Method for preparing neodymium alkyl phosphate solutions

Abstract

The present invention relates to a method for producing a neodymium(III) alkyl phosphate solution, the method comprising the following steps: (a) reacting a neodymium(III) compound with an organic phosphoric acid in a solvent in the presence of an accelerator, thereby obtaining a neodymium(III) alkyl phosphate solution, (b) adding an antigelling agent to the neodymium(III) alkyl phosphate solution obtained in step (a), and (c) removing water formed and / or added during step (a) from the obtained neodymium(III) alkyl phosphate solution, thereby obtaining a solution containing neodymium(III) alkyl phosphate. The present invention also relates to the neodymium(III) alkyl phosphate solution obtained by the above method and to the use of this solution as a catalyst precursor for diene polymerization.

Description

[Technical Field]

[0001] The present invention relates to a process for preparing neodymium alkyl phosphate solutions in non-polar organic solvents. The solutions obtainable by the claimed process are particularly useful as starting materials for the preparation of catalysts for diene polymerization. [Background technology]

[0002] Neodymium complexes containing alkyl phosphates are well-known catalysts for the cis-1,4 polymerization of conjugated dienes, including in particular the homopolymerization of 1,3-butadiene. Patent Document 1 describes a process for preparing gel-free hydrocarbon solutions containing lanthanide rare earth compounds by dissolving or synthesizing the lanthanide compounds in an inert hydrocarbon solvent with a Lewis acid selected from the group consisting of transition metal halides, organometallic halides whose metals belong to Groups 2, 12, 13, and 14 of the periodic system, and halides of elements in Groups 2, 12, 13, 14, and 15 of the periodic system, in an amount sufficient to prevent the formation of a highly viscous solution. A hydrocarbon-soluble Lewis acid, such as tin(IV) tetrachloride, is most preferred.

[0003] Patent Document 2 describes a method for preparing a solution of a rare earth organophosphate in an organic solvent, comprising reacting a rare earth compound selected from the group consisting of oxides, hydroxides, carbonates, and hydroxycarbonates of rare earth metals with an organophosphoric acid in the presence of a solvent. The reaction is carried out in the presence of a compound selected from the group consisting of nitric acid, hydrochloric acid, acetic acid, formic acid, propionic acid, and rare earth salts of said acids. A preferred embodiment of the method involves the use of neodymium as the rare earth metal, a phosphoric acid diester, and an alicyclic solvent. Another embodiment of the method disclosed in Patent Document 2 is directed to the use of water in a molar ratio to the rare earth metal of at least 25, preferably at least 50.

[0004] Patent Document 3 discloses a method for producing a rare earth salt of dialkyl phosphate, which comprises reacting a rare earth oxide or hydroxide with a dialkyl phosphate having a purity of 97% or more in a non-polar solvent in the presence of at least one compound selected from hydrohalic acid, phosphorous acid, and a rare earth halide as a catalyst. A preferred embodiment of the method includes the use of neodymium as the rare earth metal, bis(2-ethylhexyl)phosphate, and hydrochloric acid. Among the preferred viscosity reducers, tin(IV) tetrachloride was explicitly mentioned.

[0005] Rare earth metal alkyl phosphate solutions, including neodymium alkyl phosphate solutions, obtained by prior art methods exhibit high viscosity. This characteristic results, at least in part, from gel formation in the reaction of the rare earth metal precursor with the organophosphorus compound. Such high viscosity must be reduced by adding alcohol, carboxylic acid, or phosphoric acid before the solution is used to prepare a catalyst system for diene polymerization. However, such additional additives constitute undesirable impurities in the final rubber product, so there is a need to provide a neodymium alkyl phosphate solution with an acceptable viscosity level.

[0006] In another approach, Patent Document 4 applies high shear rates to a process for the synthesis of rare earth organophosphate solutions, resulting in a product that is free of residual rare earth precursors and has a consistency suitable for processing in equipment suitable for low viscosity products. This process is carried out over a period of 200 s -1 The method includes dispersing a rare earth oxide in a two-phase medium containing at least one organic solvent, water, an organic phosphoric acid, and a small amount of an organic or mineral acid under a shear rate of more than 1000 kJ / s, and simultaneously or sequentially reacting the rare earth oxide with the organic phosphoric acid and the small amount of the organic or mineral acid. The expression "high shear dispersion" in Patent Document 4 refers to dispersion performed while stirring at a high blade tip peripheral speed of more than 4 m / s.

[0007] However, there remains a need for a method for preparing a neodymium alkyl phosphate solution in an organic solvent that exhibits low viscosity combined with a high neodymium content and does not contain residual rare earth precursors or any other impurities in amounts harmful to any subsequent use. Ideally, such a method would involve gentle mixing, requiring low energy input and not requiring investment in additional industrial-scale reactor equipment. In particular, there is a continuing need to provide a neodymium(III) alkyl phosphate solution that does not contain substances that adversely affect the environment and / or activity of the target catalyst system, such as tin(IV) tetrachloride, which is used as a viscosity reducer in U.S. Patent Nos. 5,627,999 and 5,792,499. Furthermore, there is a need to provide a method for preparing a neodymium alkyl phosphate solution in an organic solvent that is suitable for producing precursors to highly active catalyst systems for the cis-1,4 polymerization of conjugated dienes. Furthermore, there is a need to provide a method for preparing a neodymium alkyl phosphate solution in an organic solvent that effectively prevents or at least significantly limits gel formation. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] U.S. Patent No. 6,197,713 [Patent Document 2] U.S. Patent No. 8,404,821 [Patent Document 3] U.S. Patent No. 7,906,631 [Patent Document 4] U.S. Patent No. 9,090,637 Summary of the Invention

[0009] The object of the present invention was to solve one or more of the above-identified problems and / or to meet one or more of the above-identified needs. Surprisingly, it was found that by adding an antigelling agent to a gel solution obtained by reacting a neodymium(III) precursor, which may be selected from, for example, neodymium oxide, neodymium hydroxide and their hydrates, with an organophosphoric acid in a non-polar organic solvent in the presence of a promoter at reflux temperature, it is possible to obtain, without applying high shear rates, a clear, low-viscosity solution of a neodymium alkyl phosphate suitable for producing a precursor of a highly active catalyst system for the cis-1,4 polymerization of conjugated dienes.

