Title of Invention

PROCESS FOR SURFACE ACTIVATION AND/ OR DEVULCANISATION OF SULPHUR-VULCANISED RUBBER PARTICLES

Abstract

Process for surface activation and/or devulcanisation of sulphur-vulcanised rubber particles, in which to break the sulphur bridges and to reduce the sulphur, the rubber particles are treated in a biotechnological manner in a medium with mesophilic anaerobic and/or mesophilic optionally anaerobic and/or mesophilic microaerophilic bacteria and/or one or more enzyme systems of such bacteria, and the treatment is carried out microbially and/or enzymatically by the enzyme system, preferably isolated by the bacteria.

Full Text

FORM 2 THE PATENT ACT 1970 (39 of 1970) & The Patents Rules, 2003 COMPLETE SPECIFICATION (See section 10 and rule 13) 1. PROCESS FOR SURFACE ACTIVATION AND/OR DEVULCANISATION OF SULPHUR-VULCANISED RUBBER PARTICLES 2. (A) CRISTALLO HOLDINGS INC. (B) CANADA (C) # 206,10458 Mayfield Road, Edmonton / Alberta T5P4P4, Canada. The following specification particularly describes the invention and the manner in which it is to be performed. GRANTED 17-12-2007 ORIGINAL 1176/MUMNP/2005 Description The invention relates to a process for surface activation and/or devulcanisation of sulphur-vulcanised rubber particles. Different processes are known from DE 4425049 CI, DE 1960728/ Al, US 5,506,283 for activation of comminuted scrap rubber and waste rubber. These processes are based either on physical or chemical operating principles or a combination of the two operating principles. Processes are further known from DE 4042009 C2, EP 0493732 Bl, US 5,597,851 and DE 19728036 Al for microbial and enzymatic activation of powdered rubber and rubber granulate. A process is disclosed in the documents DE 4042009 C2 and EP 0493732 Bl which is based on microbial oxidation of the polysulphide bonded sulphur in rubber vulcanisation. The oxidation of the polysulphide sulphur on the surface of the rubber particles takes place by means of chemolithotropic microorganisms in a bacterial suspension with a defined supply of oxygen. The bacteria belong to the Thiobacillus genus. The oxidation of the sulphur is generally carried out up to the sulphate stage. The end product of the process is a replasticised, low-sulphur rubber material with good suitability for vulcanisation. A similar process is disclosed in US 5,597,851. The particularity of this process consists, on the one hand, in that the thermophilic optionally ehemolithotropic Sulfolobus acidocaldarius is primarily used as a sulphur oxidising microorganism and, on the other hand, the treatment of the rubber particles is carried out merely with the enzyme system of this microorganism. The rubber particles themselves are not in direct contact with the microorganisms. A process is disclosed in DE 19728036 Al in which by biotechnological treatment of vulcanised rubber particles by means of defined reaction times/duration of oxidation, specific 2 reactive functional groups in the form of hydroxyl groups, epoxy groups and carboxyl groups are produced on the particle surface. As a result, it is possible to vulcanise the activated powdered rubber and rubber granulate with different plastics, bitumens and other polymers. Bacteria of the Thiobacillus genus are also used for the microbial oxidation. The previously known processes for microbial activation of powdered rubber and rubber granulate by sulphur oxidation comprise the following important disadvantages: 1. These activation processes are based on oxidation processes. In addition to the desired oxidation of the polysulphide sulphur, undesired oxidation of the polymer chains (attachment of free radicals) inevitably takes place simultaneously. The points on the particle surface which are still bonding-active are practically eliminated. The degree of degradation depends, amongst others, on the type of rubber (number of double bonds), the reaction temperature, the duration of the reaction and the concentration of dissolved oxygen in the suspension. 2. The degradation to the polymer chains causes, amongst others, an undesired release of specific rubber constituents (plasticisers, carbon black, 2inc oxide, etc.). 3. In order to avoid foreign contamination, the processes have to be carried out at very low pH values (1 to 3) which necessitates additional requirements for the materials of the bioreactors and for the waste water treatment. These disadvantages can be avoided by anaerobic processes. Such a process is known from Bredberg (K Bredberg, J. Perssom, M. Christiansson, B. Stenberg, O. Hoist: 'Anaerobic desulfurization of ground rubber with the thermophilic archaeon Pyrococcus furiosus - a new method for rubber recycling' in the journal Appl. Microbiol. Biotechnol. (2001) 55, pages 43-48), by using the sulphur-reducing, anaerobic, hyperthermophilic archaeon, Pyrococcus furiosus. This process nevertheless has the following disadvantages - in particular due to the hyperthermophilic characteristic of the archaeon: 3 The treatment of the powdered rubber over a lengthy period at a temperature range of 90 - 100 °C leads to degradation of the polymer chains of the elastomers and thus to deterioration of the significant material technical parameters (tensile strength, elongation at break, abrasion, etc.). 