What is the requirement of plastic container molding?
The hollow blow molding of plastic container has two aspects as follows.
(1) general requirements for production technology.
The plastics used in China should have good compatibility with additives and concentrated masterbatch (concentrated masterbatch and functional masterbatch) and be plasticized evenly.
Rather than a single plastic or blend, it has uniform melt plasticization and smooth surface.
The melt has sufficient flow capacity and thermal stability in the temperature range of the forming process.
The blank is not easy to droop, and has better quality and length of repetition.
Mulch even in high - speed drawing billet, plastic billet should have sufficient tensile strength.
The blank has enough heat sealing strength, so that the bottom of the container is not cracked easily when the blank is blown or shaped
The blow molding container can be processed again.Each batch of plastics has a stable, repeatable molding performance.
(2) requirements of molding method on plastics.
Extrusion blow molding molding.The plasticizing of molten material, the melt in the flow channel (such as mold core, diversion comb) 屮, be able to merge has no obvious seam line, stable parison;The phenomenon of self-weight droop is not obvious and has sufficient strength of melt.The clamping section of mold blank has good welding ability.The melt flow rate of material is low.
Injection blow molding, stretching blow molding.The melt flow rate of materials is high, the melt is easy to flow, low viscosity, and can be filled with thermal flow rapidly.The melt strength is lower than that of extrusion.
Multilayer blow molding.In the case of multi-layer co-extrusion blow molding, the material of co-extrusion should conform to the composite requirements of each layer.The adhesive layer should have sufficient adhesion;The barrier layer should meet the product barrier and product performance requirements;If the supporting layer adopts materials with high melt strength, other layers can use materials with low melt strength.The melt flow velocity of material is low, and the droop phenomenon is not obvious.