Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C1/00—Tyres characterised by the chemical composition or the physical arrangement or mixture of the composition
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/36—Sulfur-, selenium-, or tellurium-containing compounds
  • C08K5/45—Heterocyclic compounds having sulfur in the ring
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/18—Oxygen-containing compounds, e.g. metal carbonyls
  • C08K3/20—Oxides; Hydroxides
  • C08K3/22—Oxides; Hydroxides of metals
  • C08K2003/2296—Oxides; Hydroxides of metals of zinc
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/18—Oxygen-containing compounds, e.g. metal carbonyls
  • C08K3/20—Oxides; Hydroxides
  • C08K3/22—Oxides; Hydroxides of metals
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/34—Silicon-containing compounds
  • C08K3/36—Silica
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/0008—Organic ingredients according to more than one of the "one dot" groups of C08K5/01 - C08K5/59
  • C08K5/0025—Crosslinking or vulcanising agents; including accelerators
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/36—Sulfur-, selenium-, or tellurium-containing compounds
  • C08K5/39—Thiocarbamic acids; Derivatives thereof, e.g. dithiocarbamates
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/36—Sulfur-, selenium-, or tellurium-containing compounds
  • C08K5/45—Heterocyclic compounds having sulfur in the ring
  • C08K5/46—Heterocyclic compounds having sulfur in the ring with oxygen or nitrogen in the ring
  • C08K5/47—Thiazoles
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/54—Silicon-containing compounds
  • C08K5/548—Silicon-containing compounds containing sulfur

Definitions

• the present invention relates to the field of crosslinking of unsaturated polymers, in particular elastomers, and more particularly diene elastomers.
• the present invention particularly relates to compositions comprising unsaturated polymers and polysulfide compounds which may be crosslinking agents.
• Unsaturated polymers are part of the constitution of many objects of everyday life, such as tires, shoe soles, seals, glues, foam articles, profiles for the automobile, etc. These are macromolecules having carbon-carbon double bonds, also called unsaturations, in their main chain and / or in their side chain (s).
• the principle of vulcanization also called sulfur crosslinking, lies in the creation of sulfur bridges between different chains of macromolecules by reaction on the double bonds of these chains of a vulcanizing agent.
• the vulcanizing agent also called sulfur donor, is a compound that is capable of releasing sulfur by heating to the vulcanization temperature.
• the most known and most commonly used vulcanizing agent is elemental sulfur.
• compositions comprising at least one unsaturated polymer, in particular an elastomer, in particular a diene elastomer, having improved properties, especially breaking elongation properties, with high mechanical stresses by compared to compositions obtained so far by sulfur crosslinking. It may also be interesting, moreover, that these compositions have improved elongation properties at low mechanical stresses.
• the objective of the present invention is to meet this need.
• the sulfur crosslinking is generally carried out using a vulcanization system comprising elemental sulfur and a vulcanization accelerator, and optionally a complementary vulcanization accelerator.
• This system while it makes it possible to modify the mechanical properties of compositions comprising unsaturated polymers, in particular elastomers, in particular diene elastomers, is intended to disadvantage of leading to limited resistance vulcanisais obtained due to the thermal aging of the latter ("thermal aging").
• thermal aging the vulcanizates undergo many stresses, including thermal stresses. These thermal stresses are the effect of overcuring, which when the temperature of the vulcanizate reaches a value close to the vulcanization temperature, causes a phenomenon of reversion.
• Reversion is a rupture of the network of crosslinking by destruction or shortening of the bridges of sulfur created during vulcanization; that is to say a reduction of polysulfide bridges in favor of monosulphide or disulfide bridges. This rupture of the network adversely modifies the mechanical properties of the vulcanisai.
• Another preferred complementary objective of the present invention is to provide a composition comprising an unsaturated polymer, in particular an elastomer, in particular a diene elastomer, which exhibits no reversion phenomenon or a limited reversion phenomenon.
• the invention relates to a composition based on at least one unsaturated polymer and a polysulfurized compound of general formula (I).
• a and B together form a covalent bond or A represents a hydrogen atom and B represents a hydrogen atom or a -SH group;
• n is a number in a range from 1 to 3;
• p is a number greater than or equal to 1;
• R 1 and R 2 represent, independently of one another, identical or different divalent hydrocarbon groups containing from 1 to 18 carbon atoms, optionally interrupted by a heteroatom.
• the Applicant has also found that the use of a polysulfide compound of formula (I) in combination with at least one vulcanization accelerator and at least one complementary vulcanization accelerator made it possible to improve the breaking elongations. at low temperatures.
• the invention relates to an article comprising at least one composition as definie above.
• this article is a tire.
• the invention relates to a process for the manufacture of a composition
• a composition comprising at least one unsaturated polymer, at least one filler and at least one polysulfurized compound of general formula (I)
• a and B together form a covalent bond or A represents a hydrogen atom and B represents a hydrogen atom or a -SH group;
• n is a number in a range from 1 to 3;
• p is a number greater than or equal to 1;
• R 1 and R 2 represent, independently of one another, identical or different divalent hydrocarbon groups containing from 1 to 18 carbon atoms, optionally interrupted by a heteroatom;
• said method comprising at least the following steps:
• step (a) the filler is mixed with the unsaturated polymer in a mixer; b) the mixture of step (a) is mechanically kneaded one or more times until a maximum temperature of less than or equal to 200 ° C. is reached; ,
• step (b) cooling the mixture obtained at the end of step (b) to a temperature below 100 ° C; d) is incorporated in the mixture obtained at the end of step (c) said polysulfurized compound of general formula (I) and,
• step (d) kneading the mixture obtained at the end of step (d) to a temperature below 120 ° C.
