When surface of the plastics bottle is labeled, the label surface should be smooth. In blow moulding, the first contact part of billet inflation always tends to harden in advance. Therefore, the wall thickness of this part is also larger. The edge and corner are the last contact parts of billet bloating, and the wall thickness of this part is smaller. Therefore, the edges and fillets of plastic bottles should be designed into rounded corners. The rigidity and bending resistance of plastic bottles can be improved by changing the surface shape of plastic bottles, such as thinner middle part of plastic bottles and increasing circumferential grooves or ribs on the surface of plastic bottles. Longitudinal grooves or reinforcing bars can eliminate the displacement, sagging or deformation of plastic bottles under long-term load.
The printing surface of plastic bottles is the part which can mostly draw consumers’ attention. The printing surface should be flat and continuous. Elliptical plastic bottles have higher stiffness, but the manufacturing cost of the mould is higher. Therefore, in order to ensure the rigidity of plastic bottles, besides choosing materials with high rigidity, the rigidity and load-resistant strength of plastic bottles should be strengthened through the shape design of plastic bottles.
Because most plastics are sensitive to notches, plastic bottles are prone to cracks and cracks at the sharp corners, the root and neck of the thread at the mouth, so these parts should be designed into rounded corners.