FORM 2
THE PATENTS ACT, 1970 (39 of 1970) & THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See section 10, rule 13)
1. Title of the invention: COMPOSITION OF TRUCK AND BUS RADIAL TIRE BELT
COMPOUND
2. Applicant(s)

NAME NATIONALITY ADDRESS
CEAT LIMITED Indian RPG HOUSE, 463, Dr. Annie Besant Road, Worli, Mumbai, Maharashtra 400 030, India
3. Preamble to the description
COMPLETE SPECIFICATION
The following specification particularly describes the invention and the manner in which it
is to be performed.

FIELD OF INVENTION
[001] The subject matter described herein relates to the field of radial tires and in particular relates to a composition of truck and bus radial tire belt compound, and a process for preparing thereof.
BACKGROUND OF THE INVENTION
[002] Tire selection is one of the most important factors for tire life. Choosing the correct tire specification significantly improves tire life and reduces vehicle operational costs. There are various types of tires including radial, bias and solid tires which all offer specific benefits, that helps them to find their application in the field of automobiles, machinery or the like. These tires serve different purposes, but radial tires are advantageous over the bias tires in many ways. These radial tires are mainly used in trucks and buses. Truck and bus radial tires utilize a series of steel cords extending from the beads and across the tread, so that the cords are laid at approximately right angle to the centre line of the tread, and parallel to each other, as well as utilizes belts situated directly beneath the tread. This network of cords gives the tire strength and shape. Due to the all-steel radial construction, the sidewall of a radial tire is more flexible as compared to a bias tire, thereby, resulting in a shorter, but wider footprint. Belt plies are two or more strong layers of cord just under the tread area of the tire. The primary function of belt plies is to provide strength and stability to the tire tread. They play an important role in improving tire mileage, impact resistance, and traction. It is evident that the belt compound is an integral part of the radial tire belt package. Belt compound is used as a coating on the steel belts during tire manufacturing and which holds the steel belt structure in place after the tire is cured and in the finished product. [003] There has been a constant effort in obtaining a rubber composition of belt to provide the best working radial tires. JP2007313944A discloses a three-layered belt layer constituted by a metal cord surface coating layer using an insulation method, a belt crossing layer central part and a crossing layer end. KR100269997B1 discloses a

tire having belt rubber composition which comprised a lower alkyl acrylate or lower alkyl methacrylate, a graft copolymer and a diene.
[004] Although a lot of attempts have been made to modify the belt compound in radial tires, there is still a need in the state of the art to obtain a truck bus radial tire belt compound with improved traction and ageing properties.
SUMMARY OF THE INVENTION
[005] In an aspect of the present disclosure, there is provided a composition for Truck and Bus Radial tire (TBR) belt compound comprising: (a) 50-100 phr of at least one natural rubber; (b) 10-50 phr of at least one synthetic rubber; (c) 60-70 phr of at least one carbon black; and (d) 7-9 phr of at least one cross-linking agent.
[006] In another aspect of the present disclosure, there is provided a process for preparing a composition for truck and bus radial tire (TBR) belt compound comprising: (a) 50-100 phr of at least one natural rubber; (b) 10-50 phr of at least one synthetic rubber; (c) 60-70 phr of at least one carbon black; and (d) 7-9 phr of at least one cross-linking agent, said process comprising: (a) obtaining at least one natural rubber; (b) obtaining at least one synthetic rubber; (c) obtaining at least one carbon black; (d) obtaining at least one cross-linking agent; and (e) contacting the at least one natural rubber, the at least one synthetic rubber; the at least one carbon black; and the at least one cross-linking agent to obtain the composition.
[007] In yet another aspect of the present disclosure, there is provided a tire comprising the composition for truck and bus radial tire (TBR) belt compound, said composition comprising: (a) 50-100 phr of at least one natural rubber; (b) 10-50 phr of at least one synthetic rubber; (c) 60-70 phr of at least one carbon black; and (d) 7-9 phr of at least one cross-linking agent.
[008] 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
[009] 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
[0010] 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.
[0011] 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.
[0012] 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".
[0013] 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.

[0014] The term "including" is used to mean "including but not limited to". "Including" and "including but not limited to" are used interchangeably.
[0015] 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 concentration in the range of about 50-100 phr should be interpreted to include not only the explicitly recited limits of about 50 phr to about 100 phr but also to include sub-ranges, such as 51-99 phr, 55-90 phr and so forth, as well as individual amounts, including fractional amounts, within the specified ranges, such as 52.95 phr, and 90.24 phr for example. [0016] The term "at least one" is used to mean one or more and thus includes individual components as well as mixtures/combinations.
[0017] 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.
[0018] As disclosed herein, the term “dynamic creep index” of the compound refers to the measure of time-dependent deformation resulting from stress applied on the compound and the term “belt endurance index” of the tire refers to the extent to which a tire is able to withstand wear and tear due to continuous load and mechanical stress. [0019] 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.

