DESC:FIELD OF INVENTION
The present invention relates to the field of tyre innerliner composition particularly, the present invention relates to a tyre innerliner composition and its method of preparation using oil recovered from waste tyre.

BACKGROUND OF INVENTION
Tubeless tires have an inner surface of low air permeability so as to prevent the tire from deflating and to protect the sensitive internal regions of said tire from the ingress of oxygen and water, such as the plies containing oxidation-sensitive metal cords, this protection, improving the endurance of the tire. At the present time, such protection of the inner surface of tires is generally achieved by inner liners consisting of elastomeric compositions based on butyl rubber. However, the air impermeability performance of butyl rubbers is linked to a not inconsiderable minimum thickness (of the order of a millimetre) and therefore to a certain weight, which does not make it possible to efficiently meet these new requirements.
Thus, it is necessary to add reinforcing fillers, such as carbon black, to the elastomeric inner liner composition in order to improve its impermeability. However, in large quantities, these reinforcing fillers impair certain properties of the composition both in the uncured state: difficulty in processing the uncured composition, commonly referred to as a “processability” difficulty, and in the cured state: degradation of mechanical properties, especially reduction in the flexural strength. The introduction of plasticizers of the oil type makes it possible to overcome these processing and mechanical property aspects.
Various solutions have been envisaged for overcoming these drawbacks, in particular by using other types of fillers, often known as smectites, to be added to the reinforcing fillers.
Reference made to the following:
Publication no. US2015284548 relates to the tire, the inner liner of which comprises a rubber composition based on at least predominantly a highly unsaturated diene elastomer, a reinforcing organic filler, graphite, chalk, a plasticizing hydrocarbon resin, the glass transition temperature, Tg, of which is greater than 20° C. and the softening point of which is less than 170° C. The use of such a composition in the inner liner of the tire, including graphite and a non-reinforcing filler of chalk type, makes it possible to notably improve the airtightness properties with respect to a control composition which comprises only graphite and which already performs very well in this aspect, but also with respect to a control composition conventionally used in the inner liners of tires, while maintaining a good level of the stiffness and processability properties as the conventional control compositions.
Publication no. WO2013170358 relates to an integrated scrap tire pyrolysis plant can be built to process scrap tires. The recovered carbon black can be used in rubber and plastic industries. Oil and gas from the pyrolysis process can further be used in the production of virgin carbon black. Natural rubber is a sustainable feedstock for the manufacture of tires, making the manufacture of virgin carbon black partially sustainable. A very low PAH carbon black can be produced by limiting the exit temperature of carbon black and tail gas prior to leaving the reaction chamber.
Reference may be made to an article entitled “Evaluation of pyrolytic oil from scrap tires as plasticizer of rubber compounds” by Franco Cataldo, Progress in Rubber, Plastics and Recycling Technology (Vol. 22, Issue 4) October-December 2006 Metadata which talks about a heavy fraction of oil obtained from pyrolysis of rubber crumb derived from scrap tires was studied by H-NMR and FT-IR spectroscopy in comparison to a distillate aromatic extract (DAE) derived from petroleum and currently used as plasticizer in rubber mixes. The spectral data suggest a rough chemical analogy between the two oils although the viscosity and the density of the pyrolysis oil are significantly lower than that of the aromatic extract suggesting a significantly lower average molecular weight for the pyrolytic oil in comparison to the reference DAE oil. The two oils were tested at 10 and 15 phr level in a NR-based formulation and the cure kinetics and the mechanical properties of the rubber compounds have been measured. The pyrolytic oil gives accelerated cure kinetics, reduced scorch safety and lower compound viscosity in comparison to reference compounds with DAE oil. The mechanical properties of the cured compounds prepared with pyrolysis oil from scrap tires appear similar to the reference compounds prepared with DAE oil. However, the ageing resistance of the pyrolysis oil are worse than the reference compound with DAE oil.
Reference may be made to an article entitled “Oil from tyre pyrolysis as a plasticizer in rubber compounds, by Cezary Debek, published 2019 which talks about the results of research on the possibility of using as plasticizers of rubber compounds the heavy fractions of pyrolytic oil obtained in the industrial process of pyrolysis of car tyres. The content of carcinogenic polycyclic aromatic hydrocarbons (PAHs) in the obtained pyrolytic plasticizers was determined. Compounds and vulcanizates of styrene- butadiene rubber (SBR) containing the above plasticizers as well as commercial petroleum derivatives’ plasticizers were prepared for comparative purposes. The basic properties of compounds and vulcanizates containing pyrolytic plasticizers were investigated. The research showed that one fraction of pyrolysis oil meet the requirements of the permitted content of PAHs. SBR blends and vulcanizates have similar properties as in the case of commercial plasticizers.
Hence there needed a low-cost tyre innerliner composition which provides better processability.
In order to overcome above listed prior art, the present invention aims to provide a tyre innerliner composition using oil recovered from waste tyre and its method of preparation. The present invention uses the tyre pyrolysis oil in tyre innerliner rubber composition to improve polymer filler interaction along with cost saving and to provide better processability.

