FR3060012A1 - PNEUMATIC HAVING A COMPOSITION COMPRISING A DIENE ELASTOMER, A ZINC ACRYLATE, A PEROXIDE AND A SPECIFIC ANTIOXIDANT - Google Patents

Abstract

The invention relates to a tire comprising a rubber composition having improved cohesion and resistance to crack propagation, said composition being based on at least one diene elastomer; a peroxide; a zinc diacrylate derivative in the form of a specific zinc salt; a specific phenolic derivative; a metal oxide selected from the group consisting of Group II, IV, V, VI, VII and VIII metal oxides, and mixtures thereof; the levels of zinc diacrylate derivative and of peroxide being such that the ratio of the level of peroxide and the level of zinc diacrylate derivative is less than or equal to 0.09.

Description

Holder (s): COMPAGNIE GENERALE DES ETABLISSEMENTS MICHELIN Limited partnership with shares, MICHELIN RECHERCHE ET TECHNIQUE S.A. Limited company.

Extension request (s)

Agent (s): MANUFACTURE FRANÇAISE DES PNEUMATIQUES MICHELIN.

TIRE PROVIDED WITH A COMPOSITION COMPRISING A DIENE ELASTOMER, A ZINC ACRYLATE, A PEROXIDE AND A SPECIFIC ANTI-OXIDANT.

FR 3 060 012 - A1 tüy) The invention relates to a tire comprising a rubber composition having improved cohesion and resistance to crack propagation, said composition being based on at least one diene elastomer; a peroxide; a zinc diacrylate derivative in the form of a specific zinc salt; a specific phenolic derivative; a metal oxide chosen from the group consisting of the oxides of the metals of groups II, IV, V, VI, VII and VIII, and their mixtures; the levels of zinc diacrylate derivative and peroxide being such that the ratio of the peroxide level and the rate of zinc diacrylate derivative is less than or equal to 0.09.

The invention relates to tires and more particularly to those in which the composition of an inner layer comprises a derivative of zinc diacrylate, a peroxide and a specific antioxidant.

Tire layers such as the tread or the inner layers must comply with a large number of technical requirements, often contradictory, including good rigidity, good cohesion and good resistance to crack propagation.

Tire designers are constantly looking for a solution which allows the existing compromise in properties to be improved by improving at least one property of the tire, without penalizing the others.

Systems usually used to stiffen a rubber mixture are on the one hand vulcanization and on the other hand the introduction of reinforcing filler. However, these solutions can induce a decrease in cohesion and resistance to cracking.

It is in this context that the Applicants have surprisingly discovered that the use of a zinc diacrylate derivative and a peroxide in combination with a specific phenolic derivative antioxidant makes it possible to improve cohesion and resistance to crack propagation, without penalizing the stiffness.

Thus, the subject of the present invention is in particular a tire comprising a rubber composition based on at least:

a diene elastomer, a peroxide, a derivative of zinc diacrylate in the form of a zinc salt of formula (I) r ₂ oor ₂

(l)

-2 in which R ^ R ₂ and R ₃ independently of one another represent a hydrogen atom or a C1-C7 hydrocarbon group chosen from linear, branched or cyclic alkyl groups, aralkyl groups, alkylaryl groups and groups aryls, and possibly interrupted by one or more heteroatoms, R ₂ and R _{3 being} able to form together a non-aromatic ring, a phenolic derivative of formula (II)

(II) in which:

o A! represents a linear or branched C1-C4 alkyl group, optionally substituted by a carboxylate of a hydrocarbon group comprising 1 to 60 carbon atoms and optionally oxygen atoms;

o A ₂ represents a hydrogen atom or a linear or branched alkyl group in Ci-C _4;

o A ₃ represents a hydrogen atom or a linear or branched alkyl group in Ci-C _{4 alkyl} optionally substituted by a phenolic group

in which the arrow (->) represents the point of attachment of the phenolic group to the alkyl group of the radical A ₃ ;

ο Z represents a hydrogen atom or a phosphorus atom, Z comprising p free valence (s), p having a value of 1 or 3;

o it being understood that A ₂ and A ₃ do not both represent a hydrogen atom;

o it being understood that A! and A ₃ are not both substituted; and

A metal oxide chosen from the group consisting of the oxides of the metals of groups II, IV, V, VI, VII and VIII, and their mixtures;

the levels of zinc diacrylate derivative and peroxide being such that the ratio of the peroxide level and the rate of zinc diacrylate derivative is less than or equal to 0.09.

I- DEFINITIONS

By the expression part by weight per hundred parts by weight of elastomer (or phr), it is understood within the meaning of the present invention, the part by mass per hundred parts by mass of elastomer or rubber.

In the present, unless otherwise expressly indicated, all the rates indicated are pce; and all the percentages (%) indicated are percentages (%) by mass.

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 (i.e. limits a and b excluded) while any range of values designated by the expression from a to b signifies the range of values going from a to b (that is to say including the strict limits a and b). In the present, when we designate a range of values by the expression from a to b, we also and preferably designate the range represented by the expression between a and b.

In the present, by the expression composition based on, is meant a composition comprising the mixture and / or the reaction product of the various constituents used, some of these base constituents being capable of, or intended to react with each other, at least in part, during the various stages of manufacturing the composition, in particular during its crosslinking or vulcanization. By way of example, a composition based on an elastomeric matrix and on sulfur comprises the elastomeric matrix and the sulfur before cooking, whereas after cooking the sulfur is no longer detectable because the latter reacted with the elastomeric matrix in forming sulfur bridges (polysulfides, disulfides, mono-sulfide).

When reference is made to a majority compound, it is understood within the meaning of the present invention, that this compound is predominant among the compounds of the same type in the composition, that is to say that it is that which represents the large amount by mass among the compounds of the same type, for example more than 50%, 60%, 70%, 80%,

-490%, even 100% by weight relative to the total weight of the type of compound. Thus, for example, a majority reinforcing filler is the reinforcing filler representing the largest mass relative to the total mass of the reinforcing fillers in the composition. On the contrary, a minority compound is a compound which does not represent the largest mass fraction among the compounds of the same type.

In the context of the invention, the carbon products mentioned in the description may 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.

