DESC:FIELD OF THE INVENTION:
The present invention relates to the field of tyre bead insulation. The present invention relates particularly to elastomeric nanocomposites suitable for bead insulation. More importantly, the present invention relates to a rubber nanocomposite using organically modified nanoclay as one of the fillers that imparts high stiffness, improved mechanical properties and low gas permeability.

BACKGROUND OF THE INVENTION:
The existence of rubber nanocomposites and its potential applications are well known. However, very less works has been carried out in extracting the functional properties of nanofillers for motorcycle tyre applications. Albeit, literatures and patents were available in motorcycle tread compounds, exploration of effect of nanofillers in motorcycle tyre bead still remains scarce.

Tyre as a whole is a composite structure and each component of the tyre has its own application and pivotal role to play. Integrity and stability of such components are important for high performance tyre. Tyre bead is typically selected for present invention as it transfers the load from ground to the rim during cornering at higher speeds. It also helps in providing riding stability due to its rigid seating on the tyre rim. The development of such high-performance functional rubber nanocomposite as tyre bead insulation caters to the stringent automotive needs.

US6598645 B1 relates to a tyre with at least one component of a rubber composition which contains oriented exfoliated platelets derived from intercalated clay. Such tyre component may be, for example, a rubber/cord laminate and, optionally, a sidewall insert and, optionally, an apex which contain the organoclay, namely the intercalated Montmorillonite clay and exfoliated intercalated Montmorillonite clay. The patent discusses about rubber composition of tyre materials which comprises oriented exfoliated clay platelets and not on properties of the developed nanocomposites.

Indian Publication No. 1915/DELNP/2006 relates to tyre comprising at least one structural element including a cross-linked elastomeric material obtained by crosslinking a cross linkable elastomeric composition comprising: (a) 100 phr of at least one diene elastomeric polymer; (b) from 1 phr to 50 phr, preferably from 2 phr to 40 phr, more preferably from 5 phr to 30 phr, of at least one layered material having an individual layer thickness of from 0.01 nm to 30 nm, preferably of from 0.05 nm to 15 nm; (c) from 0.1 phr to 15 phr, preferably from 0.3 phr to 10 phr, of at least one methylene donor compound; (d) from 0.4 phr to 20 phr, preferably from 0.8 phr to 15 phr, of at least one methylene acceptor compound. The patent explains about a cross linkable elastomeric composition containing layered material as a structural element in tyre.
WO2005042278 A2 relates to tyre comprising at least one structural element including a cross-linked elastomeric material obtained by crosslinking a crosslinkable elastomeric composition containing layered material.

JP2004082785A relates to radial tyre composed of a skeleton of a carcass comprising a carcass main body comprising plies of rubber-coated cords extended in radial directions between a pair of bead cores, and a bent part comprising the plies wound around the bead core from the inside of the tyre outward to be extended radially outward of the tyre. Coating rubber is provided to cover at least terminal parts of the bent parts, and the coating rubber is composed of rubber composition comprising layered clay minerals in organic form blended by 1-30 pts. mass to 100 pts. mass of rubber. The invention discusses about preventing cracking of bead area by use of nanofiller in the turn up region of ply.

Accordingly, the present invention addresses a pertinent need that exists for a rubber nanocomposite using organically modified nanoclay as one of the fillers providing improved stiffness, mechanical properties and low gas permeability and finds application in rubber tyre bead insulation.

OBJECTS OF THE INVENTION;
It is primary object of the present invention to provide a rubber nanocomposite using organically modified nanoclay as filler with high stiffness, improved mechanical properties and low gas impermeability.

It is another object of the present invention to provide a high performance vehicle tyre bead insulation composition using organically modified nanoclay.

It is another object of the present invention to optimize the performance of the pneumatic tyres.

It is another object of the present invention to provide a partial replacement of conventional carbon blacks.

It is another object of the present invention to provide a tyre with the bead insulation of which comprises an elastomeric composition of an emulsion styrene butadiene copolymer (E-SBR) and, optionally recycled rubber (WTR).

It is another object of the present invention to provide a rubber nanocomposite based on styrene butadiene rubber or its blend with natural rubber with organically modified nanoclay that imparts superior mechanical and barrier properties.

