in Peroxide Cured EPDM Cable

Transcription

1 Non-black Fillers in Peroxide Cured EPDM Cable Insulation Compounds Authorship: Translation: Karin Müller Dr. Horst E. Toussaint Approval: May 2018 VM-/ / VM / Dr. Alexander Risch HOFFMANN MINERAL GmbH P.O. Box 1 60 D-866 Neuburg (Donau) Phone (9-8 1) 5-0 Fax (9-8 1) 5-0 Internet: info@hoffmann-mineral.com

2 Content Abstract 1 Introduction 2 Experimental 2.1 Compound formulations 2.2 Compounding and Curing 2. Garvey Extrusion 2. Volume resistivity Results.1 Mooney viscosity and Mooney scorch.2 Curing properties. Garvey Extrusion. Mechanical properties.5 Volume resistivity.6 Properties after aging in hot air.7 Compound raw material cost indices Summary.1 Appendix Seite 1

3 ABSTRACT Among the untreated fillers, the American hard came off, straight or in the with, as the weakest filler. The English calcined and, when used straight, give very similar results to each other, however, in the with, proved superior. Including cost considerations, results as the best suited filler. When looking at the total property profile of the two surface treated fillers, has to be confirmed on equal level with the calcined. Including cost considerations, Aktisil VM 56 must be judged the best suited product in this comparison. Summary at a Glance Summary At a Glance Incorporation American hard straight - 0 untreated English calcined SILLITIN Z 86 surface treated surface treated American AKTISIL VM 56 calcined with Processing (Extrusion) 0 -- Cure behavior Mechanical properties Hot air aging Electrical properties dry 0 - After water immersion Cost Total assessment - 0 = very good; = good; 0 = satisfactory; - = poor; -- = very poor Table 1 Seite 2

4 1 Introduction Cable insulation compounds are subject to many different requirements, as for instance listed in DIN VDE 0207 Part 20 EI. The profile required includes good mechanical properties, excellent extrusion characteristics as well as high electrical resistivity also after water immersion. Required properties taken from parts of this standard: Tensile strength Elongation at break Volume resistivity 1) Before Aging > 5.0 MPa > 200 % > W x cm After hot air aging 168 h / 100 C >.2 MPa < /- 25 % Change > 200 % < /- 25 % Change 1 ) Only valid for national constuctions Properties were also studied which are not included in cable standards, but which how-ever give the compounder valuable indications about the processing properties and the quality of the final product. The test program included potentially suitable fillers for this application, as summarized in Table. Also s with, as common in the industry, were considered in appropriate variations (see Table 2). Seite

5 2 Experimental 2.1 Compound formulations Base Formulation EPDM 70 Shore A phr Buna AP 258 (Buna EP G 96) Stearic acid Zinkoxyd aktiv Paraffin 5/ Filler Whiting Sunpar Vulkanox HS/LG Vulkanox MB/MG TAC GR 50 % Perkadox 1/0 pd Total Table 2 The raw materials used were the following: Buna AP 258 (Buna EP G 96): crystalline, medium green strength ML (1) 125 C: ENB-Content: 10 % Ethylene content corrected: 66 %-Gew. Ethylene content uncorrected: 7 %-Gew. Oil type: paraffinic Oil content: 0 phr Zinc oxide Processing aid Paraffin wax Paraffinic mineral oil 2.2.-Trimethyl-1.2-dihydroquinoline (TMQ) 2-Mercapto-benzimidazole (MBI) Zinkoxyd aktiv: Stearic acid : Paraffin 5/56: Sunpar 2280: Vulkanox HS/LG: Vulkanox MB/MG: TAC GR 50 %: Triallylcyanurate (50 %) Perkadox 1/0 pd: Bis(tert-butylperoxyisopropyl)benzene (0 %) Seite

