DESC:TECHNICAL FIELD OF INVENTION
The present invention relates to the field of rubber composition for tyre. More particularly, the present invention relates to a rubber composition using biocarbon black for the casing of the tyre and its method of preparation.

BACKGROUND OF INVENTION
The carcass of a tire, also known as the casing, is the fundamental structure of the tyre. Carcass act as the skeleton of a tyre. Generally, the reinforcement of tire carcass or casing rubber compounds is achieved by conventional ASTM (American Society for Testing and Materials) carbon blacks and inorganic fillers such as silica.
Further, in rubber composition a tackifier or resin is added to improve green tack of unvulcanized rubber compound and also to improve rubber to cord adhesion properties. The choice of resins that are conventionally available includes para- tertiary-butylphenol-acetylene resin, alkylphenol resin such as p-octylphenol- formaldehyde resin, aromatic hydrocarbon resin, aliphatic hydrocarbon resin,
petroleum resin, such as aliphatic cyclic hydrocarbon resin has been commonly used.
In developing a carcass/casing rubber compound for a tire, promoting rubber-to- fabric adhesion is essential for ensuring the structural integrity and performance of the tire. One effective approach to achieving this is by using surface treatment methods to create active surfaces on nanofillers.
WO2022097163 discloses a motorcycle tyre casing composition where the rubber composition has lower hysteresis and better adhesion properties. The rubber composition of tyre casing comprises natural or synthetic rubber or its blend, with reinforcing filler such as carbon black, and a naturally occurring Moringa oleifera
gum, containing the functional groups OH stretching, C-H stretching, C-O Stretching, C-C deformation and secondary OH. The invention is capable of providing 100 parts by weight of rubber composition, NR based rubber composition containing 5 phr Moringa oleifera gum containing rubber composition gave lower hysteresis with better adhesion properties of rubber compound with tyre cord. Also, it provides 100 parts by weight of rubber composition, NR based rubber composition containing 5 phr Moringa oleifera gum containing rubber composition gave higher tensile strength and 300 % modulus along with better ageing properties when compared to NR based rubber composition control compound, Fl containing 5 phr CI resin.
MXPA03000317 relates to a rubber composition having reduced hysteresis for use in a crown ply reinforcement of a tyre casing designed to bear heavy loads. The inventive rubber composition comprises an elastomer matrix containing natural rubber or a synthetic polyisoprene as major constituent, and a reinforcing filler containing carbon black, where the said carbon black simultaneously fulfils the
following conditions: (i) 45 <= CTAB specific surface in m2/g (as per the ASTM D3765-80 standard) <= 70; (ii) 45 <= BET specific surface in m2/g (as per the ASTM D4820-93 standard) <= 70; (iii) 45 <= iodine absorption index IA in mg/g (as per the ASTM D1510-81 standard) <= 70; (iv) BET surface/IA index ratio <= 1.07; (v) 115 <= DBP structure value in ml/100g (as per the ASTM D2414-93 standard) <= 170; (vi) 85 nm <= Stokes dst diameter in nm <= 145, wherein dst is the diameter of aggregates corresponding to the maximum frequency of Stokes diameters in an aggregate distribution; and (vii) D50/dst <= 0.0090. CTAB + 0.19, wherein D50 is the difference, in the aggregate distribution, between the Stoke diameters of the two aggregates corresponding to a common frequency equal to 50 of the maximum frequency of Stokes diameters, dst and D50 being measured by centrifugal photo-sedimentation analysis. The said patent application discusses the use of carbon black with specific properties to provide low hysteresis but does not provide any further implications to provide a composition that enables better fatigue to failure properties.
