Description:FIELD OF INVENTION
The present invention relates to the field of pneumatic tyre. The present invention in particular relates to a precure application method of an off-highway tyre (OHT) building process incorporating a self sealing layer inside a tyre, which enhances safety, puncture resistance, durability, and supporting for sustainable tyre designs.
BACKGROUND OF THE INVENTION
Conventional pneumatic tyres used in off-highway applications (OHT) are frequently exposed to sharp stones, metal debris, and agricultural stubble, resulting in punctures and air loss. Existing solutions, such as sealant-injected tyres, add complexity, non-uniformity, and handling difficulties. Such sealants may migrate, leak, or cause inner-liner damage.
Reference made to the following:
Patent No. US4037635 relates to a puncture proof vehicle tire comprising two symmetrical halves mounted on a divided felly, wherein the tread and the foot of each tire half are connected by a resilient, reinforcing connecting portion which comprises a plurality of supporting members having been formed by axial cut-outs. It is preferred to arrange the axial cut-outs in such a way, that the supporting members of the connecting portion are segment-like and alternately arranged in opposite directions and thus in successive segments are orientated alternately towards the felly edge and the felly center but it fails to disclose about the self-sealing process technology of a tyre.
Publication No. US2010200131 relates to a non-pneumatic tire having a support structure body supporting a load from a vehicle, the support structure body (SS) comprises an inner annular portion an intermediate annular portion provided concentrically in an outer side of the inner annular portion, an outer annular portion provided concentrically in an outer side of the intermediate annular portion, a plurality of inner coupling portions coupling the inner annular portion and the intermediate annular portion and being independent in a circumferential direction, and a plurality of outer coupling portions coupling the outer annular portion and the intermediate annular portion and being independent in a circumferential direction. The referred patent discusses about the inner annular portion of a non pneumatic tyre which is provided with a support structure body having an inner ring, an intermediate ring (constructed as a reinforcing structure by a plain weave fabric of a glass fiber), an outer ring, inner spokes (standing erect in a radial direction) and outer spokes (standing erect in a radial direction) coupling the respective rings, three layers of reinforcing layers provided in an outer periphery thereof, and a tread rubber but it fails to disclose about self sealing technology of a tyre.
Patent No. US8474499 relates to a tire and methods of manufacture thereof comprising a tire body and a metal reinforcing strip comprising at least one metal alloy foil layer to provide puncture resistance, wherein the at least one metal alloy foil layer comprises a spin odal glass matrix micro constituent structure. The referred patent discussed the use of metal reinforcing layer to provide puncture resistance but it fails to disclose about the self-sealing technology of a tyre
Publication No. EP4253097 relates to the tires sector, and it refers to, more specifically, a system of shield levels for tire protection that prevents sharp objects from puncturing the inner tube or in tubeless tires that prevent sharp objects from emptying the air from the tire, which can be applied to practically every kind of tire. The referred patent discussed about the shield, characterized by being a part positioned juxtaposed to and internally to the tire's rubber, shaped like the tire's inner surface, 0.3mm to 500mm thick with Shore D hardness between 40D and 100D; and with Shore hardness between 80A and 40D with 2mm to 500mm thick and produced in thermoplastic or thermosetting polymer but it fails to disclose about the tyre self-sealing process technology.
Publication No. GB2284183 relates to a puncture-proof tyre assembly includes a first annular portion engageable with a wheel rim. A second annular portion engages the first annular portion so that there is at least one non-pressurizable chamber with means for absorbing impacts. In Fig. 2 the impact absorbing means includes a helically wound flat spring ring forming the second annular portion. The referred patent discussed the puncture proof tyre assembly for a bicycle tyre wherein its second annular portion containing a plurality of sealed chambers there between, but it fails to disclose about the application of self-sealing layer throughout the tyre.
Publication No. IN7556/DELNP/2015 relates to a tyre of which the internal surface is covered with a sealed layer which is itself covered with a layer of self-sealing product comprising a radial carcass reinforcement consisting of reinforcing elements having an elongation at break AR and a breaking force FRC laid at a laying pitch PC and coated with a rubber composition dimensioned so as to satisfy the inequality: in which FRC is expressed in Newtons RS is the radial distance between the rotational axis of the tyre and the radially outermost point of the carcass reinforcement RE is the radial distance between the rotational axis and the axial position where the tyre reaches the maximum axial width of same and RT is the radial distance between the rotational axis and the radially innermost point of the bead core the laying pitch PC and radial distances RS RE and RT being expressed in metres; each sidewall of the tyre further comprising an additional reinforcement consisting of wire reinforcing elements having an elongation at break ARS and a breaking force FRS laid at a laying pitch PS and coated with a rubber composition in which each of the two additional reinforcements is dimensioned such that and ARC=ARS breaking forces FRS and FRC and elongations at break ARC and ARS being determined on the reinforcing elements after extraction of the cured tyre. The referred patent discusses the application of reinforcing layer after curing of the tyre i.e., application of a sealant layer by post cure method whereas present invention discusses about the precure application method of self-sealing layer in off highway tyre.
