The main problem of plastic bottles

- Apr 20, 2018-

(1) In the design of extruded plastic bottles, if the material is high-density polyethylene or polypropylene, the cross-section of the plastic bottle should be rectangular or oval, for the material is low-density polyethylene or other flexible plastic bottle, its horizontal The cross section is preferably circular. This facilitates the extrusion of the contents from the plastic bottle. The plastic parts used with the plastic bottle mouth are mainly bottle caps and sealers. The design of the plastic bottle mouth should focus on examination; how to make the plastic bottle mouth fit the bottom of the plastic bottle with the lid and the sealer better is the weak part of the mechanical performance of the plastic bottle. Therefore, the bottom of the plastic bottle is generally designed to be concave; the corners of the plastic bottle, as well as the inner cavity, are all subject to large arc oversizing. In order to facilitate the stacking of plastic bottles and increase the stacking stability of plastic bottles, the bottom of plastic bottles should be designed with inner grooves.


(2) When the surface of the plastic bottle is labelled, the surface of the label should be flat. A "sash" can be designed on the surface of the plastic bottle so that the tag can be accurately positioned without movement. During blow molding, the place where the parison inflates first contacts always tends to harden in advance. Therefore, the wall thickness of this part is also larger. The edges and corners are the parts where the parison is inflated last, and the wall thickness is smaller. Therefore, the edge of the plastic bottle and the corner should be rounded. Changing the surface shape of the plastic bottle, such as a relatively small central portion of the plastic bottle, and increasing the circumferential groove or rib of the plastic bottle can improve the rigidity and bending resistance of the plastic bottle. Longitudinal grooves or ribs eliminate plastic bottle deflection, sagging or deformation under long-term loading.


(3) The printing surface of plastic bottles is the most concentrated part of consumers' attention. The printing surface should be flat and continuous; if the plastic bottle contains handles, grooves, ribs, etc., the design should be careful not to cause inconvenience to the printing operation. Oval-shaped plastic bottles are also high in rigidity, but the manufacturing cost of the molds is high. Therefore, in order to ensure the rigidity of the plastic bottle, besides selecting a material with high rigidity, the shape of the plastic bottle must be designed to enhance the rigidity and load bearing strength of the plastic bottle.


(4) Since most plastics have notch sensitivities, plastic bottles are susceptible to cracks and cracks at sharp corners, at the root of the mouth thread, and at the neck, so these parts should be rounded. For the transfer of rectangular plastic bottles, most of the load of the plastic bottles needs to be supported. Therefore, the wall thickness at that part is locally increased, which is also advantageous for improving the rigidity and load-bearing strength of the plastic bottles.