FORM 2
THE PATENTS ACT, 1970 (39 of 1970) & THE PATENTS RULES, 2003
COMPLETE SPECIFICATION (See section 10, rule 13)
1. Title of the invention: A PROCESS FOR RECOVERING ELASTOMERS FROM
RUBBER COMPOUND
2. Applicant(s)
NAME NATIONALITY ADDRESS
CEAT LIMITED Indian RPG HOUSE, 463, Dr. Annie Besant Road, Worli, Mumbai, Maharashtra 400030, India
3. Preamble to the description
COMPLETE SPECIFICATION
The following specification particularly describes the invention and the manner in which it
is to be performed.

FIELD OF INVENTION
[0001] The subject matter described herein relates to a process for recovering elastomers. Particularly, the present disclosure relates to a process for recovering elastomers from cured or uncured rubber compounds.
BACKGROUND OF THE INVENTION
[0002] From the point of energy consumption, economic advantages and environmental issues, polymer recycling is the most efficient way to manage waste materials. In the case of rubber recycling, the waste rubber can go through size reduction, and the resulting powders can be melted, and blended with thermoplastic resins to produce recycled thermoplastic elastomer (TPE) compounds. However, the recovery of elastomers from rubber compounds faces challenges in the aspects of degradation during the digestion process, and high processing parameters.
[0003] To recover or separate elastomers from rubber compounds the traditionally available technique is the solvent digestion method which uses a heating mantel and requires a minimum of 10 hours to separate elastomers from rubber compounds. Further, the solvent consumption is also very high to recover elastomers from 1 gm of rubber compound sample and the method also required organic solvents such as dichlorobenzene.
[0004] Therefore, there is a need to develop a rapid process for recovering elastomers from rubber compounds with reduced solvent consumption, and having efficiency independent of the quantity of rubber compound.
SUMMARY OF THE INVENTION
[0005] In an aspect of the present disclosure, there is provided a process for recovering elastomers from an uncured or cured rubber compound, the process comprising: a. irradiating the rubber compound in presence of a solvent with a microwave radiation at a power in a range of 800 to 2000W for a period in a range of 20 to 40 minutes to obtain a first mixture; b. maintaining the first mixture at 210 to 230 °C for a period in a range of 50 minutes to 120 minutes to obtain a second mixture; and irradiating the second mixture with a microwave radiation at a power

in a range of 800 to 2000W for a period in a range of 5 minutes to 15 minutes to recover the elastomers from the rubber compound.
[0006] In another aspect of the present disclosure, there is provided a use of the process as disclosed herein, for quantitative and qualitative analysis of the elastomer content in a rubber compound.
[0007] In yet another aspect of the present disclosure, there is provided a method for quantitative analysis of elastomers, comprising: determining the amount of elastomers recovered by the process as disclosed herein.
[0008] These and other features, aspects, and advantages of the present subject matter will be better understood with reference to the following description and appended claims. This summary is provided to introduce a selection of concepts in a simplified form. This summary is not intended to identify key features or essential features of the disclosed subject matter, nor is it intended to be used to limit the scope of the disclosed subject matter.
BRIEF DESCRIPTION OF DRAWINGS
[0009] In order that the disclosure may be readily understood and put into practical effect, reference will now be made to exemplary embodiments as illustrated with reference to the accompanying figures. The figures together with a detailed description below, are incorporated in and form part of the specification, and serve to further illustrate the embodiments and explain various principles and advantages, in accordance with the present disclosure.
[0010] Figure 1 depicts the Fourier transform infrared (FTIR) graph of the recovered elastomer for the (a) Sample-1; (b) Sample-2; (c) Sample-3; (d) Sample-4; and (e) Sample-5 recovered by the (i) process of present invention and (ii) conventional electric heating mantle process, in accordance with an embodiment of the present disclosure.
DETAILED DESCRIPTION OF THE INVENTION
[0011] Those skilled in the art will be aware that the present disclosure is subject
to variations and modifications other than those specifically described. It is to be

