Claims:WE CLAIM:
1. An elastomeric nanocomposite reinforced with dual filler composition, comprising:
one or more elastomeric compounds – 100 parts by weight;
dual filler composition comprising chemically un-modified Fuller’s Earth (FE) nanoclay – 10 – 70 phr, primary filler 30 – 90 phr; and additives,
wherein the additives comprises of vulcanization agent - 3 - 10 phr; coupling agent – 1.20 – 3 phr, vulcanization activators – 1.50 – 4.50 phr, anti-degradants – 1 - 2 phr; anti-aging additives – 0.5-1 phr; cure accelerators – 0.20 – 1.20 phr; and processing aid, and
wherein the filler composition for reinforcement comprises chemically unmodified fuller’s earth nanoclay of acicular structure having a length between range 10 and 5000 nanometer with diameter range between 1 and 30 nanometer and carbon black as primary filler.

2. The elastomeric nanocomposite reinforced with dual filler composition as claimed in claim 1, wherein the said elastomeric compounds is selected from one or more of natural rubber, epoxidized natural rubber (ENR), deproteinized natural rubber (DPNR), hydrogenated natural rubber, styrene butadiene rubber (SBR), modified styrene butadiene rubber, butadiene rubber (BR), modified butadiene rubber, chlorosulfonated polyethylene rubber, epichlorohydrin rubber, fluorine rubber, nitrile rubber, hydrogenated nitrile rubber, nitrile butadiene rubber (NBR), modified nitrile butadiene rubber, chlorinated polyethylene rubber, styrene ethylene butylenes styrene (SEBS) rubber, ethylene propylene rubber, ethylene propylenediene (EPDM) rubber, Hypalon rubber, chloroprene rubber, ethylene vinylacetate rubber, acrylic rubber, hydrin rubber, vinyl benzyl chloride styrene butadiene rubber, bromomethyl styrene butyl rubber, maleic acid styrene butadiene rubber, carboxylic acid styrene butadiene rubber, epoxy isoprene rubber, maleic acid ethylene propylene rubber, carboxylic acid nitrile butadiene rubber, brominated polyisobutyl isoprene-co-paramethylstyrene (BIMS), and mixtures thereof.
3. The elastomeric nanocomposite reinforced with dual filler composition as claimed in claim 1, wherein the elastomeric compound comprises of solution polymerized styrene butadiene rubber, polybutadiene rubber, and natural rubber in a weight ratio of 60:20:20.

4. The elastomeric nanocomposite reinforced with dual filler composition as claimed in claim 3, wherein the styrene- butadiene rubber may be but not limited to terminally di-functionalized with an alkoxysilane group and a primary amine group.

5. The elastomeric nanocomposite reinforced with dual filler composition as claimed in claim 3, wherein natural rubber has a mooney viscosity 78 ML(1+4) @100 °C.

6. The elastomeric nanocomposite reinforced with dual filler composition as claimed in claim 1, wherein said vulcanization agent is sulfur.

7. The elastomeric nanocomposite reinforced with dual filler composition as claimed in claim 1, wherein said coupling agent is Bis(triethoxysilylpropyl) disulphide.

8. The elastomeric nanocomposite reinforced with dual filler composition as claimed in claim 1, wherein vulcanization activators comprises of zinc oxide and stearic acid in a weight ratio of 3 : 1.50.

9. The elastomeric nanocomposite reinforced with dual filler composition as claimed in claim 1, wherein anti-degradants comprises of 6PPD – N-(1,3-Dimethylbutyl)-N’-phenyl-p-phenylenediamine and Microcrystalline wax (MC wax) in a weight ratio of 1 : 1.

10. The elastomeric nanocomposite reinforced with dual filler composition as claimed in claim 1, wherein anti-aging additive is TMQ (2,2,4-Trimethyl-1,2-hydroquinoline) polymer.

11. The elastomeric nanocomposite reinforced with dual filler composition as claimed in claim 1, wherein the cure accelerators comprises of N-cyclohexyl-2-benzothiazolesulfenamide and Diphenyl guanidine in a weight ratio of 1 : 0.20.

12. The elastomeric nanocomposite reinforced with dual filler composition as claimed in claim 1, wherein the processing aid is selected from general TDAE (Treated distilled aromatic extract) grade oils.

13. The elastomeric nanocomposite reinforced with dual filler composition as claimed in claim 1, wherein the nanocomposite when compounded has a mooney viscosity value in the range between 67-72 ML at a temperature of 125°C and ratio of CB:FE in the range of 3:7-1:1.

14. A tyre comprising an elastomeric nanocomposite reinforced with dual filler composition as claimed in claim 1, in a tread portion.

