FORM 2
THE PATENTS ACT, 1970
(Act 39 of 1970)
AND
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION (See section 10; rule 13)
TITLE OF THE INVENTION INNER LINER SYSTM FOR PNEUMATIC TUBELESS TYRES
APPLICANT
CEAT LIMITED
of RPG HOUSE, 463, Dr. Annie Besant Road,
Worli, Mumbai 400 030, India;
Nationality: India
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed.

FIELD OF THE INVENTION
The present invention relates to inner liner system for pneumatic tubeless tyre in which the inner liner system comprises single inner liner which has both air- impermeability property as well as compatibility with inner ply.
BACKGROUND OF THE INVENTION
Conventionally, inner liner system for use in pneumatic tires comprises two or more layers at least one of which is made out of butyl or halogenated butyl rubber to inhibit theloss of air or oxygen therethrough, such as to maintain pressure over extended periods of time. Often times, however, touse these butyl rubber-based materials, an additional rubberlayer, e.g., a transition inner liner layer, with low hysteresis loss is sandwiched between the barrier layer, e.g., an innerliner, and the inner ply of the tyre. This additional transition inner liner layer undesirably increases the weight of tyre and costs of production. Traditionally, inner liner and transition inner liner are calendered separately and assembled together. The compound is introduced through cold feed extruders. Two separate extrudates are taken through two different conveyors. The upper conveyor is for inner liner and lower one for transition inner liner. The extrudate is taken through the nip of the calendar and comes out as a single output. It is allowed to wind on it. The extrudate is then air cooled using eight cooling drums. The cutting knives are adjusted for the specified width and the cut liner is introduced in the take-off conveyor. The liner is then passed over the guide roller and the space of the guide roller is adjusted for proper centering. The moving base assembly and camera do the appropriate centering of the liner. Prior art US 6,293,327 attempts to reduce the weight of the tyre. It describes a durable, light weight pneumatic tubeless tyre without an inner liner in which the topping rubber layer has adhesion properties to the embedded caserods and other members containing diene rubber. However, disadvantages associated therewith include issues such as gauge variation in the processing leads to cord visibility issue after curing of the tyre which is not allowed. Further, the formulation taught by this prior art is costly and the process is tedious especially during actual industry application.
In view of the shortcomings of the state of the art, there exists a need for light weight pneumatic tyres in which the transition inner liner layer is obviated.

OBJECTS OF THE INVENTION
An object of the present invention is to provide a light weight durable pneumatic tyre in which multiple inner liner layers are eliminated.
Another object of the present invention is to provide for a light weight durable pneumatic tyre in which the single layer inner liner is air-impermeable and at the same time compatible with inner ply of the tyre.
Yet another object of the present invention is to reduce weight of the tyre and overall costs of production.
SUMMARY OF INVENTION
The present invention relates to an inner liner system for pneumatic tubeless tyre comprising a single inner liner layer, said layer being air-impermeable and compatible with inner ply eliminating the need for additional layers in inner liner systems.
DETAILED DESCRIPTION OF THE INVENTION
For the purposes of the following detailed description, it is to be understood that the invention may assume various alternative variations and step sequences, except where expressly specified to the contrary. Moreover, other than in any operating examples, or where otherwise indicated, all numbers expressing, for example, quantities of ingredients used in the specification are to be understood as being modified in all instances by the term “about” in which “about” is defined as ± 10% of the nominal value. It is noted that, unless otherwise stated, all percentages given in this specification and appended claims refer to percentages by weight of the total composition.
Thus, before describing the present invention in detail, it is to be understood that this invention is not limited to particularly exemplified process parameters that may of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments of the invention only, and is not intended to limit the scope of the invention in any manner.

The use of examples anywhere in this specification including examples of any terms discussed herein is illustrative only, and in no way limits the scope of the invention or of any exemplified term. Likewise, the invention is not limited to various embodiments given in this specification.
Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by a person skilled in the art to which this invention pertains. In the case of conflict, the present document, including definitions will control.
It must be noted that, as used in this specification and the appended claims, the singular forms “a,” “an” and “the” include plural referents unless the content clearly dictates otherwise. The terms “preferred” and “preferably” refer to embodiments of the invention that may afford certain benefits, under certain circumstances. However, other embodiments may also be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, and is not intended to exclude other embodiments from the scope of the invention. As used herein, the terms “comprising”, “including”, “having”, “containing”,“involving” and the like are to be understood to be open-ended, i.e., to mean including but not limited to.
In one embodiment, the present invention describes an inner liner system for pneumatic tubeless tire comprising a single inner liner layer which is compatible with inner ply of the tyre as well as has air-impermeability properties. This novel inner liner system of the present invention eliminates the need for additional layers conventionally known in the art as transition inner liner.
In one aspect of present invention, there is provided the inner liner system of the present invention. The inner liner system comprises a single inner liner composed at least of ternary blend of natural rubber in about 3-11%w/w of the composition, styrene butadiene rubberin about 26-36%w/w of the composition and butyl reclaimin about 15-25%w/w of the composition as primary components. In another embodiment, the ternary blend includes poly synthetic isoprene rubber with styrene butadiene rubber and butyl reclaim

