FIELD OF INVENTION:

The present invention relates to a sulphur vulcanizable rubber composite of novel composition. Particularly the present invention relates to a vehicle tyre made of rubber composition and process of preparation thereof. More particularly the invention relates to a novel rubber composition suitable for winter tyres

PRIOR ART:
It is highly desirable for winter tires to have good wet braking performance and good braking performance on snow and ice. It has traditionally been very difficult to improve simultaneously a tire's braking characteristics on wet surfaces and snow and ice surfaces. This is because a good wet braking tread formulation needs to provide a high energy dissipation at low temperatures between about -20°C and about 0°C at a frequency of 10 Hz. Such a high energy dissipation is related to a stiffening of the rubber tread at temperature's between -10°C and -40 °C, which negatively impacts braking on snow and ice. It would therefore be desirable to have a rubber composition for tires wherein the wet braking performance and braking on ice and snow are simultaneously improved. In winter tyres, the polymer combination is so chosen to meet these requirements.

In conventional winter tyres, a combination of elastomers such as Natural rubber (NR), Emulsion Styrene Butadiene Rubber (ESBR)/ Oil extended Emulsion Styrene Butadiene Rubber (OESBR), Solution SBR (SSBR) and Poly butadiene Rubber (BR) of suitable grades are used.

Since the availability of solution SBR (SSBR) is limited, there is a need for substitution of this component in the preparation of rubber compositions, especially that for tyres. This has been made possible in particular due to the discovery of a new rubber composition containing a suitably modified natural rubber which is capable of substituting a conventional SSBR (having a styrene content of 20 -30 % and medium to high vinyl content of 45 to 55 % and having Tg value in the range - 40 to -30°C) in such compositions.

In order to improve original low strength of SBR, reinforcing fillers are added in the compounds. High level of filling of their compounds require use of efficient softeners and processing additives. Degradation of SBR rubbers is lower than for NR, however presence of anti-degradants are essential. Sulphur cure system comprising sulphur and accelerators are used for vulcanization of rubber.

OBJECT OF INVENTION:

1. The main object of the present invention is to prepare a rubber composition.

2. Another object of the present invention is to utilize the rubber composition to prepare a vehicle tyre.

3. Yet another object of the present invention is to prepare a rubber composition for winter tyres, which demands mainly high wet and snow traction as well as low rolling resistance.

4. Yet another object of the present invention is to prepare vehicle tyre made of rubber composition with excellent wet and snow grip, low rolling resistance and also exhibiting reasonable good abrasion resistance.

SUMMARY OF THE INVENTION:-

The present invention relates to a sulphur vulcanizable rubber composition suitable for pneumatic tyre, more particularly for its ground contacting tread and vehicle tyre made of the said rubber composition and a process of preparation thereof. The rubber composition and/or vehicle tyre made of rubber composition comprises of natural rubber, epoxidised natural rubber (ENR) of suitable grade and further including emulsion SBR or oil extended emulsion SBR, Poly butadiene rubber (BR), fillers, process oil, anti-degradants, cure activators, curatives, silane coupling agents and other processing aids so as to meet the physical property requirements for the tyres particularly of the winter tyre compositions.

DESCRIPTION OF THE INVENTION :-

The present invention describes a new composition for winter tyres, which demands mainly high wet and snow traction as well as low rolling resistance. It is known that such tyre compositions especially those of tread compositions must conform to numerous technical demands which are frequently contradictory such as excellent wet and snow grip, low rolling resistance and at the same time reasonably good abrasion resistance. This could be achieved by the selection of suitable elastomer / elastomer combination, filler/filler combination and other general additives.
The invention relates to a rubber composition comprising of natural rubber , epoxidised natural rubber (ENR) of suitable grade, emulsion SBR or oil extended emulsion SBR, Poly butadiene rubber (BR), and further including fillers, process oil, anti-degradants, cure activators, curatives, silane coupling agents and other processing aids.

The terms compounds or compounded mean to refer to rubber compositions which have been compounded with appropriate compounding ingredients such as typically carbon black, oil, stearic acid, zinc oxide (Zno), anti-degradants, silica, silica couplers, curatives etc.

The term 'rubber' and 'elastomer' may be used interchangeably.
The invention relates to the composition as mentioned above and also a tyre using such a rubber composition and a method for producing the rubber composition and more specifically to a rubber composition for winter tyres suitable in high speed running vehicles.

