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 METHOD FOR DEVULCANZATION OF RUBBER
2. Applicant(s)
NAME NATIONALITY ADDRESS
CEAT LIMITED Indian RPG HOUSE, 463, Dr. Annie Besant Road, Worli, Mumbai, Maharashtra 400 030, 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 the field of rubber and in particular relates to the devulcanized rubber, and a method for devulcanization thereof.
BACKGROUND OF THE INVENTION
[0002] Scrapped vulcanized rubber is threat for the environment as it is not biodegradable. Also discarded worn out tires are non-biodegradable material. Further, due to its three-dimensional crosslinked network structure, the natural degradation requires long duration. It also causes two serious problems, environmental pollution and wastage of a valuable rubber. The main approach to solve this problem is de-vulcanization and reuse of used and waste tire. Devulcanization of vulcanized rubber is well known process. However, recycling of used or waste tires or ay rubber related products, by devulcanization has proven to face extremely challenging problem(s), mainly in terms of the fact that in the vulcanized rubber that generates a cross-linking of the polymers or elastomer with sulfur. The resulting cross-linked rubber being a thermoset prevent the cross-linked rubber from melting and thereby make it harder to be converted to other desired material. Also, the reclaimed or devulcanized rubber obtained from market has disadvantages such as it is made from mixture of all type of rubber products, thereby lacks homogeneity and consistency in properties and the process adopted by reclaim manufactures is uncontrolled thereby breaking the C-C bonds of polymer chain along with S-S or C-S bonds.
[0003] US8961889B2 discloses devulcanization apparatus for devulcanizing a plurality of cross-linked elastomer particles comprising a first conveyor functioning as a high voltage electrode, a second conveyor functioning as a ground electrode and a generator operable to apply an alternating electric field between the first and second conveyor. CA2589307C discloses a process for the hydro-devulcanization of vulcanized rubber utilizing a rubber swelling solvent, a source of reactive hydrogen at elevated temperature and a hydrogenation catalyst.

[0004] Although a lot of attempts have been made to obtain devulcanized rubber, there is still a need in the state of art for a simple, efficient and economically viable method for devulcanization of used/vulcanized rubber is essential to obtain reclaimed/ devulcanized rubber.
SUMMARY OF THE INVENTION
[0005] In an aspect of the present disclosure, there is provided a method for
thermomechanical devulcanization of a rubber, the method comprising: a) obtaining a
vulcanized rubber; b) grinding the vulcanized rubber into rubber granules; and c)
processing the rubber granules in a co-rotating twin screw extruder to obtain a
devulcanized rubber, wherein processing the rubber granules in a co-rotating twin
screw extruder is carried out at a screw speed of 400-1000 rpm.
[0006] In another aspect of the present disclosure, there is provided a devulcanized
rubber obtained by the method comprising: a) obtaining a vulcanized rubber; b)
grinding the vulcanized rubber into rubber granules; and c) processing the rubber
granules in a co-rotating twin screw extruder to obtain a devulcanized rubber, wherein
processing the rubber granules in a co-rotating twin screw extruder is carried out at a
screw speed of 400-1000 rpm.
[0007] In one another aspect of the present disclosure, there is provided a reclaim
rubber obtained by the method comprising: a) obtaining a vulcanized rubber; b)
grinding the vulcanized rubber into rubber granules; and c) processing the rubber
granules in a co-rotating twin screw extruder to obtain a devulcanized rubber, wherein
processing the rubber granules in a co-rotating twin screw extruder is carried out at a
screw speed of 400-1000 rpm.
[0008] In yet another aspect of the present disclosure, there is provided an article
comprising the devulcanized rubber obtained by the method comprising: a) obtaining
a vulcanized rubber; b) grinding the vulcanized rubber into rubber granules; and c)
processing the rubber granules in a co-rotating twin screw extruder to obtain a