2. Due to the high temperature exposure of the powdered rubber, increased rubber constituents are released (plasticisers, carbon black, zinc oxide, chemical protective agents, etc.) which have a toxic effect on the microorganisms and thus restrict the process of desulphurisation or lead to a breakdown of the process. 3. Carrying out the process at such a high temperature range is uneconomical with regard to large-scale production and of ecological concern (release of toxic materials into the process waste water). The object of the invention, therefore, is to provide a method for surface activation and/or devulcanisation of sulphur-vulcanised rubber particles which is" carried out substantially at temperatures below 90 °C and avoids the aforementioned disadvantages of microbial oxidation processes. This object is achieved according to the invention by a process with the features of claim 1. Advantageous developments and embodiments are provided in the claims dependent on claim 1. The invention is based on the consideration that a process for surface activation and/or devulcanisation of sulphur-vulcanised rubber particles is provided, in which in order to break the sulphur bridges and to reduce the sulphur, the rubber particles are treated in a biotechnological manner in a medium with mesophilic anaerobic and/or mesophilic optionally anaerobic and/or mesophilic microaerophilic bacteria and/or one or more enzyme systems of such bacteria. Bacteria which can exist both with and without oxygen are understood by the term optionally anaerobic bacteria. 4 The essential difference from the process disclosed in Bredberg lies in the use of mesophilic microorganisms. The optimal living conditions of mesophilic bacteria are at 20 to 45 °C. Thus the process according to the invention functions at temperatures markedly below 90 °C. As a result, the aforementioned disadvantages of treatment with hyperthermophilic microorganisms are removed or at least greatly reduced. As the bacteria used in the process according to the invention are moreover anaerobic and/or optionally anaerobic and/or microaerophilic bacteria, the process functions by excluding oxygen or with very low concentrations of oxygen. As a result, the aforementioned disadvantages of the microbial oxidation process are avoided. The operating principle of this treatment of the rubber particles according to the process of the invention, consists in the microorganisms breaking the sulphur bridges of the vulcanised rubber on the particle surface and partially or completely reducing the sulphur, without thereby degrading the polymer chains of the elastomers. By means of the process according to the invention, activated rubber particles are produced which, in comparison with non-activated rubber particles, provide a high vulcanisation capability. As a result, it is possible by using such activated rubber particles, in particular in the form of powdered rubber and rubber granulate to produce high quality products. The treatment of the rubber particles during the process according to the invention can be microbial. and/or enzymatic. In the case of an enzymatic process the treatment is, in particular, carried out exclusively by the enzyme system of the bacteria, preferably isolated from the bacteria. By the term microbial treatment is understood that the bacteria themselves come into contact (interaction) with the surface of the rubber particles. During enzymatic treatment, however, the treatment, i.e. breaking the sulphur bridges and/or reducing the sulphur, is carried out only by the enzyme system or enzyme systems of the bacteria. In detail, an enzymatic treatment can be carried out in the following manner: firstly the bacteria are grown in a preculture without contact with the sulphur-vulcanised rubber particles to be treated, by using a further sulphur substtate, for example elemental sulphur. 5 Subsequendy, the bacteria are broken down and the enzyme system is isolated (harvested) by generally known processes. The treatment of the sulphur-vulcanised rubber particles is then carried out exclusively by the isolated enzyme system. It is, however, also possible that the bacteria produce the enzyme system in situ, i.e. the enzyme system required for the enzymatic treatment is not previously isolated. Usefully, the medium for treating the rubber particles contains water, nutrients, a carbon source and bacteria or consists thereof and is therefore a suspension. An advantageous development provides that the concentration of the rubber particle material in the medium is substantially maintained below 35 per cent by mass. Higher rubber particle concentrations cause problems when intermixing die reaction mass, during mass transfer and during bacterial growth, for example due to higher concentrations of toxic chemical substances, in particular antioxidants. It can further be provided that the medium for reducing temperature and/or concentration gradients is intermixed. Preferably the intermixing is carried out carefully, for example by means of an agitator. A further useful variant of the process according to the invention provides that the treatment is carried out under anaerobic or microaerophilie conditions. Moreover it can be provided that the treatment is carried out substantially at temperatures below 90 °C, in particular below 50°C, preferably within an optimal temperature range for mesophilic bacteria, which is approximately at 20 to 45 °C. The treatment is preferably carried out at temperatures' in a range of 33 to 37 °C. As a result, the treatment of rubber particles is carried out as a whole under conditions which are optimally suited to the living conditions of the mesophilic anaerobic and/or mesophilic optionally anaerobic and/or mesophilic microaerophilic bacteria. Moreover, the aforementioned disadvantages of the known processes are substantially prevented thereby. 