• the invention relates to the use of at least one polysulfide compound of general formula (I) as a crosslinking agent for unsaturated polymers.
• a and B together form a covalent bond or A represents a hydrogen atom and B represents a hydrogen atom or a -SH group;
• n is a number in a range from 1 to 3;
• p is a number greater than or equal to 1;
• R 1 and R 2 represent, independently of one another, identical or different divalent hydrocarbon groups containing from 1 to 18 carbon atoms, optionally interrupted by a heteroatom.
• the invention relates to a process for crosslinking unsaturated polymers, said process comprising at least the following steps:
• a and B together form a covalent bond or A represents a hydrogen atom and B represents a hydrogen atom or a -SH group;
• n is a number in a range from 1 to 3;
• p is a number greater than or equal to 1;
• R 1 and R 2 represent, independently of one another, identical or different divalent hydrocarbon groups containing from 1 to 18 carbon atoms, optionally interrupted by a heteroatom; and heating the mixture obtained above to a temperature greater than or equal to 130 ° C, preferably between 130 ° C and 200 ° C.
• the invention relates to a crosslinking system comprising at least one vulcanization accelerator and at least one polysulfurized compound of general formula (I)
• a and B together form a covalent bond or A represents a hydrogen atom and B represents a hydrogen atom or a -SH group;
• n is a number in a range from 1 to 3;
• p is a number greater than or equal to 1;
• R 1 and R 2 represent, independently of one another, identical or different divalent hydrocarbon groups containing from 1 to 18 carbon atoms, optionally interrupted by a heteroatom.
• the measurements are carried out at 150 ° C. or at 190 ° C. with an oscillating chamber rheometer, according to the standard DIN53529 - part 3 (June 1983).
• the evolution of the rheometric torque as a function of time describes the evolution of the stiffening of the composition following the crosslinking reaction.
• the measurements are processed according to DIN53529 - Part 2 (March 1983): the minimum and maximum torques, measured in dN.m (deciNewton.meter) are respectively named C min and C max , the distance noted ACouple ( in dN.min) between C max and C min which makes it possible to assess the crosslinking efficiency.
• the conversion rate constant expressed in min 1 of order 1, calculated between 30% and 80% of conversion is also measured which makes it possible to assess the kinetics of crosslinking.
• the reversion rate expressed in% is calculated according to the equation below:
• the percentage of reversion is calculated from the vulcanization isotherm measured by the method DIN-53529.
• the value of C max corresponds to the maximum torque in dN.m reached during the ascending phase of vulcanization. When there is a phenomenon of reversion, then the measured torque decreases with time.
• the percentage of reversion that appears 5 minutes after reaching the C max torque has been calculated: it therefore corresponds to the rheometric torque measured according to the vulcanization isotherm, 5 minutes after the C max has been reached.
• the measured properties are the modules of the compositions, as determined in tensile tests. These tests make it possible to determine the elastic stress and the properties at break. They are carried out in accordance with the French standard NF T 46-002 of September 1988.
• the elongations at break (in%) are measured in second elongation (i.e. after an accommodation cycle).
• the measurements of elongation at break (denoted AR) are carried out under the normal conditions of temperature (23 ⁇ 2 ° C.) and hygrometry (50 ⁇ 5% relative humidity), according to the French standard NF T 40- 101 (December 1979), and also at 100 ° C.
• the nominal secant moduli (or apparent stresses, in MPa, related to deformation, without unit) at 10%, 100% or 300% elongation (denoted MA10, MA100 and MA300) and the true stresses at break (in MPa) can also be measured.
• any range of values designated by the expression "between a and b" represents the range of values from more than “a” to less than “b” (i.e. a and b excluded) while any range of values referred to as “a to b” means the range of values from “a” to "b” (ie including strict bounds a and b).
• the term "phr” (usually “phr” in English) the part by weight of a constituent per hundred parts by weight of the elastomer or elastomers, that is to say the total weight of or elastomers.
• the carbon-containing products mentioned in the description may be of fossil origin or biobased. In the latter case, they can be, partially or totally, derived from biomass or obtained from renewable raw materials derived from biomass. These include polymers, plasticizers, fillers, etc.
• a first subject of the invention relates to a composition based on at least one unsaturated polymer and at least one polysulfurized compound of general formula (I)
• a and B together form a covalent bond or A represents a hydrogen atom and B represents a hydrogen atom or a -SH group;
• n is a number in a range from 1 to 3;
• p is a number greater than or equal to 1;
• R 1 and R 2 represent, independently of one another, identical or different divalent hydrocarbon groups containing from 1 to 18 carbon atoms, optionally interrupted by a heteroatom.
• composition based on is meant a composition comprising the mixture and / or the reaction product in situ of the various basic constituents used, some of these constituents being able to react and / or being intended to react. between them, at least partially, during the various phases of manufacture of the composition, or during the subsequent firing, modifying the composition as it was initially prepared.
• the compositions as implemented for the invention may be different in the uncrosslinked state and in the crosslinked state.
• the composition of the invention comprises at least one unsaturated polymer, that is to say a single unsaturated polymer or a mixture of unsaturated polymers.
• the unsaturated polymer is an elastomer.
• the unsaturated polymer is a diene elastomer.
• elastomer or "rubber”, the two terms being considered as synonymous
• the two terms being considered as synonymous
• elastomeric origin at least in part ( ie, a homopolymer or copolymer) of diene monomers (monomers bearing two carbon-carbon double bonds, conjugated or otherwise).
• the diene elastomers can be classified in two categories: "essentially unsaturated” or "essentially saturated”.
• essentially unsaturated is generally understood to mean 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 weight). moles).
• conjugated diene monomers having a proportion of units or units of diene origin (conjugated dienes) which is greater than 15% (% by weight). moles).
