Film to keep tire surface clean and simultaneously prime for better adhesion of balance pad

Abstract

The subject invention relates to a method of preparing a tire inner surface to attain better adhesion of balance pads, puncture sealants, and noise reduction foams. In this method a strip of multi-axially stretchable film is adhered to the inner surface of an uncured tire with a pressure-sensitive adhesive. Then a release agent coating is applied to the film strip on the inner surface of the uncured tire which is subsequently cured in a suitable mold at an elevated temperature. The cured tire is then removed from the mold and after allowing the cured tire to cool the annular circumferential film strip is removed from the inner surface of the tire to provide a circumferential release coating-free tire inner surface onto which balance pads, puncture sealants, and noise reduction foams can be adhered.

Claims

1. A method of balancing a tire which comprises the steps of: providing a cured tire having a release coating-free circumferential inner surface; determining at least one location on the circumference of the release coating-free circumferential inner surface of the cured tire for placement of at least one rubber balance pad to balance the tire; and, adhesively positioning and securing at least one rubber balance pad at the specific location on the circumference of the release coating-free circumferential inner surface of the cured tire; wherein the release coating-free circumferential tire inner surface is prepared by: providing an uncured tire having an inner surface; placing an annular strip of a blend film on a circumferential surface of the inner surface, wherein one end of the strip overlays the other end of the strip to form an interface and is attached to the other end of the strip with a pressure sensitive adhesive at the interface for easy removal of the strip from the inner surface, wherein the blend film: has a thickness in the range of about 50 to about 510 microns (m); has a measured weight in the range of about 2.8 g/84 square inch to about 21.5 g/84 square inch; is formable at a temperature which is within the range of about 121 C. to about 200 C. without tearing; is comprised of approximately between 30% by weight and approximately 70% by weight rubber and approximately between 30% by weight and approximately 70% by weight nylon; and is non-elastomeric in a sense of not returning to its original length when stretched more than about 50 percent of its original length at about 23 C.; applying a release agent coating to the annular, circumferential film strip and the inner surface of the uncured tire; shaping and curing the uncured tire with the release coating on the annular circumferential film strip and inner surface in a suitable mold at an elevated temperature; removing the cured tire from the mold and allowing the cured tire to cool; and, removing the annular circumferential film strip with its release coating to provide a circumferential release coating free tire inner surface of the cured tire.

2. The method of claim 1, wherein the blend film has a thickness of greater than about 150 microns.

3. The method of claim 1, wherein the blend film has a 50% modulus of between about 1 MPa and 10 MPa and a tensile strength of between about 5 MPa and 50 MPa.

4. The method of claim 1, wherein the method further comprises providing a circumferential release coating-free tire inner surface for puncture sealants and noise reduction foams.

5. The method of claim 1 wherein the rubber is natural rubber.

6. The method of claim 5 wherein the nylon is nylon 6.

7. The method of claim 5 wherein the nylon is nylon 6,6.

8. The method of claim 5 wherein the nylon is nylon 12.

9. The method of claim 1 wherein the rubber is butyl rubber.

10. The method of claim 9 wherein the nylon is nylon 6.

11. The method of claim 9 wherein the nylon is nylon 6,6.

12. The method of claim 9 wherein the nylon is nylon 12.

13. A method of balancing a tire which comprises the steps of: (1) providing a cured tire having a removable barrier film; wherein the cured tire is comprised of: (a) a circumferential tread; (b) at least one ply; (c) at least two spaced-apart beads; (d) sidewall portions extending between the tread and the beads; (e) an innerliner, wherein the innerliner lines an inner surface of the at least one ply; and, (f) the removable barrier film, wherein the removable barrier film is positioned along a longitudinal axis of the at least one ply, wherein the removable barrier film is a blend of a rubber and a plasticized nylon, wherein the rubber is selected from the group consisting of natural rubber and butyl rubber, wherein the film is narrower than the innerliner, and wherein one end of the film overlays the other end of the film to provide an overlapping portion with the two ends of the film being secured together with a pressure sensitive adhesive; (2) removing the removable barrier film from the cured tire to produce an unbalanced tire having a release coating-free circumferential inner surface; (3) determining at least one location on the circumference of the release coating-free circumferential inner surface of the cured tire for placement of at least one rubber balance pad to balance the tire; and, (4) adhesively positioning and securing at least one rubber balance pad at the specific location on the circumference of the release coating-free circumferential inner surface of the cured tire.

14. The method of claim 13 wherein the film has a thickness of between about 50 microns and about 510 microns, a 50% modulus of between about 9 MPa and 28 MP, a tensile strength of between about 17 MPa and 41 MPa, wherein the film is comprised of approximately between 30% by weight and approximately 70% by weight rubber and approximately between 30% by weight and approximately 70% by weight nylon.

15. The method of claim 13, wherein the film is a carbon black free extruded film.

16. The method of claim 13, wherein the film has a pull-tab for removal of the film from the innerliner.

17. The method of claim 13, wherein the removable barrier film is superimposed on at least a portion of the innerliner.

18. The method of claim 17, wherein the removable barrier film is superimposed on the surface of the innerliner, wherein the blend film is a combination of butyl rubber, nylon, and N-butylbenzene sulfonamide.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention may take physical form in certain parts and arrangement of parts, at least one embodiment of which will be described in detail in this specification and illustrated in the accompanying drawings which form a part hereof and wherein:

(2) FIG. 1 is a perspective view schematically illustrating positioning of a prepared innerliner (as shown in FIG. 2) on a tire building drum; and,

(3) FIG. 2 is a schematic illustration in a perspective view of a tire carcass with a strip of barrier film long enough to provide a pull-tab, stitched into the innerliner to provide a band of cured virgin innerliner surface within any portion of which a rubbery component may be adhesively secured after the film is removed.