Publication No. IN7565/DELNP/2015 relates to a tyre of which the internal surface is covered with a sealed layer which is itself covered with a layer of self-sealing product comprising a radial carcass reinforcement consisting of reinforcing elements having an elongation at break ARand a breaking force FRc laid at a laying pitch PC and coated with a rubber composition dimensioned so as to satisfy the inequality: (Formula I) in which FRc is expressed in Newtons Rs is the radial distance between the rotational axis of the tyre and the radially outermost point of the carcass reinforcement RE is the radial distance between the rotational axis and the axial position where the tyre reaches the maximum axial width of same and Rt is the radial distance between the rotational axis and the radially innermost point of the bead core laying pitch Pc and radial distances Rd RE and Rt being expressed in metres; each sidewall of the tyre further comprising an additional reinforcement consisting of wire reinforcing elements having an elongation at break ARS and a breaking force FRs laid at a laying pitch Ps and coated with a rubber composition in which each of the two additional reinforcements is dimensioned such that (Formula II) ARC= ARS breaking forces FRs and FRc and elongations at break ARc andARs being determined on the reinforcing elements before incorporation into the tyre. The referred patent discusses the application of reinforcing layer after curing of the tyre i.e., application of a sealant layer by post cure method whereas present invention discusses about the precure application method of self-sealing layer in off highway tyre.
Patent No. US9662939 relates to a non-pneumatic tire for supporting a load by working in tension. The tire can comprise a generally annular inner ring, a generally annular outer ring, and a web having a plurality of web elements. The tire can further comprise a layer or layers fabric material acting as a bonding agent to bond tire components together. The referred patent discussed about the shield, characterized by being a part positioned juxtaposed to and internally to the tire's rubber, shaped like the tire's inner surface, 0.3mm to 500mm thick with Shore D hardness between 40D and 100D; and with Shore hardness between 80A and 40D with 2mm to 500mm thick and produced in thermoplastic or thermosetting polymer but it fails to disclose about the tyre self-sealing process technology.
Publication No. JP2005126654 relates to a material injectable into a tire tube as a substitute of air to make the tire punctureless and excellent in vibration-absorbing characteristics. By injecting an oil-extended soft elastomer consisting of a styrene or olefin crystalline block as a hard segment with a block of butene, ethylene-butene, ethylene-propylene or isoprene as a soft segment into the tire tube to replace air, the tire is made as punctureless, while maintaining an equivalent vibration-absorbing characteristics to the air. The referred patent discussed the injection of oil-extended soft elastomer consisting of a styrene or olefin crystalline block as a hard segment into the tyre tube to replace air, but it fails to disclose about the tyre self-sealing process technology.
Patent No. US3982577 relates to a tube guard for protecting inner tubes of relatively thin tires. The tube guard is comprised of a unitary annular guard member molded from a solid flexible synthetic polymeric material having a high Shore hardness. The referred patent discussed about the tube guard which is made from solid flexible synthetic polymeric material having a high Shore hardness, but it fails to disclose about the tyre self-sealing process technology.
Patent No. US5679184 relates to a device for preventing a pinch puncture of an inner tube of a pneumatic tire, which is disposed within a tire casing fitted over a wheel rim, includes a resiliently deformable ring disposed between the inner tube and the rim. The intermediate section of the ring includes a neck having a reduced width relative to the base section. The referred patent discussed the resiliently deformable ring which includes a flat base section positioned between the inner tube and rim which prevents a pinch puncture of an inner tube of a pneumatic tyre, but it fails to disclose about the tyre self-sealing process technology.
Publication No. US2019344626 relates to a tire structure capable of being combined with a rim, and the tire structure includes an air tube, a core provided on the air tube, and a tire outer layer provided on the core, and the core includes a body part positioned above a transverse diameter of the air tube and a wing part positioned under the transverse diameter of the air tube, and a lower end of the wing part is placed under an upper surface of the rim. The referred patent discussed about a tyre structure includes an air tube and a core is provided on the air tube which helps to suppress damage and puncture in a tire caused by an external stimulus such as a sharp object, e.g., a nail, on the tread during a ride.
