Stubborn packaging will punish everyone who has no scissors at hand. It is clearly written that ' tear along the serration ', but the serration is just like a decoration, not only can 't be ripped by hand, but even the teeth can 't let it yield. What is the problem ? Why do some packaging bags have serrations that cannot be torn open, and some without serrations can be easily torn open ?
01 can not be torn always marinated eggs ? The most common snacks that are difficult to be torn by spit packaging are usually sausages, marinated eggs, and board bars. Their common point is that they are vacuum-packed. This kind of packaging is difficult to tear may be to ensure product qualit
Vacuum packaging removes air during packaging, which allows the oxygen content in the bag to become very low. When the oxygen content decreases from 21 % to 0.5 % -1 %, the reproduction of most aerobic bacteria and fungi is inhibited. Therefore, vacuum packaging can play a role in anti-corrosion and preservation, so that the shelf life of food is greatly extended. In order to keep fresh smoothly, vacuum packaging bags must be kept in a highly sealed state for a long time. This requires the packaging bag to meet two conditions at the same time : first, the material itself can prevent gas penetration ; second, the bag should be very complete, not damaged. In the production and transportation, the surface of the packaging bag may appear small cracks. If the packaging material is too easy to tear, these small defects can easily expand, leading to packaging damage.
Any damage will destroy the seal, leading to oxygen entry, so that the vacuum packaging of food spoilage ahead of time - this is much more difficult to tear than packaging quality problems. Therefore, manufacturers will always give priority to ensure that the packaging bag is strong enough to sacrifice the tearability.
02 why there are serrated can not be torn open ? The presence of serrations and cuts can help the stress ( the force per unit area ) to concentrate to a point, making the packaging easier to tear. But even with this design, things that cannot be torn apart from the packaging still occur from time to time.
Packaging tearing may be caused by the following reasons : if it is not torn from the beginning, it may be easy to tear the mouth design is unreasonable, such as saw teeth do too shallow. A more common situation is that it is torn open at the beginning, but it can no longer be carried out halfway. This may be because the packaging uses materials with good tear resistance, such as linear low density polyethylene. This kind of material has good flexibility and ductility, and it will be greatly deformed and difficult to crack when it is torn. Also sometimes, it is the stratification of the packaging bag that hinders the tear. In order to achieve the best protection performance, packaging bags are often made of multiple layers of different materials. If the bonding between the materials is not close enough, the packaging bag will delaminate when it is stressed.
And sometimes, the problem lies in the direction of the tear. Ordinary packaging materials can not control the direction of tearing, which sometimes leads to cracks too large things spilled, but also sometimes lead to packaging can only tear off a corner, and can not fully open.
03 How to improve ? The simplest way to improve the tearability is to change the design of the tearable mouth, such as turning it from a serrated to a tearable line across the packaging bag. This kind of easy tearing line is made by laser. The laser can cut the outer layer of the packaging material, so that the force required for tearing is greatly reduced. At the same time, it also allows the inner material to remain intact, so as not to destroy the sealing of the packaging. Some packaging bags do not have any easy to tear, but they can still be easily torn open. This situation is that the manufacturer has improved the performance of the material itself. By adjusting the production process, the molecular arrangement and crystalline state of the plastic film can be changed, and the tearing performance can be greatly changed without changing the chemical composition. In this way, films with different transverse and longitudinal tear strengths can be processed, so that the tearing direction of the packaging can be controlled.
The packaging that can be neatly torn without easy tearing, however, the increase in tearability also means that the firmness of the packaging bag will be somewhat reduced. In the case of high tear strength requirements such as vacuum packaging, there is another solution : completely abandon the tear, and change the opening method to uncover from the middle of the two films. Now, some vacuum-packed food has been changed to open design. By adjusting the heat sealing layer formula can make it easier to uncover. Good packaging should meet the requirements of 'tight sealing 'and 'easy opening 'at the same time, but these two requirements are contradictory, and it is not easy to find the best balance point. It is hoped that more advanced tear / open technology can be popularized as soon as possible, so that we no longer need to rely on the power of scissors and teeth when eating snacks.
