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news-Discussion on the cause of the adhesion on the end surface of BOPA film - a case series of spec
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Discussion on the cause of the adhesion on the end surface of BOPA film -- a case series of special quality of BOPA film
2019-01-03

Not long ago, we received feedback from customers in foshan, guangdong province: the nylon film roll produced the film break during the use. When the machine was stopped, we found that the BOPA film had a neat end surface, but there was a small resin transparent and dry adhesive attached to the end surface of the film roll, resulting in the film break.


There is no chance of meeting resin or adhesive in the production of nylon film. Where does this dried adhesive come from? It is suggested that both parties should find out the reason in detail, as it is a long-term cooperative unit.


I. reasons for film break at the end of film roll:


BOPA film is a bidirectional stretch film, and this type of film has a feature that after bidirectional stretching, the tear strength of the film is very large, but the secondary tear strength is greatly reduced. As long as the cutting knife mark, notch or other defects on the film surface are left, it is easy to tear under the printing or composite tension. Generally, the lateral tensile force of directional plastic film is relatively small, and it is easy to cause the film breaking when encountering small gap, knife mark and scratch by external force. The reasons for the film breaking of directional plastic printing film roll are as follows:


1. Severe cross-tomography. The film slippage or the film width changes during the film rewinding process. This phenomenon is related to the cutting speed and can be easily seen from the end surface. If the fault layer is too large, it will cause lateral tension instability and rupture of the film.


2. Face injuries. If scratch, bruise, cutting blade is not sharp, resulting in serrated cross blade or other surface fault, etc., the film will be broken by external tension.


3. Low tensile and fracture force due to the quality of the membrane itself; Or a large number of additives on the surface of the upper surface of the film is particularly rough, the friction coefficient is too large, the tension imbalance produces broken film, or the film surface with large crystal point plasticizer and other foreign matters.


4. Equipment reason or production process reason.


Ii. Case reasons:


It is very rare to produce the adhesive film in the white roll film, because there is no chance to meet the adhesive in the film production and printing process. So-called sticky side, it is to be in dry type is compound commonly, plastic film passes besmear on glue to be heated dry by drying channel after drying, again after hot press steel roll is extruded, the phenomenon that both sides of rewinding finished product sticks together. After the adhesive failure of the finished product, it will be difficult to separate the finished product film by firmly bonding between the film layers at both ends of the coil material. Especially when using two-component two-fluid reactive adhesive, it is most likely to appear. In serious cases, the composite product will be pulled and deformed, resulting in product scrap.


The film manufacturer and the film using manufacturer have not found any practical clues from various aspects, such as production process, field record, inventory goods at the same time, etc., only to check the film breaking model on the cutting record that there is the blade change record on the day, and the film roll produced before and after the blade change has no bad feedback. Later, another manufacturer feedback also exists when white roll film printing, and the film is broken. After the search, two broken film in the same work station on the same day, cut only divided into different shifts.


Therefore, the scope of film breaking and the production of adhesive edge can be reduced to the film cutting process to find the cause.


Whether the large crystal point produces film break or not, as there is no real sample left, only a small amount of transparent clay is left for testing, and the result shows that it is nylon particle material. After analysis, if the crystal point does not appear at the same cutting station at the same time, unless there is a defect in the molten extrusion die head. At present, large crystal points or plasticides were not found in the same place in the production of the large film. In the discussion and analysis with the cutting staff, one of the old staff provides a very useful clue, that sometimes cut off the shelf when found that the end is very hot and sometimes hot. If the membrane surface feels hot, the membrane must be soft. If there is an external force at this time, the edge of the membrane can be determined to produce adhesion, but whether the film will be broken depends on the degree of paste and use. The heat of the membrane will not be large to hot, then look for the source of heat from where?


Cutting machine has a control slitting width slitting knife placement of concave type keyway, its their every 5 mm stud piece of space, and when a change in the blade if the blade is installed near the gear block, after cutting and membrane fast running friction, time long heat accumulation, the greater the more result in cutting face soft interlayer membrane, and adhesion force formed by the end of the move state, and produce viscous boundary film. In fact, the customer feedback adhesive film is produced from this reason, in fact, the customer reported that the adhesive is several layers of nylon film adhesion formed. Due to the formation of the end face stick side, not easy to be found, the first is in the blade blade technology is not standard, not the blade is installed in the middle of the concave keyway in heat dissipation, avoid blade who get too close to the tank wall friction produces a great deal of heat to make soft membrane edge, after more importantly rolls off the shelves, also very hot on the membrane surface under the condition of packing pressure immediately (such as on hot side roller on compression, therefore produce white film roll end glue phenomenon. This kind of failure is rare, but it has happened, so it is put forward for reference.

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