CA2134186A1 - Recycling of natural and synthetic rubber - Google Patents
Recycling of natural and synthetic rubberInfo
- Publication number
- CA2134186A1 CA2134186A1 CA 2134186 CA2134186A CA2134186A1 CA 2134186 A1 CA2134186 A1 CA 2134186A1 CA 2134186 CA2134186 CA 2134186 CA 2134186 A CA2134186 A CA 2134186A CA 2134186 A1 CA2134186 A1 CA 2134186A1
- Authority
- CA
- Canada
- Prior art keywords
- sulphur
- paste
- process according
- crumbs
- elastomeric materials
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
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
- 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
Landscapes
- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Sustainable Development (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Compositions Of Macromolecular Compounds (AREA)
- Separation, Recovery Or Treatment Of Waste Materials Containing Plastics (AREA)
- Processes Of Treating Macromolecular Substances (AREA)
Abstract
A process of recycling used sulphur-cured elastomeric materials comprising masticating the said elastomeric materials at temperatures below 40°C with a chemical paste which is capable of initiating proton exchange in a controlled manner and thereby open up or delink the vulcanised network of the elastomeric materials. The chemical paste is made from the zinc salt of dimethydithiocarbamate and mercaptobenzothiazole in the molar ratio in the range of 1:1 to 1:12 dispersed in diols and in the presence of stearic acid, zinc oxide and sulphur.
This mixture, which may be termed the 'paste', when blended with tyre crumbs or any other vulcanised crumbs in concentrations of 6 parts binder per 100 parts of rubber crumbs on a mill effectively delinks the vulcanised network and renders the compound ready for moulding and vulcanization. The total milling period, which occurs at temperatures below 40°C, takes only 7 to 10 minutes. Alternatively, the binder and tyre crumbs could be first mixed in an intermix and subsequently milled in an open mill.
The obtained recycled rubber compounds display satisfactory level of physical and dynamic characteristics. Such compounds can be directly used in moulded goods or in admixture with fresh compounds in tyres and related areas.
This mixture, which may be termed the 'paste', when blended with tyre crumbs or any other vulcanised crumbs in concentrations of 6 parts binder per 100 parts of rubber crumbs on a mill effectively delinks the vulcanised network and renders the compound ready for moulding and vulcanization. The total milling period, which occurs at temperatures below 40°C, takes only 7 to 10 minutes. Alternatively, the binder and tyre crumbs could be first mixed in an intermix and subsequently milled in an open mill.
The obtained recycled rubber compounds display satisfactory level of physical and dynamic characteristics. Such compounds can be directly used in moulded goods or in admixture with fresh compounds in tyres and related areas.
Description
Improvements in and rel~tin~ to the recycling of natural and synthetic rubber s Field of Invention This invention concellls the recycling of used elastomeric products such as tyres, mouldings, gloves and beltings made from natural rubber or synthetic rubber or combinations thereof which were originally vulcanised by the conventional sulphur accelerated vulcanising systems.
Prior Art Recycling of rubber from used rubber products is well-known in the industry where some 200,000 tonnes of recycled rubber is involved. The conventional rubber recycling processes use high temperature and catalysts to digest the elastomeric material being recycled resulting 15 in a high col~u~p~ion of energy and appreciable degradation of the base polymer. Thus, the recycled rubber has uses which are restricted by its poor physical prope,lies. A typical recycled rubber has tensile strength not more than 5 to 6 MPa while raw natural rubber with the same compound can provide over 20MPa. The conventional process is also labour intensive and has difficult and complicated quality management and standardisation.
The conventional rubber recycling process in essence consists of taking vulcanised rubber crumbs, ~lmixing them with catalysts and subjecting the admixture to tempel~Lu~es of more than 170C for periods of more than 4 to 6 hours in a digestor. The resulting material is then subjected to mastication until it is rendered into sheet form. Such recycled rubber 25 products are used in small proportions as processing aids or diluents with fresh rubber compounds. The quantity of recycled rubber in the mixture will adversely affect the physical and dynamic propellies of the final vulc~ni~te.
Used tyres and other rubber articles are becoming an environmental hazard globally. There 30 iS a distinct demand for a satisfactory recycling process to address this ever increasing environmental problem. The used tyre mountains now in existence globally are a fire hazard. Many attempts and approaches have been made to assuage this environmental issue.
