FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See section 10, rule 13)
/. Title of the invention: TREAD RUBBER COMPOSITION AND IMPLEMENTATIONS
THEREOF
2. Applicants)

NAME NATIONALITY ADDRESS
CEAT LIMITED Indian RPG HOUSE, 463, Dr. Annie Besant Road, Worli, Mumbai, Maharashtra 400030, India
3. Preamble to the description
COMPLETE SPECIFICATION
The following specification particularly describes the invention and the manner in which it
is to be performed.

FIELD OF INVENTION
[0001] The subject matter described herein relates to the field of rubber and in particular relates to a tread rubber, and more particularly a single tread rubber for automotive tires.
BACKGROUND OF THE INVENTION
[0002] Tires have become an important fragment in any vehicle as they largely contribute towards the vehicle performance. The performance of the tires with respect to their durability, wear resistance, rolling resistance will affect the fuel consumption of the vehicle. Hence a tire with an improved durability and performance is after sought in recent years so as to increase the economic value of the tire and thereby the vehicle. Moreover reduction in the usage of the fuel has been most critical element of research in the automobile industry for environment and economic reasons. Thus, there has been continuous researches in the development of tires via modification of the existing fragments of tires. Tire tread is a fundamental part of the tire and is the only in contact with the road or ground part. Tire tread gets worn off upon continuous usage and becomes major reason behind tire failure. A tire tread generally comprised of three portions, namely tread cap, tread base and the shoulder. Tread cap is responsible for gripping the road, providing directional stability, reducing rolling resistance and improving wear-and-tear resistance; the tread base reduces rolling resistance and damage to the casing; and the shoulder forms an optimal transition from the tread to the sidewall. Thus the tire tread is three sectioned part which serves the mentioned purposes. However the tire tread with cap and base, and in certain usage conditions would lead to tire failure due to tread shoulder separation. There have been various efforts in the past to bring about a working tire tread with improved performance as well eliminating the existing discomforts.
[0003] EP1818188A1 reveals a tire having a circumferential tread of a cap/base configuration composed of an outer tread rubber cap layer with a running surface of the tread and an underlying tread rubber base layer. JP4039895B2 discloses a method

for forming a tire tread constituent member and a pneumatic tire which involves plurality of unvulcanized rubber strip materials that are wound simultaneously by using injection molding technique.
[0004] Although a lot of attempts have been made to obtain a tread rubber of desired properties, there is still a need in the state of art for an automotive tire with tread rubber exhibiting improved tire performance as well as reducing complexity in tire manufacturing process.
SUMMARY OF THE INVENTION
[0005] In an aspect of the present disclosure, there is provided an automotive tire with improved endurance performance comprising a single tread rubber composition for cap and base, said tread rubber composition comprising: a) 75 to 85 phr of at least one natural rubber; b) 15 to 25 phr of at least one synthetic rubber; c) 35 to 45 phr of at least one carbon black as a reinforcing black filler and optionally about 4 to 8 phr of white filler silica; d) 1.0 to 2.0 phr of at least one crosslinking agent; and e) 1.0 to 2.0 phr of at least one accelerator, wherein the at least one carbon black has iodine surface area in the range of 120 to 160 g/kg; and the automotive tire has 5 to 15% increased endurance performance in accordance with IS15636.
[0006] In another aspect of the present disclosure, there is provided a method for preparation of the single tread rubber composition, the method comprising: a) mixing the at least one natural rubber, the at least one synthetic rubber, the at least one antioxidant, the at least one activator, the at least one processing aid, and the at least one coupling agent in banbury mixer to obtain a first mixture; b) blending the first mixture with the at least one crosslinking agent, the at least one accelerator, and the at least one retarder to obtain a second mixture; and c) discharging the second mixture from banbury mixer to obtain the composition.
[0007] 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.
DETAILED DESCRIPTION OF THE INVENTION
[0008] Those skilled in the art will be aware that the present disclosure is subject to
variations and modifications other than those specifically described. It is to be
understood that the present disclosure includes all such variations and modifications.
The disclosure also includes all such steps, features, compositions, and compounds
referred to or indicated in this specification, individually or collectively, and any and
all combinations of any or more of such steps or features.
Definitions
[0009] For convenience, before further description of the present disclosure, certain
terms employed in the specification, and examples are delineated here. These
definitions should be read in the light of the remainder of the disclosure and understood
as by a person of skill in the art. The terms used herein have the meanings recognized
and known to those of skill in the art, however, for convenience and completeness,
particular terms and their meanings are set forth below.
[0010] 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.
[0011] 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".
[0012] Throughout this specification, unless the context requires otherwise the word
"comprise", and variations such as "comprises" and "comprising", will be understood
to imply the inclusion of a stated element or step or group of element or steps but not
the exclusion of any other element or step or group of element or steps.
[0013] The term "including" is used to mean "including but not limited to".
"Including" and "including but not limited to" are used interchangeably.

[0014] Ratios, concentrations, amounts, and other numerical data may be presented
herein in a range format. It is to be understood that such range format is used merely
for convenience and brevity and should be interpreted flexibly to include not only the
numerical values explicitly recited as the limits of the range, but also to include all the
individual numerical values or sub-ranges encompassed within that range as if each
numerical value and sub-range is explicitly recited. For example, a weight in the range
of about 75 to 85 phr should be interpreted to include not only the explicitly recited
limits of about 75 phr to about 85 phr but also to include sub-ranges, such as 76 – 84
phr, 80-85 phr and so forth, as well as individual amounts, within the specified ranges,
such as 78 phr, 82 phr and 84 phr for example.
[0015] The term "at least one" is used to mean one or more and thus includes individual
components as well as mixtures/combinations.
[0016] For the purposes of the present disclosure, the term "phr" refers to parts per
hundred rubber, and it is a unit well used in the field of rubber technology to define the
amount of ingredients used.
[0017] For the purposes of the present disclosure, the term "kWh" refers to kilowatt
hour.
[0018] The term “crosslinking agent” refers to a substance that assist in the formation
of chemical links between molecular chains to form a three-dimensional network of
connected molecules. For example vulcanization/ hardening of rubber using sulphur is
an example of crosslinking. In the present disclosure the crosslinking agent is used to
bound the components of the rubber composition to form a rubber compound. The
crosslinking agent used in the present disclosure includes but not limited to sulphur,
insoluble sulphur.
[0019] The term “accelerator” refers to chemicals which are added to rubber
compounds to accelerate the rate of vulcanization. Rubber compounds without
accelerators take much longer time to cure. In the present disclosure, the accelerators
include but not limited to N-tert-butyl-2-benzothiazyl sulfonamide (TBBS), N-