15. The method of preparation of an elastomeric nanocomposite reinforced with dual filler composition, comprising of the steps:
Preparation of master batch by:
mastication of one or more elastomers for 35 – 45 seconds;
mixing of masticated elastomers with dual filler composition comprising 10 – 70 phr fuller’s earth nano clay and 30 – 90 phr primary filler carbon black, additives and processing oil;
addition of processing aid and mixing for a time period range between 295 – 305 seconds followed by sweeping off the chemicals from the chamber walls and again mixing for a time period of 85-95 seconds to yield master batch; and
dumping the rubber nanocomposite at 160°C,
preparation of final batch by
warming of master batch for 40-50 seconds followed by mixing with cure chemicals and accelerators for 115 – 125 seconds, and
dumping at a temperature range of 108-112°C.

16. The method of preparation of an elastomeric nanocomposite reinforced with dual filler composition as claimed in claim 16, wherein additives comprises of 1.20 – 3 phr coupling agent – Bis(triethoxy silylpropyl)disulphide, 1.50 – 4.50 phr vulcanization activators comprising zinc oxide and stearic acid, 1- 2 phr anti-degradants comprising 6PPD – N-(1,3-Dimethylbutyl)-N’-phenyl-p-phenylenediamine and Microcrystalline wax (MC wax), 1 phr anti-aging additive TMQ (2,2,4-Trimethyl-1,2-hydroquinoline) polymer, 3.10 phr vulcanization agent Sulphur, 0.20 – 1.20 phr cure accelerators comprising N-cyclohexyl-2-benzothiazolesulfenamide and Diphenyl guanidine.

17. The method of preparation of an elastomeric nanocomposite reinforced with dual filler composition as claimed in claim 16, wherein the processing parameters for master batch preparation are rotor speed 43-47 rpm, rotor temperature range of 53 – 57 °C chamber temperature 48 – 52 °C ram pressure is 4.95 -5.05kp/cm2 and fill factor of chamber is 0.88 - 0.92.

18. The method of preparation of an elastomeric nanocomposite reinforced with dual filler composition as claimed in claim 16, wherein the processing parameters for final batch preparation are rotor speed of 28-32 rpm, initial temperature of mixing is 38-42°C.

19. The method of preparation of an elastomeric nanocomposite reinforced with dual filler composition as claimed in claim 15, wherein the composite has a cure time of
7 – 9 minutes at 160°C.

20. The method of preparation of an elastomeric nanocomposite reinforced with dual filler composition as claimed in claim 15, wherein the process is carried out using any one of plastic order, intermix, banbury, two roll mill and the like.

21. The elastomeric nanocomposite reinforced with dual filler composition as claimed in claim 1, wherein the nanocomposite offers superior processing characteristics

22. The elastomeric nanocomposite reinforced with dual filler composition as claimed in claim 1, wherein the cured nanocomposite imparts excellent wet grip. , Description:FIELD OF THE INVENTION:
The present invention relates to the field of tyres and elastomeric compositions in the field of tyres. More particularly, it relates to un-modified fuller’s earth nanoclay and carbon black reinforced elastomeric nanocomposite. Advantageously, the present invention relates to an elastomeric nanocomposite of excellent wet grip and superior processing characteristics and the process of preparation thereof.

BACKGROUND OF THE INVENTION:
Conventionally in cured elastomer(s)-carbon black composites precipitated silica-carbon black dual filler compounds have been used. Few reports have used cured elastomer(s)-carbon black composites with organically modified clay.

US4522970 relates to a pneumatic tire with sulfur cured rubber tread composition containing a medium vinyl polybutadiene rubber and at least one rubber selected from cis 1,4-polyisoprene rubber, styrene/butadiene copolymer rubber and cis 1,3-polybutadiene rubber. The composition also contains both carbon black and clay reinforcement in conjunction with a 3,3'-bis(trimethoxysilylpropyl) polysulfide.

US7220794B2 relates to a rubber composition for tire treads which significantly improves the wet skid performance of the tire, which comprises (A) 100 parts by weight of a diene rubber containing at least 35% by weight of styrene-butadiene rubber, (B) 5 to 50 parts by weight of clay, (C) at least 5 parts by weight of silica having a nitrogen absorption specific surface area of 100 to 300 m.sup.2/g and (D) at least 1 parts by weight of carbon black having a nitrogen absorption specific surface area of 70 to 300 m.sup.2/g, wherein, the total amount of (B) clay and (C) silica is at least 30 parts by weight and a total amount of (B) clay, (C) silica and (D) carbon black is at most 100 parts by weight.

WO2018118855A1 relates to elastomeric compositions comprising at least one polyindane resin. The elastomeric composition of the invention can comprise one or more fillers. The fillers can comprise any filler that can improve the thermo physical properties of the elastomeric composition (e.g., modulus, strength, and expansion coefficient). For example, the fillers can comprise silica, carbon black, clay, alumina, talc, mica, discontinuous fibers including cellulose fibers and glass fibers, aluminum silicate, aluminum trihydrate, barites, feldspar, nepheline, antimony oxide, calcium carbonate, kaolin, and combinations thereof. In one or more embodiments, the fillers comprise an inorganic and nonpolymeric material, the acid-activated clay catalyst may include naturally occurring clay mineral such as kaolinite, bentonite, attapulgite, montmorillonite, clarite, Fuller's earth, hectorite, or beidellite.

