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: PREPARATION OF GRAPHENE-RUBBER MASTERBATCH
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 present disclosure broadly relates to rubber compounds, in particular relates to method of preparing graphene-rubber masterbatch and a tyre composition comprising the graphene-rubber masterbatch thereof. 5
BACKGROUND OF INVENTION
[0002] Rubbers are widely used in various industrial applications due to their captivating characteristics like flexibility, durability, and reliability. These elastomer composites are utilized for preparing an extensive variety of products, including
10 conveyor belts, tyres for automobiles, sidewalls, wire skim, wires, cables, and the
like. The rubber compounds are extensively studied, and it has been well established that rubbers/elastomers require incorporation of reinforcement fillers to enhance various properties for different applications. The reinforcing fillers enhance the mechanical and dynamic properties of rubber and common reinforcing fillers include
15 silica, carbon black, clays, calcium carbonate and so on. However, to further aid the
improvement in properties, several additives are added to form elastomeric masterbatches. The incorporation of reinforcement fillers such as graphene had sparked interest which, not surprisingly, is growing exponentially because of its outstanding properties and immense application possibilities.
20 [0003] Graphene with its unparalleled qualities, particularly its exceptional
conductivity, outstanding strength, and elasticity, makes it an extremely promising material. Due to its ability to impart properties such as less heat build-up, fuel consumption, weight reduction, air permeability, and enhancements in mechanical strength, thermal and electrical conductivity, hardness, wet grip, impact strength, and
25 lateral stiffness, graphene, a two-dimensional allotrope of carbon, can be used as a
reinforcing filler in various tire parts.
[0004] However, the existing methods for preparing graphene involve expensive equipments, complex process steps, difficulties in bulk production, separation, purification, and drying processes. Additionally, incorporating graphene in tyre
30 compounds is challenging and economically not feasible. Another challenge which
arises is the inadequate dispersion of graphene during processing. Good dispersion

of reinforcement fillers is essential for achieving good quality and consistent product
performance. Dry graphene being fluffy, is difficult to disperse within a rubber
matrix. However, creating a graphene-rubber masterbatch (MB) makes dispersion
within the rubber matrix much simpler.
5 [0005] Therefore, there is an arising need for the development of a cost effective and
simple method for preparing a graphene-rubber masterbatch with effective dispersion of graphene in the rubber matrix for tyre compounding.
SUMMARY OF THE INVENTION
[0006] In first aspect of the present disclosure, there is provided a method of
10 preparing a graphene-rubber masterbatch, the method comprising: (a) mixing
graphite and at least one rubber in a two-roll mill to obtain a mixture; and (b) passing the mixture through the two-roll mill to obtain the graphene-rubber masterbatch, wherein the two-roll mill is maintained in a friction ratio in a range of 1:2 to 1:6. [0007] In second aspect of the present disclosure, there is provided a tyre
15 composition comprising: (a) 2 to 15 phr of the graphene-rubber masterbatch obtained
by the method as disclosed herein; (b) 85 to 98 phr of a rubber; (c) 30 to 50 phr of a carbon black; (d) 0.01 to 15 phr of a first additive; and (e) 1 to 5 phr of a second additive. [0008] In third aspect of the present disclosure, there is provided a process for
20 preparing the tyre composition as disclosed herein, the process comprising: mixing
the graphene-rubber masterbatch with a rubber, a carbon black, a first additive and a second additive to obtain a second mixture; and curing the second mixture to obtain the composition. [0009] In fourth aspect of the present disclosure, there is provided an article
25 comprising the graphene-rubber masterbatch obtained by the method as disclosed
herein or the composition as disclosed herein.
[0010] In fifth aspect of the present disclosure, there is provided use of the graphene-rubber masterbatch obtained by the method as disclosed herein or the composition as disclosed herein.
30 [0011] 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. 5
BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS
[0012] The following figures form a part of the present specification and are included to further illustrate aspects of the present disclosure. The disclosure may be better understood by reference to the figures in combination with the detailed
10 description of the specific embodiments presented herein.
[0013] Figure 1 depicts the variation of Mooney viscosity of graphene-rubber masterbatch (GRMB) prepared by varying number of passes through two-roll mill, in accordance with an embodiment of the present disclosure. [0014] Figure 2 depicts atomic force microscopy (AFM) images of (a) graphite; and
15 (b) graphene in the graphene-rubber masterbatch (GRMB-4), in accordance with an
implementation of the present disclosure.
[0015] Figure 2(c) depicts graphene in graphene-rubber masterbatch obtained using co-rotating twin screw extruder.
20 DETAILED DESCRIPTION OF THE INVENTION
[0016] 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
25 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
[0017] For convenience, before further description of the present disclosure, certain terms employed in the specification, and examples are delineated here. These
30 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.
[0018] 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.
5 [0019] 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”.
[0020] Throughout this specification, unless the context requires otherwise the word
“comprise”, and variations such as “comprises” and “comprising”, will be
10 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.
[0021] The term “including” is used to mean “including but not limited to”.
“Including” and “including but not limited to” are used interchangeably.
[0022] The term “phr” used herein refers to parts per hundred rubber/resin. It is a
15 unit well defined in the field of rubber technology to define the amount of ingredients
used. The unit “phr” can also be interchangeably used with the unit “gram” as both
denote phr/gram of ingredient per 100 phr/gram of rubber.
[0023] The term “rpm” used herein refers to rotations/revolutions per minute. It is a
unit well used in the field of rubber technology to define the speed of any rotating
20 part of the machine, in this disclosure especially for twin-roll mill.
[0024] The term “at least one rubber” used herein refers to a rubber in the form of
latex or dispersion or solution. Examples include, but are not limited to, natural
rubber latex, RSS3, RSS4 and the like.
[0025] The term “rubber” used herein refers to natural rubber, synthetic rubber such
25 as butadiene rubber, styrene butadiene rubber, or combinations thereof.
[0026] The term “activator” used herein refers to the substances that have a strong
activation effect of increasing the vulcanization speed in the cross-linking reaction
of rubbers. Activators are required to achieve the desired vulcanization and end-user
properties. In the present disclosure activator includes but is not limited to zinc oxide,
30 stearic acid, magnesium oxide, or combinations thereof.