understood that the present disclosure includes all such variations and modifications. The disclosure also includes all such steps, features, compositions, and compounds referred to or indicated in this specification, individually or collectively, and any and all combinations of any or more of such steps or features.
Definitions
[0012] For convenience, before further description of the present disclosure, certain terms employed in the specification, and examples are delineated here. These definitions should be read in the light of the remainder of the disclosure and understood as by a person of skill in the art. The terms used herein have the meanings recognized and known to those of skill in the art, however, for convenience and completeness, particular terms and their meanings are set forth below.
[0013] The articles "a", "an" and "the" are used to refer to one or to more than one (i.e., to at least one) of the grammatical object of the article.
[0014] The terms "comprise" and "comprising" are used in the inclusive, open sense, meaning that additional elements may be included. It is not intended to be construed as "consists of only".
[0015] Throughout this specification, unless the context requires otherwise the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated element or step or group of elements or steps but not the exclusion of any other element or step or group of elements or steps.
[0016] The term "including" is used to mean "including but not limited to". "including" and "including but not limited to" are used interchangeably.
[0017] The term “microwave radiation” refers to the electromagnetic radiation having wavelength between 1mm and 1m. In an aspect of the present disclosure, there is provided a process for recovering elastomers from cured or uncured rubber compound, the process comprising: irradiating the rubber compound in presence of a solvent with a microwave radiation at 210 to 230 °C for a period in a range of 20

to 40 minutes. In another aspect of the present disclosure, the irradiation is carried out at a power in a range of 800 to 2000W.
[0018] Ratios, concentrations, amounts, and other numerical data may be presented herein in a range format. It is to be understood that such range format is used merely for convenience and brevity and should be interpreted flexibly to include not only the numerical values explicitly recited as the limits of the range but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. For example, a range of 0.1 to 10% should be interpreted to include not only the explicitly recited limits of 0.1% to 10% but also to include sub-ranges, such as 0.1 to 1.9%, 3 to 8%, and so forth, as well as individual amounts, within the specified ranges, such as 1%, 2.5%, 3.5%, 5% and 10% for example.
[0019] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the disclosure, the preferred methods, and materials are now described. All publications mentioned herein are incorporated herein by reference.
[0020] The present disclosure is not to be limited in scope by the specific embodiments described herein, which are intended for the purposes of exemplification only. Functionally equivalent products, compositions, and methods are clearly within the scope of the disclosure, as described herein.
[0021] As discussed in the background, the conventional electric mantle heating digestion processes for recovery of elastomers consume large amount of solvent and time in a range of 10 to 15 hours. Microwave digestion is considered as not suitable for rubber extraction because this technique is regarded to cause structural disintegration. Meanwhile, though the other conventional technique of electric mantle heating digestion of elastomer maintains structural integrity using metal but requires more time and higher quantity of samples and solvent. As a solution to the

problems in the traditional processes of recovery, the process disclosed in the present disclosure employs multistep microwave radiation for the recovery of elastomers from rubber compound.
[0022] The process of the present disclosure facilitates the separation of elastomer from cured or uncured rubber compound comprising antioxidants such as amine, or quinoline, reinforcements such as sulfur, fillers such as carbon black, or silica, activators such as zinc oxide, accelerators such as sulphenamide, thiuram, or diphenyl guanidine, processing aids such as oil or wax, activator, resin and other plasticizers. The process disclosed in the present disclosure employs subjecting the rubber compound to stepwise microwave radiation within less time, using lower amounts of solvent and sample for extraction wherein the structural integrity of the obtained elastomer is maintained. Furthermore, the process of the present disclosure takes only 2 to 3 hours for the recovery process, with less solvent and with minimum quantity of rubber compound.
[0023] Accordingly, in an embodiment of the present disclosure, there is provided a process for recovering elastomers from an uncured or cured rubber compound, the process comprising: a. irradiating the rubber compound in presence of a solvent with a microwave radiation at a power in a range of 800 to 2000W for a period in a range of 20 to 40 minutes to obtain a first mixture; b. maintaining the first mixture 210 to 230 °C for a period in a range of 50 minutes to 120 minutes to obtain a second mixture; and irradiating the second mixture with a microwave radiation at a power in a range of 800 to 2000W for a period in a range of 5 minutes to 15 minutes to recover the elastomers from the rubber compound.
[0024] In another embodiment of the present disclosure, there is provided a process for recovering elastomers from an uncured or cured rubber compound, the process comprising: a. irradiating the rubber compound in presence of a solvent with a microwave radiation at 210 to 230 °C for a period in a range of 20 to 40 minutes to obtain a first mixture; b. maintaining the first mixture at 210 to 230 °C for a period in a range of 50 minutes to 120 minutes to obtain a second mixture; and irradiating