[0010] In a first aspect, the present invention provides a method for producing a neodymium(III) alkyl phosphate solution, comprising the steps of: (a) reacting a neodymium(III) compound with an organic phosphoric acid in a solvent in the presence of a promoter, thereby obtaining a neodymium(III) alkyl phosphate solution; (b) adding an anti-gelling agent to the neodymium(III) alkyl phosphate solution obtained in step (a); (c) removing water formed and / or added during step (a) from the resulting neodymium(III) alkyl phosphate solution, thereby obtaining a solution comprising neodymium(III) alkyl phosphate.

[0011] In the context of the present invention, the term "promoter" refers to any compound capable of promoting or catalyzing the reaction between the neodymium(III) compound and the organophosphoric acid. In a preferred embodiment of the present invention, the promoter is water. In a preferred embodiment of the present invention, the promoter is preferably added during step (a). Preferably, the promoter, preferably water, is added at the start of the reaction in step (a). The promoter may be added during step (a) to compensate for the evaporation of at least a portion of the water present in the reaction mixture and / or to control the content of the promoter, particularly water, in the reaction mixture. In a preferred embodiment of the present invention, the promoter, preferably water, is at least partially removed after step (a) and / or after step (b). The promoter, particularly water, may be removed by distillation, preferably azeotropic distillation.

[0012] In the context of the present invention, the term "antigelling agent" is considered synonymous with the terms "gel breaker," "gel breaking agent," or "antigel agent" and refers to any compound capable of reducing the viscosity of a gel matrix formed by a neodymium(III) alkyl phosphate in solution and / or essentially preventing the formation of a gel matrix containing a neodymium(III) alkyl phosphate. Preferably, such an antigelling agent reduces the viscosity of the resulting solution to less than 150 dPa·s. The antigelling agent is added after the reaction of the neodymium(III) compound with the organophosphoric acid, i.e., after the formation of the neodymium(III) alkyl phosphate in solution. When the antigelling agent is a gaseous compound such as hydrochloric acid, it is preferably added at a low temperature after the completion of the reaction of the neodymium(III) compound with the organophosphoric acid, for example, by cooling the reaction mixture to a temperature below 60°C, preferably below 50°C, and more preferably below 40°C. Cooling to a temperature below room temperature, ie, about 20°C to 25°C, is not advantageous.

[0013] The method of the present invention allows for the preparation of neodymium-based organophosphate compounds in solution via a novel, alternative, gentle mixing process that is easily carried out in a one-pot procedure at low shear rates. The compounds in solution are also easily purified, eliminating, for example, additional washing steps as reported for certain prior art procedures. Advantageously, the method of the present invention ensures that the compounds in the resulting solution do not form gels. Gel formation typically occurs in neodymium(III) alkylphosphate solutions, which is believed to be due to the formation of oligomeric and / or polymeric neodymium(III) complexes. Such gelation makes the resulting solution difficult to handle and difficult to dispense when used as a catalyst precursor system for diene polymerization reactions. This, in turn, affects the quality of the resulting diene polymer.

[0014] In a preferred embodiment, the present invention provides a method according to the first aspect of the present invention, wherein steps (a), (b), and (c) are carried out sequentially. In another preferred embodiment, the present invention provides a method according to the first aspect of the present invention, wherein water is removed in step (c) until a neodymium concentration of at least 3 wt. % based on the total weight of the neodymium(III) alkyl phosphate solution is reached. Preferably, water is removed in step (c) until a neodymium concentration of at least 4 wt. % is reached. Most preferably, water is removed in step (c) until a neodymium concentration of at least 5 wt. %, or even at least 6 wt. % is reached.

[0015] In a preferred embodiment, the present invention provides a method according to the first aspect of the present invention, wherein the neodymium(III) compound is reacted with the organophosphoric acid in step (a), whereby the organophosphoric acid is obtained in a stoichiometric excess amount relative to the amount of the neodymium(III) compound. Preferably, the organophosphoric acid is obtained in an amount of 3.0 to 3.40 equivalents of organophosphoric acid per equivalent of neodymium(III) compound, preferably 3.00 to 3.34, 3.10 to 3.30, or even 3.15 to 3.25 equivalents of organophosphoric acid per equivalent of neodymium(III) compound.

[0016] In a preferred embodiment, the present invention provides a method according to the first aspect of the present invention, wherein the neodymium(III) compound is selected from the group consisting of neodymium(III) oxide, neodymium(III) hydroxide, neodymium(III) carbonate, and hydrates thereof. Preferably, the Neostream(III) compound is selected from the group consisting of neodymium oxide, neodymium hydroxide, and hydrates thereof, and most preferably, the Neostream(III) compound is neodymium oxide or a hydrate thereof. Preferred neodymium(III) compounds provide excellent conversion in reaction with the organophosphate.

[0017] In a preferred embodiment, the invention provides a process according to the first aspect of the invention, wherein the organophosphate is selected from the group consisting of a phosphoric acid diester of formula (RO)(R'O)PO(OH), a phosphoric acid monoester of formula (RO)P(O)(OH), a phosphonate of formula (RO)R'P(O)(OH) or R(O)(OH), a phosphinate R(R')P(O)OH or R(H)P(O)OH, and mixtures of two or more of the foregoing, wherein each of R and R', if present, independently represents an n-butyl, isobutyl, pentyl, amyl, isopentyl, 2,2-dimethylhexyl, 2-ethylhexyl, 1-ethylhexyl, tolyl, nonylphenoxy radical.

[0018] In a preferred embodiment, the present invention provides a method according to the first aspect of the invention, wherein the organophosphate is bis(2-ethylhexyl) hydrogen phosphate, which in the context of the present invention is abbreviated as DEHPA.

[0019] In a preferred embodiment, the present invention provides a process according to the first aspect of the present invention, wherein the molar ratio of bis(2-ethylhexyl) hydrogen phosphate to neodymium is in the range of 3.00 to 3.40.

[0020] In a preferred embodiment, the molar ratio of bis(2-ethylhexyl) hydrogen phosphate to neodymium is in the range of 3.00 to 3.34, preferably 3.10 to 3.30, and more preferably 3.15 to 3.25. It has been found that low molar ratios of DEPHA to neodymium do not allow complete conversion of the starting material, while high molar ratios of DEPHA to neodymium tend to be unstable, as observed by spontaneous phase separation. Most preferably, the molar ratio of DEPHA to neodymium is about 3.16, 3.18, 3.20, or 3.22, or any value therebetween.