devulcanized rubber, wherein processing the rubber granules in a co-rotating twin screw extruder is carried out at a screw speed of 400-1000 rpm.
[0009] 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 claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.
BRIEF DESCRIPTION OF DRAWINGS
[0010] The detailed description is described with reference to the accompanying
figures. In the figures, the left-most digit(s) of a reference number identifies the figure
in which the reference number first appears. The same numbers are used throughout
the drawings to reference like features and components.
[0011] Figure 1 illustrates the co-rotating twin screw extruder for devulcanization of
rubber, in accordance with an implementation of the present disclosure.
DETAILED DESCRIPTION OF THE INVENTION
[0012] 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
[0013] 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.
[0014] 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.
[0015] 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".
[0016] 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 element or steps but not the exclusion of any other element or step or group of element or steps.
[0017] The term "including" is used to mean "including but not limited to". "Including" and "including but not limited to" are used interchangeably.
[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 speed in the range of about 400 to 1000 rpm should be interpreted to include not only the explicitly recited limits of about 400 rpm to about 1000 rpm but also to include sub-ranges, such as 401-999 rpm, 550-900 rpm and so forth, as well as individual amounts, within the specified ranges, such as 450rpm, and 790 rpm, 800 rpm for example.
[0019] The term "at least one" is used to mean one or more and thus includes individual components as well as mixtures/combinations.
[0020] For the purposes of the present disclosure, the term "phr" refers to parts per hundred rubber, and it is a unit well used in the field of rubber technology to define the amount of ingredients used.

[0021] The term “rpm” used herein refers to rotations/revolutions per minute, is a unit well used in the field of rubber technology to define the speed of any rotating part of the machine, in this disclosure especially a two-roll mill, Banbury mixer, an extruder machine and an underwater pelletizer.
[0022] The term “vulcanized rubber” refers to hardened rubber with higher tensile strength and elasticity.
[0023] The term “kneading block” refers to an important functional part of the co-rotating twin screw extruder and the melting process takes place in the kneading block. [0024] The term “Mooney viscosity” refers to a property of elastomers or rubbers and defined as the shearing torque resisting rotation of a rotor disk embedded in rubber or elastomer within a cylindrical cavity. It is measured by using Mooney viscometer and calculated from the torque on the rotating disc of the machine. MI is the initial Mooney viscosity whereas ML is the minimum Mooney viscosity value in the last 30 seconds before the rotor stopped. Mooney viscosity of the devulcanized rubber is measured at 100ºC.
[0025] The term “ML (1+4) @ 100ºC” (or Mooney Viscosity at 100ºC) used herein refers to conditions maintained while performing viscosity analysis on a sample of rubber or any other compound. It indicates the effect of temperature and time on the viscosity of rubber compounds. It is measured in terms of torque, required to rotate the disk embedded in the rubber/compound under specified conditions. Normally a pre¬heat period is given to the elastomer following which the disc starts to rotate. The highest viscosity is recorded initially which later starts to decrease with time and reaches its lowest value. Viscosity measured with a large rotor is twice of that measured with a small rotor. Viscosity is measured in Mooney Units (MU) denoted herein by M. With reference to present disclosure, L refers to Large rotor, 1 refers preheat time in minutes, 4 refers to time in minutes after starting the rotor at which reading is taken, and 100ºC refers to the test temperature.

[0026] The term “reclaim rubber” refers to devulcanized rubber which is a cured
rubber with lowered viscosity.
[0027] The term “thermomechanical” refers to a process involving heating of the
material and a mechanical process such as mixing, grinding, and other physical
processes. In the present disclosure, the term “thermomechanical devulcanization”
refers to the process of softening of the rubber by subjecting to grinding, heating and
processing in an extruder.
[0028] The term “co-rotating twin screw extruder” refers to an extruder having twin
screws that rotates in same direction and is used in the processing of rubber.
[0029] The term “barrel temperature” refers to the temperature in which the rubber
compound is maintained in while processing. In the present disclosure, the term “barrel
temperature” refers to the temperature at which the processing of the rubber granules
is carried out in the co-rotating twin screw extruder.
[0030] 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.
[0031] 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.
[0032] In the view of the shortcomings of the existing literature, it can be understood
that there is an increasingly dire need exists to come up with not only for a cost effective
simple devulcanization method but also to obtain devulcanized rubber with improved
properties. The present disclosure provides one such thermomechanical method for

