Composite catalyst for nylon synthesis as well as preparation method and application of composite catalyst

Abstract

The invention discloses a composite catalyst for nylon synthesis and a preparation method and application thereof, the composite catalyst comprises a metal salt and a chiral phosphine ligand, has a six-coordination structure with double active sites, and can block intramolecular cyclization of butanediamine so as to effectively inhibit generation of a byproduct tetrahydropyrrole. Meanwhile, the composite catalyst can promote nucleophilic attack of the binary acid monomer and reduce the reaction activation energy of butanediamine and the binary acid monomer, so that the dehydration reaction process is promoted, and the polymerization process of the nylon polymer is realized. The composite catalyst is applied to synthesis of a nylon polymer based on a butanediamine monomer, the high-molecular-weight nylon polymer is directly synthesized by a one-step method, the pre-polymerization and solid-phase tackifying processes in a traditional nylon polymerization process are avoided, meanwhile, the powder material processing and modifying processes are also avoided, and the technological process is greatly simplified.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of high polymer material synthesis, and particularly relates to a composite catalyst for nylon synthesis and a preparation method and application thereof. BACKGROUND

[0002] As a diamine monomer, butanediamine (1,4-butanediamine) is combined with a dibasic acid through a polycondensation reaction in nylon synthesis to form a polyamide (nylon) with specific properties. Butanediamine-based nylon occupies an irreplaceable position in high-end industrial fields due to its unique high-temperature performance and mechanical strength, and its application potential in environmentally friendly materials will be further released as biobased technology matures.

[0003] For example, nylon 46 is a high-temperature nylon material synthesized by polycondensation of butanediamine and adipic acid, with a melting point as high as 290℃ and a long-term use temperature of 160℃. It is a special nylon material with high strength and strong heat resistance, and has been widely used in the fields of electronics, automobiles, machinery, etc.

[0004] The traditional nylon 46 polymerization process often needs to go through salt formation, pre-polymerization and solid-phase post-polymerization to obtain a final high-viscosity polymer material. This process is complicated and difficult to control, and the pre-polymer is a powder material that can easily block the filter during solid-phase viscosity increase. In addition, powder materials are difficult to modify and are not suitable for large-scale industrial production. At the same time, the traditional polymerization process cannot avoid the side reaction of cyclization of raw material butanediamine to form tetrahydropyrrole, resulting in an imbalance in raw material ratio and cyclization of polymer end groups, which cannot obtain high-viscosity polymer.

[0005] In previous studies on the preparation of high molecular weight nylon 46, salt formation, pre-polymerization and solid-phase polymerization were generally used, such as patents US4408036 and US4460762. Patent US4460762 adds 0.5-15 mol% excess 1,4-butanediamine to compensate for the loss of raw materials during polymerization. This method cannot inhibit the cyclization side reaction of butanediamine, and the excess proportion of butanediamine and the accuracy of the operating process temperature and pressure greatly limit the industrial production of nylon 46. In addition, Chinese patent CN 119613711A still uses salt formation, initial polymerization, pre-polymerization and solid-phase viscosity increase to synthesize nylon 46 polymer, and the reaction process is complicated. Patent CN 117887065 A uses 1,6-hexamethylene chloride and butanediamine to form salt in a low-boiling-point solvent, then stirs at high temperature, and extrudes the material at high temperature to obtain nylon 46 product. The process uses acyl chloride and solvent, which is not suitable for industrial production. Chinese patent CN102167815B uses supercritical carbon dioxide to prepare high molecular weight nylon 46, but the application of supercritical carbon dioxide in industry is much more complex than efficient polymerization catalyst systems, and does not have the conditions for large-scale production.

[0006] From the above studies, it is not difficult to find that the application of high-performance polymerization catalyst system in nylon polymers based on butanediamine monomer is very limited. The catalytic system such as acid or metal salt in the traditional nylon polymerization process cannot effectively inhibit the intramolecular cyclization of butanediamine to produce tetrahydro-pyrrole, thereby increasing the operation difficulty of nylon polymerization and hindering its industrial production.

