DESC:FIELD OF THE INVENTION
The present invention relates to the field of tires. More particularly, the present invention relates to the tire tread compound. The present invention relates to the tire tread compound that offers low rolling resistance and high rubber elasticity using naturally occurring Fuller’s earth nanoclay as the nano-filler.

BACKGROUND OF THE INVENTION
In recent years, tires for automobiles have required performances, such as the controllability in driving, low rolling resistance. To satisfy these requirements, tire tread compounds having low rolling resistance are provided by using rubber compositions obtained by missing silica with styrene butadiene rubber of high styrene unit content for tire treads.

US7220794 related to a rubber composition for tire treads which significantly improves the wet skid performance of the tire, which comprises diene rubber containing 35% styrene butadiene rubber, clay, silica and carbon black. Clay is 30 parts, silica is 20 parts and carbon black is 25 parts.

The addition of fillers to polymers is a common industrial practice. Its purpose is generally two fold; to reduce the overall cost of the composite while concurrently bringing about improvement in, for example, mechanical properties such as wear, hardness, tensile modulus, tear etc. Common inorganic nanometer or “nano-scale” fillers possess extremely high surface area with high surface energy. Formation of organic inorganic nanocomposites based on clays or layered silicate such as montmorillonite is known.

US7750070 relates to a process of preparing a nanocomposite comprised of an elastomer with partially exfoliated, intercalated water swellable clay. The rubber composition containing such nanocomposite, when used will replace a portion of the normally used carbon black or silica reinforcement. This is particularly adaptable for use as a component for a tire, particularly a tire tread applications. It uses VPSBR terpolymer as the base polymer.

US7601772 and US7572855 use nanoclay in a polymer formulation to form a nano-composite. The nano-composite is practically useful in formulation compositions such as rubber and tire products with improved and well – balanced properties including gas permeability, cure properties, and / or mechanical properties etc. These patents use treated organo-clay in the composition.

The present invention aims to provide excellent low rolling resistance using naturally occurring unmodified Fuller’s Earth nanoclay as the nanofiller.

OBJECT OF THE PRESENT INVENTION
It is primary object of the present invention to provide motor cycle tire tread compound, using unmodified Fuller’s Earth nanoclay based nanocomposite, offering low rolling resistance.

It is another object of the present invention to provide motor cycle tire tread compound, using un-modified Fuller’s Earth nanoclay based nanocomposite, offering high rubber elasticity.

It is another object of the present invention to provide a partial replacement for carbon black using unmodified Fuller’s Earth nanoclay for motor cycle tire tread compound.

It is another object of the present invention to provide cost effective and environmental friendly motor cycle tire tread compound using un-modified Fuller’s Earth nanoclay.

SUMMARY OF THE INVENTION
One or more of the problems of the conventional prior arts may be overcome by various embodiments of the present invention.

It is a primary aspect of the present invention to provide a rubber nanocomposite composition for motor cycle tyre tread, comprising of:
one or more rubbers – 100 phr;
nanofillers – 1 – 25 phr;
reinforcing fillers – 30 – 85 phr;
coupling agent – 0 – 2.5 phr;
accelerators – 0.25 – 4 phr;
vulcanization agent – 1 – 5 phr;
cure activators – 1- 8 phr;
anti-degradants – 0.5 – 8.5 phr; and
process aid – 5 – 20 phr,
wherein the nanofiller is unmodified Fuller’s earth nanoclay having
a length between 1-3000 nanometer; diameter of 1-30 nanometer
and the aspect ratio of 5-50.

It is another aspect of the present invention to provide a rubber nanocomposite composition for tyre tread, wherein the one or more rubbers are selected from solution based styrene butadiene rubber, natural rubber, poly butadiene rubber and combinations thereof.

It is another aspect of the present invention to provide a rubber nanocomposite composition for tyre tread, wherein the reinforcing fillers are selected from carbon black and silica preferably in a weight ratio of 30 – 60 : 0 – 25 phr.