II- DESCRIPTION OF THE INVENTION

11-1 Diene elastomer

The rubber compositions of the tire of the invention may contain a single diene elastomer or a mixture of several diene elastomers.

By elastomer (or "rubber", the two terms being considered as synonyms) of the diene type, it is recalled here that must be understood in a known manner an (is meant one or more) elastomer derived at least in part (ie, a homopolymer or a copolymer) of diene monomers (monomers carrying two carbon-carbon double bonds, conjugated or not).

Diene elastomers can be classified into two categories, essentially unsaturated or essentially saturated. Generally understood by essentially unsaturated, a diene elastomer derived at least in part from conjugated diene monomers, having a rate 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 of alpha-olefins of the EPDM type do not enter into the preceding definition and can be qualified in particular as essentially saturated diene elastomers (rate of units d weak or very weak diene origin, always less than 15%). In the category of essentially unsaturated diene elastomers, the term “highly unsaturated diene elastomer” is understood to mean in particular a diene elastomer having a content of units of diene origin (conjugated dienes) which is greater than 50%.

These definitions being given, the term “diene elastomer capable of being used in the rubber compositions of the tire according to the invention” is understood more particularly to be:

a) any homopolymer obtained by polymerization of a conjugated diene monomer 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 vinyl aromatic compounds having from 8 to 20 carbon atoms;

c) a ternary copolymer obtained by copolymerization of ethylene, of an α-olefin having 3 to 6 carbon atoms with a non-conjugated diene monomer having of 6 to 12 carbon atoms, such as for example the elastomers obtained from ethylene, propylene with a non-conjugated diene monomer of the aforementioned type such as in particular 1,4-hexadiene, ethylidene norbornene, dicyclopentadiene;

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

Although it applies to any type of diene elastomer, a person skilled in the art of tires will understand that the present invention is preferably implemented with essentially unsaturated diene elastomers, in particular of the type (a) or (b ) above.

As conjugated dienes suitable in particular 1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-di (alkyl-C ₅₎ -1,3-butadienes such as, for example 2, 3dimethyl-1,3-butadiene, 2,3-diethyl-1,3-butadiene, 2-methyl-3-ethyl-1,3-butadiene, 2-methyl-3-isopropyl-1,3-butadiene , aryl-1,3-butadiene, 1,3-pentadiene, 2,4hexadiene. As vinyl aromatic compounds, for example, styrene, ortho-, meta-, para-methylstyrene, the commercial vinyl-toluene mixture, paratertiobutylstyrene, methoxystyrenes, chlorostyrenes, vinyl mesitylene, divinylbenzene and vinylnaphthalene are suitable.

The copolymers can contain between 99% and 20% by weight of diene units and between 1% and 80% by weight of vinyl aromatic units. The elastomers can have any microstructure which is a function of the polymerization conditions used, in particular the presence or absence of a modifying and / or randomizing agent and the quantities of modifying and / or randomizing agent used. The elastomers can be, for example, block, statistical, sequenced, microsequenced, and be prepared in dispersion or in solution; they can be coupled and / or starred or even functionalized with a coupling and / or star-forming or functionalizing agent. For coupling to carbon black, mention may, for example, be made of functional groups comprising a C-Sn bond or amine functional groups such as aminobenzophenone for example; for coupling to a reinforcing inorganic filler such as silica, mention may, for example, be made of silanol or polysiloxane functional groups having a silanol end (as described for example in FR 2 740 778, US 6 013 718 and WO 2008/141702), alkoxysilane groups (as described for example in FR 2 765 882 or US 5 977 238), carboxylic groups (as described for example in WO 01/92402 or US 6 815 473, WO 2004/096865 or US 2006/0089445 ) or also polyether groups (as described for example in EP 1 127 909, US 6 503 973, WO 2009/000750 and WO 2009/000752). As other examples of functionalized elastomers, mention may also be made of elastomers (such as SBR, BR, NR or IR) of the epoxidized type.

In summary, the diene elastomer of the composition is preferably chosen from the group of highly unsaturated diene elastomers constituted by polybutadienes (abbreviated BR), synthetic polyisoprenes (IR), natural rubber (NR), butadiene copolymers , isoprene copolymers and mixtures of these elastomers. Such copolymers are more preferably chosen from the group consisting of butadiene-styrene copolymers (SBR), isoprene-butadiene copolymers (BIR), isoprene-styrene copolymers (SIR), isoprene copolymers- butadiene-styrene (SBIR), butadiene-acrylonitrile copolymers (NBR), butadiene-styrene-acrylonitrile copolymers (NSBR) or a mixture of two or more of these compounds.

According to a particular preferred embodiment, the diene elastomer is a predominantly isoprene elastomer (that is to say of which the mass fraction of isoprene elastomer is the largest, compared to the mass fraction of

-7 other elastomers). The term isoprene elastomer is understood to mean, in known manner, an isoprene homopolymer or copolymer, in other words a diene elastomer chosen from the group consisting of natural rubber (NR) which can be plasticized or peptized, synthetic polyisoprenes ( IR), the various isoprene copolymers and the mixtures of these elastomers. Among the isoprene copolymers, mention will be made in particular of isobutene-isoprene (butyl rubber IIR), isoprene-styrene (SIR), isoprene-butadiene (BIR) or isoprene-butadiene-styrene copolymers ( SBIR). This isoprene elastomer is preferably natural rubber or a synthetic cis 1,4 polyisoprene; among these synthetic polyisoprenes, polyisoprenes are preferably used having a rate (molar%) of cis 1,4 bonds greater than 90%, more preferably still greater than 98%. Preferably according to this embodiment, the level of isoprene diene elastomer is more than 50 phr (that is to say from 50 to 100 phr), more preferably at least 60 phr (that is to say 60 to 100 phr), more preferably at least 70 phr (that is to say from 70 to 100 phr), more preferably still at least 80 phr (that is to say 80 at 100 phr) and very preferably at least 90 phr (that is to say from 90 to 100 phr). In particular according to this embodiment, the level of isoprene diene elastomer is very preferably 100 phr.

