Description:FIELD OF THE INVENTION
The present invention relates to the field of polymer technology. The present invention in particular relates to an improved rubber composition for tyre innerliner and its method thereof.

BACKGROUND OF THE INVENTION
Tires serve to support the load of the vehicle, mitigate the impact from the road surface, and transmit the driving or braking force of the vehicle to the ground. In general, a tire is a composite of fiber/steel/rubber.

The innerliner is located on the inside of the tire instead of a tube, and it prevents air leakage and enables a pneumatic tire.

Recently, tubeless tires in which high-pressure air of about 30 to 40 psi is injected without using a tube is commonly used. An innerliner with high air tightness is disposed on the inner layer of the carcass.

Previously, tire innerliner containing rubber components such as butyl rubber or halobutyl rubber, which have relatively low air permeability were used. As the content and thickness of the rubber component increased, the total weight of the tire increased and the fuel efficiency of the vehicle decreased, and an air pocket was formed between the inner rubber of the carcass layer and the inner liner during the vulcanization process of the tire or the driving process of the vehicle. Changes in the shape and physical properties of the innerliner were also observed. Accordingly, various methods have been proposed to provide fuel efficiency by reducing the thickness and weight of the inner liner, and to reduce changes in the shape or physical properties of the inner liner that occur during tire vulcanization or driving process.
Reference made to the following:
Publication no. KR20160004487 relates to a rubber composition for a tire inner liner having improved inner air permeability through using graphene oxide and a rubber complex modified by a carboxylic acid group (-COOH); and a tire comprising the same.
The referred patent discusses about the tyre innerliner rubber composition having improved air permeability using graphene oxide and a rubber complex modified by a carboxylic acid group (-COOH) whereas present invention discusses about the use of Graphene nano platelet as a nano filler in tire innerliner rubber composition to improve low air permeability.

Publication no. WO2013107229 disclosed a composition for the inner liner of a tyre and an inner tube, and a preparation method thereof. The composition comprises the following two phases: (A) a continuous phase of graphene oxide/rubber composition with the graphene oxide/rubber composition being composed of three components, namely (1) graphene oxide, (2) a reactive rubber and (3) a solid rubber; and (B) a dispersion phase of an epoxy natural rubber or a thermoplastic resin. In the graphene oxide/rubber composition, the graphene oxide provides the necessary low gas permeability and provides significant reinforcement for the rubber composition; the epoxy natural rubber or thermoplastic resin is dispersed in the above mentioned graphene oxide/rubber composition and forms the structure of islands. The composition has low gas permeability, excellent mechanical performance, flexibility, and adhesion to adjacent rubber.
The referred patent discusses about the tyre innerliner or an innertube rubber composition comprising two phase: a) a continuous phase containing graphene oxide, a reactive rubber and a solid rubber and b) a dispersion phase of an epoxy natural rubber or a thermoplastic resin to attain low gas permeability, excellent mechanical performance, flexibility, and adhesion to adjacent rubber whereas present invention discusses about the use of Graphene nano platelet as a nano filler in tire innerliner to improve low air permeability.

Publication no. KR20140081075 relates to an inner liner of a tire according to the present invention includes: 100 parts by weight of polymer components including 30 to 70 parts by weight of a thermoplastic resin and 30 to 70 parts by weight of an elastomer; and 1 to 5 parts by weight of a graphene powder. The inner liner of a tire makes the weight of the tire lighter, simplifies the manufacturing process, and reduces the rotation resistance to increase fuel efficiency.
The referred patent discusses about the use of rubber composition containing 30 to 70 parts by weight of a thermoplastic resin and 30 to 70 parts by weight of an elastomer and 1 to 5 parts by weight of a graphene powder to make tire lighter and reduces the rotation resistance to increase fuel efficiency whereas present invention discusses about the use of Graphene nano platelet as a nano filler in tire innerliner to improve low air permeability.