[0020] 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.
[0021] The current belt compound of radial tires has a higher dynamic creep value. The higher dynamic creep value of a tire leads to a lower endurance in the belt endurance test. When the vehicles such as bus and truck having this conventional belt compound (with high creep and low endurance) are used for carrying heavy loads at higher or lower speeds, their tires are subjected to a significant amount of stress. The significant amount of stresses in the form of separation of the tread and outer steel belt from the tire casing and inner steel belt leads to a catastrophic radial tire failure. Hence, it is important that the composition of belt compounds should be prepared in such a way that they withhold all the stresses and damages thereof so that the tires can have a prolonged life.
[0022] In the view of the shortcomings of the existing literature, it can be understood that there is a need in the state of art for belt compound of a truck and bus radial tire that not only exhibits improved properties but also enhances the performance of the tire used in various road applications. The present disclosure provides one such composition of truck and bus radial tire which addresses the problems of the belt compound available in the market. The present disclosure provides a composition of truck and bus radial tire belt compound comprising: 50-100 phr of at least one natural rubber; 10-50 phr of at least one synthetic rubber; 60-70 phr of at least one carbon black; and 7-9 phr of at least one cross-linking agent. The composition for the belt compound exhibits lowered dynamic creep and increased belt endurance. Additionally, the usage of adding Volatile Organic Compounds (VOC) in the composition is also eliminated so as to lower the dynamic creep value. With this, the present disclosure helps to increase the tenacity and life of the tires and improves the rolling resistance of truck and bus radial tire.

[0023] In an embodiment of the present disclosure, there is provided a composition for truck and bus radial tire (TBR) belt compound comprising: (a) 50-100 phr of at least one natural rubber; (b) 10-50 phr of at least one synthetic rubber; (c) 60-70 phr of at least one carbon black; and (d) 7-9 phr of at least one cross-linking agent. [0024] In an embodiment of the present disclosure, there is provided a composition for truck and bus radial tire (TBR) belt compound comprising: (a) 60-90 phr of at least one natural rubber; (b) 10-30 phr of at least one synthetic rubber; (c) 62-70 phr of at least one carbon black; and (d) 7-9 phr of at least one cross-linking agent. In another embodiment of the present disclosure there is provided a composition comprising: (a) 65-85 phr of at least one natural rubber; (b) 10-20 phr of at least one synthetic rubber; (c) 65-68 phr of at least one carbon black; (d) 7.5-8.5 phr of at least one cross-linking agent.
[0025] In an embodiment of the present disclosure, there is provided a composition for truck and bus radial tire (TBR) belt compound comprising: (a) 50-100 phr of at least one natural rubber; (b) 10-50 phr of at least one synthetic rubber; (c) 60-70 phr of at least one carbon black; and (d) 7-9 phr of at least one cross-linking agent, wherein the at least one natural rubber is selected from the group consisting of Ribbed Smoked Sheet RSS1, RSS2, RSS3, RSS4, and combinations thereof. In another embodiment of the present disclosure, the at least one natural rubber is RSS3.
[0026] In an embodiment of the present disclosure, there is provided a composition for truck and bus radial tire (TBR) belt compound comprising: (a) 50-100 phr of at least one natural rubber; (b) 10-50 phr of at least one synthetic rubber; (c) 60-70 phr of at least one carbon black; and (d) 7-9 phr of at least one cross-linking agent, wherein the at least one synthetic rubber is polyisoprene rubber.
[0027] In an embodiment of the present disclosure, there is provided a composition for truck and bus radial tire (TBR) belt compound comprising: (a) 50-100 phr of at least one natural rubber; (b) 10-50 phr of at least one synthetic rubber; (c) 60-70 phr of at least one carbon black; and (d) 7-9 phr of at least one cross-linking agent, wherein the

