WO2022049591A1

WO2022049591A1 - A tyre tread rubber composition and method thereof

Info

Publication number: WO2022049591A1
Application number: PCT/IN2021/050556
Authority: WO
Inventors: Brindha Senthilraja; Sankaran Kumar; Kadambanathan THIAGARAJAN; Viswanathan Sivaramakrishnan
Original assignee: Tvs Srichakra Limited
Priority date: 2020-09-04
Filing date: 2021-06-09
Publication date: 2022-03-10

Abstract

The present invention relates to a high performance motor cycle tyre tread rubber composition, with improved wet and dry traction. The elastomeric composition of tyre tread comprising of blends of natural rubber and non-oil extended solution styrene butadiene rubber; reinforcing fillers including carbon black and silica, a processing aid hydrocarbon resin, having softening point 120 °C to 130 °C containing C-H stretching, methylene (-CH2-), methyl (-CH3) and phenyl (-C6H5) groups and its molecular weight lesser than 1000g/mol with a glass transition temperature Tg lesser than 100°C and other rubber additives also offers superior processability and filler dispersion.

Description

A TYRE TREAD RUBBER COMPOSITION AND METHOD THEREOF

FIELD OF THE INVENTION:

The present invention relates to the field of rubber composition for use in tyres. More particularly, it provides a tyre tread rubber composition comprising diene based rubber blend of non-oil extended solution styrene butadiene rubber and natural rubber and method thereof. Advantageously, the present invention relates to a rubber composition for tyre tread capable of providing a better wet and dry traction.

BACKGROUND OF THE INVENTION:

As rubbers for a tire tread, rubbers having a high frictional force have been sought from the viewpoint of safety. On the other hand, a tire that has a small rolling resistance, that is, rubbers having a small hysteresis loss at the time of tire rolling have been sought from the viewpoint of the environment and health. Various proposals have been made to formulate a hard foreign substance or a hollow particle into a rubber to thereby form a micro irregularity on the surface of a rubber layer, whereby a water-film present on the surface of the ice is removed during a running of a tire and the friction on the ice is increased, but practically satisfactory results have not been obtained yet. There are caused other problems such as the increase in the hardness of the rubber and the loss of flexibility of the rubber whereby the resultant tire is difficult to follow the contours of the road.

Rubber compositions used for tyre treads are traditionally made with aromatic oil to improve wet traction and also, it enables processability. There is a global approach towards the limitation of aromatic oil or elimination of aromatic oil in tyre treads rubber composition. The lower aromaticity is obtained through the selection of various ingredients viz., base polymer selection (TDAE oil extended Rubber(s)), use of TDAE oil, use of low aromaticity oils like naphthenic oil, environmental friendly oils etc. This invention is to fulfill the need of the tyre manufacturers, in terms of environment and health.

US Patent No. 8,697,793 relates to a rubber composition that includes from 5 to 70 parts by mass of silica having a BET specific surface area from 50 to 200 m.sup 2/g per 100 parts by mass of a diene rubber. The rubber composition includes from 1 to 25 parts by mass of an aromatic modified terpene resin and at least one terpene per 100 parts by mass of a diene rubber. The rubber composition further includes from 1 to 70 parts by mass of a naphthenic oil per 100 parts by mass of a diene rubber, where a CN % proportion of a CA %CP %CN % ratio calculated according to ASTM D2140/ASTM D3238 is the greatest and the CA % proportion is less than 15%, and a dynamic viscosity at 4O.degree. C. is from 17 to 30 mm.sup.2/sec.

US Patent No. 8,362,118 relates to a rubber composition for use in tires including from 60 to 120 parts by weight of a silica having a CTAB specific surface area of from 70 to 175 m.sup.2/g and from 3 to 25 parts by weight of an aromatic modified terpene resin excluding terpene phenol resins per 100 parts by weight of a diene rubber including from 30 to 80 weight % of a terminal-modified styrene-butadiene rubber and from 10 to 50 weight % of a butadiene rubber. An average glass transition temperature of the diene rubber is -55. degree. C. or lower and an average glass transition temperature of a component formed from the diene rubber, the aromatic modified terpene resin, and an optional plasticizer is -45.degree. C. or lower.

US Patent No. 8,247,489 relates to a rubber composition blended with an inorganic filler, the rubber composition includes a blend of: 100 parts by weight of a diene rubber; 1 to 150 parts by weight of an inorganic filler; and 0.1 to 30 parts by weight of a copolymer composed of a segment composed of a polyamide polymer and a segment composed of a diene polymer. The segment composed of the diene polymer has a number average molecular weight of not less than 10000.

