Preparation process of BOPP film
DATE：2020/9/17 8:51:42 / READ： / SOURCE：This station
Preparation process of BOPP film
(1) Extrusion. PP enters the extruder, after a certain temperature and time, under the action of the rotating shear force of the screw, the pellets enter the filter quantitatively after melting and metering. The extrusion temperature can be adjusted at 230℃～280℃, but under the premise that the material can be plasticized uniformly, the temperature control should be lower, and the material degradation should be avoided as far as possible due to excessive temperature and excessive heating time. www.handern.com Non-woven equipment(2) Filter. PP fresh materials, side materials, recycled materials, recycled materials, recycled materials, etc. all contain impure impurities and infusible materials. These infusibles must be filtered out with a filter, and can not enter the die and mix with thick pieces. The filter screen should be selected properly. Although the mesh number is too high and the mesh is too fine, although it is good for the extrusion of thick sheets, it will increase the frequency of filter replacement and increase the consumption of raw materials; if the mesh is too large, impurities are not filtered cleanly and mixed into the thick sheet. It will cause membrane rupture by horizontal pulling. Generally, the mesh number should be slightly higher, and the filter should be replaced every 7d-10d. www.handern.com Non-woven equipment
(3) Die casting piece. After the material is filtered, it enters the die. The die is divided into two types: flat film T-shaped and tube film round. To produce different products, it is necessary to use a single-layer die or a multi-layer co-extrusion die, and adjust the distribution through the "black box" material channel above the die, so that different materials flow out of the lip according to different layered channels. Thick sheets can be divided into different layers as required. Through the "black box" and
The change of die head can produce single-layer, two-layer, three-layer, five-layer and seven-layer co-extruded composite thick sheets. The die head and lip can be adjusted manually or automatically according to the thickness distribution feedback information of the thick sheet and the product, so as to make a uniform thick sheet. www.handern.com Non-woven equipment
(4) Rapid cold forming. Isotactic PP is a crystalline polymer with a maximum crystallization temperature of 90°C. The molten material is extruded from the lip and flows through a gap of several millimeters to the surface of the rotating quenching forming roll, where it is compressed air knife, quenching forming roll cold surface, water bath ( Under the common cooling of air), the material up to 250℃ is quenched to room temperature, forming a thick amorphous sheet with very small crystallites and almost transparent. Thick slices
The quality of the film is the key to film formation. The film breaking phenomenon often occurs in the horizontal stretching process, and the main reason for the film breaking is the poor quality of the thick film. The ideal thick film should have the characteristics of flat surface, uniform thickness and straight edges, no bubbles, no impurities and "fish eyes", and almost transparent. www.handern.com The thick sheet with good non-woven equipment has strong adaptability to the stretching process, high film formation rate and good product quality. www.handern.com Non-woven equipment Whether it is a large roll water bath rapid cooling or a multi-roll alternating cooling process, it is to obtain a good thick sheet to ensure smooth longitudinal and transverse stretching. www.handern.com Non-woven equipment
(5) Thick film thickness measurement. The thickness tolerance of the film is an important technical index, and the thickness tolerance of the thick sheet plays a decisive role in the thickness tolerance of the film. www.handern.com Non-woven equipment
Author：admin