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: ABRASION GUM STRIP RUBBER COMPOSITION
2. Applicant(s)
NAME NATIONALITY ADDRESS
CEAT LIMITED Indian RPG HOUSE, 463, Dr. Annie Besant
Road, Worli, Mumbai 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.

TECHNICAL FIELD
[0001] The subject matter described herein relates to the rubber composition and in particular relates to the rubber composition of abrasion gum strip.
BACKGROUND OF THE INVENTION
[0002] Abrasion Gum Strip (AGS) is a compounded rubber strip that provides a layer of
rubber between the body plies and the wheel rim for resistance against chafing. Abrasion
gum strip is also known as gum chafer or gum toe guards. The objective of using the
abrasion gum strip is to maintain the airtight seal between the tire and rim. Hence, it is
important that the abrasion gum strip is able to withstand all operating conditions with
minimal wear and tear. The various components used for making the rubber composition
for abrasion gum strip includes elastomers, reinforcing fillers, cure packages, viscosity
modifier, retarders, etc.
[0003] In recent years, many improvements have been made to provide the rubber
composition for abrasion gum strip with improved physical and mechanical properties.
For example, the Patent document US5723530A discloses a tire with a tread of elastomer
composition which uses polybutadiene styrene-based, vinyl-based dienes along with
aromatic processing oil and reinforcing fillers with good abrasion properties.
[0004] Another rubber composition used for making abrasion gum strip of a tire is
disclosed in the Patent document WO2016200642A1, wherein the rubber composition
uses conventional high cis-content polybutadiene, at least one viscosity modifier, at least
one reinforcing filler, and a cure package. The document further discloses a method of
preparing the rubber composition.
[0005] Although a lot of efforts have been made to provide the rubber composition of
abrasion gum strip, however, there is still a need in the state of art to provide the rubber
composition of abrasion gum strip having better physical and ageing properties.

SUMMARY OF THE INVENTION
[0006] In an aspect of the present disclosure, there is provided an abrasion gum strip rubber composition comprising a) 30 - 70 phr of at least one polybutadiene rubber; b) 30 - 70 phr of at least one natural rubber; c) 1.0 - 1.5 phr of at least one cross-linking agent; d) 0.3 - 1.0 phr of at least one cure accelerator; and e)1.0 - 2.5 phr of at least one rubber accelerator, wherein the at least one polybutadiene rubber has a cis 1,4-bond content in the range of 35 - 38 wt. %, and the at least one cross-linking agent to the at least one rubber accelerator weight ratio is in the range of 0.4 - 1.5.
[0007] In second aspect of the present disclosure, there is provided a process for preparing an abrasion gum strip rubber composition comprising: a) 30 - 70 phr of at least one polybutadiene rubber; b) 30 - 70 phr of at least one natural rubber; c) 1.0 - 1.5 phr of at least one cross-linking agent; d) 0.3 - 1.0 phr of at least one cure accelerator; and e) 1.0 - 2.5 phr of at least one rubber accelerator, wherein the at least one polybutadiene rubber has a cis 1,4-bond content in the range of 35 - 38 wt. %, and the at least one cross-linking agent to the at least one rubber accelerator weight ratio is in the range of 0.4 - 1.5, said process comprising: (i) contacting 30 - 70 phr of at least one polybutadiene rubber, 30 - 70 phr of at least one natural rubber; 1.5 - 1.0 phr of at least one cross-linking agent, 0.3 - 1.0 phr of at least one cure accelerator, 1.0 - 2.5 phr of at least one rubber accelerator to obtain the abrasion gum strip rubber composition. [0008] In third aspect of the present disclosure, there is provided a process for preparing an abrasion gum strip rubber composition comprising, the said process comprising: (a) 30 - 70 phr of at least one polybutadiene rubber; b) 30 - 70 phr of at least one natural rubber; c) 1.0 - 1.5 phr of at least one cross-linking agent; d) 0.3 - 1.0 phr of at least one cure accelerator; e) 1.0 - 2.5 phr of at least one rubber accelerator; and (f) at least one additive selected from the group consisting of 70 - 85 phr of carbon black, 1 - 8 phr of at least one cure activator, 0.5 - 9 phr of at least one antioxidant, 0 -14 phr of at least one process aid, 0 - 0.5 phr of at least one retarder, and combinations thereof, wherein the at least one polybutadiene rubber has a cis 1,4-bond content in the

range of 35 - 38 wt. %, and the at least one cross-linking agent to the at least one rubber accelerator weight ratio is in the range of 0.4 - 1.5, said process comprising: i) contacting 30 - 70 phr of at least one polybutadiene rubber, 30 - 70 phr of at least one natural rubber; 1.5 - 1.0 phr of at least one cross-linking agent, 0.3 - 1.0 phr of at least one cure accelerator, 1.0 - 2.5 phr of at least one rubber accelerator, 70 - 85 phr of carbon black, 1 - 8 phr of at least one cure activator, 0.5 - 9 phr of at least one antioxidant, 0 - 14 phr of at least one process aid, 0 - 0.5 phr of at least one retarder to obtain the abrasion gum strip rubber composition.
[0009] In fourth aspect of the present disclosure, there is provided a tire comprising the abrasion gum strip rubber composition comprising a) 30 - 70 phr of at least one polybutadiene rubber; b) 30 - 70 phr of at least one natural rubber; c) 1.0 - 1.5 phr of at least one cross-linking agent; d) 0.3 - 1.0 phr of at least one cure accelerator; and e)1.0 - 2.5 phr of at least one rubber accelerator, wherein the at least one polybutadiene rubber has a cis 1,4-bond content in the range of 35 - 38 wt. %, and the at least one cross-linking agent to the at least one rubber accelerator weight ratio is in the range of 0.4 - 1.5.
[0010] 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
[0011] 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
[0012] 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.
[0013] 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.
[0014] 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”.
[0015] 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.
[0016] The term “including” is used to mean “including but not limited to”.
“Including” and “including but not limited to” are used interchangeably.
[0017] 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 surface area range
of about 73-83 m2/g should be interpreted to include not only the explicitly recited
limits of about 73 m2/g to about 83 m2/g but also to include sub-ranges, such as 73-82

m2/g, 74-83m2/g and so forth, as well as individual amounts, including fractional amounts, within the specified ranges, such as 73.5m2/g, and 82.5 m2/g for example. [0018] The term “at least one” is used to mean one or more and thus includes individual components as well as mixtures/combinations.
[0019] For the purposes of the present disclosure, the term “phr” refers to parts per hundred rubber, it is a unit well used in the field of rubber technology to define the amount of ingredients used.
[0020] 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.
[0021] 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.
[0022] Conventionally, the Abrasion Gum Strip (AGS) formulation used as compounded rubber strip employs natural rubber, butadiene rubber blend and cross-linking system having sulphur and accelerator, wherein the butadiene rubber is a high cis-content butadiene rubber having a concentration in the range of 96% or above, and wherein the sulphur to the accelerator weight ratio is in the range of 2.0 or more. When such Abrasion Gum Strip comes in contact with the tire and vehicle, it experiences a very high temperature (160-200°C) during curing of the tire which leads to the reversion of torque property (rheological property). Additionally, due to environmental ageing and upon tire usage, tensile strength and elongation to break also get reduced. Due to the changes in the dynamic properties of the tire, AGS become brittle and starts cracking. This problem becomes very severe in tubeless tires because in tubeless tire there is no tube and once