[0007] Therefore, it is urgent to develop an efficient catalytic system for inhibiting the cyclization of butanediamine to produce tetrahydro-pyrrole and reducing end group capping, thereby obtaining high molecular weight nylon polymers based on butanediamine monomer. SUMMARY

[0008] The purpose of the present application is to overcome at least one of the above technical problems, and on the one hand to provide a composite catalyst for nylon synthesis. The composite catalyst has a double active site six-coordination structure, which can block the intramolecular cyclization of butanediamine, thereby effectively inhibiting the production of by-product tetrahydro-pyrrole. At the same time, the composite catalyst can also promote the nucleophilic attack of dibasic acid monomer, reduce the reaction activation energy of butanediamine and dibasic acid monomer, thereby promoting the dehydration reaction process and realizing the polymerization process of nylon polymer.

[0009] Another aspect of the present application is to provide a preparation method of the composite catalyst for nylon synthesis.

[0010] Another aspect of the present application is to provide a synthesis method of nylon polymers based on butanediamine monomer. The method applies the above composite catalyst to directly synthesize nylon polymers in one step, avoids the pre-polymerization and solid-phase tackification process in the traditional nylon polymer production process, and also avoids the powder material processing and modification process, greatly simplifying the process flow.

[0011] Another aspect of the present application is to provide the nylon polymers prepared by the above synthesis method.

[0012] In some embodiments, a composite catalyst for nylon synthesis is provided, which comprises a metal salt and a chiral phosphine ligand; the chiral phosphine ligand is a chiral bidentate phosphine ligand with C2 symmetry; and the composite catalyst has a double active site six-coordination octahedral structure.

[0013] Further, the metal salt is one or more of copper acetate, zinc acetate, cobalt acetate and iron acetate; preferably copper acetate or zinc acetate.

[0014] Further, the chiral bidentate phosphine ligand is one or more of R-(+)-2,2'-bis(diphenylphosphino)-1,1'-binaphthyl, (R)-(+)-2,2'-bis[di(3,5-dimethylphenyl)phosphino]-1,1'-binaphthyl, (R)-(+)-2,2'-bis(diphenylphosphino)-6,6'-dimethoxy-1,1'-biphenyl, and (R)-(+)-5,5'-bis(diphenylphosphino)-4,4'-bi-1,3-benzodioxole.

[0015] In some embodiments, a method for preparing a composite catalyst for nylon synthesis is provided, which comprises the following steps: adding a metal salt and a chiral bidentate phosphine ligand with C2 symmetry into an organic solvent, mixing and reacting under inert gas protection, adding cyclohexane after the reaction is cooled to obtain a precipitate, and drying the precipitate to obtain a composite catalyst with a six-coordinated octahedral structure having two active sites.

[0016] The metal salt is one or more of copper acetate, zinc acetate, cobalt acetate, and iron acetate; preferably, the metal salt is copper acetate or zinc acetate.

[0017] The chiral bidentate phosphine ligand is one or more of R-(+)-2,2'-bis(diphenylphosphino)-1,1'-binaphthyl, (R)-(+)-2,2'-bis[di(3,5-dimethylphenyl)phosphino]-1,1'-binaphthyl, (R)-(+)-2,2'-bis(diphenylphosphino)-6,6'-dimethoxy-1,1'-biphenyl, and (R)-(+)-5,5'-bis(diphenylphosphino)-4,4'-bi-1,3-benzodioxole.

[0018] Further, the molar ratio of the metal salt to the chiral phosphine ligand is 1:2 to 1:2.5; preferably, the molar ratio is 1:2 to 1:2.2.

[0019] Further, the organic solvent is one or a mixture of any proportion of toluene, tetrahydrofuran, and dioxane; preferably, the organic solvent is toluene.

[0020] Further, the reaction temperature is 90-120°C, and the reaction time is 12-24h.