Publication no. CN102558628 provides a graphene oxide/polymer composition for a tire liner and an inner tube and a preparation method of the graphene oxide/polymer composition. The graphene oxide/polymer composition for tire liner and inner tube comprises two phases respectively being a graphene oxide/rubber composition phase and an epoxy natural rubber (or thermoplastic resin) phase. In the graphene oxide/rubber composition phase, the graphene oxide provides the necessary low gas permeability and has obvious reinforcement on the rubber composition. The epoxy natural rubber or thermoplastic resin with low gas permeability is dispersed in the graphene oxide/rubber composition to form an island structure. Thus, the composition for the tire liner and the inner tube has excellent mechanical performance including the low gas permeability, rich flexibility and adhesion with the adjacent rubber.
The referred patent discusses about the tire innerliner rubber composition containing two phase: a) graphene oxide/rubber composition phase and b) an epoxy natural rubber (or thermoplastic resin) phase to have excellent mechanical performance including the low gas permeability, rich flexibility and adhesion with the adjacent rubber whereas present invention discusses about the use of Graphene nano platelet as a nano filler in tire innerliner to improve low air permeability.
Publication no. US2020238760 relates to a four-proofing safety tire including a conductive tread rubber layer, a supporting rubber layer, a tire explosion-proof rubber layer and a memory chip, wherein the conductive tread rubber layer can be formed by embedding, in the tread, a belt of narrow conductive rubber penetrated all the way to the inner cap ply or can be formed by adding carbon nanotubes or graphene conductive metamaterial to the tread formulation; the supporting rubber layer is a layer of rubber affixed on the inner wall of the sidewall when the tire is molded, which has a cross section with the shape of half slice of a willow leaf; the tire explosion-proof rubber layer is an explosion-proof layer added on the outer side of the inner liner provided on the inside of the ground-engaging tread of the tire; the memory chip is a special chip structure implanted in the sidewall portion of the tire without affecting the performance of the tire. The anti-static effect of the conductive tread formulation for the tread is excellent; the chip implantation technology can make it possible to trace the product information at any time; a layer of highly stable and highly viscous fluid coating inside the tire prevents air leakage; the support rubber is provided on the inner wall of the sidewall, which effectively reduces the damage to the tire caused by puncture to improve the air-captive property of the tire.
The referred patent relates to a four-proofing safety tire including a supporting rubber layer, a tire explosion-proof rubber layer , a memory chip and conductive tread rubber layer in which graphene conductive metamaterial to the tread formulation whereas present invention discusses about the use of Graphene nano platelet as a nano filler in tire innerliner to improve low air permeability.

Publication no. IN1171/DEL/2015 relates to rubber reclaim material exhibiting excellent processability but compromises compound properties, whereas alternative options of recycled material are either cost prohibitive, degrade compound performance, or lead to unacceptable processing behavior. The renewed rubber of this invention can be processed much more easily than conventional recycled rubber compositions. It also consistently exhibits an array of better overall cured rubber properties with only minimal variations in characteristics, by using feed stocks made by various grinding methods. In the chemical functionalization of the renewed rubber compositions of this invention, the sulfur-sulfur bonds in micronized rubber powder are broken to partially devulcanize the rubber, with only a minimal number of carbon-carbon double bonds in the backbone of the polymer being broken. This allows for the renewed rubber of this invention to be used in rubber formulations that are used in manufacturing a wide array of rubber products, including tires, power transmission belts, conveyor belts, hoses, and a wide array of other products. The present invention more specifically discloses a method for manufacturing an environmentally friendly, chemically functionalized, renewed rubber composition having a highly desirable combination of physical properties and which exhibits excellent processability comprising the steps of (1) blending a micronized rubber powder with a processing aid and a chemical functionalizing agent to produce a blended mixture; (2) processing the blended mixture under conditions of high shear and low temperature to produce a reacted mixture; (3) adding a stabilizer to the reacted mixture to produce the chemically functionalized renewed rubber composition.
The referred patent discusses about the use of reclaimed cross-linked elastomeric material such as micronized rubber powder which performs the role of an uncured elastomer rather than merely serving the function of a filler whereas present invention discusses about the use of Graphene nano platelet as a nano filler in tire innerliner to improve low air permeability.