6 Fillers Selected Characteristics Particle size [µm] d 50 d 97 Oil Absorption [g/100g] Specific Surface area BET [m²/g] Surface treatment American hard none English calcined none none Surface treated American calcined Vinyl silane Vinyl silane Whiting none Table Appropriate EPDM compounds are made up with fillers which can markedly affect the processing and final performance properties. The American hard has the highest BET surface area and a high particle size d97. by comparison offers a markedly lower BET surface area and lower figures for the particle size distribution along with a slightly higher oil absorption. As different from the untreated fillers, and the surface treated American calcined have been subject to a surface treatment with vinylsilane (Table ). Seite 5

7 2.2 Compounding and Curing Preparation and Curing of the Compound Preparation Open mill Ø 150 x 00 mm Batch volume: approx. 500 cm³ Temperature: 60 C Mixing cycle: approx. 25 min. Curing Press, 180 C, t % Fig. 1 All compounds were mixed on a laboratory roll mill (Ø 150 x 00 mm) at 20 rpm with a batch size of about 500 cm. The mixing time was adjusted according to the incorporation characteristics of the fillers, and each time registered. The curing time was always t90 10 % at 180 C in an electrically heated press (Fig. 1). Seite 6

8 2. Extrusion Extrusion According to ASTM D 220 Schwabenthan - Extruder Polytest 0R D = 0 mm, L/D-Ratio = 15 Temperature: 70 / 70 / 110 C Variations: Constant screw speed 50 rpm Constant output rate 1 m/min Garvey extrusion rating: First digit: Die swell Third digit: Surface appearance Assessment 1 = poor to = very good Fig. 2 Garvey extrusion tests were carried out in accordance with ASTM D220. For assessing the extrusion characteristics of the compounds just the first and the third digit in Method A were used, because these are most relevant for cable extrusions. In fact, these digits reflect the die swell (first digit) and the surface quality (third digit) of the profiles. The tests with a screw speed of 50 rpm served for the determination of the throughput and the corresponding extrudate quality. By contrast, at constant output rate only the surface quality can be assessed (Fig. 2). Seite 7

9 2. Volume Resistivity Volume Resistivity DIN IEC 9 Test outline: Dimension of plates: 10 x 10 cm Thickness of plates: about 2 mm Electrical relaxation: 2 h / 70 C Electrode set-up: circular plate electrode with protective ring Test method: Voltage/Amperage method Test voltage: > Ωxcm: 500 V; < Ωxcm: 100 V Recording time: 1 min. after application of voltage Test temperature: 2 C Water immersion: 7 / 1 / 28 days at 70 C in deionized water Evaluation: ρ = R X * A / h with ρ resistivity in Ωxcm R X volume resistance in Ω A effective surface area of the protected electrode (2 cm²) h median thickness of the test plate in cm Fig. All important test parameters are listed in Fig.. The water immersion test, while not part of the cable standard, helps towards a better differentiation of the fillers (Fig. ). Seite 8

10 Results.1 Mooney viscosity and Mooney scorch Mooney Viscosity DIN 5 52 Part, ML C Filler straight Mooney units Blend with Americ. hard Fig. gives a lower Mooney viscosity compared to the other non-treated fillers. The surface treated fillers lead to a lower viscosity compared with the untreated pro-ducts, and hardly differs from the surface treated American calcined. In s with, the Mooney viscosity will be markedly decreased, while the differences between the fillers are also minimized (Fig. ). Seite 9

11 Mooney Scorch DIN 5 52 Part, ML C min. Americ. hard Filler straight Blend with Fig. 5 Mooney scorch time as an index of onset of cure during processing only changes moderately with the different fillers. comes out at the same level with the hard, while the calcined reaches somewhat higher figures. The surface treated grades attain directionally slightly longer scorch times. In the s with, the scorch time generally comes off markedly longer, with this effect particularly pronounced with the non-treated fillers (Fig. 5). Seite 10