cyclohexyl-2-benzothiazole sulfonamide (CBS), 2-(4-Morpholinothio)- benzothiazole (MBS).
[0020] The term “iodine surface area” refers to iodine absorption number which is a measure of the amount of iodine which can be adsorbed on the surface of a given mass of carbon black. The iodine adsorption number depends on the surface porosity and the various carbon black are characterized based on the iodine surface are or iodine absorption number. For instance, the carbon black of the present disclosure such as N-110, N-115, N-134, N-120, N-220 have iodine surface area in the range of 120 to 160 g/kg.
[0021] The term “antioxidant” refers to chemical which will offer protection from the
degradation of rubber and protect the rubber through the subsequent processing steps
and in storage. The rubbers can be slowly attacked by atmospheric ozone, leading to
degradation, and thus antioxidants provide a protection. In the present disclosure,
antioxidants include but not limited to N'-phenyl-p-phenylenediamine (6PPD), 2,2,4-
trimethyl-l,2-dihydroquinoline (TQ), N,N’-Bis(methylphenyl)-1,4-benzenediamine
(DP), 2,2,4-trimethyl-1,2-dihydroquinoline (TMQ), 1,2-dihydro-2,2,4-
trimethylquinoline (TMDQ), N-isopropyl-N’-phenyl-P-phenylenediamine (IPPD). [0022] The term “activator” refers to chemicals which are added to rubbers to activate curing. In the present disclosure activator includes but not limited to zinc oxide, stearic acid.
[0023] The term “processing aid” refers to chemicals added to rubber to facilitate handling of rubber for instance reduces stickiness. In the present disclosure, processing aid includes but not limited to wood rosin, wax.
[0024] The term “coupling agent” refers to a class of additives which can improve the property of the interface between rubbers and fillers and ensures homogenous mixing of the components. In the present disclosure, the coupling agent includes but not limited to polyethylene glycol, diethylene glycol is used to couple the filler i.e silica, carbon

black with rubber. The coupling agent can also be referred as silica process aid or silane coupling agent.
[0025] The term “retarder” refers to chemicals used to reduce the tendency of a rubber compound to vulcanize prematurely by increasing scorch delay (time from beginning of the heat cycle to the onset of vulcanization). Ideally, a retarder would have no effect on the rate of vulcanization. Retarders can also be as called a pre-vulcanization inhibitor (PVI). In the present disclosure retarders include but not limited to N-(cyclohexylthio) phthalimide (CTP), phthalic acid, salicylic acid.
[0026] The term “endurance performance” refers to the ability of the material the ability to withstand wear, pressure, or damage. In the present disclosure endurance performance refers to the durability of the tire even after continuous working. In the present disclosure, improved endurance performance of the automotive tire comprising the tread rubber composition is determined by endurance testing in accordance with IS15636. The improved endurance performance of the automotive tire is observed in comparison to the standard endurance in accordance with IS15636.
[0027] The term “ IS15636” refers to the standard endurance to be maintained by a tire and also defines a method of endurance testing of the tire. IS15636 method emphasizes that the outer diameter of the tire, measured 6 hours after the endurance test, shall not differ by more than ± 3.5 percent from the outer diameter as measured before the test. After undergoing the endurance test, the tire shall not exhibit any tread separation, ply separation, cord separation, chunking or broken cords. In the present disclosure, the automotive tire exhibits 5 to 15 % improved endurance performance when compared to the reference. In the present disclosure, EX5## is considered as the reference. This means that the automotive tire of the present disclosure is highly durable and is able to withstand wear and tear even after continuous long hours of running.
[0028] In the present disclosure, endurance performance index is measured which refers to the comparative endurance performance value. The lowering of endurance performances of the test tires and the reference tires are compared and is represented

as endurance resistance index. The endurance resistance of the reference tire is kept as 100 and the decrease or increase of the lowered endurance performance is reported. The higher the endurance performance index means the endurance performance have increased much more than the reference and the performance of the tire is better. And in the present disclosure, the endurance index is in the range of 100 to 110. [0029] The term “rolling resistance” refers to energy that the tire needs to maintain movement at a consistent speed over a surface. In other words, it is the effort required to keep a tire rolling. Lower the rolling resistance, lower will be the fuel consumption by the automotive/vehicle. In the present disclosure, rolling resistance index is measured which refers to the comparative rolling resistance value. The lowering of rolling resistances of the test tires and the reference tires are compared and is represented as rolling resistance index. The reference tire is kept as 100 and the decrease or increase of the lowered rolling resistance is reported. The higher the rolling resistance index means the rolling resistance have lowered much more than the reference and the performance of the tire is better. And in the present disclosure, the rolling resistance index is in the range of 105 to 120.
[0030] The term “ wear resistance” refers to the ability of the tire to withstand from damage after prolonged running. In the present disclosure, wear resistance index is measured which refers to the comparative rolling resistance value. The lowering of wear resistances of the test tires and the reference tires are compared and is represented as rolling resistance index. The reference tire is kept as 100 and the decrease or increase of the lowered wear resistance is reported. The higher the wear resistance index means the wear resistance have lowered much more than the reference and the performance of the tire is better. And in the present disclosure, the wear resistance index is in the range of 95 to 120.
[0031] The term “modulus 300%” refers to express the amount of stress in pounds per square inch (psi) required to stretch the test specimen i.e rubber to a given elongation. It expresses the resistance to extension or stiffness. modulus at 300%' is simply a stress

value for the material at an elongation of 300%. In the present disclosure, modulus
300% of the tread rubber composition has been measured.
[0032] The term “elongation at break” also known as fracture strain, is the ratio
between changed length and initial length after breakage of the test specimen i.e the
rubber. It expresses the capability of rubber compound to resist changes of shape
without crack formation. In the present disclosure, elongation at break of the tread
rubber composition is measured and reported.
[0033] The term “tensile strength” refers to the measurement of maximum stress
exerted on cured rubber compound to rupture and is expressed on pounds per square
inch (mega pascal). In the present disclosure, the tensile strength refers to the maximum
stress exerted on the cured tread rubber composition upto its rupture.
[0034] The term “hysteresis loss” refers to the difference between the amount of
energy absorbed when a rubber is stretched and the amount of energy released when
the rubber is relaxed. High hysteresis loss indicates a high loss of energy (and therefore
is not good for energy absorbing applications). Low hysteresis loss rubbers are more
resilient.
[0035] The term “abrasion or abrasion resistance” refers to the ability to withstand
surface loss of a material due to frictional forces. In the present disclosure, abrasion
refers to the property of the tread rubber composition to have minimum or no loss of
rubber mass in its surface due to friction.
[0036] The term “unaged tread rubber” refers to the as-prepared tread rubber and
“unaged physical properties” refer to the physical properties of the as prepared tread
rubber. On the other hand, “aged tread rubber” refers to the tread rubber that was
used/kept under certain conditions. In the present disclosure, the aged tread rubber was
subjected to a heat treatment of 80ºC for 7 days under normal air circulation. The term
“aged physical properties” refers to the physical properties measured for the aged tread
rubber.