Publication no. IN1171/DELNP/2012 relates to a copolymer formed from an isoolefin having from 4 to 7 carbon atoms and an alkylstyrene. The copolymer has a substantially homogeneous compositional distribution. The copolymer has from about 8 to about 12 wt% of alkylstyrene and at least 85 wt% of isoolefin. The copolymer is preferably halogenated with about 1.1 to about 1.5 wt% of a halogen. The copolymer may in elastomeric nanocomposites. To obtain a good dispersion of the nanoclay in a formulated compound, at least one cure accelerator is selected from the group consisting of mercaptobenzothiazole disulfide, mercaptobenzothiazole, cyclohexyl benzothiazole disulfide, dibutyl thiourea, tetramethylthiuram disulfide, 4-4-dithiodimropholine, zinc dimethyldithiocarbamate, and zinc dibutylphosphorodithiate.
The referred patent discusses about the use of copolymer of isoolefin and alkylstyrene with any accelerator from group consisting of mercaptobenzothiazole disulfide, mercaptobenzothiazole, cyclohexyl benzothiazole disulfide, dibutyl thiourea, tetramethylthiuram disulfide, 4-4-dithiodimropholine, zinc dimethyldithiocarbamate, and zinc dibutylphosphorodithiate to have uniform dispersion of nanoclay whereas present invention discusses about the use of Graphene nano platelet as a nano filler in tire innerliner to improve low air permeability.

Publication no. CN209563519 discloses a lining with a graphene heating module. The fabric comprises a thermal insulation layer, a graphene heating module and an inner fabric, the heat preservation layer comprises two layers of sewing fabric and graphene flocculus filler arranged in the two layers of sewing fabric. The graphene heating module is arranged on the sewn fabric of the thermal insulation layer; wherein the inner fabric is attached to the outer side face of the heat preservation layer, the graphene heating module is arranged on the inner side face of the heat preservation layer and below the inner fabric, a polyester fiber layer is further arranged on the outer side of the heat preservation layer, and the two layers of sewn fabric and the inner fabric are graphene fiber fabric. The far-infrared health-care heating pad not only has antibacterial, bacteriostatic, dehumidifying, antistatic, far-infrared health-care, warm-keeping and magnetic therapy effects, but also has the advantages of light weight, uniform heating, high heating efficiency, low energy consumption, recyclability, comfortable touch feeling and the like.
The referred patent discusses about use of graphene heating module as wearable electricity fever magnetic therapy textile material along with inner fabric, heat preservation layer (sewing fabric and graphene fabric) whereas present invention discusses about the use of Graphene nano platelet as a nano filler in tire innerliner to improve low air permeability.

Publication no. WO2013090464 relates to the compositions comprising graphene sheets. at least one reinforcing agent, and at least one rubber. The compositions may further comprise carbon black. The compositions may be formed into articles including tire components.
The referred patent discusses about the use of graphene sheets along with carbon black reinforcing filler in tyre components whereas present invention discusses about the use of Graphene nano platelet as a nano filler in tire innerliner to improve low air permeability.

Publication no. US2015368451 relates to a tyre innerliner compound having a polymer base composed at least partly of butyl rubber and/or halobutyl rubber; a filler system; and a curing system. The filler system has 60 to 80 phr of a silicon-based lamellar mineral filler; and 8 to 30 phr of a carbon black mixture composed of a first carbon black with a nitrogen-absorption-measured surface area of 21 to 39 m2/g, and a second carbon black with a nitrogen-absorption-measured surface area of 70 to 120 m2/g.
The referred patent discusses about the use of rubber composition butyl rubber and/or halobutyl rubber along with silicon-based lamellar mineral filler; and phr of a carbon black mixture to improve low air impermeability whereas present invention discusses about the use of Graphene nano platelet as a nano filler in tire innerliner to improve low air permeability.

However, any previously known method has limitations in maintaining excellent air permeability and moldability of the tire while sufficiently reducing the thickness and weight of the inner liner. Also, the inner liner obtained by the conventional method may be used in the manufacturing process or driving process of the tire. There was a problem in that it did not have sufficient fatigue resistance, such as cracks occurring due to repeated deformation in the back. Hence there needed an innerliner rubber composition to improve low air permeability.
In order to overcome above listed prior art, the present invention aims to provide an innerliner rubber composition and its method of preparation which improves low air permeability.

OBJECTS OF THE INVENTION
The principal object of the present invention is to provide an innerliner rubber composition to improve low air permeability and its method thereof.

Yet another object of the present invention is to provide chlorobutyl rubber and natural rubber blend based tyre innerliner rubber composition.

Another object of the present invention is to provide an innerliner rubber composition containing graphene nano platelet as a nano filler.