SUMMARY OF THE INVENTION:
One or more of the problems of the conventional prior art may be overcome by various embodiments of the present invention.
It is the primary aspect of the present invention to provide a tyre bead comprising,
bead wire; and
bead insulation comprising a rubber nanocomposite and one or more organically modified nanofillers.

It is another aspect of the present invention to provide a rubber nanocomposite for bead insulation, comprising of:
rubber nanocomposite comprising one or more elastomers – 100 phr;
reinforcing fillers comprising carbon black – 50 – 100 phr and precipitated calcium carbonate – 5 – 30 phr;
organically modified nanofiller – 0.5 – 0.15 phr;
processing aid – 1 – 30 phr;
cure activator – 1- 10 phr;
tackifier resin – 1 – 15 phr;
curative – 1- 15 phr;
accelerator – 1- 5 phr; and
anti-degradant – 1- 6 phr,
wherein the nanofiller is organically modified comprising particle size of 0.1 to 10 micrometres and d-spacing of 2.5 to 3.5 nanometres.

It is another aspect of the present invention to provide a rubber nanocomposite for bead insulation, wherein said organically modified nanoclay is Bis(hydrogenated tallow alkyl) dimethyl, salt with bentonite.

It is another aspect of the present invention to provide a rubber nanocomposite for bead insulation, wherein said elastomers comprises of styrene butadiene rubber, reclaim rubber, natural rubber and combinations thereof.

It is another aspect of the present invention to provide a rubber nanocomposite for bead insulation, wherein said elastomers comprises of emulsion of styrene butadiene copolymer (E-SBR) and reclaim rubber (WTR) in a weight ratio of 97 : 6.

It is another aspect of the present invention to provide a rubber nanocomposite for bead insulation, wherein said reinforcing filler comprises of carbon black N550, carbon black N660 and combinations thereof.

It is another aspect of the present invention to provide a rubber nanocomposite for bead insulation, wherein the cure activator is Zinc oxide.
It is another aspect of the present invention to provide a rubber nanocomposite for bead insulation, wherein the tackifier resin comprises of capolyte, hydrocarbon and combinations thereof.

It is another aspect of the present invention to provide a rubber nanocomposite for bead insulation, wherein the curative comprises one of soluble sulphur and insoluble sulphur.

It is another aspect of the present invention to provide a rubber nanocomposite for bead insulation, wherein the processing aid comprises of stearic acid, oils, homogenising aids and combinations thereof.

It is another aspect of the present invention to provide a rubber nanocomposite for bead insulation, wherein the accelerator comprises of N-cyclohexyl benzothiazole sulfenamide (CBS), N-tert-butyl-2-benzothiazyl sulfenamide (TBBS) and combinations thereof.

It is another aspect of the present invention to provide a rubber nanocomposite for bead insulation, wherein the anti-degradant comprises of trimethyl dihydro quinoline (TMQ), para phenylene diamine (PPD), 2,2,4-trimethyl-1,2-dihydroquinoline (TQ) and combinations thereof.
It is another aspect of the present invention to provide a process of preparation of rubber nanocomposite for bead insulation, comprising of steps:
conditioning of a nano filler by subjecting it to an initial pre-drying at a temperature range between 60°C and 80°C in heat aging oven for 12-48 hours to remove all the entrapped moisture;
preparation of master batch by,
initial mixing the ingredients in Banbury mixer;
initial masticating the rubber for 20-60 seconds;
loading of chemicals comprising cure activators, anti degradants, and tackifier resin;
adding of organically modified nanoclay followed by the addition of reinforcing fillers;
mixing for 180 – 250 seconds, sweeping off the chemicals from the chamber walls; again mixing for 80 – 160 seconds; and
dumping of mixed rubber nanocomposite to get the master batch mix;
wherein the rotor speed of the master batch is maintained constantly in the range 50-70 rpm,
wherein the temperature of mixing is maintained around 60-80°C,
wherein the batch weight is decided based in the chamber volume of the mixer, wherein the fill factor of the chamber is 0.70-0.90, and
wherein the total mixing time of the master batch compound is 4-8 minutes, and wherein the dump temperature of the rubber nanocomposite is 145-165°C, and the master batch is subjected to further mixing process to yield the final batch.