It is another aspect of the present invention to provide a rubber nanocomposite composition for tyre tread, wherein the cure activators are selected from stearic acid, zinc oxide and combinations thereof preferably in a weight ratio of 1-3: 2-5 phr.

It is another aspect of the present invention to provide a rubber nanocomposite composition for tyre tread, wherein the anti-degradants are selected from Microcrystalline wax, (1,3-Dimethylbutyl)- N’-phenyl-p-phenylenediamine (6PPD), (2,2,4-trimethyl-1,2-dihydroquinoline) (TMQ) and combinations thereof, preferably in a weight ratio of 1-3:1-3:0.5 – 2.5 phr.

It is another aspect of the present invention to provide a rubber nanocomposite composition for tyre tread, wherein the vulcanization agent is sulphur.

It is another aspect of the present invention to provide a rubber nanocomposite composition for tyre tread, wherein the cure accelerators are selected from CBS, DPG and combinations thereof, preferably in a weight ratio of 0.5 - 2: 0.25 – 2 phr.

It is another aspect of the present invention to provide a rubber nanocomposite composition for tyre tread, wherein the process aid is TDAE oil.

It is another aspect of the present invention to provide a rubber nanocomposite composition for tyre tread, wherein the coupling agent is silane (Si69).

It is another aspect of the present invention to provide a method of preparation of rubber nanocomposite composition for tyre tread, comprising of steps:
Master batch mixing by:
masticating of selected rubbers;
half loading (50%) of reinforcing filler carbon black, unmodified fuller’s earth nanoclay, silane (Si69) are added and mixed;
adding of remaining 50% of carbon black, unmodified fuller’s earth nanoclay, silane (Si69) along with process aid TDAE oil, microcrystalline wax, stearic acid, (2,2,4-trimethyl-1,2-dihydroquinoline) (TMQ) and mixing;
silanization at 10 – 30 rpm;
sweeping down the orifice and mixing the master batch rubber compound at 50 – 70 rpm at a temperature range of 140ºC to 150ºC; and
dumping at the temperature range of 155ºC to 165ºC,
wherein the rotational speed for mixing is maintained between 50 to 70 rpm and the temperature is maintained between 50°C to 70°C,
Repass mixing sequence:
mixing of master batch compound at 50 - 70 rpm at a temperature
range between 50ºC and 70ºC;
warming of the master batch and mixing with chemicals zinc oxide
and (1,3-Dimethylbutyl)- N’-phenyl-p-phenylenediamine (6PPD); and
dumping of the compound and further mixing,
Final batch preparation by
mixing of master batch and the curatives sulphur, (N-cyclohexyl-2-
benzothiazolesulfenamide) and Diphenyl Guanidine (DPG);
dumping at a temperature range between 80ºC and 110ºC; and
sheet out the compound.

DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to a rubber nanocomposite based on solution based styrene butadiene rubber in combination with or without other polymers like natural rubber and poly butadiene rubber, unmodified Fuller’s Earth nanoclay as nanofiller in combination with carbon black and with or without silica. The developed nanocomposite offers excellent low rolling resistance and high rubber elasticity. Unmodified fullers earth in rubber nanocomposite provides higher rolling resistance as the elemental composition of unmodified fuller’s earth nanoclay contains greater than 20 weight% of Si element.

According to primary aspect of the present invention the rubber nanocomposite formulation comprises of one or more rubbers, unmodified fuller’s earth nanoclay, and reinforcing filler selected from carbon black and silica.

According to the present invention the formulation of rubber compound further comprises of silane as coupling agent; (N-cyclohexyl-2-benzothiazolesulfenamide) and Diphenyl Guanidine as accelerators; sulphur as vulcanization agent; stearic acid, zinc oxide and combinations thereof as cure activators; Microcrystalline wax, (1,3-Dimethylbutyl)-N’-phenyl-p-phenylenediamine, (2,2,4-trimethyl-1,2-dihydroquinoline) and combinations thereof as anti-degradants and TDAE oil as processing aid.

