PRODUCTION OF POLYETHYLENE TEREPHTHALATE BOTTLES
A Polyethylene terephthalate bottles are very commonly found to be used as a storage material for most liquids like water, juice, transport liquids like petrol etc.,
The manufacturing of polyethylene terephthalate bottles, generally use two different methods. They are as follows:
- One step “hot perform” process
- Two step “cold perform” method
Step-one “hot perform” method
This particular method takes only one step. Starting from polyethylene terephthalate granule to the end product, the complete process of making a polyethylene terephthalate bottle takes place in one single machine. The machine is integrated, so as to offer optimum efficiency. This starts from the injection into perform to the removal from the perform. It then proceeds to the injection cavity and to stretch more to create the bottle all in machine. The complete process demands a high temperature to be maintained because there is a need for the bottle to be in an elastic form when it is injected and molded. This particular method is optimum for saving a lot of energies because the content of the material demands to be heated just once. This heating process is conducted during the injection in to the cavity to create the perform. For most of the small and medium sized polyethylene terephthalate production firms, this one-step method is highly applied. PET Bottle Making Machine is useful.
Step-two”cold perform” method
The “cold perform” method has 2 varied machines to function. From perform to injecting to the blow moldings. In the first machine, the perform is injected in the form of the shape and later the perform is reheated. It isn’t brought near the blow molding machine in the first step but later. This particular method might not deem to be very vital due to the fact that the loss of heat can easily be regarded as loss of energy. Yet, the machine stands to be completely automated. This particular medium is highly used in many of the medium to large level polyethylene terephthalate production firms. This also means that the machine is highly effective (around 200% effective) over the “one-step” machine.In most cases the two step method is the preferred method for the manufacturing of polyethylene terephthalate bottles. PET Bottle Making Machine is used.
Drying and dehumidifying:
Polyethylene terephthalate plastic is very common for its absorption of moisture. The average water content being 0.05%. For the purpose of increasing the quality of the perform in transparent bottles as well as the physical performance, the polyethylene terephthalate is dried to minimize the water content of the polyethylene terephthalate resin. This minimization is to the level which is less than or equal to 0.005%. PET Bottle Making Machine
The process of drying is as mentioned below:
- Oven Dry – Maintaining a temperature of 110℃, the process of drying is conducted for around 8 hours. Proceeding this time duration, there are chances that the polyethylene terephthalate will began to fail. The trays in which the polyethylene terephthalate are placed inside the oven remains to be around 50mm thick. The oven is failed to be connected to the injection machine along with the manual movement of the dried polyethylene terephthalate.
- Hopper dryer–This is the most commonly used process for drying the polyethylene terephthalate because of its economical quality along with autoloader. This makes the process to remain constant and automatic. Part of the PET Bottle Making Machine.
- A Dehumidifier –Mirroring the hopper dryer method, dehumidifier also functions along with autoloader. It can also be said as the most effective manner of drying. At a temperature of 32℃, the polyethylene terephthalate dries. This in turn increases the sturdiness as well as the final finish of the polyethylene terephthalate bottles. The right drying temperature must be around 150℃ to 170℃. The most optimum duration for the drying of polyethylene terephthalate would be around 4 hours. The time of frying must not surpass 7to 8. If the duration extends, then it might affect the quality of polyethylene terephthalate. A segment of the PET Bottle Blowing Machine
Injecting molding of the polyethylene terephthalate perform
The process of injecting is simple. The heated polyethylene terephthalate in the molten level is injected into the chamber of injection. This done by revolving the screw barrel that is placed within the machine until the chamber remains full. After the chamber gets filled, the screw is then pushed ahead to fill the injection hole with molten plastic by using a nozzle fixed inside a mold. There are varied temperatures present within the injection molding machines. In the rear end of the machine, it must be 275℃. The middle part of the machine must maintain a temperature of 282℃. While the nozzle remains to be around 280℃. The temperature of the runner must be around 270℃. This will help in getting maximum details within the manufactured bottle. (There are chances of having a differentiating temperature based on the design of the mold).
Following it, the molten plastic in the mold that is called as perform, must be cooled. The cooling water that must be used for the process of cooling the perform, must remain within the temperature level of 15-20℃. There is a need for the pressure to be in control as well. This is the reason for the use of water chiller. The pressure must remain within the range of 500,000 PA or 5 Bar. The polyethylene terephthalate perform is ejected from the mold. The perform of the polyethylene terephthalate is again reheated to a temperature that is perfect for the process of blowing. PET Bottle Blowing Machine part.
Stretch Blow Molding of the polyethylene terephthalate Perform to the Container
The next step of production in a polyethylene terephthalate bottle of Blow molding is called Stretch Blow molding. In this method, the polyethylene terephthalate bottle is stretched by blowing air into the preheated polyethylene terephthalate Perform. PET Bottle Blowing Machine
These are the most common ways that are used for the manufacturing of a polyethylene terephthalate bottle in most parts of the world.