12 .2 Curing properties Conversion Time t 5 DIN A, Frank Linear Shear Vulcameter, 180 C Filler straight min. Blend with 0,0 0,2 0, 0,6 0,8 1,0 1,2 1, 1,6 Americ. hard Fig. 6 Conversion Time t 90 DIN A, Frank Linear Shear Vulcameter, 180 C min. Americ. hard Filler straight Blend with Fig. 7 and generate the shortest conversion times t90, which indicates the required curing time, coupled with a long conversion time t5. The surface treated calcined offers a similarly long conversion time t5, but needs a longer time to full cure. The American hard straight also gives a short conversion time t90, but also a shorter t5. In the with the cure time, however, comes out definitely longer. The calcined without surface treatment requires very long cure times (Figs. 6 and 7). Seite 11

13 . Extrusion Garvey Extrusion 50 rpm Filler Straight Americ. hard Garvey Rating Die swell Surface Output 6 cm/min. 22 cm/min. 2 cm/min. Surface treated Americ. calc. 258 cm/min. 28 cm/min. Fig. 8 and, along with the calcined s, lead to excellent profile surface appearance as well as a high throughput. The American hard offers a still higher output, but at the cost of a much poorer surface quality. Also the die swell is higher (Fig. 8). Garvey Extrusion 50 rpm Blend with Whiting Americ. hard Garvey Rating Die swell Surface Output 10 cm/min cm/min. 280 cm/min. Surface treated Americ. calc. 268 cm/min. 256 cm/min. Fig. 9 In with, and give a high output rate along with good surface appearance. Only the surface treated calcined reaches the same level, while this grade without treatment brings about higher die swell and a rough surface. With the exception of the hard, the output of the s with generally is somewhat increased (Fig. 9). Seite 12

14 Garvey Extrusion 1 m/min. Filler Straight Garvey Rating Die swell Surface Americ. hard Fig. 10 At a constant output rate of 1 m/min similar conditions are found as for the extrusion at 50 rpm. The calcined s and the two Neuburg Siliceous Earth grades lead to attractive surfaces and low die swell. Only the hard disappoints with a rough surface (Fig. 10). Garvey Extrusion 1 m/min. Blend with Whiting Garvey Rating Die swell Surface Americ. hard Fig. 11 The s with obey the same assessment as at 50 rpm. and Aktisil VM 56, along with the surface treated calcined, offer the best results. The hard, once again, comes out last with the lowest results (Fig. 11). Seite 1

15 . Mechanical properties Tensile Strength DIN 5 50, S2 MPa Americ. hard Filler straight Blend with Fig. 12 imparts the highest tensile strength of the non-treated fillers. This level remains valid also in the with, while the hard here suffers from a decrease. reaches the highest tensile strength of all the fillers tested, including the surface treated. In the s with, however, the tensile strength with surface treated fillers tends to decrease, but in particular the combination with Aktisil VM 56 still remains well above the straight non-treated grades (Fig. 12). Seite 1

16 Elongation at Break DIN 5 50, S2 % Americ. hard Filler straight Blend with Fig. 1 Among the non-treated fillers, comes off comparable with the calcined, while the hard shows much lower figures. The combination with for all nontreated fillers results in a similar increase of the elongation. The surface treated fillers straight only lead to relatively low elongations at break, which however can be improved by additions of. Another way to achieve this is the reduction of the peroxide concentration, which also has positive effects on the cost side (Fig. 1). Seite 15

17 Modulus 100 % DIN 5 50, S2 MPa Americ. hard Filler straight Blend with Fig. 1 Differences are only observed between the two groups without respectively with surface treatment, but there is an increase by the factor of two. In the s with, the modulus generally is decreased, so that with the surface treated fillers similar levels come out as with the straight non-treated grades. Moduli along with compression set figures should indicate a correlation with the hot set as well as with the high temperature pressure resistance. The higher the modulus in combination with a low compression set, the better characteristics should result. The surface treated grades including meet such a property profile in an excellent way (Fig. 1). Seite 16

