Comparison of advantages and disadvantages of four-side sealing bag, three-side sealing bag and back sealing bag

Four sides sealed bag

After the bag is formed, the four sides are heat-sealed. The most common granule packaging form is mature in technology and simple in process. The equipment has high running stability, relatively beautiful shape, and good product sealing.

The four-side sealing bag is usually divided into two halves by a whole film and then packaged relative to each other. It belongs to the method of first heat sealing the bag and then cutting the single bag. Only one edge needs to be controlled during production to obtain a better packaging effect. Therefore, it has extremely high packaging material / equipment adaptability and packaging operation stability (this is very important, because the four-side sealing machine is usually slower than the cartoning machine, the common mode is multiple four-side sealing machine with one boxing Machine use, higher requirements for the stability of equipment operation). At the same time, since each side is heat-sealed evenly, the sealed product is better.

The disadvantage of the four-side sealing bag is the insufficient adaptability to the packaging of large-volume materials. Because the entire film is first made after the bag is cut, the composite film is required to be relatively flat during the bag making, and the bag body is flat after the bag is made. The utilization rate of space in the bag is relatively low.

Three sides sealed bag

That is, one side of the packaging bag is directly folded in half by the composite film, and the other three sides are in the form of heat sealing. In fact, the three-side sealing bag can be regarded as the supplement of the four-side sealing bag. Compared with the four-side sealed bag, the advantage is that it can be unfolded into a body bag type after being formed into a bag. The space utilization rate is high, suitable for large-volume packaging needs, and is often used for the packaging of cold granules and other products.

The shortcomings of the three-side sealing bag are also obvious. The first is the asymmetry of the bag shape caused by the three-side heat sealing, which affects the appearance. Of course, the aesthetic problems are different, and I will not discuss them here. Secondly, the packaging speed is slow. The most common packaging form of the three-side sealing machine is single-row packaging (this is also the reason why the three-side sealing is suitable for large-volume packaging, because only the single-row can ignore the flatness of the composite film), multi-row type I have n’t seen the three-side bag sealing machine, but if you can, multi-row three-side bag sealing can only be done by cutting the composite film into several pieces and then rolling them into bags separately, which is difficult to control. It is not as stable as the combination of multiple single-row packaging machines.

Back seal bag (also known as stick packaging)

That is, the roll film is first divided into several rows, and each row of composite film is rolled individually and then the longitudinal seal is pressed to one side, and then the method of horizontally sealing the bag is first invented by a Japanese company. The advantages of back-sealed bags are very obvious. First of all, the appearance is very beautiful. The hidden vertical sealing and bag-shaped characteristics adopted by the back-sealed bags determine their distinctive appearance characteristics. The bag is exquisite and beautiful. Compared with the same type of four-side sealing products Clearly differentiated advantages. Secondly, the back-sealed bags combine the advantages of four-side sealed bags with multiple rows at the same time, fast packaging speed and three-side sealed bags with high space rate utilization. Compared with four-side sealed bags, it can reduce the amount of packaging materials by about 40% without affecting the production speed , Has a very obvious packaging cost advantage.

The disadvantages of back-sealed bags are also very clear. First, the method of making the composite film first and then making each row separately determines that the back-sealing bag has the worst adaptability to the packaging material / packaging equipment. At the same time, the shape of the back-sealing bag determines its Subsequent finishing and packaging are the most difficult, so the initial investment of back-sealed bags is huge, and the cost of operation and maintenance is high (also because of the high entry barrier, which highlights the advantages of the appearance of the back-sealed bags). Secondly, the horizontal sealing position of the back-sealed bag is to seal the vertical sealing with the composite film bag, so the heat sealing is difficult, the bag sealing is lower than the four-side sealing bag, and the risk of bag sealing failure is also significantly higher than the four sides Seal the bag.

In short, whether it is a four-side sealed bag, a three-sided sealed bag or a back sealed bag ( stick packaging), has its distinctive characteristics and unique scope of application. Some features are both the advantages of its packaging form and the source of its defects. How to choose the appropriate packaging form should be decided according to the product and packaging form of the enterprise. For example, for high-volume products, the four-side sealing bag is not competent, and the three-side sealing and back sealing bags can better solve this problem.

At present, the four-side sealing bag is still the main product of the mainstream European packaging equipment suppliers. The reasons are as follows:

1. It is the pursuit of heat sealing quality;

2. It is a larger layout, which can be freely designed to improve the appearance of packaging;

3. The best business card for a product is actually the reputation of the company and the safety and effectiveness of the product. For European and American pharmaceutical companies, the cost of packaging materials is extremely low relative to the value of the product. The demand for saving packaging materials is not urgent. At the same time, the company's popularity and reputation also determine that its need to use packaging to shape its competitive advantage is not urgent. Of course, another reason is that the back seal bag originated in Japan, and European and American companies have no advantage in this field. This situation is different in China. Because it is difficult to compete fully on the reputation and product safety and effectiveness of the company, the company is more sensitive to appearance differentiation and packaging costs. The wider the application.