Another object of the present invention is to provide an innerliner rubber composition containing graphene nano platelet is added along with reinforcing filler carbon black or graphene nano platelet is replaced by reinforcing filler carbon black.

SUMMARY OF THE INVENTION
One or more problems of the conventional prior arts may be overcome by various embodiments of the present invention.

It is primary aspect of the present invention to provide a tyre inner liner rubber composition, comprising of:
Polymer matrix – 100 phr;
Reinforcing filler – 40 to 60 phr;
Nanofiller – 10 to 20 phr;
Vulcanization activator – 1.5 to 2.65 phr;
Anti-degradant – 0 to 1.50 phr;
Vulcanization agent – 1.5 to 2.0 phr;
Homogenizing agent – 5 to 7 phr;
Process aid – 1.0 to 5.0 phr; and
Primary accelerator – 2.0-2.50 phr,
wherein the nanofiller is graphene nano platelet with thickness of
5 – 10 nm and 5-10 average no. of layers having BET surface area 60 to 200 m2/gm.

It is another aspect of the present invention to provide a tyre inner liner rubber composition, wherein the polymer matrix comprises of rubbers selected from Natural rubber and Chlorobutyl rubber, in a weight ratio of 25:75 phr.

It is another aspect of the present invention to provide a tyre inner liner rubber composition, wherein the reinforcing filler is carbon black.

It is another aspect of the present invention to provide a tyre inner liner rubber composition, wherein the vulcanization activator is zinc oxide and stearic acid, in a weight ratio of 2.15:1.50.

It is another aspect of the present invention to provide a tyre inner liner rubber composition, wherein the anti-degradant is 6PPD (N-(1,3-dimethylbutyl)-N’-phenyl-p-phenylenediamine).

It is another aspect of the present invention to provide a tyre inner liner rubber composition, wherein the vulcanization agent is sulphur.

It is another aspect of the present invention to provide a tyre inner liner rubber composition, wherein the primary accelerator is N-tert-butyl-2-benzothiazole sulfenamide (TBBS).

It is another aspect of the present invention to provide a tyre inner liner rubber composition, wherein the homogenizing agent is Struktol 40 MS.
It is another aspect of the present invention to provide a tyre inner liner rubber composition, wherein the process aid is selected from MES oil, aromatic oil, TDAE oil, castor oil or any other naturally occurring oils.

It is another aspect of the present invention to provide a method for preparation of tyre inner liner rubber composition, comprising of steps:
Step I - Preparation of master batch:
Mixing of polymers and homogenizing agent for 30 seconds using a Banbury mixer,
Adding of 100% of the reinforcing filler carbon black, graphene nano platelet nano filler, anti-degradant 6PPD, stearic acid, process aid and mixing for 300-400 seconds,
Dumping of the rubber compound and sheet-out using a two-roll mill;
Step II – Preparation of final batch:
Mixing of masterbatch compound with cure activator zinc oxide, vulcanization agent sulphur and primary accelerator TBBS for 120-180 seconds, and
Dumping of the rubber compound and sheet-out using two-roll mill,
wherein the polymer matrix comprises of rubbers selected from Natural rubber and Chlorobutyl rubber, in a weight ratio of 25:75 phr, and
wherein the nanofiller is graphene nano platelet with thickness of 5 – 10 nm and 5-10 average no. of layers having BET surface area 60 to 200 m2/gm.

It is another aspect of the present invention to provide a method for preparation of tyre inner liner rubber composition, wherein the master batch processing parameter includes rotation speed of the Banbury mixer at 60 rpm and head temperature of Banbury maintained between 18 and 25 degree Celsius.

DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to a rubber composition according to Table 1 intended for the manufacture thereof and to provide low air permeability in tyre innerliner. The rubber composition for tyre innerliner according to the invention, comprises of:
a.The tyre innerliner rubber composition according to the present invention comprising of 25 parts by weight of Natural rubber and 75 parts by weight of chlorobutyl rubber blend (NR:CIIR). The natural rubber used in present invention is ISNR 20 with the Mooney Viscosity, ML (1+4) @100°C is 74 MU. Also, other grades of NR like RSS (Ribbed Smoke Sheet), NR constant viscosity grades can be used.
b. Reinforcing filler, Carbon black of ASTM grade N326 having the Iodine adsorption No. value in the range of 77 to 87 mg/gm, tinting strength value in the range of 106 to 116% ITRB. Also, any other grades of carbon black which is suitable for tyre innerliner application namely N660, N330, N375, N550, N772 can be used.
c. Graphene nano platelets nano-filler with thickness of 5 to 10 nm and 5 to 10 average no. of layers, and its average lateral dimension (X&Y) is 10 µm, tensile modulus (parallel to surface) is greater than 1000 Gpa & tensile strength (Parallel to surface) is greater than 5 Gpa is used to obtain low air permeability of tyre innerliner.
d. MES Oil - Mild Extracted Solvate (MES) is used to improve the processability of rubber compounds or any other oils aromatic oil, TDAE oil, castor oil or any other naturally occurring oils can be used.
e. Zinc oxide and stearic acid are added to form zinc soap, improves the solubility of zinc oxide in the compound, and with the accelerator to form a complex, this complex reacts with sulphur to produce a strong cure activating system.
f. Struktol 40 MS improves the homogeneity of elastomers of different polarity and viscosity.
g. Antidegradant 6PPD is added to the rubber composition to provide resistance to thermo-oxidative aging of elastomers. Also, a skilled person can be used the present invention tyre innerliner rubber composition without using antidegradant.
h. The vulcanization system used in the present invention is based on sulphur and a primary accelerator, N-tert-butyl-2-benzothiazole sulfenamide (TBBS).
Table 1: Rubber compositions in phr
Ingredients C1, Control Formulation related to invention
F1, phr F2, phr F3, phr
Chlorobutyl Rubber 1 75.00 75.00 75.00 75.00
Natural Rubber, ISNR 202 25.00 25.00 25.00 25.00
N3263 53.00 53.00 53.00 43.00
Graphene Nanoplatelets4 10.00 20.00 10.00
MES Oil5 3.00 3.00 3.00 3.00
Zinc Oxide6 2.15 2.15 2.15 2.15
Stearic Acid7 1.50 1.50 1.50 1.50
Struktol 40 MS8 6.30 6.30 6.30 6.30
6PPD9 1.23 1.23 1.23 1.23
TBBS10 2.25 2.25 2.25 2.25
Sulphur11 1.75 1.75 1.75 1.75
Total, Phr 171.18 181.18 191.18 171.18

1. Chlorobutyl Rubber – It is from Reliance Sibur Elastomers Pvt Ltd, Gujarat.
2. Natural Rubber - Indian Standard Natural Rubber ISNR 20 with the Mooney Viscosity, ML (1+4) @100°C is 76 MU. from Kurian Abraham (P) Ltd, Kanyakumari.
3. N326 - ASTM Grade carbon black N326 from Continental carbon, Ghaziabad.
4. Graphene nano platelets – It is from Techinstro Innovations, Maharashtra.
5. MES Oil-Indian Oil Corporation Limited, India
6. Zinc oxide-It is from Pondy Oxides & chemicals Ltd, Kancheepuram, Tamilnadu.
7. Stearic acid- Stearic Acid from 3F Industries, Andhra Pradhesh.
8. Struktol 40 MS-It is from Schill+Seilacher Struktol GMBH, Germany.
9. 6PPD (N-(1, 3-dimethylbutyl)-N’-phenyl-p-phenylenediamine)- It is from NOCIL Limited, Mumbai.
10. TBBS -It is from Nocil Limited, Mumbai.
11. Sulphur- It is from The Standard Chemical Co Pvt Ltd, Tamilnadu

Method of preparation of tyre innerliner rubber composition:
Mixing Sequence:
Using a Banbury mixer, a rubber composition prepared by a thermo-mechanical process is as follows:
Preparation of master batch:
Step I: Preparation of master batch has been performed with the rotation speed of the mixer at 60 rpm and with the head temperature of the Banbury maintained between 18 to 25°C a) Mixing chamber has been charged with the selected polymer and homogenizing agent struktol 40MS, and allowed to mix for 30 seconds b) Further by adding, 100% of the reinforcing filler carbon black, antidegradant 6PPD, graphene nano platelet nano filler and stearic acid, process aid and allow it to mix for 300 to 400 seconds and the compound has been dumped and sheeted out in the laboratory two-roll mill.