US20180291181 relates to polar silane linkers that attach to resins to form silane-functionalized resins. The composition comprises one or more fillers, such as, but not limited to, carbon black, calcium carbonate, clay and other silicates, titanium oxide, and zinc oxide. In another embodiment of the described compositions, the compositions comprise at least about 10, 20, 30, or about 40 and/or not more than about 90, 80, 70, or about 55 weight percent of at least one filler. In another embodiment of the compositions, the composition comprises one or more fillers, such as, but not limited to, carbon black, calcium carbonate, clay and other silicates, titanium oxide, and zinc oxide.

KR100902392 relates to a bead wire coated rubber composition having improved adhesion, and more particularly, to a bead wire coated rubber composition having a lime saturation factor (LSF) of 93 to 95% and a siliceous modulus 2.5 to 2.5%, and Iron Modulus (IM) of 1.4 to 1.7%. The bead wire coating rubber composition further comprises any one 30~95 parts by weight selected from the group consisting of carbon black, syndiotactic-1,2-polybutadiene, silica, titanium dioxide, clay, layered silicate and tungsten.

EP2607098B1 relates to a pneumatic tire with a component containing syndiotactic polybutadiene. The invention particularly relates to a tire with a tread configured with an outer cap rubber layer and an inner or internal underlying rubber layer where the underlying rubber layer comprises such syndiotactic polybutadiene-containing rubber composition. The filler reinforcement comprising at least the carbon black and silica may optionally additionally contain at least one of the platelets of exfoliated clay in an amount of up to 10 phr and the clay (unexfoliated clay) in an amount of up to 40 phr.

The book entitled “Advances in Elastomers-II: Their Composites and Nanocomposites’’ summarizes many of the recent technical research accomplishments in the area of elastomer-based composites and nanocomposites. Recent advances in the development and characterization of multi component polymer composites and nanocomposites based on elastomers are discussed in detail. It is found that 6 phr nano clay has exhibited equivalent reinforcement to that of 40 phr carbon loaded composite with lower heat generation and better dynamic properties. Other nano-fillers such as nano silica, nano carbon black; carbon nano fiber; MWCNT’S, clay and POSS [41] are also applied in tyre industry [P. M. Visakh, Sabu Thomas, Arup K. Chandra, Aji. P. Mathew; Advanced Structured Materials; Volume 12, 2013].

In view of the above prior arts, current invention aims to partially replace the carbon black with naturally available fuller’s earth clay to reduce the production of petroleum originated carbon black and thus helping in reducing the atmospheric pollution and global warming.
Hence, the present invention aims to provide development of un-modified fuller’s earth nanoclay-carbon black reinforced elastomeric nanocomposite that gives excellent wet grip and superior processing characteristics for the tire tread.

OBJECTS OF THE INVENTION:
It is the primary object of the present invention to provide an elastomeric nanocomposite imparting excellent wet grip and superior processing characteristics to tyres.

It is the principal object of the present invention to provide development of un-modified fuller’s earth nanoclay - carbon black reinforced elastomeric nanocomposite.

It is another object of the present invention to partially replace the carbon black with naturally available fuller’s earth nanoclay.

It is another object of the present invention to use environment friendly inorganic filler as an alternative for the conventional carbon black.

It is another object of the present invention to provide application of the elastomeric composite of the invention in tyre and non-tyre products.

SUMMARY OF THE INVENTION:
Thus according to the present invention, there is provided an elastomeric nanocomposite reinforced with dual filler composition, comprising
one or more elastomeric compounds – 100 parts by weight;
dual filler composition comprising chemically un-modified Fuller’s Earth (FE) nanoclay – 10 – 70 phr and primary filler 30 – 90 phr; and
additives,
wherein the additives comprises of vulcanization agent – 3 - 10 phr; coupling agent – 1.20 – 3 phr, vulcanization activators – 1.50 – 4.50 phr, anti-degradants – 1- 2 phr, anti-aging additives – 0.5 – 1 phr; cure accelerators – 0.20 – 1.20 phr; and processing aid / oil comprising general TDAE (Treated distilled aromatic extract) grade oils.
wherein the filler composition for reinforcement comprises chemically unmodified fuller’s earth nanoclay preferably acicular in structure having a length between range 10 and 5000 nanometer with diameter range between 1 and 30 nanometer and carbon black as primary filler.