MXPA02011982 discloses a cross linkable or crosslinked rubber composition for use to produce a running tread of a tyre casing, and a tyre casing incorporating said running tread. The said rubber composition is based on: at least one or several diene elastomers, and a plasticizing agent including a glycerol oleic acid triester, and is such that said plasticizing agent comprises: in accordance with a mass fraction ranging between 45 % and 100 %, one or several compounds not extracted from petroleum, synthetic and/or natural, which include at least a glycerol fatty acid trimester, such that the assembly formed by the fatty acid(s) comprises oleic acid in a mass fraction not less than 60 %; and in a mass fraction ranging between 55 % and 0 %, one or several plasticizing oils derived from petroleum, of the paraffin, aromatic, naphthene type. The invention is particular applicable to tyre casings of the passenger vehicle type. The said patent application describes the use of oleic acid greater than 65% containing plasticizing oils in a tyre casing rubber composition. EP3174923 discloses a rubber mixture comprising a polymer base with a cross-linkable unsaturated chain, a reinforcing filler, a silane bonding agent, sulphur and vulcanizing agents. Part of the reinforcing filler consists of pyrolysis carbon black, whose surface is at least partially coated with a silica layer. The said patent discusses about the use of recovered carbon black and its partially coated with a silica layer along with silane bonding agent in tyre rubber composition to provide crack growth resistance.
WO2023077082 discloses a more environmentally friendly silica reinforced rubber composition comprising non-surface treated recovered carbon black. The rubber composition is particularly useful as tread rubber and have performance characteristics similar or improved to that of rubber compositions comprising conventional first-use carbon black produced using fossil fuel feedstock. The ability to get good, cured rubber composition performance using non- surface treated recovered carbon black facilitates the use of recovered carbon black for tire manufacturing. The said patent application describes the use of recovered carbon black in tyre tread rubber composition but fails to provide a bio carbon black-based tyre causing rubber composition.
DE112011101778 discloses a tire tread rubber composition includes diene rubber containing three kinds of rubber (E-SBR, modified S-SBR, and natural rubber (NR)) in a total amount of 80% by weight or more; and a filler in an amount of 100 to 140 parts by weight based on 100 parts by weight of the diene rubber, the filler containing 70% by weight or more of silica, wherein the diene rubber contains 10 to 25% by weight of the natural rubber, the weight ratio of the three kinds of rubber (E-SBR: modified S-SBR:NR) is 1 to 2:2.5 to 4:1, the styrene content of the E-SBR and the modified S-SBR is 35 to 40% by weight, and the difference between the glass transition temperature of the E-SBR and the glass transition temperature of the modified S-SBR is 10°C or lower. The said patent application describes diene rubber composition containing modified SSBR along with terpene resin to get better wet grip and abrasion resistance for a tyre tread but fails to use bio carbon black as a key component in tyre casing rubber composition and to find a solution for fatigue resistance.
The prior arts disclosed herein are directed towards modified diene rubber compositions, tread compositions in carbon black, use of plasticizing oils in tyre compositions, and are mostly related with aspects of low hysteresis, rolling resistance and traction. The rubber compositions that are conventionally available fail to provide a rubber composition for carcass with carbon black, capable of addressing the fatigue resistance of tires, since it is a critical factor affecting their lifespan and performance under various operating conditions.
Though carbon black is used to enhance the durability and strength of tire compounds, there remains a need to optimize its incorporation to further improve fatigue resistance. This present disclosure aims to investigate the use of bio carbon black in different concentrations and types of carbon black to improve rubber to cord adhesion properties. By systematically evaluating these factors, the disclosure provides a novel rubber composition which provides improved rubber to cord adhesion property along with better processability.

SUMMARY OF THE INVENTION
The present invention discloses a rubber composition for the casing of the tyre comprising: polymer matrix/Elastomeric matrix; reinforcing fillers carbon black; bio carbon black; activators; anti-degradants; dry bonding system; vulcanization agent; primary accelerator.
In some aspects of the present invention, the said rubber composition comprises: Natural Rubber (NR) ranges from 10-100 phr, styrene butadiene rubber (SBR) ranges from 1-70 phr, Polybutadiene Rubber ranges from 1-40 phr, Bio Carbon Black ranges from 1- 120 phr in particular 1-75 phr, Carbon Black ranges from 1-80 phr, silica ranges from 0-15 phr, zinc oxide ranges from 1-3.5 phr, stearic acid ranges from 1-3 phr, 6PPD ranges from 1-3 phr, MES oil or Low PCA oil ranges from 0-10 phr, dry bonding system ranges from 0-10 phr, resin ranges from 0-10 phr, CBS ranges from 1-3 phr, sulphur ranges from 1-3 phr.