Among these could be mentioned the use of pelletized tyre crumbs for road surfacing, the ` ~13~186 burning of such crumbs to generate energy and so on.
;
It is known that hexamethylene tetramine and resorcinol, in the presence of accelerators, do tend to cut crosslinks in vulcanised rubber and this is reported in lil~Lalule em~n~ting from 5 Czechoslovakia (hereinafter "the Czechoslovakian process"). But this process is uncontrollable and produces variation and degradation in the resultant recycled rubber.
While the mechanism of this reaction is not described in detail, it is believed that some form of proton transfer reaction is involved.
10 Thus, none of the conventional methods or approaches have succeeded in making any real progress in solving this vexing global problem.
Objects of the invention There is required a method of effectively recycling used rubber products entailing a cost S effective process which will open up the vulcanized network structure in used rubber crumbs without unduly degrading the backbone polymer. The closer such recycled rubber preserves the native physical and dynamic characteristics of original natural and synthetic rubbers, the wider the applicability of such rubbers in further rubber manufacturing process.
20 D~s_,;"lion of the invention We have now developed a process which essentially converts used rubber product crumbs into a material having properties which approach that of fresh elastomers in similar compounds. This process is elegant, simple and is neither energy nor labour intensive.
25 We have reinvestigated the Czechoslovakian process and have now developed an entirely new system to effect the proton transfer reaction. Our process, however, does not use any hexamine which is a hazardous chemical to handle. In~te~d, we have relied on chemicals already used in the conventional rubber manufacturing process.
30 Our discovery essentially coll-plises of the use of a chemical paste which is capable of initiating proton exchange in a controlled manner at lell~pel~lures below 40C and thereby open up or delink the vulcanised network of elastomeric material, preferably the chemical paste co-llplises zinc salt of dimethydithiocarbamate (hereinafter "ZDC") and mercaplobenzothiazole (hereinafter "MBT"), in the molar ratio in the range of 1:1 to 1:12 dispersed in a diol, preferably diethylene glycol, and in the presence of stearic acid, zinc oxide and sulphur. This mixture, which may be termed the 'paste', when blended with tyre crumbs or any other vulcanised crumbs in concenlr~lions of prerel~bly 6 parts paste per 100 5 parts of rubber crumbs on a mill effectively delinks the vulcanised network and renders the compound ready for moulding and vulc~ni7~tion. The total milling period, which occurs at tempel~lures below 40C, takes only 7 to 10 minlltes. Alternatively, the binder and tyre crumbs could be first mixed in an intermix and subsequently milled in an open mill.
o We have also developed a more convenient method of h~n~ling the chemicals of the paste, i.e. by the master batch method. The paste chemicals are first mixed with fresh or vulcanised rubber in the proportion of paste:rubber ratios of between 90:10 to 40:60. This master batch mixture can be mixed with vulcanised crumbs in proportions which will ensure that the ultimate ratio of binder:rubber is 6:100. Parts are parts by weight.
Some embodiments of the invention will now be described, by way of illustration, with reference to the following Examples and Tables, and the propel lies of the ensuing compounds illustrate the manner in which this invention is effective in practice.
Example 1 The following materials are mixed in the given proportions:-1. 2-mercaptobenzothiazol (MBT) 20.0 2. Zinc dimethyldithiocarbamate (ZDC)6.0 3. Stearic acid 2.0 4. Zinc oxide 2.0 5. Sulphur 1.5 6. Diethylene glycol 12.0 The powders are first i~ ely mixed with vigorous stirring and then the diethylene glycol added to render the whole mixture into a smooth paste.
500 g of tyre crumbs are milled in a 2 roll mill for 3 minu~e and then 15 g of the binder added. After further milling for 2 minutes another 15 g of the binder is introduced. The final 2 minutes of milling are carried out at narrow nip. By this time, it is possible to sheet ~134186 out the compound which is ready for vulc~ni7~tion at 150C for 15 to 30 minutes.Properties of the vulc~ni.~tes using tyre crumbs originating from Malaysia and Europe are shown in Table 1 below.