It is another aspect of the present invention to provide an elastomeric nanocomposite reinforced with dual filler composition, wherein the elastomeric compounds is selected from one or more of natural rubber, epoxidized natural rubber (ENR), deproteinized natural rubber (DPNR), hydrogenated natural rubber, styrene butadiene rubber (SBR), modified styrene butadiene rubber, butadiene rubber (BR), modified butadiene rubber, chlorosulfonated polyethylene rubber, epichlorohydrin rubber, fluorine rubber, nitrile rubber, hydrogenated nitrile rubber, nitrile butadiene rubber (NBR), modified nitrile butadiene rubber, chlorinated polyethylene rubber, styrene ethylene butylenes styrene (SEBS) rubber, ethylene propylene rubber, ethylene propylenediene (EPDM) rubber, Hypalon rubber, chloroprene rubber, ethylene vinylacetate rubber, acrylic rubber, hydrin rubber, vinyl benzyl chloride styrene butadiene rubber, bromomethyl styrene butyl rubber, maleic acid styrene butadiene rubber, carboxylic acid styrene butadiene rubber, epoxy isoprene rubber, maleic acid ethylene propylene rubber, carboxylic acid nitrile butadiene rubber, brominated polyisobutyl isoprene-co-paramethylstyrene (BIMS), and mixtures thereof.

It is another aspect of the present invention to provide an elastomeric nanocomposite reinforced with dual filler composition, wherein the elastomeric compound comprises of solution polymerized styrene butadiene rubber, poly butadiene rubber, and natural rubber in a weight ratio of 60:20:20.

It is another aspect of the present invention to provide an elastomeric nanocomposite reinforced with dual filler composition, wherein the styrene butadiene rubber may be but not limited to terminally di-functionalized with an alkoxysilane group and a primary amine group.

It is another aspect of the present invention to provide an elastomeric nanocomposite reinforced with dual filler composition, wherein natural rubber having mooney viscosity 78 ML(1+4)@100°C.

It is another aspect of the present invention to provide an elastomeric nanocomposite reinforced with dual filler composition, wherein the vulcanization agent is sulfur.

It is another aspect of the present invention to provide an elastomeric nanocomposite reinforced with dual filler composition, wherein the coupling agent is Bis(triethoxysilylpropyl)disulphide.

It is another aspect of the present invention to provide an elastomeric nanocomposite reinforced with dual filler composition, wherein vulcanization activators comprises of zinc oxide and stearic acid in a weight ratio of 3:1.50.

It is another aspect of the present invention to provide an elastomeric nanocomposite reinforced with dual filler composition, wherein anti-degradants comprises of 6PPD-N-(1,3-Dimethylbutyl)-N’-phenyl-p-phenylenediamine and Microcrystalline wax (MC wax) in a weight ratio of 1:1.
It is another aspect of the present invention to provide an elastomeric nanocomposite reinforced with dual filler composition, wherein anti-aging additive is TMQ (2,2,4-Trimethyl-1,2-hydroquionoline) polymer.

It is another aspect of the present invention to provide an elastomeric nanocomposite reinforced with dual filler composition, wherein the cure accelerators comprises of N-cyclohexyl-2-benzothiazolesulfenamide and Diphenyl guanidine in a weight ratio of 1: 0.20.

It is another aspect of the present invention to provide an elastomeric nanocomposite reinforced with dual filler composition, wherein the nanocomposite when compounded has a mooney viscosity value in the range between 67 – 72 ML at a temperature of 125°C and ratio of CB: FE in the range of 3 : 7 – 1 : 1.

It is another aspect of the present invention to provide tyre comprising an elastomeric nanocomposite reinforced with dual filler composition comprising un-modified fuller’s earth nanoclay and primary filler as carbon black, in a tread portion.

It is another aspect of the present invention to provide a method of manufacture of an elastomeric nanocomposite reinforced with dual filler composition, comprising of the steps:
Preparation of master batch by:
mastication of one or more elastomers for 35 – 45 seconds in a mixer;
mixing of masticated elastomers with dual filler composition comprising 10 – 70 phr fuller’s earth nanoclay and 30 – 90 phr primary filler carbon black, additives and processing oil;
addition of processing aid/ oil and mixing for a time period range between 295 – 305 seconds followed by sweeping off the chemicals from the chamber walls and again mixing for a time period of 85 – 95 seconds to yield master batch; and
dumping the rubber nanocomposite at 160°C,
preparation of final batch by
warming of master batch for 40 – 50 seconds followed by mixing with cure chemicals and accelerators for 115 – 125 seconds and
dumping at a temperature range of 108 – 112 °C.

It is another aspect of the present invention to provide a method of manufacture of an elastomeric nanocomposite reinforced with dual filler composition, wherein additives comprises of 1.20 – 3 phr coupling agent – Bis(triethoxy silyl propyl) disulphide, 1.50 – 4.50 phr vulcanization activators comprising zinc oxide and stearic acid, 1 – 2 phr anti-degradants comprising 6PPD-N-(1,3-Dimethylbutyl)-N’-phenyl-p-phenylene diamine and Microcrystalline wax (MS wax), 0.5 - 1 phr anti-aging additive TMQ (2,2,4-Trimethyl-1,2-hydroquinoline) polymer, 3 – 10 phr vulcanization agent sulphur, 0.20 – 1.20 phr cure accelerators comprising N-cyclohexyl-2-benzothiazolesulfenamide and Diphenyl guanidine.