The invention relates to a tyre having a component of such rubber compositions as described above.

In the present invention the SSBR in the conventional winter tyre composite is replaced by epoxidised natural rubber of suitable grade. Earlier it has been reported that selection of Solution SBR of suitable grade (with a styrene content of 20 -30 % and medium to high vinyl content of 45 -55 %) is ideal for winter tyre tread applications [Kautschuk Gummi Kunststoffe, Jul-Aug 2008, P.368, Jan - Feb 2009, P.35 & US 7,671,132 B1]. The said SSBR is having Tg in the range of -40 to -SOX. ENR of suitable grade (15 to 20 mole % epoxy content) having Tg in the range -40 to -30°C was developed and subsequently evaluated for the above applications. SSBR is partially/fully substituted for ESBR in the conventional tyre tread formulation for achieving low hysteresis and better wet and snow traction. In the present invention in such composites when SSBR was replaced with ENR of suitable grade, it was revealed surprisingly that technological properties relevant for the said application for the composites containing ENR was at par with those containing SSBR.

The other elastomers used are natural rubber(NR), polybutadiene rubber (BR), and emulsion SBR. BR used is a cis 1,4-polybutadiene rubber. It is made by solution polymerization of 1,3 -butadiene. BR is characterized by having at least 90 percent cis 1,4 content and a glass transition temperature (Tg) in the range from about - 95 °C to about-105 °C.

The second important requirement for the said application is the choice of filler. Precipitated silica is the most preferred filler in such application, as it can impart low rolling resistance, high wet and snow grip and fairly good abrasion resistance. A lesser quantity of carbon black compared to silica is also added due to its effective reinforcement in hydrocarbon rubbers and its ability to dissipate static electricity.

With the increase in the speed of vehicle there is a need to improve the high speed durability of the tyres and also to improve the gripping property of the tyres on the road surface as an essential safety measure.

As such it is now a known practice to compound silica alongwith or instead of carbon black. As such in the tyre composition of the present invention, to overcome the drawbacks of conventional rubber tyres, the reinforcing agents carbon black and silica may also be compounded in the rubber composition. The filler is not particularly limited but silica and/or carbon black is preferable. The natural rubber referred herein can be any natural rubber that is commonly used in rubber composition for manufacturing of tyres and is not particularly limited.

Unlike carbon black, compounding of silica in hydrocarbon rubbers causes dispersion problems. Though commercial high dispersible silica (such as 7000 GR) is now available, even further improvement could be achieved with the use of silica process aids (such as VP 1454 / HT 254 of Struktol , USA) and hence is used in tyre formulations.

In addition to these, Silane coupling agent is added to the composition to enhance the silica filler - polymer interaction resulting in effective reinforcement. It is used in silica filled rubbers as coupling agent. Typical commercially used silanes are Bis- (tri ethoxysilylpropyl) tetra sulphide (Si 69 / TESPT ) and Bis- (tri ethoxysilylpropyl) poly sulphide (Si 266 ). Commercial silanes are also available in masterbatch form, incorporated in fillers such as carbon black (eg. X50S).

Anti-degradants are added to the composition to protect the rubber composition from environmental degradations. Typical antidegradants used are N- (1,3 dimethylbutyl) -N'-phenyl - p- Phenylenediamine (6PPD) and N,N' - Diphenyl - p - Phenylenediamine (DPPD). Waxes (such as MC wax) are also incorporated to protect the rubber from degradation.
Cure activators are added to the composition to activate the sulphur vulcanization of rubbers. Typical cure activators used are Zinc oxide and/or Stearic acid.

Conventional process oils consisting of mild extraction solvent (MES) (free from poly aromatic hydrocarbons - PAH), process aids and curatives are also used for the design of the winter tyre tread formulations. Peptizers and silica dispersion modifier are used as processing aids. Conventional tyre curatives are sulphur and accelarators. Typical accelarators used are N-Cyclohexyl - 2 - benzothiazyl sulfenamide (CBS) and Diphenyl guanidine (DPG). The accelerators used for the vulcanization need not particularly be limited to those mentioned.

