Ethylene-rich diene polymers with polyvinyl pyridine blocks and their use in engine lubricating compositions

Abstract

The present invention relates to a block polymer and an engine lubricating composition comprising the block polymer and a mineral base oil. The invention relates to a block polymer comprising a first block which is a copolymer of 1, 3-butadiene and ethylene, containing more than 90 mol% ethylene units, the molar percentage relative to the total number of constituent repeating units of the first block, and a second block which is a homopolymer of vinylpyridine, the block polymer comprising a first block which is a copolymer of 1, 3-butadiene and ethylene, containing more than 90 mol% ethylene units, the molar percentage relative to the total number of constituent repeating units of the first block.

Description

Technical Field

[0001] The field of the invention is block polymers comprising ethylene-rich diene blocks and polyvinylpyridine blocks, intended for use in engine oils as additives to improve the high-temperature properties of these oils. Background Art

[0002] Engine oils are lubricating compositions containing mineral base oils that are used in engines to minimize energy losses caused by friction in the engine under cold conditions and to maintain a continuous lubricating film on the lubricated parts of the engine under hot conditions. It is important that the viscosity of the lubricating composition decreases as little as possible during operation under hot conditions to avoid disrupting the lubricating film.

[0003] Mineral base oils represent the main component of lubricating compositions as engine oils. The viscosity of mineral base oils decreases with increasing temperature and increases with decreasing temperature. It can be seen that the viscosity of lubricating compositions mainly containing mineral base oils also undergoes changes in their viscosity with temperature.

[0004] In order to reduce the effect of temperature increase on the viscosity of lubricating compositions, it is known to add additives to mineral base oils. These additives are used to thicken the lubricating composition when the temperature increases, thereby partially compensating for the decrease in viscosity under hot conditions. They usually increase the high temperature viscosity to offset the decrease in the viscosity of the mineral base oil. These thickening additives are usually polymers. The two main types of polymers sold for this purpose are polymers with ester functional groups (such as poly (meth) acrylates) and hydrocarbon-based polymers (such as polyisobutylene, copolymers of ethylene and propylene (also known as OCPs), hydrogenated copolymers of dienes and styrene, and hydrogenated polydienes).

[0005] Applicants have discovered that block polymers containing polyvinylpyridine blocks and ethylene-rich copolymer blocks of ethylene and 1,3-butadiene increase the viscosity of engine oils at high temperatures as effectively as OCPs. Summary of the invention

[0006] Thus, a first subject of the invention is a block polymer comprising a first block which is a copolymer of 1,3-butadiene and ethylene and contains more than 90 mol % of ethylene units, the mol % being relative to the total number of constituent recurring units of the first block, and a second block which is a homopolymer of vinylpyridine.

[0007] A second subject of the present invention is a lubricating composition comprising a mineral base oil and a block polymer according to the invention.

[0008] describe:

[0009] Any numerical interval represented by the expression "between a and b" represents a numerical range greater than "a" and less than "b" (i.e., does not include the end values ​​a and b), while any numerical interval represented by the expression "a to b" means a numerical range extending from "a" to "b" (i.e., includes the strict end values ​​a and b).

[0010] Unless otherwise specified, the content of the units in the first block is expressed as a mole percentage relative to all constituent repeating units of the first block.

[0011] The compounds mentioned in this specification may be compounds of fossil origin or may be bio-based compounds. In the case of bio-based compounds, they may be produced partly or completely from biomass, or may be obtained partly or completely from renewable starting materials produced from biomass. Similarly, the compounds mentioned may also originate from the recycling of used materials, i.e. they may be produced partly or completely from a recycling process, or may be obtained from starting materials which themselves are produced from a recycling process.

[0012] The expression "based on" used to define the components of the catalytic system (or catalytic composition) is understood to mean a mixture of these components or a product of the reaction of some or all of these components with one another.

[0013] An essential feature of the block polymer according to the invention is that it comprises two blocks.

[0014] The first constituent block of the block polymer according to the present invention is a copolymer of ethylene and 1,3-butadiene. The constituent monomer units of the first block are those resulting from the copolymerization of ethylene and 1,3-butadiene.

[0015] The ethylene units present in the first block account for more than 90 mol% of the total number of the constituent repeating units of the first block. Preferably, the ethylene units present in the first block account for less than 97 mol% of the total number of the constituent repeating units of the first block. As is well known, the term "ethylene unit" refers to a unit containing a -(CH2-CH2)- subunit.

[0016] As is well known, 1,3-butadiene can be inserted into the growing polymer chain by 1,4 or 1,2 insertion, thereby forming 1,3-butadiene units in 1,4 configuration or 1,3-butadiene units in 1,2 configuration, respectively. When the first block comprises 1,3-butadiene units in 1,4 configuration, the 1,4-trans units preferably account for more than 50% of the units in 1,4 configuration, and more preferably account for more than 80% of the units in 1,4 configuration.

[0017] The first block may also comprise 1,2-cyclohexanediyl subunits, also referred to as 1,2-cyclohexanediyl units of formula (I).

[0018]

[0019] The presence of these cyclic structures in the first block is the result of highly specific insertion of ethylene and 1,3-butadiene during their copolymerization. The mechanism for obtaining this microstructure is described, for example, in Macromolecules 2009, 42, 3774-3779. The content of 1,2-cyclohexanediyl subunits in the first block can vary according to the polymerization conditions for forming the first block, for example, according to the respective contents of ethylene and 1,3-butadiene in the polymerization medium, according to the pressure in the polymerization reactor, according to the catalytic polymerization system, as described, for example, in documents WO 2021 / 023924, WO 2017 / 103543 and WO 2018 / 104669.