Publication No. GB2024118 relates to a puncture resistant pneumatic tyre includes a casing 70 and an inner tube 75 or a base ring of foam rubber (Figure 3 not shown), where the side walls of the casing flex under load, in combination with an elastomeric shield 72 (or 55). The outer surface of the elastomeric shield is contoured to mate with the inside surface of the casing and the inner surface of the shield may be shaped as at 77, 772 or 773. The referred patent discussed about the puncture resistant pneumatic tyre comprising a casing having flexible side walls and a concave surface thereon with tread on a peripheral outer edge thereof, a compressible elastomeric shield of high density foamed material in the form of a ring concave in cross-section having an outer peripheral surface mating with the concave inner surface of the casing, the outer peripheral surface of the elastomeric shield co-operating and converging with the inner surface of the casing to define a tapered flap along each side wall of the casing, and a pneumatic tube disposed within the annular space defined by the concave elastomeric shield but it fails to disclose about the precure application method of self-sealing layer in off highway tyre. Moreover, the present invention does not contain a compressible elastomeric shield of high density foamed material.
Publication No. WO2019133009 relates to pneumatic tires having improved rolling resistance performance. Said tires include a cap ply extending at least partially across a full width of at least one of the belt plies, the cap ply being characterized as having a rupture force greater than 210 N per 15 mm of the cap ply width.. The referred patent discussed a tyre with improved rolling resistance, but it fails to disclose about the self-sealing process technology.
Patent No. US8959990 relates to an arrangement of a tire pressure sensor unit on the inner wall of the tread of a vehicle tire in a retaining device for the sensor unit is provided. The referred patent discussed a tyre sensor unit on the inner wall of a tyre which contains a self-sealing compound and the system prevents a short-term loss of pressure caused by the foreign object whereas present invention discusses about the precure application method of self-sealing layer in an off highway tyre.
Patent No. US5785779 relates to a protective tire liner is positioned between the bicycle inner tube and the bicycle outer tire of a bicycle wheel. The tire liner includes a puncture-resistant flexible strip to protect the inner tube from puncture damage, and at least one covering layer on the puncture-resistant flexible strip to cover at least the side edges thereof. The referred patent discussed the puncture-resistant flexible strip positioned between the innertube and outer tyre of a bicycle tyre to prevent tube from puncture damage whereas present invention discussed about the self-sealing technology of a tyre.
Patent No. US8573271 relates to tubeless tire in the form of a torus open radially inwards with an outer wall and an inner wall, characterized in that at least part of the inner wall is covered with a self-sealing layer comprising a thermoplastic styrene (TPS) elastomer having a Shore 0 hardness of less than 35. The referred patent discussed the self-sealing layer’s rubber composition containing thermoplastic styrene, but it fails to disclose the precured application method of an off highway tyre.
Publication No. US2016303909 relates to a safety tire in combination with a rim includes an outer tube; a reinforcing layer secured to the outer tube; and a plurality of partitions for dividing a space formed by the reinforcing layer, the outer tube, and the rim into a plurality of compartments. The referred patent discussed a safety tire in combination with a rim comprising an outer tube, a reinforcing layer secured to the outer tube; and a plurality of partitions for dividing a space formed by the reinforcing layer, the outer tube, and the rim into a plurality of compartments to prevent tyre blow out at high speed but it fails to disclose the self-sealing technology of a tyre.
Publication No. US2006151082 relates to a self-sealing puncture-proof pneumatic tubeless tire comprising a layer of soft non-cured gum rubber compound fixedly attached to the inner surface of the tire and a layer of soft textured nylon ply reinforced rubber secured by the adhesive effect of the non-cured gum rubber compound and vulcanized at the wire bead section of the tire, thereby enclosing the soft non-cured gum rubber compound. The referred patent discussed a self-sealing puncture proof pneumatic tubeless tyre with the non-cured gum rubber compound, but it fails to disclose about the precured application methodology of an off highway tyre.
Publication No. WO2007035076 relates to a method of producing solid flexible inner tubes for tyres, which are made from polyurethane elastomer material and which are characterised in that they can recover the original shape thereof, with the self-sealing of punctures, and to inner tubes thus obtained. The referred patent discussed the inner tube of tyres made from polyurethane elastomer material but it fails to self-sealing technology of a tyre.
Publication No. EP3450208 relates to a four-proofing safety tire including a conductive tread rubber layer, a supporting rubber layer, a tire explosion-proof rubber layer and a memory chip, wherein the conductive tread rubber layer can be formed by embedding, in the tread, a belt of narrow conductive rubber penetrated all the way to the inner cap ply or can be formed by adding carbon nanotubes or graphene conductive metamaterial to the tread formulation; the supporting rubber layer is a layer of rubber affixed on the inner wall of the sidewall when the tire is molded, which has a cross section with the shape of half slice of a willow leaf. The referred patent discussed the four proof safety tyre containing an explosion-proof layer having strong puncture-resistant property to effectively avoid the flat tire caused by puncture but it fails to disclose about a self-sealing layer application methodology of an off highway tyre.