• highly unsaturated diene elastomer is particularly understood to mean a diene elastomer having a content of units of diene origin (conjugated dienes) which is greater than 50% (mol%).
• essentially saturated is generally understood to mean 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 less than 15% (% by weight). moles), such as butyl rubbers or copolymers of dienes and alpha-olefins EPDM type.
• iene elastomer can be understood more particularly to be used in the compositions according to the invention:
• the invention applies to any type of diene elastomer.
• the composition is intended for the preparation of pneumatic tires, the person skilled in the art will understand that the present invention is preferably carried out with essentially unsaturated diene elastomers, in particular of the type (a) or (b) above.
• 1,3-butadiene or isoprene
• 2,3-di (C 1 -C 5) alkyl-1,3-butadienes such as, for example, 2,3-dimethyl-1,3-butadiene, 2,3-diethyl 1,3-butadiene, 2-methyl-3-ethyl-
• Suitable vinylaromatic compounds are, for example, styrene, ortho-, meta-, para-methylstyrene, the commercial mixture "vinyl-toluene", para-tert-butylstyrene, methoxystyrenes, chlorostyrenes, vinylmesitylene, divinylbenzene, vinylnaphthalene.
• the copolymers may contain between 99% and 20% by weight of diene units and between 1% and 80% by weight of vinylaromatic units.
• the elastomers may 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 amounts 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 may be coupled and / or starred or functionalized with a coupling agent and / or starring or functionalization.
• 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).
• elastomers such as SBR, BR, NR or IR
• functionalized elastomers may be used in a blend with each other or with unfunctionalized elastomers.
• a functionalized silanol or polysiloxane elastomer having a silanol end, in admixture with a coupled and / or stanned tin elastomer may be used, the latter representing a rate of from 5 to 50 %, for example from 25 to 50%.
• styrene content of between 5% and 60% by weight and more particularly between 20% and 50%, a content (mol%) in -1,2 bonds of the butadiene part of between 4% and 75%, a content (mol%) of trans-1 bonds, 4 between 10% and 80%, butadiene-isoprene copolymers and especially those having an isoprene content of between 5% and 90% by weight and a Tg of -40 ° C to -80 ° C, the isoprene-copolymers styrene and in particular those having a styrene content of between 5% and 50% by weight and a Tg of between -5 ° C and -60 ° C.
• butadiene-styrene-isoprene copolymers are especially suitable those having a styrene content of between 5% and 50% by weight and more particularly of between 10% and 40%, an isoprene content of between 15% and 60%.
• the diene elastomer of the composition of the invention is chosen from the group of highly unsaturated diene elastomers consisting of polybutadienes (abbreviated to BR), synthetic polyisoprenes (IR) and natural rubber (NR). , butadiene copolymers, isoprene copolymers and mixtures of these diene elastomers.
• BR polybutadienes
• IR synthetic polyisoprenes
• NR natural rubber
• Such copolymers are more preferably selected from the group consisting of butadiene-styrene copolymers (SBR), isoprene-butadiene copolymers (BIR), isoprene-styrene copolymers (SIR), isoprene-copolymers of butadiene-styrene (SBIR), butadiene-acrylonitrile copolymers (NBR), butadiene-styrene-acrylonitrile copolymers (NSBR) or a mixture of two or more of these compounds.
• SBR butadiene-styrene copolymers
• BIR isoprene-butadiene copolymers
• SIR isoprene-styrene copolymers
• NBR butadiene-acrylonitrile copolymers
• NSBR butadiene-styrene-acrylonitrile copolymers
• an SBR elastomer In the case of an SBR elastomer (ESBR or SSBR), an SBR having an average styrene content, for example between 20% and 35% by weight, or a high styrene content, for example 35 to 35% by weight, is used in particular. 45%, a vinyl ring content of the butadiene part of between 15% and 70%, a content (mol%) of trans 1,4 bonds of between 15% and 75% and a Tg of between -10 ° C. and 55 ° C; such an SBR can be advantageously used in admixture with a BR preferably having more than 90% (mol%) of 1,4 cis bonds. More preferably still, the diene elastomer is natural rubber or a synthetic polyisoprene.
• the diene elastomers may be used in blending (mixing) with each other.
• the compositions in accordance with the invention may preferably contain a single diene elastomer, functionalized or not, or a mixture of several diene elastomers, functionalized or not, this or these diene elastomers may be used in combination with any type of elastomer synthetic other than diene, or with polymers other than elastomers, for example thermoplastic polymers.
• the level of diene elastomer in the composition is more than 50 phr (that is to say 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 (i.e. from 80 to 100 phr) and very preferably at least 90 phr (that is to say from 90 to 100 phr).
• the level of diene elastomer is very preferably 100 phr.
• composition of the invention comprises at least one polysulfurized compound of general formula (I)
• a and B together form a covalent bond or A represents a hydrogen atom and B represents a hydrogen atom or a -SH group;
• n is a number in a range from 1 to 3;
• p is a number greater than or equal to 1;
• R 1 and R 2 represent, independently of one another, identical or different divalent hydrocarbon groups containing from 1 to 18 carbon atoms, optionally interrupted by a heteroatom.
• the polysulfide compound of general formula (I) may have the function of cross-linking together the unsaturated polymer chains, in particular the chains of the elastomers, in particular the chains of the diene elastomers.
• the polysulfurized compound of general formula (I) may be a crosslinking agent. It can advantageously replace the elemental sulfur usually used in crosslinking.
• the composition of the invention does not include elemental sulfur or comprises elemental sulfur at a level of less than 1 phr, preferably less than or equal to 0.5 phr.
• the polysulfide compound of formula (I) may also be used in addition to a crosslinking system, as an anti-reversion agent.