[0021] In a preferred embodiment, the present invention provides a process according to the first aspect of the invention, wherein the solvent is a hydrocarbon solvent. Preferably, the hydrocarbon solvent comprises an aliphatic or alicyclic alkane.

[0022] In a preferred embodiment, the aliphatic or alicyclic alkane has 6 to 9 carbon atoms, preferably 6 to 8 carbon atoms, and most preferably 7 carbon atoms. In a preferred embodiment, the solvent is selected from the group consisting of n-hexane, n-heptane, cyclopentane, cyclohexane, methylcyclohexane, and mixtures thereof. Most preferably, the solvent is methylcyclohexane.

[0023] In a preferred embodiment, the present invention provides a method according to the first aspect of the invention, wherein the antigelling agent is a non-tin based antigelling agent. In another preferred embodiment, the present invention provides a method according to the first aspect of the invention, wherein the antigelling agent comprises one or more compounds selected from the group consisting of: mineral acids selected from the group consisting of perchloric acid HClO4, chloric acid HClO3, chlorous acid HClO2, hydrochloric acid HCl, bromic acid HBrO3, hydrobromic acid HBr, iodic acid HIO3, periodic acid HIO4, orthoperiodic acid H5IO6, hydroiodic acid HI, nitric acid HNO3, peroxonic acid HNO4 and silicic acid H4SiO4, organic acids selected from the group consisting of trichloroacetic acid CCl3-COOH, dichloroacetic acid CCl2H-COOH and trifluoroacetic acid CF3COOH, Lanthanide halides, lanthanide nitrates, and their hydrates; Silicon(IV) halides, such as silicon(IV) tetrahalides, Alkyl halides, and ·Silicon(IV) esters.

[0024] In a more preferred embodiment, the present invention provides a method according to the first aspect of the present invention, wherein the antigelling agent is a non-tin-based antigelling agent comprising one or more compounds selected from the group listed above. All of the preferred antigelling agents listed above have proven to be non-toxic to neodymium(III) alkylphosphate-based catalyst systems. They are very effective in small amounts, yet do not interfere with the catalyst system.

[0025] In a preferred embodiment, the anti-gelling agent comprises hydrochloric acid. In another preferred embodiment, the anti-gelling agent comprises a lanthanide halide, preferably neodymium(III) chloride or a hydrate thereof. In another preferred embodiment, the anti-gelling agent has the general formula R m H n Six p wherein X is a halide selected from Cl, Br, and I, and X is preferably Cl; p is an integer from 1 to 4; m and n are, independently, integers from 0 to 3, such that m+n+p=4. Preferred silicon(IV) halides are dichlorodimethylsilane, chlorodimethylsilane, and silicon tetrachloride. In an alternative or complementary embodiment, the antigelling agent comprises an alkyl chloride, preferably chloroform. In yet another preferred embodiment, the antigelling agent comprises a silicon(IV) carboxylate, preferably silicon(IV) 2-ethylhexanoate.

[0026] In a preferred embodiment, the present invention provides a method according to the first aspect of the invention, wherein the antigelling agent is selected from the group consisting of hydrochloric acid HCl, hydrobromic acid HBr, hydroiodic acid HI, neodymium(III) chloride NdCl3, silicon tetrachloride SiCl4 and / or Si(IV) 2-ethylhexanoate.

[0027] Preferably, the anti-gelling agent is hydrochloric acid HCl, neodymium (III) chloride NdCl3, or silicon tetrachloride SiCl4, or a combination of two or more of the foregoing. In a preferred embodiment, the present invention provides a method according to the first aspect of the invention, wherein step (a) is carried out in the absence of an anti-gelling agent. In an alternative preferred embodiment, the present invention provides a method according to the first aspect of the invention, wherein an anti-gelling agent is added to the neodymium(III) compound in step (a), the anti-gelling agent being selected from the group consisting of silicic acid (H4SiO4) and silicon(IV) esters.

[0028] In a preferred embodiment, the anti-gelling agent is a silicon(IV) carboxylate, preferably silicon(IV) 2-ethylhexanoate. In a preferred embodiment, the present invention provides a method according to the first aspect of the present invention, wherein the molar ratio of the antigelling agent to neodymium is in the range of 0.05 to 0.45, preferably 0.05 to 0.35, more preferably 0.05 to 0.30.

[0029] In preferred embodiments, the molar ratio of antigelling agent to neodymium is in the range of 0.05 to 0.25, more preferably in the range of 0.08 to 0.15, and most preferably about 0.08, 0.10, 0.12, or 0.14, or any value therebetween.

[0030] In a preferred embodiment, the present invention provides a method according to the first aspect of the invention, wherein the promoter present in step (a) is selected from: Water in a molar ratio to neodymium ranging from 0.1 to 25; Chloroform used in a molar ratio to neodymium ranging from 0.1 to 25; A mixture of water and chloroform, wherein the molar ratio of the mixture to neodymium is in the range of 0.1 to 25.

[0031] In a preferred embodiment, the promoter is water, and the molar ratio of water to neodymium is 0.1-10, preferably 0.1-5. In a preferred embodiment, the present invention provides a process according to the first aspect of the invention, wherein the molar ratio of the promoter present in step (a) to neodymium is in the range of 0.1 to 5.

[0032] In a preferred embodiment, the promoter is water and the molar ratio of water to neodymium is from 0.1 to 2, more preferably the molar ratio is about 0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, 1.6, 1.8 or 2.0, or any value therebetween.

[0033] In a preferred embodiment, the present invention provides a process according to the first aspect of the invention, wherein after step (b), more preferably after step (c), at least a portion of the solvent is removed by distillation. Preferably, the amount of solvent removed from the neodymium(III) alkyl phosphate solution is predetermined to reach the desired neodymium concentration in the solution, and the solution comprises a remaining amount of solvent.

[0034] In a preferred embodiment, the present invention provides a process according to the first aspect of the invention, wherein the neodymium(III) compound is reacted with the organophosphoric acid at a temperature of at least 50° C., preferably at least 60° C., more preferably at least 65° C. Most preferably, the reaction is carried out at reflux under atmospheric pressure.