rubber. In another embodiment, the preferred ratio is about 15%:50%:35% of the total rubber used as primary components.
The secondary components comprised in the inner liner includefillers and other adjuncts. Fillers are selected from at least one of nano-sized exfoliated kaolin clay in about 14-24%w/w of the composition, carbon black in about 10-20%w/w of the composition, mica and calcium carbonate. Adjuncts include activators for crosslinking of rubber selected from zinc oxide, stearic acid, crosslinking agents, accelerators, antioxidants, aromatic hydrocarbon resins and oils. Preferably, the filler comprises nano-sized exfoliated kaolin clay and carbon black in a ratio of 1:1. Nano-size of the kaolin clay increases the air-impermeability resulting in a more effective liner system. Exfoliation of kaolin is done by any known physical or chemical process. In case of chemical exfoliation, additional components such as a cationic mediator known in the art may be added to preparation of single inner liner.
Crosslinking agents such as sulphur, accelerators include selecting at least one of MBTS
(Benzothiazyl disulfide), TBBS (N-tert-butyl-2-benzothiazyl Sulfenamide), CBS (N-
Cyclohexyl-2-benzothiazole Sulfenamide), activators include selecting at least one of
zinc oxide, stearic acid, anti-oxidants include selecting at least one of 6PPD (N-(1,3-
dimethylbutyl)-N'-phenyl-P-phenylenediamine), IPPD (N-isopropyl-N'-phenyl-P-
phenylenediamine), TMQ ( 2,2,4-Trimethyl-1,2-Dihydroquinoline polymer).
In another aspect of present invention, the inner liner may be further lined with an air sealant composition to increase air impermeability. Preferably, the air sealant composition patented in the Applicant’s earlier patent application no. 11/MUM/2015, the contents of which are incorporated herein by reference, may be used. The said air sealant composition comprises rubber component, tackifier, naphthenic oil, fillers and is devoid of fibrous material and crosslinking agent.
The following examples are provided to better illustrate the claimed invention and are not to be interpreted in any way as limiting the scope of the invention. All specific materials, and methods described below, fall within the scope of the invention. These specific compositions, materials, and methods are not intended to limit the invention, but

merely to illustrate specific embodiments falling within the scope of the invention. One skilled in the art may develop equivalent materials, and methods without the exercise of inventive capacity and without departing from the scope of the invention. It is the intention of the inventors that such variations are included within the scope of the invention.
EXAMPLE 1:

Ingredient Range (%w/w)
Natural rubber 3-11
Styrene butadiene rubber 26-36
Butyl reclaim 15-25
Nanoclay 14-24
Carbon black 10-20
Zinc oxide 1-2
Stearic acid 0.3-0.8
Antioxidant 6PPD 0.5-1.5
Antioxidant TQ 0.5-1.5
Aromatic hydrocarbon resin 1.5-3.5
Naphthenic oil 1-3
Sulfur 0.7-1.5
MBTS (thiazole) 0.07-0.15
TBBS (sulfinamide) 0.1-0.22
The method comprises the steps of mixing all components except crosslinking agents and accelerators in Banbury for 150-170 seconds at 155-165°C. Mixing resultant components with crosslinking agents and accelerators for 120-140 seconds at 100-110°C followed by sheeting out in 6mm in tween screw sheeter.
The energy consumed in the first mixing procedure is 18 Kw/h – 20Kw/h and during second and final mixing procedure is 7kw/h – 9Kw/h. The viscosity obtained is 70-80 Mooney units for final batches.