[0020] According to a particularly preferred embodiment of the present invention, the first block comprises 1,2-cyclohexanediyl subunits. Preferably, the molar content of 1,2-cyclohexanediyl subunits in the first block is less than 10% of the total number of constituent repeating units of the first block. More preferably, it is from 1% to less than 10% of the total number of constituent repeating units of the first block.

[0021] According to a particularly preferred embodiment of the invention, the first block is a statistical copolymer of ethylene and 1,3-butadiene.

[0022] The essential feature of the second constituent block of the block polymer according to the present invention is that it is a homopolymer of vinyl pyridine. The vinyl pyridine of which the monomer units constitute the second block is a vinyl pyridine as defined in the embodiments of the process according to the present invention. Preferably, the vinyl pyridine is 4-vinyl pyridine, 2-vinyl pyridine or a mixture thereof. More preferably, the vinyl pyridine is 4-vinyl pyridine.

[0023] The molar content of the vinylpyridine units present in the second block may be less than 1% or much greater than 1% of the total number of constituent repeating units of the first block. It is preferably greater than 0.1% of the total number of constituent repeating units of the first block. It is preferably less than 20% of the total number of constituent repeating units of the first block.

[0024] The block polymer according to the invention is preferably a diblock.When the block polymer is a diblock, it generally has the formula AB, wherein A represents the first block and B represents the second block.

[0025] The block polymer according to the present invention can be prepared by a subsequent polymerization process, which comprises the polymerization of a monomer mixture of ethylene and 1,3-butadiene in the presence of a catalyst system to form a first block, followed by homopolymerization of vinyl pyridine to form a second block.

[0026] The catalytic system is based on at least one metallocene of formula (I) and an organomagnesium compound

[0027] P(Cp 1 Cp 2 )Nd(BH4) (1+y) Li y (THF) x (II)

[0028] Cp 1 and Cp 2 is selected from fluorenyl, cyclopentadienyl and indenyl, which groups are substituted or unsubstituted,

[0029] P is the bridge Cp 1 and Cp 2 A group of two groups and represents a group ZR 1 R 2 , Z represents a silicon atom or a carbon atom, R 1 and R 2 are the same or different, each representing an alkyl group containing 1 to 20 carbon atoms, preferably a methyl group,

[0030] y is an integer equal to or greater than 0,

[0031] x is an integer equal to or greater than 0 or a non-integer.

[0032] In formula (II), the neodymium atom is connected to a ligand molecule, which is composed of two groups Cp 1 and Cp 2 The two groups are linked together by a bridge P. Preferably, the symbol P (represented by the term bridge) corresponds to the formula ZR 1 R 2 , Z represents silicon atom, R 1 and R 2 are the same or different and represent an alkyl group containing 1 to 20 carbon atoms. More preferably, the bridge P has the formula SiR 1 R 2 , R 1 and R 2 The same and as defined above. Still more preferably, P corresponds to the formula SiMe2.

[0033] As substituted cyclopentadienyl, fluorenyl and indenyl, there may be mentioned those substituted by an alkyl group having 1 to 6 carbon atoms or by an aryl group having 6 to 12 carbon atoms or a trialkylsilyl group (e.g. SiMe3). 1 and Cp 2When substituted, they are preferably substituted by methyl, butyl (especially tert-butyl) or trimethylsilyl. These groups are preferred regardless of the embodiment of the invention. The choice of group also depends on the availability of the corresponding molecules, which are substituted cyclopentadienes, fluorenes and indene, because the molecules are commercially available or can be easily synthesized.

[0034] As substituted cyclopentadienyl groups, mention may be made of those substituted at position 2 (or 5) or at position 3 (or 4), in particular those substituted at position 2, more particularly tetramethylcyclopentadienyl. Position 2 (or 5) denotes the position of the carbon atom adjacent to the carbon atom to which the bridge P is attached, as shown in the figure below. As a reminder, substitution at position 2 or 5 is also referred to as substitution at the alpha position relative to the bridge.

[0035]

[0036] As substituted fluorenyl groups, mention may be made of those substituted with an alkyl group having 1 to 6 carbon atoms or with an aryl group having 6 to 12 carbon atoms. The choice of the group also depends on the availability of the corresponding molecule (i.e., substituted fluorene), since the corresponding molecule is commercially available or can be easily synthesized.

[0037] As substituted fluorenyl groups, mention may be made in particular of those substituted at positions 2, 7, 3 or 6, more particularly 2,7-di(tert-butyl)fluorenyl and 3,6-di(tert-butyl)fluorenyl. As shown in the figure below, positions 2, 3, 6 and 7 represent the positions of the carbon atoms of the ring, respectively, and position 9 corresponds to the carbon atom to which the bridge P is attached.

[0038]

[0039] As substituted indenyl groups, mention may in particular be made of those substituted in position 2, more particularly 2-methylindenyl or 2-phenylindenyl. Position 2 denotes the position of the carbon atom adjacent to the carbon atom to which the bridge P is attached, as shown in the figure below.

[0040]

[0041] According to one embodiment of the present invention, Cp 1 and Cp 2 one represents a cyclopentadienyl group and the other represents a fluorenyl group. This embodiment is particularly suitable for preparing a first block which does not contain any 1,2-cyclohexanediyl subunits of formula (I).

