Mold Coating Permanent Release Coatings

These are 1) a permanent release coating on the mold, 2) an internal release agent added to the reaction mixture, 3) a combination of a permanent base coat with an occasionally renewable top coat, and 4) a renewable release coat applied every cycle or every few cycles. The options are listed in order of desirability from a production point of view. Option 4 is in fact what nearly everyone uses, by necessity. Once Option 4 is accepted, it is reassuring to know that excellent release agents are available which can provide smooth, automatic production. 

Molded urethane technology in the immediate future should not be limited by mold release considerations, but the role of the mold release in new systems should be considered early in the plans. Regulations for air quality control and worker safety are expected to create a continuing shift to water-based mold releases, or at least some means of greatly reducing the amount of solvent evaporated. Some progress seems likely in use of semi-permanent release coatings which can be renewed by periodic application of a top coat. 

Inside the 3,000-mm big spider, clamping of the single molds is done using special pneumatic cylinders. For an optimal heat transfer, the aluminum molds are provided with so-called Profit Pins and a permanent release coating. 

Siloxane performed better than fluorocompoimd as an external release agent. Mold fouling occurred after 150 cycles (compared with 10 cycles for fluorocom-pound). The best performance (more than 600 cycles without maintenance) was obtained with permanent teflon coatings. 

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