In some aspects of the present invention, the resin may be selected from a group consisting of natural resin, phenolic resin, C5 resin or C5/C9 resin.
In some aspects of the rubber composition, use of bio carbon black in provides better adhesion properties of rubber compound that are bonded to reinforcing cord.
In some aspects of the present invention, 6PPD - N-(1,3-Dimethylbutyl)-N’-phenyl- p-phenylenediamine is an antioxidant for the said rubber composition.
In some aspects of the present invention Mild extracted solvate oil (MES Oil) or Low PCA Oil is an environmentally friendly process aid for the said rubber composition.
In some aspects of the present invention, CBS - N-cyclohexyl-2- benzothiazole sulfenamide is a delayed action sulfenamide accelerator for the said rubber composition.
In some aspects of the present invention, the method of preparing said rubber composition comprises the steps of:
mixing of polymer matrix for 10 to 40 seconds in a Banbury mixer at an unloaded rotor speed of at 50-65 rpm, head temperature at 55-65°C and ram pressure of 5 KP/cm2; adding of 100 % reinforcing filler carbon black and /or silica, bio carbon black, rubber chemical 6PPD, process aid MES oil or Low PCA oil, phenolic resin, resorcinol formaldehyde polymer resin (dry bonding system) and mixing for 60 to 230 seconds and sweeping down in the orifice and again mix for 30 to 120 seconds; dumping the compound at temperature range between 125- 145°C; and sheeting out rubber compound in two roll mill to provide a master batch; mixing the master batch compound with HMMM65 % Active (dry bonding system), vulcanizer and accelerator and for 60-180 seconds, in unloaded rotor speed of mixer in the range of 40-50 rpm, head temperature of Banbury mixer is of range of 55-65°C and ram pressure of 4 KP/cm2; dumping the final batch rubber compound at temperature range between 90 – 110°C; and sheet out the final batch rubber compound in two roll mill.
OBJECTS OF THE INVENTION:
The principal object of the present invention is to provide a rubber composition using biocarbon black for the carcass/casing component of the tyre.
Another object of the present invention is to provide a method of preparing rubber composition using biocarbon black for the carcass/casing component of the tyre.
Yet another object of the present invention is to provide rubber composition for tyre carcass/casing which provides better adhesion properties that are bonded to reinforcing cord.
Yet another object of the present invention is to provide high rubber elasticity which implies less heat generation.
Yet another object of the present invention to use bio carbon black as a renewable filler in place of carbon black reinforcing filler or partial replacement of reinforcing filler carbon black manufactured from fossil fuels.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Various embodiments of the disclosure are discussed in detail below. While specific implementations are discussed, it should be understood that this is done for illustration purposes only. A person skilled in the relevant art will recognize that other components and configurations may be used without parting from the spirit and scope of the disclosure. Numerous specific details are described to provide a thorough understanding of the disclosure. However, in certain instances, known details are not described in order to avoid obscuring the description.
References to one or an embodiment in the present disclosure can be references to the same embodiment or any embodiment; and such references mean at least one of the embodiments.
Reference to "one embodiment", "an embodiment", “one aspect”, “some aspects”, “an aspect” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the disclosure. The appearances of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Moreover, various features are described which may be exhibited by some embodiments and not by others.
The terms used in this specification generally have their ordinary meanings in the art, within the context of the disclosure, and in the specific context where each term is used. Alternative language and synonyms may be used for any one or more of the terms discussed herein, and no special significance should be placed upon whether or not a term is elaborated or discussed herein. In some cases, synonyms for certain terms are provided.