In one of the preferred embodiment, the invention shall describe a sulphur vulcanizable rubber composition suitable for tyres and particularly for winter tyres comprising of natural rubber. Emulsion SBR, Polybutadiene Rubber and epoxidised natural rubber (ENR), wherein ENR is characterized having epoxy content in the range of 15 to 20 mole % and having a Tg in the range of -40 to -30°C.

As per the invention the rubber composition further includes reinforcing filler consisting of at least one or more filler, such as precipitated silica in the range of 40 to 100 phr and more preferably 60 to 80 phr, and/or Carbon black in the range of 10 to 25 phr.

According to the invention the rubber composition further includes process oil consisting of MES (Mild extraction solvent) in the range of 10 to 30 phr. The rubber composition of the present invention further includes anti-degradants / protectants such as 6PPD in the range of 0.5 to 3 phr, and/or DPPD in the range of 0.5 to 3 phr, and/or Wax in the range of 0.5 to 3 phr.
The rubber composition further includes cure activators such as Zinc oxide in the range of 1 to 5 phr, and/or Stearic acid in the range of 0.5 to 3 phr, also includes curatives such as Sulphur in the range of 0.2 to 3 phr, and/or Sulphenamide type accelerator in the range of 0.1 to 2 phr, and/or Guanidine type accelerator in the range of 0.1 to 2.5 phr. The said composition of the present invention also includes additional processing aids such as Peptiser in the range of 0.01 to 0.03 phr, and/or Silica dispersion modifier in the range of 0.5 to 3 phr and silane coupling agents (such as TESPT, Si266 etc.) in the range of 6 to 12% of the silica content.

In another preferred embodiment the invention discloses a process of preparing the rubber composition comprising of mixing suitable grades of NR, Emulsion SBR, Poly butadiene Rubber and ENR, wherein ENR is characterized having epoxy content in the range of 15 to 20 mole % and having a Tg in the range of -40 to -30°C.

The process further comprises of adding reinforcing filler consisting of at least one or more filler, such as precipitated silica in the range of 40 to 100 phr and more preferably 60 to 80 phr, and/or Carbon black in the range of 10 to 25 phr.

The process further includes the step of adding process oil consisting of MES (Mild extraction solvent) in the range of 10 to 30 phr, anti-degradants / protectants such as 6PPD in the range of 0.5 to 3 phr, and/or DPPD in the range of 0.5 to 3 phr, and/or Wax in the range of 0.5 to 3 phr, cure activators such as Zinc oxide in the range of 1 to 5 phr, and/or Stearic acid in the range of 0.5 to 3 phr, curatives such as Sulphur in the range of 0.2 to 3 phr, and/or Sulphenamide type accelerator in the range of 0.1 to 2 phr, and/or Guanidine type accelerator in the range of 0.1 to 2.5 phr, silane coupling agents (such as TESPT, Si266 etc.) in the range of 6 to 12% of the silica content.
The said process further includes the step of adding additional processing aids such as Peptiser in the range of 0.01 to 0.03 phr, and/or Silica dispersion modifier in the range of 0.5 to 3 phr.

In another preferred embodiment the present invention relates to a vehicle tyre made of rubber composition comprising of natural rubber. Emulsion SBR, Polybutadiene Rubber and epoxidised natural rubber (ENR), wherein ENR is characterized having epoxy content in the range of 15 to 20 mole % and having a Tg in the range of -40 to -30°C.

As per the invention the composition further includes reinforcing filler consisting of at least one or more filler, such as precipitated silica in the range of 40 to 100 phr and more preferably 60 to 80 phr, and/or Carbon black in the range of 10 to 25 phr.

According to the invention the vehicle tyre made of rubber composition further includes process oil consisting of MES (Mild extraction solvent) in the range of 10 to 30 phr. The composition further includes anti-degradants / protectants such as 6PPD in the range of 0.5 to 3 phr, and/or DPPD in the range of 0.5 to 3 phr, and/or Wax in the range of 0.5 to 3 phr.
The vehicle tyre made of rubber composition further includes cure activators such as Zinc oxide in the range of 1 to 5 phr, and/or Stearic acid in the range of 0.5 to 3 phr, also includes curatives such as Sulphur in the range of 0.2 to 3 phr, and/or Sulphenamide type accelerator in the range of 0.1 to 2 phr, and/or Guanidine type accelerator in the range of 0.1 to 2.5 phr.
The said composition also includes additional processing aids such as Peptiser in the range of 0.01 to 0.03 phr, and/or Silica dispersion modifier in the range of 0.5 to 3 phr and silane coupling agents (such as TESPT, Si266 etc.) in the range of 6 to 12% of the silica content.