It is another aspect of the present invention to provide a method of manufacture of elastomeric nanocomposite reinforced with dual filler composition, wherein the processing parameters for master batch preparation are rotor speed 43 – 47 rpm, rotor temperature range of 53 – 57 °C, chamber temperature 48 – 52 °C, ram pressure is 4.95 – 5.05 kp/cm2 and fill factor of chamber is 0.88 – 0.92.

It is another aspect of the present invention to provide a method of manufacture of elastomeric nanocomposite reinforced with dual filler composition, wherein the processing parameters for final batch preparation are rotor speed of 28 – 32 rpm, initial temperature of mixing is 38 – 42 °C.
It is another aspect of the present invention to provide a process of manufacture of elastomeric nanocomposite reinforced with dual filler composition, wherein the composite has a cure time of 7 – 9 minutes at 160 °C.

It is another aspect of the present invention to provide a method of an elastomeric nanocomposite reinforced with dual filler composition, wherein the process is carried out using one of plasticoder, intermix, banbury, two-roll mill and the like.

BRIEF DESCRIPTION OF DRAWINGS:
The annexed drawings show an embodiment of the present invention, wherein
Figure 1 illustrates the cure time of compounds claiming in present invention (Control, CB/FE-35/15, CB/FE-25/25, CB/FE-15/15).
Figure 2 illustrates the cure time of compounds used as reference in present invention (CB/Si – 35/15, CB/Si – 25/25, CB/Si – 15/15).
Figure 3 illustrates the Mooney viscosity of the compounds claiming in present invention (Control, CB/FE -35/15, CB/FE – 25/25, CB/FE -15/15).
Figure 4 illustrates the Mooney viscosity of compounds used as reference in present invention (CB/Si -35/15, CB/Si- 25/25, CB/Si – 15/15).
Figure 5 illustrates the tan d values of compounds claiming in present invention (Control, CB/FE – 35/15, CB/FE-25/25, CB/FE -15/15).
Figure 6 illustrates the tan d values of compounds used as reference in present invention (CB/Si-35/15, CB/Si-25/25, CB/Si – 15/15).

DETAILED DESCRIPTION OF THE INVENTION ACCOMPANYING FIGURES:
The present invention relates to the field of tyres and elastomeric compositions capable of providing products with excellent wet grip and superior processing characteristics.
In accordance with the present invention, there is provided an elastomeric nanocomposite composition comprising of reinforcing dual filler composition comprising of chemically un-modified fuller’s earth nanoclay and primary filler -carbon black. The developed nanocomposite has good processing characteristics (lower mooney viscosity) as compared with conventional carbon black-silica based dual filler composition. It thereby reduces the tear and wear of the process equipment viz rubber mixer, tread extruder, etc.

In accordance with the present invention, there is provided an elastomeric nanocomposite composition also containing elastomeric compounds selected from one or more of natural rubber, epoxidized natural rubber (ENR), deproteinized natural rubber (DPNR), hydrogenated natural rubber, styrene butadiene rubber (SBR), modified styrene butadiene rubber, butadiene rubber (BR), modified butadiene rubber, chlorosulfonated polyethylene rubber, epichlorohydrin rubber, fluorine rubber, nitrile rubber, hydrogenated nitrile rubber, nitrile butadiene rubber (NBR), modified nitrile butadiene rubber, chlorinated polyethylene rubber, styrene ethylene butylenes styrene (SEBS) rubber, ethylene propylene rubber, ethylene propylenediene (EPDM) rubber, Hypalon rubber, chloroprene rubber, ethylene vinylacetate rubber, acrylic rubber, hydrin rubber, vinyl benzyl chloride styrene butadiene rubber, bromomethyl styrene butyl rubber, maleic acid styrene butadiene rubber, carboxylic acid styrene butadiene rubber, epoxy isoprene rubber, maleic acid ethylene propylene rubber, carboxylic acid nitrile butadiene rubber, brominated polyisobutyl isoprene-co-paramethylstyrene (BIMS), and mixtures thereof; vulcanization agent sulfur; coupling agent as Bis(triethoxysilylpropyl)disulphide; vulcanization activators comprising of zinc oxide and stearic acid; anti-degradants comprising of 6PPD – N-(1,3-Dimethylbutyl)-N’-phenyl-p-phenylenediamine and Microcrystalline wax (MC wax); anti-aging additive as TMQ (2,2,4-Trimethyl-1,2-hydroquinoline)polymer; and cure accelerators comprises of N-cyclohexyl-2-benzothiazolesulfenamide and diphenyl guanidine.
In accordance with the present invention, there is an elastomeric nanocomposite composition which consists of elastomer(s) 100 by weight, fuller’s earth nanoclay preferably acicular in structure having a length of 10 nm to 5000 nm and without any organic modification 10 – 70 parts by weight, carbon black 30 – 90 parts by weight and a rubber composition consisting of conventional additives and mixing procedure thereof.