[0021] In some embodiments, a method for synthesizing a nylon polymer based on a butanediamine monomer is provided, which comprises the following steps:

[0022] Step 1: adding butanediamine into deionized water, then adding a dibasic acid monomer to perform a salt formation reaction to obtain a salt solution;

[0023] Step 2: adding the composite catalyst of any one of claims 1-3 or the composite catalyst prepared by the preparation method of claim 4 or 5 into the obtained salt solution;

[0024] Step 3: then a stage polymerization reaction is carried out in a reaction kettle to obtain the nylon polymer.

[0025] The diacid monomer is an aliphatic diacid compound with 4-12 main chain carbon atoms or an aromatic diacid compound containing a phenyl group, a naphthyl group or a biphenyl group. For example, the diacid monomer can be adipic acid, sebacic acid, (ortho-, meta-, para-)terephthalic acid, dodecanedioic acid, etc. which are often used in nylon polymers.

[0026] Further, in step 1, the molar ratio of the diacid monomer to butanediamine is 1:(1-1.1); preferably 1:(1-1.05);

[0027] And / or, the concentration of the salt solution is 40-70wt%.

[0028] Further, in step 2, the molar ratio of the amount of the composite catalyst to the molar amount of butanediamine is (0.5-2):1000.

[0029] Further, in step 3, the stage polymerization reaction includes a salt solution dehydration reaction, a prepolymerization reaction and a final polymerization reaction.

[0030] The salt solution dehydration reaction temperature is 140-180℃, the pressure is 0.5-1.0MPa, and the reaction time is 2-5h;

[0031] The prepolymerization reaction temperature is 200-250℃, the pressure is 1.0-2.0MPa, and the reaction time is 2-4h;

[0032] The final polymerization reaction temperature is 260-320℃, the vacuum is extracted to a pressure of 1.0-5.0kPaA, and the reaction time is 1-4h.

[0033] In other embodiments, the synthesized nylon polymer is nylon 46, nylon 4T, nylon 46 / 4T, nylon 410 or nylon 412.

[0034] Compared with the prior art, the present application has the following beneficial effects:

[0035] 1. The composite catalyst provided by the present application has a six-coordination structure with double active sites, which can block the intramolecular cyclization of butanediamine, ensure the molar ratio of butanediamine to diacid monomer, reduce the consumption of butanediamine, and effectively inhibit the generation of by-product tetrahydropyrrole.

[0036] 2. The composite catalyst provided by the present application can effectively avoid the end-capping of the polymer, thereby realizing the direct synthesis of high molecular weight nylon polymer by one-step method.

[0037] 3. The composite catalyst provided by the present application can promote the nucleophilic attack of the dibasic acid, reduce the reaction activation energy of the butanediamine and the dibasic acid monomer, thereby promoting the dehydration reaction process, shortening the polymerization reaction time, realizing the polymerization process of the nylon polymer, and improving the production efficiency.

[0038] 4. The synthesis method of the high-temperature nylon polymer provided by the present application can realize the one-step direct synthesis of the high-molecular-weight nylon polymer by only adding a proper catalyst system. The method avoids the pre-polymerization and solid-phase tackification process in the traditional nylon polymerization process, and also avoids the powder material processing and modification process, thereby greatly simplifying the process flow. Therefore, the present application is simple and easy to implement, can obtain the nylon polymer with a higher molecular weight and produce less by-product tetrahydropyrrole, has good economic benefits, is environment-friendly, and is suitable for industrialized production. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments of the present application are clearly and completely described below. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor, or other embodiments obtained by adjusting the related parameters according to the data range of the present application, all fall within the protection scope of the present application.

[0040] The dibasic acid monomer is an aliphatic dibasic acid compound with 4-12 main chain carbon atoms or an aromatic dibasic acid compound containing a phenyl group, a naphthyl group or a biphenyl group. For example, the dibasic acid monomer can be adipic acid, sebacic acid, (ortho-, meta-, para-)terephthalic acid, dodecanedioic acid, etc., which are often used in nylon polymers. Those skilled in the art can understand that the specific type of the dibasic acid monomer is not limited, and the present application aims to solve the problem that the nylon polymer has a low molecular weight due to the internal cyclization of the butanediamine in the nylon polymerization. The change of the type of the dibasic acid monomer does not deviate from the core principle of the present application, and still falls within the protection scope of the present application.

