Guangdong Huaping Hygiene Material Industrial Co.,Ltd. main products include PE cast film,breathable membrane,PE perforated film,Multicolor printed film,Nonwoven Laminated film,Anti-counterfeiting Holographic film etc .
The manufacture of microporous breathable membranes can be divided into blown film method and cast method according to different film making processes; according to different stretching processes, it can be divided into unidirectional stretching method, bidirectional stretching method and partial stretching method. Compared with ordinary PE cast embossed film, the manufacture of breathable film has higher technical requirements. During the production process, special attention should be paid to the following aspects:
1) Selection of raw materials
Resin selection
Rigid breathable film – high density polyethylene; flexible breathable film – low density polyethylene; high tensile breathable film – high strength polyethylene; printing (color registration, positioning and cutting) – high strength polyethylene
Choice of Calcium Carbonate
Surface treatment of calcium carbonate: fluidity, extrusion stability, die coking, pinholes, film mechanical properties, etc.
Selection of calcium carbonate particle size: tensile properties, moisture permeability, uniformity, processability
The choice of raw materials directly affects the processability of the breathable film (such as coking time, extrusion stability, manufacturability of thin film materials and pinhole defects, etc.) and physical properties (such as air permeability, water pressure resistance, thermal stability and mechanical properties. wait). Therefore, the first thing to consider when choosing a breathable material is to meet the customer’s physical requirements for the film and the matching status with the processing equipment;
2) Dehumidification system
The high humidity of the raw material is the main cause of holes in the breathable membrane and coking of the T-film, which will seriously affect the production efficiency and product quality of the breathable membrane. Therefore, the production of breathable membranes not only requires dehumidification of raw materials (<250ppm), but="" also="" strict="" humidity="" control="" requirements="" for="" raw="" material="" transportation="" and="" flash="" recovery="" systems="">
3) Extrusion thickness control
Stretching can amplify the deviation of extrusion thickness, so the control of extrusion thickness is the premise to ensure the uniformity of final product thickness;
4) Stretch control
There are two necessary conditions for the manufacture of breathable membranes, one is calcium carbonate, and the other is stretching. Therefore, stretching is critical in the manufacture of breathable membranes. Stretching temperature, stretching ratio, stretching rate and stretching gap are the four elements of the stretching process. Its overall balance will have a great impact on the air permeability, mechanical properties, consistency and appearance of the breathable film;
5) Heat treatment
Recovering and relaxing the rigid polymer chain segment after stretching by heat treatment is a necessary means to improve the stability of the breathable membrane material in the subsequent process and during use.
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