[0035] Furthermore, the method of the present invention allows for the production of neodymium(III) alkylphosphate solutions without the application of high shear rates. In a preferred embodiment, the present invention involves reacting the neodymium(III) compound with the organophosphoric acid in the presence of a promoter, thereby allowing the reaction to proceed for 200 seconds. -1 The present invention provides a method according to the first aspect of the present invention, which provides a neodymium(III) alkyl phosphate solution at a shear rate of 1000 rpm. It is very important to avoid high shear rates, especially on an industrial scale. Not only are high shear rates associated with a large amount of energy input, but the reactor usually needs to be modified with additional equipment. In a further preferred embodiment, a nitrogen stream can be introduced into the reactor from below to ensure sufficient mixing.

[0036] In a further aspect, the present invention provides a neodymium(III) alkyl phosphate solution characterized by a neodymium content in the range of 6% to 10% (w / w), preferably 6% to 8% (w / w) or even 6.5% to 7.5% (w / w), more preferably 6.9% to 7.3% (w / w), a chloride content in the range of 500 to 5000 ppm, preferably 1000 to 3000 ppm, more preferably 1400 to 2300 ppm, a water content not exceeding 500 ppm, more preferably not exceeding 220 ppm, and a free alkyl phosphate content of 0 to 10% (w / w), preferably 2 to 7% (w / w), more preferably 4.0 to 6.6% (w / w).

[0037] In a still further aspect, the present invention provides the use of a neodymium(III) alkyl phosphate solution obtainable by the process according to the first aspect of the present invention as a catalyst precursor for diene polymerization reactions. In a preferred embodiment, the neodymium(III) alkyl phosphate is neodymium(III) bis(2-ethylhexyl) phosphate and the free alkyl phosphate is bis(2-ethylhexyl) hydrogen phosphate. DETAILED DESCRIPTION OF THE INVENTION

[0038] Detailed Description of the Invention Example Neodymium(III) alkylphosphate solutions were synthesized as detailed below and their parameters were characterized by the following techniques.

[0039] Characterization Techniques The weight contents of Nd and neodymium bis(2-ethylhexyl)phosphate (NdP) based on the total neodymium(III) alkyl phosphate solution were determined by complexometric titration using EDTA as the titrant. The weight content of free DEHPA based on the total neodymium(III) alkyl phosphate solution was determined by potentiometric titration. The amount of chlorine was determined by precipitation titration using silver nitrate as the titrant. The amount of water was determined by the Karl Fischer method. The viscosity of the neodymium(III) alkyl phosphate solution was measured using an Anton Paar Physica MCR51 rheometer. Unless otherwise stated, the solution concentration was adjusted to 45% (w / w). The measurement temperature was 25°C, and the viscosity values ​​were expressed as 10 s -1 was determined for a shear rate of .

[0040] The inventors were able to scale up all of the syntheses described below from laboratory scale to industrial scale. For this purpose, a reactor designed for viscous products was used. The reactor's internal diameter was 1775 mm, thus giving a nominal volume of approximately 5 MT (approximately 6250 L). The reactor contained two counter-rotating agitators. The outer agitator had an anchor and two blades with a diameter of 1630 mm, which was driven by a 15 kW motor to achieve a rotation speed of 21 rpm and a peripheral blade tip speed of 1.43 m / s. The inner agitator had three blades with a diameter of 1300 mm and a rotation speed of 20 rpm and a peripheral blade tip speed of 1.36 m / s, which was driven by an 11 kW motor.

[0041] Counterexample 1 [CE1]: Synthesis of neodymium bis(2-ethylhexyl) phosphate solution according to US 6,197,713 Neodymium oxide (20 g, 0.06 mol) was added to a four-neck, 1-liter round-bottom flask equipped with a Dean-Stark trap, a condenser, and a mechanical stirrer. The experimental kit was flushed with nitrogen for 10 minutes. Then, bis(2-ethylhexyl) hydrogen phosphate (97.5% purity) (122.65 g, 0.371 mol) was poured into the flask, rinsed with methylcyclohexane (560 ml), and 20 ml of water was added to obtain a slurry. The solution was heated to 80 °C and refluxed until a milky, pale purple solution was formed (approximately 7 hours). The viscosity of the reaction mixture increased during the process, requiring the stirrer speed to be increased from 350 rpm to 500 rpm. Water was then removed by azeotropic distillation. During the azeotropic distillation, the internal temperature rose to 100 °C. As a result of the azeotropic distillation, a clear gel solution was obtained with the following parameters:

[0042] [Table 1]

[0043] To the cooled gel solution, 1.2 ml of anhydrous tin tetrachloride was added. Excess solvent was then evaporated to give a final solution with the following parameters:

[0044] [Table 2]

[0045] Counterexample 2 [CE2]: Synthesis of neodymium bis(2-ethylhexyl) phosphate solution according to US 8,404,821 Neodymium oxide (20 g, 0.06 mol) was added to a four-necked, 1-liter round-bottom flask equipped with a Dean-Stark trap, a condenser, and a mechanical stirrer (500 rpm). The experimental kit was flushed with nitrogen for 10 minutes. Then, bis(2-ethylhexyl) hydrogen phosphate (97.5% purity) (135 g, 0.400 mol) was poured into the flask and rinsed with methylcyclohexane (780 ml). A slurry was obtained, to which 6.8 ml of 1 M hydrochloric acid was added. Under constant stirring, the mixture was heated to 80 °C, maintained at this temperature for 3 hours, and then cooled. Furthermore, as taught in US 8,404,821, the resulting mixture was washed three times with water (20 g per wash step) to remove residual hydrochloric acid. For each wash step, the mixture was stirred for 30 minutes, followed by 30 minutes of settling. Only in the final wash step was settling continued for 12 hours. After the final washing step, the upper layer showed high viscosity. Water was then removed by azeotropic distillation. During the azeotropic distillation, the internal temperature rose to 100°C. As a result of the azeotropic distillation, a clear gel solution was obtained with the following parameters:

[0046] [Table 3]

