Ref: 04/2014. Robac SRM102. New Accelerator for Polychloroprene (CR)

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Amber Patrick
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1 Ref: 4/4 Robac SRM New for Polychloroprene (CR)

2 Contents. Introduction to Robac SRM. Benefits of Robac SRM. General Purpose Polychloroprene Masterbatch 4 4. s 4. Rheological Properties.. Mooney Viscosity and Mooney Scorch.. Moving Die Rheometer 6. Mechanical Properties 6 7. Heat Ageing Results 7 8. Compression Set 7 9. Variable Temperature Curing Moving Die Rheology Mechanical Properties 8. Performance of Robac SRM at a Reduced Zinc Oxide Level 9.. s 9.. Rheological Properties 9... Mooney Viscosity and Mooney Scorch 9... Moving Die Rheometer.. Mechanical Properties.4. Heat Ageing Results.. Compression Set. Conclusions

3 . Introduction to Robac SRM Due to the classification of ethylene thiourea () as a reprotoxin (CMR B) and its recent inclusion on the candidate list of substances of very high concern (SVHC), a replacement for in polychloroprene has been required for many years. From a culmination of years research and through support via the European Community FP7 framework program under the title SafeRubber Project, the new accelerator Robac SRM has been developed as a safe and highly effective replacement for in polychloroprene. In industrial validation trials as part of the SafeRubber project, Robac SRM has been tested in both extrusion and compression moulding applications in five different factories in three EU countries and the resultant compounds have been shown to perform as well as. This technical brochure provides representative data for the application of Robac SRM in a commercial general purpose grade polychloroprene masterbatch. Rheology and physical property data, as well as heat ageing data along with compression set are provided. The results show that CR compounds cured with SRM meet the British Standards BS7 specification. Robac SRM behaves as a multi-functional accelerator and data contained herein shows that the loading of ZnO can be reduced in the CR formulation without affecting the physical properties of the vulcanisates Robac SRM currently has a pending UK priority patent application covering SRM itself, its manufacture and its uses. Benefits of Robac SRM Safe alternative to in polychloroprene Better performance than other commercially available alternatives to currently on the market (chemical names) Functions at a reduced zinc oxide loading to give equivalent performance to cured systems Synergises with other conventional accelerators Capable of crosslinking speciality polymers (ECO, AEM) as well as diene polymers (NR, SBR, EPDM) Commercially available as Robac SRM PM Competitively priced

4 . General Purpose Polychloroprene Masterbatch General Purpose CR Masterbatch (MB8*) Ingredient phr Polychloroprene** Process Aid A. Antioxidant A Antiozonant Antioxidant C Stearic Acid Factice MgO (8%) Carbon Black A 4 Carbon Black B Plasticizer A Total. *Supplier: Clwyd Compounders ** Denka S4V equivalent to Neoprene WRT Typical applications: Suitable for a wide range of applications including hoses and seals 4. s All formulations contain phr zinc oxide (ZnO), which is traditionally the standard level of ZnO used in CR cure systems. Additionally, although the accelerators used were in PM form levels quoted are the level of active ingredient present... ZnO (% active weight) (% active weight) - Robac SRM (% active weight) -. General Purpose CR Masterbatch 4

5 . Rheological Properties.. Mooney Viscosity and Mooney Scorch Conditions: Samples stored at 4 C and tested at C Mooney Viscosity Mooney Scorch (T/min) SRM Initial : 4:4 Week :4 7:6 Week :9 6: () Week 9: : (SRM) Week 4 8: :9 ML +4 (MU) Weeks at 4 C Mooney viscosity of CR masterbatch containing Robac SRM is stable over 4 weeks.. Moving Die Rheometer Test Conditions: 6ºC for 6 min SRM ML (lb.in).77.8 MH (lb.in) TS (min) : :8 T9 (min) :7 : 6..8 Cure Rate (lb.in/min) MH, scorch time and T9 for SRM containing formulations are similar to those cured with

6 6. Mechanical Properties Conditions: Press cure at 7ºC for min Elongation at Break Ultimate Tensile Strength Elongation at Break (%) Ultimate Tensile Strength (MPa) () (SRM) (SRM) SRM Tensile Strength (MPa).. > Elongation at Break (%) > Hardness (IRHD) () Target BS 7 Specification CR cured with SRM give vulcanisates with tensile properties comparable to those cured with SRM cured CR meets tensile properties of the British Standard BS7 specification 6