Publication No. FR2879504 relates to the anti-puncture system consists of a protective liner that covers the inner surface of a vehicle tyre and is held in place by air pressure. The liner is sufficiently supple and strong to deform when the tyre is penetrated by a sharp object such as a nail, forming a barrier to perforation, and covers the whole of the tyre's inner surface, including the areas of the tread and side walls as far as the wheel rim. The referred patent discussed about a tyre consists of a sheet material, disposed inside the tire so as to be applied against its innerface to form a barrier to perforation, this envelope being determined to have a flexibility and a sufficient resistance to deform without being perforated in case of penetration of a sharp element inside the tire, but it fails to disclose a precured application method of an off highway tyre.
Publication No. GB190705531 relates to a band, arranged between the cover and the air-tube to prevent puncture, comprises cane strips C, Figs. 4 and 5, of semicircular or rounded cross - section alternating with overlapping flat or rounded strips D linked together by thread f, the strips being tapered at the ends and, in some cases, bent to conform with the shape of the tyre. The inner strips D may be shorter than the outer strips C, and both sets of strips may be arranged transversely or diagonally to the tread of the tyre. The referred patent disclosed about a band, arranged between the cover and the air-tube to prevent puncture, but it fails to disclose about a self-sealing technology of a tyre.
Publication No. GB190619905 relates to a studded tread band 3 of balata belting, stitched or other canvas belting, or chrome leather, with a packing 7, preferably of Gandy belting, to conform with the shape of the tread of the tyre, is cemented to a water-proofed sail-canvas backing 6, cemented to the tyre and provided with side straps 9 passing round the beads of the tyre. The straps 9 are folded over near the tread band, leaving wide tabs 10 at the ends, the spaces between which may be filled in with canvas to provide an even bearing against the rim of the wheel. The referred patent discussed a puncture proof band, but it fails to discuss about a self-sealing technology of a tyre.
Publication No. GB190504184 relates to a pneumatic tyre for motor or other road vehicles to the rim, studs f on metal plates g project through eyeleted holes b* in the stiffened edges b of the outer cover and through the edges c of the metal rim d, the plates g being held down by nuts k on the threaded stems h. The studs are longer on one side of the plates than on the other. In modifications, the studs may be on the edges of the outer cover or on the rim, instead of on the holding-plates g. The referred patent discussed non slipping puncture proof band, but it fails to disclose about self-sealing technology of a tyre.
Publication No. GB190422026 relates to a protective non-slipping cover for pneumatic tyres comprises cross-pieces of rouud wire or bands of metal or other suitable material b threaded or looped on to flexible wires or bands a. When the tyre is to be completely covered, as shown in Fig. 3, each of the crosspieces is preferably made in three pieces d, the ends of which are halved and loosely riveted together. The referred patent discussed non slipping puncture proof cover of a pneumatic tyre, but it fails to disclose about self-sealing technology of a tyre
Publication No. GB190417405 relates to a non-slipping puncture proof jacket consists of steel or other chain mail, B, the links of which increase in size from the tread to the sides of the tyre. Some of the links may be twisted, and the jacket is secured by two wire hoops C slightly larger than the wheel-rim. The referred patent discussed non slipping puncture proof protector of a tyre, but it fails to disclose about self-sealing technology of a tyre.
Publication No. GB190213163 relates to single-tube tyres, or the outer covers of detachable tyres, for the wheels of cycles, motor cars, and other vehicles are protected by securing within the tread part a broad flatsectioned band a of whalebone. The referred patent discussed a broad flat sectioned band for a tyre, but it fails to disclose about self-sealing technology of a tyre.
Publication No. GB189813579 relates to puncture is prevented by overlapping steel shields A 'which are connected together by springs B hooked on to side pieces A<3>. Projections A' overlap the edges of the rim, and the tread is provided with non-slipping circumferential ribs A<4> and transverse ribs A<5>. One spring B<1> is detachable, and the corresponding shield is connected to the rim by a hook C which prevents creeping. The referred patent discussed a puncture-proof non-slipping metallic shield tyre cover, but it fails to disclose about self-sealing technology of a tyre.
Publication No. FR2470015 relates to an unpuncturable chamber into a tyre, the chamber is laid flat against a stop and a strap is wound diametrically around it.. The referred patent discussed a puncture proof resistant chamber into a tyre, but it fails to disclose about self-sealing technology of a tyre.
