PET system:PET bottle neck crystallization system

Possible to crystallization even after blowing

Heat resistant more than 70 deg C is ensured by neck finish crystallization of blown PET bottle


PET Bottle Neck Crystallizer

Necessity of Crystallization of PET Preform Neck Finish

Generally, The PET resin begins softening in the temperature of 70 degC or higher temperature. This softening temperature is so called TG (grass transition temperature) of PET. Supposing that when PET bottle leaving in more than 70 degC atmosphere, the bottle neck will start softening and almost the dimensions will shrink also the deformation of the neck finish will be occur at the same time.

Specially the demand in the beverage market such as fruit juice, oolong tea, coffee drinks and lactic acid drinks are expanding in recent years. However, almost the beverage are filled into the PET bottle at the high temperature of more than 85 degC, just after that, the PET bottle capped on the filling line conveyor then, handstand the bottle to sterilize the inside of neck finish with the high temperature content liquid for some time.

Therefore, the neck finish of PET bottle must be withstanding the condition of the high temperature atmosphere. Normally the state of PET preform neck finish is amorphous because of it molded by injection molding and that's why it does not have heat resistant at more than 70 degC. In other words, this neck finish will have shrinkage of the dimensions and the shape deformation in the hot filling, and it bring about the fatal defect for PET bottle such as micro leakage.

But, PET has the characteristic to become heat resistance when it crystallized. The density of amorphous PET is 1.365 g/cm3, but forget the heat resistant, it becomes the higher density when making progress the crystallization from 1.365 to 1.380 (crystallinity index 25 % to 39 %).

Our equipment system, which was developed in this time, the crystallization of the neck finish of PET preform makes progress to get the heat resistant.

Heater Unit & Bottle Fix Device (Heater Chuck)

The bottle hold chuck processed into the best form to heat the bottle neck receives a bottle from the feed loader and holds it properly. Next, when the heater lowers, the feed loader returns to its original position at the same time and holds the next bottle. The heater, sitting at the specified position, heats the bottle neck gently for the preset time.

System Features

  • 1. The bottle neck heating module has the mechanism to keep the positions of the bottle hold chuck and the heater in the best condition.
  • 2. Heating of this system is of low capacity heating type, allowing smooth and gradual crystallization of the bottle neck without distortion and also making life of the heater much longer.
  • 3. The heater unit has a simple structure without any moving part.
  • 4. The heater unit is stationary "non rotary neck heating type", which means we have realized "uniform quality heating".
  • 5. This mechanism does not require forced cooling for heating and crystallization.
  • 6. The heating process allows a high degree of setting freedom without any restrains from the other processes.
  • 7. Mechanism decreasing heat transfer from the heater as possible.
  • 8. Auto operation excluding the heater rows out of use is possible, improving productivity.

Inside Diameter Fixed Core & Pulling Process (Pin Chuck)

When heating finishes, the bottle neck gets crystallized. Immediately after the heater rises to its original position, the pin air cylinder inserts the pin into the bottle neck for the preset time to prevent shrinkage of the neck, ensuring the proper inside diameter.

System Features

  • 1. Slide mechanism to guide the bottle neck and the pin axis accurately and properly.
  • 2. Simple mechanism arranging the bottle neck, the pin and the heater on the same axis, allowing process by their moving only on the same one axis.
  • 3. The pin insertion process allows a high degree of setting freedom without any restrains from the other processes.
  • 4. Structure consisting of the impact pull out coupling and the bottle hold chuck allows pulling out the pin perfectly.