[0041] Embodiment 1

[0042] 0.1 mol of copper acetate and 0.22 mol of R-(+)-2,2'-bis(diphenylphosphino)-1,1'-binaphthyl chiral phosphine ligand were added to 500 mL of toluene, stirred under nitrogen protection at 100℃ for 24 h, and then 300 mL of cyclohexane was added to obtain a precipitate. The obtained precipitate was dried to obtain the composite catalyst.

[0043]

[0044] R-(+)-2,2'-bis(diphenylphosphino)-1,1'-binaphthyl

[0045] Piperazine 88.15 g (1.0 mol) was added into 235 g deionized water, then adipic acid 146.14 g (1.0 mol) was slowly added under mechanical stirring to carry out the salt reaction, to obtain a salt solution. The pH of the salt solution was 7.1, and the concentration was 50 wt%. Then 0.0005 mol of the above composite catalyst was added into the salt solution, and after mixing uniformly, it was added into the polymerization kettle. After nitrogen replacement, the pressure was increased to 0.5 MPa, and the temperature was increased to 160°C to carry out the salt solution dehydration reaction, and the reaction time was 2 h. Then the temperature was continuously increased to 210°C to carry out the prepolymerization reaction, the reaction pressure was 1.5 MPa, and the time was 2 h. Then the temperature was continuously increased to 280°C to carry out the final polymerization reaction, slowly released to normal pressure, and vacuumed to 5.0 kPaA absolute pressure, and the time was 2 h. After the polymerization was completed, the melt discharge was carried out, and the polymer was transferred into water for rapid cooling, pelletizing to obtain nylon 46 polymer.

[0046] Comparative Example 1

[0047] Piperazine 88.15 g (1.0 mol) was added into 235 g deionized water, then adipic acid 146.14 g (1.0 mol) was slowly added under mechanical stirring to carry out the salt reaction, to obtain a salt solution. The pH of the salt solution was 7.1, and the concentration was 50 wt%. Then 0.0005 mol of the above composite catalyst was added into the salt solution, and after mixing uniformly, it was added into the polymerization kettle. After nitrogen replacement, the pressure was increased to 0.5 MPa, and the temperature was increased to 160°C to carry out the salt solution dehydration reaction, and the reaction time was 2 h. Then the temperature was continuously increased to 210°C to carry out the prepolymerization reaction, the reaction pressure was 1.5 MPa, and the time was 2 h. Then the temperature was continuously increased to 280°C to carry out the final polymerization reaction, slowly released to normal pressure, and vacuumed to 5.0 kPaA absolute pressure, and the time was 2 h. After the polymerization was completed, the melt discharge was carried out, and the polymer was transferred into water for rapid cooling, pelletizing to obtain nylon 46 polymer.

[0048] Comparative Example 2

[0049] Put 88.15 g (1.0 mol) of butanediamine into 235 g of deionized water, then slowly add 146.14 g (1.0 mol) of adipic acid under mechanical stirring to carry out a salt reaction. The pH of the salt solution is 7.1, and the concentration is 50 wt%. Then add 0.0005 mol of R-(+)-2,2'-bis(diphenylphosphino)-1,1'-binaphthyl to the salt solution, mix well, and then add to the polymerization kettle. After nitrogen replacement, pressurize to 0.5 MPa, and heat to 160°C to carry out a salt solution dehydration reaction, with a reaction time of 2 h. Then continue to heat to 210°C to carry out a prepolymerization reaction, with a reaction pressure of 1.5 MPa and a time of 2 h. Then continue to heat to 280°C to carry out a final polymerization reaction, slowly depressurize to normal pressure, and vacuumize to an absolute pressure of 5.0 kPa A, with a time of 2 h. After the polymerization is completed, melt discharge is carried out, and the polymer is transferred to water for rapid cooling, pelletization, and obtaining of a nylon 46 polymer.