The article entitled “Segmented hollow puncture-proof tyre” by collection.powerhouse; 30 April 1992 talks about the tyre is the result of a lone inventor solving a problem that he experienced, forming a company to develop and test his idea, protecting the physical form of the idea with patents, and convincing others that the idea was worth investing in, manufacturing and marketing. The referred article disclosed about developing a tyre with hollow rubber segments, which provides more cushioning than solid rubber tyres but is more rugged and has better traction than pneumatic tyres and if a segment is badly damaged, it can be quickly replaced by undoing four bolts, removing the segment, inserting a new one, and tightening the bolts; this can be done without removing the wheel from the vehicle or jacking it up off the ground but it fails to disclose about a self-sealing technology of a tyre.
Thus there is a need for an integrated puncture-seal solution that is embedded within the tyre structure during manufacturing, provides stable adhesion, prevents leakage, and maintains inner liner integrity during curing and service. The present invention addresses these limitations by providing a uniform self sealant layer -liner composite layer incorporated during tyre building. While adding the sealant in building stage it will give the better uniformity and very classic tyre inside appearance (as like a regular tyre) than the applied after curing stage.
In order to overcome above listed prior art, the present invention aims to provide a off-highway tyre (OHT) having an integrated puncture-sealant layer and a manufacturing process involving extrusion of a self sealant layer, preparation of a sealant-liner sandwich structure, and its incorporation during green tyre building.
OBJECTS OF THE INVENTION
The principal object of the present invention is to provide a pneumatic tire construction with enhanced puncture-sealing capability through the incorporation of a self sealant layer and its method of preparation while building of an off high way tyre.
Another object of the present invention is to eliminate self sealant layer migration or penetration to other tyre components during tire building and curing, thereby maintaining structural integrity throughout the manufacturing process.
Yet another object of the present invention is to prevent innerliner cracking by positioning the sealant between two innerliner layers, thus shielding the innerliner from direct exposure
Still another object of the present invention is to provide controlled sealant gauge for predictable and consistent puncture-sealing performance
Yet another object of the present invention is to provide strengthen bonding between the innerliner, sealant, and plies through the sandwich structure, resulting in a more robust and reliable tire construction.
SUMMARY OF THE INVENTION
The present invention relates to a puncture-safe OHT tyre incorporating a sealant layer sandwiched between two innerliner layers. The sealant layer is formed by extruding thick sealant compound directly onto innerliner sheet, supported by a poly film for easy handling. This composite structure is applied centrally on the tyre building drum over the base inner liner, followed by application of a semi cured second innerliner, ply layers, and tread. The resulting tyre exhibits superior puncture-sealing capability, improved adhesion, stable sealant containment, and enhanced innerliner durability.
BRIEF DESCRIPTION OF DRAWINGS
It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered for limiting of its scope, for the invention may admit to other equally effective embodiments.
Fig 1 shows puncture-safe off-highway tyre with integrated puncture-sealant layer, in accordance with the present invention.
Fig 2 shows cured tyre appearance containing a sealant layer, in accordance with the present invention.
DETAILED DESCRIPTION OF THE INVENTION
Various embodiments of the disclosure are discussed in detail below. While specific implementations are discussed, it should be understood that this is done for illustration purposes only. A person skilled in the relevant art will recognize that other components and configurations may be used without parting from the spirit and scope of the disclosure. Thus, the following description and drawings are illustrative and are not to be construed as limiting. Numerous specific details are described to provide a thorough understanding of the disclosure. However, in certain instances, known details are not described in order to avoid obscuring the description.
References to one or an embodiment in the present disclosure can be references to the same embodiment or any embodiment; and, such references mean at least one of the embodiments.
Reference to "one embodiment", "an embodiment", “one aspect”, “some aspects”, “an aspect” means that a particular feature, structure, or Characteristic described in connection with the embodiment is included in at least one embodiment of the disclosure. The appearances of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Moreover, various features are described which may be exhibited by some embodiments and not by others.
The terms used in this specification generally have their ordinary meanings in the art, within the context of the disclosure, and in the specific context where each term is used. Alternative language and synonyms may be used for any one or more of the terms discussed herein, and no special significance should be placed upon whether or not a term is elaborated or discussed herein. In some cases, synonyms for certain terms are provided.
A recital of one or more synonyms does not exclude the use of other synonyms. The use of examples anywhere in this specification including examples of any terms discussed herein is illustrative only, and is not intended to further limit the scope and meaning of the disclosure or of any example term. Likewise, the disclosure is not limited to various embodiments given in this specification. Without intent to limit the scope of the disclosure, examples of instruments, apparatus, methods and their related results according to the embodiments of the present disclosure are given below. Note that titles or subtitles may be used in the examples for convenience of a reader, which in no way should limit the scope of the disclosure. Unless otherwise defined, technical and scientific terms used herein have the meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. In the case of conflict, the present document, including definitions will control.
