US 6,590,042 B1 · Recycled rubber processing and performance enhancement

Abstract

A process for reclaiming sulfur-cured, vulcanized rubber by combining finely ground scrap vulcanized rubber within a specialized, twin-screw extruder capable of providing strong shearing and just-on-time mixing; adding a reclaiming agent to the extruder; and masticating the rubber scrap and reclaiming agent within the extruder until the rubber scrap is devulcanized. The present invention also discloses a unique composition of reclaiming agent, which preferably includes the following compounds: accelerators TBBS, ZMBT, MBT, and TMTM; activators zinc oxide and stearic acid; and zinc salts of fatty acids and sulfur. The reclaimed rubber is suitable for use in producing high-grade, rubber products without adding a binder, or for combining with fresh rubber compounds to produce high-specification rubber products.

Claims15

Dependent claims

A chemical composition for obtaining curable elastomeric material from sulfur-cured elastomeric material having a vulcanized network, comprising:

(a) a sulphenamide group accelerator selected from the group consisting of:
(i) N-cyclohexyl-2-benzothiazole sulphenamide (CBS);
(ii) benzothiazyl-2-morpholine sulphenamide (MBS);
(iii) N-tert-butyl-2-benzothiazole sulphenamide (TBBS);
(iv) 2-(N-morpholinyldithio)-benzothiazole, and
(v) morpholinyl-thiocarbonylsulphene morpholide;
(b) at least two mercapto group accelerators selected from the group consisting of:
(i) zinc 2-mercapto benzothiazole (ZMBT);
(ii) 2-mercaptobenzothiazole (MBT), and
(iii) dibenzothiazyl-disulphide (MBTS);
(c) a thiuram group accelerator selected from the group consisting of:
(i) tetramethylthiuramic monosulphide (TMTM);
(ii) tetraethylthiuram disulphide (TETD);
(iii) tetramethylthiuram disulphide (TMTD), and
(iv) tetrabenzylthiuram disulphide (TBTD);
(d) zinc salts of fatty acids;
(e) at least one activator selected from the group consisting of:
(i) stearic acid;
(ii) methacrylic acid, and
(iii) zinc oxide, and
(f) sulfur.

18 more elements

A process for obtaining curable elastomeric material from sulfur-cured elastomeric material having a vulcanized network, such curable elastomeric material being capable of being recompounded and recurred into useful elastomeric products, such process comprising:

(A) reducing such sulfur cured elastomeric material to fine particle crumbs;
(B) providing a twin screw extruder for processing such crumb;
(C) treating such crumb, by means of such twin screw extruder, with an admixture comprising:
(a) a sulphenamide group accelerator selected from the group consisting of:
(i) N-cyclohexyl-2-benzothiazole sulphenamide (CBS);
(ii) benzothiazyl-2-morpholine sulphenamide (MBS);
(iii) N-tert-butyl-2-benzothiazole sulphenamide (TBBS);
(iv) 2-(N-morpholinyldithio)-benzothiazole, and
(v) morpholinyl-thiocarbonylsulphene morpholide;
(b) at least two mercapto group accelerators selected from the group consisting of:
(i) zinc 2-mercapto benzothiazole (ZMBT);
(ii) 2-mercaptobenzothiazole (MBT), and
(iii) dibenzothiazyl-disulphide (MBTS);
(c) a thiuram group accelerator selected from the group consisting of:
(i) tetramethylthiuramic monosulphide (TMTM);
(ii) tetraethylthiuram disulphide (TETD);
(iii) tetramethylthiuram disulphide (TMTD), and
(iv) tetrabenzylthiuram disulphide (TBTD);
(d) zinc salts of fatty acids;
(e) at least one activator selected from the group consisting of:
(i) stearic acid;
(ii) methacrylic acid, and
(iii) zinc oxide, and
(f) sulfur, and
(D) working such crumb and such admixture in such extruder for a sufficient time, at a selected temperature to break sulfur cross links within such sulfur cured elastomeric material.

22 more elements

Dependencies are inferred from the claim text.

Recycled rubber processing and performance enhancement

Life of this patent

Recycled rubber processing and performance enhancement

Life of this patent

Abstract

Claims15