The anti-blocking masterbatch is used to prevent the films on the coil from adhering to each other. Due to the effect of temperature and time, adhesion occurs when two thin films are pressed together. After adding the anti-blocking masterbatch, not only the adhesion is reduced, but also many properties of the film are improved.
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1. The application formula of the anti-blocking masterbatch in the casting film
The effect of anti-blocking masterbatch is usually indicated by bond strength, and most companies have their test methods, but the ASTM standards D1893 and D3354 also describe the anti-blocking masterbatch test.
2. Silicic addictive has the following characteristics:
（1）Amorphous
It is amorphous (that is, an amorphous lens), so it does not cause silicosis.
（2） High refractive index requirement
Transparent film because of its high purity, and refractive index is especially important, and the requirements are almost the same as PP.
（3）Softy
It won’t wear out the screws of the extruder because it’s soft.
（4）Evenly dispersed
Because of the compact arrangement of the chain segment structure, it is evenly dispersed in the film.
Compared with natural silica, the concentration of the anti-blocking masterbatch used in the film can be greatly reduced.
（5）Thinner film adds more
According to the experience of functional masterbatch manufacturers, the particle size used in BOPP silica in this field is usually between 2 and 4μm.
The amount of effective anti-stick depends on the thickness of the film and is generally 200-1000PPM (Between 0.2-0.1%), the thinner the film, the more anti-blocking masterbatch.
Since the anti-blocking masterbatch is an inorganic product, it does not migrate and will be effective after film production.
3. The influence of the anti-blocking masterbatch on the film and matters needing attention
After adding the anti-blocking masterbatch, not only the adhesive strength of the film is reduced, but also many properties of the film are improved. However, the addition of the anti-blocking masterbatch should also be limited due to the degradation of the optical properties of the film.
Based on the experience of functional masterbatch manufacturers, it is best to choose a high purity of the anti-blocking masterbatch, to minimize the amount of the anti-blocking masterbatch, and to avoid the addition of too much influence on the transparency of the film.
Note:
Waterproof steam packaging must be stored in a dry area because of the high hygroscopicity of the anti-blocking masterbatch.
Before use, the water content of the anti-blocking masterbatch must be tested by increasing its weight. If the water content is too high, spots and bubbles will form in the film.
