WO2020115411A1

WO2020115411A1 - Laminate comprising a bonding layer having a radical initiator

Info

Publication number: WO2020115411A1
Application number: PCT/FR2019/052879
Authority: WO
Inventors: Salvatore Pagano; Thomas Ferrand
Original assignee: Compagnie Generale Des Etablissements Michelin
Priority date: 2018-12-03
Filing date: 2019-12-02
Publication date: 2020-06-11
Also published as: CN113165428A; FR3089149A3

Abstract

The invention relates to a laminate for a pneumatic object, comprising at least one layer impermeable to inflation gases, a bonding layer consisting of a composition based on at least one radical initiator selected from peroxo, azo and hydrazyde compounds, a self-sealing layer, said bonding layer being arranged between said layer impermeable to inflation gases and said self-sealing layer.

Description

DESCRIPTION

TITLE: LAMINATE COMPRISING A BINDING LAYER INCLUDING A RADICAL INITIATOR Technical field of the invention

The present invention relates to a laminate for pneumatic object and its preparation process.

Prior art

In general, a pneumatic object such as a pneumatic tire comprises an internal sealing layer delimiting its internal volume. This layer generally comprises a composition based on butyl rubber known to be impermeable to inflation gases such as air. When in use, the pneumatic object may be punctured due to the penetration of a puncturing object, for example a nail or a screw. This perforation causes a leakage of the inflation gases. The loss of pressure following this perforation makes the pneumatic object unusable. In the case of a pneumatic tire, a perforation leads to the flattening of the tire, the stopping of the vehicle and the replacement of the wheel concerned by a spare tire.

In order to solve this puncture problem, one of the many existing solutions consists in adding to the internal wall of the pneumatic object an additional layer of a relatively flexible composition which can flow easily. Thus during a perforation, the composition of the additional layer, due to its flexibility and its ability to flow easily, penetrates into the perforation, closes this perforation and avoids the loss of pressure subsequent to this perforation. Such a composition is called self-sealing (or "self-sealing" in English). The self-sealing compositions are generally associated with the internal sealing layer when making the pneumatic object by using a bonding layer between these two layers. The assembly of these layers forms an elastomeric laminate. Document WO 2009/156049 describes, for example, an airtight and puncture-proof multilayer elastomeric laminate comprising three layers, a first airtight layer based on butyl rubber, a bonding layer consisting of a SIS elastomer (styrene / isobutylene / styrene thermoplastic elastomer) and a self-sealing layer consisting of a SEBS elastomer (thermoplastic elastomer styrene / ethylene / butylene / styrene) and 550 phr of extension oil. Excellent adhesion of the self-sealing layer to the interior of the pneumatic object is obtained, but the manufacture of the laminate requires producing a bonding layer of suitable shape with, for example, an extrusion die.

Thus, there is a need to simplify the method of manufacturing a laminate comprising a layer which is impermeable to inflation gases and a self-sealing layer while seeking to improve the adhesion of the self-sealing layer inside the. pneumatic object.

Continuing her research, the Applicant has discovered a composition of bonding layer allowing excellent adhesion which can be applied in a very simple manner.

The invention and its advantages will be easily understood in the light of the description and of the exemplary embodiments.

Detailed description of the invention

The invention described in detail below relates to at least one of the objects listed in the following points:

1. A laminate for pneumatic objects comprising at least ^:

- a gas-tight inflation layer consisting of a composition based on 50 to 100 phr of at least one diene elastomer and at least one crosslinking system;

- A bonding layer consisting of a composition based on at least one radical initiator chosen from the peroxo, azo, and hydrazydes compounds;

- a self-sealing layer consisting of a composition based on 50 to 100 phr of at least one styrenic thermoplastic elastomer and at least 140 phr of an extension oil;

said bonding layer being disposed between said inflation gas tight layer and said self-sealing layer.

2. A laminate according to the preceding point, in which the diene elastomer of the

composition of the gas-tight inflation layer is chosen from the group consisting of polybutadienes, synthetic polyisoprenes, natural rubber, butadiene copolymers, isoprene copolymers and mixtures of these elastomers.

3. A laminate according to the preceding point, in which the diene elastomer of the

composition of the gas-tight inflation layer is chosen from the group consisting of isoprene and isobutene copolymers, halogenated isoprene and isobutene copolymers, and mixtures of these copolymers. 4. A laminate according to any one of the preceding points, wherein the composition of the inflation gas tight layer further comprises a reinforcing filler.

5. A laminate according to any one of the preceding points, in which the composition of the inflation gas tight layer further comprises a non-reinforcing filler.

6. A laminate according to any one of the preceding points, in which the composition of the tie layer also comprises at least one styrenic thermoplastic elastomer.

7. A laminate according to the previous point, in which the thermoplastic elastomer

styrenic composition of the binding layer is chosen from the group consisting of styrenic thermoplastic elastomers SBS, SIS, SIBS, SEBS, SEPS, SEEPS, and mixtures of these elastomers, and preferably chosen from the group consisting of thermoplastic elastomers SIBS, SEBS, and their mixtures.

8. A laminate according to any of the preceding points, in which the initiator

radical of the composition of the bonding layer is chosen from the group consisting of peroxo compounds and their mixtures, preferably from dicumyl peroxide, 2,5-bis (tert-butylperoxy) -2,5-dimethylhexane, 2, 5-dimethyl-2,5-di (tert-butylperoxy) hexane, and mixtures thereof.

9. A laminate according to any one of the preceding points, in which the bonding layer comprises less than 25% by mass of extension oil, preferably less than 5% by mass, and preferably does not comprise d oil. extension

weight percentages being expressed relative to the mass of binder layer.

10. A laminate according to any one of the preceding points, in which the styrenic thermoplastic elastomer of the composition of the self-sealing layer is chosen from the group consisting of saturated styrenic thermoplastic elastomers and mixtures of these elastomers.

11. A laminate according to the previous point, in which the thermoplastic elastomer

styrene saturated with the composition of the self-sealing layer is chosen from the group consisting of styrene / ethylene / butylene copolymers, styrene / ethylene / propylene copolymers, styrene / ethylene / ethylene / propylene copolymers, styrene / ethylene / copolymers butylene / styrene, copolymers

styrene / ethylene / propylene / styrene, the copolymers

styrene / ethylene / ethylene / propylene / styrene and mixtures of these copolymers.

