Method for reclaiming rubber, and renewed rubber compositions obtainable thereby

Patent metadata

Field	Value
Publication number	US-11041059-B2
Application number	US-201716461918-A
Country	US
Kind code	B2
Filing date	Nov 17, 2017
Priority date	Nov 18, 2016
Publication date	Jun 22, 2021
Grant date	Jun 22, 2021

Abstract

A method for reclaiming rubber comprises the steps of: (i) providing a starting material comprising a vulcanized rubber polymer; (ii) subjecting the starting material to mechanical stress and at a temperature of at least 200° C. to achieve at least a partial destruction of the cross-links and the backbone structure of the rubber polymer into fragments; and (iii) reconstituting at least part of the fragments in the presence of a branching/grafting agent to obtain a renewed rubber composition.

First claim

The invention claimed is:

1. A method for reclaiming rubber, comprising the steps of
(i) providing a starting material comprising a vulcanized rubber polymer;
(ii) subjecting the starting material to mechanical stress and at a temperature of at least 200° C. either in the absence of a fragmentation additive, or in the presence of a fragmentation additive capable of generating radicals at the temperature used, to achieve at least a partial destruction of the cross-links and the backbone structure of the rubber polymer into fragments; and
(iii) partially reconstituting the fragments obtained in step (ii) in the presence of a branching/grafting agent to obtain a renewed rubber composition.

2. Method according to claim 1 , wherein said starting material comprises a mixture of two or more distinct rubbers.

3. Method according to claim 1 , wherein said starting material comprises ground tire rubber (GTR) from car tires and/or truck tires.

4. Method according to claim 1 , wherein step (ii) is performed in the presence of a fragmentation additive capable of generating radicals at the temperature used.

5. Method according to claim 4 , wherein the fragmentation additive is a polymer which undergoes thermal degradation above 200° C.

6. Method according to claim 5 , wherein said polymer is a linear triblock copolymer based on styrene and ethylene/butylene (SEBS).

7. Method according to claim 1 , wherein step (ii) is performed in the absence of a fragmentation additive.

8. Method according to claim 1 , wherein step (ii) is performed at a temperature of at least 220° C.

9. Method according to claim 1 , wherein step (ii) is performed under mixing using in high-shear mixing equipment.

10. Method according to claim 1 , wherein said branching/grafting agent comprises a plurality of unsaturated moieties capable of reacting with free radicals.

11. Method according to claim 10 , wherein said branching/grafting agent comprises the general structure F′—R—F″, wherein each of F′ and F″ is an unsaturated moiety capable of reacting with free radicals.

12. Method according to claim 10 , wherein said branching/grafting agent is a bifunctional agent comprising C═C bonds.

13. Method according to claim 12 , wherein said bifunctional branching/grafting agent is selected from the group consisting of substituted or unsubstituted hydroquinone, substituted or unsubstituted divinylbenzene, and substituted or unsubstituted bismaleimide, which bifunctional branching/grafting agent is used under non-crosslinking conditions.

14. Method according to claim 10 , wherein said branching/grafting agent is a polymeric agent comprising multiple F moieties attached to a polymeric backbone, F being an unsaturated moiety capable of reacting with free radicals, preferably independently selected from —C═C— and C═O.

15. Method according to claim 13 , wherein said polymeric branching/grafting agent is a co-polymer of the type A-B-A, wherein each of A and B is independently selected from the group of homo- and or co-polymers of styrene (S), butadiene (B), isoprene (I) and their hydrogenated counterparts.

16. Method according to claim 1 , wherein step (iii) is performed in the presence of about 0.1-20 wt % branching/grafting agent.

17. Method according to claim 1 , wherein steps (ii) and (iii) are performed as a one-pot-process.

18. Method according to claim 17 , wherein SEBS is used.

19. Method according to claim 1 , wherein step (ii) is performed in an extruder and step (iii) is performed in a batch mixer.

20. A renewed rubber composition obtainable by a method according to claim 1 .

21. Method according to claim 1 , wherein the method is used in the manufacture of tires, roofing material, or flooring material, or wherein the method is used in roadbuilding.

22. Method according to claim 9 , wherein the high-shear mixing equipment is an extruder.

23. Method according to claim 9 , wherein the mixing is performed at a speed of at least 50 rpm for a period of 1-60 minutes.

24. Method according to claim 10 , wherein said moieties are selected from —C═C— and C═O.

25. Method according to claim 11 , wherein F′ and F″ are independently selected from —C═C— and C═O, and wherein R is an alkylic or aromatic organic moiety, or any combination thereof.

26. Method according to claim 15 , wherein said polymer is SBS (triblock, styrene-butadiene-styrene), SEBS (linear triblock copolymer based on styrene and ethylene/butylene) or SIS (styrene-isoprene-styrene).

27. Method according to claim 16 , wherein step (iii) is performed in the presence of about 1-7 wt % branching/grafting agent.

28. Method according to claim 17 , wherein steps (ii) and (iii) are performed in an extruder.

Assignees

• Univ Groningen

Inventors

• Picchioni Francesco
• Broekhuis Antonius Augustinus

Classifications

• C08C19/08

  Depolymerisation · CPC title

• B29K2009/00

  Use of rubber derived from conjugated dienes, as moulding material · CPC title

• Y02W30/62

  Plastics recycling; Rubber recycling · CPC title

• E04F15/00

  Flooring (stair treads E04F11/104; coverings not specially adapted for floors E04F13/00; borders, skirtings E04F19/02; {implements for laying flooring E04F21/20;} gratings for cleaning soles of footwear A47L23/24; {built-in gratings E04F19/10; removing floor coverings E04G23/00; carpets A47G27/00;} of similar materials to roads E01C; basic or rough floors {, structural floors} E04B5/00) · CPC title

• B29K2105/26

  Scrap {or recycled material} · CPC title