It is another aspect of the present invention to provide a process of preparation of rubber nanocomposite for bead insulation, wherein the final batch mixing process, comprising of steps:
Initial warming of master batch for 15-45 seconds; and
adding cure chemical and accelerator to the master batch,
wherein the starting temperature range of mixing is between 30°C and 50°C,
wherein the rotor speed is maintained at 30 - 60 rpm,
wherein the dump temperature range varies between 105°C-120°C.

DETAILED DESCRIPTION OF THE INVENTION:
The present invention relates to the field of tyres and more particularly to rubber nanocomposite composition with organically modified nanoclay for tyre bead applications.

The present invention relates to a rubber nanocomposite based on styrene butadiene rubber or its blend with natural rubber and one or more of organically modified nanoclay that has superior mechanical and barrier properties. The rubber nanocomposites developed have high stiffness, improved mechanical properties and low gas permeability and a process of manufacture of such compounds is provided. Motor cycle tyre bead insulated with the developed nanocomposite has superior stiffness, rigidity and gas impermeability.

In accordance with the present invention there is provided a rubber nanocomposite comprising of one or more of organically modified nanofillers. Particularly the nanofiller is Cloisite 20. Cloisite is bis (hydrogenated tallow alkyl) dimethyl, salt with bentonite. It is off-white in color and has got a typical dry particle size less than 10 micrometers and a d-spacing of 3.16 nm. It comprising particle size of 0.1 to 10 micrometers and d-spacing of 2.5 to 3.5 nanometres.

In accordance with the present invention there is provided a rubber nanocomposite also consists of elastomers selected from one or more of styrene butadiene rubber, reclaim rubber and natural rubber; reinforcing filler comprising carbon black preferably one or more of N550, N660, and precipitated calcium carbonate; processing aid; cure activators; tackifier resin; curative; accelerators and anti-degradants.

In accordance with the present invention the rubber nanocomposite composition preferably consists of stearic acid, oils, homogenizing aids and combinations thereof as processing aids; Zinc oxide as cure activators; capolyte, hydrocarbon and combinations thereof as tackifier resin; one of soluble sulphur and insoluble sulphur as curatives; N-cyclohexyl benzothiazole sulfenamide (CBS) , N-tert-butyl-2-benzothiazyl sulfenamide (TBBS) and combinations thereof as accelerators; and trimethyl dihydro quinoline (TMQ), para phenylene diamine (PPD), 2,2,4-trimethyl-1,2-dihydroquinoline (TQ) and combinations thereof as anti-degradants.
In accordance with the present invention there is provided a rubber nanocomposite which consists of one or more elastomers – 100 phr, 0.5 to 0.15 phr of one or more of organically modified nanofillers.

A rubber nanocomposite according to an embodiment of the present invention, which can be used to produce tyre bead insulation with improved mechanical properties, consists of 100 parts by weight of elastomeric compounds, comprising emulsion of styrene butadiene copolymer (E-SBR) and reclaim rubber (WTR) in a weight ratio of 97 : 6; 0.5 to 0.15 phr of organically modified nanofiller as Bis(hydrogenated tallow alkyl) dimethyl salt with bentonite comprising particle size of 0.1 to 10 micrometers and d-spacing of 2.5 to 3.5 nanometers (Cloisite). The composite comprises of different propositions of Cloiste 20 in addition to carbon black as filler. However, very small dosages of Cloisite 20 can also be used as partial replacement of the carbon black fillers.

A rubber nanocomposite according to an embodiment of the present invention, also consists of reinforcing fillers comprising of carbon black 50 – 100 phr and precipitated calcium carbonate 5 – 30 phr; processing aid – 1-30 phr; cure activator – 1- 10 phr; tackifier resin – 1- 15 phr; curative 1- 15 phr; accelerator 1 – 5 phr; and anti-degradant 1- 6 phr.