12. A laminate according to any one of points 1 to 9, in which the elastomer

styrenic thermoplastic of the composition of the self-sealing layer is chosen from the group consisting of unsaturated styrenic thermoplastic elastomers and mixtures of these elastomers. 13. A laminate according to the previous point, in which in which the elastomer

unsaturated styrenic thermoplastic of the composition of the self-sealing layer is chosen from the group consisting of styrene / butadiene copolymers, styrene / isoprene copolymers, styrene / butadiene / butylene copolymers, styrene / butadiene / isoprene copolymers, styrene copolymers / butadiene / styrene,

styrene / butadiene / butylene / styrene copolymers, the copolymers

styrene / isoprene / styrene, styrene / butadiene / isoprene / styrene copolymers and mixtures of these copolymers.

14. A laminate according to any one of the preceding points, in which the oil for extending the composition of the self-sealing layer is chosen from the group consisting of polyolefin oils, paraffin oils, naphthenic oils, aromatic oils, mineral oils, and mixtures of these oils.

15. A laminate according to the preceding point, in which the oil for extending the composition of the self-sealing layer is a polyolefin oil chosen from the group consisting of polybutene oils and mixtures of these oils.

16. A laminate according to the preceding point, in which the oil for extending the composition of the self-sealing layer is chosen from the group consisting of polyisobutylene oils and mixtures of these oils.

17. A laminate according to any one of the preceding points, in which the rate of oil of extension of the composition of the self-sealing layer is included in a range ranging from 140 and 700 phr, preferably from 145 to 600 pce.

18. A laminate according to any one of the preceding points, in which the inflation gas tight layer has a thickness greater than or equal to 0.4 mm, preferably ranging from 0.4 to 2 mm, preferably ranging from 0, 6 to 1.2 mm.

19. A laminate according to any one of the preceding points, in which the self-sealing layer has a thickness greater than or equal to 2 mm, preferably ranging from 2 to 6 mm.

20. A laminate according to any one of the preceding points, in which the layer

inflation gas tight constitutes the internal wall of a pneumatic object, preferably a pneumatic tire.

21. A process for preparing a laminate according to any one of the preceding points, comprising at least ^:

a) A step of preparing a dissolution by complete solubilization of the ingredients of the binding layer in an organic hydrocarbon solvent, the radical initiator representing from 0.1 to 30% by mass of said dissolution and the thermoplastic elastomer, when it is present, representing from 2 to 50% by mass of said dissolution; b) A step of coating by dissolving prepared during step a) of at least one surface chosen from:

the surface of the gas-tight inflation layer intended to be brought into contact with the self-sealing layer, and

- The surface of the self-sealing layer intended to be brought into contact with said gas-tight layer;

c) A step of drying the coated surface at a temperature ranging from 25 to 100 ° C for a period ranging from 0.5 to 24 h;

d) a step of bringing the surface of the gas-tight layer into contact with the surface of the self-sealing layer;

e) A step of baking the laminate obtained at the end of step d).

22. A method according to the preceding point in which the organic hydrocarbon solvent of step a) is an apolar aprotic solvent, preferably chosen from toluene, cyclohexane and dichloromethane, preferably toluene.

23. A process according to any one of points 20 to 22 in which the solution prepared in step a) comprises less than 5% by weight of extension oil.

24. A method according to any one of points 20 to 23 in which step b) of coating is carried out by spraying or brushing.

25. A method according to any one of points 20 to 24 in which the gas-tight layer is the inner wall of a tire.

DEFINITIONS

In the present description, unless expressly indicated otherwise, all the percentages (%) indicated are percentages by mass.

By the expression "composition based on" is meant a composition comprising the mixture and / or the in situ reaction product of the various constituents used, some of these constituents being able to react and / or being intended to react with each other, less partially, during the various stages of manufacturing the composition; the composition thus being able to be in the fully or partially crosslinked state or in the non-crosslinked state.

On the other hand, any range of values designated by the expression "between a and b" represents the range of values going from more than "a" to less than "b" (ie bounds a and b excluded) while any range of values designated by the expression "from a to b" means the range of values from "a" to "b" (that is to say including the strict limits a and b ). When a value is included in a domain, it can take all the values of the domain. So when a value is in a range from a to b, it can take the set of values going from “a” to “b”, that is to say including the values “a” and “b”.

By the expression "part by weight per hundred parts by weight of elastomer" (or phr), it is to be understood for the purposes of the present invention, the part, by mass per hundred parts by mass of elastomers, whether they are thermoplastic or not. In other words, thermoplastic elastomers are elastomers. When a content of a component of a layer or of a mixture is expressed in phr, the mass of elastomers serving as a reference is only the mass of elastomers included in said layer or said mixture.

The compounds comprising carbon mentioned in the description can be of fossil origin or bio-based. In the latter case, they can be, partially or totally, from biomass or obtained from renewable raw materials from biomass. Are concerned in particular polymers, plasticizers, fillers, etc.

Multilayer laminate

A first object of the present invention relates to a laminate for pneumatic object comprising at least ^:

an inflation gas tight layer consisting of a composition based on 50 to 100 phr of at least one diene elastomer, and at least one crosslinking system;

a binding layer consisting of a composition based on at least one radical initiator chosen from peroxo, azo, hydrazydes compounds, and comprising

preferably also at least one styrenic thermoplastic elastomer;

a self-sealing layer consisting of a composition based on 50 to 100 phr of at least one styrenic thermoplastic elastomer and at least 140 phr of an extension oil;

Inflation gas tight layer

The laminate according to the invention comprises at least one layer which is impermeable to inflation gases consisting of a composition based on at least one diene elastomer and at least one crosslinking system, the level of diene elastomer being included in an area ranging from 50 to 100 pc.

Diene elastomer By "diene" elastomer (or indistinctly rubber), whether natural or synthetic, must be understood in known manner an elastomer consisting at least in part (ie, a homopolymer or a copolymer) of diene monomer units (monomers carrying two carbon-carbon double bonds, conjugated or not).

These diene elastomers can be classified into two categories: "essentially unsaturated" or "essentially saturated". In general, the term "essentially unsaturated" means a diene elastomer derived at least in part from conjugated diene monomers, having a proportion of units or units of diene origin (conjugated dienes) which is greater than 15% (% by moles); This is how diene elastomers such as butyl rubbers or copolymers of dienes and alpha-olefins of the EPDM type do not enter into the preceding definition and can be qualified in particular as “essentially saturated” diene elastomers (content of motifs of diene origin weak or very weak, always less than 15%).

The expression “diene elastomer capable of being used in the compositions according to the invention” is particularly understood to mean:

(a) any homopolymer of a diene monomer, conjugated or not, having from 4 to 12 carbon atoms;

(b) any copolymer obtained by copolymerization of one or more dienes conjugated together or with one or more vinylaromatic compounds having from 8 to 20 carbon atoms;

(c) a copolymer of isobutene and isoprene (butyl rubber), as well as the halogenated, in particular chlorinated or brominated, versions of this type of copolymer.