An elastomeric nanocomposite composition, according to an embodiment of the present invention, which can be used to produce products with excellent wet grip and with superior processing characteristics, consists of 100 parts by weight of elastomeric compounds, comprising 60 parts by weight of solution polymerized styrene-butadiene rubber terminally di-fuctionalized with an alkoxysilane group and a primary amine group, 20 parts by weight of polybutadiene rubber or simply butadiene rubber having 96% cis-1,4 configuration and mooney viscosity 45 ML(1+4) @100°C, and 20 parts by weight of natural rubber having mooney viscosity 78ML(1+4)@100°C; a dual filler composition comprising of 10 – 70 parts by weight of fuller’s earth nanoclay and 30 – 90 parts by weight of carbon black. Preferred embodiments may comprise of any grades of solution polymerized styrene butadiene rubber (S SBR).

The elastomeric nanocomposite, according to an embodiment of the present invention, also consists of 3 – 10 phr of vulcanization agent as Sulphur, coupling agent as Bis(triethoxy silylpropyl)disulphide – 1.20 – 3 phr; vulcanization activators – 1.50 – 4.50 phr comprising zinc oxide and stearic acid preferably in a weight ratio of 3:1.50; anti-degradants 1-2 phr comprising 6PPD – N-(1,3-dimethylbutyl)-N’-phenyl-p-phenylenediamine and microcrystalline wax (MC wax); anti-aging additives as TMQ (2,2,4-Trimethyl-1,2-hydroquinoline) polymer 0.5 - 1 phr ; cure accelerators 0.20 – 1.20 phr comprising N-cyclohexyl-2-benzothi azolesulfenamide and diphenyl guanidine preferably in a weight ratio of 1:0.20; processing aid.
Method of preparation of an elastomeric nanocomposite reinforced with dual filler composition:
An embodiment of the present invention discloses a method of preparation of an elastomeric nanocomposite comprising of dual filler composition comprising a chemically un-modified fuller’s earth nanoclay and primary filler as carbon black.
The steps comprises of:
The process can be carried out using one of plasticoder, intermix, banbury, two-roll mill and the like.
To demonstrate, the process is carried out using a banbury mixer.
A) Method of preparation of master batch comprising of the steps:
The ingredients are initially mixed in an internal mixture. The rotor speed is maintained constantly around 43 - 47 rpm. The temperature of rotor of the internal mixer is maintained around 53 - 57°C and the temperature of the chamber of the internal mixer is maintained around 48 - 52°C. The ram pressure is kept to 4.95 - 5.05 kp/cm2. The batch weight is decided based in the chamber volume of the mixer. The fill factor of the chamber is 0.88 – 0.92. The total mixing time of the master batch compound is around 7 minutes.

Rubber (elastomers) is initially masticated for 35 - 45 minutes. The rubber chemicals, unmodified fuller’s earth nanoclay and processing oil / aid is added to the masticated rubber. Further, the chemicals are added in the following order: cure activators, anti-degradants. The initial addition of fuller’s earth nanoclay helps in the fine dispersion of the nano material into the rubber matrix. This mixing process is carried out for295 - 305 seconds. This is followed by sweeping off the chemicals from the chamber walls and again the mixing is continued up to 85 - 95 seconds. Finally, the mixed rubber nanocomposite is dumped. The dump temperature of the rubber nanocomposite is 160°C.

The rubber chemicals are coupling agent Bis(triethoxysilylpropyl)disulphide, vulcanization activators as zinc oxide and stearic acid, anti-degradants as 6PPD –N-(1,3-Dimethylbutyl)-N’-phenyl-p-phenylenediamine and Microcrystalline wax, anti-aging additive as TMQ (2,2,4-Trimethyl-1,2-hydroquinoline)polymer, vulcanization agent sulphur, cure accelerators as N-cyclohexyl-2-benzothiazolesulfenamide and Diphenyl guanidine and dual filler composition comprising unmodified fuller’s earth nanoclay and primary filler as carbon black.

B) Method of preparation of final batch comprising of the steps:
Rotor speed is maintained at 28 – 32 rpm and the starting temperature of mixing is
38 - 42°C. The ram pressure is kept to 5 kp/cm2. The master batch is warmed for 40 - 50 seconds. The cure chemical and accelerator were added further and mixed for 115 - 125 seconds. The dump temperature is kept at 108 – 112 °C.

The main parameters which decide the ease of processing of an elastomeric composite are viscosity and curing of the respective composites. If the mooney viscosity of a compound is high, for processing that compound, one needs to apply more shear force which leads to more power usage and ultimately cost of production also get increases. Similarly, the cure time is the time required to keep the elastomeric composite under prescribed cure temperature and pressure for getting cross-linked with the added curatives. If the cure time is high for an elastomeric composite, the time required for producing a product using that composite will also increase which will lead to low production output.