In another preferred embodiment the invention explains a process of preparing vehicle tyre made of rubber composition comprising of mixing suitable grades of NR, Emulsion SBR, Poly butadiene Rubber and ENR, wherein ENR is characterized having epoxy content in the range of 15 to 20 mole % and having a Tg in the range of -40 to -30°C.
The process further comprises of adding reinforcing filler consisting of at least one or more filler, such as precipitated silica in the range of 40 to 100 phr and more preferably 60 to 80 phr, and/or Carbon black in the range of 10 to 25 phr.

The process further includes the step of adding process oil consisting of MES (Mild extraction solvent) in the range of 10 to 30 phr, anti-degradants / protectants such as 6PPD in the range of 0.5 to 3 phr, and/or DPPD in the range of 0.5 to 3 phr, and/or Wax in the range of 0.5 to 3 phr, cure activators such as Zinc oxide in the range of 1 to 5 phr, and/or Stearic acid in the range of 0.5 to 3 phr, curatives such as Sulphur in the range of 0.2 to 3 phr, and/or Sulphenamide type accelerator in the range of 0.1 to 2 phr, and/or Guanidine type accelerator in the range of 0,1 to 2.5 phr, silane coupling agents (such as TESPT, Si266 etc.) in the range of 6 to 12% of the silica content.
The said process further includes the step of adding additional processing aids such as Peptiser in the range of 0.01 to 0.03 phr, and/or Silica dispersion modifier in the range of 0.5 to 3 phr.

Typical experimental composites, which embodiments the said finding is given in Table 1. The composites are marked as control (conventional) and novel /experimental (E1 and E2). Properties of the compositions that are given in Tables 2, 3, 4, 5, 6, 7, 8 and 9 is only illustrative and is not limiting the specification and covers many novel aspects of the invention, as will be understood by the skilled persons in the art.

The first aspect of the invention is the discovery of a composition usable for manufacturing of tyres mounted in high speed vehicles.

The second aspect of the invention is a discovery of a composition usable for semi-finished products, components intended for use in such referred tyres.
Tyres and these semi-finished products themselves when they comprise the said novel composition is the third aspect and the fourth aspect of the invention respectively.

However it is to be noted that the natural rubber may also be replaced by any other rubbers such as butadiene rubber (BR), isoprene rubber (IR), styrene- butadiene rubber (SBR) etc. Any of them can be selected or two or more kinds can be used together. However of all of these, natural rubber is the most preferred.

The process of preparing the composition of the natural rubber with the epoxidised natural rubber is not particularly limited. In the process of preparing the rubber compound, it is preferable that natural rubber be mixed with epoxidised natural rubber in a single step simultaneously.
A commonly used softening agent such as a process oil is preferably compounded to the rubber composition.

While the mechanism may not be fully understood an important aspects of the invention is for the inclusion of the epoxidised natural rubber of suitable grade in the preparation of the rubber composition of the invention, characterized in the epoxidised natural rubber possessing epoxy content in the range of 15 to 20 mole % and also having a Tg in the range -40 to -30°C.
While certain embodiments, tables and descriptions have been included for the purpose of illustrating the invention it will be apparent to those skilled in the art that vahous changes and modifications may be made herein without departing from the spirit or scope of the invention.

As described above, in addition to the natural rubber and epoxidised natural rubber of suitable grade, the rubber composition may be compounded selectively with known additives used in the rubber industries, tyre industries such as additional fillers, vulcanizing agents etc., within the scope not conflicting or hindering the object of the invention. All of the additives are generally known and commercially available additives.

The invention has been successful in replacing solution SBR with the epoxidised natural rubber of suitable grade having epoxy content in the range of 15 to 20 mole % and also having a Tg in the range -40 to -30°C in the rubber composition required for making vehicle tyres.
As described above, the present invention relates to a epoxidised natural rubber of suitable grade and a novel composition comprising the epoxidised rubber of said grade and further to a process for preparation of products such as tyres using the novel composition. It has been found that substitution of SSBR with epoxidised natural rubber of suitable grade surprisingly yield considerably better properties than in known conventional rubber compositions.