[0047] Counterexample 3 [CE3]: Synthesis of neodymium bis(2-ethylhexyl) phosphate solution according to US 7,906,631 Neodymium oxide (20 g, 0.06 mol) was added to a four-neck, 1-liter round-bottom flask equipped with a Dean-Stark trap, a condenser, and a mechanical stirrer (500 rpm). The flask was flushed with nitrogen for 10 minutes. Next, bis(2-ethylhexyl) hydrogen phosphate (97.5% purity) (119.05 g, 0.36 mol) was poured into the flask and rinsed with methylcyclohexane (780 ml) to obtain a slurry. To this, 1.65 g of 35% (w / w) hydrochloric acid was added. The slurry was stirred to obtain a solution. The temperature of the reaction solution was raised to 45 °C. While the reaction continued at this temperature, the reaction solution became translucent. The temperature of the reaction solution was then gradually increased to 65 °C by heating. The reaction was continued at this temperature until the solution became transparent, indicating completion of the reaction. Further water was removed by azeotropic distillation to obtain a final solution with a concentration of about 20% (w / w) (the concentration was lower than in US 7,906,631 due to the lower amount of solvent evaporated during azeotropic distillation). As a result of the azeotropic distillation, a clear gel solution was obtained with the following parameters:

[0048] [Table 4]

[0049] Due to the extremely high viscosity of the product, it was not possible to obtain a solution with a concentration of at least 45% (w / w). Example 1 [E1]: Synthesis of neodymium bis(2-ethylhexyl) phosphate solution Neodymium oxide (20 g, 0.06 mol) was added to a four-neck, 1-liter round-bottom flask equipped with a Dean-Stark trap, a condenser, and a mechanical stirrer. The experimental kit was flushed with nitrogen for 10 minutes. Then, bis(2-ethylhexyl) hydrogen phosphate (97.5% purity) (122.65 g, 0.371 mol) was poured into the flask, rinsed with methylcyclohexane (560 ml), and 20 ml of water was added to obtain a slurry. The solution was heated to 80 °C and refluxed until a milky, pale purple solution was formed (approximately 7 hours). The viscosity of the reaction mixture increased during the process, requiring the stirrer speed to be increased from 350 rpm to 500 rpm. Water was then removed by azeotropic distillation. During the azeotropic distillation, the internal temperature rose to 100 °C. As a result of the azeotropic distillation, a clear gel solution was obtained with the following parameters:

[0050] [Table 5]

[0051] To the cooled gel solution was added 1.2 ml of anhydrous silicon tetrachloride, followed by removal of excess solvent to give a concentrated, stable, clear purple solution with the following parameters:

[0052] [Table 6]

[0053] Example 2 [E2]: Synthesis of neodymium bis(2-ethylhexyl) phosphate solution Neodymium oxide (20 g, 0.06 mol) was added to a four-neck, 1-liter round-bottom flask equipped with a Dean-Stark trap, a condenser, and a mechanical stirrer. The experimental kit was flushed with nitrogen for 10 minutes. Then, bis(2-ethylhexyl) hydrogen phosphate (97.5% purity) (122.65 g, 0.371 mol) was poured into the flask and rinsed with methylcyclohexane (560 ml). Water (20 ml) and tin(II) ethylhexanoate (3.3 ml, 0.01 mol) were added to the resulting slurry. The solution was heated to 80 °C and refluxed until a milky, pale purple solution was formed (approximately 7 h). The viscosity of the reaction mixture increased during this process, requiring the stirrer speed to be increased from 350 rpm to 500 rpm. Upon completion of the reaction, water was removed by azeotropic distillation. During the azeotropic distillation, the internal temperature rose to 100 °C. After distillation, the water content was 170 ppm. As a result of azeotropic distillation, excess solvent was removed to give a stable purple, slightly cloudy solution with the following parameters:

[0054] [Table 7]

[0055] Example 3 [E3]: Synthesis of neodymium bis(2-ethylhexyl) phosphate solution Neodymium oxide (20 g, 0.06 mol) was added to a four-neck, 1-liter round-bottom flask equipped with a Dean-Stark trap, a condenser, and a mechanical stirrer. The experimental kit was flushed with nitrogen for 10 minutes. Next, bis(2-ethylhexyl) hydrogen phosphate (97.5% purity) (122.65 g, 0.371 mol) was poured into the flask and rinsed with methylcyclohexane (560 ml). Water (20 ml) and silicon(IV) 2-ethylhexanoate (6.0 g, 0.01 mol) were added to the resulting slurry. The solution was heated to 80 °C and refluxed until a milky, pale purple solution was formed (approximately 7 hours). Although no increase in viscosity of the reaction mixture was observed during this process, the stirrer speed was increased from 350 rpm to 500 rpm. Upon completion of the reaction, water was removed by azeotropic distillation. At this stage, gel formation was observed. 1.25 ml of 37% (w / w) hydrochloric acid was added to the mixture after the reaction to reduce the viscosity. During the azeotropic distillation, the internal temperature rose to 100°C. After distillation, the water content was 210 ppm. As a result of the azeotropic distillation, excess solvent was removed to obtain a stable, purple, clear solution with the following parameters:

[0056] [Table 8]

[0057] Example 4 [E4]: Synthesis of neodymium bis(2-ethylhexyl) phosphate solution Neodymium oxide (20 g, 0.06 mol) was added to a four-neck, 1-liter round-bottom flask equipped with a Dean-Stark trap, a condenser, and a mechanical stirrer. The experimental kit was flushed with nitrogen for 10 minutes. Then, bis(2-ethylhexyl) hydrogen phosphate (97.5% purity) (122.65 g, 0.371 mol) was poured into the flask, rinsed with methylcyclohexane (560 ml), and a slurry was obtained, to which 20 ml of water was added. The solution was heated to 80 °C and refluxed until a milky, pale purple solution was formed (approximately 7 hours). The viscosity of the reaction mixture increased during the process, requiring the stirrer speed to be increased from 350 rpm to 500 rpm. Upon completion of the reaction, the reaction mixture was cooled. 1.25 ml of 37% (w / w) hydrochloric acid was added to the mixture to reduce the viscosity. The solution was stirred at a temperature below 50 °C for 30 minutes, followed by azeotropic distillation to remove the water. During the azeotropic distillation, the internal temperature rose to 100°C. After distillation, the water content was 300 ppm. As a result of the azeotropic distillation, excess solvent was removed, resulting in a concentrated, stable, purple, clear solution with the following parameters:

[0058] [Table 9]