AGS is cracked or cut, air can bleed out from tire, thereby, resulting in complete functionality loss of the tire.
[0023] In the view of the shortcomings of the prior art, it can be understood that there is a need in the state of art for the abrasion gum strip rubber composition that exhibits improved properties. The present disclosure provides a rubber composition that overcomes the above said shortcomings of the prior arts. The abrasion gum strip rubber composition comprises of one polybutadiene rubber with a relatively lower cis 1,4 bond along with the natural rubber.
[0024] The abrasion gum strip rubber composition of the present disclosure comprises at least one polybutadiene rubber; b) 30 - 70 phr of at least one natural rubber; c) 1.0 - 1.5 phr of at least one cross-linking agent; d) 0.3 -1.0 phr of at least one cure accelerator; and e) 1.0 - 2.5 phr of at least one rubber accelerator, wherein the at least one polybutadiene rubber has a cis 1,4-bond content in the range of 35 - 38 wt. %, and the at least one cross-linking agent to the at least one rubber accelerator weight ratio is in the range of 0.4 - 1.5. The abrasion gum strip of the present disclosure shows a low reversion index, better tensile strength, and elongation at break after ageing. Therefore, the present disclosure provides the rubber composition that enables the abrasion gum strip to remain free from cracks and cuts during the tire service life.
[0025] In an embodiment of the present disclosure, there is provided an abrasion gum strip rubber composition comprising: a) 30 - 70 phr of at least one polybutadiene rubber; b) 30 - 70 phr of at least one natural rubber; c) 1.0 - 1.5 phr of at least one cross-linking agent; d) 0.3 -1.0 phr of at least one cure accelerator; and e) 1.0 - 2.5 phr of at least one rubber accelerator, wherein the at least one polybutadiene rubber has a cis 1,4-bond content in the range of 35 - 38 wt. %, and the at least one cross-linking agent to the at least one rubber accelerator weight ratio is in the range of 0.4 - 1.5. [0026] In an embodiment of the present disclosure, there is provided an abrasion gum strip rubber composition comprising: a) 30 - 70 phr of at least one polybutadiene rubber; b) 30 - 70 phr of at least one natural rubber; c) 1.0 - 1.5 phr of at least one cross-

linking agent; d) 0.3 -1.0 phr of at least one cure accelerator; and e) 1.0 - 2.5 phr of at least one rubber accelerator, wherein the at least one polybutadiene rubber has a cis 1,4-bond content in the range of 35 - 38 wt. %, and the at least one cross-linking agent to the at least one rubber accelerator weight ratio is in the range of 0.4 - 1.5. In another embodiment of the present disclosure, the at least one cross-linking agent to the at least one rubber accelerator weight ratio is in the range of 0.5-1.2.
[0027] In an embodiment of the present disclosure, there is provided an abrasion gum strip rubber composition comprising: a) 40 - 60 phr of at least one polybutadiene rubber; b) 40 - 60 phr of at least one natural rubber; c) 1 - 1.15 phr of at least one cross-linking agent; d) 0.4 - 1.0 phr of at least one cure accelerator; and e) 1.2 - 2.3 phr of at least one rubber accelerator, wherein the at least one polybutadiene rubber has a cis 1,4-bond content in the range of 35 - 38 wt. %, and the at least one cross-linking agent to the at least one rubber accelerator weight ratio is in the range of 0.4 - 1.5. [0028] In an embodiment of the present disclosure, there is provided an abrasion gum strip rubber composition comprising: a) 30 - 70 phr of at least one polybutadiene rubber; b) 30 - 70 phr of at least one natural rubber; c) 1.0 - 1.5 phr of at least one cross-linking agent; d) 0.3 -1.0 phr of at least one cure accelerator; and e) 1.0 - 2.5 phr of at least one rubber accelerator, wherein the at least one polybutadiene rubber has a cis 1,4-bond content in the range of 36 - 38 wt. %, and the at least one cross-linking agent to the at least one rubber accelerator weight ratio is in the range of 0.4 - 1.5. [0029] In an embodiment of the present disclosure, there is provided an abrasion gum strip rubber composition comprising: a) 30 - 70 phr of at least one polybutadiene rubber; b) 30 - 70 phr of at least one natural rubber; c) 1.0 - 1.5 phr of at least one cross-linking agent; d) 0.3 -1.0 phr of at least one cure accelerator; and e) 1.0 - 2.5 phr of at least one rubber accelerator, wherein the at least one polybutadiene rubber has a cis 1,4-bond content in the range of 35 - 38 wt. %, and the at least one cross-linking agent to the at least one rubber accelerator weight ratio is in the range of 0.4 - 1.5 and wherein the at least one polybutadiene rubber is selected from the group consisting of lithium

butadiene rubber (Li-BR), cobalt butadiene rubber (Co-BR), nickel- butadiene rubber (Ni-BR), neodymium butadiene rubber (Nd-BR), and combinations thereof. In another embodiment of the present disclosure, the at least one polybutadiene rubber is lithium butadiene rubber.
[0030] In an embodiment of the present disclosure, there is provided an abrasion gum strip rubber composition comprising: a) 30 - 70 phr of at least one polybutadiene rubber; b) 30 - 70 phr of at least one natural rubber; c) 1.0 - 1.5 phr of at least one cross-linking agent; d) 0.3 -1.0 phr of at least one cure accelerator; and e) 1.0 - 2.5 phr of at least one rubber accelerator, wherein the at least one polybutadiene rubber has a cis 1,4-bond content in the range of 35 - 38 wt. %, and the at least one cross-linking agent to the at least one rubber accelerator weight ratio is in the range of 0.4 - 1.5 and wherein the at least one natural rubber is selected from the group consisting of ribbed smoked sheets, technically specified natural rubber, polyisoprene rubber, and combinations thereof. In another embodiment of the present disclosure, the at least one natural rubber is TSR20. In yet another embodiment of the present disclosure, the at least one natural rubber is TSR3L.
[0031] In an embodiment of the present disclosure, there is provided an abrasion gum strip rubber composition comprising: a) 30 - 70 phr of at least one polybutadiene rubber; b) 30 - 70 phr of at least one natural rubber; c) 1.0 - 1.5 phr of at least one cross-linking agent; d) 0.3 -1.0 phr of at least one cure accelerator; and e) 1.0 - 2.5 phr of at least one rubber accelerator, wherein the at least one polybutadiene rubber has a cis 1,4-bond content in the range of 35 - 38 wt. %, and the at least one cross-linking agent to the at least one rubber accelerator weight ratio is in the range of 0.4 - 1.5 and wherein the at least one cross-linking agent is selected from the group consisting of sulphur, soluble sulphur, insoluble sulphur, and combinations thereof. In another embodiment of the present disclosure, the at least one cross-linking agent is sulphur.
[0032] In an embodiment of the present disclosure, there is provided an abrasion gum strip rubber composition comprising: a) 30 - 70 phr of at least one polybutadiene

