Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J11/00—Recovery or working-up of waste materials
  • C08J11/04—Recovery or working-up of waste materials of polymers
  • C08J11/10—Recovery or working-up of waste materials of polymers by chemically breaking down the molecular chains of polymers or breaking of crosslinks, e.g. devulcanisation
  • C08J11/18—Recovery or working-up of waste materials of polymers by chemically breaking down the molecular chains of polymers or breaking of crosslinks, e.g. devulcanisation by treatment with organic material
  • C08J11/28—Recovery or working-up of waste materials of polymers by chemically breaking down the molecular chains of polymers or breaking of crosslinks, e.g. devulcanisation by treatment with organic material by treatment with organic compounds containing nitrogen, sulfur or phosphorus
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08C—TREATMENT OR CHEMICAL MODIFICATION OF RUBBERS
  • C08C19/00—Chemical modification of rubber
  • C08C19/08—Depolymerisation
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2319/00—Characterised by the use of rubbers not provided for in groups C08J2307/00 - C08J2317/00
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2321/00—Characterised by the use of unspecified rubbers
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
  • Y02W30/00—Technologies for solid waste management
  • Y02W30/50—Reuse, recycling or recovery technologies
  • Y02W30/62—Plastics recycling; Rubber recycling
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T152/00—Resilient tires and wheels
  • Y10T152/10—Tires, resilient

Definitions

• This invention relates to the field of waste recycling, and in particular to a method of devlucanizing a cross-linked elastomer material, such as scrap from molding operations.
• Devulcanization is a method of recycling waste thermoset elastomeric material to produce a material that can be revulcanized into useful products.
• a thermoset elastomer results from a polymer that is irreversibly cured.
• Prior art processes for devulcanization use chemical, ultrasonic, biological with microorganisms, mechanical, microwave or steam techniques.
• HSM high shear mixing
• US patent no. 7,461,970 assigned to the applicant, describes such a process. It uses a mixing apparatus having two opposing mixing members rotatable relative to one another about an axis and that have facing surfaces which extend away from the axis to define a mixing chamber. An array of mixing formations on at least one of the surfaces acts to mix material and propel the material within the chamber toward the axis.
• This mechanical process has demonstrated the ability to un-crosslink thermoset elastomers using shear energy such that approximately 60% of the original physical properties of the materials are recovered.
• WO 03/014206A1 assigned to the applicant describes a process for treatment of cross-linked elastomers such that a predetermined portion of the untreated material remains as vulcanized granules to thereby produce a flowable material comprising vulcanised elastomer dispersed in a matrix of devulcanized elastomer.
• the inventors have found that the addition of a suitable catalyst with a thiol terminus to the mechanical process of high shear mixing has been shown to significantly improve the properties of materials recovered and approximately halve the processing time.
• thermoset cross-linked elastomer material comprising subjecting the material to a mechanical mixing process at a temperature of less than 80°C in the presence of an amount of 0.5 to 2% by wt. of a biological catalyst having a thiol terminus.
• biological catalyst is meant a catalyst obtained from a biological source, such as hair.
• Amino acids with thiol groups represent a suitable biological source.
• a preferred catalyst is L-cysteine.
• the addition of such a catalyst can improve the properties by as much as 12.5% and reduce the processing time by 50%.
• the amount of 0.5 to 2 % by weight was selected as a range because this is the typical dosage of sulphur in a rubber compound, and the amount of biological catalyst was selected to match this dosage.
• Biological catalysts are non-toxic, readily available and cost effective at the percentage and do not cause re-cure of the rubber without planned addition of rubber accelerators. They are effective at modest temperatures, ⁇ 80°C, and preferably in the range 25 - 40°C. If the temperature of the devulcanization process exceeds about 80°C, the material may re- vulcanize, thus defeating the object of the devulcanization process.
• FIG. 1 shows a high shear mixer (HSM) 100, of the type described in US patent no.
• HSM high shear mixer
• a first process was conducted using a control compound, 65A Natural Rubber, and using an accepted HSM protocol and then post processed sufficiently to produce a compoundable masterbatch.
• Sulphur and rubber accelerator were added to achieve a curable control compound.
• the physical and rheological properties of the control compound were then assessed using a moving die rheometer.
• a second process was conducted using the same control compound under the identical HSM and compounding protocol as used in the said first process. However, 1% by weight of L- Cysteine material was pre-dispersed in the said control compound during the HSM process immediately before the final plasticization step. The process was controlled within the temperature range of 25°C-80°C, the preferred temperature being 60°C.
• a curable compoundable masterbatch was produced as a result.
• the same physical and rheological properties of said novel compoundable masterbatch were assessed to determine the effect of the addition of the catalyst - L-Cysteine.
• L-Cysteine is a naturally occurring amino acid and nutritional supplement. It is also used as an expectorant in medicine to liquefy mucous by breaking disulphide bonds in proteins. Since L-Cysteine is ingested by humans for medical purposes it is clearly non-toxic.
• Chains, 200, of carbon atoms C are cross-linked to each other by chemical bonds, or crosslinks 202, with sulphur elements S.
• the mechanically applied shear energy severs more of the sulphur links 202 than carbon links thereby preserving more of the carbon chains 200. This in turn preserves more of the material's original properties and also allows the process to be completed in less time.
• the process is useful for devulcanizing cross-linked thermoset elastomer material, such as scrap rubber from molding operations.
• This rubber has a high value.
• the devulcanizing process restores the rubber to a pre-vulcanized state, wherein it may be revulcanized into useful products.
• Scrap rubber wastage from molding operations can be re-used.
• the invention is also applicable to scrap rubber from tires, although this is subject to a number of other treatments and is generally not as suitable for full recycling.

Landscapes

• Chemical & Material Sciences (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Sustainable Development (AREA)
• Separation, Recovery Or Treatment Of Waste Materials Containing Plastics (AREA)
• Processing And Handling Of Plastics And Other Materials For Molding In General (AREA)
• Processes Of Treating Macromolecular Substances (AREA)
• Processing Of Solid Wastes (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Compositions Of Macromolecular Compounds (AREA)

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• 2011
  • 2011-11-25 US US13/304,509 patent/US8673989B2/en active Active
• 2012
  • 2012-11-19 DK DK12852015.2T patent/DK2782958T3/en active
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  • 2012-11-19 WO PCT/CA2012/001063 patent/WO2013075216A1/en not_active Ceased
  • 2012-11-19 CA CA2856319A patent/CA2856319C/en active Active
  • 2012-11-19 MX MX2014006236A patent/MX347891B/es active IP Right Grant
  • 2012-11-19 AU AU2012343295A patent/AU2012343295A1/en not_active Abandoned
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  • 2012-11-19 EP EP12852015.2A patent/EP2782958B1/en active Active
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  • 2012-11-19 JP JP2014542649A patent/JP6232381B2/ja active Active
  • 2012-11-19 KR KR1020147017356A patent/KR102049127B1/ko active Active
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• 2014
  • 2014-05-21 IN IN960MUN2014 patent/IN2014MN00960A/en unknown

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