the second mixture to obtain elastomers at 60 to 80 °C for a period in a range of 5 minutes to 15 minutes to recover the elastomers from the rubber compound.
[0025] In another embodiment of the present disclosure, there is provided a process for recovering elastomers from an uncured or cured rubber compound, the process comprising: a. irradiating the rubber compound in presence of a solvent with a microwave radiation at 215 to 225 °C for a period in a range of 20 to 40 minutes to obtain a first mixture; b. maintaining the first mixture at 215 to 225 °C for a period in a range of 50 minutes to 120 minutes to obtain a second mixture; and irradiating the second mixture to obtain elastomers 65 to 75 °C for a period in a range of 5 minutes to 15 minutes to recover the elastomers from the rubber compound.
[0026] In yet another embodiment of the present disclosure, there is provided a process for recovering elastomers from an uncured or cured rubber compound, the process comprising: a. irradiating the rubber compound in presence of a solvent with a microwave radiation at 220 °C for a period in a range of 25 to 35 minutes to obtain a first mixture; b. maintaining the first mixture at 220 °C for a period in a range of 55 minutes to 100 minutes to obtain a second mixture; and irradiating the second mixture to obtain elastomers 70 °C for a period in a range of 8 minutes to 12 minutes to recover the elastomers from the rubber compound.
[0027] In another embodiment of the present disclosure, there is provided a process for recovering elastomers from an uncured or cured rubber compound, the process comprising: a. irradiating the rubber compound in presence of a solvent with a microwave radiation at 220 °C for a period in a range of 20 to 40 minutes to obtain a first mixture; b. maintaining the first mixture at 220 °C for a period in a range of 50 minutes to 120 minutes to obtain a second mixture; and irradiating the second mixture to obtain elastomers 70 °C for a period in a range of 5 minutes to 15 minutes to recover the elastomers from the rubber compound. In another embodiment of the present disclosure, there is provided a process for recovering elastomers from an uncured or cured rubber compound, the process comprising: a. irradiating the rubber compound in presence of a solvent with a microwave radiation at 220 °C for a period in a range of 25 to 35 minutes to obtain a first mixture; b. maintaining the

first mixture at 220 °C for a period in a range of 55 minutes to 100 minutes to obtain a second mixture; and irradiating the second mixture to obtain elastomers 70 °C for a period in a range of 8 minutes to 12 minutes to recover the elastomers from the rubber compound. In yet another embodiment of the present disclosure, there is provided a process for recovering elastomers from an uncured or cured rubber compound, the process comprising: a. irradiating the rubber compound in presence of a solvent with a microwave radiation at 220 °C for a period of 30 minutes to obtain a first mixture; b. maintaining the first mixture at 220 °C for a period of 60 minutes to obtain a second mixture; and irradiating the second mixture to obtain elastomers 70 °C for a period of 10 minutes to recover the elastomers from the rubber compound.
[0028] In an embodiment of the present disclosure, there is provided a process as disclosed herein, wherein the step (c) further comprises processing the second mixture to recover the elastomers of the rubber compound; and the processing is selected from sedimentation, filtration, or combinations thereof.
[0029] In an embodiment of the present disclosure, there is provided a process as disclosed herein, wherein the steps (a), (b), and (c) are carried out while stirring at a speed in a range of 200 to 1200rpm. In another embodiment of the present disclosure, the steps (a), (b), and (c) are carried out while stirring at a speed in a range of 500 to 1000rpm.
[0030] In an embodiment of the present disclosure, there is provided a process as disclosed herein, wherein the microwave radiation is irradiated at a power in a range of 800 to 2000W. In another embodiment of the present disclosure, the microwave radiation is irradiated at a power in a range of 1000 to 1900W. In yet another embodiment of the present disclosure, the microwave radiation is irradiated at a power of 1800W.
[0031] In an embodiment of the present disclosure, there is provided a process as disclosed herein, wherein the process is carried out at a pressure in a range of 15 to 35 bar. In another embodiment of the present disclosure, the process is carried out

at a pressure in a range of 16 to 30 bar. In yet another embodiment of the present disclosure, the process is carried out at a pressure of 18 bar.
[0032] In an embodiment of the present disclosure, there is provided a process as disclosed herein, wherein the solvent is selected from dichlorobenzene, toluene, or combinations thereof. In another embodiment of the present disclosure, the solvent is dichlorobenzene.
[0033] In an embodiment of the present disclosure, there is provided a process as disclosed herein, wherein the rubber compound is in a weight range of 0.1 to 10%, with respect to the total volume of the solvent. In another embodiment of the present disclosure, the rubber compound is in a weight range of 0.5 to 5%, with respect to the total volume of the solvent. In yet another embodiment of the present disclosure, the rubber compound is in a weight range of 1 to 3%, with respect to the total volume of the solvent. In yet another embodiment of the present disclosure, the rubber compound is in a weight of 2%, with respect to the total volume of the solvent.
[0034] In an embodiment of the present disclosure, there is provided a process as disclosed herein, wherein the rubber compound is subjected to processes selected from crushing, grinding, washing, drying, or combinations thereof, prior to irradiating.
[0035] In an embodiment of the present disclosure, there is provided a process as disclosed herein, wherein the elastomer obtained comprises at least one of isoprene rubber, or natural rubber. In another embodiment of the present disclosure, the elastomer obtained comprises natural rubber.
[0036] In an embodiment of the present disclosure, there is provided a process as disclosed herein, wherein the rubber compound comprises antioxidant, reinforcements, filler, accelerator, processing aids, activator, plasticizer, or combinations thereof. In another embodiment of the present disclosure, the rubber compound comprises antioxidants selected from amine, quinoline or combinations thereof; reinforcements selected from carbon black, silica or combinations thereof;