[0027] The term “accelerator” used herein refers to the substances used with a cross-
linking agent to increase the speed of vulcanization of rubber and enhance its
physical properties. In the present disclosure accelerator includes but is not limited
to N-cyclohexylbenzothiazole-2-sulphenamide (CBS), 2-mercaptobenzothiazole
5 (MBT), bis(2-benzothiazole) disulfide (MBTS), diphenyl guanidine (DPG),
diorthotolyl guanidine (DOTG), tetramethyl thiuram monosulfide (TMTM), tetramethyl thiuram disulfide (TMTD), diethyl dithiocarbamate (ZDEC), dibutyl-dithiocarbamate (ZDBC), or combinations thereof. [0028] The term “antioxidant” used herein refers to the substances that are used to
10 protect rubber articles against the attack of oxygen. In the present disclosure
antioxidants include but are not limited to N-1,3-dimethylbutyl-N'-phenyl-p-phenylenediamine (6PPD), microcrystalline (MC) wax, 2,2,4-trimethyl-1,2-dihydroquinoline (TMQ), or combinations thereof. [0029] The term “peptizer” used herein refers to the substances which break down
15 polymer chains and reduce rubber viscosity during its processing. In the present
disclosure peptizer includes but not limited to 2,2'-dithiobisbenzanilide (DBD), pentachlorothiophenol (PCTP), or combinations thereof.
[0030] The term “processing aid” used herein refers to the substances which helps in rubber processing. Examples include, but are not limited to, wood rosin,
20 processing oil, or combinations thereof.
[0031] The term “retarder” used herein refers to the substances added to rubber compounds to delay premature vulcanization during its processing. Examples include, but not limited to, N- (cyclohexylthio) phthalimide (CTP), benzoic acid, salicylic acid, phthalic anhydride, or combinations thereof.
25 [0032] The term “crosslinking agent” used herein refers to the substances that are
used to form chemical links between molecular chains to form a three-dimensional network of connected molecules. Vulcanization/hardening of rubber using sulphur is an example for crosslinking. In the present disclosure the crosslinking agent includes but not limited to sulphur, peroxide, metal oxide, and resin.
30 [0033] The term “nip gap” used herein refers to the distance between the two rolls
in a two-roll mill. It is usually measured in millimeters (mm) or micrometers (µm).

[0034] The term “friction ratio” used herein refers to the ratio of speed of the two
rolls in the two-roll mill. It is calculated by dividing the surface speed of the fast roll
by the surface speed of the slow roll. The friction ratio in the present disclosure is in
a range of 1:2 to 1:6.
5 [0035] The term “modulus at100%” used herein refers to the force required for 100%
elongation of a material. Similarly, the terms, “modulus at 50%”, “modulus at 200%” “modulus at 300%”, and “modulus at 400%” refers to the force required for 50%, 200%, 300% and 400% elongation respectively. It is measured in units of pressure as MPa or kg/cm2.
10 [0036] The term “tensile strength” used herein refers to the maximum load a material
can withstand before fracture, breaking, tearing, etc. In the present disclosure tensile strength of the tyre composition comprising the graphene-rubber masterbatch of the present disclosure is in a range of 295 to 315 kg/cm2. [0037] The term “elongation at break %” used herein refers to the percentage change
15 in elongation of a material at the instant of break. In the present disclosure elongation
at break of the tyre composition comprising the graphene-rubber masterbatch of the present disclosure is in a range of 500 to 580%.
[0038] The terms “graphene-rubber masterbatch” or “GRMB” refers to a
composition comprising graphene and the rubber, wherein the rubber is dispersed
20 between the exfoliated layers of graphene. When graphite and rubber is mixed and
passed through the two-roll mill, the shear stress causes graphenic layers of graphite to open up, rubber chain may break into smaller lengths and enter between graphenic layer resulting exfoliation of graphitic layer and formation of few-layer graphene (FLG). There is a less chance of FLG to restack as inserted rubber chain will prevent
25 from it. Thus, the graphene-rubber masterbatch has graphene uniformly dispersed in
the rubber matrix. The graphene- rubber masterbatch in the present disclosure comprises rubber to graphite weight ratio in the range of 80:20 to 95:5. [0039] The term “graphite” refers to the crystalline allotropic form of carbon consisting of stacked layers of graphene. In the present disclosure, graphite can be
30 virgin graphite or oxidized graphite.