The above example was subjected to the following tests -
a. H-adhesion test to confirm compatibility of inner liner with inner ply compound
– Ply is the fabric coated with rubber compound which is running throughout the
body of the tyre, is a inner component of the tyre. It does not interface with road
surface. The test is carried out as per standardised procedure laid down in ASTM
D4776. The standard for H-adhesion index for inner liner is 80-100. For present
invention, the index for inner liner obtained is 90.
b. Gauge consistency of inner liner – Green gauge of the component is designed as
per the cured tyre specification and consistency in the gauge throughout the tyre
is a critical parameter. Values of green gauges are different for different
applications like passenger car tyre, motorcycle tyre. Air leakage is dependent on
the gauge consistency of inner liner of tyre.
c. Shrinkage % - The test is carried out as per an in-house test method and the
standard is that shrinkage of the inner liner should not be more than 20%. The
result is arrived based on the compound processed in the factory which is meeting
the specification in the manufacturing process. Mill shrinkage test method of
compound is carried out as follows –
a. Set roll temperature to 70°C
b. Set roll gap to 2mm
c. Compound required is 1-1.5kg
d. Milling time is 3 mins
e. During milling make cut in compound and re-mill (for dispersion)
f. Stop milling and cut a sample of 150X50 mm lengths. No. of sample 03.
g. Put the sample on free surface (talc/dusting) for 24 hours
h. Cover the surface of the box checking the length
i. Change in length of sample before and after is the shrinkage %.
The results are as follows –

Sr. No. Sample Shrinkage %
1. Inner Liner known in prior art 18%

2. Transition Inner Liner known in prior art 10%
3. Inner liner of present invention 19%
d. Air retention test – This test is done by moulding tyre and checking the air retention test against the standard running inner liner following ASTM F1112. Index of air loss per month – tyre with inner liner and transition liner is 100 and tyre with single liner is 109 (higher the index, the better)
Advantageously, the tubeless inner liner composition with no virgin butyl rubber. A general purpose based composition is used which is low cost and easy to prepare compared to expensive butyl rubber. Another advantage is that the transition liner is eliminated completely with single non butyl inner liner. Presence of natural rubber in inner liner enhances green strength. It is more compatible with inner ply compound because it is made of natural and synthetic rubbers but not of pure halo butyl rubber. Nano-clay improves air impermeability which is a key function of inner liner. Combination of styrene butyl rubber and natural rubber facilitates co-curing with adjacent component, and hence use of transition liner can be eliminated. Inner liner and transition inner liner are made as a single component instead of two components. One process step is lesser compared to the process used in tyre industry. Low cost and no special care required.
While specific embodiments of the invention have been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of the invention which is to be given the full breadth of the appended claims and any and all equivalents thereof.

We claim:
1. An inner liner system for pneumatic tubeless tyre comprisinga single inner liner layer, said single inner liner layer being air-impermeable and compatible with inner ply of said tyre eliminating the need for additional layers in inner liner systems.
2. The inner liner system for pneumatic tubeless tyre wherein the single inner liner layer comprises combination of natural rubber in about 3-11%w/w of the composition, styrene butadiene rubber in about 26-36%w/w of the composition and butyl reclaim in about 15-25%w/w of the composition as primary componentswith fillers and adjuncts as secondary components.
3. The inner liner system for pneumatic tubeless tyre as claimed in any of the preceding claims wherein the preferred ratio of primary components is 15%: 50%: 35% respectively.
4. The inner liner system for pneumatic tubeless tyre as claimed in any of the preceding claims wherein the filler is selected from at least one of nano-sized exfoliated kaolin clay, carbon black, mica and calcium carbonate.
5. The inner liner system for pneumatic tubeless tyre as claimed in claim 4 wherein nano-sized exfoliated kaolin clay is about 14-24%w/w and carbon black is about 10-20%w/w.
6. The inner liner system for pneumatic tubeless tyre as claimed in claim 4wherein the filler comprises nano-sized exfoliated kaolin clay and carbon black in a ratio of 1:1.
7. The inner liner system for pneumatic tubeless tyre as claimed in any of the preceding claims wherein the adjuncts include activators for crosslinking of rubber selected from zinc oxide, stearic acid, crosslinking agents, accelerators, antioxidants, aromatic hydrocarbon resins and oils.

8. The inner liner system for pneumatic tubeless tyre as claimed in any of the preceding claims wherein the single inner liner layer is further layered with a tire sealing agent comprised of rubber component, a tackifier, naphthenic oil and filler, said sealing agent devoid of fibrous material and crosslinking agent.
9. The inner liner system for pneumatic tubeless tyre wherein the single inner liner layer has H-adhesion index of at least 90 and air retention index of 109.
10. A method of preparing a single inner liner layer for inner liner system of pneumatic tubeless tyre comprising the steps of –
a. Mixing primary and secondary components except crosslinking agents and
accelerators in Banbury for 150-170 seconds at 155-165°C;
b. Mixing components of step (a) with crosslinking agents and accelerators for
120-140 seconds at 100-110°C;
c. Sheeting out in 6mm in tween screw shooter.
d. Layering the resultant inner liner layer with a sealing agent.