• a and B together form a covalent bond is meant that the sulfur atoms adjacent to A and B respectively are connected directly by a covalent bond.
• the polysulfurized compound of general formula (I) is cyclic.
• divalent hydrocarbon group in the sense of the present invention a group comprising carbon and hydrogen atoms. This group may optionally be interrupted by at least one heteroatom.
• the hydrocarbon group may be optionally branched, in particular substituted with C 1 -C 6 alkyl groups, with phenyl or with benzyl.
• the hydrocarbon group may also and preferably be linear, that is to say, it is not branched. It can also be cyclical. Whatever its linear, cyclic or branched form, it may optionally comprise one or more carbon-carbon double bonds.
• heteroatom is meant in the sense of the present invention, the sulfur atoms, the nitrogen atoms, the silicon atoms and the phosphorus atoms.
• R 1 and R 2 represent, independently of one another, alkylene radicals containing from 1 to 18 carbon atoms, preferably from 2 to 10 carbon atoms, more more preferably from 2 to 8 carbon atoms.
• Ri and R 2 are identical.
• R 1 and R 2 represent, independently of each other, identical or different groups, preferably identical groups, chosen from the group formed by -CH 2 (CH 2)
• p represents a number in a range from 1 to 30, preferably from 1 to 15, more preferably from 1 to 3.
• a and B form a covalent bond.
• the polysulfide compound of general formula (I) is a cyclic compound.
• A represents a hydrogen atom and B represents a hydrogen atom or a -SH group; more preferably A and B represent a hydrogen atom.
• the polysulfide compound of general formula (I) is a non-cyclic compound.
• polysulfide compounds of general formula (I) may be mixtures of polysulfide compounds of general formula (I) in which case the indices m and p are average values. These indices can therefore be integers like fractional numbers.
• the polysulfurized compound of general formula (I) can be in the form of a mixture of cyclic and non-cyclic form.
• the polysulphurized compounds in which A and B together form a covalent bond, Ri and R 2 are C 2 -C 10 alkylenes, preferably C 2 -Cs, m represents 1 and p representing a number within a range of 1 to 3, preferably p 1, are preferred compounds.
• these polysulfide compounds when used in the compositions of the invention make it possible to overcome the phenomenon of reversion.
• the polysulphurized compounds in which A and B together form a covalent bond, R 1 and R 2 are C 2 -C 10 alkylenes, preferably C 2 -C 6 alkyls, represents 2 and p representing a number within a range of 1 to 3, preferably p 1, are preferred compounds.
• these polysulfide compounds when used in the compositions of the invention make it possible to overcome the phenomenon of reversion.
• polysulphide compounds of the general formula (I) polysulphide compounds wherein A and B are hydrogen, Ri and R 2 are alkylene C 2 -C 0, preferably C 2 -Cs m represents 1 and p represents a number in a range from 1 to 30 are also particularly preferred compounds.
• the level of the polysulfurized compound of general formula (I), including their embodiments and their preferred variants, in the composition of the present invention is in a range from 0.5 to 10 phr, of preferably ranging from 0.5 to 5 phr, preferably from 0.5 to 3 phr.
• polysulfide compound of general formula (I), including their embodiments and their preferred variants, may be used alone in the composition of the invention or in combination with one or more co-crosslinking agents.
• co-crosslinking agents are well known to those skilled in the art and can be incorporated during the first non-productive phase and / or during the productive phase of manufacture of the composition as described later.
• co-agents may be vulcanization activators, vulcanization accelerators, well known to those skilled in the art.
• stearic acid derivative As vulcanization activators, mention may be made of zinc oxide and stearic acid derivatives.
• stearic acid salt As an example of a stearic acid salt that may be used in the context of the present invention, there may be mentioned in particular zinc or magnesium stearate.
• vulcanization accelerators well known to those skilled in the art, one will preferably choose from the group consisting of thiazoles, sulfenamides, guanidines, amines, aldehyde-amines, dithiophosphates, xanthates thiurams, dithiocarbamates and mixtures thereof.
• benzothiazyl-2-cyclohexyl sulfenamide CBS
• benzothiazyldicyclohexy-1 sulfenamide DCBS
• benzothiazoyl-2-tert.-butyl sulfenamide TBBS
• 2- mercaptobenzothiazole MCT
• benzothiazole disulfide MBTS
• ZMBT benzothiazyl-2-sulfene morpholide
• MPS benzothiazyl-2-sulfene morpholide
• DPG guanidine diphenyl
• TPG triphenyl guanidine
• DPG diorthotolyl guanidine
• DOG diorthotolyl guanidine
• OTBG o-tolylbiguanide
• benzothiazole disulfide MBTS
• TMTD tetramethylthiuram dis
• the composition of the invention comprises at least one complementary vulcanization accelerator, different from the accelerator described above, selected from the group consisting of diphenyl guanidine (DPG), triphenyl guanidine (TPG), diorthotolyl guanidine (DOTG), o-tolylbiguanide (OTBG), benzothiazole disulfide (MBTS), tetramethylthiuram disulfide (TMTD), tetrabenzylthiuram disulfide (TBzTD), zinc dibenzyldithiocarbamate (ZBEC) ), zinc N, N'-dimethylcarbamodithioates (ZDMC), zinc N, N'-diethylcarbamodithioates (ZDEC), zinc N, N'-dibutylcarbamodithioates (ZDBC), zinc N, N'-dibenzylcarbamodithioates (ZDBC), zinc isopropylxanthat
• DPG diphen
• the complementary vulcanization accelerator is zinc dibenzyldithiocarbamate (ZBEC).
• ZBEC zinc dibenzyldithiocarbamate
• the compositions of the invention also have an improvement of the elongation breaking at low mechanical stresses.