[0042] According to another embodiment of the present invention, Cp 1 and Cp 2 are the same and are selected from substituted fluorenyl and fluorenyl. Advantageously, Cp 1 and Cp 2Each represents a substituted fluorenyl or fluorenyl, preferably a fluorenyl. The fluorenyl group has the formula C 13 H8. Preferably, the metallocene has the formula (IIa), (IIb), (IIc), (IId) or (IIe), wherein the symbol Flu represents the formula C 13 The fluorenyl group of H8.

[0043] [{Me2SiFlu2Nd(μ-BH4)2Li(THF)}2] (IIa)

[0044] [Me2SiFlu2Nd(μ-BH4)2Li(THF)] (IIb)

[0045] [Me2SiFlu2Nd(μ-BH4)(THF)] (IIc)

[0046] [{Me2SiFlu2Nd(μ-BH4)(THF)}2] (IId)

[0047] [Me2SiFlu2Nd(μ-BH4)] (IIe)

[0048] The organomagnesium compound used as a cocatalyst in the catalytic system is a compound having at least one C-Mg bond. As organomagnesium compounds, mention may be made of diorganomagnesium compounds, in particular dialkylmagnesium compounds, and organomagnesium halides, in particular alkylmagnesium halides. The diorganomagnesium compound generally has the formula MgR 3 R 4 , where R 3 and R 4 The term "carbonyl group" refers to a group containing one or more carbon atoms. Preferably, R 3 and R 4 More preferably, R 3 and R 4 The organomagnesium compound is preferably a diorganomagnesium compound or an organomagnesium halide, advantageously a dialkylmagnesium compound, still more preferably butylethylmagnesium or butyloctylmagnesium, even more preferably butyloctylmagnesium.

[0049] The catalytic system can be conventionally prepared by methods similar to those described in patent applications WO 2007 / 054224 A2 or WO 2007 / 054223 A2. For example, the organomagnesium compound and the metallocene are reacted in a hydrocarbon-based solvent, usually at a temperature of 20° C. to 80° C. for a period of time between 5 and 60 minutes. The catalytic system is usually prepared in an aliphatic hydrocarbon-based solvent (e.g. methylcyclohexane) or an aromatic hydrocarbon-based solvent (e.g. toluene). Usually, after its synthesis, the catalytic system is used as is in the synthesis process of the block polymer.

[0050] Alternatively, the catalytic system can be prepared by a method similar to that described in patent application WO 2017 / 093654 A1 or patent application WO2018 / 020122 A1. According to this alternative, the catalytic system also comprises a preformed monomer selected from 1,3-diene, ethylene or a mixture of ethylene and 1,3-diene, in which case the catalytic system is based at least on a metallocene, an organomagnesium compound and a preformed monomer. For example, the organomagnesium compound and the metallocene are reacted in a hydrocarbon-based solvent, usually at a temperature of 20°C to 80°C for 10 to 20 minutes to obtain a first reaction product, and then the preformed monomer (selected from 1,3-diene, ethylene or a mixture of ethylene and 1,3-diene) is reacted with the first reaction product at a temperature of 40°C to 90°C for 1 to 12 hours. The preformed monomer is preferably 1,3-butadiene or a mixture of ethylene and 1,3-butadiene. The catalytic system thus obtained can be used immediately in the method according to the invention, or it can also be stored under an inert atmosphere before the polymerization method for preparing a block polymer.

[0051] The metallocene for preparing the catalyst system can be in the form of crystalline powder or non-crystalline powder, or in the form of single crystal.Metallocene can be in monomer or dimer form, and these forms depend on the preparation method of metallocene, as described in patent application WO 2007 / 054224 A2 or WO 2007 / 054223A2 for example.Metallocene can be prepared conventionally by the method similar to that described in patent application WO2007 / 054224A2 or WO 2007 / 054223 A2, particularly under inert and anhydrous conditions, the alkali metal salt of ligand and rare earth metal borohydride are reacted in suitable solvent (for example, ether such as diethyl ether or tetrahydrofuran, or any other solvent known to persons skilled in the art).After the reaction, by technology known to persons skilled in the art, for example, filtering or precipitating from the second solvent, metallocene is separated from byproduct of reaction.Finally, dry and separate metallocene in solid form.

[0052] As with any synthesis carried out in the presence of an organometallic compound, the synthesis of metallocenes and catalytic systems is carried out under anhydrous conditions in an inert atmosphere. Typically, the reaction is carried out starting from anhydrous solvents and compounds under anhydrous nitrogen or argon.

[0053] The skilled person also adjusts the polymerization conditions and the concentration of each reagent (components of the catalyst system, monomers) according to the equipment (tools, reactors) used to carry out the polymerization. As known to the skilled person, the polymerization and handling of monomers, catalyst systems and copolymerization solvents are carried out under anhydrous conditions and an inert atmosphere. The polymerization solvent is usually an aliphatic or aromatic hydrocarbon-based solvent.

[0054] The polymerization is preferably carried out continuously or discontinuously in a reactor (advantageously a stirred reactor) in solution. The polymerization solvent may be an aromatic or aliphatic hydrocarbon-based solvent. As examples of polymerization solvents, toluene and methylcyclohexane may be mentioned. Advantageously, the polymerization is carried out in a solution of a hydrocarbon-based solvent (e.g. methylcyclohexane).

[0055] Those skilled in the art adjust the polymerization conditions, such as polymerization temperature, concentration of each reagent and pressure in the reactor, according to the composition of the monomer mixture, the polymerization reactor and the desired microstructure and macrostructure of the copolymer chain.

