How To Make Plastic Bottle?

How To Make Plastic Bottle?

To begin with, let’s answer this question “Which materials are used to make cosmetic plastic bottles?”

Plastic bottles are mainly made of polyethylene or polypropylene and other materials with various organic solvents added. Plastic bottles are widely used polyester (PET), polyethylene (PE), polypropylene (PP) as raw materials. After adding the corresponding organic solvent, they are heated at high temperature and finally formed into plastic containers by blow molding, extrusion blowing or injection molding.

The first stage of a typical two-step reheat and blow molding machine (RBM) manufacturing process is injection molding. The plastic pellets are plasticized in the barrel of the injection molding machine, and the plastic is melted by heating and the shearing action of the feed screw. The plastic is then injected into a multi-cavity mold, where it takes on the shape of an elongated tube. These tubes, called parisons, usually consist of formed necks and lines that will be used to cap oncoming bottles or preformed, which are easily shipped to bottling facilities because they are more compact than fully formed bottles.

During the reheating process, the blanks are loaded into the feeder and passed through a descrambler that directs the blanks into the blow molding machine. After being heated by a quartz heater, it enters the mold. Thin steel rods, called mandrels, are slid onto the neck of the semi-finished product, the semi-finished product is filled with highly compressed air, and stretch blow molding begins: due to the heat, and pressure of the compressed air, the parison blows, and the stretch die axially and radially , which assumes the shape of a bottle. This process creates the so-called biaxially oriented bottle, which provides an ideal carbon dioxide barrier for carbonated beverages.

The mold must cool quickly so that the newly formed part can be properly shaped. There are several direct and indirect cooling methods that can effectively cool molds and plastics. Water can flow through the pipes around the mold, thereby indirectly cooling the mold and plastic. Direct methods include the use of pressurized air or carbon dioxide directly on the mold and plastic.

Once the bottle (or in continuous production) has cooled and solidified, it can be removed from the mold. With a continuous molding process, the bottles need to be separated by trimming the plastic between them. If a discontinuous process is used, sometimes excess plastic seeps into the mold during manufacturing and needs to be trimmed. Once the plastic bottle has been removed from the mold and excess plastic has been removed, the plastic bottle can be shipped or filled.

Other bottle manufacturing processes combine preform formation and blow molding in a single continuous process. One of them is a continuous extruder, where the extruder continuously produces billets. In the extrusion blow molding process, the wall thickness of the profile is changed by changing the size of the extrusion hole of the profile. The two halves of the mould cover the suspended module and transfer it to the blow moulding station where the bottle is formed, as in the second step of the RBM process described above. Changing the wall thickness can solve the problem of uneven suspension, otherwise the weight of the forming part stretches the hot and still forming part above. Therefore, the wall thickness increases as the block is formed, resulting in a uniform thickness throughout the formation

Another manufacturing process is the reciprocating blow molding machine. These machines move the screw linearly inside the ejector barrel to accumulate bullets. The screw then pushes the bullet through the mandrel to create the parison, which is then formed in the usual way. This type of machine is typically used to make the ubiquitous high-density polyethylene (HDPE) handle milk jug first produced by Unilever in the 1960s.

This article briefly introduces the production process of plastic bottles and the raw materials of plastic bottles. For more information on related products or processes, please private message ROSE PACK to view specific product details.