Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07F—ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
  • C07F7/00—Compounds containing elements of Groups 4 or 14 of the Periodic Table
  • C07F7/02—Silicon compounds
  • C07F7/08—Compounds having one or more C—Si linkages
  • C07F7/0834—Compounds having one or more O-Si linkage
  • C07F7/0836—Compounds with one or more Si-OH or Si-O-metal linkage
• • 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
• • 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
  • C08K7/00—Use of ingredients characterised by shape
  • C08K7/02—Fibres or whiskers
  • C08K7/04—Fibres or whiskers inorganic
  • C08K7/14—Glass
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L9/00—Compositions of homopolymers or copolymers of conjugated diene hydrocarbons
  • C08L9/06—Copolymers with styrene

Definitions

• the present invention relates to mercaptosilane coupling agents, which can be used in particular for coupling reinforcing inorganic fillers and diene elastomers in rubber compositions intended for example for the manufacture of tires.
• the filler in general, in order to obtain the optimum reinforcement properties conferred by a filler, the filler should be present in the elastomeric matrix in a final form which is at once as finely divided as possible and distributed in the as homogeneous as possible.
• the load has a very good ability, on the one hand to incorporate into the matrix during mixing with the elastomer and to deagglomerate, on the other hand to to disperse homogeneously in this matrix.
• Such rubber compositions comprising reinforcing inorganic fillers of the siliceous or aluminous type, have for example been described in patents or patent applications EP-A-0501227 (or US-A-5227425), EP-A-0735088 (or USA- 5852099), EP-A-0810258 (or US-A-5900449), EP-A-0881252, WO99 / 02590, WO99 / 02601, WO99 / 02602, WO99 / 28376, WO00 / 05300, WO00 / 05301.
• a coupling agent also called binding agent, whose function is to ensure the connection between the surface of the inorganic filler particles and the elastomer, while facilitating the dispersion of this load inorganic within the elastomeric matrix.
• coupling agent inorganic filler / elastomer
• inorganic filler / elastomer means, in a known manner, an agent capable of establishing a sufficient bond, of a chemical and / or physical nature, between the inorganic filler and the elastomer. diene; such a coupling agent, at least bifunctional, has for example as simplified general formula "Y-W-X", in which:
• Y represents a functional group ("Y" function) which is capable of binding physically and / or chemically to the inorganic filler, such a bond being able to be established, for example, between a silicon atom of the coupling agent and the surface hydroxyl (OH) groups of the inorganic filler (for example surface silanols in the case of silica);
• X represents a functional group ("X" function) capable of binding physically and / or chemically to the diene elastomer, for example via a sulfur atom; W represents a divalent group for connecting Y and X.
• the coupling agents must not be confused with simple inorganic filler agents which, in known manner, can comprise the active Y function with respect to the inorganic filler but lack the active X function. with the diene elastomer.
• mercaptosilanes are particularly interesting, however, given their very high reactivity, blocked mercaptosilanes are generally used.
• blocked mercaptosilanes in a manner well known to those skilled in the art, are precursors of silanes capable of forming mercaptosilanes during the preparation of the rubber compositions (see for example US 2002/0115767 A1 or the application International Patent WO 02/48256).
• the blocked mercaptosilanes are capable of being released by replacement of the blocking group by a hydrogen atom, during mixing and firing, to lead to the formation of a more reactive mercaptosilane, defined as a silane whose molecular structure contains at least one thiol (-SH) (mercapto) group bonded to a carbon atom and at least one silicon atom.
• a more reactive mercaptosilane defined as a silane whose molecular structure contains at least one thiol (-SH) (mercapto) group bonded to a carbon atom and at least one silicon atom.
• These blocked mercaptosilane coupling agents are thus generally used in the presence of blocked mercaptosilane activator whose role is to initiate, accelerate or enhance the activity of the blocked mercaptosilane, as specified in particular in US Pat. 590.
• Such an activator or "deblocking agent” for tire rubber compositions generally consists of guanidine, particularly ⁇ , ⁇ '-diphenylguanidine, DPG.