Table 1 CHARACTERISTICS OF VULCANISATES
prepared from tyre crumbs of 100% natural rubber Country of origin Malaysia Europe Chdl dcL~ Lics 1 2 3 4 1. Size (mm) 0.1 - 0.5 0.1 - 0.1 - 0.5 > 1.0 0.5 2. Binder content 6 6 6 6 (parts per hundred of crumb) 3. Vl,lranicn~ion (C) 143 155 143 143 4. Mooney viscosity, M,100 68 68 75 120 5. Stress at 100% elongation (MPa) 3 3 3.5 5.5 6. Tensile strength (MPa) 12.1 12.7 14.5 16 7. Elongation at break (%) 350 350 375 400 8. Elongation set (%) 15 15 15 12 9. Relative concenLIdLion of chains, 1.1 1.2 1.2 1.3 Vrelx104 (mole/cm3)*
Prior Art Recycling of rubber from used rubber products is well-known in the industry where some 200,000 tonnes of recycled rubber is involved. The conventional rubber recycling processes use high temperature and catalysts to digest the elastomeric material being recycled resulting 15 in a high col~u~p~ion of energy and appreciable degradation of the base polymer. Thus, the recycled rubber has uses which are restricted by its poor physical prope,lies. A typical recycled rubber has tensile strength not more than 5 to 6 MPa while raw natural rubber with the same compound can provide over 20MPa. The conventional process is also labour intensive and has difficult and complicated quality management and standardisation.
The conventional rubber recycling process in essence consists of taking vulcanised rubber crumbs, ~lmixing them with catalysts and subjecting the admixture to tempel~Lu~es of more than 170C for periods of more than 4 to 6 hours in a digestor. The resulting material is then subjected to mastication until it is rendered into sheet form. Such recycled rubber 25 products are used in small proportions as processing aids or diluents with fresh rubber compounds. The quantity of recycled rubber in the mixture will adversely affect the physical and dynamic propellies of the final vulc~ni~te.
Used tyres and other rubber articles are becoming an environmental hazard globally. There 30 iS a distinct demand for a satisfactory recycling process to address this ever increasing environmental problem. The used tyre mountains now in existence globally are a fire hazard. Many attempts and approaches have been made to assuage this environmental issue.
Among these could be mentioned the use of pelletized tyre crumbs for road surfacing, the ` ~13~186 burning of such crumbs to generate energy and so on.
;
It is known that hexamethylene tetramine and resorcinol, in the presence of accelerators, do tend to cut crosslinks in vulcanised rubber and this is reported in lil~Lalule em~n~ting from 5 Czechoslovakia (hereinafter "the Czechoslovakian process"). But this process is uncontrollable and produces variation and degradation in the resultant recycled rubber.
While the mechanism of this reaction is not described in detail, it is believed that some form of proton transfer reaction is involved.
10 Thus, none of the conventional methods or approaches have succeeded in making any real progress in solving this vexing global problem.
Objects of the invention There is required a method of effectively recycling used rubber products entailing a cost S effective process which will open up the vulcanized network structure in used rubber crumbs without unduly degrading the backbone polymer. The closer such recycled rubber preserves the native physical and dynamic characteristics of original natural and synthetic rubbers, the wider the applicability of such rubbers in further rubber manufacturing process.
20 D~s_,;"lion of the invention We have now developed a process which essentially converts used rubber product crumbs into a material having properties which approach that of fresh elastomers in similar compounds. This process is elegant, simple and is neither energy nor labour intensive.
25 We have reinvestigated the Czechoslovakian process and have now developed an entirely new system to effect the proton transfer reaction. Our process, however, does not use any hexamine which is a hazardous chemical to handle. In~te~d, we have relied on chemicals already used in the conventional rubber manufacturing process.
