Factors Affecting the Puncture Resistance of Composite Membranes
Puncture resistance, also known as puncture resistance, is a very important physical property index of composite membranes, which reflects the maximum resistance to puncture of composite membranes when subjected to forces from the inside or outside of sharp objects. The processing and use of ordinary composite films often do not pay much attention to this indicator, but for some special purpose composite films, this indicator is very important. Ignoring this point can easily lead to batch quality accidents and serious losses. The following is a brief discussion on the factors affecting the puncture resistance of composite membranes.
Puncture resistance, also known as puncture resistance, is a very important physical property index of composite membranes, which reflects the maximum resistance to puncture of composite membranes when subjected to forces from the inside or outside of sharp objects. The processing and use of ordinary composite films often do not pay much attention to this indicator, but for some special purpose composite films, this indicator is very important. Ignoring this point can easily lead to batch quality accidents and serious losses.
The following is a brief discussion on the factors affecting the puncture resistance of composite membranes.
1. Material selection
The factors to consider in selecting materials are to first determine the material structure in order to meet the puncture resistance. For example, to increase the puncture resistance, whether it is necessary to add a nylon layer, and whether the surface layer should use a PET film structure or a PA film structure. In comparison, using a composite film with a nylon layer will significantly improve the puncture resistance. When 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 resistance of the composite membrane; The selection of composite glue and the determination of coating amount vary due to the different characteristics of the glue. After complete solidification, some glue will harden the composite film, while others will make the composite film softer. Composite films of the same material and thickness have significant differences in hardness and hardness, resulting in significant differences in puncture resistance.
2. Effect of single layer membrane on puncture resistance
The ultimate puncture resistance of composite membranes is directly related to each single layer membrane. The puncture resistance of composite membranes can be determined by each single layer membrane, and the strength of all single layers must meet the standard requirements. The puncture resistance of composite membranes is not a simple superposition of the puncture resistance of single layer membranes, but there are complex mechanical factors, such as the single layer BOPA15u being 8.5~12.0N; BOPA25u is 16.0~19.0N, but the puncture resistance of the composite membrane structure BOPA15u//BOPA25u//AL7u//PE50u is only about 25N.
According to measured data, the higher the strength of the single layer membrane, the higher the puncture resistance of the composite membrane. The magnitude of the increase is related to the structure, thickness, and flexibility of the composite membrane.
3. Effects of processing and storage conditions on composite films
When processing composite films, especially those that use nylon layers, it is important to control the temperature and humidity in the workshop. When the nylon film becomes damp, its barrier, puncture resistance, and processing adaptability will be greatly affected. If storage conditions are not ideal, moisture or corrosive gas contamination of the composite film can also affect the puncture resistance of the composite film.
4. Impact of test conditions
The test conditions cannot fundamentally improve the puncture resistance of the composite film. If the test conditions and methods are not carried out in accordance with the standard requirements, it may lead to significant test errors. Due to the impact of the test, the reading data of otherwise qualified materials deviate from the standard, resulting in artificial disqualification.
5. Impact of usage conditions
This is the most likely controversial point. If the composite membrane is tested according to standard test methods, the puncture resistance strength data are qualified and meet the standard requirements. During actual use, there is a situation where the composite film is punctured, which often leads to disputes. The composite film processing party believes that the puncture resistance strength is qualified, while the composite film user believes that this indicator is unqualified. Although it is qualified from the data, it cannot meet the use requirements, and is often considered as a nonconforming product.
6. Direction of puncture
When puncturing from both sides of the composite membrane, if the material structure is asymmetric, the strength value is different, such as BOPA15u//BOPA25u//AL7u//PE50u structure, the puncturing strength from BOPA15u side is about 25N, and the puncturing strength from PE50u side is about 23.5N. If the material structure is symmetric, such as PE50u//BOPA15u/AL12u/BOPA15u/PE50u material structure, the strength is basically the same regardless of which side is punctured, Therefore, when formulating standards and conducting actual testing, the direction of puncture should be considered.
Other uncertain factors mainly refer to anti puncture abnormalities caused by routine use, testing, storage, and transportation.