Table 1 Shows detail of ingredients according to the present invention:
Ingredients Control, phr Formulation related to invention, phr Control, phr Formulation related to invention, phr
SSBR SLR563 70-95 70-95
SSBR HPR 355 70-95 70-95
PBR 5-30 5-30 5-30 5-30
N330 30-60 30-60 30-60 30-60
Silica 0-25 0-25 0-25 0-25
Fuller’s Earth 1-25 1-25
Si69 0-2.5 0-2.5 0-2.5 0-2.5
TDAE Oil 5-20 5-20 5-20 5-20
Stearic Acid 1-3 1-3 1-3 1-3
Zinc Oxide 2-5 2-5 2-5 2-5
MC Wax 1-3 1-3 1-3 1-3
6 PPD 1-3 1-3 1-3 1-3
TMQ 0.5-2.5 0.5-2.5 0.5-2.5 0.5-2.5
Sulphur 1-5 1-5 1-5 1-5
CBS 0.5-2 0.5-2 0.5-2 0.5-2
DPG 0.25-2 0.25-2 0.25-2 0.25-2

The present invention describes a method of preparation of the rubber composition for tyre tread nano composite with solution based styrene butadiene rubber, in combination with or without other polymers like natural rubber and poly butdiene rubber; a reinforcing filler comprising of carbon black; and an unmodified Fuller’s Earth nano clay as a nano filler.

For the purpose of exemplification the rubber composition according to the present invention is prepared by a thermo mechanical process in a banbury mixer.

A. Master Batch Preparation
Preparation of master batch has been performed with the rotor speed of the mixer between 50 to 70 rpm and with the head temperature of the banbury maintained between 50°C to 70°C. The method of preparation of Master Batch includes following steps:
1. The mixing chamber is initially loaded with solution based styrene butadiene Rubber (SSBR) and poly butadiene rubber (PBR) and masticated for 15-60 seconds.
2. Half the loading (50%) of reinforcing filler carbon black, unmodified Fuller’s Earth nanoclay, silane Si69 are added and allowed to mix for 20-60 seconds.
3. The remaining half of the carbon black, unmodified Fuller’s Earth nanoclay, silane si69 along with TDAE oil, MC Wax, stearic acid, TMQ are loaded in the mixer and mixed for 20 – 60 seconds.
4. The silanization process is then carried out. The rotor speed is reduced to a range of 10-30 rpm and this process takes place for 30-90 seconds.
5. Sweeping down the chemicals in the orifice and allowed to mix further. The rotor speed is now increased back to the initial range of 50-70 rpm. The process is carried out until temperature reaches a range of 140°C-150°C.
6. Finally the mixed compound is dumped at a temperature range of 155°C-165°C.

B. Repass Mixing Sequence
The repass mixing process has been performed with the rotation speed of the rotor between 50 to 70 rpm and with the head temperature of the banbury maintained between 50°C to 70°C.The repass mixing sequence includes following steps:
1. The mixed Master Batch compound is warmed for 15-45 seconds in the mixer and chemicals like zinc oxide and 6PPD are added.. The mixing process is carried out for 30-120 seconds and dumped.
2. The repass 1 compound is again loaded in the mixer for the second repass mixing process. The compound is loaded in the mixer and mixed for 30-120 seconds.

C. Final Batch Preparation
Mixing chamber is loaded with the master batch and the curatives Sulphur, CBS and DPG are added, and allowed to mix for 60 to 120 seconds and dumped at the temperature range of 80°C to 110°C. Final batch sheet out has been done in the laboratory two roll mill.

The present invention relates to unmodified Fuller’s earth as nanoclay based motorcycle tire tread composition offering low rolling resistance and high rubber elasticity and a tire having tread made of such composition. The rubber nanocomposite is based on solution based styrene butadiene rubber in combination with or without natural rubber and with or without poly butadiene rubber, unmodified Fuller’s Earth as nanofiller in combination with carbon black and with or without silica.

