Catalyst and preparation method thereof, and preparation method of aliphatic isocyanate polymer

Abstract

The present invention relates to a catalyst and a preparation method thereof and a preparation method of an aliphatic isocyanate polymer. The catalyst is a quaternary ammonium salt derived from an aza-macrocycloalkane, and is mainly used for preparing an aliphatic isocyanate polymer. The quaternary ammonium salt derived from the aza-macrocycloalkane is selected from at least one of a quaternary ammonium salt derived from a triaza-macrocycloalkane or a quaternary ammonium salt derived from a tetraaza-macrocycloalkane, and the nitrogen atom in the aza-macrocycloalkane-derived quaternary ammonium salt is expressed as follows: wherein R1 is selected from C3-C 10 The catalyst of the present invention is simple, efficient and low-cost. The catalyst is used to prepare aliphatic isocyanate polymers, and aliphatic isocyanate polymers with high trimer content can be obtained while ensuring low free monomer content.

Description

Technical Field

[0001] The invention relates to the technical field of isocyanate, in particular to a catalyst and a preparation method thereof and a preparation method of an aliphatic isocyanate polymer. Background Art

[0002] Although the reactivity of aliphatic isocyanates is not as good as that of aromatic isocyanates, since aliphatic isocyanates do not contain unsaturated groups such as aromatic rings, the coatings, adhesives and elastomers prepared using them have excellent weather resistance and yellowing resistance. Therefore, aliphatic isocyanates have been widely used in the preparation of yellowing-resistant polyurethane products. However, their own toxicity and volatility also bring many restrictions to their direct use. Therefore, in practical applications, they are usually converted into polymers with low free monomer content and stable isocyanurate ring structure. Among them, the ratio between trimers and penta-, hepta-, nona-, and polymers is an important indicator to measure whether a product is qualified.

[0003] At present, isocyanate polymers with a high trimer content can be prepared by reducing the reaction conversion rate. For example, patent US4801663 describes a preparation method with a narrow product distribution and a high trimer content, wherein the trimer content reaches about 70%-75%, but its reaction conversion rate is only 12%-21%, which inevitably leads to a large amount of unreacted free isocyanate monomers remaining. In order to obtain qualified products, these large amounts of monomers can only be removed by thin film evaporation, which undoubtedly greatly increases the production energy consumption.

[0004] In order to solve this dilemma, the direct synthesis method came into being. Compared with thin film evaporation, the direct synthesis method not only greatly reduces energy consumption, but also avoids a series of problems arising from the monomer recovery and application process. For example, patent GB949253 prepares TDI trimer by direct synthesis under the co-catalysis of alkaline metal carboxylates and N-substituted carbamates, but the monomer content in the product is as high as 1.25%, and it is necessary to introduce additional phase transfer catalysts or surfactants to increase the solubility of metal carboxylates, which undoubtedly increases the complexity of the catalytic system. Patent DE1201992 also has unqualified monomer content in the product prepared by direct synthesis, and the alkane-substituted phosphorus catalyst itself is a highly toxic substance, and it is easy to explode when exposed to air, which poses a considerable safety hazard in the production process. Patent US4115373 can prepare products with qualified monomer content by direct synthesis through the designed Mannich base type high-efficiency catalyst, but because the catalyst activity is too high, although the problem of monomer content is solved, the disadvantage of high polymer content in the synthesized product cannot be avoided.

[0005] Obviously, if the monomer content is reduced simply by continuous polymerization, the trimer content will be low and the five, seven, nine, and polymer content will be high, which will lead to the low NCO value and large viscosity of the product, and the compatibility of the product and the resin will also be deteriorated. In order to overcome this shortcoming, patents CN105964301A and CN108499606A have designed a series of metal palladium complex catalysts, which are modified by catalysts to have certain steric hindrance, and the steric effect is used to promote the reaction between small molecules, while suppressing the reaction between macromolecules and small molecules or macromolecules, and obtaining products with excellent molecular weight distribution. However, noble metal palladium is used in the preparation process of metal palladium complex catalysts and the preparation process is relatively complicated, which undoubtedly increases production costs.