II-2 Derivative of zinc diacrylate

The composition of the tire according to the invention is based on a derivative of zinc diacrylate in the form of a zinc salt of formula (I)

in which R ^ R ₂ and R ₃ independently represent a hydrogen atom or a C1-C7 hydrocarbon group chosen from linear, branched or cyclic alkyl groups, aralkyl groups, alkylaryl groups and aryl groups, and optionally interrupted by one or more heteroatoms, R ₂ and R ₃ can together form a non-aromatic ring.

By cyclic alkyl group is meant an alkyl group comprising one or more rings.

The term “hydrocarbon group or chain interrupted by one or more heteroatoms” means a group or chain comprising one or more heteroatoms, each heteroatom being between two carbon atoms of said group or of said chain, or between one atom of carbon of said group or of said chain and another heteroatom of said group or of said chain or between two other heteroatoms of said group or of said chain. The heteroatom (s) may be a nitrogen, sulfur or oxygen atom.

Preferably, R _n R ₂ and R ₃ independently represent a hydrogen atom or a methyl group. More preferably, R ₂ and R ₃ each represent a hydrogen atom. Preferably still R! represents a methyl group. Even more advantageously, R ₂ and R ₃ each represent a hydrogen atom, and R 1 represents a methyl group.

In the rubber composition of the tire according to the invention, the amount of zinc diacrylate derivative is preferably within a range ranging from 5 to 40 phr, preferably from 7 to 35 phr, or even from 5 to 30 phr, preferably from 5 to 20 phr, preferably from 5 to 10 phr. Above a level of 40 phr, the dispersion is less good and the properties of the composition may deteriorate, while below a level of 5 phr, the effect of the zinc diacrylate derivative is less noticeable on stiffening and strengthening.

By way of example, there are commercially available zinc diacrylate derivatives such as zinc diacrylate (ZDA) "Dimalink 633" from the company Cray Valley or zinc dimethacrylate (ZDMA) "Dimalink 634" from the company Cray Valley.

ll-3 Peroxide

In addition to the elastomeric matrix and the zinc diacrylate derivative described above, the rubber composition of the tire of the invention uses a peroxide, which can be any peroxide known to those skilled in the art.

Among the peroxides, well known to those skilled in the art, it is preferable to use for the invention a peroxide chosen from the family of organic peroxides. Of

Preferably, the peroxide is an organic peroxide chosen from the group comprising or consisting of dicumyl peroxide, aryl or diaryl peroxides, diacetyl peroxide, benzoyl peroxide, dibenzoyl peroxide, ditertbutyl peroxide , tertbutylcumyl peroxide, 2,5-bis (tertbutylperoxy) -2,55 dimethylhexane, and mixtures thereof.

There are various packaged products on the market, known under their trade marks; we can cite: -the “Dicup” of the company Hercules Powder Co., the “Perkadox Y12” of the Company Noury van der Lande, the “Peroximon F40” of the company Montecatini Edison SpA, the “Trigonox” of the Company Noury van der Lande, the "Varox" from RTVanderbilt Co., or the "Luperko" from Wallace & Tiernan, Inc.

Preferably, the amount of peroxide to be used for the needs of the invention is less than or equal to 3 phr. Preferably, the amount of peroxide in the composition is within a range ranging from 0.1 to 3 phr. In fact, below an amount of 0.1 phr, the effect of the peroxide is not significant, while above 3 phr, the elongation and therefore resistance properties of the composition are reduced . More preferably, the amount of peroxide in the composition is within a range ranging from 0.2 to 2.5 phr, preferably from 0.25 to 1.8 phr.

Preferably, the ratio of the peroxide level to the level of zinc diacrylate derivative is between 0.01 and 0.09; preferably between 0.03 and 0.09 and more preferably between 0.05 and 0.08.

II-4 Phenolic derivative

The rubber composition of the tire of the invention also has the essential characteristic of containing a phenolic derivative of formula (II)

(ii) in which:

o A! represents a linear or branched C1-C4 alkyl group, optionally substituted by a carboxylate of a hydrocarbon group comprising 1 to 60 carbon atoms and optionally oxygen atoms;

o A ₂ represents a hydrogen atom or a linear or branched alkyl group in Ci-C _4;

o A ₃ represents a hydrogen atom or a linear or branched C ₁₀ -C ₄ alkyl group optionally substituted by a phenolic group

in which the arrow (->) represents the point of attachment of the phenolic group to the alkyl group of the radical A ₃ ;

ο Z represents a hydrogen atom or a phosphorus atom, Z comprising p free valence (s), p having a value of 1 or 3;

o it being understood that A ₂ and A ₃ do not both represent a hydrogen atom;

o it being understood that A! and A ₃ are not both substituted.

By alkyl group linear or branched Ci-C ₄ is meant within the meaning of the present invention, a monovalent hydrocarbon chain, linear or branched, having 1 to 4 carbon atoms. By way of example, mention may in particular be made of methyl, ethyl, propyl, isopropyl, butyl, isobutyl and tert-butyl groups.

According to the invention, the linear or branched C1-C4 alkyl group of the radicals A ₂ and A ₃ is preferably chosen from the group consisting of methyl, ethyl and tert-butyl groups.

Preferably still the A! represents a methyl group or a ter-butyl group; A ₂ and A ₃ independently of one another represent a hydrogen atom or a ter-butyl group.

For example, the compound of formula (II) can be the compound below:

o f-Bu

This compound is also known as 2,6-di-ter-butyl-4-methylphenol or BHT. This compound is commercially available, in particular under the name “Vulkanox BHT” from the company Lanxess.

Particularly advantageously, if any of the radicals A! or A ₃ is a linear or branched alkyl group in Ci-C _4, which is substituted, then Z represents a hydrogen atom.

According to a first particularly advantageous embodiment of the invention, the radical Z of the phenolic derivative of formula (II) represents a hydrogen atom.

According to this first embodiment, the phenolic derivative of formula (II) may for example be a compound of general formula (IIa)

wherein A ₃ 'represents a linear or branched alkylene group C1-C4, preferably a linear alkylene group-C _4.