Method of preparation of a rubber nanocomposite comprising of one or more of organically modified nanofiller:
An embodiment of the present invention discloses a method of preparation of a rubber nanocomposite comprising of one or more of organically modified nanofiller.
The steps comprises of:

Master batch mixing process
The ingredients are initially mixed in Banbury mixer. The rotor speed is maintained constantly around 50-70 rpm. The temperature of mixing is maintained around 60-80°C. The batch weight is decided based in the chamber volume of the mixer. The fill factor of the chamber is 0.70-0.90. The total mixing time of the master batch compound is around 4-8 minutes. Rubber (SBR+WTR reclaim) is initially masticated for 20-60 seconds. This also ensures effective blending of reclaim with SBR. The chemicals, organically modified nanoclay, fillers and processing oil are added to the masticated rubber. The organically modified nanoclay is subjected to an initial conditioning process, wherein the material is pre-dried in heat aging oven at 60-80°C for 12-48 hours to remove all the entrapped moisture.

Further, the chemicals are loaded in the following order: cure activators, antidegradants, and tackifier resin. The organically modified nanoclay is added next and that is followed by the addition of fillers. The initial addition of organically modified nanoclay helps in fine dispersion of the nanomaterial into the rubber matrix. The mixing process is carried out for 180-250 seconds. This is followed by sweeping off the chemicals from the chamber walls and again the mixing is continued up to 80-160 seconds. Finally the mixed rubber nanocomposite is dumped. The dump temperature of the rubber nanocomposite is 145-165°C.

Final Batch Mixing Process
Rotor speed is maintained at 30-60 rpm and the starting temperature of mixing is 30°C-50°C. The master batch is warmed for 15-45 seconds. The cure chemical and accelerator were added further and mixed for 50-100 seconds. The dump temperature varies between 105°C-120°C.

Example:
The present invention will be explained further by examples, but the scope of the present invention, is not limited to these examples.
Ingredients Control Trial 1 Trial 2
SBR 1500 97.00 97.00 97.00
N660 85.00 85.00 85.00
PPT Calcium Carbonate 25.00 25.00 25.00
Cloisite 20 0.00 5.00 10.00
WTR Reclaim 6.00 6.00 6.00
Low PCA OIL 10.00 10.00 10.00
Zinc Oxide 10.00 10.00 10.00
Stearic Acid 5.00 5.00 5.00
TMQ/RD 1.00 1.00 1.00
6PPD 1.00 1.00 1.00
CP 90 2.00 2.00 2.00
Insoluble Sulphur 10.00 10.00 10.00
CBS 2.00 2.00 2.00
Total 254.00 259.00 264.00
TABLE 1:
1. SBR 1500 – used as base polymer from KUMHO PETROCHEMICALS ML (1+4) @ 100°C is 46-58
2. Whole Tyre Reclaim (WTR) – used from BALAJI RUBBER.
3. N660 – black used as a reinforcing filler from BIRLA CARBON.
4. Cloisite 20- an organically modified nanoclay used as an additive for rubber to improve various physical properties, such as reinforcement and barrier. CLOISITE 20 is bis (hydrogenated tallow alkyl) dimethyl, salt with bentonite. It is off-white in color and has got a typical dry particle size less than 10 micrometers and a d-spacing of 3.16 nanometers It is procured from BYK-Chemie GmBH, Germany
5. Precipitated Calcium carbonate – used as reinforcing filler from ARANTHANGI CHEMICALS PVT LTD.
6. Low Poly Cyclic Aromatic oil (PCA oil) used as processing aid from INDIAN OIL CORPORATION LTD.
7. Zinc Oxide – used as cure activator from PONDY OXIDES & CHEMICALS.
8. Stearic Acid – used as processing aid for viscosity reduction and as an activator for vulcanization from GODREJ INDUSTRIES.
9. Capolyte Resin (CP90) used as a tackifier resin from MANGALAM ORGANICS.
10. Insoluble Sulphur as a curative from ORIENTAL CARBON & CHEMICLAS LTD.
11. N-Cyclohexyl Benzothiazole Sulfenamide (CBS) – used as an accelerator for faster curing from NOCIL LTD.
12. Anti degradants - Trimethyl dihydro quinoline (TMQ), Para phenylene diamine (6PPD) from LANXESS.
TEST CHARECTERIZATIONS
The developed samples were cured and typically characterized for stiffness, mechanical and gas permeability properties.
Motorcycle tire bead insulated with the developed nanocomposite has superior stiffness, rigidity, and gas impermeability.
TABLE 2:
S.No Properties Control Trial 1 Trial 2
1 Tensile Strength (MPa) 13.72 14.98 13.81
2 Modulus 10% (MPa) 1.9 2.43 2.56
3 Button Stiffness(kgf/mm) 202.25 239.25 220.98
4 OTR (cc/m².day) 33.641 31.32 24.294
INDEX
S.No Properties Control Trial 1 Trial 2
1 Tensile Strength 100 109 101
2 Modulus 10% 100 128 135
3 Button Stiffness 100 118 109
4 OTR 100 93 72