6 According to a development of the process, the pH value lies in the range of 5 to 9, in particular from 6 to 8. Moreover, the residence dwell time of the rubber particles can be in the region of 4 to 8 days, in particular from 5 to 7 days, preferably approximately 6 days. Optimally successful desulphurisation is in particular achieved by observing the following process parameters and conditions: 33 to 37°C 6 to 8 Careful intermixing by means of an agitator 6 days 0.2 to 0.4 mm Process temperature: pH value: Intermixing regime: Mean residence time: Particle size of rubber particles: A useful development of the process according to the invention provides that the bacteria used in the medium and/or for producing the enzyme system, arc bacteria capable of sulphur respiration, i.e. sulphur reduction. In tests it has been established that according to a corresponding adaptation phase, different anaerobic or optionally anaerobic or microaerophilic mesophilic bacteria are able to break the sulphur bridges in the vulcanised rubber and to reduce the sulphur. Positive results were achieved with, amongst others, the bacteria Desulfuromonas thiophila, Desulfuromonas palmitatis, Sulfurospirillum deleyianum and Desulfuromonas acetoxidans. Advantageously, bacteria are therefore used which substantially belong to one or more of these bacterial strains. Moreover, all or some of the bacteria are mixed populations. Very good desulphurisation rates are produced by the use of an anaerobic mesophilic mixed population which, in addition to the sulphur reducing bacteria, provides significant proportions of methanogenic bacteria. This population was isolated from Saale river sediment and is characterised by particular stability. 7 An embodiment of the invention provides that, with the rubber particles to be treated, it substantially refers to rubber powder and/or powdered rubber and/or rubber granulate. By rubber powder and powdered rubber is understood a material with a particle diameter of less than I. mm, by rubber granulate a material with a particle diameter of between ca. 1 mm and 5 mm. It is useful and advantageous when the particle size of the rubber particles to be treated is in the region of 0.1 to 0.6 mm, in particular from 0.2 to 0.4 mm, i.e. when it refers to rubber powder and powdered rubber. Usefully, according to a development it is provided that the rubber particles to be treated are substantially rubber particles made up of sulphur-vulcanised rubber types or composites based on sulphur-vulcanised rubber types. The process according to the invention is essentially suited to surface activation and/or devulcanisation of all sulphur-vulcanised rubber types, for example SBR (Styrol Butadiene Elastomer), NR {Natural Rubber), NBR (Acrylonitrile Butadiene Elastomer, Nitrile Rubber) and EPDM (Ethylene Propylene Diene Elastomer). According to an advantageous development the rubber particles are produced from scrap rubber (for example old tyres, technical rubber products such as seals, sections, rubber mouldings, conveyor belts) and/or waste rubber (production waste of the rubber producing and rubber processing industry). In this manner the process according to the invention serves to reclaim scrap and/or waste rubber. A further embodiment provides that the rubber particles to be treated are produced in a comminution process, in particular a peeling process and/or hot grinding and/or cold grinding and/or cryogenic grinding and/or wet grinding. It is particularly advantageous when, during the comminution process to produce the rubber particles, the temperature of the rubber particles remains so low, in particular substantially lower than 90 °C, that thermooxidative degradation of the rubber particles is substantially avoided. A particularly advantageous development of the process according to the invention provides that the surface activation and/or devulcanisation is substantially restricted to the rubber particle surface and/or layers close to the surface, in order not to alter the material properties 8 of the main mass of the rubber particle material. The layer close to the surface should therefore be at most 300 zun thick. This means that the effect of mesophilic desulphurisation is deliberately restricted to the particle surface and/or layers close to the surface. Usefully, the treatment of the rubber particles is carried out in a bioreactor. A bioreactor is an apparatus for carrying out materials conversion with microorganisms in a reproducible and controlled manner. Moreover, it can further be provided that the addition of the rubber particles to be treated into the bioreactor and/or the removal of the rubber particles to be treated from the bioreactor is carried out continuously or quasi-continuously or discontinuously. Alternatively or additionally, it can be further provided that the bioreactor is operated such that when removing the treated rubber particles from the bioreactor, no or only small amounts of bacteria and/or