rubber; b) 30 - 70 phr of at least one natural rubber; c) 1.0 - 1.5 phr of at least one cross-linking agent; d) 0.3 -1.0 phr of at least one cure accelerator; and e) 1.0 - 2.5 phr of at least one rubber accelerator, wherein the at least one polybutadiene rubber has a cis 1,4-bond content in the range of 35 - 38 wt. %, and the at least one cross-linking agent to the at least one rubber accelerator weight ratio is in the range of 0.4 - 1.5 and wherein the at least one cure accelerator is 1,6-Bis (N,N-dibenzylthiocarbamoyldithio) hexane. [0033] In an embodiment of the present disclosure, there is provided an abrasion gum strip rubber composition comprising: a) 30 - 70 phr of at least one polybutadiene rubber; b) 30 - 70 phr of at least one natural rubber; c) 1.0 - 1.5 phr of at least one cross-linking agent; d) 0.3 -1.0 phr of at least one cure accelerator; and e) 1.0 - 2.5 phr of at least one rubber accelerator, wherein the at least one polybutadiene rubber has a cis 1,4-bond content in the range of 35 - 38 wt. %, and the at least one cross-linking agent to the at least one rubber accelerator weight ratio is in the range of 0.4 - 1.5 and wherein the at least one rubber accelerator is selected from the group consisting of N-tert-butyl-2-benzothiazyl sulfonamide (TBBS), N-cyclohexyl -2- benzothiazole sulfonamide, N-oxydienthylene-2-benzothiazole sulfenamide, and combinations thereof. In another embodiment of the present disclosure, the at least one rubber accelerator is N-tert-butyl-2-benzothiazyl sulfonamide.
[0034] In an embodiment of the present disclosure, there is provided an abrasion gum strip rubber composition comprising: a) 30 - 70 phr of at least one polybutadiene rubber; b) 30 - 70 phr of at least one natural rubber; c) 1.0 - 1.5 phr of at least one cross-linking agent; d) 0.3 -1.0 phr of at least one cure accelerator; and e) 1.0 - 2.5 phr of at least one rubber accelerator, wherein the at least one polybutadiene rubber has a cis 1,4-bond content in the range of 35 - 38 wt. %, and the at least one cross-linking agent to the at least one rubber accelerator weight ratio is in the range of 0.4 - 1.5, and wherein the at least one polybutadiene rubber is selected from the group consisting of lithium butadiene rubber (Li-BR), cobalt butadiene rubber (Co-BR), nickel- butadiene rubber (Ni-BR), neodymium butadiene rubber (Nd-BR), and combinations thereof, and

wherein the at least one natural rubber is selected from the group consisting of ribbed smoked sheets, technically specified natural rubber, polyisoprene rubber, and combinations thereof and wherein the at least one cross-linking agent is selected from the group consisting of sulphur, soluble sulphur, insoluble sulphur, and combinations thereof.
[0035] In an embodiment of the present disclosure, there is provided an abrasion gum strip rubber composition comprising: a) 30 - 70 phr of at least one polybutadiene rubber; b) 30 - 70 phr of at least one natural rubber; c) 1.0 - 1.5 phr of at least one cross-linking agent; d) 0.3 -1.0 phr of at least one cure accelerator; and e) 1.0 - 2.5 phr of at least one rubber accelerator, wherein the at least one polybutadiene rubber has a cis 1,4-bond content in the range of 35 - 38 wt. %, and the at least one cross-linking agent to the at least one rubber accelerator weight ratio is in the range of 0.4 - 1.5 , and wherein the at least one polybutadiene rubber is selected from the group consisting of lithium butadiene rubber (Li-BR), cobalt butadiene rubber (Co-BR), nickel- butadiene rubber (Ni-BR), neodymium butadiene rubber (Nd-BR), and combinations thereof, and wherein the at least one natural rubber is selected from is selected from the group consisting of ribbed smoked sheets, technically specified natural rubber, polyisoprene rubber, and combinations thereof, and wherein the at least one cross-linking agent is selected from the group consisting of sulphur, soluble sulphur, insoluble sulphur, and combinations thereof, and wherein the at least one cure accelerator is 1,6-Bis (N,N-dibenzylthiocarbamoyldithio) hexane and wherein the at least one rubber accelerator is selected from the group consisting of N-tert-butyl-2-benzothiazyl sulfonamide (TBBS), N-cyclohexyl -2- benzothiazole sulfonamide, N-oxydienthylene-2-benzothiazole sulfenamide, and combinations thereof.
[0036] In an embodiment of the present disclosure, there is provided an abrasion gum strip rubber composition comprising: a) 30 - 70 phr of at least one polybutadiene rubber; b) 30 - 70 phr of at least one natural rubber; c)1.0 - 1.5 phr of at least one cross-linking agent; d) 0.3 -1.0 phr of at least one cure accelerator; e) 1.0 - 2.5 phr of at least

one rubber accelerator, and (f) at least one additive selected from the group consisting of 70 – 85 phr of carbon black, 1 – 8 phr of at least one cure activator, 0.5 – 9 phr of at least one antioxidant, 0 – 14 phr of at least one process aid, 0 – 0.5 phr of at least one retarder, and combinations thereof, wherein the at least one polybutadiene rubber has a cis 1,4-bond content in the range of 35 - 38 wt. %, and the at least one cross-linking agent to the at least one rubber accelerator weight ratio is in the range of 0.4 - 1.5. [0037] In an embodiment of the present disclosure, there is provided an abrasion gum strip rubber composition comprising: a) 30 - 70 phr of at least one polybutadiene rubber; b) 30 - 70 phr of at least one natural rubber; c) 1.0 - 1.5 phr of at least one cross-linking agent; d) 0.3 -1.0 phr of at least one cure accelerator; e) 1.0 - 2.5 phr of at least one rubber accelerator; and (f) at least one additive selected from the group consisting of 70 – 85 phr of carbon black, 1 – 8 phr of at least one cure activator, 0.5 – 9 phr of at least one antioxidant, 0 – 14 phr of at least one process aid, 0 – 0.5 phr of at least one retarder, and combinations thereof, wherein the at least one polybutadiene rubber has a cis 1,4-bond content in the range of 35 - 38 wt. %, and the at least one cross-linking agent to the at least one rubber accelerator weight ratio is in the range of 0.4 - 1.5, and wherein the at least one cure activator is selected from the group consisting of zinc oxide, stearic acid, and combinations thereof; the at least one antioxidant is selected from the group consisting of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylendiamine (6PPD), mixed aryl p-phenylene diamines (PPD) includes N,N’-diphenyl-p-phenylene diamine, N,N’-ditolyl-p-phenylene diamine, N-phenyl-N’-tolyl-p-phenylene diamine, 2,2,4-trimethyl-l,2-dihydroquinoline (TQ), and combinations thereof; the at least one process aid is selected from the group consisting of phenol formaldehyde (PF) resin, C5-30 hydrocarbon resin, wax, naphthenic oil, and combinations thereof and the at least one retarder is N-cyclohexylthio-phthalimide.
[0038] In an embodiment of the present disclosure, there is provided an abrasion gum strip rubber composition comprising: a) 30 - 70 phr of at least one polybutadiene rubber; b) 30 - 70 phr of at least one natural rubber; c) 1.0 - 1.5 phr of at least one cross-