Additional features and advantages of the disclosure will be set forth in the description which follows, and in part will be obvious from the description, or can be learned by practice of the herein disclosed principles. The features and advantages of the disclosure can be realized and obtained by means of the instruments and combinations particularly pointed out in the appended claims. These and other features of the disclosure will become more fully apparent from the following description and appended claims, or can be learned by the practice of the principles set forth herein.
The present invention provides an off-highway tyre (OHT) having an integrated puncture-sealant layer. The invention provides a manufacturing process involving extrusion of a sealant compound, preparation of a sealant-liner sandwich structure, and its incorporation during green tyre building.
Referring to figure 1, the puncture-safe off-highway tyre comprises a base inner liner layer (1) over the drum; a sealant sandwich layer (3) comprising a thick extruded sealant compound laminated onto inner-liner rubber sheet; a semi cured second inner-liner layer (2) positioned over the sealant sandwich layer; one or more carcass plies (4) applied over the second liner; and a tread package (5) applied over the plies. The sealant sandwich layer is centrally positioned in the crown region of the tyre. Thus the structure comprises:
1. 1st inner-liner (1) having a width of 1.5 mm and it is the innermost layer of a tyre and it is placed over the drum.
2. The 2nd inner-liner layer (2) having a width of 1.0 mm and it is placed above the innermost layer.
3. The self-sealant layer (3) having a width equal to 2nd inner-liner layer and it is placed above the 2nd inner-liner layer.
4. The 3rd inner-liner layer (4) having a width of 1.0 mm and it is over a self-sealant layer and thus 3rd inner-liner layer acts a cover for a self- sealant layer
5. The body ply (5) (carcass/casing layer of a tyre).
A dedicated mini-extruder is used to extrude a puncture-sealant compound. The sealant compound is continuously extruded to form thick layer and is immediately laminated onto rubber inner-liner sheet. The laminated sheet is conveyed on a conveyor system to maintain uniform gauge and alignment.
Sealant compound extrusion takes place in a dedicated mini-extruder. A sealant compound having a 5.0 mm thick, extruder on top of 1 mm inner-liner rubber sheet, is taken through a conveyor. Under the inner liner poly film used for easy handling. This sheet was cut to the desired length and stored in a leaf truck separately.
A poly film is placed beneath the inner-liner to prevent adhesion, ensure smooth handling, avoid distortion, and facilitate storage and transfer. The resulting composite strip is cut to the desired lengths and placed in a leaf truck until use in tyre building.
The method of building green tyre which includes following steps:
Step 1: Application of Base Inner Liner
The tyre-building cycle begins with the application of a base inner-liner layer over the tyre-building drum to form an airtight inner chamber.
A pre-cut sealant sandwich sheet (sealant layer with first inner-liner) is applied centrally over the base inner-liner, aligning with the tyre’s crown region
Step 2: Application of Second innerliner
A second innerliner layer is applied over the sealant sandwich structure. This top innerliner prevents the migration, bleeding, or penetration of sealant gel into other structural layers during the curing process. The Pre vulcanized layers are produced to prepare the second inner layer to prevent the sealant compound penetration inside the plies as well tread.
Step 3: Ply Application and Turn-Up
Multiple carcass plies are applied over the innerliner-sealant assembly. The ply edges are turned up around the bead region and consolidated to form the carcass structure.
Step 4: Tread Application & Final Stitching
The tread package is applied, and the completed green tyre undergoes bottom-stitching to eliminate trapped air and ensure uniform adhesion between layers. The green tyre is subsequently cured using standard curing presses.
Post-Cure Characteristics
The sealant layer cures to a thickness of 3.5–4.0 mm (from an initial green gauge of 5.0–5.5 mm), forming a soft, spongy internal surface. The sealant remains securely bonded between the two innerliner layers and provides consistent puncture-sealing performance. Fig 2 shows cure tyre appearance having a sealant layer with a guage of 3.5 mm to 4 mm and green guage 5 to 5.5mm.
The present invention will be more fully understood from the following examples. These examples are to be constructed as illustrative of the invention and not limitative thereof:
Characterization 1: Hand Nail Test
Tyre Size: 10.0 / 75 – 15.3 10 PR TL
Nail Length – 72mm; Nail Diameter – 3.3 mm
To test in stringent condition, 13 numbers of holes (puncture) were created, and no air leakage was found.
Characterization 2: Air leak Test – Under load
Tyre Size: 10.0 / 75 – 15.3 10 PR TL
Test condition:
Rated Load – 2180 Kg
Test carried at – 500Kg, 1000Kg, 1500Kg, 2000Kg, 2180 Kg & 3000Kg
Air pressure - 60Psi
The load increased up to 40% than rated load and no air leakage was found.