(d) any copolymer obtained by copolymerization of one or more dienes, conjugated or not, with ethylene, a cromolefin or their mixture such as, for example, the elastomers obtained from ethylene, from propylene with a non-conjugated diene monomer of aforementioned type,

Although it applies to any type of elastomer, in particular diene, the skilled person will understand that for use as a layer impermeable to inflation gases, the present invention is preferably implemented with diene elastomers essentially saturated, in particular with elastomers of type (c).

As conjugated dienes, conjugated dienes having from 4 to 12 carbon atoms are suitable, in particular 1.3 dienes, such as in particular 1,3 butadiene and isoprene. Examples of vinyl aromatic compounds are styrene, ortho-, meta-, para-methylstyrene, the commercial "vinyl-toluene" mixture, para-tertiobutylstyrene.

Preferably, the diene elastomer is chosen from the group consisting of polybutadienes (BR), natural rubber (NR), synthetic polyisoprenes (IR), butadiene copolymers, isoprene copolymers, and mixtures of these. elastomers.

Such copolymers are more preferably chosen from the group consisting of isoprene and isobutene copolymers and the blends of these copolymers.

Preferably, the diene elastomer of the composition of the inflation gas tight layer is chosen from the group of isoprene and isobutene copolymers, halogenated copolymers of isoprene and isobutene and mixtures of these copolymers. This type of copolymer is also called butyl rubber.

Examples of butyl rubber which are particularly suitable for use in a layer which is impermeable to inflation gases are ^: copolymers of isobutylene and isoprene (IIR), bromobutyl rubbers such as the bromoisobutylene-isoprene copolymer (BIIR) and chlorobutyl rubbers such as the chloroisobutylene-isoprene copolymer (CIIR).

The level of diene elastomer in the composition of the gas-tight inflation layer is in a range from 50 to 100 phr, preferably in a range from 70 to 100 phr.

Preferably, the level of diene elastomer in the composition of the layer which is impermeable to the inflation gases is within a range from 70 to 100 phr and the diene elastomer is chosen from the group consisting of copolymers of isoprene and d isobutylene, halogenated copolymers of isoprene and isobutylene and mixtures of these copolymers.

Reinforcing filler

The composition of the inflation gas tight layer may further comprise a reinforcing filler. In a known manner, the term “reinforcing filler” is understood to mean a filler known for its capacity to reinforce a rubber composition which can be used for the manufacture of pneumatic objects, such as pneumatic tires. Any type of reinforcing filler can be used, known for its capacity to reinforce a rubber composition which can be used in particular for the manufacture of tires, for example an organic filler such as carbon black, an inorganic filler such as silica or else a mixture of these two types of charges.

As carbon blacks, all carbon blacks are suitable, in particular the blacks conventionally used in tires or their treads. Among the latter, there may be mentioned more particularly the reinforcing carbon blacks of the 100, 200, 300 series, or the blacks of the 500, 600 or 700 series (grades ASTM D-1765-2017), such as for example the blacks N115, N134 N234, N326, N330, N339, N347, N375, N550, N683, N772). These carbon blacks can be used in isolation, as available

commercially, or in any other form, for example as a support for some of the rubber additives used. The carbon blacks could for example already be incorporated into the diene elastomer, in particular isoprene, in the form of a masterbatch (see for example applications WO97 / 36724-A2 or WO99 / 16600-A1).

As an example of organic fillers other than carbon blacks, mention may be made of organic fillers of functionalized polyvinyl as described in applications W02006 / 069792-A1, W02006 / 069793-A1, W02008 / 003434-A1 and W02008 / 003435-A1 .

By "reinforcing inorganic filler" should be understood here any inorganic or mineral filler, whatever its color and its origin (natural or synthetic), also called "white" filler, "clear" filler or even "non-black" filler As opposed to carbon black, capable of reinforcing on its own, without other means than an intermediate coupling agent, a rubber composition intended for the manufacture of tires. In known manner, certain reinforcing inorganic fillers can be characterized in particular by the presence of hydroxyl groups (OH) on their surface.

As reinforcing inorganic fillers, in particular mineral fillers of the siliceous type, preferably silica (S1O ₂ ) or of the aluminous type, in particular alumina (AI2O3), are suitable. The silica used can be any reinforcing silica known to a person skilled in the art, in particular any precipitated or pyrogenic silica having a BET specific surface as well as a CTAB specific surface both of which are less than 450 m 2 / g, preferably included in a range ranging from 30 to 400 m2 / g, in particular from 60 to 300 m2 / g. Any type of precipitated silica can be used, in particular highly dispersible precipitated silicas (called "HDS" for "highly dispersible" or "highly dispersible silica"). These precipitated silicas, highly dispersible or not, are well known from the skilled person. Mention may be made, for example, of the silicas described in applications W003 / 016215-A1 and W003 / 016387-A1. Among the commercial HDS silicas, it is possible in particular to use the “Ultrasil® 5000GR”, “Ultrasil® 7000GR” silicas from the company Evonik, the “Zeosil® 1085GR”, “Zeosil® 1115 MP”, “Zeosil® 1165MP”, “ Zeosil® Premium 200MP ”,“ Zeosil® HRS 1200 MP ”from the company Solvay. As non-HDS silica, the following commercial silicas can be used: “Ultrasil® VN2GR”, “Ultrasil® VN3GR” from Evonik, “Zeosil® 175GR” from Solvay, “ffi” -Sil EZ120G (-D) "," ffi-Sil EZ160G (-D) "," ffi-Sil EZ200G (- D) "," Hi-Sil 243LD "," Hi-Sil 210 "," Hi-Sil HDP 320G ”from PPG.

When the reinforcing filler comprises silica, use is made in known manner of a coupling agent (or bonding agent) at least bifunctional intended to ensure a sufficient connection, of chemical and / or physical nature, between the inorganic filler (surface of its particles) and the diene elastomer. Such coupling agents, in particular

silica / elastomer have been described in a very large number of documents, the best known being bifunctional organosilanes carrying alkoxyl function (that is to say, by definition "alkoxysilanes") and functions capable of reacting with diene elastomer such as for example polysulfide functions.

Other expenses

Preferably, the composition of the gas-tight inflation layer further comprises a non-reinforcing filler (also called an inert filler).

This charge can be in lamellar form.

Preferably, the non-reinforcing filler is chosen from the group consisting of microparticles of natural calcium carbonates (chalk) or synthetic, synthetic or natural silicates (such as kaolin, talc, mica, cloisite), titanium oxides, aluminas, aluminosilicates (clay, bentonite) and mixtures of these fillers.