Example 1:
The present invention will be explained further by examples, but the scope of the present invention is, not limited to these examples.
A set of four (4) compounds is designed as shown in Table 1. The control compound is designed in such a way that there is no filler is used to reinforce the Solution Polymerized Styrene-butadiene rubber (SSBR)/ Butadiene Rubber (BR)/ Natural rubber (NR) Tri-blend. The other compounds contain carbon black and fuller’s earth nanoclay without any chemical modification as a dual filler system for reinforcement.

Table 1:
Designation
Ingredient Control CB/FE-35/15 CB/FE-/25/25 CB/FE-15/35
HPR 3551 60.00 60.00 60.00 60.00
ISNR 202 20.00 20.00 20.00 20.00
BR3 20.00 20.00 20.00 20.00
FE4 0.00 15.00 25.00 35.00
Carbon Black5 0.00 35.00 25.00 15.00
SI-756 1.20 2.00 2.80
ZnO 3.00 3.00 3.00 3.00
Stearic acid 1.50 1.50 1.50 1.50
6PPD7 1.00 1.00 1.00 1.00
TMQ8 1.00 1.00 1.00 1.00
MC-wax9 1.00 1.00 1.00 1.00
Sulphur 3.10 3.10 3.10 3.10
CBS10 1.00 1.00 1.00 1.00
DPG11 0.20 0.20 0.20 0.20
Total 111.80 163.00 163.80 164.60

[1] Solution polymerized styrene-butadiene rubber terminally di-functionalized with an alkoxysilane group and a primary amine group from Japan Synthetic Rubber (JSR).
[2] Indian standard natural rubber grade 20 having Mooney viscosity 78 ML (1+4) @ 100°C
[3] Polybutadiene Rubber or simply Butadiene Rubber from Relflex elastomers CISAMER PBR 1220, Cobalt (Co) Catalyst, Cis-1, 4 Configuration (%)96, Mooney Viscosity ML (1+4) @ 100 °C, MU 45
[4] Fuller’s earth nanoclay having a length between 1-5000 nanometer and diameter of 1-30 nano meter without any chemical modification
[5] ASTM nomenclature N339 grade carbon black – The primary filler
[6] Bis(triethoxysilylpropyl)disulphide- the chemical which acts as a coupling agent between the silanol (Si-OH) group on the FE clay surface and the rubber polymer chain to improve filler-polymer interaction
[7] N-(1,3-dimethylbutyl)-N’-phenyl-p-phenylenediamine.- an anti-aging additive used to prevent oxidative and ozone degradation of rubber polymer chains
[8] 2,2,4-Trimethyl-1,2-Dihydroquinoline polymer- an anti-aging additive used to prevent oxidative and ozone degradation of rubber polymer chains
[9] Microcrystalline wax- the wax used to prevent the ozone degradation of rubber polymer chains in static conditions.
[10] N-cyclohexyl-2-benzothiazolesulfenamide –a chemical which accelerates the rate of crosslinking reaction between sulfur and rubber polymer chain.
[11]Diphenyl guanidine- a chemical which accelerates the rate of crosslinking reaction between sulfur and rubber polymer chain

The present invention discloses a set of compound formulations in which a dual filler system of carbon black and FE nano-clay is used to reinforce a tri-blend system of rubbers, the said rubbers are
a) Solution polymerized styrene-butadiene rubber terminally di-functionalized with an alkoxysilane group and a primary amine group
b) Indian standard natural rubber grade 20
c) Polybutadiene Rubber or simply Butadiene Rubber

Another set of reference compounds designed as shown in Table 2, in which the SSBR/BR/NR tri-blend has been reinforced using conventionally available carbon black – silica dual filler system to compare the processing parameters of the current invention with conventional carbon black – silica dual filler system.

Table 2: Reference compound formulations
Ingredients Designations
CB/Si-35/15 CB/Si-25/25 CB/Si-15/35
HPR 355 60.00 60.00 60.00
ISNR 20 20.00 20.00 20.00
BR 20.00 20.00 20.00
Carbon Black 35.00 25.00 15.00
Silica12 15.00 25.00 35.00
SI-75 1.20 2.00 2.80
ZnO 3.00 3.00 3.00
Stearic acid 1.50 1.50 1.50
6PPD 1.00 1.00 1.00
TMQ 1.00 1.00 1.00
MC-wax 1.00 1.00 1.00
Sulfur 3.10 3.10 3.10
CBS 1.00 1.00 1.00
DPG 0.20 0.20 0.20
Total 163.00 163.80 164.60

[12]Ultrasil VN3 silica from Evonik Industries, Germany.