[0006] Through the above analysis of the prior art, it can be found that how to design and prepare a simple, efficient and low-cost catalyst so that it can obtain an aliphatic isocyanate polymer with a high trimer content while ensuring a low free monomer content has become a difficult problem that needs to be overcome urgently in this technical field. Summary of the invention

[0007] Based on this, it is necessary to provide a catalyst and a preparation method thereof to address the above problems. The catalyst is simple, efficient and low-cost. By using the catalyst to prepare aliphatic isocyanate polymers, aliphatic isocyanate polymers with a high trimer content can be obtained while ensuring a low free monomer content.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is: a catalyst for preparing an aliphatic isocyanate polymer, wherein the catalyst is a quaternary ammonium salt derived from an aza-macrocycloalkane, wherein the quaternary ammonium salt derived from the aza-macrocycloalkane is selected from at least one of a quaternary ammonium salt derived from a triaza-macrocycloalkane or a quaternary ammonium salt derived from a tetraaza-macrocycloalkane, and the nitrogen atom in the aza-macrocycloalkane-derived quaternary ammonium salt is expressed as follows:

[0009]

[0010] Wherein R1 is selected from C3-C 10 An alkane or aromatic hydrocarbon, R2 is selected from a hydrocarbon group.

[0011] In one embodiment, the catalyst is selected from at least one of a quaternary ammonium salt derived from a triazamacrocycloalkane having a structural formula as shown in formula (1) to formula (3) or a quaternary ammonium salt derived from a tetraazamacrocycloalkane having a structural formula as shown in formula (4) to formula (5);

[0012]

[0013] Wherein, X is selected from halogen elements.

[0014] In one embodiment, R1 is selected from benzyl, isopropyl, and tert-butyl;

[0015] And / or, R2 is selected from methyl;

[0016] And / or, X is selected from bromine.

[0017] The present invention also provides a method for preparing a catalyst, comprising the following steps:

[0018] A mixture is formed by mixing an aza-macrocycloalkane with a weakly basic catalyst, an alkyl halide, and a solvent, wherein the aza-macrocycloalkane is selected from at least one of a triaza-macrocycloalkane or a tetraaza-macrocycloalkane, and the chemical formula of the alkyl halide is RX, and R is C3-C 10 Alkanes or aromatic hydrocarbons; X is a halogen element;

[0019] The mixture is heated to react, and after the reaction is completed, the reaction liquid is filtered to collect the filtrate;

[0020] The solvent in the filtrate is removed to obtain a quaternary ammonium salt derived from aza-macrocycloalkane.

[0021] In one embodiment, the molar ratio of aza-macrocyclic alkane, weakly basic catalyst and alkyl halide in the mixture is 32:(50-250):(90-300).

[0022] In one embodiment, the step of heating the mixture to react is specifically: reflux the mixture at 50° C.-150° C. for 8 hours-72 hours.

[0023] In one embodiment, the aza-macrocycloalkane is selected from at least one of 1,4,7-trimethyl-1,4,7-triazacyclononane, 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane, and 1,4,7,10-tetramethyl-1,4,7,10-tetraazacyclododecane;

[0024] And / or, the alkyl halide is selected from at least one of benzyl bromide, p-methyl benzyl bromide, methyl bromide, ethyl bromide, propyl bromide, 2-propyl bromide, 1-bromo-2-methylpropane, tert-butyl bromide, 2-butyl bromide, 2-butyl bromide, 1-bromo-3-methylbutane, 1-bromo-3,3-dimethylbutane, pentyl bromide, 2-butyl bromide, 3-butyl bromide, 1-bromo-4-methylpentane, hexyl bromide, 2-butyl bromide and bromomethylcyclohexane.

[0025] In one embodiment, the alkyl halide is selected from at least one of benzyl bromide, 2-bromopropane, and tert-butyl bromide.

[0026] The present invention also provides a method for preparing an aliphatic isocyanate polymer, wherein the preparation method is carried out in the presence of the catalyst.