at least one carbon black is selected from the group consisting of carbon black N326, carbon black N358, and combinations thereof. In another embodiment of the present disclosure, the at least one carbon black is N326. In yet another embodiment of the present disclosure, the at least one carbon black is N358.
[0028] In an embodiment of the present disclosure, there is provided a composition for truck and bus radial tire (TBR) belt compound comprising: (a) 50-100 phr of at least one natural rubber; (b) 10-50 phr of at least one synthetic rubber; (c) 60-70 phr of at least one carbon black; and (d) 7-9 phr of at least one cross-linking agent, wherein the at least one cross-linking agent is selected from the group consisting of sulfur, insoluble sulfur and combinations thereof. In another embodiment of the present disclosure, the at least one cross-linking agent is insoluble sulfur, wherein the insoluble sulfur is selected from the group consisting of 10% oil-treated insoluble sulfur, 20% oil-treated insoluble sulfur, 33% oil-treated insoluble sulfur, and combinations thereof. [0029] In an embodiment of the present disclosure, there is provided a composition for truck and bus radial tire (TBR) belt compound comprising: (a) 50-100 phr of at least one natural rubber; (b) 10-50 phr of at least one synthetic rubber; (c) 60-70 phr of at least one carbon black; and (d) 7-9 phr of at least one cross-linking agent, wherein the at least one natural rubber is selected from the group consisting of Ribbed Smoked Sheet (RSS1), RSS2, RSS3, RSS4, and combinations thereof and wherein the at least one synthetic rubber is polyisoprene rubber and wherein the at least one carbon black is selected from the group consisting of carbon black N326, carbon black N358, and combinations thereof and wherein the at least one cross-linking agent is selected from the group consisting of sulfur, insoluble sulfur, and combinations thereof. [0030] In an embodiment of the present disclosure, there is provided a composition for truck and bus radial tire (TBR) belt compound comprising: (a) 50-100 phr of at least one natural rubber; (b) 10-50 phr of at least one synthetic rubber; (c) 60-70 phr of at least one carbon black; (d) 7-9 phr of at least one cross-linking agent; and (e) at least one additive selected from the group consisting of at least one adhesion promoter, at

least one activator, at least one antioxidant, at least one rubber accelerator, and combinations thereof.
[0031] In an embodiment of the present disclosure, there is provided a composition for truck and bus radial tire (TBR) belt compound comprising: (a) 50-100 phr of at least one natural rubber; (b) 10-50 phr of at least one synthetic rubber; (c) 60-70 phr of at least one carbon black; (d) 7-9 phr of at least one cross-linking agent; and (e) at least one additive selected from the group consisting of at least one adhesion promoter, at least one activator, at least one antioxidant, at least one rubber accelerator, and combinations thereof, wherein the at least one adhesion promoter is selected from the group consisting of cobalt boro acylate, cobalt borate alkanoate and combinations thereof having a concentration in the range of 0.5-1 phr; the at least one activator is selected from the group consisting of zinc oxide, active zinc oxide, nano zinc oxide and combinations thereof having a concentration in the range of 8-10 phr; the at least one antioxidant is selected from the group consisting of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylendiamine (6PPD), 2,2,4-trimethyl-l,2-dihydroquinoline (TQ), and combinations thereof having a concentration in the range of 1.0-2.0 phr, and the at least one rubber accelerator is N,N'-Dicyclohexyl-2-benzothiazole sulfonamide (DCBS), having a concentration in the range of 0.8-1.5 phr.
[0032] In an embodiment of the present disclosure, there is provided a composition for truck and bus radial tire (TBR) belt compound comprising: (a) 50-100 phr of at least one natural rubber; (b) 10-50 phr of at least one synthetic rubber; (c) 60-70 phr of at least one carbon black; (d) 7-9 phr of at least one cross-linking agent; (e) 0.5-1.0 phr of at least one adhesion promoter; (f) 8-10 phr of at least one activator; (g) 1.0-2.0 phr of at least one antioxidant and (h) 0.8-1.5 phr of at least one rubber accelerator. [0033] In an embodiment of the present disclosure, there is provided a composition for truck and bus radial tire (TBR) belt compound comprising: (a) 50-100 phr of at least one natural rubber; (b) 10-50 phr of at least one synthetic rubber; (c) 60-70 phr of at least one carbon black; (d) 7-9 phr of at least one cross-linking agent; and (e) at least

one additive selected from the group consisting of at least one adhesion promoter, at
least one activator, at least one antioxidant, at least one rubber accelerator, and
combinations thereof, wherein the at least one natural rubber is selected from the group
consisting of RSS1, RSS2, RSS3, RSS4 and combinations thereof and wherein the at
least one synthetic rubber is polyisoprene rubber and wherein the at least one carbon
black is selected from the group consisting of Carbon black N326, Carbon black N358,
and combinations thereof and wherein the at least one cross-linking agent is selected
from the group consisting of sulfur, insoluble sulfur and combinations thereof and
wherein the at least one adhesion promoter is selected from the group consisting of
cobalt boro acylate, cobalt borate alkanoate and combinations thereof and wherein the
at least one activator is selected from the group consisting of zinc oxide, active zinc
oxide, nano zinc oxide and combinations thereof and wherein the at least one
antioxidant is selected from the group consisting of N-(1,3-dimethylbutyl)-N'-phenyl-
p-phenylendiamine (6PPD), 2,2,4-trimethyl-l,2-dihydroquinoline (TQ), and
combinations thereof and wherein the at least one rubber accelerator is N,N'-
Dicyclohexyl-2-benzothiazole sulfonamide (DCBS).
[0034] In an embodiment of the present disclosure, there is provided a composition for truck and bus radial tire (TBR) belt compound comprising: (a) 50-100 phr of at least one natural rubber; (b) 10-50 phr of at least one synthetic rubber; (c) 60-70 phr of at least one carbon black; and (d) 7-9 phr of at least one cross-linking agent, wherein the composition has a dynamic creep index in the range of 55-65. In another embodiment of the present disclosure, the composition has a dynamic creep index is 56-59. [0035] In an embodiment of the present disclosure there is provided a composition for truck and bus radial tire (TBR) belt compound comprising: (a) 50-100 phr of at least one natural rubber; (b) 10-50 phr of at least one synthetic rubber; (c) 60-70 phr of at least one carbon black; and (d) 7-9 phr of at least one cross-linking agent, wherein the composition has a belt endurance index in the range of 110-115. In another