• polysulfide compounds of general formula (I) useful for the invention may be prepared by any means known to those skilled in the art.
• a process generally comprising a step of reacting a sulfur compound with a compound of formula (II) according to the following reaction scheme can be used.
• the polysulfide compounds of general formula (I) may in particular be obtained by an oxidative coupling reaction of the alkylthiol precursors, corresponding arylthiols.
• all the reactions described in the following references make it possible to obtain disulfide compounds by oxidative coupling.
• compositions according to the invention with only the ingredients described above are sufficient to respond to the technical problem, particularly that to obtain compositions having mechanical properties, in particular elongation breaking properties, improved with high mechanical stresses.
• compositions of the invention may further comprise additional ingredients.
• the composition of the invention further comprises at least one filler; that is to say a single charge or a mixture of several charges.
• compositions of the invention comprise a reinforcing filler or a mixture of several reinforcing fillers.
• the term "reinforcing filler” is intended to mean any type of filler known for its ability to reinforce a rubber composition which can be used in particular for the manufacture of a tire, for example an organic filler such as carbon or even a reinforcing inorganic filler.
• the reinforcing filler is selected from carbon black, a reinforcing inorganic filler (preferably silica) and mixtures thereof.
• the reinforcing filler comprises carbon black.
• carbon blacks are suitable for all carbon blacks, including the black type HAF, ISAF, SAF conventionally used in tires (so-called pneumatic grade black).
• the reinforcing carbon blacks of the 100, 200 or 300 series for example the N115, N134, N234, N326, N330, N339, N347 or N375 blacks, or even targeted applications, blacks of higher series (eg N660, N683, N772).
• the carbon blacks could for example already be incorporated into an isoprene elastomer in the form of a masterbatch (see for example WO 97/36724 or WO 99/16600).
• carbon blacks are preferentially suitable reinforcing carbon blacks having a specific surface CT AB (determined according to the French standard NF T 45-007 November 1987, method B) greater than or equal to 90 m 2 / g. More preferentially, carbon blacks having a specific surface area are suitable. higher CTAB greater than or equal to 120 m 2 / g, more preferably a specific surface CTAB in a range from 120 m 2 / g to 180 m 2 / g.
• the reinforcing filler may comprise an organic filler other than carbon black.
• organic fillers other than carbon blacks mention may be made of functionalized polyvinyl organic fillers such as those described in applications WO-A-2006/069792, WO-A-2006/069793, WO-A-1, 2008/003434 and WO-A-2008/003435.
• the reinforcing filler may comprise a reinforcing inorganic filler, preferably a silica.
• any inorganic or mineral filler (whatever its color and origin (natural or synthetic), also called “white” charge, charge “Clear” or “non-black filler” as opposed to carbon black, capable of reinforcing on its own, with no other means than an intermediate coupling agent, a rubber composition for manufacturing tire, in other words able to replace, in its reinforcing function, a conventional carbon black pneumatic grade, such a charge is generally characterized, in known manner, by the presence of hydroxyl groups (-OH) at its area.
• -OH hydroxyl groups
• reinforcing inorganic filler is present indifferent, whether in the form of powder, microbeads, granules, beads or any other suitable densified form.
• reinforcing inorganic filler also refers to mixtures of different reinforcing inorganic fillers, in particular highly dispersible siliceous and / or aluminous fillers as described below.
• reinforcing inorganic fillers are especially suitable mineral fillers of the siliceous type, in particular of silica (SiO 2 ), or of the aluminous type, in particular of alumina (Al 2 O 3).
• the composition may contain a type of silica or a blend of several silicas.
• the silica used may be any reinforcing silica known to those skilled in the art, in particular any precipitated or fumed silica having a BET specific surface and a CTAB specific surface area both less than 450 m 2 / g, preferably from 30 to 400 m 2 / g.
• the BET surface area is determined by gas adsorption using the Brunauer-Emmett-Teller method described in "The Journal of the American Chemical Society "(Vol 60, page 309, February 1938), and more precisely according to a method adapted from standard NF ISO 5794-1, annex E of June 2010 [multipoint volumetric method (5 points) - gas: nitrogen - degassing under vacuum: one hour at 160 ° C - relative pressure range p / po: 0.05 to 0.2]
• HDS highly dispersible precipitated silicas
• a reinforcing inorganic filler is present in the composition, in particular a silica
• at least one bifunctional coupling agent intended to ensure a sufficient connection, of a chemical nature and or physical, between the inorganic filler (surface of its particles) and the diene elastomer, in particular organosilanes or bifunctional polyorganosiloxanes.
• polysulfide silanes called “symmetrical” or “asymmetrical” silanes, depending on their particular structure, are used, as described for example in the applications W003 / 002648 (or US 2005/016651) and W003 / 002649 (or US 2005 / 016650).
• the rubber compositions according to the invention contain coupling agents, their level is preferably in a range from 4 to 12 phr, more preferably from 3 to 8 phr.
• compositions may optionally also contain, in addition to the coupling agents, coupling activators, inorganic charge-covering agents or, more generally, processing aid agents capable in a known manner, by virtue of a improvement of the dispersion of the filler in the rubber matrix and a lowering of the viscosity of the compositions, to improve their ability to use in the green state, these agents, well known to those skilled in the art , being for example hydrolysable silanes such as alkylalkoxysilanes, polyols, fatty acids, polyethers, primary, secondary or tertiary amines, hydroxylated or hydrolysable polyorganosiloxanes.
• these agents well known to those skilled in the art , being for example hydrolysable silanes such as alkylalkoxysilanes, polyols, fatty acids, polyethers, primary, secondary or tertiary amines, hydroxylated or hydrolysable polyorganosiloxanes.