[0037] The term “banbury mixer” refers to a machine with a pair of rotors with a specific shape and a relative rotation, which plasticizes and blends the polymer materials in a closed state with adjustable temperature and pressure and is primarily used in rubber mixing and plastic refining. In the present disclosure, the banbury mixer refers to the mixer machine used for preparing the tread rubber composition. [0038] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the disclosure, the preferred methods, and materials are now described. All publications mentioned herein are incorporated herein by reference.
[0039] 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.
[0040] In the view of the shortcomings of the existing literature, it can be understood that there is an increasingly dire need exists to develop a tread rubber composition for an automotive tire which can exhibit improved performance. Tread cap and tread base are the integral part of tire tread. Tread cap is used to get higher abrasion resistance there by providing higher mileage to the tire, whereas tread base is used for low heat build-up in shoulder region to prevent heat related failure called as tread shoulder separation. The present disclosure reveals a tread rubber composition which comprises only tread cap in place of tread cap and tread base. However the tread rubber composition of the present disclosure is designed in such a way that it can serve the purpose of tread base as well. The performance of the automotive tire with the tread rubber composition must be either unchanged or improved, which could be beneficial in the tire buildup. By eliminating tread base, all tread base related tire manufacturing processes becomes unessential and hence the tire manufacturing process will also be

made simpler. Accordingly the present disclosure reveals a single tread rubber composition for an automotive tire and a method of preparation of the tread rubber composition.
[0041] In an embodiment of the present disclosure, there is provided an automotive tire with improved endurance performance comprising a single tread rubber composition for cap and base, said tread rubber composition comprising: a) 75 to 85 phr of at least one natural rubber; b) 15 to 25 phr of at least one synthetic rubber; c) 35 to 45 phr of at least one carbon black; d)1.0 to 2.0 phr of at least one crosslinking agent; and 1.0 to 2.0 phr of at least one accelerator, wherein the at least one carbon black has iodine surface area in the range of 120 to 160 g/kg; and the automotive tire has 5 to 15% increased endurance performance in accordance with IS15636.
[0042] In an embodiment of the present disclosure, there is provided an automotive tire with improved endurance performance comprising a single tread rubber composition for cap and base, said tread rubber composition comprising: a) 77 to 84 phr of at least one natural rubber; b) 16 to 23 phr of at least one synthetic rubber; c) 38 to 45 phr of at least one carbon black; d) 1.2 to 1.8 phr of at least one crosslinking agent; and 1.1 to 1.8 phr of at least one accelerator, wherein the at least one carbon black has iodine surface area in the range of 120 to 160 g/kg; and the automotive tire has 5 to 15% increased endurance performance in accordance with IS15636. In another embodiment of the present disclosure, there is provided an automotive tire with improved endurance performance comprising a single tread rubber composition for cap and base, said tread rubber composition comprising: a) 78 to 83 phr of at least one natural rubber; b) 17 to 21 phr of at least one synthetic rubber; c) 40 to 45 phr of at least one carbon black; d) 1.4 to 1.7 phr of at least one crosslinking agent; and 1.1 to 1.6 phr of at least one accelerator, wherein the at least one carbon black has iodine surface area in the range of 120 to 160 g/kg; and the automotive tire has 5 to 15% increased endurance performance in accordance with IS15636.

[0043] In an embodiment of the present disclosure, there is provided an automotive tire with improved endurance performance comprising a single tread rubber composition for cap and base as disclosed herein, wherein the at least one natural rubber is selected from ribbed smoked sheet, polyisoprene rubber, or combinations thereof; the at least one synthetic rubber is selected from styrene butadiene rubber, butadiene rubber, or combinations thereof; the at least one carbon black is selected from a group consisting of N-110, N-115, N-134, N-120, N-220, N-330, N-375, and combinations thereof; the at least one crosslinking agent is selected from sulphur, insoluble sulphur, or combinations thereof; and the at least one accelerator is selected from N-tert-butyl-2-benzothiazyl sulfonamide (TBBS), N-cyclohexyl-2-benzothiazole sulfonamide (CBS), 2-(4-Morpholinothio)- benzothiazole (MBS), or combinations thereof.
[0044] In an embodiment of the present disclosure, there is provided an automotive tire with improved endurance performance comprising a single tread rubber composition for cap and base as disclosed herein, wherein the at least one natural rubber is selected from ribbed smoked sheet, polyisoprene rubber, or combinations thereof; the at least one synthetic rubber is selected from styrene butadiene rubber, butadiene rubber, or combinations thereof; the at least one carbon black is selected from a group consisting of N-134, N-220, N-330, N-375, and combinations thereof; the at least one crosslinking agent is selected from sulphur, insoluble sulphur, or combinations thereof; and the at least one accelerator is selected from N-tert-butyl-2-benzothiazyl sulfonamide (TBBS), N-cyclohexyl-2-benzothiazole sulfonamide (CBS), or combinations thereof. In another embodiment of the present disclosure, there is provided an automotive tire with improved endurance performance comprising a single tread rubber composition for cap and base as disclosed herein, wherein the at least one natural rubber is ribbed smoked sheet,; the at least one synthetic rubber is butadiene rubber; the at least one carbon black is selected from a group consisting of N-134, N-330, and combinations thereof; the at least one crosslinking agent is selected from

sulphur, insoluble sulphur, or combinations thereof; and the at least one accelerator is N-tert-butyl-2-benzothiazyl sulfonamide (TBBS).
[0045] In an embodiment of the present disclosure, there is provided an automotive tire with improved endurance performance comprising a single tread rubber composition for cap and base, said tread rubber composition comprising: a) 75 to 85 phr of at least one natural rubber selected from ribbed smoked sheet, polyisoprene rubber, or combinations thereof; b) 15 to 25 phr of at least one synthetic rubber selected from styrene butadiene rubber, butadiene rubber, or combinations thereof; c) 35 to 45 phr of at least one carbon black selected from a group consisting of N-110, N-115, N-134, N-120, N-220, N-330, N-375, and combinations thereof; d) 1.0 to 2.0 phr of at least one crosslinking agent selected from sulphur, insoluble sulphur, or combinations thereof; and 1.0 to 2.0 phr of at least one accelerator selected from N-tert-butyl-2-benzothiazyl sulfonamide (TBBS), N-cyclohexyl-2-benzothiazole sulfonamide (CBS), 2-(4-Morpholinothio)- benzothiazole (MBS), or combinations thereof, wherein the at least one carbon black has iodine surface area in the range of 120 to 160 g/kg; and the automotive tire has 5 to 15% increased endurance performance in accordance with IS15636.
[0046] In an embodiment of the present disclosure, there is provided an automotive tire with improved endurance performance comprising a single tread rubber composition for cap and base as disclosed herein, wherein the composition comprises (a) 2.5 to 4.0 phr of at least one antioxidant; (b) 1.0 to 6.5 phr of at least one activator; (c) 0.5 to 2.5 phr of at least one processing aid; (d) 0 to 5.0 phr of at least one coupling agent; and (e) 0.1 to 0.3 phr of at least one retarder.
[0047] In an embodiment of the present disclosure, there is provided an automotive tire with improved endurance performance comprising a single tread rubber composition for cap and base as disclosed herein, wherein the composition comprises (a) 2.8 to 3.8 phr of at least one antioxidant; (b) 2.0 to 6.2 phr of at least one activator; (c) 0.7 to 2.5 phr of at least one processing aid; (d) 0 to 4.8 phr of at least one coupling