30 Our discovery essentially coll-plises of the use of a chemical paste which is capable of initiating proton exchange in a controlled manner at lell~pel~lures below 40C and thereby open up or delink the vulcanised network of elastomeric material, preferably the chemical paste co-llplises zinc salt of dimethydithiocarbamate (hereinafter "ZDC") and mercaplobenzothiazole (hereinafter "MBT"), in the molar ratio in the range of 1:1 to 1:12 dispersed in a diol, preferably diethylene glycol, and in the presence of stearic acid, zinc oxide and sulphur. This mixture, which may be termed the 'paste', when blended with tyre crumbs or any other vulcanised crumbs in concenlr~lions of prerel~bly 6 parts paste per 100 5 parts of rubber crumbs on a mill effectively delinks the vulcanised network and renders the compound ready for moulding and vulc~ni7~tion. The total milling period, which occurs at tempel~lures below 40C, takes only 7 to 10 minlltes. Alternatively, the binder and tyre crumbs could be first mixed in an intermix and subsequently milled in an open mill.
o We have also developed a more convenient method of h~n~ling the chemicals of the paste, i.e. by the master batch method. The paste chemicals are first mixed with fresh or vulcanised rubber in the proportion of paste:rubber ratios of between 90:10 to 40:60. This master batch mixture can be mixed with vulcanised crumbs in proportions which will ensure that the ultimate ratio of binder:rubber is 6:100. Parts are parts by weight.
Some embodiments of the invention will now be described, by way of illustration, with reference to the following Examples and Tables, and the propel lies of the ensuing compounds illustrate the manner in which this invention is effective in practice.
Example 1 The following materials are mixed in the given proportions:-1. 2-mercaptobenzothiazol (MBT) 20.0 2. Zinc dimethyldithiocarbamate (ZDC)6.0 3. Stearic acid 2.0 4. Zinc oxide 2.0 5. Sulphur 1.5 6. Diethylene glycol 12.0 The powders are first i~ ely mixed with vigorous stirring and then the diethylene glycol added to render the whole mixture into a smooth paste.
500 g of tyre crumbs are milled in a 2 roll mill for 3 minu~e and then 15 g of the binder added. After further milling for 2 minutes another 15 g of the binder is introduced. The final 2 minutes of milling are carried out at narrow nip. By this time, it is possible to sheet ~134186 out the compound which is ready for vulc~ni7~tion at 150C for 15 to 30 minutes.Properties of the vulc~ni.~tes using tyre crumbs originating from Malaysia and Europe are shown in Table 1 below.
Table 1 CHARACTERISTICS OF VULCANISATES
prepared from tyre crumbs of 100% natural rubber Country of origin Malaysia Europe Chdl dcL~ Lics 1 2 3 4 1. Size (mm) 0.1 - 0.5 0.1 - 0.1 - 0.5 > 1.0 0.5 2. Binder content 6 6 6 6 (parts per hundred of crumb) 3. Vl,lranicn~ion (C) 143 155 143 143 4. Mooney viscosity, M,100 68 68 75 120 5. Stress at 100% elongation (MPa) 3 3 3.5 5.5 6. Tensile strength (MPa) 12.1 12.7 14.5 16 7. Elongation at break (%) 350 350 375 400 8. Elongation set (%) 15 15 15 12 9. Relative concenLIdLion of chains, 1.1 1.2 1.2 1.3 Vrelx104 (mole/cm3)*
10. High elastic component of creep, A x103 0.5 0.5 0.4 0.4 (MPa) (aO= 0.8MPa)**
* Vre, was c~lc~ tPd from the Mooney-Rivlin equation: Vre, = E
2s RT (A - 1/1~2) where E is strain;
~ is the degree of elongation;
R is the gas constant; and T is Le~ )eldLule ** Creep was calculated as follows: D(a, T) = Do (a, T) + A (~, T) log~ + T/rl (~, T) where D is strain (%), Do is the initial strain at ~ = 1 min (%);
A is the rate constant of creep of high elastic strain (1/MPa);
77 is viscosity (Pa-s) 3s ~13~18~
-Example 2 The paste described in Example 1 in this case is incorporated into tyre crumbs and pelletised used gloves, again in the proportion of binder:vulcanised crumbs at 6:100. The s mastic~ti~tion and binder incorporation process are as described in Example 1. The mill telllpela~ule is not allowed to exceed 40C. The total milling time is kept below 10 minutes.
Table 2 below shows the plopellies obtained from tyre and glove crumbs. For colllpalison purposes the general properties obtained from fresh rubber both with (tyre compounds) and without fillers (pure gum compound) are shown in Table 2 below.