A recital of one or more synonyms does not exclude the use of other synonyms. The use of examples anywhere in this specification including examples of any terms discussed herein is illustrative only and is not intended to further limit the scope and meaning of the disclosure or of any example term. Likewise, the disclosure is not limited to various embodiments given in this specification. Without intent to limit the scope of the disclosure, examples of instruments, apparatus, methods and their related results according to the embodiments of the present disclosure are given below. Note that titles or subtitles may be used in the examples for convenience of a reader, which in no way should limit the scope of the disclosure. Unless otherwise defined, technical and scientific terms used herein have the meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. In the case of conflict, the present document, including definitions, will be controlled.
Additional features and advantages of the disclosure will be set forth in the description which follows, and in part will be obvious from the description, or can be learned by practice of the herein disclosed principles.
In an aspect of the present invention, a rubber composition using biocarbon black for the casing of the tyre is disclosed.
In some aspects of the present invention, composition for tyre casing, comprises polymer matrix; reinforcing fillers carbon black; bio carbon black; activators; anti- degradants; vulcanization agent; primary accelerators.
In some aspects of the present invention, the said rubber composition comprises Natural Rubber (NR) ranges from 10-100 phr.
In some aspects of the present invention, the said rubber composition comprises Styrene Butadiene Rubber (SBR) ranges from 1-70 phr.
In some aspects of the present invention, the said rubber composition comprises Polybutadiene Rubber ranges from 1-40 phr.
In some aspects of the present invention, the said rubber composition comprises Bio Carbon Black ranges from 1-120 phr. In some aspects of the present disclosure, the bio carbon black is manufactured using renewable resources like tree wood (biomass) having high calorific value 2400 Kcal/kg to 4500 Kcal/Kg, and particularly 4500 Kcal/Kg.
In some aspects of the present invention, the said rubber composition comprises Carbon Black ranges from 1-75 phr.
In some aspects of the present invention, the said rubber composition comprises silica ranges from 0-15 phr.
In some aspects of the present invention, the said rubber composition comprises zinc oxide ranges from 1-3.5 phr.
In some aspects of the present invention, the said rubber composition comprises stearic acid ranges from 1-3 phr.
In some aspects of the present invention, the said rubber composition comprises 6PPD ranges from 1-3 phr.
In some aspects of the present invention, the said rubber composition comprises MES oil or Low PCA oil ranges from 0-10 phr.
In some aspects of the present invention, the said rubber composition comprises dry bonding system that ranges from 0-10 phr.
In some aspects of the present invention, the said rubber composition comprises resin ranges from 0-10 phr.
In some aspects of the present invention, the resin may be selected from a group consisting of natural resin, C5 resin or C5/C9 resin.
In some aspects of the present invention, the said rubber composition comprises CBS ranges from 1-3 phr.
In some aspects of the present invention, the said rubber composition comprises sulphur ranges from 1-3 phr.
In some aspects of the rubber composition, bio carbon black provides better adhesion properties of rubber compound that are bonded to reinforcing cord.
In some aspects of the present invention, 6PPD - N-(1,3-Dimethylbutyl)-N’-phenyl-p-phenylenediamine is an antioxidant for the said rubber composition.
In some aspects of the present invention Mild extracted solvate oil (MES Oil) is an environmentally friendly process aid for the said rubber composition.
In some aspects of the present invention, CBS - N-cyclohexyl-2- benzothiazole sulfenamide is a delayed action sulfenamide accelerator for the said rubber composition.
In some aspects of the present invention, sulphur is the vulcanizer for the rubber composition.
In another aspect of the present invention, a method of preparing said rubber composition for tyre casing is provided.
