ADVERTISEMENT FEATURE
Processing aid for production of HFFR composites
To learn more about VISCOSPEED and its applications visit
www.viscospeed.com
by
A new way to handle cable industry EVA shortages
Since the end of 2020, the prices of polymers — and especially EVA copolymers — has been following a consistent upward direction. While comparing the price development of polyolefin elastomers (POE) and EVA polymers, one notes a rather stable price level for POEs since April 2021, whereas EVA has been rising to new all-time highs. Therefore, we at Innospec expect current and long-term price advantages for POE-based formulations that can provide a suitable alternative for many polymeric cable compounds. As a showcase example, we have explored their use in CPR-compliant (EU Construction Products Regulation) HFFR (Halogen Free Flame Retardant) sheathing compounds, which typically contain 20% or more of EVA copolymer. For the trials we used a standard
formulation with a 28% vinyl acetate content EVA copolymer (MFI = 3) as the base polymer and an LLDPE (MFI = 3.5) as a property improver. Besides the additives, the standard flame-retardant system contained a mixture of precipitated ATH and natural milled MDH (See Table 1, Formulation EVA). In the study, the EVA copolymer was
replaced by POE and different VISCOSPEED products. The test formulations included the new development VISCOSPEED HP (high polarity), resulting in better properties during fire tests (Table 2, Formulation POE 2) and VISCOSPEED HP-X (developmental), allowing for the use of simple uncoated natural milled MDH (Table 2, Formulation POE 3). The previously- mentioned replacement yielded a minimum 16% decrease in cost and an improvement in mechanical properties and flowability (Table 2, Formulation POE 1). To fully assess cost optimisation
potential, a complete replacement of price- increasing precipitated ATH with natural MDH was included to yield a 30 % decrease in the total compound cost. As has been reported in many scientific papers and patents, the full replacement of pp-ATH with n-MDH is only possible with a POE- based polymeric matrix. Polarity and low molecular weight, in synergy with maleated
Table 1: Comparison of different EVA and POE-based cable compound formulations with basic mechanical properties and system cost
FORMULATIONS EVA28 MFI 3 POE MFI 1.5
mLLDPE MFI 3.5 VISCOSPEED
VISCOSPEED HP
VISCOSPEED HP-X (dev) LLDPE-g-MAH
Silicone MB, Stabiliser Fine precipated ATH Fine milled MDH Coated CaCO3 Cost advantage PROPERTIES MFI @ 190°C TS (MPa) EB (%)
EVA 23.5 -
8 - - -
4
1.5 45 12 6 -
EVA 5.4
14.3 145
POE 1 -
21.5 8 2 - -
4
1.5 45 12 6
-16%
POE 1 7.3
15.8 212
POE 2 -
20 7 -
3 -
3.5 1.5 45 20 -
-16%
POE 2 5.4
13.4 180
POE 3 -
22.5 7 - -
3 3
2.5 -
62 -
-30%
POE 3 5.4
11.3 158
Table 2: Vertical fire test results for different EVA and POE-based cable compound formulations (according to DIN 4102)
Vertical fire test Burning drops Flame width
Total burning rating
EVA NO 2.5 6
coupling agents, is the reason for the efficiency of VISCOSPEED as an active ingredient at the POE/fillers interface. CPR-complaint cables need to fulfil
required flame-retardant measures through fire tests. As the industry standard, EVA- based compounds work well in vertical fire tests and they also yielded the highest rate in this study. Nonetheless, when using the VISCOSPEED products the big issue of burning droplets can be eliminated while using the POE-polymer as the base component (Table 2, Formulation POE 1-3). Further optimising the standard
formulation and increasing the filler content, possible due to the VISCOSPEED dosage, helped increase the internal burning rate, preparing the POE
POE 1 NO 5.5 3.5
POE 2 NO 3
4.5
POE 3 NO 6
3.5
formulation for CPR-compliance (Table 2, Formulation POE 2). In summary, it can be seen that, with the help of the VISCOSPEED product line, a POE-based formulation can be fine-tuned to eliminate the presence of burning droplets and to allow the flame retardant filler content to be raised to a higher level. This can make the final formulation suitable for CPR-compliance. The exchange of EVA for POE allowed for a strong increase in elongation at break (Table 1, Formulation POE 2) and decreased the total compound cost by up to 30 % (Table 1, Formulation POE 3). In sight of the ongoing crisis in EVA copolymer availability, this approach can be considered as a timely next step in the evolution of CPR compliant cables.
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