[0056] The first block is synthesized by copolymerization of ethylene and 1,3-butadiene. Ethylene and 1,3-butadiene can be introduced into a reactor containing a polymerization solvent and a catalyst system, or conversely, the catalyst system can be introduced into a reactor containing a polymerization solvent and the monomers ethylene and 1,3-butadiene.

[0057] The polymerization temperature generally varies within the range of 30° C. to 160° C., preferably 30° C. to 120° C. During the synthesis of the first block, the temperature of the reaction medium is advantageously kept constant during the polymerization and the total pressure in the reactor is also advantageously kept constant. Preferably, the monomer mixture of ethylene and 1,3-butadiene is polymerized under a constant ethylene pressure.

[0058] In order to achieve the desired macrostructure of the first block, the skilled person adjusts the polymerization conditions, in particular the molar ratio of the organomagnesium reagent to the metal Nd constituting the metallocene. The molar ratio can reach a value of 100, and it is known that a molar ratio of less than 10 is more favorable for obtaining polymers with high molar mass.

[0059] During the synthesis of the first block, ethylene and 1,3-butadiene may be added continuously to the polymerization reactor, in which case the polymerization reactor is a feed reactor.This embodiment is most particularly suitable for the synthesis of the first block as a statistical copolymer.

[0060] The synthesis of the first block is completed by cutting off the supply of monomers, in particular by reducing the pressure of the reactor, preferably to about 3 bar. At the end of the synthesis of the first block, the reaction medium is degassed, preferably by multiple degassing with an inert gas, such as nitrogen. The preparation of the block polymer is continued by the synthesis of the second block by subsequent homopolymerization of vinylpyridine in the degassed reaction medium.

[0061] Vinyl pyridine can be a mixture of vinyl pyridine or one of the isomers of vinyl pyridine, the isomerism of which is determined by the substituted carbon of the aromatic ring of pyridine. Preferably, vinyl pyridine is 4-vinyl pyridine, 2-vinyl pyridine or a mixture thereof. More preferably, vinyl pyridine is 4-vinyl pyridine. When vinyl pyridine is packaged in the presence of a stabilizer, as is the case with most commercially available vinyl pyridines, it is usually used after removing the stabilizer, which can be carried out in a known manner by distillation or by contacting with aluminum oxide (e.g., by treating on an aluminum oxide column).

[0062] Vinyl pyridine can be added to the reactor in pure form, or diluted in a hydrocarbon solvent, preferably an aliphatic hydrocarbon solvent, such as methylcyclohexane. Pure or diluted vinyl pyridine is introduced into a degassed reaction medium. The amount of vinyl pyridine introduced into the reaction mixture polymerized in the form of the second block is adjusted by a person skilled in the art according to the desired content of vinyl pyridine in the form of a block polymer. It can vary over a wide range, particularly 0.01 g to 25 g / 100 g of the first block formed, more particularly 2 g to 25 g / 100 g of the block formed. The homopolymerization of vinyl pyridine is preferably carried out at the same temperature as the temperature of the synthesis of the first block. The polymerization temperature for the synthesis of the second block is generally varied in the range of 30°C to 160°C, preferably 30°C to 120°C. Chromatographic analysis can generally be performed after the synthesis of the second block to monitor the consumption of vinyl pyridine. When the second block reaches the desired number average molar mass or when the conversion rate of the reaction of the polymerized vinyl pyridine reaches the desired conversion rate (e.g., 100%), the synthesis of the second block is completed.

[0063] The synthesis of the second block can be stopped by cooling the polymerization medium or by adding an alcohol, preferably an alcohol containing 1 to 3 carbon atoms, such as ethanol. The block polymer can be recovered according to conventional techniques known to those skilled in the art, for example by precipitation, by evaporation of the solvent under reduced pressure or by stripping.

[0064] Preferably, the block polymers according to the invention which can be prepared by the process according to the invention are diblocks.

[0065] The block polymers may be added to the mineral base oil to form the lubricating composition, which is another subject of the present invention.The constituent block polymers of the lubricating composition may be a mixture of block polymers as defined previously, which block polymers differ from one another in their respective composition.

[0066] As suitable mineral base oils, Group I base oils, Group II base oils and Group III base oils, and mixtures thereof, may be mentioned. As is well known, Groups I to III are defined according to the American Petroleum Institute (API) in its publication "API N° 1509 Engine Oil Licensing and Certification System, Appendix E, 14th Edition" (December 1996). Mineral base oils are generally obtained by atmospheric and vacuum distillation of crude oil, optionally followed by refining operations.

[0067] The amount of block polymer added to the mineral base oil is adjusted by the skilled person according to the nature of the mineral base oil, according to the characteristics of the block polymer and, of course, according to the use of the lubricating composition. The weight content of the block polymer or the mixture of block polymers in the lubricating composition may be up to 5% by weight of the lubricating composition, for example from 0.01% to 5% by weight of the lubricating composition, preferably from 0.05% to 2% by weight of the lubricating composition. Preferably, the mineral base oil is a Group I base oil.

[0068] The mixture formed from the base oil and the block polymer constitutes a lubricating composition which may also contain other additives conventionally used in engine oils, such as detergents and dispersants, antioxidants, compounds having an anti-rust, anti-foam and anti-icing effect.