DETAILED DESCRIPTION OF THE INVENTION

(4) Referring now to the drawings wherein the showings are for purposes of illustrating embodiments of the invention only and not for purposes of limiting the same, as shown in FIG. 1, first a narrow blend film 20 is attached to tire building drum 30 where a portion of overlapped film 23 is attached with a pressure sensitive adhesive at the interface. In this embodiment, the film 20 is a carbon black free material. However, it is to be understood that in another embodiment, no adhesive is needed, as the film 20 could be blown into an annular ring construction.

(5) FIG. 2 illustrates a first embodiment of the invention, where there is schematically shown a cross-section of a toroidal tire carcass, referred to generally by reference numeral 10, comprising a circumferential tread 11, spaced beads 12, 12 and connecting sidewall portions 13, 13 (not visible) extending between the tread and beads, to form a conventional cross-bias tire. The carcass 10 includes plural casing plies 14, 15 overlying one another, each having spaced apart parallel reinforcing cords at predetermined angles relative to one another. The inner surface of the innermost belt 14 is lined with a rubber innerliner 16 which is substantially gas-impermeable. The blend film 20 of the present invention, is shown overlying the portion of the surface of the innerliner 16. The components of the tire are assembled on a tire-building drum, the removable blend film 20 being the first component positioned on the drum with a portion overlapped and secured together using a pressure sensitive adhesive.

(6) The green carcass 10 is removed from the drum 30 and stored with the barrier film 20 protecting circumferentially at least a portion of the surface of the innerliner 16. Several days later, the blend film 20 is found to have remained in its original position in the green tire carcass 10. The interior of the carcass 10 is sprayed with lining cement which completely covers the film, and the carcass is placed in a curing press to be conventionally cured. During the conventional curing process, plasticizers and/or other ingredient(s) contained within the blend film 20 migrate onto the innerliner 16. The cured carcass 10 is removed from the press and the film 20 is manually removed in one piece, by pulling on the protruding end of film. The virgin surface, uncontaminated by release agents, but primed by the migration of plasticizers beneath the film is exposed. The migration of plasticizers improves the adhesive properties of the innerliner (as described in greater detail in the background section).

(7) In another embodiment, a strip of barrier film 20 having a width substantially corresponding to the width of the tread 11, is inserted into the carcass 10 and positioned symmetrically about the circumferential center line of the innerliner 16, gently pressing the film 20 against the innerliner 16, so that it is adherently secured to the innerliner 16, and the overlapped portion is attached by a pressure sensitive adhesive. The circumferential edges of the strip 20 are then stitched to the surface of the innerliner 16. The interior of the green carcass 10 with the barrier film 20 in position is then spray-coated with lining cement and the tire cured as before. During the curing process, plasticizers contained within the blend film 20 migrate onto the innerliner 16. When the film 20 is removed, a virgin surface is exposed which is substantially indistinguishable from the virgin surface produced by the prior method of building the tire with the barrier film pre-positioned on the inner-liner, but the latter method is both less cumbersome and less time-consuming.

(8) In another embodiment, a green tire carcass is constructed in a manner analogous to that described above, except that no innerliner is used. The first belt 14 provides the inner surface of an innerliner-free carcass. In a manner analogous to that described for prepositioning the barrier film on the innerliner, the blend film 20 is positioned symmetrically about the longitudinal axis of the first belt 14 and the edges of the film 20 stitched to the rubbery belt. The first belt 14 is then positioned on the building drum so as to provide a pull-tab of film, and construction of the carcass completed in the usual manner. The interior of the green carcass, with the film 20 in position on the innermost belt, is then spray-coated with lining cement and the tire cured as before. During the curing process, plasticizers contained within the blend film 20 migrate onto the innermost belt 16. The cured carcass is removed from the press and the film is manually removed in one piece, by pulling on the protruding end of film. The virgin surface of the innermost belt beneath the film is exposed.

(9) With continuing reference to FIGS. 1 and 2, the building of the tire is accomplished by slipping the blown film cylinder over the tire building drum 30. The carcass 10 is then applied and the two are stitched together. The remaining steps follow the typical tire building process.

(10) The blend film 20 is composed of nylon or plasticized nylon and rubber. In one embodiment, the rubber is at least approximately 30% by weight, and in another embodiment, the rubber is between approximately 30% to approximately 70% by weight, and the nylon is between approximately 30% and approximately 70% by weight. In this embodiment, the rubber can be natural rubber or butyl rubber (polyisobutylene) and the nylon can be nylon 6/66, nylon 6, nylon 6,6, or nylon 12.

(11) An example of the blend film used in this invention is a thermoplastic elastomer from ExxonMobil. The elastomer is at least one halogenated isobutylene-containing elastomer and at least one nylon resin, and a plasticizer suitable for reducing the complex viscosity of the nylon resin. In one example, the isobutylene elastomer is brominated poly (isobutylene-co-p-methylstyrene).

(12) The embodiments have been described, hereinabove. It will be apparent to those skilled in the art that the above methods and apparatuses may incorporate changes and modifications without departing from the general scope of this invention. It is intended to include all such modifications and alterations in so far as they come within the scope of the appended claims or the equivalents thereof.