US-12623424-B2 - Method for adhering cured rubber components

Abstract

A method for preparing a retreaded tire, the method comprising (a) providing a tire casing; (b) providing a pre-cured tire tread; (c) applying a primer composition to the tire casing, the pre-cured tread, or both the tire casing and the pre-cured tread therefore form at least one primer layer, where the primer composition includes a halogenating agent and a solvent; (d) applying a urethane-based adhesive composition to at least one of the tire casing, an adhesive layer, the pre-cured tread, or the at least one primer layer; (e) mating the pre-cured tread to the tire casing to thereby sandwich the adhesive layer between the pre-cured tread and the tire casing and form a pre-cured composite: and (f) allowing the adhesive layer of the pre-cured composite to cure and thereby form a retreaded tire.

Inventors

• Vishal K. CHAURASIA
• Yenni Marcela CASTANO GIL
• Kung-Ching LIAO
• Kentaro KAYASHIMA

Assignees

• BRIDGESTONE AMERICAS TIRE OPERATIONS, LLC

Dates

Publication Date

20260512

Application Date

20221228

Claims (13)

1. 1 . A method for preparing a retreaded tire, the method comprising: a. providing a tire casing, where the tire casing includes natural rubber and styrene butadiene rubber; b. providing a pre-cured tire tread where the pre-cured tire tread includes natural rubber and styrene butadiene rubber; c. preparing a primer composition, where the primer composition includes (i) trichloroisocyanuric acid and water, or (ii) sodium dichloroisocyanurate and ethanol; d. applying multiple layers of the primer composition to the tire casing, the pre-cured tread, or both the tire casing and the pre-cured tread to thereby form a multilayer primer coating, where said step of applying includes (i) applying at least ten layers where the primer composition includes trichloroisocyanuric acid and water, or (ii) applying at least seven layers where the primer composition includes sodium dichloroisocyanurate and ethanol; e. applying a urethane-based adhesive composition to at least one of the tire casing, the pre-cured tread, and the multilayer primer coating to form an adhesive layer; f. mating the pre-cured tread to the tire casing to thereby sandwich the adhesive layer between the pre-cured tread and the tire casing and form a pre-cured composite; and g. allowing the adhesive layer of the pre-cured composite to cure and thereby form a retreaded tire, where said step of allowing the adhesive layer of the composite to cure takes place at a temperature of less than 80° C.
2. 2 . The method of claim 1 , where the tire casing includes a radially outward facing surface, and where the primer composition is applied to the radially outward facing surface of the tire casing.
3. 3 . The method of claim 1 , where the pre-cured tread includes a radially inward facing surface, and where the primer composition is applied to the radially inward facing surface of the tread.
4. 4 . The method of claim 1 , where the adhesive composition is a two-part polyurethane adhesive.
5. 5 . The method of claim 1 , where said step of allowing the adhesive layer to cure takes place at pressures of less than 100 PSI relative to atmospheric pressure.
6. 6 . The method of claim 1 , where said step of allowing the adhesive layer to cure takes place without applying pressure on the urethane-based adhesive composition.
7. 7 . The method of claim 1 , where the retreaded tire is a pneumatic tire.
8. 8 . The method of claim 1 , where the primer composition has a solids content of less than 10 wt %.
9. 9 . The method of claim 8 , where each layer of the multiple layers has a thickness of greater than 1 μm, where the thickness refers to the wet thickness of each layer.
10. 10 . The method of claim 1 , where said urethane-based adhesive composition has a viscosity in the range of about 1,500 to about 4,500 cPs.
11. 11 . The method of claim 1 , where said step of applying multiple layers of the primer composition includes allowing each layer of the multiple layers to dry for at least one minute before applying a subsequent layer.
12. 12 . The method of claim 1 , where said applying takes place within two days of said preparing a primer composition.
13. 13 . The method of claim 1 , where the tire casing includes a rubber component consisting of natural rubber and styrene butadiene rubber, and where the pre-cured tire tread includes a rubber component consisting of natural rubber and styrene butadiene rubber.