Table 2 Properties obtained from scrap tyre treads and scrap gloves S in colllpa~ison with compounds using posh rubber Material type tyre scrapfresh rubber fresh rubber scrap glove(tyre compounds)(gum compounds) Tensile strength (MPa) 13 14.5 18 - 21 21 - 23 Elongation (%) 300 900 350 - 500 700 - 800 Elongation set (%) 10 15 Relative concellllalion of 1.4 0.6 chains, Vrd x103 (mole/cm3) Example 3 In this Example, the paste (as described in Example 1) is admixed with fresh rubber, tyre crumbs and glove crumbs to obtain master batches cont~ining 90% paste and 50% paste.
The master batches so produced are then incorporated separately into tyre crumbs and glove 35 crumbs in the manner described under Example 1, except that, in the case of the 90% paste master batch, 6.6 parts of the master batch is used for 100 parts of vulcanised crumbs and for the 50% master batch, 12 parts per 100 of crumbs are employed. The resultantproperties are shown in Table 3.
213~18~
Table 3 ~lupe-~ies obtained using binder master batches Type offresh NR: paste NR: pasteGloves: pasteGloves: paste S . a~ l,al~ ll10:90 50:50 10:90 50:50 V~ q~ PA scrap:tyre gloves tyre gloves tyre gloves tyre gloves tread tread tread tread Tensile strength11.5 17 11 10 10 13.5 12 10.5 (MPa) F~ ;, on (%) 250 860 250 610 250 780 320 600 Flonga~ion set (%) 5 10 6 15 10 10 6 15 Relative co~ ion 1.3 0.7 1.3 0.6 1.2 0.6 1.3 0.6 of chains, V"" x104 (mole/cm3) The above examples are illustrative of the versatility and effectiveness of the process of the present invention to provide recycled rubber compounds from used NR, SR and NR
combination and SR vulci~ni.~i~tes. The resultant recycled rubber compounds display satisfactory level of physical and dynamic characteristics. Such compounds can be directly 20 used in moulded goods or in admixture with fresh compounds in tyres and related areas. The master batching process can be further refined with use of SBR in place of NR. With careful control of the binder incorporation process, the milling process and temperature during mastication, the resultant physical and dynamic characteristics of the final recycled compound from tyre and glove wastes can be further enhanced.
The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the scope of the invention.
There are described above novel features which the skilled person in the art will appreciate give rise to advantages. It is to be noted that in addition to or as an alternative to the use 30 of stearic acid there may be used methacrylic acid. Also in place of diethylene glycol, there `` ~134186 -may be used propylene glycol, dipropylene glycol or triethylene glycol as well as other suitable diols which can be identified by simple experimentation.
These are each independent aspects of the invention to be covered by the present invention, 5 irrespective of whether or not they are included within the scope of the following claims.
For example, the ingredients of the "paste" of Example 1 may be varied by plus or minus 20%, preferably by plus or minus 10%.
It is to be noted that the invention also includes the composition described above as pastes o or master batches.
* Vre, was c~lc~ tPd from the Mooney-Rivlin equation: Vre, = E
2s RT (A - 1/1~2) where E is strain;
~ is the degree of elongation;
R is the gas constant; and T is Le~ )eldLule ** Creep was calculated as follows: D(a, T) = Do (a, T) + A (~, T) log~ + T/rl (~, T) where D is strain (%), Do is the initial strain at ~ = 1 min (%);
A is the rate constant of creep of high elastic strain (1/MPa);
77 is viscosity (Pa-s) 3s ~13~18~
-Example 2 The paste described in Example 1 in this case is incorporated into tyre crumbs and pelletised used gloves, again in the proportion of binder:vulcanised crumbs at 6:100. The s mastic~ti~tion and binder incorporation process are as described in Example 1. The mill telllpela~ule is not allowed to exceed 40C. The total milling time is kept below 10 minutes.
Table 2 below shows the plopellies obtained from tyre and glove crumbs. For colllpalison purposes the general properties obtained from fresh rubber both with (tyre compounds) and without fillers (pure gum compound) are shown in Table 2 below.