Example 1:
Table 2 shows compounding formulation according to one embodiment of the present invention.
Ingredients Control, phr Trial 1, phr Trial 2, phr Trial 3, phr
SSBR HPR 355 85 85 85 85
PBR 15 15 15 15
N330 50 45 40 35
Fuller’s Earth 0 5 10 15
Si69 0 0.4 0.8 1.2
TDAE Oil 10 10 10 10
Stearic Acid 2 2 2 2
Zinc Oxide 3 3 3 3
MC Wax 2 2 2 2
6 PPD 1.5 1.5 1.5 1.5
TMQ 1 1 1 1
Sulphur 1.5 1.5 1.5 1.5
CBS 0.75 0.75 0.75 0.75
DPG 0.25 0.25 0.25 0.25
Total 172.00 172.40 172.80 173.20

PHR – Parts per Hundred units of Rubber.
1. SSBR HPR 355 used as base polymer from JSR Corporation having ML(1+4) @ 100°C is 62 ± 5 MU.
2. Polybutadiene rubber from Reliance Industries with ML(1+4) @ 100°C is 45±5 MU.
3. N330 black as a reinforcing filler from Birla Carbon.
4. Fullers Earth nanoclay having a length between 1-3000 nanometer and diameter of 1-30 nanometer without any chemical modification and the aspect ratio of which is 5-50 used as a nanofiller from Haristons Mintech Pvt Ltd.
5. Silane Si69 as a coupling agent between Fullers Earth and Polymer from Tulsiram Hanumanbagas Gilada.
6. TDAE Oil used as a processing aid from Panama Petrochemical Ltd.
7. Stearic Acid used as an activator and processing aid from Godrej Industries
8. Zinc Oxide used as cure activator from Pondy Oxides & Chemicals Ltd.
9. Microcrystalline Wax used as antiozonant from Mahatha Petroleum Pvt.Ltd.
10. 6 PPD (1,3-Dimethylbutyl)-N'-phenyl-p-phenylenediamine) & TMQ (2,2,4-Trimethyl-1,2-Dihydroquinoline) used as antioxidants from Lanxess India Pvt Ltd.
11. Sulphur used as curative from Southern Minerals & Chemicals.
12. CBS (N-cyclohexyl-2-benzothiazolesulfenamide) used as primary accelerator from Nocil Ltd.
13. DPG (DiPhenyl Guanidine) used as secondary accelerator from PMC rubber chemical Pvt Ltd.
A. Master Batch Preparation
Preparation of master batch has been performed with the rotor speed of the mixer between 50 to 70 rpm and with the head temperature of the banbury maintained between 50°C to 70°C. The method of preparation of Master Batch includes following steps:
1. The mixing chamber is initially loaded with solution based styrene butadiene rubber (SSBR) and poly butadiene rubber (PBR) and masticated for 15–60 seconds.
2. Half the loading (50%) of reinforcing filler carbon black, unmodified Fuller’s Earth nanoclay, silane Si69 are added and allowed to mix for 20-60 seconds.
3. The remaining half of the carbon black, unmodified Fuller’s Earth nanoclay, silane Si69 along with TDAE oil, MC Wax, stearic acid, TMQ are loaded in the mixer and mixed for 20 – 60 seconds.
4. The silanization process is then carried out. The rotor speed is reduced to a range of 10-30 rpm and this process takes place for 30-90 seconds.
5. Sweeping down the chemicals in the orifice and allowed to mix further. The rotor speed is now increased backto the initial range of 50-70 rpm. The process is carried out until temperature reachesa range of 140°C-150°C.
6. Finally the mixed compound is dumpped at a temperature range of 155°C-165°C.