medium containing enzymes for treating the rubber particles are discharged therewith and/or come into contact with atmospheric oxygen. This can be achieved by sedimentation and subsequent removal of the rubber particles under anaerobic conditions. Usefully, in the method the sulphur bridges contained in the rubber particles are at least partially broken by the treatment and the sulphur is transferred into one or more gas-forming reaction products. One of the gas-forming reaction products can be hydrogen sulphide. A particularly advantageous development provides that the hydrogen sulphide formed during the treatment of the rubber particles is continuously or quasi-continuously removed from the gas phase. As a result, inhibition and/or toxitication of the bacteria can be prevented. An advantageous development of the process according to the invention provides that the treated rubber particles are washed with water after treatment, in particular to reduce salt loading, and subsequendy are carefully dried, in particular substantially at temperatures below 90 °C. A further embodiment provides that rubber particles surface activated by means of the treatment, in particular powdered rubber, are produced which are used to manufacture rubber products. In this connection, these new rubber products can be substantially manufactured 9 either only from treated surface activated rubber particles or from surface activated rubber particles with admixed virgin rubber, in particular by means of chemical vulcanisation. It can further be provided that rubber particles surface activated by means of the treatment, in particular powdered rubber, are produced which are used to manufacture elastomer alloys, in particular by phase coupling with plastics, preferably Polypropylene (PP) and/or Polyurethane (PU). In addition to improving the material properties of the rubber products manufactured in this manner, the use of such surface activated rubber particles also results in a reduction of the specific product costs. For example, the admixing of scrap powdered rubber activated according to the process according to the invention with virgin rubber, in comparison with admixing untreated powdered rubber, leads to a significant improvement of the material technical parameters of the resulting product, in particular the stress-strain behaviour, the tear growth resistance and the impact resilience. It can further be established that by compounding thus activated scrap powdered rubber and EPDM powdered rubber with thermoplastics, in particular with Polypropylene - materials are produced of which the mechanical physical properties approach those of thermoplastic elastomers. In particular, an improvement can be seen in the elasticity compared to the use of comparable untreated scrap powdered rubber. This indicates that it results in intensive interdiffusion of the chains of the polymer phase and the elastomer phase and possibly also chemical vulcanisation of the two phases (intensive phase coupling). The invention is further described hereinafter with reference to an embodiment. Cryogenically milled EPDM powdered rubber, with a particle size of less than 0.4 mm, is subjected to microbial surface vulcanisation under anaerobic conditions. With an activation period of 8 days a level of desulfurisation of the rubber is achieved of circa 4 %. The microbial activated powdered rubber and non-activated powdered rubber of the same gross sample are respectively mixed and vulcanised with EPDM-virgin rubber at the ratio 1:1. 10 The tensile strength and the elongation at break of the respective end products and - by comparison - of EPDM virgin rubber are shown in the following table: End product vulcanised from: Tensile Strength in MPa Elongation at Break in % EPDM - Virgin rubber (without admixing powdered rubber) 28 595 50 % EPDM - Virgin rubber +50 % activated powdered rubber 25 555 50 % EPDM - Virgin rubber +50 % non-activated powdered rubber 17,5 385 The comparison of the given values for the significant material parameters of tensile strength and elongation at break clearly shows that treatment according to the invention of rubber particles, i.e. in the example considered, microbial activation carried out under anaerobic conditions of powdered rubber, leads to a considerable improvement of the material properties compared to non-treated rubber particles. As a whole, therefore, the activated rubber particles treated according to the process according to the invention, show improved vulcanisation properties, in comparison with non-treated rubber particles and permit the production of better quality articles. 11 We claim: 1. Process for surface activation and/or devulcanisation of sulphur-vulcanised rubber particles, in which to break the sulphur bridges and to reduce the sulphur, the rubber particles are treated in a biotechnological manner in a medium with mesophilic anaerobic and/or mesophilic optionally anaerobic and/or mesophilic microaerophilic bacteria and/or one or more enzyme systems of such bacteria, and the treatment is carried out microbially and/or enzymatically by the enzyme system, preferably isolated by the bacteria. 