In some aspects of the present invention, the method of preparing said rubber composition comprises the steps of:
mixing of polymer matrix for 10 to 40 seconds in a Banbury mixer at an unloaded rotor speed of 50-65 rpm, head temperature at 55-65°C and ram pressure of 5 KP/cm2;
adding of 100 % reinforcing filler carbon black, bio carbon black, silica, rubber chemical 6PPD, process aid MES oil, phenolic resin, dry bonding system resorcinol formaldehyde polymer resin and mixing for 60 to 230 seconds and sweeping down in the orifice and again mix for 30 to 120 seconds; dumping the compound at temperature range between 125- 145°C; and
Sheeting out rubber compound in two roll mills to provide a master batch;
mixing the master batch compound with dry bonding system HMMM65% Active, vulcanizer sulfur and accelerator CBS and for 60-180 seconds to provide a final batch, in unloaded rotor speed of mixer in the range of 40-50 rpm, head temperature of Banbury mixer is of range of 55-65°C and ram pressure of 4 KP/cm2; dumping the final batch rubber compound at temperature range between 90 – 110°C and sheet out the final batch rubber compound in two roll mill.
In some aspects of the present invention, characterization of unvulcanized and vulcanized rubber compound is provided.
Table 1: Rubber Composition in Phr
The below said table 1 shows an exemplary embodiment for the said rubber composition of the disclosure expressed in parts per hundred units of rubber (phr).
Ingredients Control formulation, F1 Formulation related to invention, F2 Formulation related to invention, F3
NR, ISNR 20 1 75.00 75.00 75.0
SBR 1502 2 10.00 10.00 10.0
PBR 1220 3 15.00 15.00 15.0
Bio Carbon Black 4 55.00 75.0
Carbon Black, N326 5 55.00
Precipitated Silica 6 5.00 5.00 5.00
Zinc oxide 3.50 3.50 3.50
Stearic acid 8 1.75 1.75 1.75
6PPD 9 1.00 1.00 1.0
MES Oil 10 3.00 3.00 3.0
Phenolic resin Tackifier 11 2.00 2.00 2.0
Resorcinol formaldehyde polymer resin 12 1.5 1.5 1.5
HMMM65% Active 13 1.00 1.00 1.0
CBS 14 1.50 1.50 1.5
Sulphur 15 2.00 2.00 2.0
1. NR – It is NR, ISNR 20 grade with ISNR 20 Indian Standard Natural Rubber ISNR 20 with the Mooney Viscosity, ML (1+4) @100°C is 76 MU from Mamparambil Rubber Industries, Kerala
2. SBR1502- It is emulsion polymerized styrene butadiene rubber with a bound styrene content in the range of 22.5 to 24.5 wt% and its Mooney viscosity ML (1+4) @ 100°C is in the range of 46.0-54.0 MU from Kumho Petrochemicals, Korea.
3. PBR1220– Polybutadiene rubber 1220 (Cisamer1220) is a solution polymerized high Cis - 1,4 Polybutadiene rubber (cis content – 96%) produced using complex stereospecific organometallic catalyst with a unmassed Mooney Viscosity - ML (1+4) @ 100°C is 45 MU from
4. Bio Carbon Black - Bio Carbon Black having the carbon weight percentage of the bio carbon black is greater than 75% as measured through SEM EDAX, the bio carbon black having an oil absorption number value ranging from 62 to 73 cc/100 gm and a specific surface area value ranging from 16 to 28 m²/gm from Engrow Carbon Energy Private Limited, Erode, Tamilnadu, India.
5. Carbon Black, N326 – It is High Abrasion Furnace low structure grade with an oil absorption no ranging from 67 to 77 cc/100 gm and the iodine surface area ranging from 77 to 87 mg/gm and its specific surface area ranging from 73 to 83 m2/gm from Himadri Carbon, West Bengal.
6. Precipitated Silica – its specific surface area ranging from 175 to 185 m2/gm from Tata Chemicals Limited, India from POCL, Tamil Nadu.
7. Zinc oxide inc oxide (ZnO) - Zinc oxide acts as a primary activator, while stearic acid improves its dispersion and solubility in the rubber, enhances the curing process, and contributes to the overall performance of the rubber compound from POCL India Limited, India.
8. Stearic acid – It is an activator in sulfur vulcanization systems, particularly in natural and synthetic rubbers.
9. 6PPD - N-(1,3-Dimethylbutyl)-N’-phenyl-p-phenylenediamine is an antioxidant from NOCL, India.