linking agent; d) 0.3 -1.0 phr of at least one cure accelerator; e) 1.0 - 2.5 phr of at least one rubber accelerator, and (f) at least one additive selected from the group consisting of 70 – 85 phr of carbon black, 1 – 8 phr of at least one cure activator, 0.5 – 9 phr of at least one antioxidant, 0 – 14 phr of at least one process aid, 0 – 0.5 phr of at least one retarder, and combinations thereof, wherein the at least one polybutadiene rubber has a cis 1,4-bond content in the range of 35 - 38 wt. %, and the at least one cross-linking agent to the at least one rubber accelerator weight ratio is in the range of 0.4 - 1.5, and wherein the carbon black has a surface area in the range of 73 – 83 m2/g.
[0039] In an embodiment of the present disclosure, there is provided an abrasion gum strip rubber composition comprising: a) 30 - 70 phr of at least one polybutadiene rubber; b) 30 - 70 phr of at least one natural rubber; c) 1.0 - 1.5 phr of at least one cross-linking agent; d) 0.3 -1.0 phr of at least one cure accelerator; e) 1.0 - 2.5 phr of at least one rubber accelerator, and (f) at least one additive selected from the group consisting of 70 – 85 phr of carbon black, 1 – 8 phr of at least one cure activator, 0.5 – 9 phr of at least one antioxidant, 0 – 14 phr of at least one process aid, 0 – 0.5 phr of at least one retarder, and combinations thereof, wherein the at least one polybutadiene rubber has a cis 1,4-bond content in the range of 35 - 38 wt. %, and the at least one cross-linking agent to the at least one rubber accelerator weight ratio is in the range of 0.4 - 1.5 and wherein the carbon black has a surface area in the range of 73 – 83 m2/g and wherein the at least one cure activator is selected from the group consisting of zinc oxide, stearic acid, and combinations thereof; the at least one antioxidant is selected from the group consisting of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylendiamine (6PPD), mixed aryl p-phenylene diamines (PPD) includes N,N’-diphenyl-p-phenylene diamine, N,N’-ditolyl-p-phenylene diamine, N-phenyl-N’-tolyl-p-phenylene diamine, 2,2,4-trimethyl-l,2-dihydroquinoline (TQ), and combinations thereof; at least one process aid is selected from the group consisting of phenol formaldehyde (PF) resin, C5-30 hydrocarbon resin, naphthenic oil, and combinations thereof and the at least one retarder is N-cyclohexylthio-phthalimide.

[0040] In an embodiment of the present disclosure, there is provided an abrasion gum strip rubber composition comprising: a) 30 - 70 phr of at least one polybutadiene rubber; b) 30 - 70 phr of at least one natural rubber; c) 1.0 - 1.5 phr of at least one cross-linking agent; d) 0.3 -1.0 phr of at least one cure accelerator; and e) 1.0 - 2.5 phr of at least one rubber accelerator, wherein the at least one polybutadiene rubber has a cis 1,4-bond content in the range of 35 - 38 wt. %, and the at least one cross-linking agent to the at least one rubber accelerator weight ratio is in the range of 0.4 - 1.5 and wherein the composition has reversion index in the range of 1- 4% at a temperature of 160 ℃. In another embodiment of the present disclosure, the composition has a reversion index in the range 2-4% at a temperature of 160 ℃. In yet another embodiment of the present disclosure, the composition has a reversion index in the range 2.5-3.5% at a temperature of 160 ℃.
[0041] In an embodiment of the present disclosure, there is provided an abrasion gum strip rubber composition comprising: a) 30 - 70 phr of at least one polybutadiene rubber; b) 30 - 70 phr of at least one natural rubber; c) 1.0 - 1.5 phr of at least one cross-linking agent; d) 0.3 -1.0 phr of at least one cure accelerator; and e) 1.0 - 2.5 phr of at least one rubber accelerator, wherein the at least one polybutadiene rubber has a cis 1,4-bond content in the range of 35 - 38 wt. %, and the at least one cross-linking agent to the at least one rubber accelerator weight ratio is in the range of 0.4 - 1.5, and wherein the composition has a tensile strength in the range of 187-220 kg/cm2. In another embodiment of the present disclosure, the composition has a tensile strength in the range of 190-215 kg/cm2. In yet another embodiment of the present disclosure, the composition has a tensile strength in the range of 200-210 kg/cm2. [0042] In an embodiment of the present disclosure, there is provided an abrasion gum strip rubber composition comprising: a) 30 - 70 phr of at least one polybutadiene rubber; b) 30 - 70 phr of at least one natural rubber; c) 1.0 - 1.5 phr of at least one cross-linking agent; d) 0.3 -1.0 phr of at least one cure accelerator; and e) 1.0 - 2.5 phr of at least one rubber accelerator, wherein the at least one polybutadiene rubber has a cis

1,4-bond content in the range of 35 - 38 wt. %, and the at least one cross-linking agent to the at least one rubber accelerator weight ratio is in the range of 0.4 - 1.5, and wherein the composition has an elongation to break percentage in a range of 300-450 %. In another embodiment of the present disclosure, the composition has an elongation to break percentage in a range of 310-400%. In yet another embodiment of the present disclosure, the composition has an elongation to break percentage in a range of 320-380 %.
[0043] In an embodiment of the present disclosure, there is provided an abrasion gum strip rubber composition comprising: a) 30 - 70 phr of at least one polybutadiene rubber; b) 30 - 70 phr of at least one natural rubber; c) 1.0 - 1.5 phr of at least one cross-linking agent; d) 0.3 -1.0 phr of at least one cure accelerator; and e) 1.0 - 2.5 phr of at least one rubber accelerator, wherein the at least one polybutadiene rubber has a cis 1,4-bond content in the range of 35 - 38 wt. %, and the at least one cross-linking agent to the at least one rubber accelerator weight ratio is in the range of 0.4 - 1.5, and wherein the composition has reversion index in the range of 1 - 4 % at a temperature of 160 ℃, and wherein the composition has tensile strength in the range of 187-220 kg/cm2 and wherein the composition has elongation to break percentage in a range of 300-450 %. [0044] In an embodiment of the present disclosure, there is provided an abrasion gum strip rubber composition comprising: a) 30 - 70 phr of at least one polybutadiene rubber; b) 30 - 70 phr of at least one natural rubber; c) 1.0 - 1.5 phr of at least one cross-linking agent; d) 0.3 -1.0 phr of at least one cure accelerator; e) 1.0 - 2.5 phr of at least one rubber accelerator, and (f) at least one additive selected from the group consisting of 70 - 85 phr of carbon black, 1 - 8 phr of at least one cure activator, 0.5 - 9 phr of at least one antioxidant, 0 - 14 phr of at least one process aid, 0 - 0.5 phr of at least one retarder, and combinations thereof, wherein the at least one polybutadiene rubber has a cis 1,4-bond content in the range of 35 - 38 wt. %, and the at least one cross-linking agent to the at least one rubber accelerator weight ratio is in the range of 0.4 - 1.5, and wherein the at least one polybutadiene rubber is selected from the group consisting of

