Why is there a layer of adhesive film in the kraft paper bag of the woven bag manufacturer?

The kraft paper bag produced is made of kraft cloth and paper plastic through a series of equipment processing. But in our daily life, some food industries have met that there is a layer of adhesive film in the kraft paper bag, so why is there a layer of adhesive film in the kraft paper bag of the woven bag manufacturer?

For the food industry, kraft paper bags are selected because they are environmentally friendly and will not pollute the food. However, why do some kraft paper bags have a layer of plastic film? This is because, in order to prevent water, during the sale or transportation of food, the outer packaging bags will appear watermarks or wet due to one or another problems, which is easy to tear by hand, Or the product is inadvertently exposed, so many food industries will use a layer of adhesive film.

In addition, in our daily life, we see that some food kraft paper bags are relatively thin, while others are relatively thick. This is because customers ask woven bag manufacturers to design them with different material requirements, some of which require three layers, others require multiple layers, and so on.