[0069] The lubricating composition according to the present invention has high temperature thickening properties similar to engine oils containing conventionally used viscosity improvers such as copolymers of ethylene and propylene. DETAILED DESCRIPTION

[0070] In summary, the present invention is advantageously implemented according to any one of the following embodiments 1 to 14:

[0071] Embodiment 1: A block polymer comprising a first block and a second block, wherein the first block is a copolymer of 1,3-butadiene and ethylene, containing more than 90 mol % of ethylene units, the molar percentage being relative to the total number of constituent repeating units of the first block, and the second block is a homopolymer of vinylpyridine.

[0072] Embodiment 2: The block polymer of Embodiment 1, wherein the first block is a statistical copolymer of ethylene and 1,3-butadiene.

[0073] Embodiment 3: The block polymer according to any one of Embodiments 1 to 2, wherein the block polymer is a diblock.

[0074] Embodiment 4: The block polymer according to any one of Embodiments 1 to 3, wherein the ethylene units present in the first block account for less than 97 mol% of the total number of constituent repeating units of the first block.

[0075] Embodiment 5: The block polymer of any one of Embodiments 1 to 4, wherein the first block comprises 1,2-cyclohexanediyl subunits.

[0076] Embodiment 6: The block polymer according to Embodiment 5, wherein the molar content of the 1,2-cyclohexanediyl subunit in the first block is less than 10% of the total number of constituent repeating units of the first block.

[0077] Embodiment 7: The block polymer according to Embodiment 5 or 6, wherein the molar content of the 1,2-cyclohexanediyl subunit in the first block is 1% to less than 10% of the total number of constituent repeating units of the first block.

[0078] Embodiment 8: The block polymer according to any one of Embodiments 1 to 7, wherein the vinyl pyridine is 4-vinyl pyridine, 2-vinyl pyridine, or a mixture thereof.

[0079] Embodiment 9: The block polymer according to any one of Embodiments 1 to 8, wherein the molar content of the vinylpyridine units present in the second block is greater than 0.1% of the total number of constituent repeating units of the first block.

[0080] Embodiment 10: The block polymer according to any one of Embodiments 1 to 9, wherein the molar content of the vinylpyridine units in the second block is less than 20% of the total number of constituent repeating units of the first block.

[0081] Embodiment 11: A lubricating composition comprising a mineral base oil and a block polymer as defined in any one of embodiments 1 to 10.

[0082] Embodiment 12: The lubricating composition according to Embodiment 11, wherein the weight content of the block polymer is 0.01 wt % to 5 wt % of the lubricating composition.

[0083] Embodiment 13: The lubricating composition according to Embodiment 11 or 12, wherein the weight content of the block polymer is 0.05 wt % to 2 wt % of the lubricating composition.

[0084] Embodiment 14: The lubricating composition of any one of Embodiments 11 to 13, wherein the mineral base oil is a Group I base oil.

[0085] Example

[0086] Determination of polymer microstructure:

[0087] High-resolution NMR spectra of the polymers were performed on a Bruker 600 Avance III HD spectrometer equipped with a CP2.1 BBO 600S3 proton probe, operating at 600 MHz. Acquisition was performed at 368 K. Ortho-dichlorobenzene (o-DCB) was used as solvent. Proton NMR ( 1 H NMR) analysis. Chemical shifts were determined relative to the proton signal of o-dichlorobenzene, which was set at 7.2 ppm. The following sequence was used for 2D analysis: HSQC: pulse program; hsqcetgpsi2 "HSQC with gradient"; SW1: 180 ppm ( 13 C); SW2: 12ppm( 1 H); d1: 10 sec; 90° “hard” pulse 1 HP1 = 13 μs and 16 W and 13 C P2 = 26 μs and 84 W; gradient: SMSQ10.100.

[0088] According to Llauro et al., Macromolecules, 2001, 34, 6304-6311, the attribution of the signal characteristics of the first block is defined in the literature.

[0089] The attribution of the signal characteristics of the second block is defined as follows: 1 H=8.29ppm(=CH-N=CH-); δ 1 H=6.34ppm(=CH-C(CH2)=CH-); δ 13 C=150ppm(=CH-N=CH-); δ 13 C=6.34ppm (=CH-C(CH2)=CH-).

[0090] DOSY NMR (Diffusion Ordered Spectroscopy) Analysis of Block Polymers:

[0091] The DOSY experiment is an NMR method that allows the analysis of complex mixtures and the detection of trace amounts of substances. The purpose of this experiment is to show that the block polymer represents the majority of the sample and that the homopolymer present is very low or absent.

[0092] DOSY NMR analysis makes it possible to separate the substances present, in particular polymer matrices, by analyzing their solution diffusion coefficients. The principle of the technique is as follows:

[0093] The DOSY experiment consists of recording the proton spectrum while varying the force G of the applied gradient and thus the diffusion force. A linear increase in the strength of the gradient causes an exponential decrease in the NMR signal intensity. The DOSY experiment produces a two-dimensional graph. After Fourier transformation processing, the second dimension F2 of DOSY corresponds to 1 H dimensions. The first dimension F1 corresponds to the decrease of the NMR signal as the applied gradient force changes. After processing the dimension F2, the diffusion coefficient is extracted using equation (1) to obtain the DOSY map.

[0094] I=I0.exp(-Dγ 2 G 2 δ 2 (Δ-δ / 3)) (1)

[0095] where I is the observed intensity, I0 is the reference intensity, D is the diffusion coefficient, γ is the observed nuclear gyromagnetic ratio, G is the force of the gradient, δ is the length of the gradient, and Δ is the diffusion time.