lithium butadiene rubber (Li-BR), cobalt butadiene rubber (Co-BR), nickel- butadiene rubber (Ni-BR), neodymium butadiene rubber (Nd-BR), and combinations thereof and wherein the at least one natural rubber is selected from the group consisting of ribbed smoked sheets, technically specified natural rubber, polyisoprene rubber, and combinations thereof and wherein the at least one cross-linking agent is selected from the group consisting of sulphur, soluble sulphur, insoluble sulphur, and combinations thereof and wherein the at least one cure accelerator is 1,6-Bis (N,N-dibenzylthiocarbamoyldithio) hexane and wherein the at least one rubber accelerator is selected from the group consisting of N-tert-butyl-2-benzothiazyl sulfonamide (TBBS), N-cyclohexyl -2- benzothiazole sulfonamide, N-oxydienthylene-2-benzothiazole sulfenamide, and combinations thereof.
[0045] In an embodiment of the present disclosure, there is provided an abrasion gum strip rubber composition comprising: a) 30 - 70 phr of at least one polybutadiene rubber; b) 30 - 70 phr of at least one natural rubber; c) 1.0 - 1.5 phr of at least one cross-linking agent; d) 0.3 -1.0 phr of at least one cure accelerator; e) 1.0 - 2.5 phr of at least one rubber accelerator, and (f) at least one additive selected from the group consisting of 70 - 85 phr of carbon black, 1 - 8 phr of at least one cure activator, 0.5 - 9 phr of at least one antioxidant, 0 - 14 phr of at least one process aid, 0 - 0.5 phr of at least one retarder, and combinations thereof, wherein the at least one polybutadiene rubber has a cis 1,4-bond content in the range of 35 - 38 wt. %, and the at least one cross-linking agent to the at least one rubber accelerator weight ratio is in the range of 0.4 - 1.5 and wherein the composition has reversion index in the range of 1 - 4 % at a temperature of 160 ℃.
[0046] In an embodiment of the present disclosure, there is provided an abrasion gum strip rubber composition comprising: a) 30 - 70 phr of at least one polybutadiene rubber; b) 30 - 70 phr of at least one natural rubber; c) 1.0 - 1.5 phr of at least one cross-linking agent; d) 0.3 -1.0 phr of at least one cure accelerator; e) 1.0 - 2.5 phr of at least one rubber accelerator, and (f) at least one additive selected from the group consisting

of 70 – 85 phr of carbon black, 1 – 8 phr of at least one cure activator, 0.5 – 9 phr of at least one antioxidant, 0 – 14 phr of at least one process aid, 0 – 0.5 phr of at least one retarder, and combinations thereof, wherein the at least one polybutadiene rubber has a cis 1,4-bond content in the range of 35 - 38 wt. %, and the at least one cross-linking agent to the at least one rubber accelerator weight ratio is in the range 0.4 - 1.5 and wherein the composition has a tensile strength in the range of 187-220 kg/cm2. [0047] In an embodiment of the present disclosure, there is provided an abrasion gum strip rubber composition comprising: a) 30 - 70 phr of at least one polybutadiene rubber; b) 30 - 70 phr of at least one natural rubber; c) 1.0 - 1.5 phr of at least one cross-linking agent; d) 0.3 -1.0 phr of at least one cure accelerator; e) 1.0 - 2.5 phr of at least one rubber accelerator, and (f) at least one additive selected from the group consisting of 70 – 85 phr of carbon black, 1 – 8 phr of at least one cure activator, 0.5 – 9 phr of at least one antioxidant, 0 – 14 phr of at least one process aid, 0 – 0.5 phr of at least one retarder, and combinations thereof, wherein the at least one polybutadiene rubber has a cis 1,4-bond content in the range of 35 - 38 wt. %, and the at least one cross-linking agent to the at least one rubber accelerator weight ratio is in the range of 0.4 - 1.5 and wherein the composition has an elongation to break percentage in a range of 300-450 %.
[0048] In an embodiment of the present disclosure, there is provided an abrasion gum strip rubber composition comprising: a) 30 - 70 phr of at least one polybutadiene rubber; b) 30 - 70 phr of at least one natural rubber; c) 1.0 - 1.5 phr of at least one cross-linking agent; d) 0.3 -1.0 phr of at least one cure accelerator; e) 1.0 - 2.5 phr of at least one rubber accelerator, and (f) at least one additive selected from the group consisting of 70 – 85 phr of carbon black, 1 – 8 phr of at least one cure activator, 0.5 – 9 phr of at least one antioxidant, 0 – 14 phr of at least one process aid, 0 – 0.5 phr of at least one retarder, and combinations thereof, wherein the at least one polybutadiene rubber has a cis 1,4-bond content in the range of 35 - 38 wt. %, and the at least one cross-linking agent to the at least one rubber accelerator weight ratio is in the range of 0.4 - 1.5 , and

wherein the composition has elongation to break percentage in a range of 300-450 % , and wherein the composition has reversion index in the range of 1 – 4% at a temperature of 160 ℃ and wherein the composition has tensile strength in the range of 187-220 kg/cm2 and wherein the composition has elongation to break percentage in a range of 300-450 %.
[0049] In an embodiment of the present disclosure, there is provided a process for preparing an abrasion gum strip rubber composition comprising: a) 30 - 70 phr of at least one polybutadiene rubber; b) 30 - 70 phr of at least one natural rubber; c)1.0 - 1.5 phr of at least one cross-linking agent; d) 0.3 - 1.0 phr of at least one cure accelerator; and e) 1.0 - 2.5 phr of at least one rubber accelerator, wherein the at least one polybutadiene rubber has a cis 1,4-bond content in the range of 35 - 38 wt. % and the at least one cross-linking agent to the at least one rubber accelerator weight ratio is in the range of 0.4 - 1.5, said process comprising: (i) contacting 30 – 70 phr of at least one polybutadiene rubber, 30 – 70 phr of at least one natural rubber; 1.5 – 1.0 phr of at least one cross-linking agent, 0.3 - 1.0 phr of at least one cure accelerator, and 1.0 - 2.5 phr of at least one rubber accelerator to obtain the abrasion gum strip rubber composition. [0050] In an embodiment of the present disclosure, there is provided a process for preparing an abrasion gum strip rubber composition comprising: a) 30 - 70 phr of at least one polybutadiene rubber; b) 30 - 70 phr of at least one natural rubber; c) 1.0 - 1.5 phr of at least one cross-linking agent; d) 0.3 - 1.0 phr of at least one cure accelerator; e) 1.0 - 2.5 phr of at least one rubber accelerator, and (f) at least one additive selected from the group consisting of 70 – 85 phr of carbon black, 1 – 8 phr of at least one cure activator, 0.5 – 9 phr of at least one antioxidant, 0 – 14 phr of at least one process aid, 0 – 0.5 phr of at least one retarder, and combinations thereof, wherein the at least one polybutadiene rubber has a cis 1,4-bond content in the range of 35 - 38 wt. % and the at least one cross-linking agent to the at least one rubber accelerator weight ratio is in the range of 0.4 - 1.5, said process comprising: (i) contacting 30 – 70 phr of at least one polybutadiene rubber, 30 – 70 phr of at least one natural rubber; 1.5 – 1.0 phr of at least