Preferably, the non-reinforcing filler is chosen from the group consisting of natural or synthetic chalk, talc, kaolin and their mixtures.

Preferably, the composition of the inflation gas tight layer further comprises a semi-reinforcing filler. Semi-reinforcing fillers are not capable of reinforcing on their own a composition comprising a diene elastomer intended for the manufacture of pneumatic tires, in other words they are not capable of replacing, in its reinforcing function, a carbon black conventional pneumatic grade, however they allow an increase in the tensile modulus of a rubber composition in which they are incorporated, this is why they are called "semi-reinforcing". As semi-reinforcing filler which may be present in the composition of the layer which is impermeable to the inflation gases, there may be mentioned in particular graphite.

Crosslinking system

Any type of crosslinking system known to those skilled in the art can be used.

Preferably, the crosslinking system is a vulcanization system. A vulcanization system is a sulfur-based system (or a sulfur-donating agent) and a primary vulcanization accelerator. To this basic vulcanization system can be added, incorporated during the first non-productive phase and / or during the productive phase as described later, various secondary accelerators or known vulcanization activators such as oxide zinc, stearic acid or equivalent compounds.

Inflation gas tight layer thickness

Those skilled in the art will, in the light of the present description, adjust the thickness of the gas-tight inflation layer according to the intended application.

Preferably, the laminate according to the invention comprises at least one layer which is impermeable to inflation gases having a thickness greater than or equal to 0.4 mm. Preferably, the laminate according to the invention comprises at least one layer which is impermeable to inflation gases having a thickness lying in the range from 0.4 to 2 mm, more

preferably between 0.6 to 1.2 mm.

Self-sealing layer

The laminate according to the invention comprises at least one self-sealing layer consisting of a composition based on 50 to 100 phr of at least one elastomer

styrenic thermoplastic and at least 140 phr of an extension oil. The composition of the self-sealing layer is a solid (23 ° C) and elastic compound, which is characterized in particular, thanks to its specific formulation, by very high flexibility and deformability.

Styrenic thermoplastic elastomer

Styrenic thermoplastic elastomers (abbreviated to "TPS") belong, in a known manner, to the family of thermoplastic elastomers (abbreviated to "TPE"). Intermediate structure between thermoplastic polymers and elastomers, they consist of rigid polystyrene blocks linked by flexible elastomer blocks, for example polybutadiene, polyisoprene, poly (ethylene / butylene), or polyisobutylene. They are often triblock elastomers with two rigid segments connected by a flexible segment. The rigid and flexible segments can be arranged linearly, star-shaped or branched. Typically, each of these segments or blocks contains at least more than 5, generally more than 10 base units (for example styrene units and isoprene units for a styrene / isoprene / styrene block copolymer).

By styrene, should be understood in the present description any monomer based on styrene, unsubstituted as substituted; among the substituted styrenes, mention may be made, for example, of methylstyrenes (for example o-methylstyrene, n-methylstyrene, p-methylstyrene, tert-butylstyrene), chlorostyrenes (for example monochlorostyrene, dichlorostyrene).

The number average molecular mass (denoted Mn) of the TPS elastomer is

preferably between 30,000 and 500,000 g / mol, more preferably between 40,000 and 400,000 g / mol. Below the minima indicated, the cohesion between the chains of the elastomer, in particular due to the possible dilution of the latter by an extension oil, risks being affected; on the other hand, an increase in the temperature of use risks affecting the mechanical properties, in particular the properties at break, with the consequence of a reduced performance "when hot". Furthermore, an excessively high mass Mn can be detrimental for the flexibility of the gas-tight layer. Thus, it has been found that a value within a range of 50,000 to 300,000 g / mol is particularly well suited, in particular for use of the composition in a pneumatic tire.

The number average molecular mass (Mn) of the TPS elastomer is determined in known manner by steric exclusion chromatography (SEC). The sample is dissolved beforehand in tetrahydrofuran at a concentration of approximately 1 g / l; then the solution is filtered on a filter with a porosity of 0.45 mih before injection. The apparatus used is a "WATERS alliance" chromatographic chain. The elution solvent is tetrahydrofuran, the flow rate of 0.7 ml / min, the system temperature of 35 ° C and the analysis time of 90 min. We use a set of four WATERS columns in series,

trade names "STYRAGEL" ("HMW7", "HMW6E" and two "HT6E"). The volume injected with the solution of the polymer sample is 100 mΐ. The detector is a "WATERS 2410" differential refractometer and its associated software for processing chromatographic data is the "WATERS MILLENIUM" system. The calculated average molar masses are relative to a calibration curve carried out with polystyrene standards.

The polydispersity index Ip (reminder ^: Ip = Mw / Mn with Mw average molecular weight by weight) of the TPS elastomer is preferably less than 3; more preferably Ip is less than 2.

According to a preferred embodiment of the invention, the weight content of styrene in the TPS elastomer is between 5% and 50%. Below the minimum indicated, the thermoplastic nature of the elastomer may decrease significantly while above the recommended maximum, the elasticity of the composition may be affected. For these reasons, the level of styrene is more preferably between 10% and 40%, in particular between 15 and 35%.

The elastomeric blocks of the TPS for the purposes of the invention may be all the elastomers known to those skilled in the art. They generally have a Tg of less than 25 ° C, preferably less than 10 ° C, more preferably less than 0 ° C and very preferably less than -10 ° C. Also preferentially, the Tg elastomer block of the TPS is greater than -100 ° C.

For carbon chain elastomer blocks, if the elastomer part of the TPS does not contain ethylenic unsaturation, we will speak of a saturated elastomer block. If the TPS elastomer block contains ethylenic unsaturations (that is to say carbon-carbon double bonds), then we will speak of an unsaturated or diene elastomer block.

A saturated elastomer block consists of a polymer block obtained by the polymerization of at least one (that is to say one or more) ethylenic monomer, that is to say comprising a carbon-carbon double bond . Among the blocks derived from these ethylenic monomers, mention may be made of polyalkylene blocks, such as blocks polyisobutylene, polybutylene, polyethylene, polypropylene or else such as random ethylene-propylene or ethylene-butylene copolymers. These saturated elastomeric blocks can also be obtained by hydrogenation of unsaturated elastomeric blocks. It can also be aliphatic blocks from the family of polyethers, polyesters, or polycarbonates.

In the case of saturated elastomeric blocks, this TPS elastomeric block is preferably composed mainly of ethylenic units. By predominantly, is meant a rate by weight of ethylenic monomer which is highest relative to the total weight of the elastomer block, and preferably a rate by weight of more than 50%, more preferably of more than 75% and even more preferably of more than 85 %.