US Patent No. 7,652,096 relates to a rubber composition for a tire tread including 100 parts by weight of a diene -based rubber and 5 to 150 parts by weight of carbon black having a nitrogen adsorption specific area N.sub.2SA (m.sup.2/g) of 80 to 150 and satisfying a relationship between a TINT (%) and dibutyl phthalate absorption DBPA (ml/100 g) of TINT (%)>1.4 DBPA (ml/100 g) and capable of increasing the frictional force without impairing the hysteresis loss.

US Publication No. 20150298511 relates to a rubber composition for a run-flat tire comprises from 20 to 100 parts by weight of a reinforcing filler per 100 parts by weight of a diene rubber containing from 10 to 80 wt. % of butadiene rubber and from 10 to 40 wt. % of natural rubber; wherein the reinforcing filler contains at least 50 wt. % of carbon black; a mode diameter Dst in a mass distribution curve of a Stokes diameter of aggregates of the carbon black is at least 145 nm; a nitrogen adsorption specific surface area N.sub.2SA is from 45 to 70 m.sup.2/g; and a ratio N.sub.2SA/IA of the nitrogen adsorption specific surface area N.sub.2SA to an iodine adsorption IA (units: mg/g) is from 1.00 to 1.40. US Publication No. 20160177072 relates to a rubber composition for tires including: a rubber component including at least one selected from the group consisting of a specific non-oil extended polybutadiene rubber and a specific oil extended polybutadiene rubber; a phenylenediamine antioxidant; a specific nonionic surfactant; and carbon black and/or silica, the rubber composition having an amount of diene rubber of 70-100% by mass per 100% by mass of the rubber component, the rubber composition having an amount of the phenylenediamine antioxidant of 1.0-8.0 parts by mass, an amount of the nonionic surfactant of 0.1 -5.0 parts by mass, and a combined amount of carbon black and silica of 20-45 parts by mass, each per 100 parts by mass of the rubber component.

Publication No. KR920004783 (Bl) relates to a rubber composition comprising (A) a base rubber composition consisting of 10-50 wt. pts. natural rubber 10-50 wt. pts. solution- polymerized styrene butadiene rubber and 30-50 wt. pts. butadiene having a vinyl content of 40-70 %, (B) 30-80 wt. pts. of carbon black having an iodine adsorption value of 50-90 ml/g, a DBP adsorption value of 120-150 cc/g and a tint strength of 90-100, and (C) 5-30 wt. pts. of silica containing 10-15 wt.% silane coupling agent.

Publication No. JP2006249403 (A) relates to a rubber composition that comprises: 100 pts. mass of a rubber component composed of 50 wt% or over of a solution polymerized styrene butadiene rubber with wt. average molecular wt. of 500,000-2,500,000, 40 wt% or less of a natural rubber and 40 wt% or less of a polybutadiene rubber; 50-120 pts. mass of a reinforcing filler containing a carbon black with a nitrogen adsorption specific surface area of 100-250 m<SP>2</SP>/g, an iodine adsorption volume of 110-200 mg/g and a ratio of the specific surface area based on cetyl trimethyl ammonium bromide adsorption to that based on iodine is adsorption of 0.85-1.2, and 0-100 pts.mass of silica relative to 100 pts.mass of the rubber components; and a synthetic resin.

Indian Publication No. 201721043059 relates to a rubber composition comprising: (a) 20 - 45 phr of at least one natural rubber based polymer; (b) 20 - 45 phr of at least one polybutadiene polymer; (c) 10 - 60 phr of at least one styrene butadiene polymer; (d) 40 - 85 phr of at least one reinforcing filler; and (e) 5 - 25 phr of at least one process aid. The process of the preparation of the rubber/tire composition is also disclosed. US Patent No. 10,040,927 relates to a rubber composition for tires that comprises: a natural rubber, a diene-based blended rubber containing a solution-polymerized SBR and an emulsion-polymerized SBR, an aromatic modified terpene resin, a silica, and a carbon black. The solution -polymerized SBR contains a specific solution-polymerized SBR having a block containing an isoprene unit at one terminal thereof and a modified terminal for silica at the other terminal thereof. The styrene unit content in the emulsion-polymerized SBR is from 35 to 50 mass %. The content of the natural rubber and the total content of the solution-polymerized SBR and the emulsion-polymerized SBR in the diene-based blended rubber are specified, and the contents of aromatic modified terpene resin, the silica, and the carbon black relative to the content of the diene-based blended rubber are specified.

