Pneumatic Object Provided with a Self-Sealing and Gas-Tight Layer Comprising a Thermoplastic Elastomer and Extension Oil
An inflatable article provided with an elastomer layer comprising at least, as major elastomer, a thermoplastic polystirene/polyisobutylene block copolymer, such as a stirene/isobutylene/stirene (SIBS) copolymer, and at least 100 phr of an extender oil. Preferably, this copolymer comprises between 5% and 50% stirene by weight, its number-average molecular weight is between 30,000 and 500,000 g/mol and its Tg is below −20° C. The extender oil is preferably a polybutene oil such as polyisobutylene (PIB) oil. This elastomer layer is able to fulfil not only the role of a self-sealing (puncture-resistant) layer, but also that of an impermeable layer, furthermore with a reduced hysteresis compared to a conventional layer based on butyl rubber. The inflatable article can be, in particular, an inner tube or a pneumatic tire for a motor vehicle.
1 . An inflatable article equipped with a self-sealing elastomer layer impermeable to inflation gases, wherein said elastomer layer comprises at least, as major elastomer, a thermoplastic polystirene/polyisobutylene block copolymer and at least 100 phr of an extender oil.
2 . The inflatable article according to claim 1 , wherein the thermoplastic copolymer is chosen from the group consisting of stirene/isobutylene copolymers, stirene/isobutylene/stirene copolymers and mixtures of these copolymers.
3 . The inflatable article according to claim 2 , wherein the thermoplastic copolymer is a stirene/isobutylene/stirene copolymer.
4 . The inflatable article according to claim 1 , wherein the thermoplastic copolymer comprises between 5 and 50% by weight of stirene.
5 . The inflatable article according to claim 1 , wherein the glass transition temperature of the thermoplastic copolymer is less than −20° C.
6 . The inflatable article according to claim 1 , wherein the number-average molecular weight of the thermoplastic copolymer is between 30,000 and 500,000 g/mol.
7 . The inflatable article according to claim 1 , wherein the extender oil is chosen from the group consisting of polyolefin oils, paraffinic oils, naphthenic oils, aromatic oils, mineral oils, and mixtures of these oils.
8 . The inflatable article according to claim 7 , wherein the extender oil is chosen from the group consisting of polybutene oils.
9 . The inflatable article according to claim 8 , in wherein the extender oil is a polyisobutylene oil.
10 . The inflatable article according to claim 1 , wherein the number-average molecular weight of the extender oil is between 200 and 25,000 g/mol.
11 . The inflatable article according to claim 1 , wherein the content of extender oil is at least equal to 120 phr.
12 . The inflatable article according to claim 11 , wherein the content of extender oil is at least equal to 150 phr.
13 . The inflatable article according to claim 1 , wherein the elastomer layer has a thickness greater than 0.2 mm.
14 . The inflatable article according to claim 13 , wherein in which the elastomer layer has a thickness between 0.3 and 30 mm.
15 . The inflatable article according to claim 1 , wherein the elastomer layer is placed on the inner wall of the inflatable article.
16 . The inflatable article according to claim 1 , wherein said article is made of rubber.
17 . The inflatable article according to claim 16 , wherein said rubber article is a pneumatic tire.
18 . The inflatable article according to claim 16 , wherein said inflatable article is an inner tube.
19 . (canceled)