• polysulfide silanes called “symmetrical” or “asymmetrical” silanes according to their particular structure, are used, as described, for example, in claims WO 03/002648 (or US 2005/016651) and WO 00/002649 (or US 2005/016650).
• this total content of reinforcing filler is in a range from 5 to 250 phr, preferably from 40 to 200 phr.
• the reinforcing filler (or a reinforcing filler mixture) comprises mainly by weight of carbon black.
• the carbon black used as a reinforcing filler is predominant in weight; that is to say, it represents the highest rate in phr among the reinforcing fillers of the composition.
• the carbon black represents more than 50% by weight (> 50% by weight) of the total weight of the reinforcing filler, preferably more than 60% by weight.
• Other types of reinforcing filler may be used in a minor minority relative to carbon black in the compositions according to the invention, in particular other reinforcing organic fillers or reinforcing inorganic fillers such as silica.
• a reinforcing inorganic filler is a minority when its weight does not represent the highest level in phr of the reinforcing fillers of the composition; that is to say, the reinforcing inorganic filler represents less than 50% by weight ( ⁇ 50% by weight) of the total weight of the reinforcing filler, preferably less than 40% by weight.
• the level of carbon black in the composition of the invention is then preferably in a range from 20 to 150 phr, preferably from 30 to 90 phr, more preferably from 35 to 90 phr. 80 phr, the optimum being of course differ according to the particular applications targeted.
• the silica content in the composition is preferably less than 10 phr.
• the reinforcing filler (or a reinforcing filler mixture) comprises mainly by weight of the silica.
• the silica used as reinforcing filler is predominant in weight; that is to say, it represents the highest rate in phr among the reinforcing fillers of the composition.
• the silica represents more than 50% by weight (> 50% by weight) of the total weight of the reinforcing filler, preferably more than 60% by weight.
• Other types of reinforcing filler may be used in a minor proportion to the silica in the compositions according to the invention, in particular other reinforcing organic fillers such as carbon black.
• Carbon black is a minority when its weight does not represent the highest level in phr of the reinforcing fillers of the composition; that is to say that the carbon black represents less than 50% by weight ( ⁇ 50% by weight) of the total weight of the reinforcing filler, preferably less than 40% by weight.
• the level of silica in the composition of the invention is then preferably in a range from 20 to 150 phr, preferably from 30 to 90 phr, more preferably from 35 to 80 phr, the optimum being of course differ according to the particular applications concerned.
• the content of carbon black in the composition is preferably less than 10 phr, and more preferably 5 phr.
• the composition of the invention may comprise at least one semi-reinforcing filler.
• the semi-reinforcing fillers are not capable of reinforcing by themselves a rubber composition intended for the manufacture of tires, in other words they are not able to replace, in its reinforcing function, a conventional carbon black of pneumatic grade, however they allow an increase in tensile modulus of a rubber composition in which they are incorporated, that is why they are called "semi-reinforcing".
• As a semi-reinforcing filler mention may be made of graphite.
• the composition of the invention may comprise at least one inert filler.
• the inert fillers that may be used in the compositions of the invention may be chosen from chalk, clay, bentonite, talc, kaolin, glass microbeads, glass flakes and a mixture of these compounds.
• compositions of the invention may optionally additionally comprise all or part of the usual additives usually used in elastomer compositions, for example pigments, protective agents such as anti-ozone waxes, anti- chemical ozonants, antioxidants, plasticizing agents such as plasticizing oils or hydrocarbon resins well known to those skilled in the art, reinforcing resins, acceptors (for example phenolic novolak resin) or methylene donors (for example HMT or H3M).
• additives usually used in elastomer compositions for example pigments, protective agents such as anti-ozone waxes, anti- chemical ozonants, antioxidants, plasticizing agents such as plasticizing oils or hydrocarbon resins well known to those skilled in the art, reinforcing resins, acceptors (for example phenolic novolak resin) or methylene donors (for example HMT or H3M).
• additives usually used in elastomer compositions for example pigments, protective agents such as anti-ozone waxes, anti- chemical ozonants,
• compositions of the present invention may be used for the manufacture of articles.
• Another object of the present invention relates to an article comprising at least one composition as defined above.
• pneumatic object in the sense of the present invention any object that takes its usable form when inflated with a gas (or gas) inflation such as air for example.
• pneumatic objects examples include pneumatic boats, pneumatic tires, balls or balls used for play or sport.
• the article comprising at least one composition according to the invention is a pneumatic object, preferably a pneumatic tire.
• This tire may be intended to equip including non-motorized vehicles such as bicycles, tourism-type motor vehicles, SUV (Sport Utility Vehicles), two wheels (including motorcycles), aircraft, industrial vehicles chosen among vans, heavy goods vehicles (ie metro, buses, road machinery (trucks and trailers)), off-road vehicles, such as agricultural or civil engineering machinery, others transport or handling vehicles.
• non-motorized vehicles such as bicycles, tourism-type motor vehicles, SUV (Sport Utility Vehicles), two wheels (including motorcycles), aircraft, industrial vehicles chosen among vans, heavy goods vehicles (ie metro, buses, road machinery (trucks and trailers)), off-road vehicles, such as agricultural or civil engineering machinery, others transport or handling vehicles.
• Another article may be a semi-finished product for pneumatic tires. It can be any type of rubber, such as in particular treads, underlays, sidewalls, layers of beads, layers of protectors, sheets of underlays, sheets of rubber blocks .
• foam articles based on the above composition and of blowing agents having insulating, sound-absorbing, anti-vibration or reinforcement properties, used in the field of sport and recreation-as a structure balloon, protective epaulette.
• foam or “foam structure” is meant an object or article or material of lower density than that of the starting material.