NOTE:
• The results are compared with each other by index value.
• In case of tensile strength, modulus and stiffness, higher index value indicates better property for trial as compared to control.
• In case of gas permeability, lower value refers to better gas impermeability.

Table 2 shows the comparison results of Control Compound and organically modified Nanoclay-filled compound with dosages 5 phr (Trial 1) and 10 phr (Trial 2) on various properties.

1. The tensile strength of the control bead compound is 13.72 MPa and increases on adding organically modified nanoclay. Tensile strength increases to 14.98 MPa with the addition of 5 phr of organically modified nanoclay and 13.81 MPa with 10 phr of organically modified nanoclay addition, thus, showing an improvement of 9% and 1 % respectively.

2. 10% modulus for the control bead compound is 1.9 MPa and increases to 2.43 MPa with 5 phr of organically modified nanoclay and 2.56 MPa with 10 phr of organically modified nanoclay in the composite. Thus, the improvement seen is 28% and 35% respectively.

3. Button Stiffness for the control bead compound is 202.25 kgf/mm and increases to 239.25 kgf/mm with 5 phr of organically modified nanoclay and 220.98 kgf/mm with 10 phr of organically modified nanoclay in the composite and hence, showing an improvement of 18% and 9% respectively.

4. The gas permeability rate should be low in bead application. The control bead compound has an OTR of 33.641 cc/m3.day. It reduces to 31.32 cc/ m3.day with 5 phr of organically modified nanoclay and 24.294 cc/ m3.day with 10 phr of organically modified nanoclay addition and provides an improvement of 7% and 28% respectively.

STANDARD TESTS AND PROCEDURES
1. The tensile strength of a nanocomposite is the measure of maximum tensile stress applied on a material to rupture. The tensile strength is measured as per ASTM D 412 with the help of universal testing machine (model: 5966, Instron, MA, USA)
2. Modulus of an elastomeric material is the stress needed to strain a material. The modulus is measured as per ASTM D 412 in universal testing machine (model: 5966, Instron, MA, USA).
3. Button stiffness provides the compression/deflection characteristics of rubber compound. Button stiffness is measured as per standard ASTM D 575 in universal testing machine (model: 5966, Instron, MA, USA). .
4. The oxygen permeability in a sample is measured as per standard ASTM F 1927-14. Oxygen transmissibility rate (OTR) is defined as the quantity of oxygen gas that passes through a unit area of a surface per unit time at a given temperature and relative humidity. The permeability rate should be low for bead application. ,CLAIMS:WE CLAIM:
1. A tyre bead comprising,
bead wire; and
bead insulation comprising a rubber nanocomposite and one or more fillers comprising a reinforcing filler and organically modified nanofillers or nanoclay in the ratio of 50 – 100 phr: 0.5-15 phr.

2. A rubber nanocomposite for bead insulation, comprising of:
rubber nanocomposite comprising one or more elastomers – 100 phr;
reinforcing fillers comprising carbon black – 50 – 100 phr and precipitated calcium carbonate – 5 – 30 phr;
organically modified nanofiller – 0.5 – 0.15 phr;
processing aid – 1 – 30 phr;
cure activator – 1- 10 phr;
tackifier resin – 1 – 15 phr;
curative – 1- 15 phr;
accelerator – 1- 5 phr; and
anti-degradant – 1- 6 phr,
wherein the filler comprises of carbon black as reinforcing filler and is partially replaced by organoclay or nanoclay of particle size 0.1 to 10 micrometres and d-spacing of 2.5 to 3.5 nanometres.
3. The rubber nanocomposite for bead insulation as claimed in claim 2, wherein said organically modified nanoclay is Bis(hydrogenated tallow alkyl) dimethyl, salt with bentonite.