embodiment of the present disclosure, the composition has a belt endurance index in the range of 112-113.
[0036] In an embodiment of the present disclosure there is provided a composition for truck and bus radial tire (TBR) belt compound comprising: (a) 50-100 phr of at least one natural rubber; (b) 10-50 phr of at least one synthetic rubber; (c)b60-70 phr of at least one carbon black; and (d) 7-9 phr of at least one cross-linking agent, wherein the composition has a dynamic creep index in the range of 55-65 and wherein the composition has a belt endurance index in the range of 110-115.
[0037] In an embodiment of the present disclosure, there is provided a composition for truck and bus radial tire (TBR) belt compound comprising: (a) 50-100 phr of at least one natural rubber; (b) 10-50 phr of at least one synthetic rubber; (c) 60-70 phr of at least one carbon black; (d) 7-9 phr of at least one cross-linking agent; and (e) at least one additive selected from the group consisting of at least one adhesion promoter, at least one activator, at least one antioxidant, at least one rubber accelerator, wherein the composition has a dynamic creep index in the range of 55-65.
[0038] In an embodiment of the present disclosure, there is provided a composition for truck and bus radial tire (TBR) belt compound comprising: (a) 50-100 phr of at least one natural rubber; (b) 10-50 phr of at least one synthetic rubber; (c) 60-70 phr of at least one carbon black; (d) 7-9 phr of at least one cross-linking agent; and (e) at least one additive selected from the group consisting of at least one adhesion promoter, at least one activator, at least one antioxidant, at least one rubber accelerator, wherein the composition has a belt endurance index in the range of 110-115.
[0039] In an embodiment of the present disclosure, there is provided a composition for truck and bus radial tire (TBR) belt compound comprising: (a) 50-100 phr of at least one natural rubber; (b) 10-50 phr of at least one synthetic rubber; (c) 60-70 phr of at least one carbon black; (d) 7-9 phr of at least one cross-linking agent; and (e) at least one additive selected from the group consisting of at least one adhesion promoter, at least one activator, at least one antioxidant, at least one rubber accelerator, and

combinations thereof, wherein the at least one natural rubber is selected from the group
consisting of RSS1, RSS2, RSS3, RSS4, and combinations thereof and wherein the at
least one synthetic rubber is polyisoprene rubber and wherein the at least one carbon
black is selected from the group consisting of carbon black N326, carbon black N358,
and combinations thereof and wherein the at least one cross-linking agent is selected
from the group consisting of sulfur, insoluble sulfur and combinations thereof and
wherein the at least one adhesion promoter is selected from the group consisting of
cobalt boro acylate, cobalt borate alkanoate and combinations thereof and wherein the
at least one activator is selected from the group consisting of zinc oxide, active zinc
oxide, nano zinc oxide and combinations thereof and wherein the at least one
antioxidant is selected from the group consisting of N-(1,3-dimethylbutyl)-N'-phenyl-
p-phenylendiamine (6PPD), 2,2,4-trimethyl-l,2-dihydroquinoline (TQ), and
combinations thereof and wherein the at least one rubber accelerator is N,N'-
Dicyclohexyl-2-benzothiazole sulfonamide (DCBS), wherein the composition has a
dynamic creep index in the range of 55-65 and wherein the composition has a belt
endurance index in the range of 110-115.
[0040] In an embodiment of the present disclosure there is provided a process for preparing a composition for truck and bus radial tire (TBR) belt compound comprising (a) 50-100 phr of at least one natural rubber; (b) 10-50 phr of at least one synthetic rubber; (c) 60-70 phr of at least one carbon black; and (d) 7-9 phr of at least one cross-linking agent, said process comprising: (a) obtaining at least one natural rubber; (b) obtaining at least one synthetic rubber; (c) obtaining at least one carbon black; (d) obtaining at least one cross-linking agent; and (e) contacting the at least one natural rubber, the at least one synthetic rubber; the at least one carbon black; and the at least one cross-linking agent to obtain the composition.
[0041] In an embodiment of the present disclosure there is provided a process for preparing a composition for truck and bus radial tire (TBR) belt compound composition comprising (a) 50-100 phr of at least one natural rubber; (b) 10-50 phr of at least one