C4-C14 conjugated dienes can be copolymerized with ethylenic monomers. These are random copolymers. Preferably, these conjugated dienes are chosen from isoprene, butadiene, 1-methylbutadiene, 2-methylbutadiene, 2,3-dimethyl-1,3-butadiene, 2,4-dimethyl-1,3 butadiene, 1,3-pentadiene, 2-methyl-1,3-pentadiene, 3-methyl-1,3-pentadiene, 4-methyl-1,3-pentadiene, 2,3-dimethyl-1 , 3-pentadiene, 1,3 hexadiene, 2-methyl-1,3-hexadiene, 3-methyl-1,3-hexadiene, 4-methyl-1,3-hexadiene, 5-methyl-1 , 3-hexadiene, 2,3-dimethyl-1,3-hexadiene, 2,4-dimethyl-1,3-hexadiene, 2,5-dimethyl-1,3-hexadiene, 2-neopentylbutadiene, 1,3-cyclopentadiene, 1,3-cyclohexadiene, 1-vinyl-1,3-cyclohexadiene or a mixture thereof. More preferably, the conjugated diene is chosen from butadiene or isoprene or a mixture containing butadiene and isoprene.

In the case of unsaturated elastomer blocks, this TPE elastomer block is preferably composed mainly of a diene elastomer part. By predominantly, is meant a rate by weight of diene monomer which is highest relative to the total weight of the elastomer block, and preferably a rate by weight of more than 50%, more preferably of more than 75% and even more preferably of more than 85 %. Alternatively, the unsaturation of the unsaturated elastomer block can come from a monomer comprising a double bond and an unsaturation of cyclic type, this is the case for example in polynorbornene.

Preferably, C4-C14 conjugated dienes can be polymerized or copolymerized to constitute a diene elastomer block. Preferably, these conjugated dienes are chosen from isoprene, butadiene, piperylene, 1-methylbutadiene, 2-methylbutadiene, 2,3-dimethyl-1,3-butadiene, 2,4-dimethyl-1 , 3-butadiene, 1,3- pentadiene, 2-methyl-1,3-pentadiene, 3-methyl-1,3-pentadiene, 4-methyl-1,3-pentadiene, 2,3-dimethyl-1,3-pentadiene, 2 , 5-dimethyl-1,3-pentadiene, 2-methyl-1,4-pentadiene, 1,3-hexadiene, 2-methyl-1,3-liexadiene, 2-methyl-1,5-liexadiene , 3-methyl-1,3-liexadiene, 4-methyl1,3-hexadiene, 5-methyl1,3-hexadiene, 2,5-dimethyl-1,3-liexadiene, 2, 5-dimethyl-2,4-liexadiene, 2-neopentyl-1,3-butadiene, 1,3-cyclopentadiene, methylcyclopentadiene, 2-methyl-1,6-lieptadiene, 1,3-cyclohexadiene, -vmyl-1,3-cyclohexadiene or a mixture thereof. More preferably, the conjugated diene is isoprene or butadiene or a mixture containing isoprene and / or butadiene.

Alternatively, the monomers polymerized to form the elastomeric part of the TPS may be copolymerized, statistically, with at least one other monomer so as to form an elastomeric block. According to this variant, the molar fraction of polymerized monomer other than an ethylenic monomer, relative to the total number of units of the elastomer block, must be such that this block retains its elastomer properties.

Preferably, the molar fraction of this other co-monomer can range from 0 to 50%, more preferably from 0 to 45% and even more preferably from 0 to 40%.

By way of illustration, this other monomer capable of copolymerizing with the first monomer can be chosen from ethylenic monomers as defined above (for example ethylene), diene monomers, more particularly, conjugated diene monomers having 4 to 14 carbon atoms as defined above (for example butadiene), the vinylaromatic type monomers having from 8 to 20 carbon atoms as defined below or also, it may be a monomer such as acetate vinyl).

When the co-monomer is of vinylaromatic type, it preferably represents a fraction in units out of the total number of units in the thermoplastic block from 0 to 50%, preferably ranging from 0 to 45% and even more preferably ranging from 0 to 40%. By way of vinyl aromatic compounds, the styrenic monomers mentioned above, namely methylstyrenes, para-tertio-butylstyrene, chlorostyrenes, bromostyrenes, fluorostyrenes or even para-hydroxystyrene, are suitable. Preferably, the vinylaromatic type co-monomer is styrene.

The TPS elastomer can be chosen in particular from the group consisting of saturated block copolymers (in particular: styrene / ethylene / butylene (SEB), styrene / ethylene / propylene (SEP), styrene / ethylene / ethylene / propylene (SEEP), styrene / ethylene / butylene / styrene (SEBS), styrene / ethylene / propylene / styrene (SEPS), styrene / ethylene / ethylene / propylene / styrene (SE EPS), styrene / isobutylene (SIB), styrene / isobutylene / styrene (SIBS)) (including styrene / butadiene (SB), styrene / isoprene (SI), styrene / butadiene / isoprene (SBI), styrene / butadiene / styrene (SBS), styrene / isoprene / styrene (SIS), styrene / butadiene / isoprene / styrene (SBIS), styrene / butadiene / butylene (SBB), styrene / butadiene / butylene / styrene (SBBS)), and mixtures of these copolymers.

Even more preferably, the styrenic thermoplastic elastomer which can be used in the self-sealing compositions in accordance with the invention is a copolymer in which the elastomer part is saturated, and comprising three blocks ^: two styrenic blocks and one alkylene block. The alkylene blocks are preferably ethylene, propylene or butylene. Preferably, this saturated triblock styrenic thermoplastic elastomer is chosen from the group consisting of styrene / ethylene / butylene / styrene copolymers (SEBS), styrene / ethylene / propylene / styrene copolymers (SEPS) and mixtures of these copolymers.

As examples of commercially available styrenic thermoplastic elastomers, mention may be made of the elastomers of the SEPS, SEEPS or SEBS type sold by the company Kraton under the name "Kraton G" (eg products G1650, G1651, G1654, G1633, G1730) or the company Kuraray under the name "Septon" (eg "Septon 2007", "Septon 4033", "Septon 8004").

Extension oil

The composition of the self-sealing layer according to the invention comprises an extension oil (or plasticizing oil), used at a high rate, of at least 140 phr.

It is possible to use, in the present invention, any extension oil, preferably of weakly polar character, capable of extending, plasticizing styrenic thermoplastic elastomers.

At room temperature (23 ° C), these oils, more or less viscous, are liquids (that is to say, substances having the capacity to eventually take the form of their container), in contrast in particular to resins, in particular tackifying, which are by nature solid. Preferably, the extension oil is chosen from the group consisting of polyolefin oils (that is to say derived from the polymerization of olefins, monoolefins or diolefins), paraffinic oils, naphthenic oils (low or high viscosity), aromatic oils, mineral oils, and mixtures of these oils.