[0096] If the two substrates have the same diffusion coefficient, this means that the two substrates have the same hydrodynamic radius and are therefore grafted. On the other hand, if the two substrates have two different diffusion coefficients, this means that they are free relative to each other.

[0097] The equation describing the diffusion coefficient is as follows:

[0098]

[0099] where k B is the Boltzmann constant, T is the temperature, η is the viscosity of the liquid in which the molecule resides, and rs is the hydrodynamic radius of the molecule (in this case the matrix or polymer).

[0100] The experiment was conducted on a poly(butadiene)-b-poly(ethylene-co-butadiene) sample synthesized according to the method of the present invention.

[0101] and 1 H NMR spectra are compared to two 1D spectra recorded by diffusion filtering. 1 H NMR spectroscopy, one with the magnetic field gradient set to 90% of the maximum power of the gradient amplifier and the other to 1% of this value, allows observation of the ratio of signal loss due to spatial diffusion of the molecules and magnetization relaxation. Signal loss due to diffusion is then attributed to “small molecules” (reagents, antioxidants, solvents, etc.) that are not grafted onto the polymer matrix.

[0102] Determination of polymer macrostructure :

[0103] Size exclusion chromatography is used. It should be recalled that SEC can separate macromolecules in solution according to their size using a chromatographic column filled with a porous gel. The macromolecules are separated according to their hydrodynamic volume, with the largest eluting first. Although not an absolute method, SEC can provide insight into the distribution of polymer molar masses. Various number average molar masses (Mn) and weight average molar masses (Mw) can be determined from commercial standards, and the degree of dispersion Can be calculated by "mole" calibration.

[0104] Preparation of polymer: There is no special treatment for the polymer sample before analysis. It is simply dissolved in 1,2,4-trichlorobenzene containing 300 ppm BHT (butylated hydroxytoluene) at a concentration of about 1 g / L. The solution is stirred at 160°C for 2 hours before injection, and the chromatographic device used is equipped with an online filtration system.

[0105] SEC analysis: High temperature size exclusion chromatography or HT-SEC was used. The apparatus used was a GPC-IR chromatograph equipped with an IR-6 infrared detector from Polymer Char. The vibration bands of CH2 and CH3 groups were detected by the IR detector. A set of 3 "mixed BN-LS" commercial reference columns from Polymer Char were used. The elution solvent was 1,2,4-trichlorobenzene containing 300 ppm BHT, the flow rate was 1 ml / min, the system temperature was 160°C, and the analysis time was 90 minutes (min).

[0106] The injection volume of the polymer sample solution was 200 microliters. The software used for the chromatographic data was the GPC-one system from Polymer Char.

[0107] The average molar mass was determined from a calibration curve generated from commercially available polystyrene standards using the PSS Ready Cal-Kit.

[0108] Determination of crystallinity, melting point and glass transition temperature of polymers:

[0109] Crystallinity, melting point and glass transition temperature were determined by differential scanning calorimetry (DSC). The analysis was performed on a Netzsch DSC 214Polyma DSC device calibrated with indium. The temperature range of the device was -150°C to 700°C. The computer integrated into the DSC controlled the device using Netzsch's Proteus software. The sample was weighed (about 10 mg) and sealed in a 40 microliter aluminum crucible. The crucible was pierced with a fine needle before the measurement. The sample was analyzed at 40 ml / min under helium according to a dynamic method consisting of 7 temperature steps:

[0110] Step 1: Cool from 25°C to -150°C at a rate of 50°C / min; Step 2: Keep constant temperature at -150°C for 5 minutes; Step 3: Heat from -150°C to 200°C at a rate of 20°C / min; Step 4: Keep constant temperature at 200°C for 5 minutes; Step 5: Cool from 200°C to -150°C at a rate of 20°C / min; Step 6: Keep constant temperature at -150°C for 5 minutes; Step 7: Heat from -150°C to 200°C at a rate of 20°C / min.

[0111] The first four steps allow the thermal history of the sample to be eliminated. The measurement of the glass transition temperature (Tg) and the melting point (Tm) is performed in the 7th step. The 7th step is also retained in order to obtain information about the crystallization of the sample and determine the degree of crystallinity.

[0112] Tg and Tm values ​​were determined by data reprocessing using Netzsch's Proteus software. Crystallinity was determined using standard ISO 11357-3:2011, measuring the melting and crystallization temperatures and enthalpies of the polymers used by differential scanning calorimetry (DSC). The reference enthalpy of polyethylene is 293 J / g (source: B. Wunderlich, Thermal Analysis, Academic Press, 1990, 281).

[0113] Polymer Synthesis:

[0114] All reagents were obtained commercially except the metallocene [{Me2SiFlu2Nd(μ-BH4)2Li(THF)}] which was prepared according to the procedure described in patent application WO 2007 / 054224.

[0115] Butyloctylmagnesium BOMAG (20 wt% in heptane, C = 0.88 mol.l -1 ) was obtained from Lanxess and stored in metal cylinders under an inert atmosphere. Ethylene grade N35 was obtained from Air Liquide and used without prior purification. 1,3-Butadiene was purified by passing through an alumina protection tube. Methylcyclohexane solvent from BioSolve was dried and purified on an alumina column in a solvent purifier from mBraun and used in an inert atmosphere. All reactions were performed in an inert atmosphere.