synthetic rubber; (c) 60-70 phr of at least one carbon black; and (d) 7-9 phr of at least one cross-linking agent, wherein said process comprising: (a) obtaining at least one natural rubber; (b) obtaining at least one synthetic rubber; (c) obtaining at least one carbon black; (d) obtaining at least one cross-linking agent; and (e) contacting the at least one natural rubber, the at least one synthetic rubber; the at least one carbon black; and the at least one cross-linking agent at a temperature in the range of 90° to 100° C for a time period in the range of 2 to 4 mins to obtain the composition.
[0042] In an embodiment of the present disclosure there is provided a process for preparing a composition for truck and bus radial tire (TBR) belt compound comprising (a) 50-100 phr of at least one natural rubber; (b) 10-50 phr of at least one synthetic rubber; (c) 60-70 phr of at least one carbon black; and (d) 7-9 phr of at least one cross-linking agent, said process comprising: (a) obtaining at least one natural rubber; (b) obtaining at least one synthetic rubber; (c) obtaining at least one carbon black; (d) obtaining at least one cross-linking agent; and (e) contacting the at least one natural rubber, the at least one synthetic rubber; the at least one carbon black; and the at least one cross-linking agent to obtain the composition and wherein contacting the at least one natural rubber, the at least one synthetic rubber; the at least one carbon black and the at least one cross-linking agent at a temperature in the range of 90° to 100° C for a time period in the range of 2 to 4 mins to obtain the composition, and wherein the at least one natural rubber is selected from the group consisting of RSS1, RSS2, RSS3, RSS4 and combinations thereof and wherein the at least one synthetic rubber is polyisoprene rubber and wherein the at least one carbon black is selected from the group consisting of carbon black N326, carbon black N358, and combinations thereof and wherein the at least one cross-linking agent is selected from the group consisting of sulfur, insoluble sulfur, and combinations thereof and wherein
[0043] In an embodiment of the present disclosure, there is provided a composition for truck and bus radial tire (TBR) belt compound comprising: (a) 50-100 phr of at least one natural rubber; (b) 10-50 phr of at least one synthetic rubber; (c) 60-70 phr of at

least one carbon black; (d) 7-9 phr of at least one cross-linking agent; and (e) at least one additive selected from the group consisting of at least one adhesion promoter, at least one activator, at least one antioxidant, at least one rubber accelerator, and combinations thereof, said process comprising: (a) obtaining at least one natural rubber; (b) obtaining at least one synthetic rubber; (c) obtaining at least one carbon black; (d) obtaining at least one cross-linking agent; (e) obtaining at least one additive; and (f) contacting the at least one natural rubber, the at least one synthetic rubber, the at least one carbon black, the at least one cross-linking agent, and the at least one additive to obtain the composition.
[0044] In an embodiment of the present disclosure, there is provided a composition for truck and bus radial tire (TBR) belt compound comprising: (a) 50-100 phr of at least one natural rubber; (b) 10-50 phr of at least one synthetic rubber; (c) 60-70 phr of at least one carbon black; (d) 7-9 phr of at least one cross-linking agent; and (e) at least one additive selected from the group consisting of at least one adhesion promoter, at least one activator, at least one antioxidant, at least one rubber accelerator, and combinations thereof, said process comprising: (a) obtaining at least one natural rubber; (b) obtaining at least one synthetic rubber; (c) obtaining at least one carbon black; (d) obtaining at least one cross-linking agent; (e) obtaining at least one additive; and (f) contacting the at least one natural rubber, the at least one synthetic rubber, the at least one carbon black, the at least one cross-linking agent and the at least one additive at a temperature in the range of 90° to 100°C for a time period in the range of 2 to 4 mins to obtain the composition.
[0045] In an embodiment of the present disclosure there is provided a tire comprising a composition for truck and bus radial tire (TBR) belt compound, said composition comprising: (a) 50-100 phr of at least one natural rubber; (b) 10-50 phr of at least one synthetic rubber; (c) 60-70 phr of at least one carbon black and (d) 7-9 phr of at least one cross-linking agent.