Characterization 3: Static Nail Test
Nail Bed Preparation
In a square plate (480 X 480 mm) holes are created by drilling, 2mm & 2.6mm diameter nails are fixed on a square plate.
Test Procedure:
The tyre was mounted on the rim with 58 psi rated pressure.
Nail punctures were created by using nail bed with deflection machine.
The punctured tyre kept for 24hours observation to evaluate initial sealing Performance.
Standard Tyre - Punctured with nail diameter Ø 2.0 mm at 03 spots.
Sample 1 - Tyre punctured with nail diameter Ø 2.0 mm at 33 spots.
Sample 2 - Tyre punctured with nail diameter Ø 2.6 mm at 160 spots
A soap oil test was conducted to identify any continuous air leakage
Table 1: Static Nail Test - Test Conditions
Parameter Standard Tyre
(without sealant layer) Sample 1
(with sealant layer) Sample 2
(with sealant layer)
Tyre Size 10.0 / 75 – 15.3 10PR TL
Rim Size 9.00 × 15.3 9.00 × 15.3 9.00 × 15.3
Tyre Weight 15.6 kg 17.6 kg 17.6 kg
Sealant layer Not present Present Present
Nail Diameter Ø 2.0 mm Ø 2.0 mm Ø 2.6 mm
Nail Length 35 mm 35 mm 50 mm
Nail pitch 40 mm 40 mm 40 mm
Penetration of Nail 30 mm 30 mm 45 mm
Number of punctures 3 33 160
Puncture creation By Hand By deflection machine By deflection machine
Remarks Leakage No air leakage No air leakage

Results: Table 1A Static Nail Test
Parameter Standard Tyre (without sealant layer) Sample 1
(with sealant layer) Sample 2
(without sealant layer)
Initial Pressure 58 psi 58 psi 58 psi
Final Pressure 0 psi 57.8 psi 57.5 psi
Loss in pressure 58 psi 0.2 psi 0.5 psi

Both the sealant tyres (Sample 1 & 2) are effectively controlled air loss by quickly sealing puncture points and showing no continuous leakages.
Same while the standard tyre experienced immediate and sustained air loss under the same conditions.
Characterization: 4 Static Load test:
Test Procedure:
Punctures tyre was conditioned with 58 psi pressure.
The assembled tyre was mounted in deflection machine with rated load of 1580 Kgs.
Load was increased up to 20% for 24 hrs under loading condition to evaluate initial sealing performance.
The air loss was captured in every load increase, and a soap oil test is conducted to identify any continuous air leakage.
Table 2: Static Leak test – Test Conditions
Parameters Conditions
Inflation Pressure, Psi 58
Standard tyre, number of punctures 03
Sample tyre 1,
number of punctures 33
Sample tyre 2,
number of punctures 160
Static Load, Kg 1550 kg - 1860 kg (20%)
Test Duration, in hours 24 hrs
Leakage Detection Method Soap oil method

Results: Table 2 A Static Load test
Static Load (Kg) Sample 1 – Pressure (Psi) Sample 2 – Pressure (Psi)
1550 58 58
1600 58 58
1650 58 57.6
1700 57.7 57.5
1750 57.7 57.5
1800 57.7 57.1
1860 57.5 57.1

Results: Table 2 B Static Load test
Parameter Standard Tyre Sample 1
(with sealant layer) Sample 2
(with sealant layer)
Initial Pressure 58 psi 58 psi 58 psi
Final Pressure 0 psi 57.5 psi 57 psi
Loss in pressure 58 psi 0.5 psi 1.0 psi

Standard tyre losses the air within 4.2 minutes from the time of load.
Sample 1 & sample 2 sealant tyres are successfully sustained the applied static load with stable pressure retention with minimal loss, whereas the standard tyre was unable to hold the load due to rapid air loss following puncture.
Characterization 4: Air Permeability Test
Test Procedure
A complete, unmounted tire is inflated to a set pressure in a controlled environment to measure pressure loss over time.
The inflated air pressures was monitored and recorded.
Table 3: Air permeability test – Test conditions
Parameter Condition
Inflation Pressure, Psi 58 psi
Rim Size (Rim Diameter X Rim Width) , inches MT 3.50X10
Standard tyre, number of punctures NO
Sample tyre 2,
Number of punctures 160
Ambient temperature, °C 21.7
Test Duration, in Days 11

Results: Table 3A Air permeability test
Parameter Standard Tyre
(without sealant layer & without puncture) Sample tyre 1 (with sealant layer & with 160 punctures)
Initial Pressure, Psi 56.83 56.62
Final Pressure, Psi 56.30 55.96
Test Duration, number of days 11 11
Loss in pressure, Psi 0.50 0.66

Tyre containing sealant layer exhibited controlled and minimal pressure loss over the 11 days test period, comparable to a standard tyre without puncture, demonstrating effective air retention and no rapid air loss after puncture.