More preferably, the extension oil is chosen from the group consisting of polyolefin oils, paraffin oils and mixtures of these oils.

Even more preferably, the extension oil is a polyolefin oil or a mixture of polyolefin oils. This oil demonstrated the best compromise in properties compared to the other oils tested, in particular compared to a conventional oil of the paraffinic type.

Even more preferably, the extension oil is a polyolefin oil chosen from the group consisting of polybutene oils and mixtures of these oils.

Even more preferably, the extension oil is chosen from the group consisting of polyisobutylene oils and mixtures of these oils.

By way of examples, polyisobutylene oils are sold in particular by the company Univar under the name "Dynapak Poly" (eg "Dynapak Poly 190"), by BASF under the names "Glissopal" (eg "Glissopal 1000"), by the company INEOS under the names "H100", "H300", "H1200", "H1500" or "H1900"; paraffinic oils are marketed, for example, by ExxonMobil under the names "Primol 352", "Primol 382" or "Primol 542" or under the names "Flexon815" or "Flexon715".

Preferably, the number-average molar mass (Mn) of the extension oil is less than or equal to 5000 g / mol, and preferably within a range ranging from 300 to 5000 g / mol, more preferably still understood between 350 and 3000 g / mol. For masses Mn of less than 300 g / mol, the latter could migrate outside the self-sealing composition, while excessively high masses could cause excessive stiffening of the self-sealing composition.

The number-average molar mass (Mn), the weight-average molar mass (Mw) and the polydispersity index (Ip) of the extension oil which can be used in the self-sealing compositions in accordance with the invention is determined from known manner by chromatography Size Exclusion ^(SEC: Size Exclusion Chromatography) triple detection as described above.

Preferably, the degree of extension oil is included in a range ranging from 145 to 500 phr, more preferably from 145 to 400 phr, even more preferably from 145 to 350 phr, more preferably from 150 to 350 phr and very preferably from 160 to 350 phr. Below the minimum indicated, the self-sealing composition risks having a stiffness that is too high for certain applications, while beyond the recommended maximum, there is a risk of insufficient cohesion of the self-sealing composition. For this reason, the degree of extension oil is more preferably between 145 and 500 phr, in particular for the use of the self-sealing composition in a pneumatic tire.

A person skilled in the art will know, in the light of the description and of the exemplary embodiments which follow, of adjusting the amount of extension oil according to the particular conditions of use of the self-sealing composition, in particular according to pneumatic object in which it is intended to be used.

Other additives

The self-sealing layer composition according to the invention can also comprise various additives. Typically, these additives are present in small quantities

(preferably at rates lower than 10 phr, more preferentially lower than 5 phr), and are for example, reinforcing fillers such as carbon black, non-reinforcing or inert fillers, protective agents such as anti-UV , antioxidants or anti-ozonants, various other stabilizers, coloring agents

preferably used for coloring the self-sealing composition.

Obtaining the self-sealing layer

The self-sealing layers according to the invention can be obtained in the usual way, for example by incorporating the various components in a br screw extruder or in a paddle mixer, in particular with Z paddles.

A first conventional way of obtaining the self-sealing layers in accordance with the invention consists in incorporating the styrenic thermoplastic elastomer and the extension oil in a brvis extruder equipped with a sufficient number of conveying, shearing and retention so as to achieve the fusion of the elastomer matrix and incorporation of the extension oil. The brvis extruder can be anything type of brvis extruder whose L / D ratio between the length and the diameter of the screw is in a range from 20 to 40, equipped with a hopper for feeding the styrenic thermoplastic elastomer and at least d '' a pressurized liquid injection pump for the extension oil. At the point of introduction of the styrenic thermoplastic elastomer, the temperature is close to room temperature (23 ° C). It is then brought further along the screw to a value substantially higher than the melting temperature of the retained styrenic thermoplastic elastomer and is included in a range from 220 to 290 ° C. At the point of introduction of the extension oil, the temperature is also within a range from 220 to 290 ° C. At the point of exit from the extruder, the temperature is in a range from 110 to 170 ° C.

The extruder is provided at its outlet with a die for shaping the product to the desired dimensions. The overall output flow is in a range from 3 to 10 kg / h. With a cylindrical die, one obtains a rod whose diameter is included in a range going from 10 to 20 mm. With a flat die, a strip (profile) is obtained whose thickness is in the range from 1 to 3 mm and whose width is in the range from 20 to 250.

When using styrenic thermoplastic elastomers such as SEPS or SEBS already extended with high levels of oils, the step of mixing the TPS and the extension oil can be omitted. The already extensive styrenic thermoplastic elastomers are well known and commercially available. By way of examples, mention may be made of the products marketed by the company Hexpol TPE under the name "Dryflex" (e.g.

"Dryflex 967100") or "Mediprene" (e.g. "Mediprene 500 000M"), those sold by Multibase under the name "Multiflex" (e.g. "Multiflex G00").

Another conventional way of obtaining the self-sealing layers according to the invention consists in the use of a mixer with blades Z, for example of the type MK LU 1 from the company Linden with a useful capacity of one liter. , in which are loaded the styrenic thermoplastic elastomer and the extension oil. The mixer tank is heated so that the mixture reaches a temperature in the range of 80 to 140 ° C depending on the number of ingredients used. The speed of the blades is selected in a range from 10 to 100 rpm and the mixing time is chosen in a range from 30 min to 24 hours. A person skilled in the art knows how to adjust each of these parameters in order to obtain a homogeneous mixture which will then be used as a self-sealing layer. In this case, a "batch" is obtained which does not exhibit any particular shaping. Bonding layer

The laminate in accordance with the invention comprises at least one bonding layer consisting of a composition based on at least one radical initiator chosen from peroxo, azo and hydrazide compounds, and preferably also comprising at least one thermoplastic elastomer styrenic.

Radical initiator

The composition of the bonding layer comprises at least one radical initiator chosen from the peroxo, azo and hydrazydes compounds. Preferably, the radical initiator is chosen from the group consisting of peroxo compounds and their mixtures,

preferably from dicumyl peroxide, 2,5-bis (tert-butylperoxy) -2.5

dimethylhexane and 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane and their mixtures.

When the bonding layer comprises at least one styrenic thermoplastic elastomer, the content of free radical initiator is preferably between 0.2 and 1500 phr, preferably between 1 and 700 phr, very preferably between 1 and 200 phr and very preferably between 1 and 150 phr.

Surprisingly, the presence of a bonding layer comprising a radical initiator makes it possible to improve the adhesion of the self-sealing layer to the gas-tight layer.