2. Process as claimed in claim 1, in which the medium for treating the rubber particles contains or consists of water and nutrients and a carbon source and bacteria, and/or the concentration of the rubber particle material in the medium is maintained below 35% by mass. 3. Process as claimed in any one of the preceding claims, in which to reduce the temperature and/or concentration gradients the medium is intermixed, in particular carefully intermixed, preferably by means of an agitator. 4. Process as claimed in any one of the preceding claims, in which the treatment is carried out under anaerobic or microaerophilic conditions. 5. Process as claimed in any one of the preceding claims, in which the treatment is carried out at temperatures below 90 °C, in particular below 50 °C, preferably within an optimal temperature range,for mesophilic bacteria, in particular 33 to 37°C. 6. Process as claimed in any one of the preceding claims, in which the treatment is carried out at a pH value in the region of 5 to 9, in particular from 6 to 8. 7. Process as claimed in any one of the preceding claims, in which the residence time of the rubber particles in the medium is in the region of 4 to 8 days, in particular 5 to 7 days, preferably 6 days. 12 8. Process as claimed in any one of the preceding claims, in which the bacteria are or comprise bacteria capable of sulphur respiration, i.e. sulphur reduction, and in particular belong to one or more of the following bacterial strains: Desulfuromonas thiophila, Desulfuromonas palmitatis, Sulfurospirillum deleyianum, Desulfuromonas acetoxidans. 9. Process as claimed in any one of the preceding claims, in which the bacteria are or comprise mixed populations. 10. Process as claimed in any one of the preceding claims, in which the rubber particles to be treated are or comprise rubber powder and/or powdered rubber and/or rubber granulate, the particle size preferably being in the region of 0.1 to 0.6 mm, in particular 0.2 to 0.4 mm. 11. Process as claimed in any one of the preceding claims, in which the rubber particles to be treated are or comprise rubber particles made up of sulphur-vulcanised rubber types or composites based on sulphur-vulcanised rubber types. 12. Process as claimed in any one of the preceding claims, in which the rubber particles to be treated are on comprise rubber particles made of scrap rubber and/or waste rubber and the process thus serves to reclaim scrap and/or waste rubber. 13. Process as claimed in any one of the preceding claims, in which the rubber particles to be treated are produced in a comminution process, in particular a peeling process and/or hot grinding and/or cold grinding and/or cryogenic grinding and/or wet grinding, preferably the temperature of the rubber particles remaining so low, in particular lower than 90 °C, that thermooxidative degradation of the rubber particles is substantially avoided. 14. Process as claimed in any one of the preceding claims, in which the surface activation and/or devulcanisation is substantially restricted to the rubber particle surface and/or layers close to the surface, in particular with a thickness of at most 300 nm, in order not to alter the material properties of 13 the main mass of the rubber particle material. 15. Process as claimed in any one of the preceding claims, in which the treatment of the rubber particles is carried out in a bioreactor. 16. Process as claimed in claim 15, in which the addition of the rubber particles to be treated into the bioreactor and/or the removal of the rubber particles to be treated from the bioreactor is carried out continuously or quasi-continuously or discontinuously and/or the bioreactor is operated such that when removing the treated rubber particles from the reactor no or only small amounts of bacteria and/or medium containing enzymes for treating the rubber particles are discharged therewith and/or come into contact with atmospheric oxygen, in particular by means of sedimentation of the rubber particle material and its subsequent removal under anaerobic conditions. 17. Process as claimed in any one of the preceding claims, in which the sulphur bridges contained in the rubber particles are at least partially broken by the treatment and the sulphur is transferred into one or more gas-forming reaction products, hydrogen sulphide being in particular one of the gas-forming reaction products, which preferably is continuously or quasi-continuously removed from the gas phase to avoid inhibition and/or toxification of the bacteria. 18. Process as claimed in any one of the preceding claims, in which the treated rubber particles are washed with water after treatment, in particular to reduce salt loading, and subsequently are carefully dried, in particular at temperatures below 90 °C. 19. Process as claimed in any one of the preceding claims, in which rubber particles surface activated by means of the treatment, in particular powdered rubber, are produced which are used to manufacture rubber products, which in particular are produced only from the treated surface activated rubber particles, of from the surface activated rubber particles and admixed virgin rubber. 14 20. Process as claimed in any one of the preceding claims, in which rubber particles surface activated by means of the treatment, in particular powdered rubber, are produced which are used to produce elastomer alloys in particular by phase coupling with plastics, preferably Polypropylene (PP) and/or Polyurethane (PU). Dated this 16th day of October 2005. Dr. Rajeshkumar H. Acharya Advocate & Patent Agent For and on Behalf of Applicant 15