agent; and (e) 0.12 to 0.28 phr of at least one retarder. In another embodiment of the present disclosure, there is provided an automotive tire with improved endurance performance comprising a single tread rubber composition for cap and base as disclosed herein, wherein the composition comprises (a) 2.9 to 3.5 phr of at least one antioxidant; (b)3.0 to 6.0 phr of at least one activator; (c) 1.0 to 2.5 phr of at least one processing aid; (d) 0 to 4.2 phr of at least one coupling agent; and (e) 0.14 to 0.25 phr of at least one retarder.
[0048] In an embodiment of the present disclosure, there is provided an automotive
tire with improved endurance performance comprising a single tread rubber
composition for cap and base as disclosed herein, wherein the at least one antioxidant
is selected from a group consisting of N'-phenyl-p-phenylenediamine (6PPD), 2,2,4-
trimethyl-l,2-dihydroquinoline (TQ), N,N’-Bis(methylphenyl)-1,4-benzenediamine
(DP), 2,2,4-trimethyl-1,2-dihydroquinoline (TMQ), 1,2-dihydro-2,2,4-
trimethylquinoline (TMDQ), N-isopropyl-N’-phenyl-P-phenylenediamine (IPPD), and combinations thereof; the at least one activator is selected from zinc oxide, active zinc oxide, nano zinc oxide, stearic acid, or combinations thereof; the at least one processing aid is selected from wood rosin, wax, or combinations thereof; the at least one coupling agent is selected from PEG (polyethylene glycol), DEG (diethylene glycol), or combinations thereof; and the at least one retarder is selected from a group consisting of N-(cyclohexylthio) phthalimide (CTP), phthalic acid, salicylic acid, and combinations thereof.
[0049] In an embodiment of the present disclosure, there is provided an automotive tire with improved endurance performance comprising a single tread rubber composition for cap and base as disclosed herein, wherein the at least one antioxidant is selected from a group consisting of N'-phenyl-p-phenylenediamine (6PPD), 2,2,4-trimethyl-l,2-dihydroquinoline (TQ), 2,2,4-trimethyl-1,2-dihydroquinoline (TMQ), and combinations thereof; the at least one activator is selected from zinc oxide, active zinc oxide, nano zinc oxide, stearic acid, or combinations thereof; the at least one

processing aid is selected from wood rosin, wax, or combinations thereof; the at least one coupling agent is selected from PEG (polyethylene glycol), DEG (diethylene glycol), or combinations thereof; and the at least one retarder is selected from a group consisting of N-(cyclohexylthio) phthalimide (CTP), phthalic acid, and combinations thereof.
[0050] In an embodiment of the present disclosure, there is provided an automotive tire with improved endurance performance comprising a single tread rubber composition for cap and base as disclosed herein, wherein the composition comprises (a) 2.5 to 4.0 phr of at least one antioxidant selected from a group consisting of N'-phenyl-p-phenylenediamine (6PPD), 2,2,4-trimethyl-l,2-dihydroquinoline (TQ), N,N’-Bis(methylphenyl)-1,4-benzenediamine (DP), 2,2,4-trimethyl-1,2-dihydroquinoline (TMQ), 1,2-dihydro-2,2,4-trimethylquinoline (TMDQ), N-isopropyl-N’-phenyl-P-phenylenediamine (IPPD), and combinations thereof; (b) 1.0 to 6.5 phr of at least one activator selected from zinc oxide, stearic acid, or combinations thereof; (c) 0.5 to 2.5 phr of at least one processing aid selected from wood rosin, wax, or combinations thereof; (d) 0 to 5.0 phr of at least one coupling agent selected from PEG (polyethylene glycol), DEG (diethylene glycol), or combinations thereof; and (e) 0.1 to 0.3 phr of at least one retarder selected from a group consisting of N-(cyclohexylthio) phthalimide (CTP), phthalic acid, salicylic acid, and combinations thereof.
[0051] In an embodiment of the present disclosure, there is provided an automotive tire with improved endurance performance comprising a single tread rubber composition for cap and base, said tread rubber composition comprising: a) 75 to 85 phr of at least one natural rubber; b) 15 to 25 phr of at least one synthetic rubber; c) 35 to 45 phr of at least one carbon black; d) 1.0 to 2.0 phr of at least one crosslinking agent; e)1.0 to 2.0 phr of at least one accelerator; f) 2.5 to 4.0 phr of at least one antioxidant; g) 1.0 to 6.5 phr of at least one activator; h) 0.5 to 2.5 phr of at least one processing aid; i) 0 to 5.0 phr of at least one coupling agent; and j) 0.1 to 0.3 phr of at least one retarder, wherein the at least one carbon black has iodine surface area in the

range of 120 to 160 g/kg; and the automotive tire has 5 to 15% increased endurance performance in accordance with IS15636.
[0052] In an embodiment of the present disclosure, there is provided an automotive tire with improved endurance performance comprising a single tread rubber composition for cap and base, said tread rubber composition comprising: a) 75 to 85 phr of at least one natural rubber selected from ribbed smoked sheet, polyisoprene rubber, or combinations thereof; b) 15 to 25 phr of at least one synthetic rubber selected from styrene butadiene rubber, butadiene rubber, or combinations thereof; c) 35 to 45 phr of at least one carbon black selected from a group consisting of N-110, N-115, N-134, N-120, N-220, N-330, N-375, and combinations thereof; d) 1.0 to 2.0 phr of at least one crosslinking agent selected from sulphur, insoluble sulphur, or combinations thereof; and 1.0 to 2.0 phr of at least one accelerator selected from N-tert-butyl-2-benzothiazyl sulfonamide (TBBS), N-cyclohexyl-2-benzothiazole sulfonamide (CBS), 2-(4-Morpholinothio)- benzothiazole (MBS), or combinations thereof; f) 2.5 to 4.0 phr of at least one antioxidant selected from a group consisting of N'-phenyl-p-phenylenediamine (6PPD), 2,2,4-trimethyl-l,2-dihydroquinoline (TQ), N,N’-Bis(methylphenyl)-1,4-benzenediamine (DP), 2,2,4-trimethyl-1,2-dihydroquinoline (TMQ), 1,2-dihydro-2,2,4-trimethylquinoline (TMDQ), N-isopropyl-N’-phenyl-P-phenylenediamine (IPPD), and combinations thereof; g) 1.0 to 6.5 phr of at least one activator selected from zinc oxide, stearic acid, or combinations thereof; h) 0.5 to 2.5 phr of at least one processing aid selected from wood rosin, wax, or combinations thereof; i) 0 to 5.0 phr of at least one coupling agent selected from PEG (polyethylene glycol), DEG (diethylene glycol), or combinations thereof; and j) 0.1 to 0.3 phr of at least one retarder selected from a group consisting of N-(cyclohexylthio) phthalimide (CTP), phthalic acid, salicylic acid, and combinations thereof, wherein the at least one carbon black has iodine surface area in the range of 120 to 160 g/kg; and the automotive tire has 5 to 15% increased endurance performance in accordance with IS15636.

