher silicon content, a smaller particle size and a narrow particle size distribution, so that the film has high light transmittance, tensile strength and puncture resistance. Significant improvement in indicators such as sex. In the injection molding, sheet and bar, the silicon content is not necessarily too high, and the talc powder with lower silicon content is lower in price and rich in resources.
(4) Liquidity
In the extrusion process, the talc is less fluid than other granular inorganic materials, the dispersion is difficult, and the screw torque is large, so the use of a good activation aid is the key to overcome the above problems.
(5) Static electricity
The talc has a layered structure, large specific surface area, irregular shape of the particle shape and convex and concave shape of the surface, which makes the friction coefficient large, and it is easy to generate static electricity, which causes aggregation between the fine particles, which is difficult to disperse and affects the application effect.
2
Application of talc in modified plastics
Talc powder can be widely used in PP, PE, PS, PA, ABS, PC, PVC and other resins. While reducing the production cost of plastic products, talc has the advantages of significantly improving the rigidity, heat resistance, creep resistance and shrinkage of plastic products.
(1) Film products
Talc can also improve the mechanical properties of the film, such as tensile strength, flexural strength and rigidity. It also makes the appearance of the film more colorful, pearly, and improved in hand.
(2) Wire drawing products
The fine talc powder can obviously improve the physical properties of the woven bag, and the service life and long-term safety of the product are obviously improved. Satisfactory results can be obtained by adding an appropriate amount of talc to enhance the modified masterbatch in the production of round filament products. For example, adding 5% to 10% of the product in the fishnet wire can effectively reduce the entanglement resistance of the fishing net wire, improve the visual effect of the fishing net in the fishing operation and improve the fishing efficiency without affecting the transparent effect of the fishing net.
(3) Hollow products Â
The plastic barrels in hollow products are new type of packaging containers, which have the advantages of chemical stability, low corrosivity, light weight, clean and hygienic, low production cost, etc. They can replace barrels made of metal materials and are widely used in chemical industry. Liquid packaging for use, grease, food supplies, medical supplies
(4) Injection products
There are many types of injection molding products, mainly industrial parts, toys, and daily necessities. The application of talc powder in injection molding products can significantly improve the mechanical properties of injection molded products, reduce the depression caused by shrinkage of gates and edges of injection molded parts, and improve the transparency, appearance and hand feeling of products. Talc also has excellent dielectric properties and barrier properties, reducing the effects of magnetoelectric radiation.
(5) Auto parts and aviation, military components
Talc powder is the earliest application in automotive plastic parts and the largest amount. In the industries of aircraft, aviation, aerospace, military and other industries, the chemical resistance, high and low temperature stability and excellent mechanical properties of talc have been recognized and widely used. Military ammunition packaging boxes, medicine boxes, mechanical decorative parts, etc.
(6) Home appliance parts
In recent years, China's home appliance industry has developed rapidly. According to relevant information, 60%-80% of home appliances are made of plastic parts. Talc not only reduces the production cost of home appliance parts, but also improves the quality and appearance of home appliances.
(7) Pipe and sheet products
Talc powder can improve the bursting pressure of the pipe, especially the ring stiffness is an important index restricting the large plastic pipe. After adding a certain amount of talcum powder, the ring stiffness of the plastic pipe can be obviously improved, the dimensional stability of the product can be improved, and the plate can be improved. Stiffness, flame retardancy and chemical stability.
(Article source: plastic ring)
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