OBJECTS OF THE INVENTION:
The principal object of the present invention is to provide a tyre innerliner composition using oil recovered from waste tyre.
Another object of the present invention is to provide a method of preparing tyre innerliner composition using tyre pyrolysis oil.
Yet another object of the present invention is to provide cost effective tyre innerliner rubber composition which provides better processability.
At the outset of the description that follows, it is to be understood that the ensuing description only illustrates a particular form of this invention. However, such a particular form is only an exemplary embodiment and is not intended to be taken restrictively to imply any limitation on the scope of the present invention.

SUMMARY OF THE INVENTION:
The present invention provides a tire innerliner composition incorporating oil obtained from the pyrolysis of waste tires. This composition aims to enhance processability and reduce costs associated with tire manufacturing.
In some aspects of the present invention, the tire innerliner composition includes Natural Rubber: 40.0-90.0 phr
SBR 1723: 5.0-70.0 phr (optional)
SBR 1502: 5.0-70.0 phr
Carbon Black: 1.0-85.0 phr Butyl Rubber: 1.0-30.0 phr
Process Aid (Oil): 1.0-15.0 phr (optional) Pyrolysis Oil: 1.0-50.0 phr Antidegradant (6PPD): 0.1-4.0 phr
Vulcanization Agent (Sulphur): 0.5-3.0 phr Primary Accelerator (CBS): 0.5-3.0 phr Method of Preparation:
Master Batch Preparation:
i) Mixing rubbers and 50% of the tire pyrolysis oil;
ii) Adding carbon black, remaining pyrolysis oil, and rubber chemicals;
iii) Dumping the mixture at a temperature range of 135°C to 165°C;
iv) Sheeting out in a laboratory two-roll mill. Final Batch Preparation:
i) Mixing the master batch with accelerators and vulcanization agents;
ii) Dumping the mixture at a temperature range of 95°C to 115°C; and
iii) Sheeting out in a laboratory two-roll mill
In some embodiment of the present invention, Oxygen Transmission Rate is measured according to ASTM F1927.
In some embodiment of the present invention, the Payne Effect evaluated using a Rubber Process Analyzer to assess filler-filler and polymer-filler interactions.

DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to a tire innerliner composition and its method of preparation using oil recovered from waste tires. Specifically, the oil obtained from the pyrolysis of waste tires is utilized in the tire innerliner component.
The composition for tire treads includes one or more rubbers/polymer matrix/elastomeric matrix, reinforcing fillers, activators, anti-degradants, a vulcanization agent, and primary accelerator. The rubber compositions are detailed in Table 1.
The present invention incorporates tire pyrolysis oil into the tire innerliner rubber composition to enhance processability and reduce costs. This pyrolysis oil is not derived from crude oil. During the pyrolysis of tires, the polymers are broken down to produce hydrocarbon oil, resulting in a high aromatic content in the oil.
Processing oils offer lubrication between polymer chains without causing any chemical changes. In binary and ternary rubber blend systems, the concept of wetting is widely employed to identify filler localization and the interaction between rubber and filler.
Tire pyrolysis oil, which contains aromatic content, enhances rubber-filler interaction. Non-oil extended SBR is used in conjunction with pyrolysis oil for this purpose.
Table 1: Rubber Composition in phr