The quantity ratio of the components of the natural rubber and the epoxidised natural rubber will vary within wide limits according to the property profile demanded in the composition according to the invention and is not limited by the description disclosed herein and the illustrations made in tables.

TEST RESULT

Formulation Table 1
Ingrediants Control I El [ E2
NR 20.00 20.00 20.00
Peptizer 0.02 0.02 0.02
SSBR 37.5% oil, 25 S - 50V 27.50 0.00 0.00
SBR 1712 (Oil extended) 55.00 55.00 55.00
ENR 10 (epoxy 10 mole %) 0.00 20.00 0.00
ENR 17.5 (epoxy 17.5 mole %) 0.00 0.00 20.00
BR 20.00 20.00 20.00
Silica (7000 GR) 65.00 65.00 65.00
Carbon black (N 234 ) 15.00 15.00 15.00
X 50S (50% Active Content) 10.00 10.00 10.00
Process oil (free from PAH) 10.00 17.50 17.50
Stearic Acid Z50 Z50 2.50
Zno 3.00 3.00 3.00
MC wax 2.00 2.00 2.00
6 PPD 2.00 2.00 2.00
DPPD 0.50 0.50 0.50
VP 1454 ZOO ZOO 2.00
DPG 2.00 1.50 1.50
CBS 120 1.20 1.20
Soluble sulphur 2.25 2.25 2.25
Final 239.97 239.47 239.47
Table 2

Control El E2 ~
ML (1+1.5) @ 135°C 43.43 41.06 42.11
MS @ 135°C, t5(min) 7.62 9.17 10.75~
Table 3
Control El E2
ML (Ib-in) 5.07 5.03 5.29
MH (Ib-in) 34.31 35.25 35.29
MH-ML (Ib-in) 29.24 30.22 30.00
TS1 (min) 2.87 3.17 3.33
TS2 (min) 3.40 3.82 4.02
To 10 (min) 3.68 4.18 4.38
To 15 (min) 3.98 4.52 4.73
To 25 (min) 4.37 4.93 5.15
To 40 (min) 4.73 5.38 5.60
To 50 (min) 5.00 5.70 5.95
To 90 (min) 9.00 9.67 10.20

Table 4

Control El E2
Avg X (CB Dispersion) 8,9 8,3 8.4
Avg. Y (Aggre. Dispersion) 9,9 9,8 9.8
Specific gravity 1.191 1.194 1.196

Table 5

Physical Properties (cured at 160°C / ( 2Tc 90)
Control El E2
M 100 (Mpa) 2.85 2.71 2.69
M 200 (Mpa) 7.08 6.72 6.60
M 300 (Mpa) 11.76 11.23 11.13
TS (Mpa) 17.88 18.20 18.62
EB (%) 437 458 467
Hardness (Shore A) 70 69 69
Tear Strength (N/mm) 46.5 50.4 52.0 ~DIN Abrasion loss (mm1) I 98 I 92 I 93
HBU at base (°C) 29.2 28.6 28.6
HBU at centre (°C) 80.6 80.3 80.3

Table 6

Dynamic (Viscoelastic) properties 10Hz/0.25% Strain)
Control E1 E2
Storage Mod. (E') @ 60°C (Mpa) 25.5 24.3 26.9
Loss Mod. (E") @ 60°C (Mpa) 3.54 3.58 4.03
Loss Compliance @ 60°C (Mpa'1) 5.32x10madam 5.94x101 5.47x101
Tandelta (E"/ E') @ 60°C 0.139 0.147 0.150
Tandelta (E'V E') @ 25°C 0.187 0.190 0.194
Tandelta (E'V E') @ 0°C 0.234 0.219 0.226
Tandelta (E'V E') @ -25°C 0.430 0.337 0.361
Glass Tansition @ Tandelta Peak -35.9 -39.1 -34.9
Temp °C

Table 7

De-Mattia Cut Growth Properties
Cut Length in mm at Control El E2 ~
1.5 Kc 3.39 3.57 3.46
5_Kc 5.65 6.91 6.89
10 Kc 7.92 9.98 9.91
25 Kc 16.34 17.93 17.41

Table 8

De-Mattia Cut Initiation Properties
~ Control El E2
Pin Hole generation (Kc) 110 95 100