[0059] Example 5 [E5]: Synthesis of neodymium bis(2-ethylhexyl) phosphate solution Neodymium oxide (20 g, 0.06 mol) was added to a four-neck, 1-liter round-bottom flask equipped with a Dean-Stark trap, a condenser, and a mechanical stirrer. The experimental kit was flushed with nitrogen for 10 minutes. Then, bis(2-ethylhexyl) hydrogen phosphate (97.5% purity) (122.65 g, 0.371 mol) was poured into the flask, rinsed with methylcyclohexane (560 ml), and a slurry was obtained, to which 20 ml of water was added. The solution was heated to 80 °C and refluxed until a milky, pale purple solution was formed (approximately 7 hours). Because the viscosity of the reaction mixture increased during this process, the stirrer speed was increased from 350 rpm to 500 rpm. Once the reaction was complete, the reaction mixture was cooled. Then, 1.2 g of NdCl3 was added to the mixture to reduce the viscosity. The solution was stirred at a temperature below 50 °C for 30 minutes, followed by azeotropic distillation to remove the water. During the azeotropic distillation, the internal temperature rose to 100°C. After distillation, the water content was 300 ppm. As a result of the azeotropic distillation, excess solvent was removed, resulting in a concentrated, stable, purple, clear solution with the following parameters:

[0060] [Table 10]

[0061] Example 6 [E6]: Synthesis of neodymium bis(2-ethylhexyl) phosphate solution Neodymium oxide (20 g, 0.06 mol) was added to a four-neck, 1-liter round-bottom flask equipped with a Dean-Stark trap, a condenser, and a mechanical stirrer. The experimental kit was flushed with nitrogen for 10 minutes. Then, bis(2-ethylhexyl) hydrogen phosphate (97.5% purity) (122.65 g, 0.371 mol) was poured into the flask, rinsed with methylcyclohexane (560 ml), and a slurry was obtained, to which 90 ml of chloroform was added. The solution was heated to 80 °C and refluxed until a milky, pale purple solution was formed (approximately 2 hours). The viscosity of the reaction mixture increased during this process, so the stirrer speed was increased from 350 rpm to 500 rpm. Water and chloroform were then removed by azeotropic distillation. During the azeotropic distillation, the internal temperature rose to 100 °C. After the azeotropic distillation, the reaction mixture was cooled. 1.25 ml of 37% (w / w) hydrochloric acid was added to the mixture to reduce the viscosity. The solution was stirred at a temperature below 50°C for 30 minutes, followed by removal of water by azeotropic distillation. During the azeotropic distillation, the internal temperature rose to 100°C. After distillation, the water content was 160 ppm. As a result of the azeotropic distillation, excess solvent was removed, resulting in a concentrated, stable, purple, clear solution with the following parameters:

[0062] [Table 11]

[0063] Example 7: Preparation of catalytic system and activity evaluation Catalyst systems were prepared using the neodymium bis(2-ethylhexyl) phosphate solutions of Comparative Examples 1-3 and Examples 1-6 according to the procedures and under the conditions detailed in U.S. Pat. No. 9,090,637, which is incorporated herein by reference in its entirety.

[0064] The catalytic activity of all nine resulting catalyst systems was measured by conversion rate in a polymerization reaction also carried out according to the conditions disclosed in detail in US 9090637. The activity test results are provided in Table 1 below.

[0065] [Table 12]

[0066] Catalysts 1 and 5 showed poor conversion, likely due primarily to the adverse effect of residual tin. Catalyst 2 was in the form of a highly viscous solution, which adversely affected its activity. Only catalysts that passed the activity test (reaching 100% conversion in 30 minutes), namely catalysts 4, 6, 7, 8, and 9, were further tested in NdBR polymerization.

[0067] Examples 1B-6B: Batch Coordination Polymerization of 1,3-Butadiene Using Nd-Containing Catalysts Catalysts 4 to 9 obtained in Example 7 above were used for the polymerization of 1,3-butadiene. The general principles and procedures for 1,3-butadiene homopolymerization using Nd-based catalyst systems have been described by Friebe L., Nuyken O., and Obrecht W. in “A Comparison of Neodymium Versatate, Neodymium Neopentanolate, and Neodymium Bis(2-ethylhexyl)phosphate in Ternary Ziegler Type Catalyst Systems With Regard to Their Impact on the Polymerization of 1,3-Butadiene” in Journal of Macromolecular Science, Part A: Pure and Applied Chemistry, (2005), 42, 7, 839-851, and by Friebe L., Nuyken O., and Obrecht W. in “Polymerization of 1,3-butadiene initiated by neodymium versatate / diisobutylaluminum hydride / ethylaluminum sesquichloride: Kinetics and conclusions about the polymerization of 1,3-butadiene” in Macromol. Chem. Phys., (2002), 203, 8, 1055-1064. The present invention is described by Friebe, L., Nuyken, O., Windisch, H., and Obrecht, W. in "A Novel Reaction Mechanism of the Fluorescent Ion Beams."

[0068] polymerization Batch polymerization of 1,3-butadiene was achieved according to the following procedure. A 20-liter reactor was charged with dry 1,3-butadiene and dry solvent (cyclohexane) and heated to 80°C. Diisobutylaluminum hydride (DIBAH) (0.1 M / L solution in cyclohexane) was then added. Polymerization was initiated by adding the catalyst solution. The reaction mixture was heated and continuously stirred throughout the entire process. The temperature of the reaction mixture was maintained between 60 and 90°C. The polymerization was terminated using nitrogen-purged isopropyl alcohol. The resulting polymer solution was rapidly stabilized by adding 2-methyl-4,6-bis(octylsulfanylmethyl)phenol (1.0 phr of polymer).

[0069] The polymer solution was then transferred to a stripper. The reactor was flushed with a small amount of fresh cyclohexane, and its contents were also transferred to the stripper. Distilled water in an amount twice the total weight of the polymer solution, as well as a pH adjuster and soap, were added to the polymer solution, and the contents of the stripper were then treated with steam. Steam stripping was continued until all of the cyclohexane was removed and rubber crumb was obtained. The rubber crumb was then removed from the stripper, cooled to room temperature, crushed, and dried in a hot air stream.

[0070] Molecular weight determination Gel permeation chromatography was performed using a PSS Polymer Standards Service multicolumn (with a guard column) using THF as the eluent and for sample preparation. Multi-angle laser light scattering measurements were performed using a Wyatt Technologies Down Heleos II light scattering detector, a DAD (PDA) Agilent 1260 Infinity UV-VIS detector, and an Agilent 1260 Infinity refractive index detector.