fillers selected from clay, calcium carbonate, or combinations thereof; accelerator selected from sulphenamide, thiuram, diphenyl guanidine or combinations thereof; and an activator selected from zinc oxide, stearic acid or combinations thereof; processing aids selected from oil, wax or combinations thereof.
[0037] In an embodiment of the present disclosure, there is provided a process as disclosed herein, wherein filtration is carried out using an asbestos filtration bed.
[0038] In an embodiment of the present disclosure, there is provided a use of the process as disclosed herein, for quantitative and qualitative analysis of the elastomer content in a rubber compound.
[0039] In an embodiment of the present disclosure, there is provided a method for quantitative analysis of elastomers, comprising: determining the amount of elastomers recovered by the process as disclosed herein.
[0040] Although the subject matter has been described with reference to specific embodiments, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as alternate embodiments of the subject matter, will become apparent to persons skilled in the art upon reference to the description of the subject matter. It is therefore contemplated that such modifications can be made without departing from the spirit or scope of the present subject matter as defined.
EXAMPLES
[0041] The disclosure will now be illustrated with the working examples, which is intended to illustrate the working of disclosure and not intended to take restrictively to imply any limitations on the scope of the present disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one ordinary person skilled in the art to which this disclosure belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice of the disclosed methods and compositions, the exemplary methods, devices, and materials are described herein.

It is to be understood that this disclosure is not limited to particular methods, and experimental conditions described, as such methods and conditions may apply.
Materials and Methods
[0042] For the purpose of the present disclosure, the following materials were
employed.
[0043] Rubber compound, dichlorobenzene (AR / LR grade, Make - Merck),
[0044] Instrument used for microwave radiation is Anton paar - Multiwave 5000.
[0045] Instrument used for fourier transform infrared (FTIR) analysis is Perkin elmer - Spectrum 100.
EXAMPLE 1
Process of recovering elastomers
[0046] About 0.5 g of a rubber compound containing natural rubber, synthetic rubber and other additives such as antioxidants, reinforcements, filler, accelerator, processing aids, activator, and plasticizer was crushed and dispersed in 25mL dichlorobenzene solvent to obtain a mixture. The mixture was irradiated with a microwave radiation at 220 °C under stirring at 1000rpm for a period of 30 minutes at a power of 1800W to obtain a first mixture. The first mixture was maintained at 220 °C for a period of 120 minutes to obtain a second mixture. The second mixture was irradiated with microwave radiation at 70 °C for a period of 10 to 15 minutes and then subjected to sedimentation, filtration using an asbestos powder filtration bed to recover the elastomers from the rubber compound. The whole process of recovery was conducted at a pressure of 30bar.
[0047] Different cured and uncured natural rubber compounds were processed by the process as explained above to obtain elastomers in better amounts. Further, for comparative purposes, the same sample was subjected to electric heating mantle technique denoted as conventional process herein. In the conventional process, minimum 1 gm of rubber compound sample was required and said 1 gm rubber compound sample was to be dispersed in 50 ml of dichlorobenzene solvent followed by digesting at 175°C for 12 hours to obtain a mixture. The mixture was

then filtered in Gooch crucible using asbestos filter bed to recover polymer from digested solution.The amounts of yielded elastomers natural rubber (NR), butadiene rubber (BR), and styrene butadiene rubber (SBR), are comparatively tabulated below in Table 1 for each rubber compound samples. [0048] Table 1

SAMPLE-1
Elastomer Process of
present disclosure
(weight %) Conventional
process (weight %)
NR 41.15 39.7
BR 33.95 35.09
SBR 24.9 25.21

SAMPLE-2
Elastomer Process of
present disclosure
(weight %) Conventional
process (weight %)
NR 25.9 21.7
BR 40 41.33
SBR 34.1 36.97

SAMPLE-3
Elastomer Process of
present disclosure
(weight %) Conventional
process (weight %)
NR 72.76 78.22
BR 0 0
SBR 27.24 21.78