US Patent No. 6,058,994 relates to a rubber composition for a tire tread containing: (i) 100 parts by weight of a diene rubber, and (ii) 1 to 20 parts by weight of an elastic gas -encapsulated thermoplastic resin hollow particle having a particle size of 5-300 .mu.m, which is obtained by expanding, upon heating during vulcanization, a thermally expansible thermoplastic resin containing an encapsulated liquid or solid substance capable of generating a gas by vaporization, decomposition or chemical reaction upon heating to form the hollow-type expanded particle and, optionally containing (iii) 1 to 20 parts by weight of a short fiber or (iv) 1 to 20 parts by weight of a hard particle.

US Patent No. 10,301,459 relates to a pneumatic tire with a circumferential tread composition which contains a unique combination of styrene/butadiene elastomers, both solution and emulsion prepared, a plurality of traction promoting resins and reinforcing filler which contains a specific combination of a selected carbon black and a pre-hydrophobated precipitated silica.

US Patent No. 10,329,406 relates to rubber compositions and articles made from such rubber compositions that are based upon a cross-linkable elastomer composition, the cross-linkable elastomer composition comprising, per 100 parts by weight of rubber (phr) between 70 phr and 100 phr of an epoxidized rubber component selected from an epoxidized polybutadiene rubber (eBR), an epoxidized styrene -butadiene rubber (eSBR), or combinations thereof, wherein the epoxidized rubber component has a Tg of between -80.degree. C. and -HO.degree. C. and an epoxy-function content of between 1 mol % and 25 mol %. Such rubber compositions may further include between 30 phr and 150 phr of a plasticizing resin, silica and a coupling agent that is a monohydroxysilane polysulfide having a form (Formula I) wherein radicals R, identical or different, are hydrocarbon groups, radicals R', identical or different, are divalent linking groups and x is equal to or greater than 2.

Hence, the present invention aims to provide high performance motor cycle tire tread composition containing elastomeric blends using hydrocarbon resin as a special process aid to provide improved wet and dry traction.

OBJECTS OF THE INVENTION:

It is the primary object of the present invention to provide a tyre tread rubber composition with improved wet and dry traction.

It is the principal object of the present invention to provide high performance motor cycle tyre tread rubber composition using a hydrocarbon resin, having softening point 120 °C to 130 °C containing C-H stretching, methylene (-CH2-), methyl (-CH3) and phenyl (-CeHs) groups and its molecular weight lesser than lOOOg/mol with a glass transition temperature T_g lesser than 100°C.

It is another object of the present invention to provide a tyre tread rubber composition constituting a hydrocarbon resin offering superior filler dispersion.

It is another object of the present invention to eliminate the use of aromatic oil.

It is yet another object of the present invention to provide better processing characteristics.

SUMMARY OF THE INVENTION

It is the principle aspect of the present invention to provide a tyre tread rubber composition, comprising of: a rubber blend - 100 parts comprising non-oil extended solution styrene butadiene rubber or natural rubber or it’s blends or other diene rubbers, one or more reinforcing fillers 5 - 100 phr, processing aid - 1-30 phr, coupling agent - 1.5 phr - 4.0 phr, vulcanization activators - 1.5 - 4.0 phr, anti -degradants - 0.5-6.5 phr, cure accelerators - 0.5 - 3.0 phr, and vulcanization agent - 0.5 - 4.0 phr, wherein the processing aid is hydrocarbon resin with functional group containing CH stretching, methylene (-CH2-), methyl (-CH3) and phenyl (- CfiHs) groups having softening point 120 - 130 °C and molecular weight lesser than lOOOg/mol with a glass transition temperature T_g lesser than 100°C.

It is another aspect of the present invention to provide a tyre tread rubber composition, wherein the diene rubbers namely SBR, OESBR, BR, OEBR, ENR or blend of two or three diene rubbers.

It is another aspect of the present invention to provide a tyre tread rubber composition wherein at least one of the reinforcing fillers is carbon black of grades N100 series, N200 series, N300 series or blend of any of these two carbon black grades.

It is another aspect of the present invention to provide a tyre tread rubber composition, wherein at least one of the reinforcing fillers is inorganic filler such as silica, silicates, mica, calcium carbonate, clay, nanoclay.