By alkylene linear or branched Ci-C ₄ is meant within the meaning of the present invention, a bivalent hydrocarbon chain, linear or branched, having 1 to 4 carbon atoms. By way of example, mention may in particular be made of the groups - (CH ₂ ) -, - (CH ₂ ) ₂ -, (CH ₂ ) ₃ -, - (CH ₂ ) ₄ -, -CH ₂ -CH (CH ₃ ) -, -CH (CH ₃ ) -CH (CH ₃ ) -, - (CH ₂ ) ₂ -CH (CH ₃ ) - and -CH ₂ 10 CH (CH ₃ ) -CH ₂ -,

Preferably, in this compound of general formula (IIa), A! represents a methyl or ter-butyl group; A ₂ represents a methyl or tert-butyl group and A ₃ 'represents a methylene or ethylene. More preferably, the compound of general formula (II) is the compound below:

OH OH

This compound is also known as 2,2'-methylene-bis (4-methyl-6-tertbutylphenol) or BPH. This compound is commercially available, in particular under the name “Vulkanox BKF” from the company Lanxess.

According to the first embodiment, the phenolic derivative of formula (II) can also be, for example, a compound of general formula (Ilb)

in which Af represents a linear or branched C ₁ -C ₄ alkylene, preferably a linear C ₁ -C ₄ alkylene, and A ₄ represents a linear or branched C ₆ 5 C ₂ o alkyl group, preferably a linear or branched in C ₆ -Ci ₅ .

Preferably, in this compound of general formula (11b), Af represents a methylene or ethylene group; A ₂ and A ₃ independently of one another represent a methyl or ter-butyl group; A ₄ represents a branched C ₆ -C ₅ alkyl group. More preferably, the compound of general formula (II) is the compound below:

CH ₃ - (CH ₂ ) ₅

CH ₃ - (CH ₂ ) _s

This compound is also known under the name lsotridecyl-3- (3,5-di-tert-butyl-415 hydroxyphenyl) propionate or AO 1077. This compound is available commercially, in particular under the name "Songnox 1077 LQ" from the society

Songwon.

According to the first embodiment, the phenolic derivative of formula (II) can also be for example a compound of general formula (Ile)

in which Af represents a linear or branched C ₁ -C ₄ alkylene, preferably a linear C ₁ -C ₄ alkylene, and A ₅ represents a linear or branched C ₁ -C ₆ alkylene group, preferably a linear C 1 -C alkylene group C ₆ . More preferably, A ₅ represents a methylene or ethylene group.

Preferably, in this compound of general formula (Ile), Af represents a methylene or ethylene group; A ₂ and A ₃ independently of one another represent a methyl or ter-butyl group; A ₅ represents a linear alkyl group Ci-C _4. . More preferably, the compound of general formula (II) is the compound below:

The compound is also known as Tetrakis [methylene-3 (3 ’, 5’-di-tertbutyl-4’-hydroxyphenyl) propionate] methane. This compound is commercially available, in particular under the name "AO-1010" from the company Akrochem Corporation or "Songnox 1010" from the company Songwon.

According to a second embodiment of the invention, the radical Z of the phenolic derivative of formula (II) represents a phosphorus atom.

According to this second embodiment, the phenolic derivative of formula (II) may advantageously be a compound of general formula (lld)

-15 ^A 3

More preferably, the compound of general formula (II) is the compound below:

The compound is also known as 2,2,4-trimethyl-1,2-dihydroquinoline. This compound is commercially available, in particular under the name "IRGAFOS 168" from the company Ciba.

According to the invention, the level of the phenolic derivative of formula (II) is within a range ranging from 0.5 to 5 phr, preferably from 1 to 4 phr, or even from 0.5 to 3 phr, more preferably from 1 to 2.5 pc.

II-5 Reinforcing filler

The elastomer, the zinc diacrylate derivative, the peroxide and the antioxidant are sufficient in themselves for the invention to be carried out. However, the composition of the tire according to the invention may include a reinforcing filler known for

- 16 its capacities to reinforce a rubber composition usable for the manufacture of tires.

The reinforcing filler, when it is present, of the rubber composition of the tire according to the invention advantageously mainly comprises carbon black. The reinforcing filler may for example comprise from 50 to 100% by mass of carbon black, preferably from 55 to 90% by mass, preferably from 60 to 80% by mass. In a particularly advantageous manner, the reinforcing filler exclusively comprises carbon black. The reinforcing filler can also further comprise an inorganic reinforcing filler. Preferably, the reinforcing inorganic filler is silica.

Such a reinforcing filler typically consists of particles whose average size (by mass) is less than a micrometer, generally less than 500 nm, most often between 20 and 200 nm, in particular and more preferably between 20 and 150 nm.

The volume fraction of reinforcing filler in the rubber composition is defined as being the ratio of the volume of the reinforcing filler to the volume of all the constituents of the composition, it being understood that the volume of all the constituents is calculated in adding the volume of each of the constituents of the composition. The volume fraction of reinforcing filler in a composition is therefore defined as the ratio of the volume of the reinforcing filler to the sum of the volumes of each of the constituents of the composition, and preferably, this volume fraction is between 5% and 20%, preferably between 5% and 15%. In an equivalent preferential manner, the rate of total reinforcing filler (carbon black and optionally silica) is less than 65 phr, preferably from 5 to 60 phr, more preferably from 10 to 50 phr and very preferably, from 20 to 40 pce.

Whatever the amounts of zinc diacrylate derivative and of filler, it is advantageous for the invention for the ratio of the filler content to the content of zinc diacrylate derivative to be less than or equal to 4. Preferably, preferably , the ratio of the charge rate and the rate of zinc diacrylate derivative is within a range ranging from 0.15 to 3, preferably from 1.5 to 3. Alternatively and preferably

- 17 also, the ratio of the charge rate and the rate of zinc diacrylate derivative is in a range from 0.7 to 1.3.

The blacks which can be used in the context of the present invention can be any black conventionally used in tires or their treads (so-called pneumatic grade blacks). 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 (ASTM grades), such as, for example, the blacks N115, N134, N234, N326, N330. , N339, N347, N375, N550, N683, N772). These carbon blacks can be used in the isolated state, as commercially available, 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 WO 97/36724 or WO 99/16600). The BET specific surface area of carbon blacks is measured according to standard D6556-10 [multipoint method (minimum 5 points) - gas: nitrogen - relative pressure range Ρ / Ρ0: 0.1 to 0.3],

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 to reinforce alone, without other means than an intermediate coupling agent, a rubber composition intended for the manufacture of pneumatic tires, in other words capable of replacing, in its reinforcement function, a conventional carbon black of pneumatic grade; such a charge is generally characterized, in a known manner, by the presence of hydroxyl groups (-OH) on its surface. In other words, without a coupling agent, the inorganic filler does not make it possible to reinforce, or not sufficiently, the composition and is therefore not included in the definition of "reinforcing inorganic filler".