[0040] The term “graphene” refers to an allotrope of carbon arranged in a hexagonal
lattice. In the present disclosure, the graphene-rubber masterbatch comprises
graphene in a weight range of 10 to 20% (w/w), with respect to total weight of the
graphene-rubber masterbatch.
5 [0041] The term “number of passes” refers to the number of times a mixture
comprising graphite and rubber was allowed to pass through the two-roll mill to obtain the graphene-rubber masterbatch. The number of passes in the present disclosure is 1 to 25 times. The number of passes plays a significant role in obtaining the masterbatch for a tyre composition with desired properties.
10 [0042] The term “ML (1+4) @ 100°C” (or Mooney Viscosity at 100°C) used herein
refers to conditions maintained while performing viscosity analysis on a sample of GRMB and is a measure of internal friction and elasticity of the compounds/composition or mixture. It indicates the effect of temperature and time on the viscosity of rubber compounds. It is measured in terms of torque, required to
15 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 5 twice of that measured with a small rotor. Viscosity is measured in Mooney Units (MU)
20 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 100°C refers to the test temperature.
[0043] 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
25 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, friction ratio ranges from 1:2.5 to 1:5.3 should be interpreted to include not only the explicitly
30 recited limits of about 1:2.5 to about 1:5.3, but also to include sub-ranges, such as
1:3, 1:3.5, 1:4, 1:4.5, and so forth.

[0044] As discussed in the background, cost for producing graphene commercially
using existing technologies is very high due to requirement of expensive equipment,
time-consuming process, high potential for contamination necessitating a
purification step, variability in quality and properties of graphene formed depending
5 on process steps, parameters and reagents used, and the need for specialized
equipment and expertise. For the reasons stated, incorporating graphene in tyre compounds is not cost effective. Another major challenge regarding the preparation of graphene- rubber masterbatch (GRMB) is the inadequate dispersion of graphene in rubber matrix during processing. Even though graphene-rubber masterbatch could
10 be prepared using co-rotating twin screw extruder, it has drawbacks such as limited
loading of graphene and higher loading of graphene resulting in deteriorating properties. Strong kneading in the co rotating-twin screw extruder lead to the breaking of the graphene sheets in the masterbatch and causes decrease in mechanical strength of the compositions thereof.
15 [0045] Accordingly, the present disclosure relates to a simple, quick, low-cost
method of manufacturing graphene-rubber masterbatch (GRMB) by mixing virgin graphite with rubber. In order to avoid the aforementioned problems associated with preparation of graphene, the present disclosure utilizes a two-roll mill to manufacture graphene from graphite and ensure complete dispersion of graphene in rubber and
20 thereby providing enhanced tensile and mechanical properties to the tyre compound.
[0046] When the mixture of rubber and graphite is passed through the two-roll mill, the graphenic layers of graphite open due to shear stress and rubber chain break into smaller lengths, enter between graphenic layer causing exfoliation of graphitic layer. This results in the formation of few-layer graphene (FLG). There is less chance for
25 the FLG to restack as inserted rubber chain will prevent from it.
[0047] The method of the present disclosure of obtaining graphene from graphite is very simple, and no chemical, solvent, purification and drying step is involved. Hence, manufacturing cost of graphene is very less and therefore the graphene-rubber masterbatch is economically feasible to use in tyre compound. The method of
30 preparing graphene-rubber masterbatch using two-roll mill is also environmentally
friendly. Thus, the present disclosure provides a process highly effective in

producing graphene from graphite by applying shear stress and preparing graphene-
rubber masterbatch using two-roll mill, which removes the problems emerged due to
other methods. Hence, for the aforementioned reasons, the method of preparing
graphene-rubber masterbatch as disclosed in the present disclosure, is a simple, cost-
5 effective, economical, and a time-efficient process.
[0048] 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
10 disclosure, the preferred methods and materials are now described.
[0049] 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.
15 [0050] In an embodiment of the present disclosure, there is provided a method of
preparing a graphene-rubber masterbatch, the method comprising: (a) mixing graphite and at least one rubber in a two-roll mill to obtain a mixture; and (b) passing the mixture through the two-roll mill, wherein the friction ratio is in a range of 1:2 to 1:6.
20 [0051] In an embodiment of the present disclosure, there is provided a method of
preparing a graphene-rubber masterbatch, as disclosed herein, wherein the two-roll mill is maintained in a friction ratio in a range of 1:2.2 to 1:5.8. In another embodiment of the present disclosure, the two-roll mill is maintained in a friction ratio in a range of 1:2.4 to 1:5.6. In yet another embodiment of the present disclosure,
25 the two-roll mill is maintained in a friction ratio in a range of 1:2.5 to 1:5.3. In one
another embodiment of the present disclosure, the two-roll mill is maintained in a friction ratio of 1:3.5.
[0052] In an embodiment of the present disclosure, there is provided a method of preparing a graphene-rubber masterbatch as disclosed herein, wherein passing the
30 mixture through the two-roll mill is carried out at least twice. In another embodiment
of the present disclosure, wherein passing the mixture through the two-roll mill is

