Stretched film crystal dots are usually composed of machinery, processing technology, materials, and the like. However, the mechanism of the crystal point of the polymer is due to the occurrence of the polymer, so that as long as the possibility of the occurrence of the polymer, the crystal point may be caused.

1. The effect of the stretched film material, the influence of the material refers to the residual catalyst effect of the material.

When the polymer is produced, there will be some catalyst residues. During the molding process, the polymer melt containing the catalyst sticks to the appearance of the production equipment. At high temperature, the residual catalyst continues to catalytically polymerize the polymer, thus forming an excessive polymerization. Things.

Different stretching equipment manufacturers have different polymerization equipments and processes, and the purity of the residual catalyst treatment is different, which has different effects on the crystal point of the polymer in the film formation of the stretched film, for example, the residual catalyst content in the polymer is low. The structure of the equipment is good, and the material itself contains less crystal points.

2. The effect of oxygen in the polymer is mainly because when the processing temperature is high, oxygen will cause the polymer to oxidize and generate free radical adsorption on the wall of the die, and the free radical acts as an active center to initiate the reaction of other polymer molecular chains, which constitutes high here. The unstable polymer at a concentration becomes a motley point at high temperatures.

Participate in a certain amount of antioxidants, which has the effect of preventing the crystal point of the stretched film from occurring.
3. The influence of the processing technology and processing equipment of the stretch film, the processing technology is mainly the influence of temperature control, and the long-term heating, excessive polymerization and degradation of the stretched film material will cause the crystal point to occur.
In fact, many times it is caused by equipment, for example:
1) The die-cutting part of the film blowing machine is poorly planned and has a dead angle, which constitutes a long-term heating, excessive polymerization and degradation of a few materials; 2) the aspect ratio configuration of the stretch film blowing machine, poor die planning, etc.; 3) Some carbonization occurs on the top of the screw or on the inner wall of the barrel due to long-term accumulation, and these carbonized things can act as gel points, constantly adsorbing more impurities onto it, and continuously squeezing onto the stretched film. It constitutes a so-called crystal point.
In summary, regular cleaning of the stretch film forming equipment is beneficial to reduce the occurrence of crystal points.
4. Effects of pigments, masterbatches, etc.
Nowadays, the masterbatch of the stretched film usually increases the masterbatch. The poor dispersion of the masterbatch leads to poor defects such as crystal point. For example, the pigment selected in the masterbatch is unstable in appearance treatment, and “gather” during the processing of the masterbatch. It constitutes "powder point"; the carrier resin of the color masterbatch is not compatible with the film-forming material.
Ways to reduce or eliminate the stretched film crystal point
Knowing the reasons for the above crystal points can be easily manipulated. Qianghui Technology lists the following four methods:
1. Select the purified resin from the stretched film material to reduce the influence of the catalyst;
2. Increase the fineness of the filter in the stretch film forming process, and change the filter screen (especially the old-fashion equipment) to facilitate the reduction of the crystal point;
3. Appropriate increase in antioxidants during the production process;
4. Add steel surface lubricant during the production process of the stretched film to reduce the viscosity of the polymer melt on the exterior of the equipment.