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Mexichem Specialty Compounds create a soft PVC-Free crown liner solution


A multinational customer, who was interested in replacing a PVC liner (for beer bottle crowns) with a PVC-free liner, approached Mexichem Specialty Compounds with a request to develop a new compound solution to meet an exacting specification. They requested that we develop a suitable TPE compound with following performance characteristics:

  • A broad processing window.
  • Good adhesion to lacquer.
  • Able to withstand sterilization for 30 minutes at 120o C.
  • Free of objectionable odour and flavour.
  • Suitable for processing on Sacmi equipment.
  • Thermally stable.
  • FDA regulated.
  • Capable of running 2,200 crowns per minute.

Mexichem Specialty Compounds accepted the challenge and developed a TPE compound to replace the current PVC product, which would broaden the process window and meet the customer’s requirement of 2,200 caps per minute.

The problem

Bottle cap liners act as a seal between the bottle contents and the external environment. They act as a sterile barrier to prevent both contaminations and to keep the product in prime condition. However, PVC liners are problematic in certain food related environments.

PVC liners allow for a high level of oxygen transmission. This reduces the shelf-life of the beer, and it also means that the same beer is experienced differently by consumers, depending on its bottle age when consumed. Beer is sensitive to oxygen, and the procedures for bottling beer are much more stringent than those for wine in terms of oxygen pick-up.

Additionally using PVC for alcohol, with an ABV (Alcohol by Volume) greater than 9%, is problematic because of fears relating to the carcinogenicity of vinyl chlorides, which could leach into the beer at that strength.


To develop a PVC Free liner for Beer pry off crowns; a compound that would meet the performance criteria set by the client, to be flavour and odour neutral (removing the risk of taste taint) and to maximise shelf-life and taste consistency regardless of bottle age consumption.

The Challenges

  • Meet FDA regulations.
  • Narrow Processing Window.
  • Fast processing speed.
  • Flavour and odour neutral.
  • Good adhesion.
  • Withstand sterilization for 30 minutes at 120o C (with no loss of adhesion)

The solution

Mexichem Specialty Compounds developed a PVC Free compound  (Alphaseal 255 H ) that ran smoothly at desired speeds, conformed to functional specifications but more importantly it also met customer’s pricing needs. The solution met all performance, temperature, and adhesion criteria and was also free of odour or taste taint. As a result, the beer would meet all regulatory standards, deliver optimal taste and maximise product shelf-life.

The results

As requested, by the client, Mexichem Specialty Compounds successfully engineered a PVC free liner to meet the demands of the beer ‘pry off ‘ market. The customer received a PVC Free product tailored to their particular and exacting need, allowing them to target new markets and grow their business in new areas both technically and geographically.

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