Step II: Preparation of Final Batch: Mixing of master batch compound with cure activator zinc oxide, vulcanization agent sulphur and primary accelerator and allowed to mix for 120 to 180 seconds and the rubber compound has been dumped and sheeted out in laboratory two-roll mill.
Characterization of Cured Rubber Vulcanizate and Uncured Rubber Compound:
The Rubber compound and Rubber vulcanizate properties are listed in Table 2 mentioned below-
Measurements and Tests:
Better processability (Process Requirements) of a Rubber Compound:
M1. Mooney Scorch Characteristics (pre vulcanization characteristics using large rotor) for processability:
The Mooney Scorch measurements are carried out in a Mooney Viscometer (MV 2000 Alpha technologies, USA) according to ASTM D1646. t5 indicates the time to scorch (MV+5) which indicates the processing properties (process safety).

M2: Permeability of the Rubber Vulcanizate:
Oxygen Transmission rate of the rubber vulcanizate in accordance with ASTM F 1927 using permeation test analyzer Macon make, Model OTR_MH-2/21.

Table 2: Rubber compound and Rubber vulcanizate properties
Properties Control
Composition Rubber Composition related to invention Rubber Composition related to invention against control rubber composition
C1, phr F1,
Phr F2, phr F3, phr F1, Index F2, Index F3, Index
M1. Better Processability
Mooney Scorch @ 125°C
t5, minutes: seconds:
Ideal value is 15 minutes 20.40 20.17 16.18 22.27 - - -
M2: Air permeability of the Rubber Vulcanizate
Oxygen transmissibility rate, cc/ (m². day)
Lower the index value is better. 13.326 12.175 5.530 11.807 91.36 41.50 88.60

RESULTS:
The objective of these tests is to measure the improved properties of the tyre innerliner rubber composition related to the invention against control rubber composition. For this, control composition C1 prepared based on CIIR:NR (75 phr:25 phr) diblend containing 53 phr of N326 reinforcing filler carbon black is compared against F1, F2 & F3 rubber composition related to invention based on based on CIIR:NR (75 phr:25 phr) diblend containing 53 phr of N326 reinforcing filler carbon black and 1 to 20 phr of graphene nano platelets are prepared and evaluated.

The present invention provides 100 parts by weight of tyre innerliner rubber compositions F1 & F2, CIIR:NR (75 phr:25 phr) diblend based rubber composition containing 53 phr of N326 carbon black along with 10 phr & 20 phr of Graphene nano platelets gave better processing characteristics having scorch time values, t5 are 20.17 minutes & 16.18 minutes respectively when compared to CIIR:NR (75 phr:25 phr) diblend based rubber composition containing 53 phr of N326 reinforcing filler carbon black C1, control rubber composition. Note: Ideal value of scorch time, t5 value is 15 minutes. Also, 100 parts by weight of tyre innerliner rubber composition F3, CIIR:NR (75 phr:25 phr) diblend based rubber composition containing 53 phr of N326 carbon black replaced with 10 phr of Graphene nano platelets gave better processing characteristics having scorch time value, t5 is 22.27 minutes when compared to CIIR:NR (75 phr:25 phr) diblend based rubber composition containing 53 phr of N326 reinforcing filler carbon black C1, control rubber composition.

The present invention provides 100 parts by weight of tyre innerliner rubber compositions F1 & F2, CIIR:NR (75 phr:25 phr) diblend based rubber composition containing 53 phr of N326 carbon black along with 10 phr & 20 phr of Graphene nano platelets gave better processing characteristics having scorch time, t5 values are 20.17 minutes & 16.18 minutes respectively when compared to CIIR:NR (75 phr:25 phr) diblend based rubber composition containing 53 phr of N326 reinforcing filler carbon black C1, control rubber composition. Note: Ideal value of scorch time, t5 value is 15 minutes. Also, 100 parts by weight of tyre innerliner rubber composition F3, CIIR:NR (75 phr:25 phr) diblend based rubber composition containing 53 phr of N326 carbon black replaced with 10 phr of Graphene nano platelets gave better processing characteristics having scorch time, t5 value is 22.27 minutes when compared to CIIR:NR (75 phr:25 phr) diblend based rubber composition containing 53 phr of N326 reinforcing filler carbon black C1, control rubber composition.