10. MES Oil or Low PCA oil– Mild extracted solvate oil or Low Polycyclic aromatics is an environmental friendly process aid from Low PCA oil from GP Petroleums limited, India.
11. Phenolic resin tackifier– It helps to improve the bonding between rubber and materials, such as steel cords or fabric in tyres, ensuring structural integrity. Further, it helps to increase tack, the property of uncured rubber to adhere to itself from Techno Wax Chem Pvt. Ltd., West Bengal.
12. Resorcinol formaldehyde polymer resin - RF resins is helpful in promoting strong adhesion between rubber compounds and reinforcing materials such as steel cords, polyester, and other fibers and to improve the structural integrity of tires, where the rubber compound needs to firmly bond with the reinforcing elements from Auropol India Pvt Ltd, West Bengal.
13. HMMM65% Active - HMMM 65 acts as a crosslinking agent, enhancing the strength and durability of the rubber. It also promotes adhesion between the rubber and materials like steel cords or fabric in tires. HMMM 65% Active is a key component in dry bonding systems for rubber-to-cord adhesion Rajsha Chemicals Pvt Ltd, Gujarat.
14. CBS - N-cyclohexyl-2- benzothiazole sulfenamide is a delayed action sulfenamide accelerator Nocil Limited, India.
15. Sulphur - It acts as a cross-linking agent /vulcanizing agent, forming cross-links (bridges) between the long rubber polymer chains from Southern Minerals & Chemicals, Kerala.
Method of preparation of rubber composition:
1. Preparation of master batch:
Mixing of masterbatch has been done in Banbury mixer by a thermomechanical process with an unloaded rotor speed of mixer is between range 50 and 65 rpm, head temperature of Banbury mixer is of range 55 and 65°C and ram pressure of 5 KP/cm2. Mixing of polymer matrix for 10 to 40 seconds; adding of 100 % reinforcing filler carbon black, bio carbon black, silica, rubber chemical 6PPD, phenolic resin tackifier, process aid MES oil, resin, dry bonding system and mixing for 60 to 230 seconds and sweeping down in the orifice and again mix for 30 to 120 seconds; dumping the compound at temperature range between 125- 145°C and sheeting out the master batch rubber compound in two roll mill.
2. Preparation of final batch:
Mixing of final batch has been done in Banbury mixer by a thermomechanical process with an unloaded rotor speed of mixer is between range 40 and 50 rpm, head temperature of Banbury mixer is of range 55 and 65°C and ram pressure of 4 KP/cm2.
Mixing the master batch compound with curatives i.e., Sulphur (vulcanizer) and CBS (accelerator) for 60 to 180 seconds and dumping the final batch rubber compound at temperature range between 90 – 110°C and sheet out the final batch rubber compound in two roll mill.
The furnace carbon black i.e., commercially available ASTM carbon black grades are manufactured using petroleum products/fossil fuels which are from non- renewable resources. The present invention aims to use bio carbon black (obtained from wood) produced from renewable resources and also the present invention aims to reduce/eliminate the use of carbon black produced from non-renewable resources.
The present invention thus provides a bio-carbon black-based composition for tire casing/carcass that significantly enhances rubber elasticity
The purpose of these tests is to measure the rubber compound properties of the compositions related to invention F2 & F3, against the control rubber composition F1. Three rubber compositions based on NR:SBR:BR formulation, reinforced by carbon black containing 55 phr to 75 phr of Bio carbon Black (F2 & F3) against F1 based formulation reinforced by carbon black containing 55 phr of reinforcing filler carbon black (F1) are prepared and evaluated.
The present invention provides 100 parts by weight of rubber composition F2 & F3, NR:SBR: PBR (75:10:15) blend-based rubber composition reinforced by 55 phr & 75 phr of renewable filler bio carbon black gave process safety, t5 value improved by 92.06% & 40.42% when compared NR: SBR: BR (75:10:15) blend-based rubber composition F1 (Control). T5 is greater than 15 minutes and is ideal value for casing rubber composition.