[0050] Comparative Example 3

[0051] Put 88.15 g (1.0 mol) of butanediamine into 235 g of deionized water, then slowly add 146.14 g (1.0 mol) of adipic acid under mechanical stirring to carry out a salt reaction. The pH of the salt solution is 7.1, and the concentration is 50 wt%. Without adding any catalyst, the salt solution is directly added to the polymerization kettle. After nitrogen replacement, pressurize to 0.5 MPa, and heat to 160°C to carry out a salt solution dehydration reaction, with a reaction time of 2 h. Then continue to heat to 210°C to carry out a prepolymerization reaction, with a reaction pressure of 1.5 MPa and a time of 2 h. Then continue to heat to 280°C to carry out a final polymerization reaction, slowly depressurize to normal pressure, and vacuumize to an absolute pressure of 5.0 kPa A, with a time of 2 h. After the polymerization is completed, melt discharge is carried out, and the polymer is transferred to water for rapid cooling, pelletization, and obtaining of a nylon 46 polymer.

[0052] Comparative Example 4

[0053] Put 0.1 mol of copper acetate and 0.22 mol of triphenylphosphine achiral ligand into 500 mL of toluene, and stir under nitrogen protection at 100°C for 24 h. After cooling, add 300 mL of cyclohexane to obtain a precipitate; the obtained precipitate is dried to obtain a composite catalyst.

[0054] Diaminobutane 88.15 g (1.0 mol) was added into 235 g deionized water, then hexanedioic acid 146.14 g (1.0 mol) was slowly added under mechanical stirring to form a salt solution. The pH of the salt solution was 7.1 and the concentration was 50 wt%. Then the catalyst formed by the above-mentioned achiral phosphine ligand was added into the salt solution, and after being uniformly mixed, it was added into a polymerization kettle. After nitrogen replacement, the pressure was increased to 0.5 MPa, and the temperature was increased to 160°C to perform a salt solution dehydration reaction, and the reaction time was 2 h. Then the temperature was continuously increased to 210°C to perform a prepolymerization reaction, the reaction pressure was 1.5 MPa, and the time was 2 h. Then the temperature was continuously increased to 280°C to perform a final polymerization reaction, the pressure was slowly released to normal pressure, and vacuum was extracted to an absolute pressure of 5.0 kPaA, and the time was 2 h. After the polymerization was completed, melt discharge was performed, and the polymer was transferred to water for rapid cooling, pelletizing, and obtaining a nylon 46 polymer.

[0055] Example 2

[0056] Zinc acetate 0.1 mol and (R)-(+)-2,2'-bis[bis(3,5-dimethylphenyl)phosphino]-1,1'- binaphthyl 0.23 mol were added into 500 mL of toluene, stirred at 100°C under nitrogen protection for 24 h, and after cooling, 300 mL of cyclohexane was added to obtain a precipitate. The precipitate was dried to obtain a composite catalyst.

[0057]

[0058] (R)-(+)-2,2'-bis[bis(3,5-dimethylphenyl)phosphino]-1,1'-binaphthyl

[0059] Diaminobutane 88.15 g (1.0 mol) was added into 235 g deionized water, then hexanedioic acid 146.14 g (1.0 mol) was slowly added under mechanical stirring to form a salt solution. The pH of the salt solution was 7.1 and the concentration was 50 wt%. Then the catalyst formed by the above-mentioned achiral phosphine ligand was added into the salt solution, and after being uniformly mixed, it was added into a polymerization kettle. After nitrogen replacement, the pressure was increased to 0.5 MPa, and the temperature was increased to 160°C to perform a salt solution dehydration reaction, and the reaction time was 2 h. Then the temperature was continuously increased to 210°C to perform a prepolymerization reaction, the reaction pressure was 1.5 MPa, and the time was 2 h. Then the temperature was continuously increased to 280°C to perform a final polymerization reaction, the pressure was slowly released to normal pressure, and vacuum was extracted to an absolute pressure of 5.0 kPaA, and the time was 2 h. After the polymerization was completed, melt discharge was performed, and the polymer was transferred to water for rapid cooling, pelletizing, and obtaining a nylon 46 polymer.