• vulcanization of diene elastomers by sulfur is widely used in the rubber industry, in particular in that of the tire.
• a relatively complex vulcanization system comprising, in addition to sulfur, various vulcanization accelerators and one or more vulcanization activators, especially zinc derivatives such as zinc oxide (ZnO) zinc salts of fatty acids such as zinc stearate.
• ZnO zinc oxide
• a medium-term objective of tire manufacturers is to remove zinc or its derivatives from their rubber formulations, because of the relatively toxic nature of these compounds, particularly with respect to water and aquatic organisms (classification R50 according to European Directive 67/548 / EC of 9 December 1996).
• compositions comprising silica and specific blocked mercaptosilanes as coupling agent, surprisingly allows the coupling agent to react without need the presence of a deblocking agent and without degradation of the properties of this composition.
• R 1 which are identical or different, each represent a monovalent hydrocarbon group chosen from alkyls, linear or branched, cycloalkyls or aryls, having from 1 to 18 carbon atoms;
• the symbol A represents hydrogen or a monovalent hydrocarbon group chosen from alkyls, linear or branched, cycloalkyls or aryls, having from 1 to 18 carbon atoms and linear or branched alkoxyalkyls having from 2 to 8 carbon atoms;
• the symbol Z represents a divalent linking group having from 1 to 18 carbon atoms.
• the invention furthermore relates to a process for obtaining a mercaptosilane general formula (I) which comprises the following steps: starting from a blocked mercaptosilane (hereinafter product B) of formula (B):
• RI, A and Z have the same meaning as in formula (I);
• R2 which may be identical or different, represent a monovalent hydrocarbon group chosen from alkyls having from 1 to 6, preferably from 1 to 3; acid hydrolysis is carried out to obtain the blocked mercaptosilane of formula (I).
• the rubber compositions, in which the coupling agents are tested, are characterized before and after firing, as indicated below.
• the dynamic properties AG * and tan ( ⁇ ) max are measured on a viscoanalyzer (Metravib VA4000) according to ASTM D 5992-96.
• the response of a sample of vulcanized composition (cylindrical test specimen 4 mm in thickness and 400 mm 2 in section) is recorded, subjected to a sinusoidal stress in simple shear. alternately, at a frequency of 10 Hz, at 23 ° C or 40 ° C.
• a strain amplitude sweep of from 0.1 to 50% (forward cycle) is carried out and then from 50% to 1% (return cycle).
• the results exploited are the complex dynamic shear modulus (G *) and the loss factor (tan ⁇ ).
• G * complex dynamic shear modulus
• tan ⁇ the loss factor
• the maximum value of tan ⁇ observed (tan ( ⁇ ) max ) and the complex modulus difference (AG *) between the values at 0, 1%> and 50%> deformation are indicated. (Payne effect).
• the first subject of the invention is a mercaptosilane general formula (I):
• R 1 represents a monovalent hydrocarbon group selected from alkyls, linear or branched, cycloalkyls or aryls, having from 1 to 18 carbon atoms;
• A represents hydrogen or a monovalent hydrocarbon group chosen from alkyls, linear or branched, cycloalkyls or aryls, having from 1 to 18 carbon atoms,
• Z represents a divalent linking group having from 1 to 18 carbon atoms.
• Z may contain one or more heteroatoms selected from O, S and N.
• R 1 is selected from methyl, ethyl, n-propyl and isopropyl, preferably from methyl and ethyl;
• A is selected from alkyls having from 1 to 18 carbon atoms and the phenyl radical;
• Z is selected from alkylenes and Ci -C s arylene, C 6 -C 12. According to one embodiment, Z is chosen from C1-C10 alkylenes and more preferably Z is chosen from C 1 -C 4 alkylenes.
• R 1 is methyl.
• A is chosen from alkyls having from 1 to 7 carbon atoms and the phenyl radical.