18 Tear Resistance DIN A, F max, 500 mm / min. N / mm Americ. hard Filler straight Blend with Fig. 15 Among the fillers without surface treatment, arrives at a slightly higher tear strength compared with the calcined, while the hard offers by far the highest level of all fillers tested. Combinations with, by contrast, give lower figures throughout. The surface treated grades attain only lowish tear strength levels, which are not further modified by ing with (Fig. 15). Seite 17

19 Compression Set DIN I, 2 h / 100 C % Americ. hard Filler straight Blend with Fig. 16 The hard by far imparts the highest compression set of all fillers tested, but the figures are improved by ing with. Otherwise within the groups without respectively with surface treatment hardly any significant differences can be observed. Blending with hardly affects the compression set results or not at all, while with the surface treated fillers similar results are obtained as with the straight non-treated grades. In line with the low compression set along with high moduli the hot set test as well as the high temperature compression resistance should be optimum with the surface treated fillers (Fig. 16). Seite 18

20 .5 Volume resistivity Volume Resistivity Filler Straight Immersion in Deionized Water at 70 C Ohm x cm 1,00E18 1,00E16 1,00E1 1,00E12 1,00E10 1,00E08 1,00E06 1,00E0 1,00E02 1,00E Immersion time in days American hard English calcined Surface treated Americ. calc. Fig. 17 In the DIN VDE 0207 standard Part 20 no requirements are listed with regard to the electrical resistance after immersion in water, but this test allows an assessment of the emergency properties of a cable insulation. In order to ensure a sufficiently high resistivity also after water immersion, the use of a surface treated grade such as must be recommended, as there exists only a minimum initial change of the resistivity which then remains on a stable high level. The volume resistivity with the non-treated fillers dramatically goes down during immersion in water, and this without reaching a stable final level (Fig. 17). Volume Resistivity Blend with Whiting Immersion in Deionized Water at 70 C Ohm x cm 1,00E18 1,00E16 1,00E1 1,00E12 1,00E10 1,00E08 1,00E06 1,00E0 1,00E02 American hard English calcined Surface treated Americ. Calc. Fig. 18 1,00E Immersion time in days The combination with results in an improvement of the figures for the non-treated fillers, but the excellent high level of the surface treated grades will still not be matched (Fig. 18). Seite 19

21 .6 Hot air aging 168 h / 100 C Hot Air Aging Change of Hardness 168 h / 100 C Filler straight Shore A Blend with Americ. hard Fig. 19 Within the group without but also with surface treatment, excepting the hard hardly any significant differences can be observed. The combination with also shows no mentionable effects (Fig. 19). Hot Air Aging Change of Tensile Strength 168 h / 100 C Filler straight % Blend with Americ. hard Fig. 20 Similar to the situation for hardness, within the groups without respectivly with surface treatment, and with the exception of the hard and the calcined /, there are hardly any significant differences to be found. The combination with does not significantly affect the results (Fig. 20). Seite 20

22 Hot Air Aging Change of Elongation at B. 168 h / 100 C Filler straight %, rel. Blend with Americ. hard Fig. 21 The hard shows the largest change of elongation at break of all the fillers tested, followed by. Combinations with give only little changes. The surface treated fillers straight respectively in s with lead to comparable level of elongation change (Fig. 21)..7 Compound raw material cost indices Compound Raw Material Cost Indices Germany 2009, = 100, Volume Related Americ. hard Filler straight Blend with Fig. 22 The costs of the compound with was deliberately set at 100 index points. The hard compound comes off comparably, while the calcined calls for higher expenses. Still more pronounced is the difference towards the surface treated fillers, where the treated version of the calcined brings about the highest compound costs. Aktisil VM 56 in comparison is situated clearly lower, and in the with is able to even go below the costs of the non-treated calcined (Fig. 22). Seite 21