7 7. Heat Ageing Results Test Conditions: Cured 7ºC for min and tested after 7 Days at 7ºC Ultimate Tensile Strength Before Ageing After Ageing Elongation at Break (%) Ultimate Tensile Strength (MPa) () () (SRM) (SRM) SRM 7 (+) 77 (+) +7 Tensile Strength, MPa (% change) 7. (+%) 4. (-%) - % Elongation at Break, % (% change) 8 (-%) 9 (-%) - % Hardness, IRHD (unit change) Elongation at Break Before Ageing After Ageing Target BS 7 Specification Tensile properties of SRM cured CR meet the British Standard BS7 after thermal heat ageing 8. Compression Set Conditions: 4 hours at 7ºC Compression set of SRM cured CR compounds meet the British Standard BS7 (max %) specification Compression Set (%) () 7 (SRM)

8 9. Variable Temperature Curing SRM is an effective curative at a range of temperatures 9.. Moving Die Rheology Test Conditions: MDR at ºC, 6ºC and 8ºC Rheometer C/6min 6 C/6min 8 C/6min ML (lb.in)..8.4 MH (lb.in) T (min).94 :8.4 T9 (min) 9.7 :. Cure Rate (lb.in/min) Mechanical Properties Test Conditions: Press cure for min at ºC, 7ºC and 8ºC Press Cure C/min 7 C/min 8 C/min Tensile Strength (MPa) Elongation at Break (%) 6 Hardness (IRHD) 8

9 . Performance of Robac SRM at a Reduced Zinc Oxide Level Traditionally, phr ZnO is used as part of the accelerator system in CR. Heavy metal contamination in the environment is hazardous and therefore a general reduction of the level of ZnO used in the industry is desirable. Robac SRM behaves as a multi-functional accelerator and can be used with lower levels of ZnO without affecting physical properties of the vulcanisates.. s Although all accelerators used were in PM form levels quoted are the level of active ingredient present.... ZnO (% active weight) (% active weight) - - Robac SRM (% active weight) -.. General Purpose CR Masterbatch.. Rheological Properties... Mooney Viscosity and Mooney Scorch Conditions: Samples stored at 4 C and tested at C Mooney Viscosity Mooney Scorch (T/min) ML +4 (MU) 8 SRM SRM ZnO Initial : 4:4 :9 () Week :4 7:6 6:44 (SRM) Week :9 6: 6: (SRM phr ZnO) Week 9: : 6: Week 4 8: :9 : Weeks at 4 C Mooney viscosity of CR masterbatch containing SRM and a lower loading (phr vs standard phr) of ZnO is stable over 4 weeks 9

10 ... Moving Die Rheometer Test conditions: Press cure at 6ºC for 6 min SRM SRM ML (lb.in) MH (lb.in) TS (min) : :8 : T9 (min) :7 : 9: ZnO Cure Rate (lb.in/min) In formulation with a lower ZnO content (phr vs phr), T9 is lower and therefore cure time is reduced significantly. Marching modulus observed in CR cured with phr ZnO is reduced with a lower level of ZnO which creates a flatter state of cure... Mechanical Properties Conditions: Press cure at 7ºC for min SRM SRM ZnO Hardness (IRHD) Tensile Strength (MPa)... > Elongation at Break (%) 8 > Target BS 7 Specification

11 Ultimate Tensile Strength Elongation at Break Elongation at break (%) Ultimate Tensile Strength (MPa) () (SRM) (SRM phr ZnO) () (SRM) (SRM phr ZnO) Physical properties of CR cured with SRM containing a lower ZnO level (phr) are similar to those of with a standard ZnO (phr) loading. Physical properties meet the British Standard BS7 specification.4. Heat Ageing Results Test conditions: Press cure 7ºC for min and tested after 7 days at 7ºC Elongation at Break Ultimate Tensile Strength Before Ageing After Ageing Elongation at Break (%) Tensile Strength (MPa) After Ageing () (SRM) () (SRM phr ZnO) (SRM) (SRM phr ZnO) SRM SRM 7 (+) 77 (+) 78 (+) +7 max ZnO Hardness, IRHD (unit change) Before Ageing Target BS 7 Specification Tensile Strength, MPa (% change) 7. (+%) 4. (-%).6 (+%) -% max Elongation at Break, % (% change) 8 (-%) (-6%) - % max 9 (-%) Tensile properties of CR vulcanisates cured with SRM and a lower ZnO level (phr) meets the British Standard BS7 specification after thermal heat ageing

12 .. Compression Set Conditions: 4 hours at 7ºC Compression set of SRM containing CR formulations with lower ZnO (phr) content meets the British Standard BS7 (max %) Compression Set (%) () (SRM) (SRM phr ZnO). Conclusions Rheology and physical data, as well as heat ageing data contained in this technical brochure show that vulcanisates cured with Robac SRM give properties comparable to those cured with. All properties of Robac SRM-cured polychloroprene meet the British Standard BS7 specification. The results clearly indicate that Robac SRM is a viable replacement for in curing polychloroprene rubber. Additionally, it is possible to reduce the zinc oxide levels in a Robac SRM cure system without affecting the physical or rheological properties of the final vulcanisate.

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