SAMPLE-4
Elastomer Process of
present disclosure
(weight %) Conventional
process (weight %)
NR 76.02 73.61
BR 0 0
SBR 23.98 26.39
SAMPLE-5

Elastomer Process of
present disclosure
(weight %) Conventional
process
(weight %)
NR 60.04 57.55
BR 0 0
SBR 39.96 42.45
[0049] Hence, it was evident that in addition to the added advantage of reduced time consumption and less solvent wastage, the present disclosure provides better yields of the specific elastomer of natural rubber in comparison to the conventional process for each of the analyzed rubber compound samples. Samples 1 to 5 are different tire component samples, where Samples 1 and 2 are tread cap rubber compound, Samples 3 and 4 are bead filler rubber compounds, sample 5 is inner liner compound. Therefore, irrespective of the different polymer ratio and filler ratio in different samples, the recovery of polymer was almost complete when the process of the present disclosure was employed. Furthermore, the process of the present disclosure provided recovery of elastomer in higher yields even when a very small amount of the rubber compound sample was taken. Lastly, the process also showed scalability to higher extend due to the lesser number of parameters in the process which were also conveniently optimizable.
[0050] The obtained elastomers were analyzed using Fourier transform infrared (FTIR) spectroscopy to confirm that there was not any structural disintegration, and the elastomers were completely recovered from the rubber compound irrespective of whether the rubber compound was cured or uncured. Figure 1 depicts the Fourier transform infrared (FTIR) graph of the recovered elastomer for the (a) Sample-1; (b) Sample-2; (c) Sample-3; (d) Sample-4; and (e) Sample-5 recovered by the (i) process of present invention and (ii) conventional electric heating mantle process. The peaks observed at 1375 & 835 cm-1 corresponded to natural rubber; peaks observed at 725 to 740 cm-1 corresponded to butadiene rubber; and the peak that was observed at699 cm-1 corresponded to styrene peak of styrene butadiene rubber.
ADVANTAGES OF THE PRESENT DISCLOSURE

[0051] The process for recovery of elastomers as provided in the present disclosure employs less amount of solvent and less time for recovery process. The process of the present disclosure also provides elastomer yields without structural disintegration even by using the microwave irradiation.

I/We Claim:
1. A process for recovering elastomers from an uncured or cured rubber
compound, the process comprising:
a. irradiating the rubber compound in presence of a solvent with a
microwave radiation at a power in a range of 800 to 2000W for a period
in a range of 20 to 40 minutes to obtain a first mixture;
b. maintaining the first mixture at 210 to 230 °C for a period in a range of
50 minutes to 120 minutes to obtain a second mixture; and
c. irradiating the second mixture with a microwave radiation at a power in
a range of 800 to 2000W for a period in a range of 5 to 15 minutes to
recover the elastomers from the rubber compound.
2. The process as claimed in claim 1, wherein the step (c) further comprises processing the second mixture to recover the elastomers of the rubber compound; and the processing is selected from sedimentation, filtration, or combinations thereof.
3. The process as claimed in claim 1, wherein the steps (a), (b), and (c) are carried out while stirring at a speed in a range of 200 to 1200rpm.
4. The process as claimed in claim 1, wherein the steps (a), (b) and (c) are irradiated with the microwave radiation at 210 to 230 °C and at 60 to 80 °C, respectively.
5. The process as claimed in claim 1, wherein the process is carried out at a pressure in a range of 15 to 35 bar.
6. The process as claimed in claim 1, wherein the solvent is selected from dichlorobenzene, toluene, or combinations thereof.
7. The process as claimed in claim 1, wherein the rubber compound is in a weight range of 0.1 to 10%, with respect to the total volume of the solvent.
8. The process as claimed in claim 1, wherein the rubber compound is subjected to processes selected from crushing, grinding, washing, drying, or combinations thereof, prior to irradiating.

9. The process as claimed in claim 1, wherein the elastomer obtained comprises at least one of diene rubber, styrene rubber, vinyl rubber, isoprene rubber, or natural rubber.
10. The process as claimed in claim 1, wherein the rubber compound comprises antioxidant, reinforcements, filler, accelerator, processing aids, activator, plasticizer, or combinations thereof.
11. The process as claimed in claim 2, wherein filtration is carried out using an glass fiber or asbestos filtration bed.
12. Use of the process as claimed in claim 1, for quantitative and qualitative analysis of the elastomer content in a rubber compound.
13. A method for quantitative analysis of elastomers, comprising:
a. determining the amount of elastomers recovered by the process as claimed in claim 1.