Table 2 Properties obtained from scrap tyre treads and scrap gloves S in colllpa~ison with compounds using posh rubber Material type tyre scrapfresh rubber fresh rubber scrap glove(tyre compounds)(gum compounds) Tensile strength (MPa) 13 14.5 18 - 21 21 - 23 Elongation (%) 300 900 350 - 500 700 - 800 Elongation set (%) 10 15 Relative concellllalion of 1.4 0.6 chains, Vrd x103 (mole/cm3) Example 3 In this Example, the paste (as described in Example 1) is admixed with fresh rubber, tyre crumbs and glove crumbs to obtain master batches cont~ining 90% paste and 50% paste.
The master batches so produced are then incorporated separately into tyre crumbs and glove 35 crumbs in the manner described under Example 1, except that, in the case of the 90% paste master batch, 6.6 parts of the master batch is used for 100 parts of vulcanised crumbs and for the 50% master batch, 12 parts per 100 of crumbs are employed. The resultantproperties are shown in Table 3.
213~18~
Table 3 ~lupe-~ies obtained using binder master batches Type offresh NR: paste NR: pasteGloves: pasteGloves: paste S . a~ l,al~ ll10:90 50:50 10:90 50:50 V~ q~ PA scrap:tyre gloves tyre gloves tyre gloves tyre gloves tread tread tread tread Tensile strength11.5 17 11 10 10 13.5 12 10.5 (MPa) F~ ;, on (%) 250 860 250 610 250 780 320 600 Flonga~ion set (%) 5 10 6 15 10 10 6 15 Relative co~ ion 1.3 0.7 1.3 0.6 1.2 0.6 1.3 0.6 of chains, V"" x104 (mole/cm3) The above examples are illustrative of the versatility and effectiveness of the process of the present invention to provide recycled rubber compounds from used NR, SR and NR
combination and SR vulci~ni.~i~tes. The resultant recycled rubber compounds display satisfactory level of physical and dynamic characteristics. Such compounds can be directly 20 used in moulded goods or in admixture with fresh compounds in tyres and related areas. The master batching process can be further refined with use of SBR in place of NR. With careful control of the binder incorporation process, the milling process and temperature during mastication, the resultant physical and dynamic characteristics of the final recycled compound from tyre and glove wastes can be further enhanced.
The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the scope of the invention.
There are described above novel features which the skilled person in the art will appreciate give rise to advantages. It is to be noted that in addition to or as an alternative to the use 30 of stearic acid there may be used methacrylic acid. Also in place of diethylene glycol, there `` ~134186 -may be used propylene glycol, dipropylene glycol or triethylene glycol as well as other suitable diols which can be identified by simple experimentation.
These are each independent aspects of the invention to be covered by the present invention, 5 irrespective of whether or not they are included within the scope of the following claims.
For example, the ingredients of the "paste" of Example 1 may be varied by plus or minus 20%, preferably by plus or minus 10%.
It is to be noted that the invention also includes the composition described above as pastes o or master batches.
Claims (14)
1. A process of recycling used sulphur-cured elastomeric material comprising masticating the said elastomeric materials at temperatures below 40°C with a chemical paste which is capable of initiating proton exchange in a controlled manner at temperatures below 40°C and thereby open up or delink the vulcanised network of the elastomeric materials.
2. A process according to Claim 1 wherein the chemical paste comprises zinc dimethyldithiocarbamate and 2-mercaptobenzothiazole in the respective molecular proportion within the range of about 1:1 to 1:12.
3. A process according to Claim 2 wherein the chemical paste is activated by a diol in the presence of stearic acid, zinc oxide and sulphur.
4. A process according to Claim 3 wherein the diol is diethylene glycol.
5. A process according to any one of the preceding claims wherein a master batch of the mixture of the chemical paste and used elastomeric materials is made in the ratio of chemical binder:elastomeric materials in the range of about 40:60 to 90:10.
6. A process according to Claim 1 wherein the said chemical paste is mixed with the said elastomeric material in the respective proportion of about 6 parts per 100 parts.
7. A process according to Claim 6 wherein the master batch of Claim 5 is used and the proportion of the master batch:elastomeric material is adjusted accordingly to achieve the ratio of paste:elastomeric materials of 6:100.
8. A process according to Claim 1 wherein the used elastomeric material is made of natural rubber, synthetic rubber or blends thereof vulcanised with the conventional sulphur curing system.