one cross-linking agent, 0.3 - 1.0 phr of at least one cure accelerator, 1.0 - 2.5 phr of at least one rubber accelerator, 70 – 85 phr of carbon black, 1 – 8 phr of at least one cure activator, 0.5 – 9 phr of at least one antioxidant, 0 – 14 phr of at least one process aid, 0 – 0.5 phr of at least one retarder to obtain the abrasion gum strip rubber composition. [0051] In an embodiment of the present disclosure, there is provided a tire comprising the abrasion gum strip rubber composition comprising: a) 30 - 70 phr of at least one polybutadiene rubber; b) 30 - 70 phr of at least one natural rubber; c) 1.0 - 1.5 phr of at least one cross-linking agent; d) 0.3 -1.0 phr of at least one cure accelerator; and e) 1.0 - 2.5 phr of at least one rubber accelerator, wherein the at least one polybutadiene rubber has a cis 1,4-bond content in the range of 35 - 38 wt. %. In another embodiment of the present disclosure, the tire is a tubeless tire.
[0052] In an embodiment of the present disclosure, there is provided a tire comprising an abrasion gum strip rubber composition comprising: a) 30 - 70 phr of at least one polybutadiene rubber; b) 30 - 70 phr of at least one natural rubber; c) 1.0 - 1.5 phr of at least one cross-linking agent; d) 0.3 -1.0 phr of at least one cure accelerator; and e) 1.0 - 2.5 phr of at least one rubber accelerator, wherein the at least one polybutadiene rubber has a cis 1,4-bond content in the range of 35 - 38 wt % and the at least one cross-linking agent to the at least one rubber accelerator weight ratio is in the range of 0.4 -1.5 and wherein the process for preparing the abrasion gum strip rubber composition comprising: (i) contacting 30 – 70 phr of at least one polybutadiene rubber, 30 – 70 phr of at least one natural rubber; 1.5 – 1.0 phr of at least one cross-linking agent, 0.3 - 1.0 phr of at least one cure accelerator, and 1.0 - 2.5 phr of at least one rubber accelerator to obtain the abrasion gum strip rubber composition.
[0053] In an embodiment of the present disclosure, there is provided a tire comprising an abrasion gum strip rubber composition comprising: a) 30 - 70 phr of at least one polybutadiene rubber; b) 30 - 70 phr of at least one natural rubber; c) 1.0 - 1.5 phr of at least one cross-linking agent; d) 0.3 - 1.0 phr of at least one cure accelerator; e) 1.0 - 2.5 phr of at least one rubber accelerator, and (f) at least one additive selected from

the group consisting of 70 – 85 phr of carbon black, 1 – 8 phr of at least one cure activator, 0.5 – 9 phr of at least one antioxidant, 0 – 14 phr of at least one process aid, 0 – 0.5 phr of at least one retarder, and combinations thereof, wherein the at least one polybutadiene rubber has a cis 1,4-bond content in the range of 35 - 38 wt % and the at least one cross-linking agent to the at least one rubber accelerator weight ratio is in the range of 0.4 - 1.5, and wherein the process for preparing the abrasion gum strip rubber composition comprising: (i) contacting 30 – 70 phr of at least one polybutadiene rubber, 30 – 70 phr of at least one natural rubber; 1.5 – 1.0 phr of at least one cross-linking agent, 0.3 - 1.0 phr of at least one cure accelerator, 1.0 - 2.5 phr of at least one rubber accelerator, 70 – 85 phr of carbon black, 1 – 8 phr of at least one cure activator, 0.5 – 9 phr of at least one antioxidant, 0 – 14 phr of at least one process aid, 0 – 0.5 phr of at least one retarder to obtain the abrasion gum strip rubber composition. [0054] 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
[0055] 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.
[0056] The forthcoming examples explain how the present disclosure provides a rubber composition for the abrasion gum strip to achieve an upgraded curing and physical properties. The composition of the present disclosure exhibits enhanced properties by lowering the reversion index with improved retention of tensile strength and elongation at break.
MATERIALS REQUIRED
[0057] For the purpose of the present disclosure, following raw material grades were required: TSR20 – Standard Thailand Rubber – 20 procured from Thailand, Poly Butadiene Rubber – Low cis (Lithium based catalyst) – Grade 710S from KKPC, Poly Butadiene Rubber – Low cis (Lithium based catalyst) – Grade Buna CB45 from Lanxess, Carbon black Grades – N330 from PCBL, India, 1,6-bis(N,N-dibenzylthiocarbamoyldithio)-hexane-Grade Vulcuren 9188 from Lanxess.
EXAMPLE 1
Process for the preparation of an abrasion gum strip rubber composition
[0058] The abrasion gum strip composition of the present disclosure was prepared to
have the components as shown in Table 1
Table 1: Composition of various components utilized in parts by weight for the
preparation of the abrasion gum strip rubber composition.

Category Components Parts by Weight
Poly Butadiene Rubber Low cis (Lithium based catalyst) 50
Natural Rubber Block (TSR-20) 50

Additive Carbon Black -Primary; BET Surface Area 78 ± 5 m2/g 78

Cure activator Zinc oxide 4.5

Stearic acid 3.0

Antioxidant N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylendiamine (6PPD) 1.20

Mixed aryl p-phenylene diamines (PPD) 0.60

2,2,4-trimethyl-l,2-dihydroquinoline (TQ) 2.0

Process aid Wax 0.80

PF Resin 2.0

Hydrocarbon resin 2.0

Naphthenic oil 3.0
Cross-linking agent Sulfur 1.05
Cure accelerator 1,6-bis(N,N-dibenzylthiocarbamoyld ithio)-hexane 0.40
Rubber accelerator N-tert-butyl-2-benzothiazyl sulfonamide (TBBS) 2.1
Retarder Cyclohexylthio phthalimide 0.3
[0059] Table 1 provides an example of the various components taken in the mentioned proportion for the preparation of the abrasion gum strip rubber composition. For the