devulcanization of a vulcanized rubber by employing a co-rotating twin screw extruder with a screw speed of 400-1000 rpm.
[0033] In an embodiment of the present disclosure, there is provided a method for thermomechanical devulcanization of a rubber, the method comprising: a) obtaining a vulcanized rubber; b) grinding the vulcanized rubber into rubber granules; and c) processing the rubber granules in a co-rotating twin screw extruder to obtain a devulcanized rubber, wherein processing the rubber granules in a co-rotating twin screw extruder is carried out at a screw speed of 400-1000 rpm.
[0034] In an embodiment of the present disclosure, there is provided a method for thermomechanical devulcanization of a rubber, the method comprising: a) obtaining a vulcanized rubber; grinding the vulcanized rubber into rubber granules; and processing the rubber granules in a co-rotating twin screw extruder to obtain a devulcanized rubber, wherein processing the rubber granules in a co-rotating twin screw extruder is carried out at a screw speed of 500-950 rpm. In another embodiment of the present disclosure, there is provided a method as described herein, wherein processing the rubber granules in a co-rotating twin screw extruder is carried out at a screw speed of 600-850 rpm. In yet another embodiment of the present disclosure, there is provided a method as described herein, wherein processing the rubber granules in a co-rotating twin screw extruder is carried out at a screw speed of 800 rpm.
[0035] In an embodiment of the present disclosure, there is provided a method for thermomechanical devulcanization of a rubber, wherein the vulcanized rubber is selected from the group consisting of natural rubber, styrene butadiene rubber, butadiene rubber, isobutene isoprene rubber and combinations thereof.
[0036] In an embodiment of the present disclosure, there is provided a method for thermomechanical devulcanization of a rubber, wherein the vulcanized rubber is selected natural rubber, styrene butadiene rubber or isobutene isoprene rubber. In another embodiment of the present disclosure, there is provided a method for

thermomechanical devulcanization of a rubber, wherein the vulcanized rubber is
selected from natural rubber or styrene butadiene rubber.
[0037] In an embodiment of the present disclosure, there is provided a method for
thermomechanical devulcanization of a rubber, the method comprising: a) obtaining a
vulcanized rubber; b) grinding the vulcanized rubber into rubber granules; and c)
processing the rubber granules in a co-rotating twin screw extruder to obtain a
devulcanized rubber, wherein processing the rubber granules in a co-rotating twin
screw extruder is carried out at a screw speed of 400-1000 rpm and wherein the
vulcanized rubber is selected from the group consisting of natural rubber, styrene
butadiene rubber, butadiene rubber, isobutene isoprene rubber and combinations
thereof.
[0038] In an embodiment of the present disclosure, there is provided a method for
thermomechanical devulcanization of a rubber, wherein grinding the vulcanized rubber
into rubber granules of diameter in the range of 3 to 12 mm.
[0039] In an embodiment of the present disclosure, there is provided a method for
thermomechanical devulcanization of a rubber, wherein grinding the vulcanized rubber
into rubber granules of diameter in the range of 4 to 11 mm. In another embodiment of
the present disclosure, there is provided a method for thermomechanical
devulcanization of a rubber, wherein grinding the vulcanized rubber into rubber
granules of diameter in the range of 5 to 10 mm.
[0040] In an embodiment of the present disclosure, there is provided a method for
thermomechanical devulcanization of a rubber, the method comprising: a) obtaining a
vulcanized rubber; b) grinding the vulcanized rubber into rubber granules; and c)
processing the rubber granules in a co-rotating twin screw extruder to obtain a
devulcanized rubber, wherein grinding the vulcanized rubber into rubber granules of
diameter in the range of 3 to 12 mm.
[0041] In an embodiment of the present disclosure, there is provided a method for
thermomechanical devulcanization of a rubber, the method comprising: a) obtaining a

