Closing the loop: Rubber Recycling. Joint seminar Kumi-instituutti instituutti & MOL

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1 Closing the loop: 1 Rubber Recycling Joint seminar Kumi-instituutti instituutti & MOL

2 Contents 2 - Introduction - Present: Rubber crumb Surface activated rubber crumb Reclaim / devulcanizate - Future

3 Introduction Used tires 3 (V.L. Shulman, 2008, ETRA) Landfill 20% Others 3% 2006 Retreading 12% Export 7% 800,000,000 tires/year Increase: 2%/year Material recycling 27 % Energy recovery 31% EU countries: 2000: ca. 2,700,000 tons 2006: ca. 3,200,000 tons

4 Introduction 4 Legislation ELV: EU legislation End of life vehicles 2015: < 5 % landfill ( End of life vehicles EU legislation, Dir. 2000/53/EC) 2006: Prohibtion of landfill of shredded tires (Dir.1999/31/EC) 2006: < 15% landfill (ELV) 2003: Prohibition of landfill of whole tires (Dir. 1999/31/EC)

2000/53/EC) 2006: Prohibtion of landfill of shredded tires (Dir.

5 Introduction 5 Recycling loops CO 2 + H 2 O + energy C n H m Monomers Polymers Compounds Vulcanized products Energy recovery Increasing Feedstock recovery degree of valorization Material recycling Energy consumption: New rubber: 115 J/kg Rubber granulate: 2 J/kg

Increasing Feedstock recovery degree of valorization Material

6 Rubber powder 6 Vulcanized Granulate Surface activation Rubber rubber Powder Regeneration product Buffings Rubber granulate, 5 mesh = 4 mm Rubber powder, 16 mesh = 1.19 mm Rubber powder, 30 mesh = mm cryogenically ground ambiently ground 10 μm 2 μm

7 Surface activated rubber powder 7 Vulcanized Granulate Surface activation Rubber rubber Powder Regeneration product Biological treatment Granulate Powder Mechanical treatment Physical treatment Chemical treatment Surface activated powder

product Biological treatment Granulate Powder Mechanical

8 Surface activated rubber powder 8 Vulcanized Granulate Surface activation Rubber rubber Powder Regeneration product Biological treatment Granulate Powder Mechanical treatment Physical treatment Chemical treatment Surface activated powder

9 Surface activated rubber powder Chemical treatment 9 Coating: + Polymer Latex, low-molecular liquid polymer, polymer-oil blends + Curing additives Swelling: + Oligomer, evtl. with functional groups + Oil with (curing) additives Grafting: + Silanes + Ethylacrylate

Curing additives Swelling: + Oligomer, evtl.

10 (Surface activated) rubber powder Influence on compound properties 10 System: latex + curing agents Powder: truck treads (70%NR/30%SBR) NR compound SBR compound Tensile strength [MPa] Tear strength [N] Tensile strength [MPa] Tear strength [N] Concentration rubber crumb [%] Concentration rubber crumb [%] Surface activated rubber crumb Untreated rubber crumb Technical Information Rubber Resources

strength [MPa] 20 10 0 Tear strength [N] 50 25 0 0 10 20 30 40 50 - Concentration rubber crumb [%] 0 0 10 20 30 40

11 (Surface activated) rubber powder Influence on compound properties 11 NR compound SBR compound Abrasion [mm 3 ] Abrasion [mm³] Compression set (70º) [%] Rebound resilience (70ºC), [%] 60 0 Compression set (70ºC) [%] Rebound resilience(70º) [%] Concentration rubber crumb [%] Concentration rubber crumb [%] Surface activated rubber crumb Untreated rubber crumb Technical Information Rubber Resources

[%] 100 50 0 Rebound resilience(70º) [%] 50 50 40 40 0 10 20 30 40 50 - Concentration rubber crumb [%] 30 0 10 20 30 40 50

12 Reclaim 12 Vulcanized Granulate Surface activation Rubber rubber Powder Reclaiming product Definition reclaim: A process in which vulcanized rubber is converted into a material which can be blended, processed, and cured again by using mechanical, thermal or chemical processes Devulcanization: Selective scission of sulfur crosslinks Crosslink scission Polymer scission Polymer Crosslinks

processed, and cured again by using mechanical, thermal or chemical processes Devulcanization:

13 Reclaim Processes 13 Mechanical reclaiming Granulate Powder Reclaim Thermal reclaiming Chemical devulcanization

14 Reclaim 14 Thermomechanical breakdown Softeners Polymers mechanical thermal Viscosity decrease 120 C Temperature Thermal: - non-selective in terms of chain length - non-selective for polymer chains and crosslinks - reactive chain ends Molecular weight Initial MWD MWD after thermal breakdown MWD after mechanical breakdown Mechanical: + selective for longer chains - non-selective for polymer chains and crosslinks - reactive chain ends Polymer degradation

chain ends Molecular weight Initial MWD MWD after thermal breakdown MWD after mechanical breakdown Mechanical: +

15 Reclaim Processes 15 Mechanical reclaiming Granulate Powder Reclaim Thermal reclaiming Chemical devulcanization

16 Reclaim Chemical devulcanization aids 16 Radical breakdown - Disulfides Oxidation - Oxygen (air) Nucleophilic breakdown - Mercaptanes - Hydroxydes -Amines Breakdown of C-S bonds - Raney-Nickel - Alkali metals

Nucleophilic breakdown - Mercaptanes - Hydroxydes

17 Reclaim Processes 17 Mechanical reclaiming Granulate Powder Reclaim Thermal reclaiming Chemical devulcanization

18 Reclaim 18 Effect of temperature, reclaiming aid and concentration EPDM roofing sheet compound, EV cured (short crosslinks) 200 C 225 C ( ): HDA CH 3 (CH 2 ) 15 NH 2 ( ): DPDS 250 C 275 C S S ( ): BAFD S S N H N H CO CO Dijkhuis, K., thesis, 2008, ISBN

C ( ): HDA CH 3 (CH 2 ) 15 NH 2 ( ): DPDS 250 C 275 C S S ( ): BAFD

19 Reclaim 19 Effect of temperature, reclaiming aid and concentration EPDM roofing sheet compound: conventionally cured (long crosslinks) 225 C 250 C 275 C ( ): HDA ( ): DPDS ( ): BAFD CH 3 (CH 2 ) 15 NH 2 S S S N H CO S N H CO Dijkhuis, K., thesis, 2008, ISBN

225 C 250 C 275 C ( ): HDA ( ): DPDS ( ): BAFD CH 3 (CH 2 ) 15 NH 2

20 Reclaim 20 Influence on compound properties (EPDM) EPDM roofing sheet compound Conventionally cured ( ): HDA CH 3 (CH 2 ) 15 NH 2 ( ): DPDS S S ( ): BAFD S S N H N H CO CO EV cured Dijkhuis, K., thesis, 2008, ISBN

(CH 2 ) 15 NH 2 ( ): DPDS S S ( ): BAFD S S N H N H CO CO

21 Reclaim 21 Influence on compound properties (NR/SBR) NR/SBR truck tire tread reclaim in a similar compound Reclaiming aid: Diphenyldisulfide Tensile strength [MPa] Tensile strength [MPa] 28 Tear strength [N] Abrasion [mm³] NR/SBR reclaim concentration [phr] Compression set [%] Rebound resilience [%] % relative to basic compound Basic compound (NR/SBR) 22% NR/SBR Reclaim Technical Information Rubber Resources

22 Reclaim 22 (Dis)advantages In a blendwithvirginrubber: + Shorter mixing, milling, extrusion cycles + Lower processing temperature, less scorch + Better tack + Improved temperature resistance + Higher green strength + Easier escape of air from the mold + Improved aging resistance - Influence on property profile

23 Reclaim 23 More efficient devulcanization Influencing factors for reclaiming efficiency: - Temperature - Time - Shearing forces - Devulcanization aid - Restoration of double bonds Shifting to devulcanization: - Low temperatures - Low shearing forces - Appropriate devulcanization aid The right choice of the devulcanization aid is crucial! Dijkhuis, K., thesis, ISBN

24 Rubber Recycling 24 The future 50% of recycled material back into (the original) rubber products Material recycling 50% Landfill 0% Others 3% Retreading 12% Export 7% Energy recovery 28% Shifting the balance between thermomechanical breakdown and chemical devulcanization to devulcanization Emphasis on tire rubbers - SBR (main tire rubber) is the most difficult elastomer to reclaim - Blend of elastomers can give only a best compromise

25 Closing the loop: 25 Rubber Recycling Thank you for your attention!

Benefits of Thermax N990 in EPDM Compounds

Benefits of Thermax N990 in EPDM Compounds TECHNICAL BULLETIN EPDM Compounds Thermax medium thermal carbon black N990 is manufactured by the thermal decomposition of natural gas. The thermal process provides a unique carbon black characterized