carried out two to twenty times. In yet another embodiment of the present disclosure, passing the mixture through the two-roll mill is carried out twenty times. [0053] In an embodiment of the present disclosure, there is provided a method of preparing a graphene-rubber masterbatch as disclosed herein, wherein the graphene-5 rubber masterbatch has Mooney viscosity in a range of 20 to 25 MU (ML1+4@100℃). In another embodiment of the present disclosure, the graphene-rubber masterbatch has Mooney viscosity in a range of 22 to 25 MU (ML1+4@100℃). [0054] an embodiment of the present disclosure, there is provided a method of
10 preparing a graphene-rubber masterbatch as disclosed herein, wherein the rubber and graphite are taken in a weight ratio range of 80:20 to 95:5. In another embodiment of the present disclosure, the rubber and graphite are taken in a weight ratio range of 83:17 to 90:10. In yet another embodiment of the present disclosure, the rubber and graphite are taken in a weight ratio of 85:15.
15 [0055] In an embodiment of the present disclosure, there is provided a method of preparing a graphene-rubber masterbatch as disclosed herein, wherein the rubber is selected from natural rubber, butadiene rubber, styrene butadiene rubber, or combinations thereof; and the graphite is virgin graphite or oxidized graphite. In another embodiment of the present disclosure, the rubber is natural rubber; and the
20 graphite is virgin graphite.
[0056] In an embodiment of the present disclosure, there is provided a method of preparing a graphene-rubber masterbatch as disclosed herein, wherein the graphene-rubber masterbatch comprises graphene in a weight range of 10 to 20% (w/w) with respect to total weight of the graphene-rubber masterbatch. In another embodiment
25 of the present disclosure, the graphene-rubber masterbatch comprises graphene in a weight range of 12 to 18% (w/w) with respect to total weight of the graphene-rubber masterbatch. In yet another embodiment of the present disclosure, the graphene-rubber masterbatch comprises graphene in a weight range of 13 to 15% (w/w) with respect to total weight of the graphene-rubber masterbatch. In more embodiment of
30 the present disclosure, about 6.67 phr of the graphene-rubber masterbatch comprises 1 phr of graphene.

[0057] In an embodiment of the present disclosure, there is provided a method of preparing a graphene-rubber masterbatch, the method comprising: mixing graphite and at least one rubber taken in a weight ratio range of 80:20 to 95:5 in a two-roll mill to obtain a mixture; (b) passing the mixture through the two-roll mill at least 5 once upto twenty times to obtain the graphene-rubber masterbatch, wherein the two-roll mill is maintained in a friction ratio in a range of 1:2 to 1:6; and the graphene-rubber masterbatch has Mooney viscosity in a range of 20 to 25 MU (ML1+4@100℃). [0058] In an embodiment of the present disclosure, there is provided a method of
10 preparing a graphene-rubber masterbatch, the method comprising: mixing graphite and at least one rubber taken in a weight ratio range of 80:20 to 95:5 in a two-roll mill to obtain a mixture; (b) passing the mixture through the two-roll mill at least once and up to twenty times to obtain the graphene-rubber masterbatch, wherein the two-roll mill is maintained in a friction ratio in a range of 1:2 to 1:6; the graphene-
15 rubber masterbatch comprises graphene in a weight range of 10 to 20% (w/w) with respect to total weight of the graphene-rubber masterbatch; and the graphene-rubber masterbatch has Mooney viscosity in a range of 20 to 25 MU (ML1+4@100℃). [0059] In an embodiment of the present disclosure, there is provided a tyre composition comprising: (a) 2 to 15 phr of the graphene-rubber masterbatch obtained
20 by the method as disclosed herein; (b) 85 to 98 phr of a rubber; (c) 30 to 50 phr of a carbon black; (d) 0.01 to 15 phr of a first additive; and (e) 1 to 5 phr of a second additive. In another embodiment of the present disclosure, there is provided a tyre composition comprising: (a) 5 to 10 phr of the graphene-rubber masterbatch obtained by the method as disclosed herein; (b) 90 to 96 phr of a rubber; (c) 35 to 45 phr of a
25 carbon black; (d) 5 to 15 phr of a first additive; and (e) 2 to 4 phr of a second additive. [0060] In an embodiment of the present disclosure, there is provided a tyre composition as disclosed herein, wherein the graphene-rubber masterbatch comprises graphene in a weight range of 0.3 to 5 phr, with respect to total weight of the graphene-rubber masterbatch. In another embodiment of the present disclosure,
30 the graphene-rubber masterbatch comprises graphene in a weight range of 0.4 to 4 phr, with respect to total weight of the graphene-rubber masterbatch. In yet another

embodiment of the present disclosure, the graphene-rubber masterbatch comprises graphene in a weight range of 0.5 to 2 phr, with respect to total weight of the graphene-rubber masterbatch.
[0061] In an embodiment of the present disclosure, there is provided a tyre
5 composition as disclosed herein, wherein the rubber is selected from natural rubber,
butadiene rubber, styrene butadiene rubber, or combinations thereof; the carbon black is N134; the first additive is selected from a peptizer, an activator, an antioxidant, a processing aid, or combinations thereof; and the second additive is selected from a crosslinking agent, an accelerator, a retarder, or combinations
10 thereof.
[0062] In an embodiment of the present disclosure, there is provided a tyre composition as disclosed herein, the rubber is natural rubber; and the carbon black is N134. [0063] In an embodiment of the present disclosure, there is provided a tyre
15 compound, wherein the peptizer is selected from 2,2'-dithiobisbenzanilide (DBD),
pentachlorothiophenol (PCTP), or combinations thereof; the activator is selected from zinc oxide, stearic acid, magnesium oxide, or combinations thereof; the antioxidant is selected from N-1,3-dimethylbutyl-N'-phenyl-p-phenylenediamine (6PPD), microcrystalline (MC) wax, 2,2,4-trimethyl-1,2-dihydroquinoline (TMQ),
20 or combinations thereof; the processing aid is selected from wood rosin, processing
oil, or combinations thereof; the crosslinking agent is selected from sulphur, peroxide, metal oxide, resin, or combinations thereof; the accelerator is selected from N-cyclohexylbenzothiazole-2-sulphenamide (CBS), 2- mercaptobenzothiazole (MBT), bis(2-benzothiazole) disulfide (MBTS), diphenyl guanidine (DPG),
25 diorthotolyl guanidine (DOTG), tetramethyl thiuram monosulfide (TMTM),
tetramethyl thiuram disulfide (TMTD), diethyl dithiocarbamate (ZDEC), dibutyl-dithiocarbamate (ZDBC), or combinations thereof; and the retarder is selected from N- (cyclohexylthio) phthalimide (CTP), benzoic acid, salicylic acid, phthalic anhydride, or combinations thereof.
30 [0064] In an embodiment of the present disclosure, there is provided a tyre
compound, wherein the first additive is selected from 2,2'-dithiobisbenzanilide

