Analysis of PVC Die Precipitates

Ningbo Fangli Technology Co., Ltd. is a mechanical equipment manufacturer with nearly 30 years’ experiences of plastic pipe extrusion equipment, new environmental protection and new materials equipment. Since its establishment Fangli has been developed based on user’s demands. Through continuous improvement, independent R&D on the core technology and digestion & absorption of advanced technology and other means, we have developed PVC pipe extrusion line, PP-R pipe extrusion line, PE water supply / gas pipe extrusion line, which was recommended by the Chinese Ministry of Construction to replace imported products. We have gained the title of “First-class Brand in Zhejiang Province”.

There are two situations on the die of PVC-U pipes: one is white or yellow wax (oil) that appears on the die. The reason is obvious, that is, there are too many low melting point lubricants with poor compatibility with PVC, which are free to the surface of the product, and when the die is exported, it is separated from the product to the die to form white or yellowish brown wax (oil). The other is that the longer the "moustache" on the die is, the more complicated the reason is believed that the lack of lubrication in the later stage leads to the insufficient strength of the material melt and the insufficient demoulding effect. When there is too much calcium powder and too little lubricant, the lubricant is too little to lubricate the calcium powder surface, which will also cause whisker like precipitation. The precipitation of the setting sleeve is easy to occur after the use of calcium zinc stabilizer. The reason is complex or people have not yet figured it out, and it is difficult to solve it thoroughly. Whether it is possible to use external lubrication with high efficiency and high melting point as much as possible, and minimize the use of lubricants (including internal and external lubrication) on the premise of meeting processing requirements, meanwhile paying attention to melt strength and demoulding.

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