[0060] Example 3

[0061] The complex catalyst was obtained by adding 0.1 mol of cobalt acetate and 0.21 mol of (R)-(+)-2,2'-bis(diphenylphosphino)-6,6'-dimethoxy-1,1'-biphenyl into 500 mL of toluene, stirring under nitrogen protection at 100°C for 24 h, adding 300 mL of cyclohexane after cooling, and drying the precipitate.

[0062]

[0063] (R)-(+)-2,2'-bis(diphenylphosphino)-6,6'-dimethoxy-1,1'-biphenyl

[0064] The salt solution was obtained by adding 90.79 g (1.03 mol) of butanediamine into 235 g of deionized water, and then slowly adding 146.14 g (1.0 mol) of adipic acid under mechanical stirring to carry out the salting reaction. The pH of the salt solution was 7.8, and the concentration was 40 wt%. Then, 0.0006 mol of the above complex catalyst was added into the salt solution, and after mixing uniformly, it was added into the polymerization kettle. After nitrogen replacement, the pressure was increased to 0.5 MPa, and the temperature was increased to 170°C to carry out the dehydration reaction of the salt solution, and the reaction time was 2 h. Then, the temperature was continuously increased to 220°C to carry out the prepolymerization reaction, the reaction pressure was 1.7 MPa, and the time was 2 h. Then, the temperature was continuously increased to 290°C to carry out the final polymerization reaction, the pressure was slowly released to normal pressure, and vacuum was extracted to an absolute pressure of 3.0 kPa A, and the time was 2.5 h. After the polymerization was completed, the melt discharge was carried out, and the polymer was transferred into water for rapid cooling, pelletizing to obtain the nylon 46 polymer.

[0065] Example 4

[0066] The complex catalyst was obtained by adding 0.1 mol of iron acetate and 0.2 mol of (R)-(+)-5,5'-bis(diphenylphosphino)-4,4'-di-1,3-benzodioxole into 500 mL of toluene, stirring under nitrogen protection at 120°C for 12 h, adding 300 mL of cyclohexane after cooling, and drying the precipitate.

[0067]

[0068] (R)-(+)-5,5'-bis(diphenylphosphino)-4,4'-di-1,3-benzodioxole

[0069] Put 92.56 g (1.05 mol) of butanediamine into 235 g of deionized water, then slowly add adipic acid 146.14 g (1.0 mol) under mechanical stirring to carry out the salt reaction to obtain a salt solution. The pH of the salt solution is 8.0 and the concentration is 50 wt%. Then add 0.001 mol of the above composite catalyst to the salt solution, mix well and then add to the polymerization kettle. After nitrogen replacement, pressurize to 0.5 MPa, heat to 180°C, and carry out the salt solution dehydration reaction for 2 h. Then continue to heat to 250°C to carry out the prepolymerization reaction, the reaction pressure is 1.0 MPa, and the time is 2 h. Then continue to heat to 320°C to carry out the final polymerization reaction, slowly depressurize to normal pressure, and vacuum to 1.0 kPaA absolute pressure for 1 h. After the polymerization is completed, melt discharge is carried out, and the polymer is transferred to water for rapid cooling, pelletizing to obtain nylon 46 polymer.

[0070] Example 5

[0071] Put 0.1 mol of copper acetate and 0.25 mol of R-(+)-2,2'-bis(diphenylphosphino)-1,1'-binaphthyl chiral phosphine ligand into 500 mL of toluene, stir under nitrogen protection at 90°C for 24 h, add 300 mL of cyclohexane after cooling, and obtain the composite catalyst after drying by precipitation.