As reinforcing inorganic fillers, in particular mineral fillers of the siliceous type, preferably silica (SiO ₂ ), 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 surface as well as a specific surface.

CTAB both less than 450 m ² / g, preferably from 30 to 400 m ² / g, in particular

- 18 between 60 and 300 m ² / g. As highly dispersible precipitated silicas (known as HDS), mention may be made, for example, of “Ultrasil” 7000 and “Ultrasil” 7005 from Degussa, “Zeosil” 1165MP, 1135MP and 1115MP from Rhodia, and “ Hi-Sil "EZ150G from the company PPG, the silicas" Zeopol "8715, 8745 and 8755 from the company Huber, the silicas with a high specific surface as described in application WO 03/016387.

In the present description, as regards silica, the BET specific surface is determined in a known manner by gas adsorption using the Brunauer-Emmett-Teller method described in The Journal of the American Chemical Society Vol. 60, page 309, February 1938, more precisely according to French standard NF ISO 9277 of December 1996 (multi-point volumetric method (5 points) - gas: nitrogen degassing: hour at 160 ° C - relative pressure range p / in: 0.05 to 0.17). The CTAB specific surface is the external surface determined according to French standard NF T 45-007 of November 1987 (method B).

Also suitable as reinforcing inorganic fillers are mineral fillers of the aluminous type, in particular alumina (AI ₂ O ₃ ) or aluminum (oxide) hydroxides, or also reinforcing titanium oxides, for example described in US 6,610,261 and US 6,747,087.

The physical state in which the reinforcing inorganic filler is present is immaterial, whether in the form of powder, microbeads, granules, beads or any other suitable densified form. Of course, the term reinforcing inorganic filler is also understood to mean mixtures of different reinforcing inorganic fillers, in particular highly dispersible siliceous and / or aluminous fillers as described above.

Those skilled in the art will understand that, as an equivalent charge of the reinforcing inorganic charge described in this paragraph, a reinforcing charge of another nature, in particular organic, could be used, as soon as this reinforcing charge is covered with a inorganic layer such as silica, or else would have on its surface functional sites, in particular hydroxyls, requiring the use of a coupling agent to establish the connection between the filler and the elastomer. To couple the reinforcing inorganic filler to the diene elastomer,

- 19 manner well known a coupling agent (or binding agent) at least bifunctional intended to ensure a sufficient connection, chemical and / or physical, between the inorganic filler (surface of its particles) and the diene elastomer. In particular organosilanes or polyorganosiloxanes at least bifunctional are used.

Those skilled in the art can find examples of coupling agent in the following documents: WO 02/083782, WO 02/30939, WO 02/31041, WO 2007/061550, WO 2006/125532, WO 2006/125533, WO 2006/125534, US 6,849,754, WO 99/09036, WO 2006/023815, WO 2007/098080, WO 2010/072685 and WO 2008/055986.

The content of coupling agent is advantageously less than 10 phr, it being understood that it is generally desirable to use as little as possible. Typically when a reinforcing inorganic filler is present, the level of coupling agent represents from 0.5% to 15% by weight relative to the amount of inorganic filler. Its rate is preferably included in a range ranging from 0.5 to 7.5 pce. This level is easily adjusted by a person skilled in the art according to the level of inorganic filler used in the composition.

The rubber composition of the tire according to the invention may also contain, in addition to coupling agents, coupling activators, agents for recovery of inorganic charges or more generally agents for assisting in the use, capable in known manner , thanks to an improvement in the dispersion of the filler in the rubber matrix and to a lowering of the viscosity of the compositions, to improve their ability to be used in the raw state, these agents being for example hydrolysable silanes such as alkylalkoxysilanes (in particular alkyltriethoxysilanes), polyols, polyethers (for example polyethylene glycols), primary, secondary or tertiary amines (for example trialkanol-amines), hydroxylated or hydrolysable POSs, for example α, ωdihydroxy- polyorganosiloxanes (in particular α, ω-dihydroxy-polydimethylsiloxanes), fatty acids such as for example stearic acid.

II-6 Metal oxide

The composition of the tire according to the invention also comprises a metal oxide.

The metal oxide can be chosen from the group consisting of the oxides of the metals of group II, IV, V, VI, Vil and VIII, and their mixtures. Preferably, the metal oxide is chosen from the group consisting of oxides of zinc, magnesium, cobalt, nickel and their mixtures. More preferably, the metal oxide is a zinc oxide.

The metal oxide content of the composition of the tire according to the invention is advantageously greater than 5 phr. Preferably, this rate is included in a range ranging from 5 to 20 phr, preferably from 7 to 15 phr.

By way of example of commercially available metal oxides, mention may be made of industrial grade zinc or magnesium oxides from the company Umicore.

II-7 Vulcanization system

The composition of the tire according to the invention does not require a vulcanization system, which is one of its advantages since this makes it possible to simplify the formula, and the preparation of the composition. If, however, a vulcanization system is present in the composition, it is preferably present in small quantities.

The actual vulcanization system is usually based on sulfur (or a sulfur-donating agent) and a primary vulcanization accelerator. To this basic vulcanization system are 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 zinc oxide , stearic acid or equivalent compounds, guanidine derivatives (in particular diphenylguanidine).

Molecular sulfur (or equivalent molecular sulfur donor agents), when used, is preferably less than 0.5 phr,

Thus, very preferably, the composition does not contain molecular sulfur or of sulfur-donating agent as vulcanizing agent or contains less than 0.5 phr, preferably less than 0.3 phr, preferably even less than 0.1 pc. More preferably, the composition of the tire according to

The invention does not contain molecular sulfur or a sulfur donor agent as a vulcanizing agent.