Ingredients Control C1 F1 F2
Natural Rubber 50.00 50.00 50.00
SBR 1723 61.85 - -
SBR 1502 - 45.00 45.00
Butyl Rubber 5.00 5.00 5.00
Carbon Black N326 65.00 65.00 65.00
TDAE Oil 15.00 - -
Tyre Pyrolysis oil - 26.90 21.90
6PPD 0.50 0.50 0.50
Stearic Acid 1.00 1.00 1.00
Strucktol 40 MS 1.00 1.00 1.00
Sulphur 1.60 1.60 1.60
CBS 0.90 0.90 0.90
Zinc Oxide 2.50 2.50 2.50

Properties Control Formulation related to Invention Index
C1 F1 F2 F1 F2
M1. Processability of Rubber Vulcanizate
t5, minutes: minutes
(t5 value greater than 15 minutes is good for processability) 19.08 21.30 20.03 - -
M2. Payne Effect of Rubber Compound
Payne Effect (G’@ 0.07% - G’@ 10%) Mpa (Lower the index value is better 0.64 0.45 0.61 70.31 95.31
M3. Barrier Properties of Rubber Vulcanizate
Oxygen Transmission Rate (OTR), cc/m2.gm
(Lower the index value is better) 209.119 180.769 171.547 86.44 82.03

1. Natural Rubber – Natural rubber ISNR 20 from Alpha Rub Trading Manufacturing, Kerala.
2. SBR 1723 – Styrene butadiene rubber having 37.5 phr oil extended with TDAE oil & 23.5 weight % of Bound styrene content from Reliance Industries, Gujarat.
3. SBR 1502 – It is non-oil extended styrene butadiene rubber containing 23.4% bound styrene content from Kumho Petrochemicals, Korea
4. Butyl Rubber –It is from Reliance Sibur Elastomers Pvt ltd, Gujarat.
5. Carbon Black –It is N326 ASTM grade carbon black having iodine adsorption number ranges from 77 to 87 mg/gm, oil absorption number ranges from 67 to 77 gm/100 gm, nitrogen surface area (specific surface area) ranges from 73 to 85 m2/gm and tinting strength ranges from 106 to 116 % ITRB and it is from Himadri Carbon Black, West Bengal.
6. TDAE Oil –Treated Distillate Aromatic Extract (TDAE) is a type of rubber process oil used to improve the processing of rubber compounds in manufacturing, particularly for products like tires and it is considered a "green oil" due to its non-toxic, non-carcinogenic characteristics, serving as a safer alternative to traditional aromatic oils and it is from Panama Petrochem Ltd., India.
7. Tyre Pyrolysis Oil– It is a sustainable development goal material and it’s density is 0.91 g/cc. It is from Rathi industrial enterprises A9/ S-2, Sipcot Gummidipoondi, Tamilnadu, India.
8. 6PPD – It is an antioxidant to protect the rubber articles from oxidative degradation at room temperature as well as higher temperatures and it is from Nocil Ltd, Mumbai.
9. Stearic Acid –3F Industries Ltd, Nellore, Andhra Pradesh. It is used as a Process aid. Also, 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.
10. Struktol 40 MS – it is a homogenizing agent improves the homogeneity of elastomers of different polarity and viscosity, and it is from Lanxess India Private Limited., India.
11. Sulphur - Sulphur is the vulcanizing agent from Southern Minerals & Chemicals, Kerala
12. CBS- N-cyclohexyl-2-benzothiazolesulfenamide is a delayed action accelerator and it is from Nocil ltd, India.
13. Zinc Oxide –It acts as an activator for the rubber compound to activate the sulphur vulcanization and it is from POCL, Tamil Nadu.