(DBD), pentachlorothiophenol (PCTP), zinc oxide, stearic acid, magnesium oxide, from N-1,3-dimethylbutyl-N'-phenyl-p-phenylenediamine (6PPD), MC wax, 2,2,4-trimethyl-1,2-dihydroquinoline (TMQ), wood rosin, processing oil, and second additive is selected from sulphur, peroxide, metal oxide, resin, -5 cyclohexylbenzothiazole-2-sulphenamide (CBS), 2- mercaptobenzothiazole (MBT), bis(2-benzothiazole) disulfide (MBTS), diphenyl guanidine (DPG), diorthotolyl guanidine (DOTG), tetramethyl thiuram monosulfide (TMTM), tetramethyl thiuram disulfide (TMTD), diethyl dithiocarbamate (ZDEC), dibutyl-dithiocarbamate (ZDBC), N- (cyclohexylthio) phthalimide (CTP), benzoic acid, salicylic acid,
10 phthalic anhydride, or combinations thereof.
[0065] In an embodiment of the present disclosure, there is provided a tyre composition as disclosed herein, wherein the composition exhibits tensile strength in a range of 295 to 315 kg/cm2; elongation at break in a range of 500 to 580%; and modulus at 100% elongation in a range of 20 to 35 kg/cm2. In another embodiment
15 of the present disclosure, wherein the composition exhibits tensile strength in a range of 300 to 310 kg/cm2; elongation at break in a range of 510 to 565%; and modulus at 100% elongation in a range of 24 to 32 kg/cm2.
[0066] In an embodiment of the present disclosure, there is provided a graphene-rubber masterbatch obtained by a method comprising: (a) mixing graphite and at
20 least one rubber in a two-roll mill to obtain a mixture; and (b) passing the mixture through the two-roll mill, where the friction ratio is in a range of 1:2 to 1:6. [0067] In an embodiment of the present disclosure, there is provided a process for preparing the composition as disclosed herein, the process comprising: mixing the graphene-rubber masterbatch with a rubber, a carbon black, a first additive and a
25 second additive to obtain a second mixture; and curing the second mixture to obtain the composition.
[0068] In an embodiment of the present disclosure, there is provided a process for preparing the composition as disclosed herein, wherein the process is carried out at a temperature in a range of 60 to 160℃. In another embodiment of the present
30 disclosure, wherein mixing the graphene-rubber masterbatch with a rubber, a carbon black, and a first additive is carried out at a temperature in the range of 120 to 160

°C, and followed by addition of a second additive at a temperature in the range of 60 to 100 °C.
[0069] In an embodiment of the present disclosure, there is provided an article
comprising the graphene- rubber masterbatch or the tyre composition as disclosed
5 herein.
[0070] In an embodiment of the present disclosure, there is provided use of the graphene-rubber masterbatch obtained by the method as disclosed herein or the composition as disclosed herein.
[0071] Although the subject matter has been described in considerable detail with
10 reference to certain examples and implementations thereof, other implementations
are possible.
EXAMPLES
[0072] The disclosure will now be illustrated with working examples, which is
15 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 of ordinary skill in the art to which this disclosure belongs. Although methods and materials similar or equivalent to those described
20 herein can be used in the practice of the disclosed methods and compositions, the
exemplary methods, devices and materials are described herein.
[0073] The forthcoming examples explain how the present disclosure provides a process for preparing a rubber masterbatch comprising graphene and a rubber. The rubber masterbatch is henceforth referred to as graphene-rubber masterbatch
25 (GRMB). The present disclosure exemplifies the method for preparing the graphene-
rubber masterbatch. The method uses a two-roll mill for mixing graphite with rubber, resulting in graphene-rubber masterbatch. Further, the tyre composition is prepared by mixing carbon black and additives into the prepared masterbatch. The working examples show variation in the stress-strain properties of the prepared tyre
30 composition upon variation in the friction ratio of two-roll mill, and amount of
graphene-rubber masterbatch added.