Table 9

Physical Properties (Aged at 100 °C / 48 hrs)
Control El E2
M100 (Mpa), Unaged 2.85 2.71 2.69
M100 (Mpa), Aged 4144 428 4.28
Retention (%) 156 158 159
M 200 (Mpa), Unaged 7.08 6.72 6.60
11200 (Mpa), Aged 10.52 10.19 10.14
I Retention (%) 149 152 154
M 300 (Mpa), Unaged 11.76 11.23 11.13
M 300 (Mpa), Aged 16.07 15.73 15.75
Retention (%) 137 140 142
TS (Mpa), Unaged 17.88 18.20 18.62
TS (Mpa). Aged 17.03 16.73 16.63
Retention (%) 95 92 89
EB (%), Unaged 437 458 467
EB (%), Aged 320 321 318
Retention (%) 73 70 68
Hardness (Shore A) Unaged 70 69 69
Hardness (Shore A) Aged 73 72 72
Change ( + 3) ( + 3) ( + 3)
Tear Strength (N/mm) Unaged 46.5 50.4 52.0
Tear Strength (N/mm) Aged 446 507 47
Retention (%) 96 101 |90

WE CLAIM :-

1. A sulphur vulcanizable rubber composition suitable for tyres and particularly for winter tyres comprising :

a. natural rubber
b. Emulsion SBR
c. Polybutadiene Rubber and
d. epoxidised natural rubber (ENR), characterized having epoxy content in the range of 15 to 20 mole % and having a Tg in the range of -40 to - 30°C.

2. The rubber composition as claimed in claim 1, further including a reinforcing filler consisting of at least one or more filler, consisting of

a. precipitated silica in the range of 40 to 100 phr and more preferably 60 to 80 phr, and/or
b. Carbon black in the range of 10 to 25 phr

3. The rubber composition as claimed in claim 1, further including process oil consisting of MES (Mild extraction solvent) in the range of 10 to 30 phr.

4. The rubber composition as claimed in claim 1, further including anti-degradants / protectants such as

a. 6PPD in the range of 0.5 to 3 phr, and/or
b. DPPD in the range of 0.5 to 3 phr, and/or
c. Wax in the range of 0.5 to 3 phr
5. The rubber composition as claimed in claim 1, further including cure activators such as

a. Zinc oxide in the range of 1 to 5 phr, and/or
b. Stearic acid in the range of 0.5 to 3 phr

6. The rubber composition as claimed in claim 1, further including curatives such as

a. Sulphur in the range of 0.2 to 3 phr, and/or
b. Sulphenamide type accelerator in the range of 0.1 to 2 phr, and/or
c. Guanidine type accelerator in the range of 0.1 to 2.5 phr

7. The rubber composition as claimed in claim 1, further including additional processing aids such as

a. Peptiser in the range of 0.01 to 0.03 phr, and/or
b. Silica dispersion modifier in the range of 0.5 to 3 phr

8. The rubber composition as claimed in claim 1, further including silane coupling agents (such as TESPT, Si266 etc.) in the range of 6 to 12% of the silica content.

9. A process of preparing rubber composition comprising of mixing of suitable grades of NR, Emulsion SBR, Poly butadiene Rubber and ENR, wherein ENR is characterized having epoxy content in the range of 15 to 20 mole % and having a Tg in the range of -40 to -30°C.

10. The process as claimed in claim 9, further including the step of adding reinforcing filler consisting of at least one or more filler, consisting of

a. precipitated silica in the range of 40 to 100 phr and more preferably 60 to 80 phr, and/or
b. Carbon black in the range of 10 to 25 phr

11. The process as claimed in claim 9, further including the step of adding process oil consisting of MES (Mild extraction solvent) in the range of 10 to 30 phr.

12. The process as claimed in claim 9, further including the step of adding anti- degradants / protectants such as

a. 6PPD in the range of 0.5 to 3 phr, and/or
b. DPPD in the range of 0.5 to 3 phr, and/or
c. Wax in the range of 0.5 to 3 phr

13. The process as claimed in claim 9, further including the step of adding cure activators such as

a. Zinc oxide in the range of 1 to 5 phr, and/or
b. Stearic acid in the range of 0.5 to 3 phr

14. The process as claimed in claim 9, further including the step of adding curatives such as

a. Sulphur in the range of 0.2 to 3 phr, and/or
b. Sulphenamide type accelerator in the range of 0.1 to 2 phr, and/or
c. Guanidine type accelerator in the range of 0.1 to 2.5 phr

15. The process as claimed in claim 9, further including the step of adding additional processing aids such as

a. Peptiser in the range of 0.01 to 0.03 phr, and/or
b. Silica dispersion modifier in the range of 0.5 to 3 phr

16. The process as claimed in claim 9, further including the step of adding silane coupling agents (such as TESPT, Si266 etc.) in the range of 6 to 12% of the silica content.