• RI, A and Z have the same meaning as in formula (I);
• R2 which may be identical or different, represent a monovalent hydrocarbon group chosen from alkyls having from 1 to 6, preferably from 1 to
• the product B can in particular be obtained from an "unsealed mercaptosilane" by subjecting it to thio-aesthification.
• the compound of the invention finds an advantageous industrial application as a coupling agent, intended for example to ensure the bonding or adhesion between a reactive polymeric matrix (in particular a rubber matrix) and any hydroxyl surface material, in particular mineral (for example, glass fiber) or metal (for example, carbon steel or stainless steel wire).
• a reactive polymeric matrix in particular a rubber matrix
• any hydroxyl surface material in particular mineral (for example, glass fiber) or metal (for example, carbon steel or stainless steel wire).
• reinforcing inorganic filler is meant in known manner, an inorganic or mineral filler, regardless of its color and origin (natural or synthetic), also called “white” filler or sometimes “clear” filler as opposed to black of carbon, this inorganic filler being capable of reinforcing on its own, without any other means than an intermediate coupling agent, a rubber composition intended for the manufacture of tires, in other words capable of replacing, in its reinforcing function, a load conventional pneumatic grade carbon black.
• the diene elastomer is then preferably selected from the group of highly unsaturated diene elastomers consisting of polybutadienes (BR), synthetic polyisoprenes (IR), natural rubber (NR), butadiene copolymers styrene (SBR), butadiene-isoprene copolymers (BIR), butadiene-acrylonitrile copolymers (NBR), isoprene-styrene copolymers (SIR), butadiene-styrene-isoprene copolymers (SBIR) and blends of these elastomers.
• BR polybutadienes
• IR synthetic polyisoprenes
• NR natural rubber
• SBR butadiene copolymers styrene
• BIR butadiene-isoprene copolymers
• NBR butadiene-acrylonitrile copolymers
• SIR isoprene-sty
• the diene elastomer is then preferably an SBR or a blend (mixture) of SBR and another diene elastomer such as BR, NR or IR.
• an SBR elastomer use is made in particular of an SBR having a styrene content of between 20% and 30% by weight, a vinyl bond content of the butadiene part of between 15% and 65%, a bond content of trans-1,4 between 15% and 75% and a glass transition temperature ("Tg" - measured according to ASTM D3418-82) between -20 ° C and -55 ° C, this copolymer SBR, preferably prepared in solution (SSBR), optionally being used in admixture with a polybutadiene (BR) preferably having more than 90%) cis-1,4 bonds.
• SSBR polybutadiene
• the diene elastomer is then preferably an isoprene elastomer, that is to say a diene elastomer selected from the group consisting of natural rubber (NR). ), the synthetic polyisoprenes (IR), the various isoprene copolymers and the mixtures of these elastomers; it is then more preferentially natural rubber or a synthetic polyisoprene of the cis-1,4 type having a content (mol%) of cis-1,4 bonds greater than 90%>, more preferably still greater than 98 %>.
• NR natural rubber
• IR synthetic polyisoprenes
• the various isoprene copolymers the mixtures of these elastomers
• the blocked mercaptosilanes of the invention have proved to be sufficiently effective on their own for the coupling of a diene elastomer and a reinforcing inorganic filler such as silica, used at a preferential rate greater than 1 phr (parts by weight per cent parts of elastomer), more preferably between 2 and 20 phr. They may advantageously be the only coupling agent present in inorganic-load-reinforced rubber compositions for the manufacture of tires.
• mineral fillers of the siliceous type in particular of silica (SiO 2 ), or of the aluminous type, in particular alumina (Al 2 O 3 ) or (oxide) hydroxides, aluminum, or reinforcing titanium oxides, as described in the aforementioned patents or patent applications.
• silica silica
• aluminous type in particular alumina (Al 2 O 3 ) or (oxide) hydroxides, aluminum, or reinforcing titanium oxides, as described in the aforementioned patents or patent applications.
• Product B is prepared by hydrolysis in a catalytic acid medium.
