TPX™ (methylpentenecopolymer)

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TPX is a specially designed crystalline polyolefin with outstanding heat resistance, reliability and transparency.

Precautions in Processing TPX

  • TPX is made available in form of pellets.
  • Since TPX does not absorb water / moisture, it is not necessary to dry TPX before processing provided that it has been stored under normal conditions.
  • Because of its high melting point TPX is normally processed at high temperature being in a range of ± 300℃ . A moulding equipment which can be set to such temperatures is therefore a basic requirement.
  • To control / minimize the decomposition of TPXit is recommended to apply nitrogen-feeding at the hopper during moulding process.
  • Unlike PC, PMMA and other amorphous resins TPX is cristalline and is therefore showing a bigger mould shrinkage. To this fact special attention has to be paid in case an existing mould , which has been designed for any other resin, will be used for the processing of TPX.
  • Before starting to process TPX please be sure that no other resin is remaining in your machine. Particularly in case of injection moulding even a small amount of foreign resin will result in an impair appearance of the product due to contamination. It is generally recommended to purge the equipment first with PP of low MFR and afterwards with TPX.

Injection moulding:

When TPX is in a melted state its viscosity declines drastically. Because of this a pin gate is the most suitable gate for injection moulding. This will help to minimize deformation and stress in the gate area. Particularly for shallow products an off-center gate is highly recommended to avoid warpage. Injection moulding of TPX is normally done within a range of 290 ℃ and 310 ℃ where 280 ℃ and 320℃ have to be regarded as lower and upper limits.
For a good controlling it is generally recommended to measure the actual resin temperature. Because of the very low viscosity of TPX at melted state it is also strongly recommended to inject at very low speed and very low pressure to minimize stress. The mould temperture is normally set within a range of 20℃ and 60℃ .

Extrusion:

Because TPX needs a lot of energy to melt an extruder with a L/D ratio of at least 28, preferable 30 or 32, and with minimum 4 heating zones is strongly recommended.
Also a special screw-design will allow you to easy process TPX. If desired, MCI will help you to find the optimum screw-design for your machine.Sometimes a preheating of TPX-pellets can be helpful.

Blow moulding:

Because the viscosity of TPX declines sharply after it is melted, the blow moulding of TPX is rather difficult and limited to the direct blow moulding process. For the same reason the injection blow moulding process does not work! It should be noted that the transparency of blow moulded TPX -products is inferior to those made by injection moulding.

Post-processing and colouring:

Because of its very low surface tension TPX has to be pre-treated with e.g. corona, flame, plasma, etc., for printing, painting or bondig it. Moreover, since TPX is low in mechanical strength, it is unsuitable for cutting manufacturing. TPX can be coloured by dry blending and the most suitable way is to use a colour masterbatch based on TPX. However, please be sure to select pigments with high heat resistance, exceeding the moulding temperature of TPX.