Methods for retreading tires
A process for retreading a tire, the process comprising the steps of providing a tire casing; providing a cured rubber component having first and second planar surfaces, where the first planar surface includes a tread pattern; providing a cushion gum, wherein the cushion gum is a composition including a functional polymer including at least one functional group, and a crosslinking agent including at least two moieties that will react with the functional group of the functional elastomer; applying the cushion gum to the tire casing; applying the second planar surface of the cured rubber to the cushion gum to form a tire composite; and treating the tire composite to thereby form a retread tire.
1 . A cushion gum comprising:
(i) a rubber component including (a) at least one functional polymer, where the functional polymer includes at least one functional group that is reactive with an amine or an isocyanate, and wherein the at least one functional polymer includes a backbone being a polydiene or a polydiene copolymer having a T g of less than 0° C., and wherein the functional polymer has a number average molecular weight of from 50 kg/mol to 500 kg/mol, and (b) an optional non-functional polymer selected from natural rubber and polymers and copolymers of conjugated dienes, where the cushion gum includes at least 40 percent by weight of the rubber component, and where the weight ratio of the functional polymer to the non-functional polymer is from 1:0 to 1:1;
(ii) at least one crosslinking agent that will react with the at least one functional group of the functional polymer selected from the group consisting of a multi-isocyanate and a multi-amine; and
(iii) at least 25 parts by weight of a reinforcing filler per 100 parts by weight rubber component,
where the cushion gum is configured for adhering a cured tread to a tire casing during a retreading process.
2 . The cushion gum of claim 1 , wherein the at least one functional group is a hydroxyl or organic acid anhydride group.
3 . The cushion gum of claim 2 , wherein the multi-isocyanate is a diisocyanate.
4 . The cushion gum of claim 2 , wherein the multi-amine is a diamine.
5 . The cushion gum of claim 1 , wherein the cushion gum is a cushion gum extrudate.
6 . The cushion gum of claim 1 , wherein the cushion gum is a calendared sheet.
7 . The cushion gum of claim 1 , wherein the cushion gum is in the form of a roll of cushion gum.
8 . The cushion gum of claim 1 , wherein the at least one functional polymer includes a backbone having a T g of less than −20° C.
9 . The cushion gum of claim 1 , wherein the backbone of the functional polymer is chosen from one of polybutadiene, polyisoprene, poly(butadiene-co-isoprene), poly(styrene-co-butadiene), poly(styrene-co-isoprene-co-butadiene), poly(styrene-co-isoprene), and poly(ethylene-co-propylene-co-diene).
10 . The cushion gum of claim 1 , wherein the reinforcing filler is carbon black.
11 . The cushion gum of claim 1 , wherein the cushion gum includes 40 to 90 percent by weight of the rubber component.
12 . The cushion gum of claim 1 , wherein the cushion gum includes 40 to 70 percent by weight of the rubber component.
13 . The cushion gum of claim 1 , wherein the cushion gum includes from 40 to about 60 percent by weight of the rubber component.
14 . The cushion gum of claim 1 , wherein the weight ratio of the functional polymer to the non-functional polymer is from 1:0.1 to 1:0.9.
15 . The cushion gum of claim 1 , wherein the weight ratio of the functional polymer to the non-functional polymer is from 1:0.2 to 1:0.8.
16 . An uncured tire composite comprising:
(i) a tire casing;
(ii) a cured rubber component having first and second planar surfaces, where the first planar surface includes a tread pattern; and
(iii) the cushion gum of claim 1 disposed between the tire casing and the second planar surface of the cured rubber component.
17 . The uncured tire composite of claim 16 , wherein the cushion gum is a cushion gum extrudate.
18 . The uncured tire composite of claim 16 , wherein the cushion gum is a calendared sheet.
19 . A retread tire formed by a process comprising the steps of:
(i) providing a tire casing;
(ii) providing a cured rubber component having first and second planar surfaces, where the first planar surface includes a tread pattern;
(iii) providing the cushion gum of claim 1 ;
(iv) extruding the cushion gum directly on the tire casing to form an extruded cushion gum disposed on the tire casing; and
(v) applying the second planar surface of the cured rubber component to the extruded cushion gum to form a tire composite.
20 . The retread tire of claim 19 , further formed by treating the tire composite to thereby form the retread tire, where said step of treating the tire composite takes place at a temperature of below 110° C.