[0116] Purification of 4-vinylpyridine:

[0117] Purified 4-vinylpyridine was prepared according to the following procedure:

[0118] 100 ml of 4-vinylpyridine (Sigma-Aldrich, 95% purity, containing 100 ppm of hydroquinone) were placed in a steinie bottle. 30 g of alumina were introduced into the bottle. The bottle was then capped and stirred in the dark at ambient temperature (23° C.) for 60 minutes.

[0119] Preparation of a solution of 4-vinylpyridine in methylcyclohexane:

[0120] Methylcyclohexane (MCH) was purified by passing through an alumina guard tube before being used to prepare solutions.

[0121] A first solution of 4-vinylpyridine in MCH (solution A) was prepared as follows: 0.26 ml of purified 4-vinylpyridine was introduced under nitrogen pressure into 20 ml of MCH contained in a 250 ml Steinie bottle with a cap.

[0122] A second solution of 4-vinylpyridine in MCH (solution B) was prepared as follows: 0.65 ml of purified 4-vinylpyridine was introduced under nitrogen pressure into 20 ml of MCH contained in a 250 ml Steinie bottle with a cap.

[0123] The bottles containing solutions A and B respectively were pressurized under 3 bar nitrogen.

[0124] Example 1: Preparation of block polymer according to the present invention:

[0125] 30.4 mg (47.5 μmol) of metallocene Me2Si(C 13 H8)2Nd(BH4)2Li. THF was weighed in a 250 mL Steinie bottle in a glove box.

[0126] 296 ml of MCH were introduced into a 750 ml Steinie bottle. The bottle was placed under an inert atmosphere by nitrogen bubbling for 10 minutes. 4.57 ml (499 μmol, Mg / Nd=10.5) of a 0.11 mol / l solution of butyloctyl magnesium in MCH were introduced into the 750 ml bottle containing MCH to form solution C.

[0127] A mixture of ethylene monomer and 1,3-butadiene containing 92 mol % of ethylene and 8 mol % of 1,3-butadiene was also prepared by first injecting 0.48 bar of 1,3-butadiene into the ballast and then injecting 5.52 bar of ethylene to make up the gaseous mixture. A mixture containing 92 mol % of ethylene and 8 mol % of 1,3-butadiene at an absolute pressure of 6 bar (ethylene / butadiene mixture: 92 / 8) was obtained.

[0128] The ballast is connected to the polymerization reactor.

[0129] About one third of solution C was transferred via cannula to the 250 ml bottle containing the metallocene to activate the metallocene and form the catalyst system.

[0130] Half of solution C was introduced into a stirred (400 rpm) reactor and brought to 77° C., wherein the reactor was previously placed under an inert atmosphere. The contents of the 250 ml bottle containing the catalyst system were introduced into the reactor. The remaining solution C was then transferred to the reactor. The reactor was degassed under vacuum until bubbles formed and then pressurized to 3 bar with an ethylene / butadiene mixture (92 / 8).

[0131] When the ballast pressure registered a pressure drop corresponding to 12.7 grams of monomer, the reactor was degassed using 3 vent / nitrogen cycles.

[0132] Solution A containing 4-vinylpyridine was introduced into the reactor. Stirring was maintained for 1 hour, then the heating was turned off and stirring was stopped.

[0133] The reactor was disassembled, the polymerization medium was deactivated with 2 ml of ethanol to stop the polymerization reaction, and then transferred to an aluminum pan and dried in an oven under vacuum at 60° C. for 24 hours. The recovered polymer was white and opaque.

[0134] After 24 hours, the dried polymer was recovered for analysis.The block polymer is a diblock comprising a first block of a statistical copolymer of ethylene and 1,3-butadiene and a second block of poly(4-vinylpyridine).

[0135] The first block of the block polymer contains 91 mol% of ethylene units, 6 mol% of 1,2-cyclohexanediyl units, 1 mol% of 1,2-configuration 1,3-butadiene units and 2 mol% of 1,4-configuration (mainly 1,4-trans) 1,3-butadiene units. The second block of poly (4-vinyl pyridine) accounts for 0.5 mol% of the total number of ethylene units, 1,2-cyclohexanediyl units, 1,2-configuration 1,3-butadiene units and 1,4-trans-configuration 1,3-butadiene units. DOSY NMR analysis shows a diffusion coefficient corresponding to the block polymer EBR-b-PVP. By HT-SEC analysis, the number average molar mass of the block polymer is 12 500 g / mol and the dispersion index is 1.88.

[0136] Example 2: Preparation of block polymer according to the present invention:

[0137] The block polymer was prepared according to the same procedure as Example 1, with the only difference being that solution B was used instead of solution A.

[0138] The first block of the block polymer contains 92 mol% of ethylene units, 5 mol% of 1,2-cyclohexanediyl units, 1 mol% of 1,2-configuration 1,3-butadiene units, and 2 mol% of 1,4-configuration (mainly 1,4-trans) 1,3-butadiene units. The molar content of the 4-vinylpyridine unit is 1.4 mol% of the total of the ethylene units, 1,2-cyclohexanediyl units, 1,2-configuration 1,3-butadiene units, and 1,4-configuration (mainly 1,4-trans) 1,3-butadiene units.

[0139] According to HT-SEC analysis, the block polymer had a number average molar mass of 12 000 g / mol and a dispersion index of 1.9.

[0140] The weighed mass of block polymer made it possible to determine the average catalytic activity of the catalytic system, expressed as kilograms of polymer synthesized per mole of neodymium metal per hour (kg / mol.h). The catalytic activity was 214 kg.mol / h.