• demineralized water 60 ml
• acetone 300 ml
• S-octanoylmercaptopropylethoxydimethylsilane A 59.0 g, 0.194 mol
• the solution is stirred for 1.5-2 hours at room temperature.
• the mixture obtained is chromatographed on a silica column (eluent mixture of petroleum ether and ethyl acetate in a ratio of 1: 1).
• an oil 41 g, 0.148 mol, yield of 76%) is obtained.
• NMR analysis confirms the structure of S-octanoylmercaptopropylhydroxydimethylsilane obtained with a molar purity higher than 97%.
• the diene elastomer (SBR and BR cutting), the diene elastomer (SBR and BR) are introduced into an internal mixer, 70% filled and having an initial tank temperature of about 90.degree. silica supplemented with a small amount of carbon black, the coupling agent then, after one to two minutes of mixing, the various other ingredients with the exception of the vulcanization system.
• Thermomechanical work (non-productive phase) is then carried out in one step (total mixing time equal to about 5 minutes), until a maximum temperature of "fall” of about 165 ° C. is reached.
• the mixture thus obtained is recovered, cooled and the coating agent (when present) and the vulcanization system (sulfur and sulfenamide accelerator) are added to an external mixer (homogenizer) at 70 ° C. mixing the whole (productive phase) for about 5 to 6 min.
• an external mixer homogenizer
• compositions thus obtained are then calendered either in the form of plates (thickness of 2 to 3 mm) or thin sheets of rubber for the measurement of their physical or mechanical properties, or in the form of profiles that can be used directly, after cutting and / or or assembly to the desired dimensions, for example as semi-finished products for tires, in particular as treads of tires.
• the purpose of this test is to demonstrate the improved properties of tire tread rubber compositions according to the invention, having silica as a reinforcing filler, free of guanidine derivatives, more specifically free of DPG, and free of zinc. , comprising a blocked mercaptosilane of formula (I) (M2) compared to a control composition conventionally comprising commercial blocked mercaptosilane M1, DPG and zinc.
• M2 blocked mercaptosilane of formula (I)
• M1 blocked mercaptosilane of formula (M2)
• SBR / BR blend diene elastomer
• HDS highly dispersible silica
• composition C1 is a control composition containing DPG (1.5 phr) and zinc (1.5 phr of ZnO),
• the composition C2 according to the invention free of DPG and zinc and comprising the mercaptosilane M2
• the blocked mercaptosilane coupling agent of the composition C2 is used at an isomolar silicon level compared to the control composition Cl.
• Tables 1 and 2 give the formulation of the different compositions (Table 1 - rates of the different products expressed in phr or parts by weight per hundred parts elastomer) and their properties after firing (about 40 min at 150 ° C); the vulcanization system is sulfur and sulfenamide.
• composition C2 according to the invention comprising a blocked mercaptosilane of formula (I) and devoid of DPG and zinc, makes it possible to have a reinforcement (MA300 / MA100) comparable to the conventional control composition.
• a blocked mercaptosilane according to the invention is particularly interesting from the point of view of the environment. It makes it possible at the same time to palliate the problems due to the suppression of the zinc.
• silica "ZEOSIL 1,165 MP” from Rhodia in the form of microbeads BET and CTAB: approximately 150-160 m2 / g);
• oleic sunflower oil (Agripure 80" from the company Cargiil);

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• Chemical Kinetics & Catalysis (AREA)
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• 2011
  • 2011-12-16 FR FR1161781A patent/FR2984326B1/fr not_active Expired - Fee Related
• 2012
  • 2012-12-12 US US14/365,484 patent/US20150005449A1/en not_active Abandoned
  • 2012-12-12 WO PCT/EP2012/075239 patent/WO2013087698A1/fr not_active Ceased
  • 2012-12-12 JP JP2014546486A patent/JP6198344B2/ja active Active
  • 2012-12-12 EP EP12799198.2A patent/EP2791147A1/fr not_active Withdrawn
  • 2012-12-12 CN CN201280061813.0A patent/CN104011057B/zh active Active

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