Documents:

1176-mumnp-2005-cancelled pages(17-12-2007).pdf

1176-mumnp-2005-claims(granted)-(17-12-2007).doc

1176-mumnp-2005-claims(granted)-(17-12-2007).pdf

1176-mumnp-2005-claims.doc

1176-mumnp-2005-claims.pdf

1176-MUMNP-2005-CORRESPONDENCE 26-6-2008.pdf

1176-mumnp-2005-correspondence(17-12-2007).pdf

1176-mumnp-2005-correspondence(ipo)-(30-1-2008).pdf

1176-mumnp-2005-correspondence-others.pdf

1176-mumnp-2005-correspondence-received.pdf

1176-mumnp-2005-correspondence-send.pdf

1176-mumnp-2005-description (complete).pdf

1176-mumnp-2005-form 1(24-10-2005).pdf

1176-mumnp-2005-form 18(21-2-2006).pdf

1176-mumnp-2005-form 2(granted)-(17-12-2007).doc

1176-mumnp-2005-form 2(granted)-(17-12-2007).pdf

1176-mumnp-2005-form 26(18-8-2005).pdf

1176-mumnp-2005-form 3(18-8-2005).pdf

1176-mumnp-2005-form-1.pdf

1176-mumnp-2005-form-18.pdf

1176-mumnp-2005-form-2.doc

1176-mumnp-2005-form-2.pdf

1176-mumnp-2005-form-26.pdf

1176-mumnp-2005-form-3.pdf

1176-mumnp-2005-form-5.pdf

1176-mumnp-2005-form-pct-isa-210(24-10-2005).pdf

1176-mumnp-2005-granted.pdf

1176-mumnp-2005-pct-search report.pdf