[0053] In an embodiment of the present disclosure, there is provided an automotive tire with improved endurance performance comprising a single tread rubber composition for cap and base as disclosed herein, wherein the automotive tire has rolling resistance index in the range of 105 to 120; wear resistance index in the range of 95 to 120.
[0054] In an embodiment of the present disclosure, there is provided an automotive tire with improved endurance performance comprising a single tread rubber composition for cap and base, said tread rubber composition comprising: a) 75 to 85 phr of at least one natural rubber; b) 15 to 25 phr of at least one synthetic rubber; c) 35 to 45 phr of at least one carbon black; d) 1.0 to 2.0 phr of at least one crosslinking agent; and 1.0 to 2.0 phr of at least one accelerator, wherein the at least one carbon black has iodine surface area in the range of 120 to 160 g/kg; and the automotive tire has 5 to 15% increased endurance performance in accordance with IS15636 and the automotive tire has rolling resistance index in the range of 105 to 120; wear resistance index in the range of 95 to 120.
[0055] In an embodiment of the present disclosure, there is provided an automotive tire with improved endurance performance comprising a single tread rubber composition for cap and base, said tread rubber composition comprising: a) 75 to 85 phr of at least one natural rubber; b) 15 to 25 phr of at least one synthetic rubber; c) 35 to 45 phr of at least one carbon black; d) 1.0 to 2.0 phr of at least one crosslinking agent; e)1.0 to 2.0 phr of at least one accelerator; f) 2.5 to 4.0 phr of at least one antioxidant; g) 1.0 to 6.5 phr of at least one activator; h) 0.5 to 2.5 phr of at least one processing aid; i) 0 to 5.0 phr of at least one coupling agent; and j) 0.1 to 0.3 phr of at least one retarder, wherein the at least one carbon black has iodine surface area in the range of 120 to 160 g/kg; and the automotive tire has 5 to 15% increased endurance performance in accordance with IS15636 and the automotive tire has rolling resistance index in the range of 105 to 120; wear resistance index in the range of 95 to 120.

[0056] In an embodiment of the present disclosure, there is provided a method for preparation of the single tread rubber composition for automotive tire as disclosed herein, the method comprising: a) mixing the at least one natural rubber, the at least one synthetic rubber, the at least one antioxidant, the at least one activator, the at least one processing aid, and the at least one coupling agent in banbury mixer to obtain a first mixture; b) blending the first mixture with the at least one crosslinking agent, the at least one accelerator, and the at least one retarder to obtain a second mixture; and c) discharging the second mixture from banbury mixer to obtain the composition. [0057] In an embodiment of the present disclosure, there is provided a method for preparation of the single tread rubber composition for automotive tire comprising: : a) 75 to 85 phr of at least one natural rubber; b) 15 to 25 phr of at least one synthetic rubber; c) 35 to 45 phr of at least one carbon black; d) 1.0 to 2.0 phr of at least one crosslinking agent; e)1.0 to 2.0 phr of at least one accelerator; f) 2.5 to 4.0 phr of at least one antioxidant; g) 1.0 to 6.5 phr of at least one activator; h) 0.5 to 2.5 phr of at least one processing aid; i) 0 to 5.0 phr of at least one coupling agent; and j) 0.1 to 0.3 phr of at least one retarder, the method comprising: i) mixing the at least one natural rubber, the at least one synthetic rubber, the at least one antioxidant, the at least one activator, the at least one processing aid, and the at least one coupling agent in banbury mixer to obtain a first mixture; ii) blending the first mixture with the at least one crosslinking agent, the at least one accelerator, and the at least one retarder to obtain a second mixture; and iii) discharging the second mixture from banbury mixer to obtain the composition.
[0058] In an embodiment of the present disclosure, there is provided a method for preparation of the single tread rubber composition for automotive tire comprising: : a) 75 to 85 phr of at least one natural rubber; b) 15 to 25 phr of at least one synthetic rubber; c) 35 to 45 phr of at least one carbon black; d) 1.0 to 2.0 phr of at least one crosslinking agent; e)1.0 to 2.0 phr of at least one accelerator; f) 2.5 to 4.0 phr of at least one antioxidant; g) 1.0 to 6.5 phr of at least one activator; h) 0.5 to 2.5 phr of at

least one processing aid; i) 0 to 5.0 phr of at least one coupling agent; and j) 0.1 to 0.3 phr of at least one retarder, the method comprising: i) mixing the at least one natural rubber, the at least one synthetic rubber, the at least one antioxidant, the at least one activator, the at least one processing aid, and the at least one coupling agent in banbury mixer to obtain a first mixture; ii) blending the first mixture with the at least one crosslinking agent, the at least one accelerator, and the at least one retarder to obtain a second mixture; and iii) discharging the second mixture from banbury mixer to obtain the composition and wherein the automotive tire has 5 to 15% increased endurance performance in accordance with IS15636; rolling resistance index in the range of 105 to 120; and wear resistance index in the range of 95 to 120.
[0059] In an embodiment of the present disclosure, there is provided a method for preparation of the single tread rubber composition for automotive tire as disclosed herein, wherein the mixing is carried out at a temperature in the range of 150-165˚C at a time in the range of 2-4 minutes and at a discharge energy in the range of 15-25 kWh. [0060] In an embodiment of the present disclosure, there is provided a method for preparation of the single tread rubber composition for automotive tire as disclosed herein, wherein the blending is carried out at a temperature in the range of 95-115ºC at a time in the range of 2-3 minutes and at a discharge energy in the range of 8-10 kWh. [0061] In an embodiment of the present disclosure, there is provided a method for preparation of the single tread rubber composition for automotive tire as disclosed herein, wherein the composition is extruded in single screw extruder at a temperature in the range of 110-125ºC.
[0062] In an embodiment of the present disclosure, there is provided a method for preparation of the single tread rubber composition for automotive tire as disclosed herein, the method comprising: a) mixing the at least one natural rubber, the at least one synthetic rubber, the at least one antioxidant, the at least one activator, the at least one processing aid, and the at least one coupling agent in banbury mixer at a temperature in the range of 150-165˚C at a time in the range of 2-4 minutes and at a

discharge energy in the range of 15-25 kWh to obtain a first mixture; b) blending the first mixture with the at least one crosslinking agent, the at least one accelerator, and the at least one retarder to obtain a second mixture; and c) discharging the second mixture from banbury mixer to obtain the composition.
[0063] In an embodiment of the present disclosure, there is provided a method for preparation of the single tread rubber composition for automotive tire as disclosed herein, the method comprising: a) mixing the at least one natural rubber, the at least one synthetic rubber, the at least one antioxidant, the at least one activator, the at least one processing aid, and the at least one coupling agent in banbury mixer to obtain a first mixture; b) blending the first mixture with the at least one crosslinking agent, the at least one accelerator, and the at least one retarder at a temperature in the range of 95-115ºC at a time in the range of 2-3 minutes and at a discharge energy in the range of 8-10 kWh to obtain a second mixture; and c) discharging the second mixture from banbury mixer to obtain the composition.
[0064] In an embodiment of the present disclosure, there is provided a method for preparation of the single tread rubber composition for automotive tire as disclosed herein, the method comprising: a) mixing the at least one natural rubber, the at least one synthetic rubber, the at least one antioxidant, the at least one activator, the at least one processing aid, and the at least one coupling agent in banbury mixer to obtain a first mixture; b) blending the first mixture with the at least one crosslinking agent, the at least one accelerator, and the at least one retarder to obtain a second mixture; and c) discharging the second mixture from banbury mixer to obtain the composition and wherein the composition is extruded in single screw extruder at a temperature in the range of 110-125ºC.
[0065] In an embodiment of the present disclosure, there is provided a method for preparation of the single tread rubber composition for automotive tire as disclosed herein, the method comprising: a) mixing the at least one natural rubber, the at least one synthetic rubber, the at least one antioxidant, the at least one activator, the at least