It is another aspect of the present invention to provide a tyre tread rubber composition, wherein said coupling agent is sulfur containing organo silane.

It is another aspect of the present invention to provide a tyre tread rubber composition, wherein said vulcanization activators comprise zinc oxide and stearic acid.

It is another aspect of the present invention to provide a tyre tread rubber composition, wherein said anti-degradants comprises 6PPD (N-(l,3-dimethylbutyl)-N’-phenyl-p-phenylenediamine) or TQ (1,2 dihydro 2,2,4 -trimethyl quinoline) and microcrystalline wax or its mixtures.

It is another aspect of the present invention to provide a tyre tread rubber composition, wherein said cure accelerators comprises N-cyclohexyl-2-benzothiazolesulfenamide (CBS) and Diphenyl guanidine (DPG) and also the types of accelerators such as guanidines, thiazoles, sulphenamides and thiuram sulphides or its mixtures.

It is another aspect of the present invention to provide a tyre tread rubber composition, wherein said vulcanization agent is sulfur or different grades of insoluble sulphur. It is another aspect of the present invention to provide a tyre tread rubber composition, wherein the wet traction of the rubber composition is in the range of 0.811 to 0.835 tan delta at 0°C and dry traction in the range of 0.0125 - 0.0168 MPa"¹.

It is yet another aspect of the present invention to provide a motorcycle tyre comprising the tyre tread rubber composition in a tread or tread cap.

It is an additional aspect of the present invention to provide a process of preparation of tyre tread rubber composition, comprising of the steps:

Preparation of master batch comprising: mixing of rubbers for 0-30 seconds in a mixing chamber at 50 - 60 rpm and head temperature of the banbury maintained between 85 and 90°C; further adding 80 - 90 % of the carbon black reinforcing filler and 80 - 90% of the inorganic reinforcing filler and mixing for 50 to 70 seconds at around 110 - 125°C; adding of processing aid, rubber chemicals along with remaining amount of reinforcing fillers and mixing for 50 - 60 seconds; adding coupling agent for silanisation at 20-30 rpm at around 130-140°C for 20-30 seconds; sweeping down in the orifice and allowed to mix for 50 - 60 seconds; dumping of the compound at temperature range of 150°C to 165°C; sheeting out the rubber compound using laboratory two-roll mill; mixing of rubber compound sheet along with chemicals zinc oxide, and anti- degradants for 110 - 120 seconds using a banbury mixer; dumping at a temperature range of 135 °C - 150°C and sheeting out the rubber compound using laboratory two roll mill; further mixing of the rubber compound sheet for 110 -120 seconds in a mixing chamber of a banbury; dumping at a temperature range of 135°C - 150°C and sheeting out the rubber compound using a two-roll laboratory mill to obtain master batch;

Preparation of final batch by mixing master batch compound along with the vulcanizing agents and cure accelerators for 50 - 80 seconds; dumping at a temperature range of 85°C to 120°C; and sheeting out the rubber compound using laboratory two roll mill, wherein the processing aid is hydrocarbon resin with functional group containing CH stretching, methylene (-CH2-), methyl (-CH3) and phenyl (- CeHs) groups having softening point 120°C - 130°C and molecular weight lesser than 1000 g/mol with a glass transition temperature T_g lesser than 100°C.

DETAILED DESCRIPTION OF THE INVENTION:

The present invention relates to a high performance motor cycle tyre tread composition, capable of providing a motorcycle tyre with improved wet and dry traction.

In accordance with the present invention, there is provided a rubber composition for tyre tread comprising of a diene based rubber blend comprising non-oil extended solution styrene butadiene rubber and natural rubber; reinforcing fillers comprising of carbon black and silica; and hydrocarbon resin as a processing aid.

In accordance with the present invention, there is provided a rubber composition for tyre tread also consists of coupling agent sulfur containing organosilane (SI75); vulcanization activators comprising zinc oxide and stearic acid; anti -degradants comprising 6PPD (N-(l,3-dimethylbutyl)- N’-phenyl-p-phenylenediamine) and microcrystalline wax; cure activators comprising N- cyclohexyl-2-benzothiazolesulfenamide (CBS) and Diphenylguanidine (DPG); vulcanization agent sulfur.