[0072]

[0073] R-(+)-2,2'-bis(diphenylphosphino)-1,1'-binaphthyl

[0074] Put 89.03 g (1.01 mol) of butanediamine into 245 g of deionized water, then slowly add adipic acid 73.07 g (0.5 mol) and terephthalic acid 83.06 g (0.5 mol) under mechanical stirring to carry out the salt reaction to obtain a salt solution. The pH of the salt solution is 7.2 and the concentration is 50 wt%. Then add 0.0005 mol of the above composite catalyst to the salt solution, mix well and then add to the polymerization kettle. After nitrogen replacement, pressurize to 0.5 MPa, heat to 140°C, and carry out the salt solution dehydration reaction for 5 h. Then continue to heat to 200°C to carry out the prepolymerization reaction, the reaction pressure is 2.0 MPa, and the time is 4 h. Then continue to heat to 260°C to carry out the final polymerization reaction, slowly depressurize to normal pressure, and vacuum to 5.0 kPaA absolute pressure for 4 h. After the polymerization is completed, melt discharge is carried out, and the polymer is transferred to water for rapid cooling, pelletizing to obtain nylon 46 / 4T polymer.

[0075] Example 6

[0076] The 0.1 mol of copper acetate and 0.22 mol of R-(+)-2,2'-bis(diphenylphosphino)-1,1'-binaphthyl chiral phosphine ligand were added into 500 mL of toluene, and stirred at 100°C under nitrogen protection for 24 h. After cooling, 300 mL of cyclohexane was added, and the complex catalyst was obtained by drying the precipitate.

[0077]

[0078] R-(+)-2,2'-bis(diphenylphosphino)-1,1'-binaphthyl

[0079] The 96.96 g (1.1 mol) of butanediamine was added into 291 g of deionized water, and then the salt solution was obtained by slowly adding 202.25 g (1.0 mol) of sebacic acid under mechanical stirring. The pH of the salt solution was 8.5, and the concentration was 70 wt%. Then, 0.002 mol of the above complex catalyst was added into the salt solution, and the polymerization kettle was added after uniform mixing. After nitrogen replacement, the pressure was increased to 0.5 MPa, and the temperature was increased to 160°C. The salt solution dehydration reaction was carried out for 2 h. Then, the temperature was continuously increased to 200°C, the reaction pressure was 1.5 MPa, and the time was 2 h. Then, the temperature was continuously increased to 270°C, the pressure was slowly released to normal pressure, and the vacuum was extracted to 5.0 kPaA. The time was 2 h. After the polymerization was completed, the melt discharge was carried out, and the polymer was transferred to water for rapid cooling, pelletizing, and obtaining the nylon 410 polymer.

[0080] For the above examples 1-6 and comparative examples 1-3, the water content, the content of terminal carboxyl group, and the content of terminal amine group in the sample were determined by sampling at different reaction times. The salt solution dehydration reaction rate constant and the reaction activation energy, and the stage polymerization reaction rate constant and the reaction activation energy were calculated by combining the polymerization process reaction rate constant and the activation energy calculation method.

[0081] Then, the polymer viscosity was determined. The specific test method was as follows: 0.25 g of the sample was accurately weighed and added into 25 mL of concentrated sulfuric acid with a concentration of 96 wt%. After complete dissolution, the solution was placed in an Ubbelohde viscometer, and the falling speed (t) was measured after placing in a constant temperature bath at 25°C for 10 minutes. In addition, the falling speed (t0) of 96 wt% sulfuric acid was determined by the same method. The relative viscosity was calculated according to the following formula: relative viscosity = t / t0.

[0082] In addition, the distilled water was subjected to gas chromatography quantitative analysis, so as to determine the content of the byproduct tetrahydropyrrole.

[0083] The test results are shown in the following table:

[0084]

[0085]

[0086] As can be seen from the above examples and comparative examples, in the process for preparing high-temperature nylon polymer according to the present application, due to the space structure of the composite catalyst, the intramolecular cyclization side reaction of butanediamine can be blocked, the content of the by-product tetrahydropyrrole is significantly reduced, the reaction time is shortened, and the viscosity of the obtained polymer is significantly increased. The method of the present application only needs to add an appropriate amount of composite catalyst in the original high-temperature nylon salt formation reaction process, so that the nylon 46 polymer can be directly synthesized by one-step method. The method avoids the pre-polymerization and solid-phase tackification process in the traditional nylon polymerization process, and also avoids the powder material processing and modification process, greatly simplifying the process flow. Therefore, the present application is simple and easy to operate, can obtain nylon polymer with higher molecular weight and produce less by-product tetrahydropyrrole, has good economic benefit, is environment-friendly, and is suitable for industrial production.