vulcanized rubber selected from the group consisting of natural rubber, styrene butadiene rubber, butadiene rubber, isobutene isoprene rubber and combinations thereof; b) grinding the vulcanized rubber into rubber granules of diameter in the range of 3 to 12 mm; and c) processing the rubber granules in a co-rotating twin screw extruder to obtain a devulcanized rubber, wherein processing the rubber granules in a co-rotating twin screw extruder is carried out at a screw speed of 400-1000 rpm. [0042] In an embodiment of the present disclosure, there is provided a method for thermomechanical devulcanization of a rubber, wherein processing the rubber granules in a co-rotating twin screw extruder is carried out at a temperature in the range of 50-250ºC.
[0043] In an embodiment of the present disclosure, there is provided a method for thermomechanical devulcanization of a rubber, wherein processing the rubber granules in a co-rotating twin screw extruder is carried out at a temperature in the range of 70-230ºC. In another embodiment of the present disclosure, there is provided a method for thermomechanical devulcanization of a rubber, wherein processing the rubber granules in a co-rotating twin screw extruder is carried out at a temperature in the range of 90-210ºC. In yet another embodiment of the present disclosure, there is provided a method for thermomechanical devulcanization of a rubber, wherein processing the rubber granules in a co-rotating twin screw extruder is carried out at a temperature of 200ºC. In one another embodiment of the present disclosure, there is provided a method for thermomechanical devulcanization of a rubber, wherein processing the rubber granules in a co-rotating twin screw extruder is carried out at a temperature of 150ºC. [0044] In an embodiment of the present disclosure, there is provided a method for thermomechanical devulcanization of a rubber, the method comprising: a) obtaining a vulcanized rubber; b) grinding the vulcanized rubber into rubber granules; and c) processing the rubber granules in a co-rotating twin screw extruder to obtain a devulcanized rubber, wherein processing the rubber granules in a co-rotating twin

screw extruder is carried out at a screw speed of 400-1000 rpm and at a temperature in the range of 50-250ºC.
[0045] In an embodiment of the present disclosure, there is provided a method for thermomechanical devulcanization of a rubber, the method comprising: a) obtaining a vulcanized rubber selected from the group consisting of natural rubber, styrene butadiene rubber, butadiene rubber, isobutene isoprene rubber and combinations thereof; b) grinding the vulcanized rubber into rubber granules of diameter in the range of 3 to 12 mm; and c) processing the rubber granules in a co-rotating twin screw extruder to obtain a devulcanized rubber, wherein processing the rubber granules in a co-rotating twin screw extruder is carried out at a screw speed of 400-1000 rpm and at a temperature in the range of 50-250ºC.
[0046] In an embodiment of the present disclosure, there is provided a method for thermomechanical devulcanization of a rubber, wherein grinding the vulcanized rubber into rubber granules is carried out in a mechanical grinder.
[0047] In an embodiment of the present disclosure, there is provided a method for thermomechanical devulcanization of a rubber, the method comprising: a) obtaining a vulcanized rubber; b) grinding the vulcanized rubber into rubber granules; and c) processing the rubber granules in a co-rotating twin screw extruder to obtain a devulcanized rubber, wherein processing the rubber granules in a co-rotating twin screw extruder is carried out at a screw speed of 400-1000 rpm and wherein grinding the vulcanized rubber into rubber granules is carried out in a mechanical grinder. [0048] In an embodiment of the present disclosure, there is provided a method for thermomechanical devulcanization of a rubber, the method comprising: a) obtaining a vulcanized rubber selected from the group consisting of natural rubber, styrene butadiene rubber, butadiene rubber, isobutene isoprene rubber and combinations thereof; b) grinding the vulcanized rubber in a mechanical grinder into rubber granules of diameter in the range of 3 to 12 mm; and c) processing the rubber granules in a co-rotating twin screw extruder to obtain a devulcanized rubber, wherein processing the

rubber granules in a co-rotating twin screw extruder is carried out at a screw speed of 400-1000 rpm and at a temperature in the range of 50-250ºC.
[0049] In an embodiment of the present disclosure, there is provided a method for thermomechanical devulcanization of a rubber as disclosed herein, wherein processing the rubber granules in a co-rotating twin screw extruder is carried out with feed rate of 2-10 kg/hour, thereby maintaining the kneading block at 10-90%.
[0050] In an embodiment of the present disclosure, there is provided a method for thermomechanical devulcanization of a rubber as disclosed herein, wherein processing the rubber granules in a co-rotating twin screw extruder is carried out with feed rate of 3-8 kg/hour, thereby maintaining the kneading block at 15-80%. In another embodiment of the present disclosure, there is provided a method for thermomechanical devulcanization of a rubber as disclosed herein, wherein processing the rubber granules in a co-rotating twin screw extruder is carried out with feed rate of 5 kg/hour, thereby maintaining the kneading block at 24%.
[0051] In an embodiment of the present disclosure, there is provided a method for thermomechanical devulcanization of a rubber, the method comprising: a) obtaining a vulcanized rubber; b) grinding the vulcanized rubber into rubber granules; and c) processing the rubber granules in a co-rotating twin screw extruder to obtain a devulcanized rubber, wherein processing the rubber granules in a co-rotating twin screw extruder is carried out at a screw speed of 400-1000 rpm and wherein processing the rubber granules in a co-rotating twin screw extruder is carried out with feed rate of 2-10 kg/hour, thereby maintaining the kneading block at 10-90%.
[0052] In an embodiment of the present disclosure, there is provided a method for thermomechanical devulcanization of a rubber, the method comprising: a) obtaining a vulcanized rubber selected from the group consisting of natural rubber, styrene butadiene rubber, butadiene rubber, isobutene isoprene rubber and combinations thereof; b) grinding the vulcanized rubber in a mechanical grinder into rubber granules of diameter in the range of 3 to 12 mm; and c) processing the rubber granules in a co-

