ADDITIVES | PROCESS AIDS/LUBRICANTS
Above: Völpker produces a broad range of wax processing aids
pigments and additives in masterbatches. Clariant is moving ahead on more develop-
ments. “Additional work on compatibilisation needs to be done to further the efforts towards realising a circular economy, via re-use and recycling of often impure materials,” says Neuber. “Functional waxes and polymers can certainly help this area. Also, more nucleation development with lubricating and processing aids can surely help reduce energy consumption and make for better quality finished goods for work, home and transportation.”
System performance Montan wax producer Völpker Spezialprodukte markets its products as Waradur and Cevo, which is a more recent introduction. Its main development emphasis is on improving sustainability through improved system performance of its products, but it is also working on bio-based grades. Looking first at the performance work, Business Development Leader Dr Lutz Matthies says the company recently carried out investigations into how these products can affect the distribution of carbon fibres in polypropylene. It has also shown that significantly reduced cycle times can be achieved in injection moulding of PA66. Matthies says use of one of its waxes, Waradur E (an ester wax consisting of montanic acids with ethylene glycol), enabled a compounder of carbon fibre-reinforced polypropylene com- pounds for electrical and electronic applications
to reduce expenditure on raw materials. When using 0.5% Waradur E in a compound containing 8% carbon fibre, a reduction in electrical resist- ance (ohm) and specific electrical resistance (ohm. mm²/m) in the range of two orders of magnitude was measured (Table 1). “Waradur E causes a very good distribution and alignment of the individual fibres, so that the conductivity is significantly improved, which mani- fests itself in a drop in resistance values,” says Matthies. “This significantly-improved carbon fibre distribution ultimately leads to a reduction in the cost of raw materials, for example up to 50% less carbon fibre usage with about the same conductivity.” In investigations into the protection and distribu-
tion of flame retardants in compounds, Völpker was able to overcome a problem for a compounder of a glass reinforced FR grade of PA66 that was unable to efficiently mould the compound without strong foaming. The FR additive was being partially degraded as a result of the high shear forces that occurred during processing, with the acid that was produced initiating degradation of the polyamide resin. “The use of Waradur OP (0.3%) instead of calcium stearate reduced the shear stress of the melt to such an extent that foaming did not occur,” says Matthies. “The compound could be produced without problems while maintaining the required fire classification V0 (UL94).” Waradur OP consists of esters of montanic acids with multi-hydroxyl alcohols; it also contains calcium montanate.
Specialised solutions Völpker’s Cevo waxes enable the innovation potential of specialised waxes to be fully exploited, according to Matthies. “Cevo additives can be used to solve processing and application-related issues,” he says. He highlights aspects such as material distribution, fast injection, filling long flow paths, the avoidance of friction peaks, fast demoulding, and process stabilisation of the compound. “These wax additives perform very specific
tasks,” Matthies says. He cites the example of a compounder that was using re-milled and agglom-
Table 1: Data showing a significant reduction of electrical resistance in carbon fibre reinforced PP through the use of Waradur E and OP montan waxes as dispersing agents
PP +8.0 % carbon fibre Electrical resistance [Ω]
Specific electrical resistance [Ω mm2 Source: Völpker Spezialprodukte
44 /m] COMPOUNDING WORLD | April 2020
2.5 x 104 1.2 x 107
PP + 8.0% CF
+ 0.5% Waradur E 4.5 x 102 2.0 x 105
PP + 8.0% CF
+ 0.5% Waradur OP 4.2 x 102 2.0 x 105
www.compoundingworld.com
IMAGE: VÖLPKER
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