[0074] For the purpose of the present disclosure, the following raw materials with
the specified grades/brands were used: a) Ribbed smoked sheet (RSS4) from VON
Bundit Co. Ltd., Thailand; b) Graphite from SD Fine Chemicals, India c) Carbon
black grades N134, from PCBL, India; d) Zinc oxide of W.S. Luxmi brand from JG
5 chemicals Pvt. Ltd; e) Stearic acid i.e stearic acid lubstric 995 from Godrej Industries
Ltd; f) Wax (MC wax) from Raj Petro Specialities Pvt. Ltd; g) Volcosulf 18
(Sulphur) from Solar Chemferts Pvt. Ltd; h) Accitard RE (CTP) from PMC Rubber
Chemicals India P.Ltd; i) CBS from Nocil Ltd., India; j) Phenol formaldehyde (PF)
resin from SI group, India; and k) PCTP (Pentachlorothiophenol) from Pukhraj
10 Group, India.
[0075] The two-roll mill of model SMX-LAB-613, make Santosh Rubber Machinery Pvt Ltd, was used in the present method.
EXAMPLE 1
Preparation of graphene-rubber masterbatch (GRMB) by two-roll mill
15 [0076] In an example, graphene-rubber masterbatch was prepared by mixing virgin
graphite with natural Rubber (RSS4) in a two-roll mill and the natural rubber to graphite weight ratio fed into the two-roll mill was 85:15 (w/w). This mixture was passed through two-roll mill and graphene-rubber masterbatch was obtained. The mixture was passed atleast twice to twenty times through the two-roll mill. The nip
20 gap of the two-roll mill was maintained at a distance of 0.5 cm in all the samples
prepared and the friction ratio in the two-roll mill was maintained in a range of 1:2 to 1:6. The friction ratio of two-roll mill was varied for each of the sample and corresponding graphene-rubber masterbatch samples prepared are shown in Table 1 below.
25 Table 1

Sample Friction ratio between
the two-rolls of the
two-roll mill Speed of the front roll speed (rpm) Speed of the back roll (rpm)
GRMB -1 1:2.5 13 32
GRMB -2 1:3.0 11 32

GRMB -3 1:3.5 9 32
GRMB -4 1:4.0 8 32
GRMB -5 1:4.5 7 32
GRMB -6 1:5.3 6 32
[0077] GRMB samples were prepared by varying the number of passes through the two-roll mill and the corresponding Mooney viscosity (ML1+4@100℃) were measured.
5 Preparation of tyre composition
[0078] The process of preparation of the tyre composition is explained herein. The
graphene-rubber masterbatch prepared as explained above was mixed with the
natural rubber RSS4, N134 and the first additives in a mixer followed by addition of
peptizer, activator, antioxidants, and processing aid to obtain a second mixture. The
10 second mixture was then cured to obtain the tyre composition. The addition of the
first additives was carried out at a temperature of 150°C, and addition of the second additives was carried out at a temperature of 100°C. The tyre compositions prepared by using different GRMBs are shown in Table 2 below.
Table 2

Ingredie nts Comp arative
Comp osition Compo sition 1 Composi tion 2 Composi tion 3 Composi tion 4 Composi tion 5 Composi tion 6
Natural rubber (RSS4) 100.00 94.33 94.33 94.33 94.33 94.33 94.33
PCTP 0.06 0.06 0.06 0.06 0.06 0.06 0.06
Carbon
Black (N134) 44.00 44.00 44.00 44.00 44.00 44.00 44.00
Zinc Oxide 3.50 3.50 3.50 3.50 3.50 3.50 3.50
Stearic Acid 2.00 2.00 2.00 2.00 2.00 2.00 2.00

Antioxid ant 2.70 2.70 2.70 2.70 2.70 2.70 2.70
MC wax 1.00 1.00 1.00 1.00 1.00 1.00 1.00
PF Resin 1.00 1.00 1.00 1.00 1.00 1.00 1.00
GRMB -1 0.00 6.67 0.00 0.00 0.00 0.00 0.00
GRMB -2 0.00 0.00 6.67 0.00 0.00 0.00 0.00
GRMB -3 0.00 0.00 0.00 6.67 0.00 0.00 0.00
GRMB -4 0.00 0.00 0.00 0.00 6.67 0.00 0.00
GRMB -5 0.00 0.00 0.00 0.00 0.00 6.67 0.00
GRMB -6 0.00 0.00 0.00 0.00 0.00 0.00 6.67
Sulphur 2.00 2.00 2.00 2.00 2.00 2.00 2.00
Accelera
tor
(CBS) 0.75 0.75 0.75 0.75 0.75 0.75 0.75
CTP 0.25 0.25 0.25 0.25 0.25 0.25 0.25
[0079] Comparative composition without any graphene-rubber masterbatch was prepared as a control sample.
[0080] The prepared compositions were further analysed to determine the tensile 5 modulus and elongation at break properties and the effect of various GRMBs prepared by varying the friction ratio was understood.
EXAMPLE 2
Effect of number of passes in the viscosity of GRMB sample 10 [0081] This example involves the study of the effect of number of passes in the Mooney viscosity (ML1+4 @100℃) of GRMB-3 sample prepared by mixing graphite and natural rubber by applying shear stress by passing it through two-roll

mill 20 times. The corresponding Mooney viscosity values measured are shown in
Figure 1. It could be observed that when the number of passes of GRMB through
two-roll mill increased, Mooney viscosity gradually decreased. After 20 passes,
viscosity became almost constant. Thus, to achieve the optimal Mooney Viscosity of
5 about 22 to 24 MU, the mixture of graphite and natural rubber was allowed to pass
through the two-roll mill for about 20 times.
Effect of friction ratio of GRMB samples in the tyre composition
[0082] This example involves the study of the effect of varying friction ratio in the
10 preparation of the graphene-rubber masterbatch in the two-roll mill in the
corresponding tyre composition.
[0083] The prepared tyre composition as explained above were then subjected to determine various properties including modulus at 50%, 100%, 200%, 300% and 400% elongation, tensile strength, and elongation at break and the obtained results
15 are in Table 3 below.
Table 3