Characterization 5: Dynamic Endurance Test
Test Procedure
1. The sealant tyre is moved to dynamic rolling endurance test setup.
2. The tyre tested under dynamic rolling conditions with the specified load applied.
3. Post test inspection and pressure measurement were carried out to confirm sealing effectiveness

Table 4: Dynamic Endurance test - Test Conditions
Parameters Conditions
Inflation Pressure, psi 58
Rim Size (Diameter x Width), inches 9.00 x 15.3
Room temperature, °C 38
Load, Kg 1550
Speed, Kmph 15 kmph
Standard tyre No puncture
Sample tyre 1,
no. of punctures 33

Results: Table 4A Dynamic Endurance test
Parameter Standard Tyre
without sealant layer and without puncture) Sample tyre 1
(with sealant layer and with punctures)
Endurance life, hours 72 72
Initial Pressure, Psi 58 58
Final Pressure, Psi 56.5 56
Loss in pressure, Psi 1.5 2.0
Tyre Section observation No failure No Failure observed and
no cracks on sealant applied area

From the results it is clearly understood that, a tyre containing sealant layer successfully completed 72 hours without failure of dynamic rolling under load with stable pressure retention, demonstrating comparable performance when compared to standard tyre.
Thus, the invention offers several distinct advantages that enhance both performance and durability of the tire. By incorporating a centrally located sealant layer, it provides superior puncture protection, ensuring reliable sealing when the tire is compromised. After curing, the internal surface becomes smooth and spongy, which not only improves handling but also extends the overall lifespan of the tire. The design effectively prevents compound leakage or sealant migration during building and curing, maintaining structural integrity throughout the manufacturing process. Additionally, the placement of the sealant between two innerliner layers protects the innerliner from cracking, further contributing to long-term durability and preventing the migration of puncture sealant compound to tyre surface without puncture. The controlled sealant gauge ensures predictable puncture-sealing performance, offering consistency across different operating conditions. Finally, the sandwich structure enhances bonding between the innerliner, sealant, and plies, resulting in a stronger, more cohesive construction that improves overall tire reliability.
The implementation set forth in the foregoing description do not represent all implementations consistent with the subject matter described herein. Instead, they are merely some examples consistent with aspects related to the described subject matter. Although a few variations have been described in detain above, other modifications or additions are possible. In particular, further features and/or variations can be provided in addition to those set forth herein. For example, the implementation described can be directed to various combinations and sub combinations of the disclosed features and/or combinations and sub combinations of the several further features disclosed above. In addition, the logic flows depicted in the accompany figures and/or described herein do not necessarily require the particular order shown, or sequential order, to achieve desirable results. Other implementations may be within the scope of the following claims.
, Claims:WE Claim:
1. A puncture-safe off-highway tyre comprising:
a) a base inner liner layer (1) positioned over a tyre-building drum;
b) a sealant sandwich layer (3) comprising a thick extruded sealant compound laminated onto an inner-liner rubber sheet;
c) a second liner layer (2) positioned over the sealant sandwich layer;
d) one or more carcass plies (4) applied over the second liner; and
e) a tread package (5) applied over carcass plies,
wherein the sealant sandwich layer is centrally positioned in the crown region of the tyre.
2. The tyre as claimed in Claim 1, wherein the sealant compound is extruded using a dedicated mini-extruder to achieve uniform gauge consistency.
3. The tyre as claimed in Claim 1, wherein a poly film is positioned under the inner-liner sheet to facilitate handling and prevent sticking during transfer.
4. The tyre as claimed in Claim 1, wherein the cured sealant layer has a thickness between 3.5 mm and 4.0 mm.
5. The tyre as claimed in Claim 1, wherein the second liner prevents penetration or bleeding of the sealant compound into carcass plies during curing.
6. A method of manufacturing a puncture-safe off-highway tyre comprising the steps of:
a) extruding a sealant compound to a predetermined thickness laminating the extruded sealant compound onto a 1 mm inner-liner sheet to form a sealant sandwich layer;
b) applying a base inner-liner layer onto a tyre-building drum;
c) applying the sealant sandwich layer centrally over the base inner-liner layer;
d) applying a semi-volcanized second liner layer over the sealant sandwich layer;
e) applying carcass plies and performing turn-up; and
f) applying a tread package and performing bottom-stitching to form the green tyre.
7. The method as claimed in Claim 6, wherein the sealant sandwich layer is cut into predefined lengths and stored in a leaf truck prior to green tyre building.
8. The method as claimed in Claim 6, wherein the cured sealant layer forms a smooth, spongy inner surface with enhanced puncture-sealing capability.