The shape of the bottle is mainly related to packaging materials, Plastic beverage bottles are mostly PET bottles, they use blow molding technology. Round bottles are most convenient for mass production, and other shapes include square shape are inconvenient for blow molding, even a square bottle like ice tea bottle, actually its border is circular, it can't completely is square.

As the milk must be sterilized, we use what we call the lile packing (Of course, it's not all of it now, but the earliest use of this packaging is for lile, so it's named). This is a composite of paper, polyethylene and aluminum foil.

The paper accounts for about 70% of the packaging, so it is similar to the nature of the paper. If you know the paper packaging, it's easy to know that the most convenient form of paper is the square shape, just fold along a few lines of indentation, and a piece of paper can be made from the bottle and lids of the box. If you want to make a round bottle out of paper, just roll the body, but it's very complicated to seal at both ends, and not easy to fit, it's basically impossible to automate, and it consumes a lot of material, So no one wants to make the paper box round.

And then again, Why should plastic bottles be blown into a round shape, and does’t a square one will make transportation more efficient? There are many reasons, round bottles are easy to produce and save material, and the area of the round bottle is larger than the square one based on the same circumference.

The cost of packaging of mineral water and coke is higher than its content, province this can save a lot of money. In addition, round bottle is easiest to operate on the automatic assembly line. Filling, automatic labeling and packaging can all be automated, so round beverage bottles are more common.