PROCESSING | PURGING COMPOUNDS
a temperature range of 160–329°C (320–625°F). Meanwhile, Dyna-Purge RF is formulated for
pre-screw-pull purges. Its self-releasing feature enables screw pulls and material removal from the metal surface while scrubbing and pressurising agents allow the purge to reach stagnation points in the processing unit. The material is suitable for use with all resins over the temperature range from 135–232°C (275–450°F). Dyna-Purge also offers advice for compounders looking for more effective extruder purging. “One common challenge with both single and twin-screw extrusion is low pressure processing,” says Ropach. “Utilising a CPC that is free of fillers allows the screen pack and/or breaker plate to be left in place. This enables the processor to build ad- equate back pressure within the screw and barrel to improve purging outcomes. The screw can be started slowly and gradually increased to the maximum, safe revolutions per minute. In addition, utilising the ‘disco’ purge method – variable RPM – may also improve results.”
Trials carried out at Germany’s Kunststoff-Zentrum Leipzig compared performance of Völpker’s Cevo-clean J-1819 against a commercially- available competitor in a coloured transparent PMMA application. Figure 1 (upper image) compares the two purging compounds against cleaning with no purging agent; Figure 2 (lower image) shows injection moulded plaques produced on the first and 26th shots after the two purging compound cleans Source: Völpker/Kunststoff-Zentrum Leipzig
— less product needed. It was also engineered to enable the purge to be reground and reincorpo- rated safely for processing or for resale as purges, making it a far more versatile product with even more value to the processor,” she says. Dyna-Purge says its Leading Technology line of
purging compounds incorporates seven grades that have been optimised and re-developed for these specific industry needs. New products suitable for compounding use include Dyna-Purge L, which is a high-performance, grade incorporating the company’s 3X technology and is said to act on the process boundary layers, as well as negative flow and stagnation points. Its formula allows it to remove resin, colour, carbon, additives and impurities without abrasives or chemi- cals. It is suitable for use with all types of resins over
56 COMPOUNDING WORLD | September 2021
Simplified solutions There are many purging and cleaning products on the market that act through different mechanisms and sometimes require complex handling steps and/or the use of high volumes of material, according to Völpker Spezialprodukte (best known as a producer of process waxes). “For example, there are products on the market that have a cleaning effect via chemical reactions,” says Dr Lutz Matthies, Head of Business Development. “We see disadvantages in this approach because of the relatively high effort required in terms of handling and time needed with respect to the effect achieved. The user wants a good, cost-effec- tive material that can be used for the majority of cleaning tasks with minimal expenditure of time and material. We have used this as a guide for the development of our new product.” The company recently moved into the purging compound sector with its Cevo-clean J-1819 purging concentrate. “As a long-established wax producer, Völpker has significantly expanded its plastics additives business in recent years,” says Matthies. “Due to their unique properties, Völpker wax additives are used as multi-functional high- performance additives in the plastics industry, as well as recycling. They serve, among other things, as viscosity-regulating combination lubricants and dispersion aids, especially if special quality requirements have to be met.” With a customer base of plastics processors, compounders and masterbatch manufacturers,
www.compoundingworld.com
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100