[0046] In an embodiment of the present disclosure, there is provided a tire comprising a composition for truck and bus radial tire (TBR) belt compound, said composition comprising (a) 50-100 phr of at least one natural rubber; (b) 10-50 phr of at least one synthetic rubber; (c) 60-70 phr of at least one carbon black; (d) 7-9 phr of at least one cross-linking agent; and (e) at least one additive selected from the group consisting of at least one adhesion promoter, at least one activator, at least one antioxidant, at least one rubber accelerator, and combinations thereof.
[0047] 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
[0048] 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.
[0049] The forthcoming examples explain that how the present disclosure provides a composition for truck and bus radial tire belt compound to achieve improved traction

and physical properties. The truck and bus radial tire belt compound for the present disclosure comprised of at least one natural rubber, at least one synthetic rubber, at least one carbon black, at least one cross-linking agent and at least one additive selected from the group consisting of at least one adhesion promoter, at least one activator, at least one antioxidant and at least one rubber accelerator. The following examples show that how the composition of the present disclosure exhibited enhanced properties with upgraded endurance and lowered dynamic creep, thereby increasing the duration of tires.
MATERIALS REQUIRED
[0050] For the purpose of the present disclosure, following raw materials with the
specified grades/brands were used for obtaining said belt composition.
a) Ribbed Smoked Sheet (RSS3) -Thailand Rubber
b) Synthetic poly isoprene rubber - SKI3 from Nizhnekamskneftekhim.
c) Nickel Catalyzed Poly butadiene rubber - Reliance
d) Carbon black Grades - N326 from PCBL, India.
e) Insoluble sulphur (20% Oil) - Crystex HD OT 20, Eastman.
f) Silica- MFIL200G - Madhu Silica
g) Silane coupling agent - bis[3- (triethoxysilyl)propyl] disulphide - Evonik h) Cobalt salt - Boroacylate - OMG
i) Zinc Oxide – Rubamin ltd
j) Antioxidants – Lanxess India
EXAMPLE1
Process for the preparation of belt compound for the truck and bus radial tires [0051] Belt compound generally contains various components such as natural or synthetic rubber, additive, cross-linking agents and so on. The composition of the present disclosure was prepared with a view to lower the dynamic creep of the belt compound and to increase the tire endurance. This was achieved by varying the

components proportionately such as by reducing the volatile organic components,
increasing carbon black and increasing the sulphur content.
[0052] The composition (herein referred to as C1) of the present disclosure comprised
the various components for the preparation of the belt compound and the components
along with their weight in phr are shown in Table1.
Table 1

Category Components Composition (phr)
Natural Rubber Natural Rubber 80
Synthetic Rubber Synthetic Polyisoprene rubber 20
Carbon black Carbon Black – Primary Iodine Surface Area 77 – 87mg/g 65
Crosslinking agent Insoluble Sulfur 8.5
Additives Adhesion promoter Cobalt Salt 1

Activator Zinc oxide 10

Antioxidants N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylendiamine (6PPD) 1

Accelerator N,N'-Dicyclohexyl-2-benzothiazole sulfonamide (DCBS) 1
[0053] Table 1 shows various components taken in the mentioned proportion for the preparation of the composition of the belt compound of truck and bus radial tires. The components taken for the present composition were 80 phr of natural rubber, 20phr of synthetic polyisoprene rubber, 65 phr of carbon black and the 8.5 phr of insoluble sulfur. The additives such as adhesion promoter, activator, antioxidants, and accelerator were also taken as per Table 1 respectively. For the purpose of mixing the components to prepare the belt compound composition, Banbury mixer & Sheeted out two-roll mill were utilized.

[0054] The composition for truck and bus radial tire belt compound was prepared by the following steps:
1) Synthetic polyisoprene rubber (SKI3 from Nizhnekamskneftekhim), natural rubber (RSS3 -Thailand Rubber) carbon black, cross-linking agent and additives such as the cobalt salt (cobalt boroacylate), zinc oxide, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylendiamine (6PPD) and N,N'-Dicyclohexyl-2-benzothiazole sulfonamide (DCBS) were contacted with each other in the banbury mixer at a temperature in the range of 90° to 100°C for a time period of 2 to 4 minutes to obtain a first mixture.
2) The first mixture was then contacted with sulphur and accelerators to obtain the belt compound.
3) The belt compound as prepared in the banbury mixer was then sheeted out in 6mm in the two-roll mill. The belt compound was then calendered and extruded as per the specification to build a tire.
[0055] The belt compound for the truck and bus radial tires as prepared above was subjected to various analysis of the physical and mechanical properties, wherein the composition was tested for understanding the effect of different ingredients on the belt endurance and the dynamic creep.
EXAMPLE 2
(A) Measurement of dynamic creep and belt endurance
[0056] The belt compound prepared in example 1 was checked for the dynamic creep. The compound obtained was cured with a specified mold and the curing temperature was 148°C for a time duration of 30minutes. Curing was done by the compression molding.
(B) Curing of tire with the belt compound
[0057] The belt compound was cured and checked for the dynamic creep as described in (A) and was further used for tire building. The tire was then cured under specific conditions and was tested for its mechanical properties, and further validation.

