The puncture resistance, also called puncture resistance, is a very important physical property index of the composite film. It reflects the maximum resistance of the composite film when the composite film is subjected to the force from the inside or the outside of the sharp object. The processing and use of ordinary composite membranes is often not very concerned about this indicator, but for some special-purpose composite membranes, this indicator is very important. Ignoring this, it is easy to cause mass quality accidents and bring serious losses.
The following is a brief discussion of the factors affecting the puncture strength of composite membranes.
1, material selection
The factor to be considered in selecting materials is to determine the material structure, for example, to increase the puncture resistance, whether to increase the nylon layer, whether the surface layer is PET film structure or PA film structure. In comparison, nylon is used. The composite film of the layer will have a significant improvement in puncture resistance. In the case where the material structure of the composite membrane has been determined, it is necessary to determine the thickness of each material. Under the same conditions, the thicker the material thickness, the greater the puncture strength of the composite membrane; the selection of the composite glue and the determination of the coating amount, due to the glue Different characteristics, after complete curing, some glue will make the composite film hard, and some make the composite film softer, the composite film of the same material and thickness, soft and hard, the puncture strength is obviously different.
2. The effect of single layer membrane on puncture strength
The puncture strength of the composite film is directly related to each single layer film. The puncture strength of the composite film can play a decisive role for each single layer film. The strength of all single layer films must meet the standard requirements. The puncture strength of the composite membrane is not a simple superposition of the puncture strength of the monolayer membrane. There are complex mechanical factors, such as 8.5~12.0N for single layer BOPA15u and 16.0~19.0N for BOPA25u, but BOPA15u//BOPA25u for composite membrane structure. //The anti-piercing strength of AL7u//PE50u is only about 25N.
According to the measured data, the higher the strength of the single-layer film, the higher the puncture strength of the composite film. The magnitude of the increase is related to the structure, thickness and flexibility of the composite film.
3. Influence of processing conditions and storage conditions of composite membrane
When processing composite film, especially the composite film using nylon layer, it is necessary to control the temperature and humidity of the workshop. After the nylon film is wet, the barrier property, puncture resistance and processing adaptability will be greatly affected. If the storage conditions are not satisfactory, the composite membrane may be affected by moisture or corrosive gas, which may also affect the puncture strength of the composite membrane.
4, test conditions affect
The test conditions can not fundamentally improve the puncture strength of the composite film. If the test conditions and test methods are not in accordance with the standard requirements, it may bring a large test error. The original qualified material, due to the influence of the test, reads the data deviation. Standards, cases of artificial failure.
5, the impact of the use of conditions
This is the most likely controversial place. If the standard test method is used, the puncture strength data tested by the composite film is qualified and meets the standard requirements. In actual use, there is a case of puncture of the composite film, which is often controversial. The composite film processing party believes that the puncture strength is acceptable, and the composite film user believes that the index is unqualified, although it is qualified from the data, Can not meet the requirements of use, and is often considered to be unqualified products.
6, the direction of puncture
Puncture from the inner and outer sides of the composite membrane. If the material structure is asymmetrical, the strength values are different, such as BOPA15u//BOPA25u//AL7u//PE50u. The puncture strength from the BOPA15u side is about 25N, and the puncture strength from the PE50u side. It is about 23.5N. If it is a symmetrical structure, such as the material structure of PE50u//BOPA15u//AL12u//BOPA15u//PE50u, the strength is basically the same regardless of the side piercing. Therefore, when standard and actual tests are formulated, Consider the direction of the puncture.
The influence of other uncertain factors mainly refers to the anti-puncture abnormality caused by the conventional use, testing, storage and transportation.