[0141] The Tg of the polyvinylpyridine block was 160° C. The crystallinity of the block polymer was 36.8%.

[0142] Example 3: Preparation of statistical ethylene-1,3-butadiene copolymer not according to the present invention:

[0143] The polymer was prepared following the same procedure as in Examples 1 and 2, except that no vinyl pyridine solution was added after the copolymerization of ethylene and 1,3-butadiene. When the pressure of the ballast registered a pressure drop corresponding to 12.7 g of monomer, the reactor was degassed using 3 vent / nitrogen cycles and the mixture was terminated with 2 ml of ethanol.

[0144] The polymer solution was then dried in a vacuum oven at 60°C under a nitrogen purge for 24 hours.

[0145] The weighed mass of the copolymer made it possible to determine the average catalytic activity of the catalytic system, expressed as kilograms of polymer synthesized per mole of neodymium metal per hour (kg / mol.h). The catalytic activity was 191 kg / mol.h.

[0146] HT-SEC analysis of the copolymer showed a unimodal molecular distribution with a Mn of 11 800 g / mol and a dispersity of 1.87.

[0147] The copolymer of ethylene and 1,3-butadiene contains 91 mol% of ethylene units, 6 mol% of 1,2-cyclohexanediyl units, 1 mol% of 1,3-butadiene units having a 1,2 configuration, and 2 mol% of 1,3-butadiene units having a 1,4 configuration.

[0148] The Tg of the copolymer of ethylene and 1,3-butadiene was -21° C. When passing through the same transition temperature (-21° C.) as in Examples 1 and 2, the DSC thermogram showed an endothermic phenomenon.

[0149] Example 3 is a comparative example since it corresponds to the synthesis of the first block of Examples 1 and 2.

[0150] Preparation of a lubricating composition comprising base oil 600:

[0151] Lubricating compositions C0, C1 and C2 were prepared according to the following procedure:

[0152] 1 g of polymer was introduced into a TM 600 Group I mineral base oil in a 250 ml steinie bottle. The steinie bottle is capped and stirred in a thermostatically controlled bath at 90°C for 12 hours. The viscosity of the resulting mixture is measured at 100°C. For composition C1, the polymer is the block polymer of Example 1; for composition C2, the polymer is the block polymer of Example 2; for composition C0, the polymer is an OCP sold by Lubrizol under the reference number 7077, which is a copolymer of ethylene and propylene containing about 50 mol% ethylene. Composition C0 comprising base oil 600 is a reference composition because it comprises a copolymer not according to the invention, namely copolymer 7077 from Lubrizol, which is an additive commonly used in engine oils as a high temperature (100°C) thickener. Base oil Core sold by Exxon TM 600 is a Group I mineral base oil, commonly used as the base oil for engine oil.

[0153] The kinematic viscosity of the lubricating composition at 100° C. is measured according to standard ASTM 445-21. The viscosity results relative to a control, based on 100, are given in Table 1. The control consists of the same base oil used in the lubricating composition.

[0154] Table 1

[0155] Lubricating composition T1 C0 C1 C2 Base oil 600 600 600 600 polymer - OCP Example 1 Example 2 Viscosity at 100°C 100 103 108 109

[0156] It is observed that the viscosity of the lubricating compositions (C1; C2) comprising the block polymers according to the invention at 100°C is greater than the viscosity of the base oil (T1) they contain. The viscosity of the lubricating compositions C1 and C2 is higher than the viscosity of the reference composition C0. This result is obtained even though the number average molar mass of the copolymers according to the invention is much lower than that of the OCP copolymers. Surprisingly, the block polymers according to the invention have proven to be as effective as OCP copolymers as high temperature thickeners for mineral base oils.

Claims

1. A block polymer comprising a first block and a second block, wherein the first block is a copolymer of 1,3-butadiene and ethylene and contains more than 90 mol % of ethylene units, the molar percentage being relative to the total number of constituent repeating units of the first block, and the second block is a homopolymer of vinylpyridine.

2. The block polymer according to claim 1, wherein The first block is a statistical copolymer of ethylene and 1,3-butadiene.

3. The block polymer according to any one of claims 1 to 2, which is a diblock.

4. The block polymer according to any one of claims 1 to 3, wherein The ethylene units present in the first block account for less than 97 mol% of the total number of constituent repeating units of the first block.

5. The block polymer according to any one of claims 1 to 4, wherein The first block comprises 1,2-cyclohexanediyl subunits.

6. The block polymer according to claim 5, wherein The molar content of the 1,2-cyclohexanediyl subunit in the first block is less than 10% of the total number of constituent repeating units of the first block.

7. The block polymer according to claim 5 or 6, wherein The molar content of the 1,2-cyclohexanediyl subunit in the first block is 1% to less than 10% of the total number of constituent repeating units of the first block.

8. The block polymer according to any one of claims 1 to 7, wherein The vinyl pyridine is 4-vinyl pyridine, 2-vinyl pyridine or a mixture thereof.

9. The block polymer according to any one of claims 1 to 8, wherein The vinylpyridine units present in the second block are present in an amount of more than 0.1% by mole of the total number of constituent repeating units of the first block.

10. The block polymer according to any one of claims 1 to 9, wherein The molar content of the vinylpyridine units in the second block is less than 20% of the total number of constituent repeating units of the first block.

11. Lubricating composition comprising a mineral base oil and a block polymer as defined in any one of claims 1 to 10.

12. The lubricating composition according to claim 11, wherein The mineral base oil is a Group I base oil.

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