The present invention provides 100 parts by weight of rubber composition F2 & F3, NR:SBR: PBR (75:10:15) blend-based rubber composition reinforced by 55 phr & 75 phr of renewable filler bio carbon black provides H adhesion Big Value 7.17 Kgf & 6.83 Kgf when compared NR: SBR: BR (75:10:15) blend-based rubber composition F1 (Control) provides 7.06 Kgf. Ideal H adhesion Big value of Casing Rubber Composition is greater than 6.0 Kgf.
Also. The present invention provides 100 parts by weight of rubber composition F2 & F3, NR:SBR: PBR (75:10:15) blend-based rubber composition reinforced by 55 phr & 75 phr of renewable filler bio carbon black provides H adhesion Small Value 6.17 Kgf & 5.50 Kgf when compared NR: SBR: BR (75:10:15) blend-based rubber composition F1 (Control) provides 6.06 Kgf. Ideal H adhesion small value of Casing Rubber Composition is greater than 5.0 Kgf.
The present invention provides 100 parts by weight of rubber composition F2 & F3, NR:SBR: PBR (75:10:15) blend-based rubber composition reinforced by 55 phr & 75 phr of renewable filler bio carbon black provides 34.93% & 27.72% higher rubber elasticity when compared NR: SBR: BR (75:10:15) blend-based rubber composition F1 (Control).
Moreover, the present invention provides 100 parts by weight of rubber composition F2 & F3, NR:SBR: PBR (75:10:15) blend-based rubber composition reinforced by 55 phr & 75 phr of renewable filler bio carbon black provides 58 to 63 Shore A.
Hence, the present invention provides 100 parts by weight of rubber composition F2 & F3, NR:SBR: PBR (75:10:15) blend-based rubber composition reinforced by renewable filler bio carbon black provides better processability, rubber to cord adhesion properties and high rubber elasticity (less hysteresis) with the hardness of 58 to 63 Shore A.
Table 2: Characterization of Uncured Rubber Compound and Cured Rubber Vulcanizate
SL. No Properties F1,
Control formulation F2,
Formula related to invention F3, Formulation related to invention F2, Index F3, Index
1 Mooney Scorch time @ 125 Deg C
T5, min: min 16.75 32.17 23.52 192.06 140.42
2 H adhesion Test
Big, Kgf (Ideal value is greater than 6 Kgf) 7.06 7.17 6.83 - -
Small, Kgf
(Ideal value is greater than 5 Kgf) 6.06 6.17 5.50 - -
3 High Rubber Elasticity of Rubber Vulcanizate
Rebound Resilience at 23+/-2 Deg C, %
(Higher the index value is better) 53.25 71.85 68.01 134.93 127.72
4 Hardness of Rubber Vulcanizate
Hardness, Shore A 62 58 63 - -
In an exemplary scenario, characterization of unvulcanized and vulcanized rubber compound is provided:
Measurements and Tests include:
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. Rubber to Cord adhesion (H adhesion test)
Better adhesion properties of reinforcing cord that are bonded to rubber compound by H adhesion test procedure. The H adhesion test measurements are
carried out with a Universal Testing Machine Instron Make, Model No: 5966 in accordance with ASTM D4776. The tyre cord construction used for H Adhesion test is Nylon 6: N22 1260/2.
M3: High Rubber Elasticity of the Rubber Vulcanizate
Elasticity of the Rubber Vulcanizate is measured using Rebound Resilience tester as per ASTM D 7121
M4. Shore A Hardness of the Rubber Vulcanizate is assessed in accordance with ASTM D 2240.

Advantages:
1. Use of renewable filler Bio Carbon Black in tyre casing rubber composition.
2. Use of renewable filler Bio Carbon Black to replace reinforcing filler carbon black produced from fossil resources.
3. Use of renewable filler Bio Carbon Black to replace partially reinforcing carbon black filler produced from fossil resources.
4. Use of renewable filler Bio Carbon black can be used to replace or along with reinforcing filler carbon black.
5. Rubber composition containing renewable filler provides optimum rubber to cord adhesion properties, better processability along with high rubber elasticity characteristics.