• compositions are manufactured in suitable mixers, for example using two successive preparation phases according to a general procedure well known to those skilled in the art: a first phase of work or thermomechanical mixing (sometimes referred to as "non-phase" phase). at high temperature, up to a maximum temperature of between 130.degree. C. and 200.degree. C., preferably between 145.degree. C. and 185.degree. C., followed by a second phase of mechanical work (sometimes referred to as a productive phase). ) At a lower temperature, typically below 120 ° C, for example between 60 ° C and 100 ° C, finishing phase during which is incorporated the crosslinking agent or the crosslinking system.
• Another object of the present invention relates to a method of manufacturing a composition
• a composition comprising at least one unsaturated polymer, at least one filler, preferably a reinforcing filler as described above and at least one compound.
• a and B together form a covalent bond or A represents a hydrogen atom and B represents a hydrogen atom or a -SH group;
• n is a number in a range from 1 to 3;
• p is a number greater than or equal to 1;
• R 1 and R 2 represent, independently of one another, identical or different divalent hydrocarbon groups containing from 1 to 18 carbon atoms, optionally interrupted by a heteroatom;
• said method comprising at least the following steps:
• step (a) the filler is mixed with the unsaturated polymer in a mixer; b) the mixture of step (a) is mechanically kneaded one or more times until a maximum temperature of less than or equal to 200 ° C. is reached; ,
• step (b) cooling the mixture obtained at the end of step (b) to a temperature below 100 ° C; d) is incorporated in the mixture obtained at the end of step (c) said polysulfurized compound of general formula (I) and,
• step (d) kneading the mixture obtained at the end of step (d) to a temperature below 120 ° C.
• the method may further comprise a step (f) during which the composition obtained at the end of step e) is extruded or calendered.
• the method may further comprise a step (g) during which the mixture obtained is heated at the end of step (e) or the extruded or calendered composition obtained at the end of step (f) at a temperature greater than or equal to 130 ° C, preferably in the range of 130 ° C to 200 ° C.
• the first phase is conducted in a single thermomechanical step during which is introduced into a suitable mixer such as a conventional internal mixer, all the necessary constituents, the possible additional coating or processing agents and other miscellaneous additives, with the exception of the polysulfide compound of general formula (I), (including these preferred embodiments and its preferred variants) or the crosslinking system comprising the polysulfide compound of general formula (I), (including these preferred embodiments and its preferred variants) and the co-agent.
• the polysulfurized compound of general formula (I) including these preferred embodiments and its preferred variants
• the crosslinking system comprising the polysulfurized compound is then incorporated.
• the crosslinking (or cooking) is carried out according to any procedure known to those skilled in the art, at a temperature, at a pressure and for a suitable duration depending on the nature and use of the composition.
• the crosslinking is carried out in a known manner at a temperature generally greater than or equal to 130.degree. C., in a range from 130.degree. C. to 200.degree. C., for a sufficient time which may vary, for example, between 5 and 90.degree. min. 2.4
• Another object of the invention relates to the use of at least one polysulfurized compound of general formula (I) as a crosslinking agent for unsaturated polymers.
• a and B together form a covalent bond or A represents a hydrogen atom and B represents a hydrogen atom or a -SH group;
• n is a number in a range from 1 to 3;
• p is a number greater than or equal to 1;
• R 1 and R 2 represent, independently of one another, identical or different divalent hydrocarbon groups containing from 1 to 18 carbon atoms, optionally interrupted by a heteroatom.
• polysulfide compounds of general formula (I) also apply to this use as a crosslinking agent for unsaturated polymers.
• the polymers are elastomers, more preferably diene elastomers, as described above.
• Another object of the present invention relates to a process for crosslinking unsaturated polymers, said process comprising at least the following steps:
• Another object of the present invention relates to a crosslinking system comprising at least one vulcanization accelerator and at least one polysulfurized compound of general formula (I) as described above, including embodiments and preferred variants. previously described.
• Vulcanization accelerators are well known to those skilled in the art and have been described above.
• the vulcanization accelerator is selected from the group consisting of thiazoles, sulfenamides, guanidines, amines, aldehyde amines, dithiophosphates, xanthates, thiurams, dithiocarbamates and mixtures thereof.
• a vulcanization accelerator from benzothiazyl-2-cyclohexyl sulfenamide (CBS), benzothiazyldicyclohexy-1 sulfenamide (DCBS), benzothiazoyl-2-tert-butyl.
• TBBS sulfenamide
• MCT 2-mercaptobenzothiazole
• MBTS benzothiazole disulfide
• ZMBT 2-mercaptobenzothiazole zinc or sodium salt
• benzothiazyl-2-sulfene morpholide MS
• DPG diphenyl guanidine
• TPG triphenyl guanidine
• DDG diorthotolyl guanidine
• OTBG o-tolylbiguanide
• benzothiazole disulfide MBTS
• TMTD tetramethylthiuram disulfide
• TBzTD tetrabenzylthiuram disulfide
• ZBEC zinc dibenzyldithiocarbamate
• ZDMC zinc N, N'-dimethylcarbamodithioates
• ZDEC zinc N, N'-diethylcarbamodithioates
• ZDEC zinc N, N'-dibut
• the crosslinking system comprises a complementary vulcanization accelerator, different from the accelerator described above, selected from the group consisting of diphenyl guanidine (DPG), triphenyl guanidine (GPT). , diorthotolyl guanidine (DOTG), o-tolylbiguanide (OTBG), benzothiazole disulfide (MBTS), tetramethylthiuram disulfide (TMTD), tetrabenzylthiuram disulfide (TBzTD), zinc dibenzyldithiocarbamate (ZBEC), zinc N, N'-dimethylcarbamodithioates (ZDMC), zinc N, N'-diethylcarbamodithioates (ZDEC), zinc N, N'-dibutylcarbamodithioates (ZDBC), zinc N, N'-dibenzylcarbamodithioates (ZDBC), zinc isopropylxanthate
• DPG diphen
• the vulcanization accelerators are available commercially from many suppliers such as Nocil, Lanxess, Flexsys for example.