4. The rubber nanocomposite for bead insulation as claimed in claim 2, wherein said elastomers comprises of styrene butadiene rubber, reclaim rubber, natural rubber and combinations thereof.

5. The rubber nanocomposite for bead insulation as claimed in claim 2, wherein said elastomers comprises of emulsion of styrene butadiene copolymer (E-SBR) and reclaim rubber (WTR) in a weight ratio of 97 : 6.

6. The rubber nanocomposite for bead insulation as claimed in claim 2, wherein said reinforcing filler comprises of carbon black N550, carbon black N660 and combinations thereof.

7. The rubber nanocomposite for bead insulation as claimed in claim 2, wherein the cure activator is Zinc oxide.

8. The rubber nanocomposite for bead insulation as claimed in claim 2, wherein the tackifier resin comprises of capolyte, hydrocarbon and combinations thereof.

9. The rubber nanocomposite for bead insulation as claimed in claim 2, wherein the curative is selected from one of soluble sulphur and insoluble sulphur.

10. The rubber nanocomposite for bead insulation as claimed in claim 2, wherein the processing aid comprises of stearic acid, oils, homogenising aids and combinations thereof.

11. The rubber nanocomposite for bead insulation as claimed in claim 2, wherein the accelerator comprises of N-cyclohexyl benzothiazole sulfenamide (CBS), N-tert-butyl-2-benzothiazyl sulfenamide (TBBS) and combinations thereof.

12.The rubber nanocomposite for bead insulation as claimed in claim 2, wherein the anti-degradant comprises of trimethyl dihydro quinoline (TMQ), para phenylene diamine (PPD), 2,2,4-trimethyl-1,2-dihydroquinoline (TQ) and combinations thereof.

13. A process of preparation of rubber nanocomposite for bead insulation, comprising of steps:
conditioning of a nanofiller by subjecting it to an initial pre-drying at a temperature range between 60°C and 80°C in heat aging oven for 12-48 hours to remove all the entrapped moisture;
preparation of master batch by,
initial mixing the ingredients in Banbury mixer;
initial masticating the rubber for 20-60 seconds;
loading of chemicals comprising cure activators, anti degradants, and tackifier resin;
adding of organically modified nanoclay followed by the addition of reinforcing fillers;
mixing for 180 – 250 seconds , sweeping off the chemicals from the chamber walls; again mixing for 80 – 160 seconds; and
dumping of mixed rubber nanocomposite to get the master batch mix, wherein the rotor speed is maintained constantly in the range 50-70 rpm, temperature of mixing is maintained around 60-80°C and the fill factor of the chamber is 0.70- 0.90, wherein the total mixing time of the master batch compound is 4-8 minutes, and the dump temperature of the rubber nanocomposite is 145-165°C, and the master batch is subjected to further mixing process to yield a final batch.

14. The process of preparation of rubber nanocomposite for bead insulation as claimed in claim 13, wherein the final batch mixing process comprises of steps:
Initial warming of master batch for 15-45 seconds; and
adding curative and accelerator to the master batch,
wherein the starting temperature range of mixing is between 30°C and 50°C, the rotor speed is maintained at 30 - 60 rpm and the dump temperature range varies between 105°C-120°C.

15. The rubber nanocomposite for bead insulation as claimed in claim 1, wherein the tensile strength of the bead insulation is in the range of 13.81 to 14.98 MPa at a concentration range of 5 to 10 phr of nanoclay.

16. The rubber nanocomposite for bead insulation as claimed in claim 1, wherein the 10% modulus of the bead insulation is in the range of 2.43 to 2.56 MPa at a concentration range of 5 to 10 phr of nanoclay.

17. The rubber nanocomposite for bead insulation as claimed in claim 1, wherein the button stiffness of the bead insulation is in the range of 220.98 to 239.25 kgf/mm at a concentration range of 5 to 10 phr of nanoclay.

18. The rubber nanocomposite for bead insulation as claimed in claim 1, wherein the gas permeability rate of the bead insulation is in the range of 24.294 to 31.32 cc/m2.day at a concentration range of 5 to 10 phr of nanoclay.