B. Repass Mixing Sequence
The repass mixing process has been performed with the rotation speed of the rotor between 50 to 70 rpm and with the head temperature of the banbury maintained between 50°C to 70°C. The repass mixing sequence includes following steps:
1. The mixed Master Batch compound is warmed for 15-45 seconds in the mixer and chemicals like zinc oxide and 6PPD are added.. The mixing process is carried out for 30-120 seconds and dumped.
2. The repass 1 compound is again loaded in the mixer for the second repass mixing process. The compound is loaded in the mixer and mixed for 30-120 seconds.

C. Final Batch Preparation
Mixing chamber is loaded with the master batch and the curatives Sulphur, CBS and DPG are added, and allowed to mix for 60 to 120 seconds and dumped at the temperature range of 80°C to 110°C. Final batch sheet out has been done in the laboratory two roll mill.

The present invention relates to unmodified Fuller’s earth as nanoclay based motorcycle tire tread composition offering low rolling resistance and high rubber elasticity and a tire having tread made of such composition. The rubber nanocomposite is based on solution based styrene butadiene rubber in combination with or without natural rubber and with or without poly butadiene rubber, unmodified Fuller’s Earth as a nano filler in combination with carbon black and with or without silica

Table 3 Properties of Compositions according to Table 1
S.No Properties Control Trial 1 Trial 2 Trial 3
1 Tan delta @60°C 0.152 0.131 0.125 0.123
2 Rebound resilience @23±2°C 38.47 42.16 44.45 45.1
INDEX
S.No Properties Control Trial 1 Trial 2 Trial 3
1 Tan delta @60°C 100 86.18 82.84 80.93
2 Rebound resilience@23±2°C 100 109.67 115.54 117.23

Interpretation of Result in Table 3 of Compositions of Table 2:
Tan delta at 60 degrees is a measure of low rolling resistance in a tire. The dynamic property of the rubber vulcanizate is measured on a dynamic mechanical analyzer (DMA Metravib +1000) with a dynamic strain 0.3%, temperature sweep from -40 to +80°C, Static strain 0.6%, Frequency: 10Hz in tension mode as per ASTM D5992.

1. Lower the tan delta value at 60 degrees better the low rolling resistance. Table 1 shows that the control compound has tan delta value 0.152 at 60 degrees. In trial 2, 10 phr of unmodified Fullers Earth nanoclay is replaced in place of carbon black and the tan delta at 60 degrees is 0.125. Thus, the low rolling resistance is improved by 18%.
2. The rubber elasticity of a tire tread compound is expressed in terms of rebound resilience and it is measured in Rebound resilience tester (Zwick Roell Make, Model 5109) as per DIN 53512 - ASTM D 7121. Higher the rebound resilience of the rubber compound, better the rubber elasticity. The rebound resilience of the control compound is 38.47. In the case of trial 2, replacement of 10 phr of unmodified Fullers Earth nanoclay in place of carbon black results in a rebound resilience value of 44.45. Thus, the rubber elasticity is improved by 16%.
3. The dosage of carbon black 50 Phr in control formulations (Table 1 & Table 2) is replaced with the unmodified Fullers Earth nanoclay material. In the trial compound formulations the dosage of carbon black is replaced upto 15 phr with the unmodified Fullers Earth nanoclay material.
4. The unmodified Fullers Earth nanoclay material is a naturally occurring material that is being used without any modification process. Thus the tire tread made with the unmodified Fullers Earth nanoclay material is more environment friendly as compared to the trial compound. It is another object of the present invention to provide cost effective and environmental friendly motor cycle tire tread compound using un-modified Fuller’s Earth nanoclay.
5. The use of unmodified Fullers Earth nanoclay in the rubber compound is cost effective as it is a naturally occurring material and replacing carbon black with Fullers Earth reduces the compound cost.
Example 2:
Table 4 shows compounding formulation according to second embodiment of the present invention.
Ingredients Control, phr Trial 1, phr Trial 2, phr Trial 3, phr
SSBR SLR 563 85 85 85 85
PBR 15 15 15 15
N330 50 45 40 35
Fuller’s Earth 0 5 10 15
Si69 0 0.4 0.8 1.2
TDAE Oil 10 10 10 10
Stearic Acid 2 2 2 2
Zinc Oxide 3 3 3 3
MC Wax 2 2 2 2
6 PPD 1.5 1.5 1.5 1.5
TMQ 1 1 1 1
Sulphur 1.5 1.5 1.5 1.5
CBS 0.75 0.75 0.75 0.75
DPG 0.25 0.25 0.25 0.25
Total 172.00 172.40 172.80 173.20