rotating twin screw extruder with feed rate of 2-10 kg/hour, thereby maintaining the kneading block at 10-90% to obtain a devulcanized rubber, wherein processing the rubber granules in a co-rotating twin screw extruder is carried out at a screw speed of 400-1000 rpm and at a temperature in the range of 50-250ºC.
[0053] In an embodiment of the present disclosure, there is provided a method for thermomechanical devulcanization of a rubber as disclosed herein, wherein the devulcanized rubber has Mooney viscosity in the range of 30 to 70 at 100ºC. [0054] In an embodiment of the present disclosure, there is provided a method for thermomechanical devulcanization of a rubber as disclosed herein, wherein the devulcanized rubber has Mooney viscosity in the range of 35 to 65 at 100ºC. In another embodiment of the present disclosure, there is provided a method for thermomechanical devulcanization of a rubber as disclosed herein, wherein the devulcanized rubber has Mooney viscosity in the range of 36 to 50 at 100ºC. In yet another embodiment of the present disclosure, there is provided a method for thermomechanical devulcanization of a rubber as disclosed herein, wherein the devulcanized rubber has Mooney viscosity of 36.5 at 100ºC. In one another embodiment of the present disclosure, there is provided a method for thermomechanical devulcanization of a rubber as disclosed herein, wherein the devulcanized rubber has Mooney viscosity of 40.7 at 100ºC
[0055] In an embodiment of the present disclosure, there is provided a method for thermomechanical devulcanization of a rubber, the method comprising: a) obtaining a vulcanized rubber; b) grinding the vulcanized rubber into rubber granules; and c) processing the rubber granules in a co-rotating twin screw extruder to obtain a devulcanized rubber, wherein processing the rubber granules in a co-rotating twin screw extruder is carried out at a screw speed of 400-1000 rpm and wherein the devulcanized rubber has Mooney viscosity in the range of 30 to 70 at 100ºC. [0056] In an embodiment of the present disclosure, there is provided a method for thermomechanical devulcanization of a rubber, the method comprising: a) obtaining a

vulcanized rubber selected from the group consisting of natural rubber, styrene butadiene rubber, butadiene rubber, isobutene isoprene rubber and combinations thereof; b) grinding the vulcanized rubber in a mechanical grinder into rubber granules of diameter in the range of 3 to 12 mm; and c) processing the rubber granules in a co-rotating twin screw extruder with feed rate of 2-10 kg/hour, thereby maintaining the kneading block at 10-90% to obtain a devulcanized rubber, wherein processing the rubber granules in a co-rotating twin screw extruder is carried out at a screw speed of 400-1000 rpm and at a temperature in the range of 50-250ºC and wherein the devulcanized rubber has Mooney viscosity in the range of 30 to 70 at 100ºC. [0057] In an embodiment of the present disclosure, there is provided a method for thermomechanical devulcanization of a rubber, wherein the devulcanized rubber is in the form of strand, granule, sheet, or lump.
[0058] In an embodiment of the present disclosure, there is provided a method for thermomechanical devulcanization of a rubber, the method comprising: a) obtaining a vulcanized rubber selected from the group consisting of natural rubber, styrene butadiene rubber, butadiene rubber, isobutene isoprene rubber and combinations thereof; b) grinding the vulcanized rubber in a mechanical grinder into rubber granules of diameter in the range of 3 to 12 mm; and c) processing the rubber granules in a co-rotating twin screw extruder with feed rate of 2-10 kg/hour, thereby maintaining the kneading block at 10-90% to obtain a devulcanized rubber, wherein processing the rubber granules in a co-rotating twin screw extruder is carried out at a screw speed of 400-1000 rpm and at a temperature in the range of 50-250ºC and wherein the devulcanized rubber has Mooney viscosity in the range of 30 to 70 at 100ºC and wherein the devulcanized rubber is in the form of strand, granule, sheet, or lump. [0059] In an embodiment of the present disclosure, there is provided a devulcanized rubber obtained by the method, the method comprising: a) obtaining a vulcanized rubber; b) grinding the vulcanized rubber into rubber granules; and c) processing the rubber granules in a co-rotating twin screw extruder to obtain a devulcanized rubber,