Compa rative
Compo sition Compo sition 1 Compo sition 2 Compo sition 3 Compo sition 4 Compo sition 5 Compo sition 6
50% Modulus (MOD) (kg/cm2) 14.21 14.36 14.66 14.79 14.57 14.19 14.57
100% MOD (kg/cm2) 24.88 25.45 26.06 26.58 25.74 24.83 26.1
200% MOD (kg/cm2) 69.26 69.92 71.11 73.3 69.3 66.6 71.3
300% MOD (kg/cm2) 132.62 133.31 134.58 138.77 131.3 127.14 133.8
400% MOD (kg/cm2) 201.37 202.1 203.24 208.91 198.96 193.72 200.81
Tensile strength (kg/cm2) 305.61 303.27 304.82 308.11 299.85 302.5 298.72
Elongation at Break (%) 556.8 550.8 551.4 545.8 551.1 561.2 561.8

[0084] It could be observed from Table 3 that the tyre compositions prepared using GRMBs of the present disclosure exhibited improved stress-strain properties. In particular, the composition 3 comprising GRMB-3 prepared using two-roll with a friction ratio of 1:3.5 exhibited much improved properties. 5
EXAMPLE 3
Effect of different quantity of GRMB sample in the tyre composition
[0085] Each of the GRMB sample as prepared in Example 1 comprised 1 phr of
graphene with respect to 6.67 phr of the prepared graphene-rubber masterbatch
10 corresponding to 15% of graphene with respect to total weight of the graphene-
rubber masterbatch.
[0086] To understand the effect of different quantities of graphene in the tyre composition, varying quantities of GRMB-4 was used and the corresponding tyre compositions prepared are shown in Table 4 below. The amount of GRMB-4 was
15 varied from 3.33 phr containing 0.5 phr of graphene to 13.33 phr containing 2 phr of
graphene in the tyre composition.
Table 4

Composition 7 Composition 8 Composition 9 Composition 10 Composition 11
Natural
rubber
(RSS4) 94.33 94.33 94.33 94.33 94.33
PCTP 0.06 0.06 0.06 0.06 0.06
Carbon
Black
(N134) 44.00 44.00 44.00 44.00 44.00
Zinc Oxide 3.50 3.50 3.50 3.50 3.50
Stearic Acid 2.00 2.00 2.00 2.00 2.00
Antioxidant 2.70 2.70 2.70 2.70 2.70
MC wax 1.00 1.00 1.00 1.00 1.00
PF Resin 1.00 1.00 1.00 1.00 1.00

GRMB -4 3.33 5.00 6.67 10.00 13.33
Sulphur 2.00 2.00 2.00 2.00 2.00
Accelerator (CBS) 0.75 0.75 0.75 0.75 0.75
CTP 0.25 0.25 0.25 0.25 0.25
[0087] The prepared compositions were then subjected to determine various properties including modulus at 50%, 100%, 200%, 300% and 400% elongation, tensile strength, and elongation at break and the obtained results are tabulated in Table 5.
5 Table 5

Composition 7 Composition 8 Composition 9 Composition 10 Composition 11
50% MOD (kg/cm2) 15.66 16.07 16.38 17.04 16.62
100% MOD (kg/cm2) 28.78 29.65 30.29 31.54 30.97
200% MOD (kg/cm2) 83.03 84.57 85.64 87.4 86.23
300% MOD (kg/cm2) 154.59 156.13 157.89 159.67 158.03
400% MOD (kg/cm2) 227.21 228.57 231.68 233.24 231.03
TS (kg/cm2) 308.94 307.15 308.87 310.85 311.15
EB (%) 522.4 516.67 513.8 516.2 521.9
[0088] It could be observed that when the quantity of GRMB-4 in the compositions
(7-11) was increased from 3.33 phr to 13.33 phr, the stress-strain properties were
found to improve progressively. Thus, the higher loading of graphene provided
10 improved the properties of the tyre composition and the method of preparation of
graphene-rubber masterbatch of the present disclosure aided higher loading of graphene in the compositions.

EXAMPLE 4
Formation of graphene from graphite by using two-roll mill
[0089] To confirm the graphene formation in the graphene-rubber masterbatch
prepared by the method of the present disclosure, Atomic Force Microscopy (AFM)
5 was used to investigate the formation of graphene from virgin graphite. For this
purpose, 100 g of GRMB-4 was dissolved in 500 ml of toluene by stirring in a magnetic stirrer at 65°C for 4 hrs. This solution was then centrifuged in Remi-PR24 Research Centrifuge for 15 mins. The liquid obtained was slowly decanted off to a beaker. The process was repeated two times. The residue was thoroughly washed
10 twice with toluene followed by methanol and dried in an oven at 105°C for 30 mins.
The graphene thus separated was characterized by atomic force microscopy (AFM). [0090] Figure 2(a) shows the AFM image of graphite and Figure 2(b) indicate the AFM image of graphene formed in the graphene-rubber masterbatch. Similarly, graphene-rubber masterbatch prepared using co-rotating twin screw extruder was
15 analysed to understand the graphene formed and the corresponding AFM image is
shown in Figure 2(c). It could be observed that in Figure 2(c) strong kneading caused more breaking of graphene sheets and hence restricting higher loading of graphene in the masterbatch preparation. However, in the method of the present disclosure, breaking of graphene was lesser due to less intensive shearing action of the two-roll
20 mill, thereby facilitated higher loading of graphene and thus providing improved
properties.
ADVANTAGES OF THE PRESENT DISCLOSURE
[0091] The present disclosure provides a method of preparing a graphene-rubber
25 masterbatch using a two-roll mill. The preparation method is carried out by mixing
a graphite with a rubber and applying shear stress on it by passing through the two-roll mill. The shear stress created by varying the speed of front and back roll of two-roll mill (friction ratio) enables formation of graphenic layers from graphite, and rubber chain breaks into smaller lengths and enters between graphenic layer resulting
30 in exfoliation of graphitic layer. The graphene-rubber masterbatch obtained by the