1. SSBR SLR 563 used as base polymer from JSR Corporation having ML (1+4) @ 100°C is 74±5 MU.
2. Polybutadiene rubber from Reliance Industries with ML (1+4) @100°C is 45±5 MU.
3. N330 black as a reinforcing filler from Birla Carbon.
4. Fullers Earth nanoclay having a length between 1-3000 nanometer and diameter of 1-30 nanometer without any chemical modification and the aspect ratio of which is 5-50 used as a nanofiller from Haristons Mintech Pvt Ltd.
5. Silane Si69 as a coupling agent between Fullers Earth and Polymer from Tulsiram Hanumanbagas Gilada.
6. TDAE Oil used as a processing aid from Panama Petrochemical Ltd
7. Stearic Acid used as an activator and processing aid from Godrej Industries
8. Zinc Oxide used as cure activator from Pondy Oxides & Chemicals Ltd.
9. Microcrystalline Wax used as antiozonant from Mahatha Petroleum Pvt.Ltd.
10. 6 PPD (1,3-Dimethylbutyl)-N'-phenyl-p-phenylenediamine) & TMQ (2,2,4-trimethyl-1,2-Dihydroquinoline) used as antioxidants from Lanxess India Pvt Ltd.
11. Sulphur used as curative from Southern Minerals & Chemicals.
12. CBS (N-cyclohexyl-2-benzothiazolesulfenamide) used as primary accelerator from Nocil Ltd.
13. DPG (Diphenyl guanidine) used as a secondary accelerator from PMC rubber chemical Pvt Ltd.

The present invention describes a method of preparation of the rubber composition for tyre treadnano composite with diene based rubber, in combination with or without other polymers like natural rubber and poly butdiene rubber; a reinforcing filler comprising of carbon black; and an unmodified Fuller’s Earth nano clay as a nano filler. The rubber composition is prepared by a thermo mechanical process in a banbury mixer.

A. Master Batch Preparation
Preparation of master batch has been performed with the rotor speed of the mixer between 50 to 70 rpm and with the head temperature of the banbury maintained between 50°C to 70°C. The method of preparation of Master Batch includes following steps:
1. The mixing chamber is initially loaded with solution based styrene butadiene rubber (SSBR) and poly butadiene rubber (PBR) and masticated for 15–60 seconds.
2. Half the loading (50%) of reinforcing filler carbon black, unmodified Fuller’s Earth nanoclay, silane si69 are added and allowed to mix for 20-60 seconds.
3. The remaining half of the carbon black, unmodified Fuller’s Earth nanoclay, silane si69 along with TDAE oil, MC Wax, stearic acid, TMQ are loaded in the mixer and mixed for 20 – 60 seconds.
4. The silanization process is then carried out. The rotor speed is reduced to a range of 10-30 rpm and this process takes place for 30-90 seconds.
5. Sweeping down the chemicals in the orifice and allowed to mix further. The rotor speed is now increased backto the initial range of 50-70 rpm. The process is carried out until temperature reachesa range of 140°C-150°C.
6. Finally the mixed compound is dumpped at a temperature range of 155°C-165°C.