The vulcanization system of the composition according to the invention may also comprise one or more additional accelerators, for example the compounds of the thiuram family, zinc dithiocarbamate derivatives, sulfenamides, guanidines or thiophosphates. It is possible in particular to use any compound capable of acting as an accelerator for vulcanization of diene elastomers in the presence of sulfur, in particular accelerators of the thiazole type and their derivatives, accelerators of the thiuram type, zinc dithiocarbamates. These accelerators are more preferably chosen from the group consisting of 2-mercaptobenzothiazyl disulfide (abbreviated MBTS), N-cyclohexyl-2benzothiazyle sulfenamide (abbreviated CBS), N, N-dicyclohexyl-2-benzothiazyle sulfenamide (abbreviated DCBS) , N-tert-butyl-2-benzothiazyle sulfenamide (abbreviated TBBS), N-tert-butyl-2-benzothiazyle sulfenimide (abbreviated TBSI), zinc dibenzyldithiocarbamate (abbreviated ZBEC) and mixtures of these compounds. Preferably, a primary accelerator of the sulfenamide type is used.

If an accelerator is used, it is used at rates such as those practiced by those skilled in the art of vulcanized compositions for tires. However, the composition of the tire according to the invention is preferably devoid of any vulcanization accelerator.

I-8 Other possible additives

The rubber compositions of the tire according to the invention optionally also include all or part of the usual additives usually used in elastomer compositions for tires, such as, for example, pigments, protective agents such as anti-ozone waxes, anti-ozonants chemicals, plasticizing agents (such as a solid hydrocarbon resin (or plasticizing resin), an extension oil (or plasticizing oil), or a mixture of the two), anti-fatigue agents, reinforcing resins, acceptors (e.g. phenol novolak) or methylene donors (e.g. HMT or H3M).

-2211-9 Tires

The present invention also relates to a finished or semi-finished rubber article, as well as a tire, comprising a composition in accordance with the present invention.

The invention relates particularly to tires intended to equip motor vehicles of the touring type, SUV (Sport Utility Vehicles), or two wheels (in particular motorcycles), or airplanes, or even industrial vehicles chosen from vans, “Heavy vehicles”. - i.e. metro, bus, road transport equipment (trucks, tractors, trailers), off-road vehicles such as agricultural or civil engineering equipment -, and others.

It is possible to define within the tire three types of zones:

• The radially outer zone and in contact with the ambient air, this zone essentially consisting of the tread and the external side of the tire. An external sidewall is an elastomeric layer disposed outside the carcass reinforcement relative to the internal cavity of the tire, between the crown and the bead so as to completely or partially cover the area of the carcass reinforcement extending from the top to the bead.

• The radially inner zone and in contact with the inflation gas, this zone generally being constituted by the layer which is impermeable to the inflation gases, sometimes called the inner waterproof layer or inner rubber.

• The internal zone of the tire, that is to say that between the external and internal zones. This zone includes layers or plies which are here called internal layers of the tire. These are for example carcass plies, tread underlays, plies of tire belts or any other layer which is not in contact with the ambient air or the inflation gas of the tire.

The composition defined in this description is particularly well suited to the internal layers of tires.

Also, in the tire according to the present invention, the composition can be present in at least one internal layer of the tire. According to the invention, the internal layer can be chosen from the group consisting of carcass plies,

-23 crown tablecloths, rod stuffing, crown feet, crown feet, decoupling layers, edge rubbers, tread underlayment and combinations of these internal layers. Preferably, the internal layer is chosen from the group consisting of carcass plies, crown plies, rod stuffing, crown feet, decoupling layers and combinations of these internal layers.

The invention relates to the tires and semi-finished products for tires described above, to rubber articles, both in the raw state (that is to say, before baking) and in the cooked state (that is to say , after crosslinking or vulcanization).

11-10 Preparation of rubber compositions

The compositions are produced in suitable mixers, using two successive preparation phases well known to those skilled in the art: a first working phase or thermo-mechanical kneading (sometimes referred to as a nonproductive phase) at high temperature, up to a maximum temperature between 110 ° C and 190 ° C, preferably between 130 ° C and 180 ° C, followed by a second mechanical working phase (sometimes referred to as the productive phase) at a lower temperature, typically below 110 ° C , for example between 60 ° C and 100 ° C, finishing phase during which is incorporated the crosslinking system and in particular the peroxide of the compositions according to the invention; such phases have been described for example in applications EP-A-0501227, EP-A-0735088, EP-A-0810258, WO00 / 05300 or WO00 / 05301.

The first (non-productive) phase is preferably carried out in several thermomechanical stages. During a first step, elastomers and reinforcing fillers (and optionally coupling agents and / or other ingredients) are introduced into a suitable mixer such as a conventional internal mixer, at a temperature between 20 ° C and 100 ° C and preferably between 25 ° C and 100 ° C. After a few minutes, preferably from 0.5 to 2 min and a rise in temperature to 90 ° C to 100 ° C, the other ingredients (that is to say, those which remain if all have not been put at the start) are added all at once or in parts, with the exception of the crosslinking system and in particular of the peroxide during mixing ranging from 20 seconds to a few minutes. The total duration of the mixing, in this phase no 3060012

-24productive, is preferably between 2 and 10 minutes at a temperature less than or equal to 180 ° C, and preferably less than or equal to 170 ° C.

After the mixture thus obtained has cooled, the crosslinking system, and in particular the peroxide, is then incorporated at low temperature (typically less than 100 ° C.), generally in an external mixer such as a cylinder mixer; the whole is then mixed (productive phase) for a few minutes, for example between 5 and 15 min.

The final composition thus obtained is then calendered, for example in the form of a sheet or a plate, in particular for characterization in the laboratory, or else extruded, to form for example a rubber profile used for the manufacture of semi-finished products. finished in order to obtain products known as “internal layers” such as carcass ply, crown plies (or tire belt), bead stuffing. These products can then be used for the manufacture of tires, according to techniques known to those skilled in the art.

The cooking is carried out in a known manner at a temperature generally between 130 ° C and 200 ° C, under pressure, for a sufficient time which can vary for example between 5 and 90 min depending in particular on the cooking temperature, the system of vulcanization adopted, of the vulcanization kinetics of the composition considered or of the size of the tire.