Rubber Compound - Method of Preparation:
The method of a preparing a tyre innerliner rubber composition is done in Banbury Mixier with a tangential rotor and the temperature-controlled unit temperature is maintained between 15 Deg C to 25 Deg C and this water circulation is provided for chamber of Banbury Mixer.
Step 1: preparation of master batch
Mixing was done with the head temperature of the Banbury maintained between 65 and 80°C and the unloaded rotor speed maintained between 45 and 60 rpm. The mixing cycle was followed as:
a) The mixing chamber was charged with rubbers, homogenizing agent and allowed to mix for 0 to 35 seconds and further adding 50% of tyre pyrolysis oil and allowed it to mix for 20-40 seconds.
b) carbon black was added as a filler, 50% of remaining tyre pyrolysis oil, and rubber chemicals like antidegradant 6PPD, stearic acid, and they were allowed to mix for 100 to 270 seconds. c) Sweeping was done in the orifice and the mixture was allowed to mix for another 45 to 80 seconds. The rubber compound has been dumped at a temperature in the range of 135°C to 145°C and sheeted out in the laboratory two roll mill.
Step II Master Batch:
Step I master batch was added to the Lab Banbury Mixer and mixed for 80 to 150 seconds. The rubber compound has been dumped at a temperature of 110 to 120°C and sheeted out in the laboratory two roll mill.
Final Batch Preparation:
The mixing chamber was charged with the Step II master batch rubber compound and mixed for 5 to 30 seconds. The accelerator CBS, zinc oxide and vulcanization agent sulphur were added, and the mixture was mixed for 60 to 90 seconds. The rubber compound was dumped at a temperature in the range of 95°C to 115°C. The final batch has been sheeted out in the laboratory two roll mill.
The purpose of these tests is to measure the improved properties of the formulation related to the invention against control formulation. For this, NR: non extended SBR: IIR (50:45:5) tri blend based tyre innerliner rubber composition F1 & F2 reinforced by N326 carbon black 65 phr along with 26.9 phr & 21.9 phr of TDAE oil are prepared against NR: oil extended SBR: IIR triblend (50: 61.8: 5) based tyre innerliner rubber composition reinforced by carbon black grade N326 (C1) along with TDAE oil 15 phr is prepared and evaluated.
The present invention provides a tyre innerliner NR: non-oil extended SBR: IIR tri-blend (50:45:5) based rubber composition reinforced by N326 carbon black 65 phr along with 26.9 phr & 21.9 phr of TDAE oil (F1 & F2) gave t5 value is 21.30 minutes & 20.03 minutes which indicates the process safety when compared to NR: oil extended SBR: IIR triblend (50: 61.8: 5) tyre innerliner rubber composition C1 reinforced by 65 phr of N326 carbon black along with 15 phr (Control, C1) having t5 value 21.6 minutes. Note: t5 value greater than 15 minutes is good for processability.
The present invention provides a tyre innerliner NR: non-oil extended SBR: IIR tri-blend (50:45:5) based rubber composition reinforced by N326 carbon black 65 phr along with 26.9 phr & 21.9 phr of TDAE oil (F1 & F2) gave hardness value 51 Shore A & 56 Shore A against the NR: SBR: IIR triblend tyre innerliner rubber composition C1 reinforced by 65 phr of N326 carbon black (Control) along with 15 phr (Control, C1) having hardness 51 Shore A.
The present invention provides a tyre innerliner NR: non-oil extended SBR: IIR tri-blend (50:45:5) based rubber composition reinforced by N326 carbon black 65 phr along with 26.9 phr & 21.9 phr of TDAE oil (F1 & F2) gave Payne effect value is 0.45 Mpa & 0.61 Mpa which indicates the rubber filler interaction level is improved by 4.69% & 29.69% when compared to NR: oil extended SBR: IIR triblend (50: 61.8: 5) tyre inner liner rubber composition C1 reinforced by 65 phr of N326 carbon black along with 15 phr (Control, C1) having Payne effect value 0.65 Mpa.
The present invention provides a tyre innerliner NR: non-oil extended SBR: IIR tri-blend (50:45:5) based rubber composition reinforced by N326 carbon black 65 phr along with 26.9 phr & 21.9 phr of TDAE oil (F1 & F2) gave improved barrier properties by 13.60% & 17.97% when compared to NR: oil extended SBR: IIR triblend (50: 61.8: 5) tyre inner liner rubber composition C1 reinforced by 65 phr of N326 carbon black along with 15 phr (Control, C1).
The present invention provides a tyre innerliner NR: SBR: IIR tri-blend (50:45:5) based rubber composition reinforced by N326 carbon black 65 phr along with 26.9 phr & 21.9 phr of TDAE oil (F1 & F2) gave rebound resilience % values as 41.56 % and 42.76%.
Hence, NR: non-oil extended SBR: IIR tri blend-based tyre innerliner reinforced by N326 carbon black 65 phr along with TDAE oil provides excellent barrier properties i.e., lower oxygen transmission rate (lower air permeability), better rubber filler interaction along with processing properties when compared to NR: oil extended SBR: IIR triblend tyre innerliner rubber composition C1 reinforced by N326 carbon black (Control). The present invention provides tyre innerliner composition having Shore A ranges from 51 to 56 Shore A.
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 with 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. Payne Effect:
The Payne effect is an effective way of studying deagglomeration of fully reinforcing carbon black during the rubber compound mixing process. It should be an effective way of relating to carbon black aggregate—aggregate attraction vs. the carbon black aggregate attraction to the specific rubber hydrocarbon medium.
The Payne effect is the difference in storage modulus (G’) at relatively low elongation rates. The difference (G’@0.07% - G’ @ 10%) is caused by 'filler-filler interaction'. During mixing, the filler should be dispersed homogeneously through the compound, which indicates a break-up of agglomerates into primary particles, resulting in a filler network within the polymer network. Lower the difference (G’@0.07% - G’ @ 10%) value is lower the Payne effect which implies lower filler- filler interaction and better polymer -filler interaction.
The Payne Effect Strain (Test conditions: Sweep test, Strain Angle 0.07 to 300.00%, Temperature:70°C, Frequency: 1Hz is measured through Rubber Process Analyzer RPA 2000 premier from Alpha Technologies, USA in accordance with ASTM D 8059.
M3. Hardness of the rubber vulcanizate
Hardness of the Rubber Vulcanizate is measured in accordance with ASTM D 2240.
M4. Dynamic Mechanical Properties (Visco elastic properties of Rubber Vulcanizate)
Visco elastic properties of rubber vulcanizate are measured on a Rebound Resilience tester as per ASTM D 7121. ,CLAIMS:WE CLAIM
1. A tyre innerliner rubber composition comprising:
-natural rubber in an amount of 40–90 phr;
-styrene butadiene rubber in an amount of 5–60 phr;
-butyl rubber in an amount of 1–30 phr;
-carbon black in an amount of 1–85 phr;
-tyre pyrolysis oil in an amount of 1–50 phr;
-an anti-degradant in an amount of 0.1–4 phr;
-a vulcanization agent in an amount of 0.5–3 phr; and
-a primary accelerator in an amount of 0.5–3 phr,
wherein the tyre pyrolysis oil is obtained from the pyrolysis of waste tyres and acts as a process oil to enhance filler–polymer interaction and improve processability.