B. Repass Mixing Sequence
The repass mixing process has been performed with the rotation speed of the rotor between 50 to 70 rpm and with the head temperature of the banbury maintained between 50°C to 70°C.The repass mixing sequence includes following steps:
1. The mixed Master Batch compound is warmed for 15-45 seconds in the mixer and chemicals like zinc oxide and 6PPD are added.The mixing process is carried out for 30-120 seconds and dumped.
2. The repass 1 compound is again loaded in the mixer for the second repass mixing process. The compound is loaded in the mixer and mixed for 30-120 seconds.

C. Final Batch Preparation
Mixing chamber is loaded with the master batch and the curatives Sulphur, CBS and DPG are added, and allowed to mix for 60 to 120 seconds and dumped at the temperature range of 80°C to 110°C. Final batch sheet out has been done in the laboratory two roll mill.

The present invention relates to unmodified Fuller’s earth as nanoclay based motorcycle tire tread composition offering low rolling resistance and high rubber elasticity and a tire having tread made of such composition. The rubber nanocomposite is based on solution based styrene butadiene rubber in combination with or without natural rubber and with or without poly butadiene rubber, unmodified Fuller’s Earth as a nano filler in combination with carbon black and with or without silica.

Table 5: Properties of Compositions according to Table 4
S.No Properties Control Trial 1 Trial 2 Trial 3
1 Tan delta @60°C 0.144 0.159 0.14 0.138
2 Rebound resilience @23±2°C 52.84 54.37 56.53 58.8
INDEX
S.No Properties Control Trial 1 Trial 2 Trial 3
1 Tan delta @60°C 100 110.42 97.22 95.83
2 Rebound resilience @23±2°C 100 102.9 106.98 111.28

Interpretation of results relating to Table 5:
1. Tan delta at 60 degrees is a measure of low rolling resistance in a tire. Lower the tan delta value at 60 degrees better the low rolling resistance. The dynamic property of the rubber vulcanizate is measured on a dynamic mechanical analyzer (DMA Metravib +1000) with a dynamic strain 0.3%, temperature sweep from -40 to +80°C, Static strain 0.6%, Frequency: 10Hz in tension mode as per ASTM D5992. Table 2 shows that the control compound has tan delta value 0.144 at 60 degrees. In trial 2, 10 phr of unmodified Fullers Earth nanoclay is replaced in place of carbon black and the tan delta at 60 degrees is 0.140. Thus, the low rolling resistance is improved by 3%.
2. The rubber elasticity of a tire tread compound is expressed in terms of rebound resilience. Higher the rebound resilience of the rubber compound, better the rubber elasticity and it is measured in Rebound resilience tester (Zwick Roell Make, Model 5109) as per DIN 53512 - ASTM D 7121.The rebound resilience of the control compound is 52.84. In the case of trial 2, replacement of 10 phr of unmodified Fullers Earth nanoclay in place of carbon black results in a rebound resilience value of 56.53. Thus, the rubber elasticity is improved by 7%.
3. The dosage of carbon black 50 Phr in control formulations (Table 1 & Table 2) is replaced with the unmodified Fullers Earth nanoclay material. In the trial compound formulations, the dosage of carbon black is replaced up to 15 phr with the unmodified Fullers Earth nanoclay material.
4. The unmodified Fullers Earth nanoclay material is a naturally occurring material that is being used without any modification process. Thus the tire tread made with the unmodified Fullers Earth nanoclay material is more environment friendly as compared to the trial compound. It is another object of the present invention to provide cost effective and environmental friendly motor cycle tire tread compound using un-modified Fuller’s Earth nanoclay.
5. The use of unmodified Fullers Earth nanoclay in the rubber compound is cost effective as it is a naturally occurring material and replacing carbon black with Fullers Earth reduces the compound cost.

