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TPE improves Wavin 2K Pipe Seal Moulding Process

Summary

Reinforcing Mexichem’s business strategy of vertical integration, Mexichem Specialty Compounds and Wavin Limited identified a synergy which brings benefits to both companies and to Mexichem.

Wavin, had been using a ThermoplasticVulcanisate (TPV) material, on a 2K moulding process, for the production of 110mm & 160mm pipe seals. This process had been in operation for 5 years. The client wished to switch to a Thermoplastic Elastomer material (TPE); however the existing TPE products did not have the compression set and shrinkage performance as the existing TPV product.

Wavin

The problem

The incumbent’s TPV material had been in production for many years, with the 2K pipe seal production cells, which had been designed around the TPV materials performance. With no wish to retool, Wavin set Mexichem Specialty Compounds the task of designing a TPE material that would perform the same (with the same tool shrinkage) working at the same 90o temperature, and would also be able to comply with EN681-2 and pass the Kiwa testing for KOMO approval.

Application

For 110mm & 160mm 2K moulding pipe seal on two production cells.

Challenges

To provide a TPE pipe seal material that would perform as well TPV and conforms to EN681-2 and Kiwa testing:

  • To have the same processing window
  • Comply to EN681-2 
  • KOMO approvals Pt1
  • To perform at the same temperature as the TPV material
  • To meet the compression set requirements
  • To reduce dust
  • To have the same flow behaviour
  • To maintain the same outputs


The solution

The TPE material had to perform as well as the incumbent Thermoplastic Vulcanisate material. To achieve this required a formulation change within the Thermoplastic elastomer material itself, to allow it to meet compression set, maintain recovery, and yet retain the same shrinkage as the TPV material.

This was achieved by changing the ratios of the SEBS oils and fillers. Trials showed that the first formulation adjustment had improved the performance, but the seals were not releasing from the tooling.

Trough R&D development a new lubricant system was introduced to help with the mouldings releasing from the tooling. The second trial showed an improvement with the cycle time, reduced tool staining and a reduction of fines in the vacuum system filters.

The Result

The EVOPRENE® Super G TPE compound performed slightly better than the incumbent’s TPV, with improvements on the cycle times, reduced fines in the vacuum filter system and reduced tool maintenance time due to reduced tool staining using the TPE material. Reducing the maintenance cycle also led to cost savings in manpower and production ‘down time’. With a reduced cooling time per seal, productivity improved on the production cells.

Mexichem Specialty Compounds' compound passed the necessary KOMO part 1 approvals and conforms to the EN681-2 standard.