one processing aid, and the at least one coupling agent in banbury mixer at a temperature in the range of 150-165˚C at a time in the range of 2-4 minutes and at a discharge energy in the range of 15-25 kWh to obtain a first mixture; b) blending the first mixture with the at least one crosslinking agent, the at least one accelerator, and the at least one retarder at a temperature in the range of 95-115ºC at a time in the range of 2-3 minutes and at a discharge energy in the range of 8-10 kWh to obtain a second mixture; and c) discharging the second mixture from banbury mixer to obtain the composition and wherein the composition is extruded in single screw extruder at a temperature in the range of 110-125ºC.
[0066] In an embodiment of the present disclosure, there is provided a method for preparation of the single tread rubber composition for automotive tire as disclosed herein, the method comprising: a) mixing the at least one natural rubber, the at least one synthetic rubber, the at least one antioxidant, the at least one activator, the at least one processing aid, and the at least one coupling agent in banbury mixer to obtain a first mixture; b) blending the first mixture with the at least one crosslinking agent, the at least one accelerator, and the at least one retarder to obtain a second mixture; and c) discharging the second mixture from banbury mixer to obtain the composition and wherein the composition is extruded in single screw extruder at a temperature in the range of 110-125ºC.
[0067] In an embodiment of the present disclosure, there is provided a method for preparation of the single tread rubber composition for automotive tire as disclosed herein, the method comprising: a) mixing the at least one natural rubber, the at least one synthetic rubber, the at least one antioxidant, the at least one activator, the at least one processing aid, and the at least one coupling agent in banbury mixer to obtain a first mixture; b) blending the first mixture with the at least one crosslinking agent, the at least one accelerator, and the at least one retarder to obtain a second mixture; and c) discharging the second mixture from banbury mixer to obtain the composition and

wherein the composition is cured at a temperature in the range of 145 to 155ºC for a time period in the range of 30 to 34 minutes.
[0068] In an embodiment of the present disclosure, there is provided a method for preparation of the single tread rubber composition for automotive tire as disclosed herein, the method comprising: a) mixing the at least one natural rubber, the at least one synthetic rubber, the at least one antioxidant, the at least one activator, the at least one processing aid, and the at least one coupling agent in banbury mixer to obtain a first mixture; b) blending the first mixture with the at least one crosslinking agent, the at least one accelerator, and the at least one retarder to obtain a second mixture; and c) discharging the second mixture from banbury mixer to obtain the composition and wherein the composition is in the form of sheets.
[0069] In an embodiment of the present disclosure, there is provided a method for preparation of the single tread rubber composition for automotive tire as disclosed herein, the method comprising: a) mixing the at least one natural rubber, the at least one synthetic rubber, the at least one antioxidant, the at least one activator, the at least one processing aid, and the at least one coupling agent in banbury mixer to obtain a first mixture; b) blending the first mixture with the at least one crosslinking agent, the at least one accelerator, and the at least one retarder to obtain a second mixture; and c) discharging the second mixture from banbury mixer to obtain the composition [0070] Although the subject matter has been described with reference to specific embodiments, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as alternate embodiments of the subject matter, will become apparent to persons skilled in the art upon reference to the description of the subject matter. It is therefore contemplated that such modifications can be made without departing from the spirit or scope of the present subject matter as defined.

EXAMPLES
[0071] The disclosure will now be illustrated with the working examples, which is intended to illustrate the working of disclosure and not intended to take restrictively to imply any limitations on the scope of the present disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one ordinary person skilled in the art to which this disclosure belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice of the disclosed methods and compositions, the exemplary methods, devices and materials are described herein. It is to be understood that this disclosure is not limited to particular methods, and experimental conditions described, as such methods and conditions may apply.
[0072] The forthcoming examples explains that how the present disclosure provides an automotive tire with single tread rubber composition for tread cap and tread base. The tread rubber composition comprises natural rubber, synthetic rubber, crosslinking agent, accelerator and carbon black in the specified weight ranges (phr). The tread rubber composition also includes the coupling agent, activators, antioxidants, processing aids and a retarder in the mentioned phr. The performance of the automotive tire from the tread rubber composition has been measured and compared with the reference. The present disclosure provides a tread rubber composition for an automotive tire with improved endurance performance, better rolling resistance and wear resistance indices. The physical properties of the unaged and aged tread rubber composition are also determined to understand the change in the properties of the tread rubber composition with respect to aging. The present disclosure also provides a method for preparing the tread rubber composition. Overall, an automotive tire with tread rubber composition which can be cap rubber and replaces a combination of cap and base rubber, yet serving the functions of both cap and base has been disclosed in the present disclosure. Additionally, the present disclosure reveals a lesser complex tire

manufacturing process by providing a single tread rubber in place of tread cap and tread rubber.
EXAMPLE 1
MATERIALS REQUIRED
[0073] For the purpose of the present disclosure, following raw materials with the
specified grades/brands were used for obtaining the single tread rubber composition
for an automotive tire.
a) Ribbed smoked sheet (RSS4) the standard sheet rubber - RPD Cochin India;
b) Butadiene rubber (BR) -Cisamer PBR 01 from Reliance Industries Mumbai;
c) Carbon black grades N134, N-220, N-330, N-375, N-660 - from PCBL, India;
d) Zinc oxide of W.S. Luxmi brand from JG chemicals pvt. Ltd;
e) Stearic acid i.e stearic acid lubstric 995 from Godrej Industries Ltd;
f) 6PPD i.e. Vulkanox 4020 from Lanxess India Pvt Ltd;
g) Wood rosin R2 from Dujodwala resins and terpins; h) Ra Wax 0207 from Raj Petro Specialities Pvt. Ltd;
i) Pilnox TDQ (TMQ) from National Organic Chemical Ind. Ltd;
j) Accinox 100 (DP) from PMC Rubber Chemicals India P.Ltd;
k) MFIL 200G (Silica) from Madhu Silica;
l) Volcosulf 18 (Sulphur) from Solar Chemferts Pvt. Ltd;
m) Crystex HD OT 20 (Insoluble Sulphur)from Flexsys Chemicals;
n) Vulkacit NZ/EG-C (TBBS) from Lanxess India Pvt Ltd; and
o) Accitard RE (CTP) from PMC Rubber Chemicals India P.Ltd [0074] Rolling resistance test was carried out in rolling resistance machine & RRC coefficient (N/kN) was measured based on ISO28580, torque Method. Endurance test of tire was carried out based on the standard IS15636, run up to failure and hours of run till failure was recorded. Tensile strength and Elongation at break was carried out using Toyoseiki strograph AE-CT. Dynamic stiffness and Hysteresis loss was obtained using Eplexor 500N and abrasion was obtained from Ueshima lambourn AB-102.

Single tread rubber composition of the present disclosure
[0075] The tread rubber composition of the present disclosure comprised various
components such as the natural rubber and synthetic rubber, along with carbon black
of specific grades as filler, a crosslinking agent and an accelerator. The composition
also comprised of antioxidants, coupling agent, processing aid, activator and retarder.
In the present disclosure, the components and their phr ranges were varied to obtain a
single tread rubber composition which can serve as both cap and base. Various tread
rubber compositions were prepared and their properties were analysed to obtain the
single tread rubber with improved performance.
[0076] Table 1 depicts the various tread rubber composition prepared and compared
against the reference cap and reference base rubber composition.