Extension oil

The composition of the binding layer may comprise an extension oil as defined above. Preferably, the bonding layer comprises less than 25% of extension oil, preferably less than 5%, and preferably does not comprise extension oil, the percentages being expressed relative to the mass of tie layer. When the bonding layer comprises at least one styrenic thermoplastic elastomer, the content of extension oil is preferably less than 25 phr, preferably less than 5 phr, and very preferably the bonding layer does not comprise oil extension.

Styrenic thermoplastic elastomer

The composition of the bonding layer preferably comprises at least one styrenic thermoplastic elastomer as defined previously in the present description. Preferably, the composition of the tie layer comprises at least one styrenic thermoplastic elastomer chosen from the group consisting of the styrenic thermoplastic elastomers SBS, SIS, SIBS, SEBS, SEPS, SEEPS and mixtures of these elastomers, and preferably chosen from the group consisting of the thermoplastic elastomers SIBS and SEBS and their mixtures.

Preparation process

The invention also relates to a process for the preparation of a laminate as described above.

The process for preparing a laminate comprising a layer which is impermeable to inflation gases, a bonding layer and a self-sealing layer according to the invention comprises at least the following steps:

a) A step of preparing a dissolution by complete solubilization of the ingredients of the bonding layer in an organic hydrocarbon solvent, the radical initiator representing from 0.1 to 30% by mass of said dissolution and the thermoplastic elastomer, when it is present, representing from 2 to 50% by mass of said dissolution;

b) A step of coating by dissolution prepared during step a) of at least one surface chosen from:

the surface of the inflation gas tight layer intended to be brought into contact with the self-sealing layer, and

the surface of the self-sealing layer intended to be brought into contact with said gas-tight layer;

e) A step of baking the laminate obtained at the end of step d).

The term dissolution denotes herein the mixture obtained at the end of step a) by complete solubilization of the ingredients of the binding layer in an organic hydrocarbon solvent.

Preferably, the organic hydrocarbon solvent of step a) is an apolar aprotic solvent, preferably chosen from toluene, cyclohexane and

dichloromethane, preferably toluene. Preferably, the dissolution prepared in step a) of the process according to the invention comprises less than 5% of extension oil, this percentage being expressed relative to the total mass of the dissolution.

Step b) of the method according to the invention can be carried out by any means known to the skilled person. Preferably, this step is carried out by spraying, or by brushing, for example with a brush, or any other means making it possible to uniformly distribute a liquid layer.

Step c) of drying is carried out at a temperature ranging from 25 to 100 ° C for a duration ranging from 0.5 to 24 h. The higher the temperature, the more the drying time can be reduced. Thus, a duration of 0.5 h will be sufficient if the drying temperature is 100 ° C while a duration of 24 h may be necessary if the drying temperature is 25 ° C.

In step d), the surface of the gas-tight inflation layer intended to be brought into contact with the self-sealing layer is brought into contact with the surface of the self-sealing layer intended to be brought into contact with the inflation gas tight layer.

Preferably, the gas-tight layer is the internal wall of a tire.

In this case, the steps of the preparation process according to the invention can be carried out on a confection drum. The examples which follow illustrate the invention without however limiting it.

Examples

Preparation of the compositions

The following different layers are prepared which are then assembled to form a laminate, the adhesion of the self-sealing layer to the gas-tight layer via the bonding layer will be tested by a peel test.

Inflation gas tight layer

The inflation gas tight layer consists of the composition C1, the details of which are given in Table 1. The rates are expressed in phr.

[Table l]

(a) Brominated butyl rubber sold under the reference Bromobutyle 7211 by the company ExxonMobil;

(b) N770 carbon black sold by Cabot Corporation;

(c) Mercaptobenzothiazyl disulfide sold under the reference MBTS MG by the company Akrochem.

The layers impermeable to the inflation gases are prepared according to the following method.

Is introduced into an internal mixer, filled to 70% and whose initial tank temperature is around 60 ° C, successively carbon black, butyl rubber and various other possible ingredients with the exception of the vulcanization system. Thermomechanical work (non-productive phase) is then carried out in one step, which lasts a total of approximately 3 to 4 minutes, until a maximum "fall" temperature of 150 ° C is reached.

The mixture thus obtained is recovered, it is cooled then the sulfur and the accelerator are incorporated on an external mixer (homo-fmisseur) at 30 ° C, mixing everything (productive phase) for an appropriate time (for example between 5 and 12 min).

The composition obtained at the end of the productive phase is then calendered in the form of thin sheets of length 150 mm, width 150 mm and thickness 2 mm.

Binding layer dissolution

The solutions DI to D4, the compositions of which are indicated in Table 2, are prepared in the following manner: the TPS is dissolved, when it is present, in toluene at room temperature. Once the solution is well homogeneous, the radical initiator is added to the toluene / TPS solution. When there is no TPS, the radical initiator is directly added to toluene and the solution homogenized. [Table 2]

(a) Styrenic thermoplastic elastomer (TPS) ^: styrene / ethylene / butylene / styrene block copolymer SEBS sold by the company Kraton under the reference G1654;

Mn = 116,000 g / mol and Ip = 1.1; Mn and Ip measured according to the method described in the description.

(b) LuperoxlOl® from the company Arkema Self-sealing layer

The self-sealing layer consists of a composition B1, the details of which are given in Table 3. The rates are expressed in pce.

[Table 3]

(b) Extension oil: Polyisobutylene oil sold by the company Univar under the reference Dynapak 190; Mn = 1000 g / mol and Ip = 1.4; Mn and Ip measured according to the method described in the description.

The self-sealing layer consisting of composition B1 is prepared in a conventional manner by one-step extrusion of the styrenic thermoplastic elastomer and the extension oil.

The styrenic thermoplastic elastomer and the extension oil are introduced into a brvis L / D = 40 extruder via a feed hopper for the elastomer and a pressurized liquid injection pump for the extension oil. The brvis extruder is provided a flat die for extruding the product to the desired dimensions. The temperature at the point of introduction of the thermoplastic elastomer is at room temperature (23 ° C). It is then carried further along the screw to a value

substantially higher than the melting temperature of the retained styrenic thermoplastic elastomer, at approximately 275 ° C. At the point of introduction of the oil, the temperature is also around 275 ° C. At the point of exit from the extruder, the temperature is about 140 ° C. The overall flow is included at the outlet is 4 kg / h. This extruder is equipped with a flat die which makes it possible to obtain a profile of the following dimensions ^: length 150 mm, width 150 mm and thickness 2 mm.