The present invention provides 100 parts by weight of tyre innerliner rubber compositions F1 & F2, CIIR:NR (75 phr:25 phr) diblend based rubber composition containing 53 phr of N326 carbon black along with 10 phr & 20 phr of Graphene nano platelets provides 8.64% & 58.50% low air permeability when compared to CIIR:NR (75 phr:25 phr) diblend based rubber composition containing 53 phr of N326 reinforcing filler carbon black C1, control rubber composition. Also, 100 parts by weight of tyre innerliner rubber composition F3, CIIR:NR (75 phr:25 phr) diblend based rubber composition containing 53 phr of N326 carbon black replaced with 10 phr of Graphene nano platelets provides 11.40% low air permeability when compared to CIIR:NR (75 phr:25 phr) diblend based rubber composition containing 53 phr of N326 reinforcing filler carbon black C1, control rubber composition.

Hence, the present invention provides 100 parts by weight of tyre innerliner rubber composition F1, F2 & F3 CIIR:NR (75 phr:25 phr) diblend based rubber composition containing reinforcing filler 53 phr of N326 along with 1 to 20 phr of graphene nano platelets or replaced with 1 to 20 phr of graphene nano platelets with reinforcing filler carbon black provides low air permeability along with better processing properties. , Claims:WE CLAIM:
1. A tyre inner liner rubber composition, comprising of:
Polymer matrix – 100 phr;
Reinforcing filler – 40 to 60 phr;
Nanofiller – 10 to 20 phr;
Vulcanization activator – 1.5 to 2.65 phr;
Anti-degradant – 0 to 1.5 phr;
Vulcanization agent – 1.5 to 2.0 phr;
Homogenizing agent – 5 to 7 phr;
Process aid – 1 to 5 phr; and
Primary accelerator – 2-2.5 phr,
wherein the nanofiller is graphene nano platelet with thickness of
5 – 10 nm and 5-10 average no. of layers having BET surface area 60 to 200 m2/gm.

2. The tyre inner liner rubber composition as claimed in claim 1, wherein the polymer matrix comprises of rubbers selected from Natural rubber and Chlorobutyl rubber, in a weight ratio of 25:75 phr.

3. The tyre inner liner rubber composition as claimed in claim 1, wherein the reinforcing filler is carbon black.

4. The tyre inner liner rubber composition as claimed in claim 1, wherein the vulcanization activator is zinc oxide and stearic acid, in a weight ratio of 2.15:1.50.

5. The tyre inner liner rubber composition as claimed in claim 1, wherein the anti-degradant is 6PPD (N-(1,3-dimethylbutyl)-N’-phenyl-p-phenylenediamine).

6. The tyre inner liner rubber composition as claimed in claim 1, wherein the vulcanization agent is sulphur.

7. The tyre inner liner rubber composition as claimed in claim 1, wherein the primary accelerator is N-tert-butyl-2-benzothiazole sulfenamide (TBBS).

8. The tyre inner liner rubber composition as claimed in claim 1, wherein the homogenizing agent is Struktol 40 MS.

9. The tyre inner liner rubber composition as claimed in claim 1, wherein the process aid is selected from MES oil. , aromatic oil, TDAE oil, castor oil or any other naturally occurring oils.

10. A method for preparation of tyre inner liner rubber composition, comprising of steps:
Step I - Preparation of master batch:
Mixing of polymers and homogenizing agent for 30 seconds using a Banbury mixer,
Adding of 100% of the reinforcing filler carbon black, graphene nano platelet nano filler, anti-degradant 6PPD, cure activators zinc oxide and stearic acid, process aid and mixing for 300-400 seconds,
Dumping of the rubber compound and sheet-out using a two-roll mill;
Step II – Preparation of final batch:
Mixing of masterbatch compound with cure activator zinc oxide, vulcanization agent sulphur and primary accelerator TBBS for 120-180 seconds, and
Dumping of the rubber compound and sheet-out using two-roll mill,
wherein the polymer matrix comprises of rubbers selected from Natural rubber and Chlorobutyl rubber, in a weight ratio of 25:75 phr, and
wherein the nanofiller is graphene nano platelet with thickness of 5 – 10 nm and 5-10 average no. of layers having BET surface area 60 to 200 m2/gm.

11. The method for preparation of tyre inner liner rubber composition as claimed in claim 10, wherein the master batch processing parameter includes rotation speed of the Banbury mixer at 60 rpm and head temperature of Banbury maintained between 18 and 25 degree Celsius.