23 Summary Summary Untreated Fillers American hard, straight as well as in with, comes out very unsatisfactory in mixing and processing, leads to high compression set, high tear strength, low volume resistance, poor extrusions and high changes of properties upon aging. English calcined is easy to mix and process, gives very good compression set, good extrusion properties, but suffers from a sharp decrease of the volume resistance upon water immersion. too is easy to mix and process and largely comes close to the calcined. With respect to extrusion, however, is markedly superior, in particular in the with. Also cost aspects should speak for the Neuburg Siliceous Earth grade. Fig. 2 Summary Surface Treated Fillers Surface treated American calcined provides a very good property profile with respect to incorporation, processing, mechanical and electrical properties as well as extrusion characteristics. However, the costs here present themselves very high. too comes off with a very good property profile which regard to incorporation, processing, mechanical and electrical properties as well as extrusion characteristics. The price/performance ratio without doubt speaks in favor of. Fig. 2 Seite 22

24 Summary Among the untreated fillers, the American hard came off, straight or in the with, as the weakest filler. The English calcined and Sillitin Z 86, when used straight, give very similar results to each other, however, in the with, proved superior. Including cost considerations, results as the best suited filler. When looking at the total property profile of the two surface treated fillers, Aktisil VM 56 has to be confirmed on equal level with the calcined. Including cost considerations, must be judged the best suited product in this comparison. Fig Appendix Results Raw Compound Properties M. 2 American hard straight untreated English calcined SILLITIN Z 86 surface treated surface treated American AKTISIL VM 56 calcined with Mixing time min Mooney viscosity DIN 5 52, Part ML (1), 120 C Mooney scorch DIN 5 52, Part ML 5, 120 C ME min Linear shear vulcameter (Frank) DIN 5 529, A 180 C t min. 5 t min. 90 t % (Cure time) min Fig. 26 Seite 2

25 Fig. 27 Results Cured Rubber Properties M. 2 American hard straight untreated English calcined surface treated surface treated SILLITIN Z 86 American AKTISIL VM 56 calcined with Hardness Shore DIN 5505-A A Tensile strength DIN 5 50, S2 MPa Modulus 100 % DIN 5 50, S2 MPa Modulus 00 % DIN 5 50, S2 MPa Elongation at break DIN 5 50, S2 % Rebound DIN % Tear resistance DIN A, Fmax N/mm mm/min Compression set DIN I % h/100 C Density DIN 5 79 g/cm³ Results Extrusion ASTM D 220 M. 2 American hard straight untreated English calcined SILLITIN Z 86 surface treated American calcined surface treated AKTISIL VM 56 with Output rate 1m/min Rating Torque Nm Screw speed 50 rpm Rating Output Torque cm/min. g/min. Nm Fig. 28 Seite 2

26 Results Volume Resistivity, DIN IEC 9 M. 2 American hard straight untreated English calcined SILLITIN Z 86 surface treated American calcined surface treated AKTISIL VM 56 with unaged Ωcm 5.6x.1x 1.7x 1.x 2.x.9x 8.0x 9.x 5.0x.6x after aging in deionized water at 70 C 7 days Ωcm 1.x 2.1x 1.2x 7.2x 2.5x.2x 6.6x.x 6.x 9.8x days Ωcm 5.9x 1.1x.8x 1.2x 6.x 1.5x 1.1x 8.0x 9.6x 8.7x days Ωcm 1.2x.x.2x 1.x 2.9x.1x.1x 1.8x.5x 5.2x Fig. 29 Results Properties after Aging in Hot Air 168 h / 100 C M. 2 American hard straight untreated English calcined SILLITIN Z 86 surface treated American calcined surface treated AKTISIL VM 56 with Hardness Change Shore A Shore A ± ± Tensile strength Change MPa % Modulus 100 % Change MPa % Elongation at break change % %, rel Fig. 0 Our technical service suggestions and the information contained in this report are based on experience and are made to the best of our knowledge and belief, but must nevertheless be regarded as non-binding advice subject to no guarantee. Working and employment conditions over which we have no control exclude any damage claims arising from the use of our data and recommendations. Furthermore, we cannot assume any responsibility for any patent infringements which might result from the use of our information. Seite 25