• the crosslinking system of the invention may further comprise a stearic acid derivative and zinc oxide.
• stearic acid derivative stearic acid or a salt of stearic acid, both of which are well known to those skilled in the art.
• stearic acid salt there may be mentioned in particular zinc or magnesium stearate.
• compositions comprising an unsaturated polymer reinforced with an inorganic filler, these compositions differing from each other by the following technical characteristic:
• composition Cl is a non-compliant composition comprising elemental sulfur as a crosslinking agent
• composition C2 is a compliant composition comprising a polysulfide compound of general formula (I): 1,8-dithiacyclotetradecane 1,8-disulfide;
• composition C3 is a composition according to the invention comprising a polysulfurized compound of general formula (I): 1,2,5-trithieadlane;
• composition C4 is a non-compliant composition comprising elemental sulfur as a crosslinking agent and zinc dibenzyldithiocarbamate (ZBEC) as a complementary vulcanizing agent;
• ZBEC zinc dibenzyldithiocarbamate
• composition C5 is a compliant composition comprising a polysulfide compound of general formula (I): 1,8-dithiacyclotetradecane 1,8-disulfide and zinc dibenzyldithiocarbamate (ZBEC) as a complementary vulcanizing agent;
• a polysulfide compound of general formula (I): 1,8-dithiacyclotetradecane 1,8-disulfide and zinc dibenzyldithiocarbamate (ZBEC) as a complementary vulcanizing agent
• composition C6 is a composition according to the invention comprising a polysulfide compound of general formula (I), 1,2,5-trithiepane, and zinc dibenzyldithiocarbamate (ZBEC) as complementary vulcanizing agent.
• a polysulfide compound of general formula (I) 1,2,5-trithiepane
• ZBEC zinc dibenzyldithiocarbamate
• the 1,8-dithiacyclotetradecane 1,8-disulfide is synthesized according to the reaction scheme No. 1 and according to the following synthesis protocol:
• the solvents are evaporated under reduced pressure (70 mbar, 36 ° C.).
• the expected product is treated with MTBE (350 mL) and washed 3 times with water (50 mL).
• the organic phase is dried with sodium sulphate and then concentrated under reduced pressure (35 mbar, 36 ° C.).
• 1,6-hexanedithiol is obtained whose molar purity is greater than 97 mol%. (1H NMR).
• the solid is treated twice with acetone (twice for 250 ml): after stirring for 3 hours at room temperature, the precipitate is filtered and washed on the filter with acetone (twice per 25 ml). After drying, the product is treated with MBTE (200 ml) with stirring for 3 hours at room temperature, then the residual solid is filtered and washed with MTBE (twice for 15 ml) and finally dried for 10-15 hours at room temperature. . A white solid (20.09 g, 85% yield) melting point 62 ° C is obtained.
• the molar purity is greater than 94% (1H NMR).
• compositions C1 to C6 The formulation of compositions C1 to C6 is shown in Table I. The amounts are expressed in parts per 100 parts of elastomers (phr). The compositions are formulated with iso-mole of sulfur.
• Coupling agent bis (triethoxysilylpropyl) tetrasulfide sold under the reference “Si69” (liquid silane) from the company Evonik;
• compositions For the preparation of these compositions, the procedure is as follows: - is introduced into an internal mixer of 400 cm 3 pallets type "Banburry", filled to 70% and whose initial temperature of the tank is about 60 ° C, diene elastomer, carbon black, antioxidant, zinc oxide and stearic acid. We conducts thermomechanical work until the temperature of the mixture is about 100 ° C. A first shot of pestle, bringing chaos in the mixture, is then achieved. When the mixture reaches about 140 ° C, a second pestling is performed. Thermomechanical work is continued for about 4 minutes to reach a maximum "fallout" temperature of 160 ° C.
• the mixture thus obtained is recovered and cooled on an external mixer at room temperature (23 ° C.).
• the polysulfide compound ((8) or (9) depending on the composition) and the complementary vulcanization accelerator are incorporated into the mixture on the external mixer (homoformer), then twelve passes in the portfolio are made in order to homogenize the mixture.
• compositions are then calendered in the form of rubber plates with a thickness of 2 to 3 mm for measuring the rheometric and mechanical properties.
• compositions indicated below are those measured after firing (or crosslinking) at t 90 (cf method DIN 53529) at 150 ° C. or at 190 ° C.
• compositions C2 and C3 according to the invention and comprising a polysulfide compound of formula (I) exhibit an improvement in the elongation rupture measured at 100 ° C. with respect to the composition Cl not according to the invention comprising sulfur as crosslinking agent. These results are observable whatever the cooking temperature.
• composition C3 according to the invention has, in addition, the advantage of not having a reversion phenomenon at high cooking temperatures.
• compositions C1 and C3 When adding to the non-conforming composition C1 which comprises sulfur as crosslinking agent and a complementary vulcanization accelerator, a composition C4 not according to the invention is obtained.
• This non-compliant composition C4 exhibits an increase in the reversion rate at the high firing temperatures (comparison compositions Cl and C4).
• the same complementary vulcanization accelerator when adding to the compositions C2 and C3 according to the invention the same complementary vulcanization accelerator to obtain compositions C5 and C6 according to the invention, we observe:
• composition C5 a reduction in the reversion rate at the high firing temperatures for composition C5 (comparison of compositions C2 and C5);
• composition C6 (comparison compositions C3 and C6)

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