An embodiment of the present invnetion discloses a rubber composition comprising of a rubber blend - 100 parts comprising non oil extended solution styrene butadiene rubber or natural rubber or it’s blends or other diene rubbers, one or more reinforcing fillers 5-100 phr, processing aid -1-30 phr, coupling agent - 1.5 phr -4.0 phr, vulcanization activators- 1.5- 4.0 phr, anti -degradants- 0.5- 6.5 phr, cure accelerators - 0.5 - 3.0 phr, and vulcanization agent- 0.5 - 4.0 phr, wherein the processing aid is hydrocarbon resin with functional group containing CH stretching, methylene (- CH2-), methyl (-CH3) and phenyl (-CeHs) groups having softening point 120 - 130 °C and molecular weight lesser than lOOOg/mol with a glass transition temperature T_g lesser than 100°C. The diene rubbers are chosen from a combination of Styrene -butadiene or styrene -butadiene rubber (SBR) SBR, Oil extended Natural rubber or Oil extended Styrene Butadiene rubber (OESBR), Butadiene rubber BR, Oil Extended Butadiene rubber (OEBR), Epoxidized natural rubber (ENR) or blend of two or three diene rubbers.

Reinforcing fillers are selected from carbon black of grades N100 series, N200 series, N300 series or blend of any of these two carbon black grades. Atleast one of the reinforcing filler comprises inorganic filler selected from singly or a combination of silica, silicates, mica, calcium carbonate, clay, nanoclay. Coupling agent: is sulfur containing organo silane. Vulcanization activators comprise zinc oxide and stearic acid. Anti-degradants comprises 6PPD (N-(l, 3-dimethylbutyl)-N’- phenyl-p-phenylenediamine) or TQ (1, 2 dihydro 2, 2, 4 -trimethyl quinoline) and microcrystalline wax or its mixtures. Cure accelerators comprises N-cyclohexyl-2-benzothiazolesulfenamide (CBS) and Diphenyl guanidine (DPG) and also the types of accelerators such as guanidines, thiazoles, sulphenamides and thiuram sulphides or its mixtures. Vulcanization agent is sulfur or different grades of insoluble sulphur. Another embodiment comprises of a motorcycle tyre comprising the tyre tread rubber composition of the present invention.

Method of preparation of the Rubber compositions:

An embodiment of the present invention discloses a method of preparation of a rubber composition for tyre tread with diene based rubber blend comprising non-oil extended solution styrene butadiene rubber and natural rubber; a reinforcing filler comprising of carbon black and silica; and hydrocarbon resin as a processing aid.

The steps comprises of:

Rubber composition is prepared by a thermo mechanical process. To demonstrate the process is carried out using a banbury mixer.

A) Method of preparation of master batch comprising of the steps:

Step 1: Preparation of master batch has been performed with the rotation speed of the mixer between 50 to 60 rpm and with the head temperature of the banbury maintained between 85 to 90 °C. i) mixing chamber has been charged with the non-oil extended solution styrene butadiene rubber (SSBR) and natural rubber (NR), and allowed to mix for 0 to 30 seconds, ii) Addition of 80 to 90% of the reinforcing filler carbon black and 80 to 90% of the inorganic reinforcing filler silica, silane coupling agent Si75, and allowed to mix for 50 to 70 seconds for silanisation at around 110 to 125°C, iv) The remaining carbon black and silica, along with process aids and allowed to mix for 50 to 60 seconds, iii) The process of silanisation has been done by mixing coupling agent SI75 with the reduced rotor speed 20 to 30 rpm at around 130 to 140°C for 20-30 seconds, v) sweeping down in the orifice and allowed to mix for 50 to 60 seconds and the compound has been dumped at the temperature in the range of 150°C to 165°C. The compound has been sheeted out in the laboratory two-roll mill.

Step II:

Mixing chamber of the banbury charged with the Step I master batch, chemicals zinc oxide and 6PPD (N-(l,3-dimethylbutyl)-N’ -phenyl -p-phenylenediamine), and allowed to mix for 110 to 120 seconds and dumped in the temperature range of 135°C to 150°C. The compound has been sheeted out in the laboratory two-roll mill.

Step III:

Mixing chamber of the banbury charged with the Step II master batch, and allowed to mix for 110 to 120 seconds and dumped at the temperature range of 135 °C to 150°C. The compound has been sheeted out in the laboratory two-roll mill.