wherein processing the rubber granules in a co-rotating twin screw extruder is carried out at a screw speed of 400-1000 rpm.
[0060] In an embodiment of the present disclosure, there is provided a devulcanized rubber obtained by the method as disclosed herein, wherein the devulcanized rubber has Mooney viscosity in the range of 30 to 70 at 100ºC and wherein the devulcanized rubber is in the form of strand, granule, sheet, or lump.
[0061] In an embodiment of the present disclosure, there is provided a reclaim rubber obtained by the method, the method comprising: a) obtaining a vulcanized rubber; b) grinding the vulcanized rubber into rubber granules; and c) processing the rubber granules in a co-rotating twin screw extruder to obtain a devulcanized rubber, wherein processing the rubber granules in a co-rotating twin screw extruder is carried out at a screw speed of 400-1000 rpm.
[0062] In an embodiment of the present disclosure, there is provided an article comprising the devulcanized rubber obtained by the method, the method comprising: a) obtaining a vulcanized rubber; b) grinding the vulcanized rubber into rubber granules; and c) processing the rubber granules in a co-rotating twin screw extruder to obtain a devulcanized rubber, wherein processing the rubber granules in a co-rotating twin screw extruder is carried out at a screw speed of 400-1000 rpm.
[0063] 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
[0064] 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.
[0065] The forthcoming examples explains that how the present disclosure provides a method for devulcanization of the vulcanized rubber using co-rotating twin screw extruder. Thermomechanical devulcanization method of the present disclosure provides a convenient, cost effective and a simple method for devulcanization. The present disclosure reveals a method, in which the vulcanized rubber is obtained and ground in to rubber granules. Then these rubber granules are processed under specific condition to obtain the devulcanized rubber. The devulcanized rubber with desired properties were achieved. The devulcanized rubber of the present disclosure has lowered Mooney viscosity so that it can be flows easily and can be molded to different shapes. In this way, this method helps in recycling and reforming of used and vulcanized rubber into various articles.
EXAMPLE 1
MATERIALS REQUIRED
[0066] For the purpose of the present disclosure, devulcanization was carried out in a
co-rotating twin screw extruder CRTSE (Alpha 25, STEER Eng., India) using screw
and machine design as shown in Figure 1. The Mooney viscosity of devulcanized

rubber samples were measured using an Alpha Technologies MV2000 Mooney viscometer according to ASTM D1646-04 method.
Thermomechanical devulcanization of rubber of the present disclosure [0067] Scrapped tire and tire curing bladder were taken separately and was ground in a conventional grinder to obtain granules of the vulcanized rubber granules of scrapped tire and tire curing bladder respectively. The vulcanized rubber granules of scrapped tire contain vulcanized rubber mixture of natural rubber, styrene butadiene rubber and butadiene rubber, whereas vulcanized rubber granules of tire curing bladder contain vulcanized isobutene isoprene rubber. These granules of vulcanized rubber were of size ranging between 3 to 12 mm and more specifically in the range of 5 to 10mm. [0068] Vulcanized isobutene isoprene rubber granules of tire curing bladder were fed in a co-rotating twin screw extruder (CRTSE) and processed at a specific screw speed, barrel temperature and kneading elements as mentioned in Table 1 and devulcanization of the vulcanized rubber was completed. The devulcanized rubber obtained in strand or granule or sheet or lump form based on the die head used. Table 1

