What are the common problems of plastic bottles

Plastic bottles are low cost, not easy to break, good transparency, food-grade raw materials and other characteristics, and are widely used. It is a common packaging container in the cosmetics, food, and beverage industries. So, what are the common problems with plastic bottles:

1. When designing squeeze plastic bottles, if the material is high-density polyethylene or polypropylene, the cross-section of the plastic bottle should be rectangular or oval. For low-density polyethylene or other flexible plastic bottles, the cross-section It is better to be round. This makes it easier for the contents to be squeezed out of the plastic bottle. The plastic parts used in conjunction with the plastic bottle mouth are mainly bottle caps and sealers.

The design of the plastic bottle mouth should be focused on; consider how to make the plastic bottle mouth better match the lid and sealer to the bottom of the plastic bottle, which is the weak part of the mechanical properties of the plastic bottle. Therefore, the bottom of the plastic bottle is generally designed to be concave; the corners of the plastic bottle, and the concave part, are all over the larger arc. In order to facilitate the stacking of plastic bottles and increase the stacking stability of plastic bottles, the bottom of the plastic bottles should be designed with internal grooves.

2. When using labels on the surface of plastic bottles, the labeling surface should be flat. A "frame" can be designed on the surface of the plastic bottle, so that the label can be positioned accurately without movement. In blow molding, the first part of the parison that is blown into contact always tends to harden first. Therefore, the wall thickness of this part is also larger. The edge and corner part is the last contact part of the parison inflated, and the wall thickness of this part is small. Therefore, the edges and corners of the plastic bottle should be designed with rounded corners. Changing the surface shape of the plastic bottle, for example, the middle part of the plastic bottle is relatively thinner, and increasing the circumferential groove or rib on the surface of the plastic bottle can improve the rigidity and bending resistance of the plastic bottle. Longitudinal grooves or ribs can eliminate deviation, sagging or deformation of plastic bottles under long-term load.

3. The printing surface of the plastic bottle is the most concentrated part of consumers. The printing surface should be flat and continuous; if the plastic bottle contains handles, grooves, ribs and other structures, the design should be careful not to cause inconvenience to the printing operation. Oval plastic bottles have higher rigidity, but the manufacturing cost of the mold is higher. Therefore, in order to ensure the rigidity of the plastic bottle, in addition to selecting a material with high rigidity, the shape of the plastic bottle must be designed to enhance the rigidity and load resistance of the plastic bottle.

4. Since most plastics have notch sensitivity, plastic bottles are prone to cracks and cracks at sharp corners, roots of mouth threads, necks, etc., so these parts should be designed with rounded corners. For the transfer place of the rectangular plastic bottle, it is necessary to support most of the load of the plastic bottle, so locally increasing the wall thickness at this place is also beneficial to improve the rigidity and load-bearing strength of the plastic bottle.