(C) Measurement of belt endurance
[0058] The truck and bus radial tires built with the belt compound as obtained from example 1 was then subjected to the indoor endurance test. The percentage of the endurance of the truck/ bus radial tire with the belt compound of the present disclosure was compared with the belt of the regular tires. Subsequently, the percentage improvement in belt endurance was checked.
RESULTS
[0059] The characteristic results of the aforementioned properties (dynamic creep and
percentage of endurance) of the truck/ bus radial tires with the belt compound of the
present disclosure are shown in Table 2.
Table 2:

Properties Working ranges Results
Dynamic Creep Index of the Belt compound 50-80 59
% Belt Endurance Index of the truck/bus radial tire with the belt compound from example 1 105-150 113
[0060] Referring to Table 2, the belt compound as obtained from example 1 shows a dynamic creep of 59 (50-80) and the truck/bus radial tire with the belt compound showed 113% (105-150) of endurance.
[0061] It can be inferred from Table 2, that the belt compound of the present disclosure exhibits lowered dynamic creep and the truck/bus radial tires having said belt compound exhibited an increased endurance. The truck/bus radial tires with increased endurance and lowered creep of belt compound helped to reduce the chances of the belt failure. With reduced belt failure, the ageing properties and life of the tires were also improved.
EXAMPLE 3 Non-working examples

[0062] The present example discloses the belt compound prepared according to the process as described in Example 1. Various compositions as exemplified in below Table 3 were used for preparing different belt compounds of truck and bus radial tires and these belt compounds were subjected to analysis as explained in Example 2. Table 3

Category Components Composition (phr)
C2 C3 C4 C5 C6
Natural Rubber Natural Rubber 100 100 85 100 80
Synthetic Rubber Poly butadiene rubber 0 0 15 0 20

Synthetic Polyisoprene rubber 0 0 0 0 0
Carbon black Carbon Black – Primary Iodine Surface Area 77 – 87mg/g 55 60 20 45 5

Silica 0 0 41 30 55

Silane coupling agent 0 0 3.5 2.5 4
Additives Cobalt Salt (Adhesion promoter) 0.8 0.8 0.8 0.8 0.5

Adhesion promoter resins 0 5.5 1.5 1.5 6

Zinc oxide (Activator) 8 10 10 10 8

Tackifying resin 0 6 4 2.5 9

Antioxidants-6PPD 3 1.5 3 1.5 3.5
Crosslinking agent Sulfur 6.5 5 6 6 4.5
Accelerator DCBS 1 1 2 1.5 2
[0063] Various compositions C2, C3, C4, C5, and C6 for the belt compounds were prepared as per the process as explained in Example 1 and was subjected to the test of dynamic creep and the tire belt endurance as explained in Example 2.
RESULTS
[0064] The characteristics and the aforementioned properties of the belt compound of
compositions C2, C3, C4, C5, and C6 are shown in Table 4.
Table 4

Properties
Composition Dynamic creep of the belt compound % Endurance of
the truck/bus
radial tire with the
belt compound
C2 100 100
C3 118 96
C4 88 102
C5 94 101
C6 106 100
[0065] As shown in Table 3, various components were utilized for the composition C2-C6. These compositions showed different dynamic creep values and percentage of endurance (as shown in Table 4). For instance, due to the absence of synthetic polyisoprene rubber, and utilization of low sulphur in cure system, the compositions C2, C3, C4, C5, and C6 showed dynamic creep of 100, 118, 88, 94 and 106, respectively and the percentage endurance of the truck/ bus radial tire with the belt compound of the composition C2, C3, C4, C5, and C6 was found to be 100, 96, 102, 101 and 100. It can be inferred from Table 4 that the compositions C2, C3, C4, C5, and C6 for the truck/ bus radial tire belt compound exhibited a higher dynamic creep and lowered percentage endurance.
[0066] For the purpose of the present disclosure, when the dynamic creep (59) and percentage of belt endurance (113) of composition C1 was compared with the dynamic creep (100) and percentage of belt endurance (100) of composition C2, the endurance of the belt compound with C1 increased by 13%, and the dynamic creep was also decreased. This indicated that the belt compound with composition C1 exhibited improved rolling resistance.
[0067] Overall, it is important to have all the components of the belt compound of the present disclosure within their disclosed weight ranges in order to have improved properties such as dynamic creep and the tire belt endurance. Particularly, the presence of (a) 50-100 phr of at least one natural rubber; (b) 10-50 phr of at least one synthetic