Devulcanization parameter Sample-1 Sample-2 Sample-3 Sample-4
Screw Speed (RPM) 300 800 300 800
Barrel Temperature (oC) 200 200 150 150
Characterization
Mooney Viscosity of devulcanized rubber (ML 1+4) at 100oC 96.2 36.5 95.6 40.7
[0069] Sample 1 was devulcanized at a screw speed of 300 rpm and at a temperature of 200ºC. Similarly, samples 2, 3 and 4 were devulcanized at varying screw speed and at a varying temperature. The processing of the rubber granules in the co-rotating twin screw extruder was carried out with feed rate of 5 kg per hour with the kneading block

at 24%. With lower kneading block % devulcanization was incomplete and with higher kneading block % there might be degradation of the rubber, hence processing of the rubber granules in a co-rotating twin screw extruder was carried out with feed rate of 2-10 kg/hour, thereby maintaining the kneading block at 10-90%. The devulcanized rubber obtained, were subjected to Mooney viscosity measurements. It can be observed that Mooney viscosity of samples 1 and 3 were 96.2 and 95.6 respectively. And for samples 2 and 4 Mooney viscosity were 36.5 and 40.7 respectively. When Mooney viscosity is lower the flow is easier and is favorable for molding operations. Hence, it was demonstrated from the samples 2 and 4 that the devulcanization at temperatures of 200ºC and 150ºC respectively and under a screw speed of 800 rpm are the desired devulcanized rubber. And from the results it can be deduced that the screw speed played a major role to achieve the objectives of the instant invention. Further, Mooney viscosity measurements were done at different places of the same sample and it was found that all the Mooney viscosity values were same. This proved that devulcanized rubber obtained from the process of the present disclosure was homogenous and had a uniform distribution.
[0070] The examples explained above proved that devulcanized rubber of lowered Mooney viscosity was achieved only by the process disclosed in the present disclosure. Any deviation in the process parameters such as screw speed, temperature resulted in the devulcanized rubber of undesired properties. Hence, the present disclosure provides a method for producing devulcanized rubber which is capable of flowing easily and which can be molded in to articles of desired shapes. And thus, the process of present disclosure enables recycling and reuse of vulcanized rubber reformed to various usable articles.
Advantages of the present disclosure
[0071] The present disclosure discloses a thermomechanical devulcanization method
comprising processing the rubber granules in co-rotating twin screw extruder at screw

speed in the range of 400 to 1000 rpm. The devulcanization method of the present disclosure results in devulcanized rubber with lowered Mooney viscosity in the range of 30 to 70. The devulcanized rubber with desired properties is obtained by varying the screw design, screw speed and temperature. In the devulcanization method of the present disclosure no chemicals additives are used. This method can devulcanize any vulcanized rubber. The method provided herein is cost effective and is environmentally friendly. The devulcanization method of the present disclosure can be used for recycling of scrapped rubber products and reuse in products including tires, hose, conveyor belt, boat, dock fenders, mats, hot water bags, O rings, rail pads, rubber rollers and similar vulcanizable elastomeric products.

I/We Claim:
1. A method for thermomechanical devulcanization of a rubber, the method
comprising:
a) obtaining a vulcanized rubber;
b) grinding the vulcanized rubber into rubber granules; and
c) processing the rubber granules in a co-rotating twin screw extruder to obtain a devulcanized rubber,
wherein processing the rubber granules in a co-rotating twin screw extruder is carried out at a screw speed of 400-1000 rpm.
2. The method as claimed in claim 1, wherein the vulcanized rubber is selected from the group consisting of natural rubber, styrene butadiene rubber, butadiene rubber, isobutene isoprene rubber, and combinations thereof.
3. The method as claimed in claim 1, wherein grinding the vulcanized rubber into rubber granules of diameter in the range of 3 to 12 mm.
4. The method as claimed in claim 1, wherein processing the rubber granules in a co-rotating twin screw extruder is carried out at a temperature in the range of 50-250ºC.
5. The method as claimed in claim 1, wherein grinding the vulcanized rubber into rubber granules is carried out in a mechanical grinder.
6. The method as claimed in claim 1, wherein processing the rubber granules in a co-rotating twin screw extruder is carried out with feed rate of 2-10 kg/hour, thereby maintaining the kneading block at 10-90%.
7. The method as claimed in claim 1, wherein the devulcanized rubber has Mooney viscosity in the range of 30 to 70 at 100ºC.
8. The method as claimed in claim 1, wherein the devulcanized rubber is in the form of strand, granule, sheet, or lump.

9. A devulcanized rubber obtained by the method as claimed in any one of the claims
1 to 8.
10. A reclaim rubber obtained by the method as claimed in any one of the claims 1 to
8.
11. An article comprising the devulcanized rubber as claimed in claim 9.