[0071] Determination of vinyl content, cis-1,4 content, and trans-1,4 content (%) The microstructure of the butadiene rubber was determined by IR spectroscopy (Thermo Scientific Nicolet Is10). The following peak was used to quantitatively determine the microstructure of poly(butadiene): 735 cm -1 (δ(cis-R-CH=CR-H), →cis-1,4, ε=0.192), 91cm -1 (δ(R-CH=CH-H), → vinyl (1,2), ε=1.0), 965 cm -1 (δ(trans-R-CH=CR-H), → trans-1,4, ε=0.769). The methodology of this procedure is as described by M. Kraft, Struktur und Absorptionsspektroskopie der Kunststoffe, VCH, Weinheim 1973, p. 93, and by E. O. Schmalz, W. Kimmer in Z. Anal. Chem. 1961, 181, 229.

[0072] Glass transition temperature (℃) The glass transition temperature Tg was determined according to PN-EN ISO 11357-1:2009.

[0073] Mooney viscosity (ML(1+4) / 100℃) Mooney viscosity (MV) was determined according to ASTM D 1646-07 using a large rotor under the following conditions: preheat = 1 minute, rotor run time = 4 minutes, and temperature = 100°C.

[0074] The reaction conditions and the properties of the resulting polymer are presented in Table 2 below.

[0075] [Table 13]

[0076] Examples 1C-3C: Continuous Coordination Polymerization of 1,3-Butadiene Using Nd-Containing Catalysts In the batch processes of Examples 1B to 6B, all polymer samples showed nearly the same properties and very similar results in application tests, so continuous polymerizations on a pilot scale were carried out using only Catalyst 7. Continuous polymerization of 1,3-butadiene was achieved according to the following procedure.

[0077] A butadiene homopolymer was prepared in a series of two reactors, each with a volume of 10 L (first reactor) and 20 L (second reactor). Each reactor was equipped with a paddle stirrer. The stirring speed was 150-200 rpm, and the charge ratio was maintained at a level of 50%-90%. Cyclohexane, 1,3-butadiene, DIBAH solution, and catalyst solution were charged into the first reactor. The temperature in each reactor was 80-100°C. At the outlet of the second reactor, isopropanol (1.5 phr) was added as a reaction quenching liquid, followed by 2-methyl-4,6-bis(octylsulfanylmethyl)phenol (in the form of a hexane solution) (0.6 phr) as an antioxidant. The polymer was recovered by conventional solvent vapor stripping recovery procedures and then dried in a vacuum dryer for 12 hours.

[0078] The resulting rubbers were characterized according to the procedures described above in Examples 1B-6B. The reaction conditions and the properties of the resulting polymers are presented in Table 3 below.

[0079] [Table 14]

[0080] Example 8: Vulcanization of butadiene rubber obtained by batch process The rubbers obtained in Examples 1B, 2B, 3B, 4B, 5B, and 6B were compounded according to the compounding recipes shown in Table 4 below. Compounding of the solution styrene butadiene rubber, fillers, and rubber additives was carried out in a Banbury-type internal mixer (350E Brabender GmbH & Co. KG) and a laboratory-sized two-roll mill. The rubber compounds were compounded in two separate stages, with the final pass completed on the two-roll mill.

[0081] [Table 15]

[0082] The first stage (Stage 1) involved compounding the rubber with oil, silica, silane coupling agent, 6PPD, and activator in several steps. The compounded mixture was then allowed to rest for 24 hours. The second stage (Stage 2) involved compounding aimed at further improving the distribution of the silica, along with the addition of carbon black. The rubber compound was then conditioned for four hours before a final pass was made on a two-roll mill. In the next step, the vulcanization package was added to the rubber compound. After the addition of the vulcanization package, but before the vulcanization process, rheological measurements of the compound were performed. The following parameters were measured for the green (unvulcanized) compound:

[0083] Vulcanization characteristics Cure properties were determined using an RPA 2000 Alpha Technologies rubber process analyzer according to ASTM D6204, with a working time of 30 minutes and a temperature of 170°C.

[0084] After adding the vulcanization package, each rubber compound was heated to 170°C and 95×1.5 The rubber compounds were vulcanized for 10 minutes (based on the RPA results) to obtain vulcanizates. The following parameters were measured for each vulcanized rubber compound: tire predictor (tan δ and G* at 60°C, tan δ at 0°C, tan δ at -10°C, G' and J" at 30°C, and G' at -20°C). The vulcanized rubber compound test specimens were measured using a dynamic mechanical analyzer (DMA GABO EPLEXOR) in single shear mode under the conditions of dynamic strain = 2%, frequency = 10 Hz, at temperatures ranging from -80 to 65 °C, and a heating rate of 2.5 K / min.

[0085] Rebound elasticity The rebound resilience of the test vulcanized rubber samples was determined according to ISO 4662. Silica Dispersion Silica dispersion was determined using a disperGRADER Alpha Technologies according to ISO 1134 C, D, E, ASTM D7723.

[0086] The dynamic and mechanical properties of the vulcanizates resulting from the batch polymerization process are shown in Table 5 below.

[0087] [Table 16]

[0088] Example 9: Vulcanization of butadiene rubber obtained in a continuous process The rubbers obtained in Examples 1C, 2C, and 3C were compounded according to the compounding recipes shown in Table 6 below. The compounding of the solution styrene butadiene rubber, fillers, and rubber additives was carried out in a Farrel-type internal mixer (Mixer Farrel BR +1600) and a laboratory-sized two-roll mill. The rubber compounds were compounded in three different stages, the first two in the internal mixer and the third (final pass) on the two-roll mill.

[0089] [Table 17]

[0090] The first stage (Stage 1) involved compounding the rubber with oil, silica, silane coupling agent, 6PPD, and activator in several steps. The compounded mixture was then allowed to rest for 24 hours. The second stage (Stage 2) involved compounding with carbon black to further improve the distribution of the silica. The rubber compound was then conditioned for 4 hours before a final pass was made on a two-roll mill. In the next step, the vulcanization package was added to the rubber compound. After adding the vulcanization package, but before the vulcanization process, rheological measurements of the compound were performed. These measurements were accompanied by the determination of the vulcanization characteristics and Payne effect, performed according to the procedures already set forth in Example 8 above.