Category Component/
Composition (phr) EX1* EX2# EX3# EX4* EX5## EX6**
Natural rubber RSS-4 75.00 82.00 80.00 55.00 55.00 100.00
Synthetic rubber BR 25.00 18.00 20.00 45.00 45.00
Activator Zinc oxide 4.00 3.50 3.50 4.00 2.50 5.00

Stearic acid 3.00 2.00 2.00 3.00 2.50 2.00
Processing aid Wood rosin 1.00 1.00

Wax 1.00 1.50 1.50 1.00 2.50 1.00

Processing oil 10.00 9.00 14.00 10.00
Antioxidants 6PPD 2.50 2.00 2.00 2.25 2.25 1.50

TMQ 0.50 0.50 1.00 1.00

DP 0.50 0.50
Carbon black (Filler) N-220 50.00 58.00

N-330 20.00

N-375 50.00

N-134 42.00 25.00

N-660 45.00
Silica (White filler) 8.00 4.00 8.00 4.00
Coupling agent Silica Process aid 1.00
Crosslinking agent Sulphur 1.60 0.70 0.70 1.70 1.60 1.50

Insoluble Sulphur (20% Oil) 0.90 0.90
Accelerator TBBS 0.96 1.25 1.25 0.95 0.90 0.9
Retarder CTP 0.15 0.15 0.15 0.25 0.25 0.15
* represents tread rubber having cap and base compound;
# represents tread rubber having only cap compound and no base compound of the
present disclosure;
## represents tread cap compound and no base compound from the known art considered as reference cap compound; and
** represents only base compound.
[0077] Table 1 shows various components taken in the mentioned proportion for the
preparation of the tread rubber composition for automotive tires. For example, EX1*
represents the tread rubber composition having both cap and base compound comprised
75 phr of RSS4 (natural rubber), 25 phr of BR (synthetic rubber), 50 phr of N-375
carbon black, 1.6 phr of sulphur (crosslinking agent) and 0.96 phr of TBBS
(accelerator). The tread rubber composition comprised other components such as
activator, antioxidants, coupling agent, processing aid and retarder as per the table 1
respectively. Similarly other tread rubber composition EX2#, EX3#, EX4*, EX5## and
EX6** were prepared from various components in their measured phr as depicted in
Table 1. EX1* and EX4*are the tread rubber composition with a combination of both
tread cap and tread base compound. EX2# and EX3# are the tread rubber composition
with only cap compound. EX5## is the cap rubber composition and is considered as
reference cap compound. And EX6** is the base rubber compound. For the purpose of

mixing the components to prepare the tread rubber composition, banbury mixer and sheeted out two-roll mill were utilized.
Method of preparation of tread rubber composition of the present disclosure [0078] The method of preparation tread rubber composition of the present disclosure is explained below. EX2# was prepared by mixing 82 phr of RSS4, 18 phr of BR, 3.00phr of antioxidants i.e. 2.00 phr of 6PPD, 0.50 phr of TNQ, 0.50 phr of DP, 5.50 phr of activators (zinc oxide – 3.50 phr and stearic acid – 2.00 phr) with 2.00 combined phr of wood rosin and wax and then 4.00 phr of silica in the banbury mixer at a temperature in the range of 150-165˚C for a time period of 2-4 minutes with a discharge energy in the range of 15-25 kWh and the first mixture was obtained. This first mixture was then blended with 0.70 of Sulphur, 0.90 of insoluble Sulphur, 1.25 phr of TBBS and 0.15 of CTP at a temperature in the range of 95-115ºC for a time period of 2-3 minutes with a discharge energy in the range of 8-10 kWh to result in a second mixture. The second mixture was discharged from the banbury mixer to produce tread rubber composition and was further extruded into sheets. The extruded sheets were then kept undisturbed for minimum of 4 hours before preparing automotive tires.
[0079] Curing of the tread rubber composition was carried out at a temperature of 148ºC for a time period of 32 minutes and was subjected to compression molding with 2 piece molds to obtain the automotive tires. Automotive tires i.e LCV tires of varying sizes were molded out from the tread rubber composition prepared above. [0080] The automotive tire from tread rubber composition prepared above was subjected to various analysis on their physical and mechanical properties for understanding the effect of different tread rubber composition on the performance of the tires.
EXAMPLE 2
Measurement of properties and Results
[0081] Tires from the tread rubber composition of Example 1 were subjected to testing
the properties such as endurance, rolling resistance and wear resistance. Further the

physical properties such as tensile strength, modulus 300%, elongation at break, hysteresis loss and abrasion of the unaged and aged tread rubber were determined. All the measurements have been represented as index i.e. as a comparative value against the reference. In the present disclosure, the reference considered is the EX5## which is the reference cap compound. All the parameters for EX5## is kept as 100 and the change (increase/decrease) in the parameters with respect to EX5## is determined and denoted for the other examples.
[0082] Tire endurance of the tire was based on the standard IS15636 to determine the no of hours of continuous run of the tire until failure. Endurance measurements of the tires were determined and the endurance index was obtained by comparing the endurance values with the reference cap compound (EX5##). Rolling resistance was carried out on the tire in the rolling resistance machine of tube type bias truck tire. 3 samples were tested for repeatability testing and the average value is reported. Rolling resistance coefficient was obtained for each tire. Rolling resistance index was determined by comparing the obtained value against the reference cap compound (EX5##). Similarly wear resistance index has been reported in comparison to the reference cap compound. Furthermore all the physical properties were also measured and indexed based on the reference cap compound (EX5##).
[0083] Table 2 provides the rolling resistance, endurance and wear resistance indices of the tires from the tread rubber composition of the present disclosure.

Index rating EX1* EX2# EX3# EX4* EX5##
Tire Endurance index 105 100 110 105 100
Tire rolling resistance 105 110 115 100 100
Tire Wear resistance 100 115 100 105 100

[0084] From Table 2, it can be observed that the tires EX2# and EX3# with single tread rubber having only the cap composition exhibit improved performance when compared to the tires EX1* and EX4* having both cap and base compound. Endurance index and the rolling resistance index of EX3# were found to be the greatest of all the tread rubber compositions of the present disclosure. Also EX2# has highest wear resistance index and rolling resistance index when compared to the reference cap compound. Thus EX2# and EX3# are considered working examples which comprised only the cap compound. And the EX1* and EX4* were not desired, as their performance were not highly favourable when compared to EX2# and EX3#. Hence automotive tires having the tread rubber composition adhering to the components with respective phr of the present disclosure were found to perform better than the existing (reference) and the other tread rubber compositions. This proved that a single tread rubber composition with only cap compound would suffice the purpose of both cap and base rubber compound, thereby eliminating the use of base compound from the tread rubber composition. [0085] Furthermore the physical properties of the tread rubber composition were analysed and is reported herein. Table 3 represents the unaged physical properties of the tread rubber composition. Table 4 depicts the aged physical properties of the tread rubber composition and the tread rubber composition was aged at 80ºC for 7 days under normal air circulation. Table 3 – Unaged physical properties

EX1* EX2# EX3# EX4* EX5## EX6**
Modulus @ 300% 151 144 153 110 100 103
Tensile strength 106 132 118 103 100 94
Elongation at Break 84 93 89 97 100 89

