ASB has been continually developing and refining the double blow heat-setting method over more than two decades.
Containers produced by this method have unique properties that expand the uses of PET resin into new market segments.

Applications

  • Heat-Set bottles and jars are commonly used for filling juices, teas, pickles, sauces and other bacteria sensitive products under pasteurized conditions. Typical filling and / or pasteurization temperatures will vary from 65 to 95°C* depending on the product to be filled.
  • Heat-Setting can also be applied to returnable / refillable containers that need to be rinsed at high temperatures. This minimizes shrinkage and adds other advantages to the container such as improved stiffness and scratch resistance.
  • Depending on the machine model used, up to 20 liter (5 US gallon) bottles can be molded.
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Preforms are Molded

pic_02A PM Series preform molding machine may be used to injection mold the preform (as per normal 2-step molding). If neck crystallization is required, the molded neck diameter will typically be slightly larger than the target neck size.


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Preform Neck is Crystallized

pic_03-1A CM Series neck crystallizer is used. For bottles, crystallization is not always required; the requirement depends on neck design, filling procedure and what type of cap is to be used.


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Container is Blown

pic_04Using one of our HSB Series blow molding machines, the preform is re-heated and stretch blow molded. Refer to the following three steps for details of the HSB process.


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Re-heating

pic_05-1The preform is re-heated to a temperature suitable for stretch blow molding. Up to this point, the molding process has been identical to conventional 2-step stretch blow molding but now it becomes different.


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First Blow Mold (Hot)

pic_06In an HSB Series machine, the primary blow mold is electrically heated in excess of 175°C, it is also larger than the target container size by around 20%. After blowing is completed, the pressurized air is exhausted from the container but the blow mold remains closed a little longer. The high temperature causes partial crystallization of the molded container, additionally, the container shrinks which has the effect of removing stress from the PET polymer chains.


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Second Blow Mold (Conditioned)

pic_07The shrunken and partially crystallized container is transferred into the secondary blow mold where it is blown to the final shape. This mold is temperature conditioned to around 100°C. The final container leaves the mold with a high percentage of crystal growth and low stress. In the case of hot filling, the container has the ability to be hot filled at up to 95°C*or withstand pasteurization after filling.