Preparation of the peeling test pieces

The multilayer laminates are tested for adhesion of the bonding layer to the crosslinked gas-tight layer according to a so-called peel test.

The peeling test pieces of the 180 ° peeling type are produced in the following manner: Two sheets of a gas-tight inflation layer of dimensions 150 mm by 150 mm and thickness 2 mm are coated on one side by dissolving tie layer. A sheet of self-sealing layer with a thickness of 3 mm and dimensions 150 mm by 150 mm is coated on both sides by the dissolution of the bonding layer. The surfaces thus coated are left to dry at room temperature for 12 h.

A laminate is then produced by successively stacking an inflation gas tight layer, a self-sealing layer and the second inflation gas tight layer, the coated faces of the inflation gas tight layers being brought into contact with the coated faces. the self-sealing layer.

On one side of this stack, a rupture primer is inserted between the sheet of gas-tight inflation layer and the bonding layer. The dimensions of the primer are: width 20 mm and length 150 mm. This stack is placed under a press and cooked at a pressure of 1.6 MPa and a temperature of 170 ° C applied for 13 minutes.

Peeling specimens are obtained by cutting strips of laminate 30 mm wide and 150 mm long with a guillotine, taking care to have the primer at one end of the specimen.

The two sides of the fracture leader were then placed in the jaws of an Instron brand traction machine. (Model 5569). The peel measurement is carried out by pulling 180 ° and at a speed of 100 mm / min at a temperature of 23 ° C. The tensile forces are recorded and these are normalized by the width of the test piece. A force curve is obtained per unit of width (in N / mm) as a function of the displacement of the mobile cross member of the traction machine (between 0 and 150 mm). The adhesion value adopted corresponds to the initiation of the rupture within the test piece and therefore to the maximum value of this curve.

Test

The purpose of this test is to demonstrate that a laminate in accordance with the invention has improved adhesion properties compared to the laminate produced without a bonding layer, in which the self-sealing layer is brought directly into contact with the waterproof layer. inflation gases.

The multilayer laminates STI, and SI1 to SI4 are prepared and a measurement of the adhesion is carried out as presented above. The structure of the laminates and the results of the peel test are presented in Table 4.

The STI laminate not in accordance with the invention is prepared with a gas-tight inflation layer on which the self-sealing layer has been deposited.

The laminates SI1 to SI4, in accordance with the invention, differ from the STI laminate not in accordance with the invention by the formulation of the composition of the bonding layer.

[Table 4]

The results of the peel test are presented in base 100, taking as reference the results obtained with the laminate not comprising an STI bonding layer.

A much better adhesion of the self-sealing layer to the gas-tight inflation layer via the bonding layer is observed with the laminates according to the invention.

Claims

[Claim 1] Laminate for pneumatic object comprising at least ^:

a binding layer consisting of a composition based on at least one radical initiator chosen from the peroxo, azo and hydrazydes compounds;

a self-sealing layer consisting of a composition based on 50 to

100 phr of at least one styrenic thermoplastic elastomer and at least 140 phr of an extension oil;

[Claim 2] A laminate according to the preceding claim, in which the diene elastomer of the composition of the gas-tight layer for inflation is chosen from the group consisting of polybutadienes, synthetic polyisoprenes, natural rubber, butadiene copolymers , isoprene copolymers and mixtures of these elastomers.

[Claim 3] A laminate according to the preceding claim, in which the diene elastomer of the composition of the gas-tight layer for inflation is chosen from the group consisting of isoprene and isobutene copolymers, halogenated isoprene copolymers and isobutene, and mixtures of these copolymers.

[Claim 4] A laminate according to any one of the preceding claims, wherein the composition of the inflation gas tight layer further comprises a reinforcing filler.

[Claim 5] A laminate according to any one of the preceding claims, wherein the composition of the tie layer also comprises at least one styrenic thermoplastic elastomer.

[Claim 6] A laminate according to the preceding claim, wherein the styrenic thermoplastic elastomer of the composition of the bonding layer is chosen from the group consisting of styrenic thermoplastic elastomers SBS, SIS, SIBS, SEBS, SEPS, SEEPS, and mixtures of these elastomers, and preferably chosen from the group constituted by the thermoplastic elastomers SIBS, SEBS, and their mixtures.

[Claim 7] A laminate according to any one of the preceding claims, in which the radical initiator of the composition of the binding layer is chosen from the group consisting of peroxo compounds and their mixtures, preferably from dicumyl peroxide, 2 , 5- bis (tert-butylperoxy) -2,5-dimethylhexane, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane, and mixtures thereof.

[Claim 8] A laminate according to any one of the preceding claims, wherein the styrenic thermoplastic elastomer of the composition of the self-sealing layer is selected from the group consisting of saturated styrenic thermoplastic elastomers and mixtures of these elastomers.

[Claim 9] A laminate according to any one of claims 1 to 7, in which the styrenic thermoplastic elastomer of the composition of the self-sealing layer is chosen from the group consisting of unsaturated styrenic thermoplastic elastomers and mixtures of these elastomers .

[Claim 10] A laminate according to any one of the preceding claims, in which the oil for extending the composition of the self-sealing layer is chosen from the group consisting of polyolefin oils, paraffin oils, naphthenic oils, aromatic oils, mineral oils, and mixtures of these oils.

[Claim 11] A laminate according to the preceding claim, wherein the oil

for extending the composition of the self-sealing layer is a polyolefin oil chosen from the group consisting of polybutene oils and mixtures of these oils, preferably chosen from the group consisting of polyisobutylene oils and mixtures of these oils.

[Claim 12] A laminate according to any one of the preceding claims, in which the self-sealing layer has a thickness greater than or equal to 2 mm, preferably ranging from 2 to 6 mm.

[Claim 13] A laminate according to any one of the preceding claims, in which the inflation gas tight layer constitutes the internal wall of a pneumatic object, preferably a pneumatic tire. [Claim 14] Process for the preparation of a laminate according to any one of the preceding claims, comprising at least ^:

a) A step of preparing a dissolution by complete solubilization of the ingredients of the binding layer in an organic hydrocarbon solvent, the radical initiator representing from 0.1 to

30% by mass of said dissolution and the thermoplastic elastomer, when present, representing from 2 to 50% by mass of said dissolution;

c) A step of drying the coated surface at a temperature ranging from 25 to 100 ° C for a period ranging from 0.5 to 24 h; d) a step of bringing the surface of the gas-tight layer into contact with the surface of the self-sealing layer;

e) A step of baking the laminate obtained at the end of step d). [Claim 15] Method according to the preceding claim wherein the solvent

organic hydrocarbon of step a) is an apolar aprotic solvent, preferably chosen from toluene, cyclohexane and

dichloromethane, preferably toluene.