purpose of mixing the components to prepare the abrasion gum strip composition,
Banbury mixer & Sheeted out two-roll mill were utilized.
[0060] The abrasion gum strip rubber composition was prepared by the following
steps:
(1) Polybutadiene rubber (Low cis (Lithium based catalyst)), natural rubber (Block (TSR-20)) were contacted with at least one additive such as carbon black, antioxidant, process aids in the banbury mixer at a speed in the range of 60-90 rpm for about 4-6 minutes to obtain a first mixture, wherein the dump temperature was in the range of 145-155℃ and the mooney viscosity of the first mixture as obtained was in the range of 90-120 MU.
(2) The first mixture as obtained in (1) was contacted with sulfur, 1,6-bis(N,N-dibenzylthiocarbamoyldithio)-hexane, N-tert-butyl-2-benzothiazyl sulfonamide, and cyclohexylthio phthalimide at a speed in the range of 40-60 rpm for about 2-3 minutes to obtain the rubber compound, wherein the dump temperature was in the range of 95-105℃ and the mooney viscosity of the rubber compound as obtained was in the range of 75-85 MU.
(3) The rubber compound as prepared in the banbury mixer was then sheeted out in 6mm at the end of the second step in the two-roll mill to obtain the abrasion gum strip rubber composition of the present disclosure.
[0061] The abrasion gum strip rubber composition as prepared above was subjected to various analyses of the physical and mechanical properties, wherein the composition was tested for understanding the effect of different ingredients on reversion index, retention of tensile strength and elongation at break.
EXAMPLE 2
[0062] The abrasion gum strip rubber composition as prepared in Example 1 was tested for reversion index, retention of tensile strength and elongation at break. Reversion index is a parameter that shows the percentage reversion from highest torque, attained by the compound (AGS rubber composition) in rheological analysis after 15 minutes

of reaching the highest torque. Retention of tensile strength and elongation at break were checked by testing the composition before and after the accelerated air ageing. Accelerated air ageing was done in cell type air oven with predefined temperature and predefined air flow rate.
(a) Reversion index of the composition
[0063] The reversion index property of the abrasion gum strip rubber composition was determined at 160°C from a rheo-graph. For getting a rheo-graph, 6.0 gram of rubber composition as prepared in above example 1, was tested in a moving die rheometer. The rubber composition was kept in between two dies of the moving die rheometer and the temperature was set at 160°C. After closing, dies moved at 0.5° arc in 1 direction for about 45 minutes. The high temperature of 160°C caused the vulcanization reaction to start in the rubber composition, due to which the rubber composition resisted moving die. This led to the creation of torque of the rubber composition. The reversion index as a percentage drop in compound torque after reaching its highest torque was calculated from the rheograph.
(b) Tensile strength and tensile strength retention
The tensile strength of the abrasion gum strip rubber composition of the present disclosure was tested as per the protocol provided in ASTM D412, Die C type. The retention of tensile strength was measured by first performing the accelerated air ageing at 100°C for about 2 days and then the abrasion gum strip rubber composition was tested as per the protocol provided in ASTM D412, Die C type. Percentage (%) retention in tensile strength was calculated by the following formula:
% retention in ~j
tensile strength I = (Tensile strength after accelerated ageing/Tensile strength of before ageing)* 100
(c) Elongation at Break and Elongation at Break Retention
[0064] Elongation at break of the abrasion gum strip rubber composition of the present disclosure was tested as per the protocol provided in ASTM D412, Die C type. Retention of Elongation at Break was measured by first performing the accelerated air

ageing at 100°C for about 2days and then the abrasion gum strip rubber composition was tested as per the protocol provided in ASTM D412, Die C type. Percentage retention in elongation at break was calculated by the following formula.
% retention in
, , L_ = (Elongation at break after accelerated ageing/elongation at break before ageing)* 100 elongation at break
RESULTS
[0065] The characteristics and results of the aforementioned properties are provided in Table 2 below. Table 2:

Properties Results
Reversion Index @ 160°C 2.5%
Tensile Strength 200 kg/cm2
Elongation at Break 330 %
Retention in Tensile strength after 100°C for 2 days 78%
Retention in Elongation at break after 100°C for 2 days 63%
[0066] Referring to Table 2, the percentage of reversion index of the abrasion gum
strip rubber composition calculated from the rheograph at 1600C, was found to have a
lowered reversion index, i.e. 2.5%.
[0067] Further, the tensile strength of the abrasion gum strip rubber composition was
found to be 200 kg/cm2. Additionally, the composition showed improved retention of
the tensile strength of 78% after 2 days at 1000C
[0068] Furthermore, the percentage of Elongation at Break of the abrasion gum strip
rubber composition was found out to be 330%, and retention in Elongation at break
after 100°C for 2 days was 63%. This shows that the rubber composition of the abrasion
gum strip shows improved ageing.

[0069] Table 3 shows the working ranges of the aforementioned properties. Table 3

Analytical Parameters Min Max
Reversion Index @ 160°C 1% 4%
Tensile Strength kg/cm2 190 220
Elongation at Break 300 450
Retention in Tensile strength after 100°C x 2 days 75% 85%
Retention in Elongation at break after 100°C x 2 days 50% 70%
[0070] Referring to Table 3, the abrasion gum strip rubber composition was found to have the percentage range of reversion index at 1600C between 1 to 4, percentage range of tensile strength between 190 to 220 kg/cm2, percentage range of retention in tensile strength between 75% to 85%, percentage of elongation at break after 2 days in 100°C ranged between 50% to 70%.
[0071] It can be inferred from Table 2 and 3 that the abrasion gum strip rubber composition of the present disclosure exhibits lowered reversion index as well as improved retention in tensile strength and improved elongation of break after ageing. This enables the abrasion gum strip rubber composition to remain free form cracks & cuts during tire service life.
EXAMPLE 3
NON-WORKING EXAMPLE
[0072] The present disclosure discloses the rubber composition prepared according
to the process as described in Example 1. The rubber composition of the present
example was prepared according to the formulation as provided in the below Table 4.
Table 4: Various components in parts by weight of a non-working abrasion gum strip
rubber composition

Category Components Parts by Weight

Poly Butadiene Rubber High Cis (96%) 50
Low cis (35-38%) 0
Natural Rubber Block (TSR-20) 50
Additive Carbon Black -Primary; BET Surface Area 78 ± 5 m2/g 78

Cure activator Zinc oxide 2.75

Stearic acid 2

Antioxidant N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylendiamine (6PPD) 0.75

Mixed aryl mixed aryl p-phenylene diamines (PPD) 0.0

2,2,4-trimethyl-l,2-dihydroquinoline (TQ) 1.0

Process aid Wax 0.75

PF Resin 2

Hydrocarbon resin 2

Naphthenic oil 10
Cross-linking agent Sulfur 2.8
Cure accelerator 1,6-bis(N,N-dibenzylthiocarbamoyld ithio)-hexane 0
Rubber accelerator N-tert-butyl-2-benzothiazyl sulfonamide (TBBS) 1.2
Retarder Cyclohexylthio phthalimide 0.3

[0073] The abrasion gum strip rubber composition as prepared above was subjected to various analyses, wherein the composition was tested for understanding the effect of different ingredients on reversion index, retention of tensile strength and elongation at break.
RESULTS
[0074] The prepared composition was then subjected to various analyses to obtain its
properties as explained in Example 2. The characteristics and the aforementioned
properties of the composition are shown in Table 5.
Table 5:

Properties Results
Reversion Index @ 160°C 15.5%
Tensile Strength 185 kg/cm2
Elongation at Break 290%
Retention in Tensile strength after 100°C for 2 days 57%
Retention in Elongation at break after 100°C for 2 days 38%
[0075] Referring to Table 5, the percentage of reversion index of the abrasion gum
strip rubber composition calculated from the rheograph at 1600C, was found to have a
reversion index, i.e. 15.5%.
[0076] Further, the tensile strength of the abrasion gum strip rubber composition was
found to be 185 kg/cm2 with the retention of the tensile strength of 57% after 2 days at
1000C.
[0077] Furthermore, the percentage of elongation at break of the abrasion gum strip rubber composition was found out to be 290%, and retention in elongation at break after 100°C for 2 days was 38%.
[0078] It can be inferred from Table 5 that due to the absence of cis-content butadiene rubber, the rubber composition showed a higher reversion index (15.5%), a lower

tensile strength & retention in tensile strength (185 kg/cm2, and 57%, respectively), and a lowered elongation at break (290%) and a decreased retention in elongation at break (38%). Also, the weight ratio of sulphur to TBBS weight ratio (2.3) was falling outside the disclosed range (0.4 - 1.5) of the present disclosure. Therefore, the rubber composition did not show relevant properties as exhibited by the abrasion gum strip rubber composition of the present disclosure. Therefore, this example is considered to be a non-working example.
[0079] Overall, it is important to have all the components of the abrasion gum strip of the present disclosure within their disclosed weight ranges in order to have improved properties such as reversion index, tensile strength and elongation at break. The absence of any of the components or even deviating from their disclosed weight ranges does not exhibit the desired effect.
Advantages of the present disclosure
The present disclosure discloses an abrasion gum strip rubber composition comprising: a) at least one polybutadiene rubber; b) 30 - 70 phr of at least one natural rubber; c) 1.0 - 1.5 phr of at least one cross-linking agent; d) 0.3 -1.0 phr of at least one cure accelerator; and e) 1.0 - 2.5 phr of at least one rubber accelerator, wherein the at least one polybutadiene rubber has a cis 1,4-bond content in the range of 35 - 38 wt. %, and the at least one cross-linking agent to the at least one rubber accelerator weight ratio is in the range of 0.4 - 1.5.The composition is found to have lowered reversion index and also exhibits improved retention in tensile strength and improved elongation of break after ageing. This enables the abrasion gum strip rubber composition to remain free form cracks & cuts during tire service life. The abrasion gum strip rubber composition of the present disclosure can be used in the tubeless tires or any tires to avoid the tires from cracking, and thereby stops the air to bleed out from the tires. Overall, the abrasion gum strip rubber composition will help in avoiding complete functional loss of the pneumatic tire.

I/We Claim:
1) An abrasion gum strip rubber composition comprising:
(a) 30 – 70 phr of at least one polybutadiene rubber;
(b) 30 – 70 phr of at least one natural rubber;
(c) 1.0 – 1.5 phr of at least one cross-linking agent;
(d) 0.3 -1.0 phr of at least one cure accelerator; and
(e) 1.0 - 2.5 phr of at least one rubber accelerator,
wherein the at least one polybutadiene rubber has cis 1,4-bond content in the range of 35 – 38 wt. %, and the at least one cross-linking agent to the at least one rubber accelerator weight ratio is in the range of 0.4 - 1.5.
2) The abrasion gum strip rubber composition as claimed in claim 1, wherein the at least one polybutadiene rubber is selected from the group consisting of lithium butadiene rubber (Li-BR), cobalt butadiene rubber (Co-BR), nickel-butadiene rubber (Ni-BR), neodymium butadiene rubber (Nd-BR), and combinations thereof.
3) The abrasion gum strip rubber composition as claimed in claim 1, wherein the at least one natural rubber is selected from is selected from the group consisting of ribbed smoked sheets, technically specified natural rubber, polyisoprene rubber, and combinations thereof.
4) The abrasion gum strip rubber composition as claimed in claim 1, wherein the at least one cross-linking agent is selected from the group consisting of sulphur, soluble sulphur, insoluble sulphur, and combinations thereof.
5) The abrasion gum strip rubber composition as claimed in claim 1, wherein the at least one rubber accelerator is selected from the group consisting of N-tert-butyl-2-benzothiazyl sulfonamide (TBBS), N-cyclohexyl -2- benzothiazole sulfonamide, N-oxydienthylene-2-benzothiazole sulfenamide, and combinations thereof.

6) The abrasion gum strip rubber composition as claimed in claim 1, wherein the composition further comprises at least one additive selected from the group consisting of 70 - 85 phr of carbon black, 1 - 8 phr of at least one cure activator, 0.5 - 9 phr of at least one antioxidant, 0 - 14 phr of at least one process aid, 0 - 0.5 phr of at least one retarder, and combinations thereof.
7) The abrasion gum strip rubber composition as claimed in claim 1, wherein the carbon black has a surface area in the range of 73 - 83 m2/g.
8) The abrasion gum strip rubber composition as claimed in claim 6, wherein the at least one cure activator is selected from the group consisting of zinc oxide, stearic acid, and combinations thereof; the at least one antioxidant is selected from the group consisting of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylendiamine (6PPD), mixed aryl p-phenylene diamines (PPD), 2,2,4-trimethyl-l,2-dihydroquinoline (TQ), and combinations thereof; at least one process aid is selected from the group consisting of phenol formaldehyde (PF) resin, wax, C5-30 hydrocarbon resin, naphthenic oil, and combinations thereof; the at least one retarder is N-cyclohexylthio-phthalimide.
9) The abrasion gum strip rubber composition as claimed in any one of the claims 1-6, wherein the composition has reversion index in the range of 1 - 4.0 % at a temperature of 160 ℃.
10) The abrasion gum strip rubber composition as claimed in any one of the claims 1-6, wherein the composition has tensile strength in the range of 187-220 kg/cm2.
11) The abrasion gum strip rubber composition as claimed in any one of the claims 1-6, wherein the composition has elongation to break percentage in a range of 300-450%.
12) A process for preparing the abrasion gum strip rubber composition as claimed in claim 1, the process comprising:

(a) contacting 30 – 70 phr of at least one polybutadiene rubber, 30 – 70 phr of at least one natural rubber; 1.5 – 1.0 phr of at least one cross-linking agent, 0.3 -1.0 phr of at least one cure accelerator, 1.0 - 2.5 phr of at least one rubber accelerator to obtain the abrasion gum strip rubber composition.
13) A process for preparing the abrasion gum strip rubber composition as claimed
in claim 6, the process comprising:
(a) contacting 30 – 70 phr of at least one polybutadiene rubber, 30 – 70 phr of at least one natural rubber; 1.5 – 1.0 phr of at least one cross-linking agent, 0.3 -1.0 phr of at least one cure accelerator, 1.0 - 2.5 phr of at least one rubber accelerator, 70 – 85 phr of carbon black, 1 – 8 phr of at least one cure activator, 0.5 – 9 phr of at least one antioxidant, 0 – 14 phr of at least one process aid, 0 – 0.5 phr of at least one retarder to obtain the abrasion gum strip rubber composition.
14) A tire comprising the abrasion gum strip rubber composition as claimed in
claim 1.