[0091] After adding the vulcanization package, each rubber compound was heated to 170°C and 95×1.5 The rubber compounds were then vulcanized for 10 minutes (based on the RPA results) to obtain vulcanizates. For each vulcanized rubber compound, the same parameters as those shown in Example 8 above, namely, tire predictor, rebound resilience, reinforcement coefficient, and silica dispersion, were measured.

[0092] The only difference is that for the tire predictor measurements, a different type of dynamic mechanical analyzer was used, namely, a DMA 450+MetraviB. The dynamic and mechanical properties of the vulcanizates resulting from the continuous polymerization process are shown in Table 7 below.

[0093] [Table 18]

[0094] The rubbers obtained in Examples 1B-6B (batch polymerization) and 1C-3C (continuous polymerization) were subjected to vulcanization in Examples 8 and 9, respectively. The obtained vulcanizates were compared with each other and with a reference butadiene rubber REF (a commercial grade of SYNTECA™ 44 by Synthos Group). The results are presented in Tables 5 and 7, respectively.

[0095] In all cases, tire predictors obtained from DMA, such as rolling resistance, dry handling, and wet grip, are very similar to the commercial grade SYNTECA™ 44. Mechanical properties are also very similar. The slight differences in the obtained values ​​are due to differences in the Mooney viscosity of the rubbers and the nature of the polymerization methods applied (batch vs. continuous process, pilot scale vs. industrial scale).

[0096] While certain representative embodiments and details have been shown for the purpose of illustrating the subject invention, it will be apparent to those skilled in the art that various changes and modifications can be made thereto without departing from the scope of the subject invention, which is defined by the following claims.

Claims

1. 1. A method for producing a neodymium(III) alkyl phosphate solution, comprising the steps of: (a) reacting a neodymium(III) compound with an organic phosphoric acid in a solvent in the presence of a promoter to obtain a neodymium(III) alkyl phosphate solution; (b) adding an anti-gelling agent to the neodymium(III) alkyl phosphate solution obtained in step (a); (c) removing water formed and / or added during step (a) from the resulting neodymium(III) alkyl phosphate solution to obtain a solution comprising neodymium(III) alkyl phosphate.

2. 10. The method of claim 1, wherein steps (a), (b), and (c) are performed sequentially.

3. 3. The method of claim 1 or 2, wherein water is removed in step (c) until a neodymium concentration of at least 3 wt. % based on the total weight of the neodymium(III) alkyl phosphate solution is achieved.

4. 4. The method according to claim 1, wherein the neodymium (III) compound is selected from the group consisting of neodymium (III) oxide, neodymium (III) hydroxide, neodymium (III) carbonate, and hydrates thereof.

5. The organic phosphoric acid may be a phosphoric acid diester of the formula (RO)(R'O)PO(OH), a phosphoric acid diester of the formula (RO)P(O)(OH), ２ phosphoric acid monoesters of the formula (RO)R'P(O)(OH) or RP(O)(OH) ２ 5. The method of any one of claims 1 to 4, wherein the radical R is selected from the group consisting of phosphonates, phosphinates R(R')P(O)OH or R(H)P(O)OH of the formula, and mixtures of two or more of the foregoing, wherein each of R and R', if present, independently represents an n-butyl, isobutyl, pentyl, amyl, isopentyl, 2,2-dimethylhexyl, 2-ethylhexyl, 1-ethylhexyl, tolyl, nonylphenoxy radical.

6. 6. The method of claim 5, wherein the organophosphate is bis(2-ethylhexyl) hydrogen phosphate.

7. 7. The method of claim 6, wherein the molar ratio of bis(2-ethylhexyl) hydrogen phosphate to neodymium is in the range of 3.00 to 3.

34.

8. The method according to any one of claims 1 to 7, wherein the solvent is a hydrocarbon solvent.

9. 9. The method of claim 1, wherein the antigelling agent is a non-tin based antigelling agent.

10. The method of any one of claims 1 to 9, wherein the anti-gelling agent comprises one or more compounds selected from the group consisting of: ・Perchloric acid HClO ４ , chloric acid HClO ３ , chlorite HClO ２ , hydrochloric acid HCl, bromic acid HBrO ３ , hydrobromic acid HBr, iodic acid HIO ３ , periodic acid HIO ４ , orthoperiodic acid H ５ IO ６ , hydroiodic acid HI, nitric acid HNO ３ , peroxoacetic acid HNO ４ and silicate H ４ SiO ４ a mineral acid selected from the group consisting of Trichloroacetic acid CCl ３ -COOH, dichloroacetic acid CCl ２ H—COOH and trifluoroacetic acid CF ３ an organic acid selected from the group consisting of COOH; Lanthanide halides, lanthanide nitrates, and their hydrates; silicon(IV) halides, alkyl halides, and Silicon (IV) esters.

11. The anti-gelling agent is selected from the group consisting of hydrochloric acid HCl, hydrobromic acid HBr, hydroiodic acid HI, and neodymium (III) chloride NdCl. ３ , silicon tetrachloride SiCl ４ and / or silicon(IV) 2-ethylhexanoate.

12. 12. The method of claim 10 or 11, wherein step (a) is carried out in the absence of an anti-gelling agent.

13. The anti-gelling agent is added to the neodymium (III) compound in step (a), and the anti-gelling agent is silicic acid (H ４ SiO ４ 11. The method of claim 10, wherein the silicon(IV) ester is selected from the group consisting of silicon(IV) esters.

14. 14. The method of any one of claims 1 to 13, wherein the molar ratio of the antigelling agent to neodymium is in the range of 0.05 to 0.

45.

15. The method of any one of claims 1 to 14, wherein the promoter present in step (a) is selected from: Water used in a molar ratio to neodymium ranging from 0.1 to 25; Chloroform used in a molar ratio to neodymium ranging from 0.1 to 25; A mixture of water and chloroform, wherein the molar ratio of the mixture to neodymium is in the range of 0.1 to 25.

16. 16. The method of claim 15, wherein the molar ratio of the promoter present in step (a) to neodymium ranges from 0.1 to 5.

17. 17. The method of any one of claims 1 to 16, wherein the neodymium(III) compound is reacted with the organophosphoric acid at a temperature of at least 50°C.

18. A neodymium(III) alkylphosphate solution obtainable by the method according to any one of claims 1 to 17.

19. 19. Use of a neodymium(III) alkylphosphate solution obtainable by the process according to any one of claims 1 to 18 as a catalyst precursor for diene polymerization.

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