[0087] The above only describes the preferred embodiments of the present application, and it should be pointed out that for ordinary skilled persons in the art, several improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A composite catalyst for nylon synthesis, characterized in that, It includes a metal salt and a chiral phosphine ligand; the chiral phosphine ligand is a chiral bidentate phosphine ligand with C2 symmetry; the composite catalyst has a six-coordinate octahedral structure with two active sites.

2. The composite catalyst as described in claim 1, characterized in that, The metal salt is one or more of copper acetate, zinc acetate, cobalt acetate, and ferric acetate; preferably copper acetate or zinc acetate.

3. The composite catalyst as described in claim 1, characterized in that, The chiral bidentate phosphine ligand is one or more of R-(+)-2,2'-bis(diphenylphosphine)-1,1'-binaphthyl, (R)-(+)-2,2'-bis[bis(3,5-dimethylphenyl)phosphine]-1,1'-binaphthyl, (R)-(+)-2,2′-bis(diphenylphosphine)-6,6′-dimethoxy-1,1′-biphenyl and (R)-(+)-5,5′-bis(diphenylphosphine)-4,4′-bis-1,3-benzodioxane.

4. A method for preparing a composite catalyst for nylon synthesis, characterized in that, The composite catalyst is the composite catalyst according to any one of claims 1 to 3, and the preparation method comprises the following steps: The metal salt and the chiral bidentate phosphine ligand were added to an organic solvent and mixed and reacted under inert gas protection. After the reaction was cooled, cyclohexane was added to obtain a precipitate. The precipitate was dried to obtain the composite catalyst.

5. The preparation method according to claim 4, characterized in that, The molar ratio of the metal salt to the chiral phosphine ligand is 1:2 to 1:2.5; preferably, the molar ratio is 1:2 to 1:2.

2. And / or, the organic solvent is one or a mixture of toluene, tetrahydrofuran and dioxane in any proportion, preferably toluene; And / or, the reaction temperature is 90-120℃; the reaction time is 12-24h.

6. A method for synthesizing nylon polymers based on butanediamine monomers, characterized in that, Includes the following steps: Step 1: Add butanediamine to deionized water, then add a diacid monomer to carry out a salt formation reaction to obtain a salt solution; Step 2: Add the composite catalyst according to any one of claims 1-3 or the composite catalyst prepared by the preparation method according to claim 4 or 5 to the obtained salt solution; Step 3: Subsequently, a staged polymerization reaction is carried out in a reactor to obtain the nylon polymer.

7. The synthesis method according to claim 6, characterized in that, In step 1, the molar ratio of the dicarboxylic acid monomer to butanediamine is 1:(1-1.1); preferably 1:(1-1.05). And / or, the salt solution has a pH of 7.1 to 8.5 and a concentration of 40 to 70 wt%.

8. The synthesis method as described in claim 6, characterized in that, In step 2, the molar ratio of the composite catalyst to the butanediamine is (0.5-5):1000, preferably (0.5-2):1000.

9. The synthesis method according to claim 6, characterized in that, In step 3, the staged polymerization reaction includes a salt solution dehydration reaction, a prepolymerization reaction, and a final polymerization reaction; And / or, the dehydration reaction temperature of the salt solution is 140–180°C, the pressure is 0.5–1.0 MPa, and the reaction time is 2–5 h; And / or, the prepolymerization reaction temperature is 200–250°C, the pressure is 1.0–2.0 MPa, and the reaction time is 2–4 h; And / or, the final polymerization reaction temperature is 260–320°C, the vacuum is drawn to an absolute pressure of 1.0–5.0 kPaA, and the reaction time is 1–4 h.

10. The nylon polymer synthesized by the method according to claim 6, characterized in that, The nylon polymer is nylon 46, nylon 4T, nylon 46 / 4T, nylon 410, or nylon 412.

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