Dynamic Stiffness 109 125 100 108 100 74
Hysteresis loss 123 131 140 111 100 162
Abrasion 109 124 105 107 100 45
Table 4 Aged physical properties at 80ºC for 7 days

EX1* EX2# EX3# EX4* EX5## EX6**
Modulus @ 300% 138 140 142 110 100 99
Tensile strength 97 116 112 101 100 87
Elongation at Break 77 89 86 93 100 89
[0086] Results from Table 3 and 4 detailed the unaged and aged physical properties of the tread rubber composition. EX2# and EX4# displayed surprising results with enhanced physical properties in the unaged as well aged rubber composition. Whereas the tread rubber composition having both cap and base composition EX1* and EX4* had decreased elongation at break in its aged and unaged properties and the other measurements were lower compared to EX2# and EX3#. Thus these results further demonstrated that the EX2# and EX3# falling within the scope of the tread rubber composition of the present disclosure performed better than the other tread rubber composition.
[0087] The tread rubber composition of the present disclosure had components and their corresponding weights in accordance to serving as both cap and base but used only cap compound. This was achieved by maintaining the various weights for various components for example, EX2# had reduced phr of carbon black when compared to the reference cap compound EX5##. The reduction of the carbon black would eventually help in maintaining the abrasion resistance, thereby improving the rolling and wear

resistance of the tire. And additionally, EX2# and EX3# have increased natural rubber when compared to EX5## which could linked to lowering the hysteresis loss and in turn improving the strength of the tread rubber composition. Further, the components such as silica, processing oil were reduced or totally eliminated which resulted in positive impact on lowering of the heat build up of the tire and supplementing to the wear resistance of the tire. Above all, the tread rubber composition functioning as both cap and base reduced the complexity in the tire manufacturing process. And moreover, single tread rubber in place of tread cap and tread rubber eliminated the major tire failure due to cap-base separation.
[0088] The examples proved that the automotive tire with tread rubber composition within the specified ranges as exemplified above had increased endurance performance, improved rolling resistance and wear resistance indices. Also the physical properties of the unaged and aged rubber composition were intact to increase the performance of the tire comprising the same. Any deviation in the tread rubber composition with respect to its components and weight (phr) resulted in tread rubber with unsought performance. The tread rubber composition includes only the cap compound however exhibits the functions of both cap and base. The tread rubber composition of the present disclosure eliminates the inclusion of base compound which simplified the tire manufacturing process as well as improved the tire performance. Further, the present disclosure also provides a method for preparing the tread rubber composition for the automotive tires.
Advantages of the present disclosure
[0089] The present disclosure discloses an automotive tire comprising single tread rubber composition in place of tread cap and tread base with improved endurance performance. The present disclosure reveals an automotive tire with tread rubber composition having 5 to 15% increased endurance performance in accordance with IS15636. The automotive tire of the present disclosure exhibits improved rolling resistance index in the range of 105 to 120 and wear resistance index in the range of 95

to 120. The improved rolling resistance and wear resistance lead to lower consumption of fuel and increased life of the tire, thereby increasing the economic viability of the tire. The tread rubber composition of the present disclosure has components and their weights in such a way that hysteresis loss is lowered and the strength of compound increases. Further the heat build-up during the long usage of the tire with the tread rubber composition is lowered and improves the overall performance of the tire. The present disclosure eliminates the use of base compound and provides a single tread rubber which eventually results in the lesser complexity in the tire manufacturing process. The base compound elimination is also advantageous as it avoids tire failure occurring due to tread should separation. The present disclosure also provides a convenient method of preparation of the tread rubber composition.

I/We Claim:
1. An automotive tire with improved endurance performance comprising a single
tread rubber composition for cap and base, said tread rubber composition
comprising:
a. 75 to 85 phr of at least one natural rubber;
b. 15 to 25 phr of at least one synthetic rubber;
c. 35 to 45 phr of at least one carbon black;
d. 1.0 to 2.0 phr of at least one crosslinking agent; and
e. 1.0 to 2.0 phr of at least one accelerator,
wherein the at least one carbon black has iodine surface area in the range of 120 to 160 g/kg; and
the automotive tire has 5 to 15% increased endurance performance in accordance with IS15636.
2. The automotive tire as claimed in claim 1, wherein the at least one natural rubber is selected from ribbed smoked sheet, polyisoprene rubber, or combinations thereof; the at least one synthetic rubber is selected from styrene butadiene rubber, butadiene rubber, or combinations thereof; the at least one carbon black is selected from a group consisting of N-110, N-115, N-134, N-120, N-220, N-330, N-375, and combinations thereof; the at least one crosslinking agent is selected from sulphur, insoluble sulphur, or combinations thereof; and the at least one accelerator is selected from N-tert-butyl-2-benzothiazyl sulfonamide (TBBS), N-cyclohexyl-2-benzothiazole sulfonamide (CBS), 2-(4-Morpholinothio)- benzothiazole (MBS), or combinations thereof.
3. The automotive tire as claimed in claim 1, wherein the composition comprises (a) 2.5 to 4.0 phr of at least one antioxidant; (b) 1.0 to 6.5 phr of at least one activator; (c) 0.5 to 2.5 phr of at least one processing aid; (d) 0 to 5.0 phr of at least one coupling agent; and (e) 0.1 to 0.3 phr of at least one retarder.

4. The automotive tire as claimed in claim 3, wherein the at least one antioxidant is selected from a group consisting of N'-phenyl-p-phenylenediamine (6PPD), 2,2,4-trimethyl-l,2-dihydroquinoline (TQ), N,N’-Bis(methylphenyl)-1,4-benzenediamine (DP), 2,2,4-trimethyl-1,2-dihydroquinoline (TMQ), 1,2-dihydro-2,2,4-trimethylquinoline (TMDQ), N-isopropyl-N’-phenyl-P-phenylenediamine (IPPD), and combinations thereof; the at least one activator is selected from zinc oxide, stearic acid, or combinations thereof; the at least one processing aid is selected from wood rosin, wax, or combinations thereof; the at least one coupling agent is selected from PEG (polyethylene glycol), DEG (diethylene glycol), or combinations thereof; and the at least one retarder is selected from a group consisting of N-(cyclohexylthio) phthalimide (CTP), phthalic acid, salicylic acid, and combinations thereof.
5. The automotive tire as claimed in claims 1 to 4, wherein the automotive tire has rolling resistance index in the range of 105 to 120; wear resistance index in the range of 95 to 120.
6. A method for preparation of the single tread rubber composition as claimed in claims 1 to 5, the method comprising:
a. mixing the at least one natural rubber, the at least one synthetic rubber,
the at least one antioxidant, the at least one activator, the at least one
processing aid, and the at least one coupling agent in banbury mixer to
obtain a first mixture;
b. blending the first mixture with the at least one crosslinking agent, the
at least one accelerator, and the at least one retarder to obtain a second
mixture; and
c. discharging the second mixture from banbury mixer to obtain the
composition.
7. The method as claimed in claim 6, wherein the mixing is carried out at a
temperature in the range of 150-165˚C at a time in the range of 2-4 minutes.

8. The method as claimed in claim 6, wherein the blending is carried out at a temperature in the range of 95-115ºC at a time in the range of 2-3 minutes.
9. The method as claimed in claim 6, wherein the composition is extruded in single screw extruder at a temperature in the range of 110-125ºC.