Results
The cure behaviour of all the compounds has been measured in accordance with the ASTM standard D 1646-04 at 160°C using an Oscillating disc rheometer (model:EKT-100H, Ektron Tek Co. Ltd.Taiwan ). The control compound has recorded a curing time of 10 minutes 18 seconds at 160°C. In present invention the compound CB/FE-25/25 has shown a cure time of 7 – 9 minutes (i.e. appropriately 8 minutes 54 seconds) at 160°C as shown in Figure 1 and Table 3, while the conventional compound CB/Si-25/25 is having a cure time of 13 minutes 36 seconds at 160°C as shown in Figure 2, Table 4. The compounds according to the present invention are showing lower cure time as compared to the reference compounds (Figure 2) (Table 4). In comparison with the reference compounds, the present invention offers curing process benefits. The Mooney viscosity of the compounds was measured in accordance with the ASTM standard D 1646-04 at 125°C using a Mooney viscometer (model: Mooney MV-2000, Alpha Technologies, Ohio, USA).

Table 3: Processing parameters of proposed compounds
Compound Control CB/FE-35/15 CB/FE-25/25 CB/FE-15/35
Cure Time @160°C (Minutes:Seconds) 10:18 08:55 08:54 11:33
Mooney viscosity
(ML(1+4)@125°C) 30 69.1 71.2 67.2
Scorch Time @125°C (Minutes:Seconds) 42:37 25:37 27:42 31:01

Table 4: Processing parameters of reference compounds
Compound CB/Si-35/15 CB/Si-25/25 CB/Si-15/35
Cure Time @160°C (Minutes:Seconds) 11:29 13:36 17:44
Mooney viscosity
(ML(1+4)@125°C) 81 72.2 85.4
Scorch Time @125°C (Minutes:Seconds) 29:24 40:01 42:36

The Mooney viscosity values are expressed as X ML(1+4) at 125°C where X is the Mooney viscosity values, M indicates that the unit is in Mooney scale, L stands for the rotor size, L is for large rotor, 1 is the rotor pre-heating time in minutes,4 is the test duration in minutes and 125°C is the test temperature. The control compound has recorded a mooney viscosity of 30 ML(1+4) at 125°C, which is the base Mooney viscosity value for the SSBR/BR/NR tri blend without any reinforcements. CB/FE-35/15 has Mooney viscosity 69.1 ML(1+4) at 125°C (Figure 3.,Table 3.) CB/Si-35/15 were the corresponding reference compound has 81ML(1+4) at 125°C (Figure 4, Table 4). Hence the FE based compounds offer processing benefits over the conventional compounds.

Mooney viscosity and the cure time are the parameter which decides the ease of processing of an elastomeric compound. Since the present invention offers a lower mooney viscosity and cure time than the reference compounds it exhibits better processing characteristics than the reference compounds. The scorch time is another major processing parameter for rubber vulcanisates which determines the extent of safe processing before the vulcanization of the compound. The present invention offers a minimum scorch time of atleast 25 minutes and 37 seconds for CB/FE-35/15 and a maximum of 31 minutes for the CB/FE-15/35 at 125°C which is sufficient for shaping complex articles such as tires.

The dynamic mechanical analysis of the compounds has been done in temperature sweep mode from -100°C to +60°C at 20Hz frequency with a dynamic strain of 0.1% using a dynamic mechanical analyzer (DMA) (model: DMA+1000, Metravib, Limonest, France) to obtain the tan d values at 0°C. The tan d value at 0°C is conventionally taken as an authentic measure for predicting the wet grip of the tyre tread compound. The CB/FE-25/25 shown a tan d value at 0°C of 0.581 in Figure 5, Table 5. The conventional reference compound CB/Si-25/25 is showing only 0.568 (Figure 6, Table 6) which implicates that the compound CB/FE-25/25 offers good wet grip than the reference compound (CB/Si-25/25).

Table 5: Tan d values of compounds
Compound Tan d @ 0°C
Control 0.541
CB/FE-35/15 0.534
CB/FE-/25/25 0.581
CB/FE-15/35 0.515

Table 6: Tan d values of reference compounds
Compound Tan d @0°C
CB/Si-35/15 0.554
CB/Si-25/25 0.568
CB/Si-15/35 0.569

In reference to Table 5, Tan delta increases with the increase in concentration of FE up to 25 phr and beyond which the tan delta value starts to decrease. Therefore, it is evident that the CB/FE (25/25) is an optimum concentration to achieve enhanced tan delta value for a better wet grip performance. At very high concentration of FE (35 phr), the nanoparticles will have tendency to form aggregation/agglomeration, which will generate topological constraints for the mobility of rubber chains. This topological constraints for mobility of rubber chains will tend to increase the elastic modulus and subsequently the tan delta value starts to decrease. Hence the optimum concentration of CB/FE is 25/25.

Advantages:
1. The wet grip of the unmodified fuller’s earth nanoclay – carbon black reinforced elastomeric compound is better than the conventional carbon black filled elastomeric composites.
2. The resultant elastomeric composite it can be effectively employed in the motor cycle tire tread having excellent wet grip.
3. Since the present invention is offering easy processability than the conventional precipitated silica-carbon black dual filler compounds, the energy consumption is getting reduced and productivity increases.
4. By partially replacing the carbon black with naturally available fuller’s earth clay reduces the production of petroleum originated carbon black and thus helping in reducing the atmospheric pollution and global warming.