17. A vehicle tyre made of rubber composition comprising of:

a. natural rubber
b. Emulsion SBR
c. Polybutadiene Rubber and
d. epoxidised natural rubber (ENR), characterized having epoxy content in the range of 15 to 20 mole % and having a Tg in the range of -40 to - 30°C.

18. The vehicle tyre made of rubber composition as claimed in claim 17, comprising of:

a. precipitated silica in the range of 40 to 100 phr and more preferably 60 to 80 phr, and/or
b. Carbon black in the range of 10 to 25 phr

19. The vehicle tyre made of rubber composition as claimed in claim 17, comprising further of process oil consisting of MES (Mild extraction solvent) in the range of 10 to 30 phr.

20. The vehicle tyre made of rubber composition as claimed in claim 17, comprising further of anti-degradants / protectants such as

a. 6PPD in the range of 0.5 to 3 phr, and/or
b. DPPD in the range of 0.5 to 3 phr, and/or
c. Wax in the range of 0.5 to 3 phr

21. The vehicle tyre made of rubber composition as claimed in claim 17, comprising further of cure activators such as

a. Zinc oxide in the range of 1 to 5 phr, and/or
b. Stearic acid in the range of 0.5 to 3 phr

22. The vehicle tyre made of rubber composition as claimed in claim 17, comprising further of curatives such as

a. Sulphur in the range of 0.2 to 3 phr, and/or
b. Sulphenamide type accelerator in the range of 0.1 to 2 phr, and/or
c. Guanidine type accelerator in the range of 0.1 to 2.5 phr

23. The vehicle tyre made of rubber composition as claimed in claim 17, comprising further of additional processing aids such as

a. Peptiser in the range of 0.01 to 0.03 phr, and/or
b. Silica dispersion modifier in the range of 0.5 to 3 phr

24. The vehicle tyre made of rubber composition as claimed in claim 17, comprising of silane coupling agents (such as TESPT, Si266 etc.) in the range of 6 to 12% of the silica content.
25. A process of preparing a vehicle tire made of rubber composition, the said process comprising of mixing of suitable grades of NR, Emulsion SBR Polybutadiene Rubber and ENR, wherein ENR is characterized having epoxy content in the range of 15 to 20 mole % and having a Tg in the range of -40 to - 30°C.

26. The process as claimed in claim 25, further including the step of adding reinforcing filler consisting of at least one or more filler, consisting of

a. precipitated silica in the range of 40 to 100 phr and more preferably 60 to 80 phr, and/or
b. Carbon black in the range of 10 to 25 phr

27. The process as claimed in claim 25, further including the step of adding process oil consisting of MES (Mild extraction solvent) in the range of 10 to 30 phr.

28. The process as claimed in claim 25, further including the step of adding anti- degradants / protectants such as

a. 6PPD in the range of 0.5 to 3 phr, and/or
b. DPPD in the range of 0.5 to 3 phr, and/or
c. Wax in the range of 0.5 to 3 phr

29. The process as claimed in claim 25, further including the step of adding cure activators such as

a. Zinc oxide in the range of 1 to 5 phr, and/or
b. Stearic acid in the range of 0.5 to 3 phr

30. The process as claimed in claim 25, further including the step of adding curatives such as

a. Sulphur in the range of 0.2 to 3 phr, and/or
b. Sulphenamide type accelerator in the range of 0.1 to 2 phr, and/or
c. Guanidine type accelerator in the range of 0.1 to 2.5 phr

31. The process as claimed in claim 25, further including the step of adding additional processing aids such as
a. Peptiser in the range of 0.01 to 0.03 phr, and/or
b. Silica dispersion modifier in the range of 0.5 to 3 phr

32. The process as claimed in claim 25, further including the step of adding silane coupling agents (such as TESPT, Si266 etc.) in the range of 6 to 12% of the silica content.