9. A process according to Claim 1 wherein the sulphur-cured elastomer materials are in crumbs form amenable for recycling from a wide range of moulded or extruded rubber products.
10. A process as claimed in any one of the preceding claims, wherein a product is produced through fabrication, moulding and/or vulcanisation.
11. A composition which is capable of opening up or delinking the vulcanised network of sulphur-cured elastomeric material which comprises zinc dimethyldithiocarbamate and 2-mercaptobenzothiazole in the respective molecular proportion within the range of about 1:1 to 1:12.
12. A composition as claimed in Claim 11, which is activated by a diol in the presence of stearic acid, zinc oxide and sulphur.
13. A composition as claimed in Claim 12, wherein the diol is diethylene glycol.
14. A composition as claimed in any one of Claims 11 to 13, which is a mixture of the ingredients of the composition together with used sulphur-cured elastomeric materials in the form of a master batch in the ratio of the defined composition:elastomeric material of about 40:60 to 90:10.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| MYPI9401654 | 1994-06-25 | ||
| MYPI9401654 | 1994-06-25 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2134186A1 true CA2134186A1 (en) | 1995-12-26 |
Family
ID=19749697
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2134186 Abandoned CA2134186A1 (en) | 1994-06-25 | 1994-10-24 | Recycling of natural and synthetic rubber |
Country Status (8)
| Country | Link |
|---|---|
| KR (1) | KR100386192B1 (en) |
| CN (1) | CN1118791A (en) |
| CA (1) | CA2134186A1 (en) |
| MD (1) | MD1369C2 (en) |
| RU (1) | RU2219199C2 (en) |
| TR (1) | TR199500909A2 (en) |
| TW (1) | TW289026B (en) |
| ZA (1) | ZA955284B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9683088B2 (en) | 2012-08-31 | 2017-06-20 | Continental Reifen Deutschland Gmbh | Process for regenerating sulfur-crosslinked rubber vulcanizates to give regenerates |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR101967451B1 (en) | 2016-11-17 | 2019-04-10 | 주식회사 남명 | Composite molding method using ethylene-propylene rubber waste scrap and waste fiber |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4211676A (en) * | 1977-06-07 | 1980-07-08 | Bridgestone Tire Company Limited | Process for reclaiming scrap vulcanized rubber |
| SU956297A1 (en) * | 1981-03-27 | 1982-09-07 | Ярославский политехнический институт | Rubber disintegration method |
| SU1620454A1 (en) * | 1987-07-13 | 1991-01-15 | Предприятие П/Я А-3832 | Composition for producing regenerate |
-
1994
- 1994-10-24 CA CA 2134186 patent/CA2134186A1/en not_active Abandoned
- 1994-11-03 CN CN94113887A patent/CN1118791A/en active Pending
-
1995
- 1995-03-22 TW TW84102803A patent/TW289026B/zh active
- 1995-06-02 KR KR1019950014575A patent/KR100386192B1/en not_active IP Right Cessation
- 1995-06-23 RU RU95110768A patent/RU2219199C2/en not_active IP Right Cessation
- 1995-06-26 MD MD95-0371A patent/MD1369C2/en unknown
- 1995-06-26 ZA ZA955284A patent/ZA955284B/en unknown
- 1995-07-27 TR TR95/00909A patent/TR199500909A2/en unknown
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9683088B2 (en) | 2012-08-31 | 2017-06-20 | Continental Reifen Deutschland Gmbh | Process for regenerating sulfur-crosslinked rubber vulcanizates to give regenerates |
Also Published As
| Publication number | Publication date |
|---|---|
| KR100386192B1 (en) | 2003-08-09 |
| TW289026B (en) | 1996-10-21 |
| CN1118791A (en) | 1996-03-20 |
| RU2219199C2 (en) | 2003-12-20 |
| MD1369C2 (en) | 2000-11-30 |
| RU95110768A (en) | 1997-05-10 |
| MD1369B2 (en) | 1999-12-31 |
| TR199500909A2 (en) | 1997-03-21 |
| ZA955284B (en) | 1996-12-27 |
| KR960000979A (en) | 1996-01-25 |
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