rubber; (c) 60-70 phr of at least one carbon black; and (d) 7-9 phr of at least one cross-linking agent in a composition of the truck and bus radial belt compound is essential for providing a belt compound with lowered creep value and high endurance. The absence of any of the components as mentioned above, or even deviating from their disclosed weight ranges does not exhibit the desired effect. For instance, due to the absence of synthetic polyisoprene rubber, or by deviating the component such as sulphur from their disclosed weight range (7-9 phr) in compositions C2 (6.5), C3 (5), C4 (6), C5 (6), and C6 (4.5) led the aforementioned compositions to exhibit a higher dynamic creep value and low belt endurance. Therefore, the compositions C2-C6 with higher dynamic creep value and low belt endurance were considered as the non-working examples of the present disclosure and the composition C1 with the low dynamic creep and high belt endurance were considered as the best-working example.
Advantages of the present disclosure
[0068] The present disclosure discloses a composition for truck and bus radial tire (TBR) belt compound comprising: (a) 50-100 phr of at least one natural rubber; (b) 10-50 phr of at least one synthetic rubber; (c) 60-70 phr of at least one carbon black; and (d) 7-9 phr of at least one cross-linking agent. The belt compound obtained by the composition of the present disclosure exhibits a lowered dynamic creep. Consequently, the truck and bus radial tire comprising of the belt compound of the present disclosure exhibits an increased endurance. The lowered creep value and increase endurance help to increase the life of tires by reducing the belt failures in tires. The belt compound of the present composition also found to have improved rolling resistance properties.

I/We Claim:
1) A composition for Truck and Bus Radial tire (TBR) belt compound
comprising:
(a) 50-100 phr of at least one natural rubber;
(b) 10-50 phr of at least one synthetic rubber;
(c) 60-70 phr of at least one carbon black; and
(d) 7-9 phr of at least one cross-linking agent
2) The composition as claimed in claim 1, wherein the at least one natural rubber is selected from the group consisting of RSS1 (Ribbed Smoked Sheet), RSS2, RSS3, RSS4, and combinations thereof.
3) The composition as claimed in claim 1, wherein the at least one synthetic rubber is polyisoprene rubber.
4) The composition as claimed in claim 1, wherein the at least one carbon black is selected from the group consisting of carbon black N326, carbon black N358, and combinations thereof.
5) The composition as claimed in claim 1, wherein the at least one cross-linking agent is selected from the group consisting of sulfur, insoluble sulfur, and combinations thereof.
6) The composition as claimed in claim 1, wherein the composition further comprises at least one additive selected from the group consisting of at least one adhesion promoter, at least one activator, at least one antioxidant, at least one rubber accelerator, and combinations thereof.
7) The composition as claimed in claim 6, wherein the at least one adhesion promoter is selected from the group consisting of cobalt boro acylate, cobalt borate alkanoate, and combinations thereof, having a concentration in the range of 0.5-1 phr; the at least one activator is selected from the group consisting of zinc oxide, active zinc oxide, nano zinc oxide, and combinations thereof, having a concentration in the range of 8-10 phr; the at least one

antioxidant is selected from the group consisting of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylendiamine (6PPD), 2,2,4-trimethyl-l,2-dihydroquinoline (TQ), and combinations thereof, having a concentration in the range of 1.0-2.0 phr, and the at least one rubber accelerator is N,N'-Dicyclohexyl-2-benzothiazole sulfonamide (DCBS), having a concentration in the range of 0.8-1.5 phr.
8) The composition as claimed in any one of the claims 1-7, wherein the composition has a dynamic creep index in the range of 55-65.
9) The composition as claimed in any one of the claims 1-7, wherein the composition has a belt endurance index in the range of 110-115.
10) A process for preparing the composition as claimed in claim 1, said process comprising:

(a) obtaining at least one natural rubber;
(b) obtaining at least one synthetic rubber;
(c) obtaining at least one carbon black;
(d) obtaining at least one cross-linking agent; and
(e) contacting the at least one natural rubber, the at least one synthetic rubber; the at least one carbon black; and the at least one cross-linking agent to obtain the composition.
11) The process as claimed in claim 10, wherein contacting the at least one natural
rubber, the at least one synthetic rubber; the at least one carbon black; and the
at least one cross-linking agent at a temperature in the range of 90° to 100° C
for a time period in the range of 2 to 4 mins to obtain the composition.
12) The process for preparing the composition as claimed in claim 6, said
process comprising:
(a) obtaining at least one natural rubber;
(b) obtaining at least one synthetic rubber;
(c) obtaining at least one carbon black;

(d) obtaining at least one cross-linking agent;
(e) obtaining at least one additive; and
(f) contacting the at least one natural rubber, the at least one synthetic rubber, the at least one carbon black, the at least one cross-linking agent, and the at least one additive to obtain the composition.
13) The process as claimed in claim 12, wherein contacting the at least one natural
rubber, the at least one synthetic rubber, the at least one carbon black, the at
least one cross-linking agent, and the at least one additive at a temperature in
the range of 90° to 100°C for a time period in the range of 2 to 4 mins to obtain
the composition.
14) A tire comprising the composition as claimed in any one of the claims 1-9.