III- EXAMPLES

111-1 Measurements and tests used

Dynamic properties (after baking): Tensile test

These tensile tests make it possible to determine the elasticity stresses and the breaking properties. Unless otherwise indicated, they are carried out in accordance with French standard NF T 46-002 of September 1988. Processing of the tensile recordings also makes it possible to plot the module curve as a function of the elongation. The module used here being the nominal (or apparent) secant module measured at first elongation, calculated by reducing to the initial section of the test piece. The nominal secant module (or apparent stresses, in MPa) is measured at first elongation at 23 ° C at 100% elongation denoted M100.

-25The rupture elongation (AR%) and rupture stress (CR) tests are based on the NF ISO 37 standard of December 2005 on a H2 type dumbbell test piece and are measured at a tensile speed of 500 mm / min. The elongation at break is expressed in% of elongation. The breaking stress is expressed in MPa.

The force and the tear deformation are measured on a test specimen stretched at 500 mm / min to cause rupture of the test specimen. The tensile test piece consists of a rubber plate of parallelepiped shape, for example of thickness between 1 and 2 mm, length between 130 and 170 mm and width between 10 and 15 mm, the two lateral edges being each covered lengthwise with a cylindrical rubber bead (diameter 5 mm) allowing anchoring in the jaws of the traction machine. 3 very fine cuts of length between 15 and 20 mm are made using a razor blade, half-width and aligned lengthwise of the test piece, one at each end and one in the center of the latter, before starting the test. The force (N / mm) to be exerted to obtain the rupture is determined and the elongation at break and the stress at break are measured. The product of the tear strength and the tear deformation (elongation at break) gives the tear energy which is a descriptor of the cohesion of the material to resist cracking.

All these traction measurements are carried out under normal temperature (23 ± 2 ° C) and hygrometry (50 ± 5% relative humidity) conditions, according to French standard NFT 40-101 (December 1979).

III-2 Preparation of the compositions

In the following examples, the rubber compositions were produced as described above.

III-3 Tests of rubber compositions

Three compositions (denoted below B, D and F) in accordance with the invention in that they comprise an antioxidant which is a phenolic derivative of formula (II), and three compositions (denoted below C, E and G ) not in accordance with the invention in that they comprise an antioxidant which is not a phenolic derivative of formula (II) have been

-26compared to a Control A composition which does not include an antioxidant. Their formulations (in pce) have been summarized in Table I below.

First, the M100 stiffnesses of the compositions were measured. In a second step, the cohesion properties of resistance to crack propagation were measured for the compositions having little or no degradation of the rigidity compared to Control A. The results are presented in Tables II and III below .

The results of stiffness (M100), elongation at break (AR%), stress at break, tear strength, tear deformation and tear energy are presented in “base 100” compared to the Control A composition. The higher the value, the better the result.

Table I

Witness AT B VS D E F G NR (1) 100 100 100 100 100 100 100 N234 (2) 50 50 50 50 50 50 50 ZnO (3) 9 9 9 9 9 9 9 ZDMA (4) 20 20 20 20 20 20 20 Dicup (5) 1.5 1.5 1.5 1.5 1.5 1.5 1.5 BHT (6) - 2 - - - - - TMQ (7) - - 2 - - - - IRGAFOS 168 (8) - - - 2 - - - DLTDP (9) - - - - 2 - - BPH (10) - - - - - 2 - 6PPD (11) - - - - - - 2

(1) Natural rubber (2) Carbon black N234 (name according to ASTM D-1765) (3) Zinc oxide (industrial grade - Umicore company) (4) Zinc dimethacrylate (“Dimalink 634” from Cray company Valley) (5) Dicumyl peroxide (“Dicup” from the company Hercules) (6) 2,6-di-ter-butyl-4-methylphenol (“Vulkanox BHT” from the company Lanxess) (7) 2,2, 4-trimethyl-1,2-dihydroquinoline ("TMQ" from the company Nocil) (8) Tris (2,4-di-tert-butylphenyl) phosphite ("Irgafos 168" from the company Ciba) (9) dilaurylthidipropionate (" BNX DL TDP ”from Mayzo) (10) 2,2'-methylene-bis (4-methyl-6-tert-butylphenol) (“ Vulkanox BPH ”from Lanxess) (11) N-1,3- dimethylbutyl-N-phenylparaphenylenediamine ("Santoflex 6-PPD" from the company Flexsys)

-27Table II

Witness AT B vs D E F G M100 100 100 82 102 100 99 47

Table III

Witness AT B D E F Breaking stress 100 110 112 107 114 AR% 100 101 101 97 103 Tear strength 100 135 140 83 126 Tear deformation 100 112 78 80 106 Energide of tearable 100 151 109 66 134

These results show that the only compositions in accordance with the present invention comprising a phenolic derivative of formula (II) make it possible to improve both the cohesion and tear resistance properties, without penalizing the rigidity of the composition.

Claims (14)