B) Method of preparation of final batch comprising of the steps:

Mixing chamber charged with the Step III master batch and the curatives Sulphur, CBS (N- cyclohexyl-2-benzothiazolesulfenamide) and DPG (Diphenylguanidine) are added, and allowed to mix for 50 to 80 seconds and dumped at the temperature range of 85 °C to 120°C. Final sheet out has been done in the laboratory mill.

Example 1:

The present invention will be explained further by examples, but the scope of the present invention is, ofcourse not limited to these examples.

The present invention relates to a high performance motor cycle tyre tread rubber compositions according to Table 1 intended for the manufacture thereof.

In order to demonstrate the invention, the experiment is performed with reference to Table 1 representing :- ratios of compounds to obtain the rubber composition are provided, in which C2 and C3 represents rubber compositions comprising of diene based rubber blend comprising non-oil extended solution styrene butadiene rubber and natural rubber; reinforcing filler carbon black and silica and varying dosage value range of hydrocarbon resin and Cl is control representing rubber composition containing aromatic oil, Elasto 710 grade.

Rubber composition containing aromatic oil, Elasto 710 grade as represented in Cl is used to compare with the rubber composition of the present invention (C2 and C3) containing hydrocarbon resin to produce a high performance motor cycle tyre tread composition.

Table 1: Rubber compounds and compositions

1- HPR 355 HR is non-oil extended solution styrene butadiene rubber (SSBR) with 26 - 28 % of styrene content, 55.5 % to 59.5% of vinyl content and

T„ of -21 °C to -27°C (HPR 355 HR from JSR corporation).

2- Indian Standard Natural Rubber ISNR 20 with the Mooney Viscosity, ML (1+4) at 100°C is 76

MU. 3- ASTM Grade N220 from Birla Carbon, India. It is the reinforcing filler ISAF, Intermediate Superior Abrasion Furnace having the Iodine adsorption No. 116 to 126 mg/gm, tinting strength value between 110 to 129 % ITRB, statistical thickness surface area value between 102 to 117 m²/gm.

4- Ultrasil VN3 silica from Insilico Ltd, Evonik Industries GmbH, India. It is the reinforcing filler having nitrogen surface area value 170 to 190 m /gm and it is used for the present invention is to provide a high performance motor cycle tyre treads.

5- Si75 is a bifunctional, sulfur- containing organosilane from Evonik Resource efficiency GmbH, Germany. It is used to provide a satisfactory bonding of, chemical/or physical nature between the inorganic filler and diene elastomer(s).

6- Zinc oxide from POCL Enterprises Limited, India. It is an activator added to the rubber compound to activate sulphur vulcanization.

7- Stearic acid from 3F Industries Ltd., India. It is used as a Process aid. Also, Zinc oxide and Stearic acid are added to form zinc soap, improves the solubility of zinc oxide in the compound, and with the accelerator to form a complex, this complex reacts with sulphur to produce a strong cure activating system.

8- 6PPD (N-(l,3-dimethylbutyl)-N’-phenyl-p-phenylenediamine) from Nocil Limited, India. It is added to the rubber composition to provide resistance to thermo-oxidative ageing of elastomers.

9- MC Wax (Microcrystalline wax) from Mahatha petroleum private Limited, India. It is used to protect against degradation by ozone.

10- Aromatic Oil from Indian Oil Corporation Limited, India. It is used in the control compound is to compare with the hydrocarbon resin used in the present invention to produce a high performance motor cycle tyre tread composition.

11- Hydrocarbon Resin Operra™ 120 having softening point 120°C - 130°C and molecular weight lesser than 1000 g/mol with a glass transition temperature T_g lesser than 100°C from Exxon Mobil, Singapore.

12- CBS (N-cyclohexyl-2-benzothiazolesulfenamide) from Nocil Limited, India. It is a delayed action accelerator suitable for diene rubbers.

13- DPG (Diphenylguanidine) from PMC Rubber Chemicals India Pvt ltd., West Bengal, India. It is secondary accelerator, used to activate the primary accelerator.

14- Sulphur is the vulcanizing agent from The Standard Chemical Co. Pvt Ltd, India. Results:

Characterization of Cured Rubber Vulcanizate and Uncured Rubber Compound:

The compound properties are listed in Table 2 below-

Measurements and Tests:

The purpose of these tests is to measure the improved properties of the compositions related to the invention against control composition. For this, three compositions Cl, C2 & C3 prepared based on SSBR: NR (80: 20) blend reinforced by carbon black and silica containing hydrocarbon resin (C2 & C3) against SSBR: NR (80: 20) blend reinforced by carbon black and silica containing aromatic oil (Cl) are prepared and evaluated.