Description

This application claims the benefit of U.S. Provisional Application Ser. Nos. 63/294,629 and 63/294,641 filed on Dec. 29, 2021, which are incorporated herein by reference. FIELD OF THE INVENTION Embodiments of the invention are directed toward methods for retreading tires by employing a polyurethane adhesive to bond a cured tread element to a tire casing. Other embodiments of the invention relate to a rubber treatment composition and method of using the composition to facilitate adhering cured rubber components. In particular embodiments, the invention includes a method retreading a tire by using the rubber treatment composition in combination with a urethane adhesive. BACKGROUND OF THE INVENTION The bonding of vulcanized rubber components to vulcanized rubber substrates is technologically important. For example, in tire retreading processes, pre-cured tire treads are adhered to a tire casing, which is often prepared by removing a worn tread from a used tire. The pre-cured or vulcanized replacement tread is adhesively attached to a crown portion of the tire casing, which may also be referred to as a base tire. Many commercially useful retreading processes employ a cushion gum to adhesively attach or bond the pre-cured tread to the tire casing. The cushion gum includes green or uncured rubber and a rubber curing agent. Upon formation of the composite (i.e. placement of the tread onto the tire casing with the cushion sandwiched there between), the composite is subjected to heat and pressure to thereby vulcanize the cushion gum and adhere the tread to the casing. Retreading processes have been proposed that adhesively mate vulcanized tread to tire casing at ambient or relatively low temperatures. For example, European Patent Application No. 0 316 666 teaches a retreading process that includes the use of an amine-curable polymer or pre-polymer to adhere a pre-cured tire tread to a tire casing. Prior to applying adhesive composition to the tread or tire casing, a treating agent can be applied to the cured rubber in order to activate the cured rubber surface and allow the amine-curable polymer to bond therewith. The treating agent is a halogen-containing oxidant, such as trichloro-S-triazinetrione, that is applied to the cured rubber as a liquid or solution dissolved in an inert solvent such as butyl acetate. While retreading processes that employ ambient or relatively low-temperature cure systems are environmentally beneficial, the current ambient or low-temperature technologies have several shortcomings. SUMMARY OF THE INVENTION One or more embodiments of the present invention provide a method for preparing a retreaded tire, the method comprising (a) providing a tire casing; (b) providing a pre-cured tire tread; (c) applying a primer composition to the tire casing, the pre-cured tread, or both the tire casing and the pre-cured tread therefore form at least one primer layer, where the primer composition includes a halogenating agent and a solvent; (d) applying a urethane-based adhesive composition to at least one of the tire casing, an adhesive layer, the pre-cured tread, or the at least one primer layer; (e) mating the pre-cured tread to the tire casing to thereby sandwich the adhesive layer between the pre-cured tread and the tire casing and form a pre-cured composite: and (f) allowing the adhesive layer of the pre-cured composite to cure and thereby form a retreaded tire. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flow chart showing the method of retreading a tire according to one or more embodiments of the invention. FIG. 2 is a graphical representation of experimental results obtained from testing done on samples prepared in accordance with the present invention. FIGS. 3a and 3b are graphical representations of experimental results obtained from testing done on samples prepared in accordance with the present invention DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS Embodiments of the present invention are based, at least in part, upon the discovery of an ambient or low-temperature rubber adhering process that employs a urethane-based adhesive. In one or more embodiments, the invention includes a method whereby at least one cured rubber substrate is primed with a treating agent prior to being adhered with the urethane-based adhesive. And, it has been found that unexpected results are obtained when a threshold number of coating layers of the treating agent are applied to the substrate. In particular embodiments, the treating agent composition includes water and/or alcohol as a solvent. Given the limited solubility of the treating agents within water and/or alcohols, the ability to retread tires using these treating agents was unexpected. In one or more embodiments, the present invention is directed toward a tire retreading process where a pre-cured rubber tread is adhered to a base tire at low temperatures by treating at least one of the rubber surfaces with the treating agent composition and the adhering