1. A tire comprising a rubber composition based on at least: a diene elastomer, 5 - a peroxide, a derivative of zinc diacrylate in the form of a zinc salt of formula (I) r ₂ oor ₂ in which FL, R ₂ and R ₃ independently represent one another a hydrogen atom or a C1-C7 hydrocarbon group chosen from 10 linear, branched or cyclic alkyl groups, aralkyl groups, alkylaryl groups and aryl groups, and possibly interrupted by one or more heteroatoms, R ₂ and R _{3 being} able to form together a non-aromatic ring, a phenolic derivative of formula (II ) 15 (II) in which: o A! represents a linear or branched C1-C4 alkyl group, optionally substituted by a carboxylate of a hydrocarbon group comprising 1 to 60 carbon atoms and optionally 20 oxygen atoms; o A ₂ represents a hydrogen atom or a linear or branched alkyl group in Ci-C _4; o A ₃ represents a hydrogen atom or a linear or branched alkyl group in Ci-C _{4 alkyl} optionally substituted with a phenolic group in which the arrow (->) represents the point of attachment of the phenolic moiety of the alkyl radical A ₃ ; ο Z represents a hydrogen atom or a phosphorus atom, Z comprising p free valence (s), p having a value of 1 or 3; o it being understood that A ₂ and A ₃ do not both represent a hydrogen atom; o it being understood that A! and A ₃ are not both substituted; and a metal oxide chosen from the group consisting of the oxides of the metals of groups II, IV, V, VI, VII and VIII, and their mixtures; the levels of zinc diacrylate derivative and peroxide being such that the mass ratio of the peroxide level and the rate of zinc diacrylate derivative is less than or equal to 0.09. 2. A tire according to claim 1, in which F ^, R ₂ and R ₃ independently represent a hydrogen atom or a methyl group. 3. Tire according to claim 1 or 2, wherein R ₂ and R ₃ each represent a hydrogen atom. 4. A tire according to any one of claims 1 to 3, in which R! represents a methyl group. 5. A tire according to any one of claims 1 to 4, in which the amount of zinc diacrylate derivative in the composition is within a range from 5 to 40, parts by weight per hundred parts by weight of elastomer, pce, preferably from 7 to 35 pce. 6. A tire according to any one of claims 1 to 5, in which the linear or branched C1-C4 alkyl group of the radicals A ^ A ₂ and A ₃ is chosen from the group consisting of methyl, ethyl and ter- butyl. -307. A tire according to any one of claims 1 to 6, in which A! represents a methyl group or a ter-butyl group; A ₂ and A ₃ independently of one another represent a hydrogen atom or a ter-butyl group. 8. A tire according to any one of claims 1 to 7, in which Z represents a hydrogen atom. 9. A tire according to any one of claims 1 to 5, and 8, in which the phenolic derivative of formula (II) is a compound of general formula (IIa) (Ha) in which A ₃ 'represents a linear alkylene group or branched into C1-C4. 10. A tire according to claim 9, in which A! represents a methyl or ter-butyl group; A ₂ represents a methyl or tert-butyl group and A ₃ 'represents a methylene or ethylene. 20 11. A tire according to any one of claims 1 to 5 and 8, in which the phenolic derivative of formula (II) is a compound of general formula (llb) (Hb) -31 in which fif represents a linear or branched C1-C4 alkylene, and A ₄ represents a linear or branched C ₆ -C ₂₀ alkyl group. 12. The tire of claim 11, wherein A / represents a methylene or ethylene group; A ₂ and A ₃ independently of one another represent a methyl or ter-butyl group; A ₄ represents a branched C ₆ -C ₅ alkyl group. 13. A tire according to any one of claims 1 to 5 and 8, in which the phenolic derivative of formula (II) is a compound of general formula (Ile) in which A / represents a linear or branched CiC ₄ alkylene, and a ₅ represents a linear alkylene group or branched Ci-C _6. 14. A tire according to claim 13, in which A / represents a methylene or ethylene group; A ₂ and A ₃ independently of one another represent a methyl or ter-butyl group; A ₅ represents a linear alkyl group Ci-C _4. 15. Tire according to any one of claims 1 to 7, in which Z represents a phosphorus atom. 16. A tire according to claim 15, in which the phenolic derivative of formula (II) is a compound of general formula (IId) 17. A tire according to any one of claims 1 to 16, in which the level of the phenolic derivative of formula (II) is within a range ranging from 0.5 to 5 5 pce, preferably from 1 to 4 pce. 18. Tire according to any one of claims 1 to 17, in which the peroxide in the composition is an organic peroxide. 19. The tire according to claim 18, in which the organic peroxide is chosen from the group consisting of dicumyl peroxide, aryl or diaryl peroxides, diacetyl peroxide, benzoyl peroxide, dibenzoyl peroxide, ditertbutyl peroxide, tertbutylcumyl peroxide, 2,5-bis (tertbutylperoxy) -2,5dimethylhexane, and mixtures thereof. 20. A tire according to any one of claims 1 to 19, in which the amount of peroxide in the composition is less than or equal to 3 phr. 21. A tire according to any one of claims 1 to 20, in which the 20 amount of peroxide in the composition is in a range from 0.1 to 3 phr, preferably from 0.2 to 2.5 phr. 22. A tire according to any one of claims 1 to 21, in which the ratio of the peroxide level to the level of zinc diacrylate derivative is understood Between 0.01 and 0.09; preferably between 0.03 and 0.09 and more preferably between 0.05 and 0.08. 23. A tire according to any one of claims 1 to 22, in which the diene elastomer is chosen from the group consisting of polybutadienes, -33 synthetic polyisoprenes, natural rubber, butadiene copolymers, isoprene copolymers and mixtures of these elastomers. 24. A tire according to claim 23, in which the diene elastomer mainly comprises at least one isoprene elastomer. 25. A tire according to claim 24, in which the isoprene elastomer is chosen from the group consisting of natural rubber, synthetic polyisoprenes and mixtures of these elastomers. 26. A tire according to any one of claims 1 to 25, said composition not comprising a reinforcing filler or comprising less than 65 phr, the reinforcing filler mainly consisting of carbon black. 27. A tire according to claim 26, in which the rate of reinforcing filler is in a range from 5 to 60 phr, preferably from 10 to 50 phr. 28. A tire according to claim 26 or 27, in which the reinforcing filler further comprises silica. 29. A tire according to any one of claims 26 to 28, in which the ratio of the loading rate and the rate of zinc diacrylate derivative is less than or equal to 4. 30. A tire according to any one of claims 26 to 29, wherein the ratio of the loading rate and the rate of zinc diacrylate derivative is within a range from 0.15 to 3; preferably 1.5 to 3. 31. The rubber composition according to any one of claims 1 to 30, wherein the metal oxide is a zinc oxide. 32. The rubber composition according to claim 31, wherein the level of metal oxide is greater than 5 phr. 33. The rubber composition according to claim 31 or 32, wherein the level of metal oxide is in a range from 5 to 20 phr, preferably from 7 to 15 phr. -3434. A tire according to any one of claims 1 to 33, in which the composition does not contain or contains less than 0.5 phr of molecular sulfur or of sulfur-donating agent as vulcanizing agent. 35. A tire according to any one of claims 1 to 34, in which the composition does not contain molecular sulfur or of sulfur-donating agent as vulcanizing agent or contains less than 0.3 phr and preferably less than 0.1 pc. 36. Tire according to one of the preceding claims, in which the composition defined in any one of claims 1 to 35 is present in at least one internal layer of said tire. 15 37. A tire according to claim 36, in which the internal layer is chosen from the group consisting of carcass plies, crown plies, bead-stuffing, crown feet, decoupling layers, border erasers, underlayment. -tread layer and combinations of these internal layers.