The present invention provides a 100 parts by weight of rubber composition C2, SSBR: NR (80:20) blend based rubber composition containing hydrocarbon resin 10 phr gave process safety, t value improved by 5.43% and the dispersion rating increased by 14.11 % when compared to 10 phr aromatic oil containing SSBR: NR (80:20) blend based rubber composition Cl (Control).

Moreover, further addition of hydrocarbon resin from 10 to 20 phr in the SSBR: NR (80:20) blend based rubber composition C3, improved the process safety t , to a greater extent i.e., 55.56% and the dispersion rating increased by 4.70% when compared to 10 phr aromatic oil containing SSBR: NR (80: 20) blend based rubber composition Cl.

The present invention also relates to a 100 parts by weight of rubber composition C2, SSBR: NR (80:20) blend based rubber composition containing 10 phr of hydrocarbon resin gave hardness 65 Shore A.

And, further dosage increase of hydrocarbon resin from 10 to 20 phr in SSBR: NR (80: 20) blend based rubber composition C3 gave hardness 64 Shore A.

The present invention relates to a 100 parts by weight of rubber composition C2, SSBR: NR (80: 20) blend based rubber composition containing 10 phr of hydrocarbon resin gave high performance motor cycle tyre tread compound with 9.0% improved wet traction along with 15.74% improved dry traction when compared to 10 phr aromatic oil containing SSBR: NR (80: 20) blend based rubber composition Cl. Moreover, further dosage increase of hydrocarbon resin from 10 to 20 phr in SSBR: NR (80: 20) blend based rubber composition C3 gave 5.87% improved wet traction along with 55.56 % improved dry traction when compared to 10 phr aromatic oil containing SSBR: NR based rubber composition C 1.

Hence, hydrocarbon resin containing SSBR: NR (80:20) blend based rubber composition C2 and C3 gave improved wet and dry traction when compared to aromatic oil containing SSBR:NR (80:20) blend based rubber composition Cl. Also, the hydrocarbon resin containing rubber compounds C2 & C3 gave better processing properties than aromatic oil containing control compound Cl. Moreover, the hydrocarbon resin containing SSBR: NR (80: 20) blend based rubber vulcanizate C2 and C3 gave 64 - 65 Shore A hardness.

Table 2: Compound Properties

Better processability (Process Requirements) of a Rubber Compound:

Ml. Mooney Scorch Characteristics (pre vulcanization characteristics using large rotor) for processability: The Mooney Scorch measurements are carried out with a Mooney Viscometer (MV 2000 Alpha technologies, USA) according to ASTM DI 646. MV indicates the minimum viscosity, ts indicates the time to scorch (MV+5) which indicates the processing properties (process safety) and t35 indicates the time to cure (MV+35)

M2. Dispersion Rating

Hydrocarbon resin is used to improve processability (incorporation, dispersion and distribution) via reducing the hardness of the vulcanizers and increasing their elasticity and cold flexibility. The resins and oils can effectively increase molecular mobility allowing the rubber molecules quickly covers the voids or holes among the reinforcing filler aggregates which achieve subsequent phase of dispersion.

Dispersion analysis is carried out with a Dispergrader, Model DGAV SR (Alpha Technologies, USA) according to ASTM D7723 for rubber vulcanizates. Dispersion Rating is from 1 to 10. The No.l indicates the poor dispersion and the No.10 indicates the excellent dispersion.

M3. Shore A Hardness:

Shore A Hardness of the Rubber Vulcanizate is assessed in accordance with ASTM D 2240.

M4. Dynamic properties of the rubber vulcanizate:

The dynamic properties of the rubber vulcanizate are measured on a dynamic mechanical analyzer (DMA Metravib +1000) with a dynamic strain 0.1%, temperature sweep from -120 to +100°C, frequency: 20Hz in tension mode as per ASTM D5992.

Tan delta at 0°C is commonly used as a predictor of tyre wet traction. Also, higher the tan delta value at 0°C, better the wet traction.

Loss compliance J’ ’ at 30°C is commonly used as a predictor for dry traction. Higher is better.