2. The tyre innerliner rubber composition as claimed in claim 1, wherein the anti-degradant is N-(1,3-dimethylbutyl)-N’-phenylenediamine (6PPD).

3. The tyre innerliner rubber composition as claimed in claim 1, wherein the vulcanization agent is sulphur.

4. The tyre innerliner rubber composition as claimed in claim 1, wherein the primary accelerator is N-cyclohexyl-2-benzothiazolesulfenamide (CBS).

5. The tyre innerliner rubber composition as claimed in claim 1, further comprising a homogenizing agent in an amount of 0.5–2 phr.

6. The tyre innerliner rubber composition as claimed in claim 1, wherein the pyrolysis oil has a density of about 0.91 g/cc and is derived from waste tyre feedstock.

7. The tyre innerliner rubber composition as claimed in claim 1, wherein the oxygen transmission rate is reduced relative to a control composition containing treated distillate aromatic extract (TDAE) oil.

8. The tyre innerliner rubber composition as claimed in claim 1, wherein the Payne effect value is lower than that of a control composition comprising oil-extended SBR, indicating improved filler dispersion and polymer–filler interaction.

9. A method of preparing a tyre innerliner rubber composition as claimed in claim 1, comprising:
(i) mixing rubbers with 50% of the tyre pyrolysis oil to obtain a first mixture;
(ii) adding carbon black, remaining tyre pyrolysis oil, and rubber chemicals including anti-degradant and activators;
(iii) dumping the mixture at a temperature of 135–145°C to obtain a master batch;
(iv) sheeting the master batch in a two-roll mill;
(v) Step I master batch was added to the Lab Banbury Mixer and mixed for 80 to 150 seconds. The rubber compound has been dumped at a temperature of 110 to 120°C and sheeted out in the laboratory two roll mill.
(vi) mixing the master batch with accelerators and vulcanization agents at a temperature of 95–115°C; and
(vii) sheeting the final mixture to obtain the tyre innerliner rubber composition.

10. The method as claimed in claim 9, wherein the master batch is prepared in a Banbury mixer at a head temperature between 65–80°C and a rotor speed between 45–60 rpm.