,CLAIMS:WE CLAIM
1. A rubber composition for tyre casing, comprising:
Elastomer Matrix – 100 phr;
reinforcing fillers – 1 to 80 phr;
bio carbon black – 1 to 120 phr;
silica – 0 to 15 phr;
resin – 0 to 10 phr;
dry bonding system – 0 to 10 phr;
processing aid – 1 to 10 phr;
vulcanization activators – 2 to 10 phr;
anti-degradants – 1 to 2 phr;
vulcanization agent – 1 to 3.5 phr; and
primary accelerator – 1 to 3 phr;
wherein the bio carbon black is derived from renewable biomass sources, has a carbon content greater than 75% by weight, an oil absorption number ranging from 62 to 73 cc/100 gm, and a specific surface area of 16 to 28 m²/gm, and
wherein the dry bonding system comprises resorcinol formaldehyde resin and hexamethoxymethylmelamine (HMMM) with 65% activity.
2. The rubber composition for tyre casing as claimed in claim 1, wherein the rubbers are selected from natural rubber (NR), styrene-butadiene rubber (SBR), high-cis polybutadiene rubber (PBR), or combinations thereof.
3. The rubber composition for tyre casing as claimed in claim 1, wherein the reinforcing filler carbon black having
a nitrogen surface area of 73 to 83 m²/gm,
an iodine adsorption number of 77 to 87 mg/gm, and
an oil absorption number of 67 to 77 cc/100 gm.
4. The rubber composition for tyre casing as claimed in claim 1, wherein the silica has a specific surface area in the range of 175 to 185 m²/gm.
5. The rubber composition for tyre casing as claimed in claim 1, wherein the processing aid is selected from mild extracted solvate (MES) oil or low polycyclic aromatic (PCA) oil.
6. The rubber composition for tyre casing as claimed in claim 1, wherein the vulcanization activators are selected from zinc oxide and stearic acid in a weight ratio of 2 to 5 phr each.
7. The rubber composition for tyre casing as claimed in claim 1, wherein the anti-degradant is 6PPD – N-(1,3-Dimethylbutyl)-N'-phenyl-p-phenylenediamine.
8. The rubber composition for tyre casing as claimed in claim 1, wherein the resin is selected from phenolic resin, natural resin, C5 resin, or C5/C9 resin.
9. The rubber composition for tyre casing as claimed in claim 1, wherein the primary accelerator is CBS – N-cyclohexyl-2-benzothiazole sulphonamide.
10. The rubber composition for tyre casing as claimed in claim 1, wherein the vulcanization agent is sulphur.
11. A method for preparing a rubber composition for tyre casing as claimed in claim 1, comprising the steps of:
Master batch preparation:
mixing one or more rubbers in a Banbury mixer at a rotor speed of 50 to 65 rpm, temperature 55°C to 65°C, and ram pressure of 5 KP/cm² for 10 to 40 seconds;
adding bio carbon black, carbon black, silica, resin, processing aid, anti-degradants, and dry bonding system, followed by mixing for 60 to 230 seconds;
sweeping down in the orifice and mixing again for 30 to 120 seconds;
dumping the mixture at 125°C to 145°C to form a master batch;
sheeting out the master batch using a two-roll mill;
Final batch preparation:
mixing the master batch with vulcanization agent (sulphur) and primary accelerator (CBS) at rotor speed of 40 to 50 rpm, temperature 55°C to 65°C, and ram pressure of 4 KP/cm² for 60 to 180 seconds;
dumping the final batch at a temperature of 90°C to 110°C;
sheeting out the final rubber compound.
12. The method as claimed in claim 11, wherein the rubber vulcanizate exhibits:
Shore A hardness in the range of 58 to 63;
rebound resilience ranging from 68.01% to 71.85%;
Mooney scorch time (T5 at 125°C) greater than 15 minutes; and
H-adhesion big value greater than 6.0 kgf and small value greater than 5.0 kgf.