Advantages
The rubber nanocomposite composition for motor cycle tyre tread of the present invention offers excellent low rolling resistance and high rubber elasticity. Also, it provide cost effective and environmental friendly motor cycle tire tread compound. ,CLAIMS:WE CLAIM:
1. A rubber nanocomposite composition for motor cycle tyre tread, comprising of:
one or more rubbers – 100 phr;
nanofillers – 1 – 25 phr;
reinforcing fillers – 30 – 85 phr;
coupling agent – 0 – 2.5 phr;
accelerators – 0.25 – 4 phr;
vulcanization agent – 1 – 5 phr;
cure activators – 1- 8 phr;
anti-degradants – 0.5 – 8.5 phr; and
process aid – 5 – 20 phr,
wherein the nanofiller is unmodified Fuller’s earth nanoclay having
a length between 1-3000 nanometer, diameter of 1-30 nanometer
and the aspect ratio of 5-50.

2. The rubber nanocomposite composition for motor cycle tyre tread as claimed in claim 1, wherein the one or more rubbers are selected from
solution based styrene butadiene rubber, natural rubber, poly butadiene rubber and combinations thereof.

3. The rubber nanocomposite composition for tyre tread as claimed in claim 1, wherein the reinforcing fillers are selected from carbon black and silica preferably in a weight ratio of 30-60: 0-25 phr.
4. The rubber nanocomposite composition for tyre tread as claimed in claim 1, wherein the cure activators are selected from stearic acid, zinc oxide and combinations thereof preferably in a weight ratio of 1-3: 2-5 phr.

5. The rubber nanocomposite composition for tyre tread as claimed in claim 1, wherein the anti-degradants are selected from Microcrystalline wax, (1,3-Dimethylbutyl)- N’-phenyl-p-phenylenediamine (6PPD), (2,2,4-trimethyl-1,2-dihydroquinoline) (TMQ) and combinations thereof, preferably in a weight ratio of 1-3:1-3: 0.5 – 2.5 phr.

6. The rubber nanocomposite composition for tyre tread as claimed in claim 1, wherein the vulcanization agent is sulphur.

7. The rubber nanocomposite composition for tyre tread as claimed in claim 1, wherein the cure accelerators are selected from CBS, DPG and combinations thereof, preferably in a weight ratio of 0.5 -2: 0.25 – 2 phr.

8. The rubber nanocomposite composition for tyre tread as claimed in claim 1, wherein the process aid is TDAE oil.

9. The rubber nanocomposite composition for tyre tread as claimed in claim 1, wherein the coupling agent is silane (Si69).
10. A tyre with tread portion comprising the rubber nanocomposite composition as claimed in claim 1.

11. The rubber nanocomposite composition for tyre tread as claimed in claim 1, wherein the rubber nanocomposite has low rolling resistance and high rubber elasticity.

12. A method of preparation of rubber nanocomposite composition for tyre tread, comprising of steps:
Master batch mixing by:
masticating of selected rubbers;
half loading (50%) of reinforcing filler carbon black, unmodified fuller’s earth nanoclay, silane (si69) are added and mixed;
adding of remaining 50% of carbon black, unmodified fuller’s earth nanoclay, silane (si69) along with process aid TDAE oil, microcrystalline wax, stearic acid, (2,2,4-trimethyl-1,2-dihydroquinoline) (TMQ) and mixing;
silanization at 10 – 30 rpm;
sweeping down the orifice and mixing the master batch rubber compound at 50 – 70 rpm at a temperature range of 140ºC to 150ºC; and
dumping at the temperature range of 155ºC - 165ºC,
wherein the rotational speed for mixing is maintained between 50 to 70 rpm and the temperature is maintained between 50°C to 70°Cm,
Repass mixing sequence:
mixing of master batch compound at 50 -70 rpm at a temperature
range between 50ºC and 70ºC;
warming of the master batch and mixing with chemicals zinc oxide
and (1,3-Dimethylbutyl)- N’-phenyl-p-phenylenediamine (6PPD);
and
dumping of the compound and further mixing,
Final batch preparation by:
mixing of master batch and the curatives sulphur, (N-cyclohexyl-2-
benzothiazolesulfenamide) and Diphenyl Guanidine (DPG);
dumping at a temperature range between 80ºC and 110ºC; and
sheet out the compound.