Claims

WE CLAIM:

1. A tyre tread rubber composition, comprising of: a rubber blend - 100 parts comprising styrene butadiene rubber or natural rubber or it’s blends or other diene rubbers; one or more reinforcing fillers 5 - 100 phr; processing aid - 1-30 phr; coupling agent - 1.5 phr - 4.0 phr; vulcanization activators - 1.5 - 4.0 phr; anti -degradants - 0.5-6.5 phr; cure accelerators - 0.5 - 3.0 phr; and vulcanization agent - 0.5 - 4.0 phr, wherein the processing aid is hydrocarbon resin with functional group containing CH stretching, methylene (-CH2-), methyl (-CH3) and phenyl (-C6H5) groups having softening point 120 - 130 °C and molecular weight lesser than lOOOg/mol with a glass transition temperature T_g lesser than 100°C.

2. The tyre tread rubber composition as claimed in claim 1, wherein the diene rubbers namely SBR, OESBR, BR, OEBR, ENR or blend of two or three diene rubbers.

3. The tyre tread rubber composition as claimed in claim 1, wherein at least one of the reinforcing fillers is carbon black of grades N100 series, N200 series, N300 series or blend of any of these two carbon black grades.

4. The tyre tread rubber composition as claimed in claim 1, wherein at least one of the reinforcing fillers is inorganic filler such as silica, silicates, mica, calcium carbonate, clay, nanoclay.

5. The tyre tread rubber composition as claimed in claim 1, wherein said coupling agent is sulfur containing organo silane.

6. The tyre tread rubber composition as claimed in claim 1, wherein said vulcanization activators comprises zinc oxide and stearic acid.

7. The tyre tread rubber composition as claimed in claim 1, wherein said anti -degradants comprises 6PPD (N-(l, 3-dimethylbutyl)-N’ -phenyl -p-phenylenediamine) or TQ (1, 2 dihydro 2, 2, 4 - trimethyl quinoline) and microcrystalline wax or its mixtures.

8. The tyre tread rubber composition as claimed in claim 1, wherein said cure accelerators comprises N-cyclohexyl-2-benzothiazolesulfenamide (CBS) and Diphenyl guanidine (DPG) and also the types of accelerators such as guanidines, thiazoles, sulphenamides and thiuram sulphides or its mixtures.

9. The tyre tread rubber composition as claimed in claim 1, wherein said vulcanization agent is sulfur or different grades of insoluble sulphur.

10. The tyre tread rubber composition as claimed in claim 1, wherein the wet traction of the rubber composition is in the range of 0.811 to 0.835 tan delta at 0°C and dry traction in the range of 0.0125 - 0.0168 MPa ¹.

11. A motorcycle tyre comprising the tyre tread rubber composition according to claim 1 in a tread or tread cap.

12. A process of preparation of tyre tread rubber composition, comprising of the steps:

Preparation of master batch comprising: mixing of rubbers for 0-30 seconds in a mixing chamber at 50 - 60 rpm and head temperature of the banbury maintained between 85 and 90 °C; further adding 80 - 90 % of the carbon black reinforcing filler and 80 - 90% of the inorganic reinforcing filler and mixing for 50 to 70 seconds at around 110 - 125°C; adding of processing aid, rubber chemicals along with remaining amount of reinforcing fillers and mixing for 50 - 60 seconds; adding coupling agent for silanisation at 20-30 rpm at around 130-140°C for 20-30 seconds; sweeping down in the orifice and allowed to mix for 50 - 60 seconds; dumping of the compound at temperature range of 150°C to 165°C; sheeting out the rubber compound using laboratory two-roll mill; mixing of rubber compound sheet along with chemicals zinc oxide, and anti- degradants for 110 - 120 seconds using a banbury mixer; dumping at a temperature range of 135°C - 150°C and sheeting out the rubber compound using laboratory two roll mill; further mixing of the rubber compound sheet for 110 -120 seconds in a mixing chamber of a banbury; dumping at a temperature range of 135°C - 150°C and sheeting out the rubber compound using a two-roll laboratory mill to obtain master batch;

Preparation of final batch by mixing master batch compound along with the vulcanizing agents and cure accelerators for 50 - 80 seconds; dumping at a temperature range of 85°C to 120°C; and sheeting out the rubber compound using laboratory two roll mill, wherein the processing aid is hydrocarbon resin with functional group containing CH stretching, methylene (-CH2-), methyl (-CH3) and phenyl (- CeHs) groups having softening point 120°C - 130°C and molecular weight lesser than 1000 g/mol with a glass transition temperature T_g lesser than

100°C.

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