method of the present disclosure thus comprises homogenously dispersed graphene in rubber.
[0092] The method allows direct conversion of graphite to graphene without any
expensive equipment, additional steps, and time-consuming process. The method
5 utilizes less intensive shearing action and hence enables higher loading of graphene
without deteriorating the properties. The present disclosure also provides tyre
composition comprising the graphene-rubber masterbatch with improved tensile
strength, modulus and elongation at break. Overall, the present disclosure provides
a simple, cost-effective and a time-saving process for the preparation of graphene-
10 rubber masterbatch and a tyre composition with improved stress-strain properties
and would open new opportunities in the realm of presently known processes for
producing rubber masterbatches.

I/We claim:
1. A method of preparing a graphene-rubber masterbatch, the method
comprising:
a. mixing graphite and at least one rubber in a two-roll mill to obtain a
5 mixture; and
b. passing the mixture through the two-roll mill to obtain the graphene-
rubber masterbatch,
wherein the two-roll mill is maintained in a friction ratio in a range of 1:2 to 1:6.
2. The method as claimed in claim 1, wherein step (b) is repeated at least once.
10 3. The method as claimed in claim 1, wherein the graphene-rubber masterbatch has Mooney viscosity in a range of 20 to 25 MU (ML1+4@100℃).
4. The method as claimed in claim 1, wherein passing the mixture through the two-
roll mill is carried out two to twenty times.
5. The method as claimed in claim 1, wherein the rubber and graphite are taken in
15 a weight ratio range of 80:20 to 95:5.
6. The method as claimed in claim 1, wherein the rubber is selected from natural
rubber, butadiene rubber, styrene butadiene rubber, or combinations thereof; and
the graphite is virgin graphite or oxidized graphite.
7. The method as claimed in claim 1, wherein the graphene-rubber masterbatch
20 comprises graphene in a weight range of 10 to 20% (w/w) with respect to total
weight of the graphene-rubber masterbatch.
8. A tyre composition comprising:
a. 2 to 15 phr of the graphene-rubber masterbatch obtained by the
method as claimed in claim 1;
25 b. 85 to 98 phr of a rubber;
c. 30 to 50 phr of a carbon black;
d. 0.01 to 15 phr of a first additive; and
e. 1 to 5 phr of a second additive.
9. The composition as claimed in claim 8, wherein the graphene-rubber
30 masterbatch comprises graphene in a weight range of 0.3 to 5 phr, with respect
to total weight of the graphene-rubber masterbatch.

10. The composition as claimed in claim 8, wherein the rubber is selected from
natural rubber, butadiene rubber, styrene butadiene rubber, or combinations
thereof; the carbon black is N134; the first additive is selected from a peptizer,
an activator, an antioxidant, a processing aid, or combinations thereof; and the
5 second additive is selected from a crosslinking agent, an accelerator, a retarder,
or combinations thereof.
11. The composition as claimed in claim 10, wherein the peptizer is selected from
2,2'-dithiobisbenzanilide (DBD), pentachlorothiophenol (PCTP), or
combinations thereof; the activator is selected from zinc oxide, stearic acid,
10 magnesium oxide, or combinations thereof; the antioxidant is selected from N-
1,3-dimethylbutyl-N'-phenyl-p-phenylenediamine (6PPD), microcrystalline (MC) wax, 2,2,4-trimethyl-1,2-dihydroquinoline (TMQ), or combinations thereof; the processing aid is selected from wood rosin, processing oil, or combinations thereof; the crosslinking agent is selected from sulphur, peroxide,
15 metal oxide, resin, or combinations thereof; the accelerator is selected from N-
cyclohexylbenzothiazole-2-sulphenamide (CBS), 2- mercaptobenzothiazole (MBT), bis(2-benzothiazole) disulfide (MBTS), diphenyl guanidine (DPG), diorthotolyl guanidine (DOTG), tetramethyl thiuram monosulfide (TMTM), tetramethyl thiuram disulfide (TMTD), diethyl dithiocarbamate (ZDEC),
20 dibutyl-dithiocarbamate (ZDBC), or combinations thereof; and the retarder is
selected from N- (cyclohexylthio) phthalimide (CTP), benzoic acid, salicylic acid, phthalic anhydride, or combinations thereof.
12. The composition as claimed in claim 8, wherein the composition exhibits tensile
strength in a range of 295 to 315 kg/cm2; elongation at break in a range of 500
25 to 580%; and modulus at 100% elongation in a range of 20 to 35 kg/cm2.
13. A process for preparing the composition as claimed in claim 8, the process
comprising: mixing the graphene-rubber masterbatch with a rubber, a
carbon black, a first additive and a second additive to obtain a second mixture;
and curing the second mixture to obtain the composition.
30 14. The process as claimed in claim 13, wherein the process is carried out at a temperature in a range of 60 to 160℃.

15. An article comprising the graphene-rubber masterbatch obtained by the method as claimed in claim 1 or the composition as claimed in claim 8.
16. Use of the graphene-rubber masterbatch obtained by the method as claimed in claim 1 or the composition as claimed in claim 8.