[0027] In one embodiment, the preparation method comprises:

[0028] The catalyst is diluted with an organic solvent, and then added in batches to an aliphatic isocyanate monomer at 60° C. to 85° C. under a protective atmosphere, and the temperature is maintained for reaction, wherein the mass of the catalyst is 7000 ppm to 12000 ppm of the mass of the aliphatic isocyanate monomer;

[0029] The mass fraction of free NCO groups during the reaction is detected. When the mass fraction of free NCO groups is between 20% and 25%, a terminator is added to stop the reaction to obtain an aliphatic isocyanate polymer.

[0030] The quaternary ammonium salt derived from triazamacrocycloalkane and the quaternary ammonium salt derived from tetraazamacrocycloalkane have multiple nitrogen atom active sites at the same time, and thus have high catalytic activity. At the same time, the present invention can generate certain steric hindrance by introducing the R1 group on the nitrogen atom, thereby utilizing its own ring structure and the steric hindrance effect of the introduced group R1, so that when the quaternary ammonium salt derived from triazamacrocycloalkane or the quaternary ammonium salt derived from tetraazamacrocycloalkane is used as a catalyst to prepare an aliphatic isocyanate polymer, trimers can be selectively synthesized, and the reaction between macromolecules and small molecules or between macromolecules to produce penta-, hepta-, nona-, and multimers can be suppressed, thereby being able to obtain an aliphatic isocyanate polymer with a high trimer content while ensuring a low free monomer content, and the product composition distribution is excellent.

[0031] In addition, the catalyst of the present invention is essentially a quaternary ammonium salt, which is simple to synthesize and does not contain any precious metal, thereby greatly reducing the production cost. DETAILED DESCRIPTION

[0032] For ease of understanding of the present invention, the present invention will be described in more detail below. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the embodiments or examples described herein. On the contrary, the purpose of providing these embodiments or examples is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific implementation methods or embodiments, and are not intended to limit the present invention. The optional scope of the term "and / or" used herein includes any one of two or more related listed items, and also includes any and all combinations of related listed items, and the combinations include any two related listed items, any more related listed items, or all related listed items.

[0034] The catalyst provided by the present invention is mainly used for preparing aliphatic isocyanate polymers, and the catalyst is a quaternary ammonium salt derived from an aza-macrocycloalkane, wherein the quaternary ammonium salt derived from the aza-macrocycloalkane is selected from at least one of a quaternary ammonium salt derived from a triaza-macrocycloalkane or a quaternary ammonium salt derived from a tetraaza-macrocycloalkane, and the expression form at the nitrogen atom in the aza-macrocycloalkane-derived quaternary ammonium salt is as follows:

[0035]

[0036] Wherein R1 is selected from C3-C 10 An alkane or aromatic hydrocarbon, R2 is selected from a hydrocarbon group.

[0037] It can be understood that in the expression form at the nitrogen atom, the other two chemical bonds connected to the nitrogen atom are bonds for ring formation. In addition, the salt-forming element of the quaternary ammonium salt can be a halogen anion, such as F - , Cl - Br - ,I - , or it can be an acid radical, such as HSO4 - ,RCOO - In the present invention, the salt-forming element of the quaternary ammonium salt derived from triazamacrocycloalkane or tetraazamacrocycloalkane is preferably a halogen anion.

[0038] The quaternary ammonium salt derived from triazamacrocycloalkane and the quaternary ammonium salt derived from tetraazamacrocycloalkane have multiple nitrogen atom active sites at the same time, so they have high catalytic activity. At the same time, the present invention can produce certain steric hindrance by introducing R1 group on the nitrogen atom, thereby utilizing its own cyclic structure and the steric hindrance effect of the introduced group R1, so that when the quaternary ammonium salt derived from triazamacrocycloalkane or the quaternary ammonium salt derived from tetraazamacrocycloalkane is used as a catalyst to prepare aliphatic isocyanate polymers, trimers can be selectively synthesized, and the reaction between macromolecules and small molecules or macromolecules to produce penta, hepta, nona, and multimers can be suppressed, thereby obtaining aliphatic isocyanate polymers with higher trimer content under the premise of ensuring low free monomer content, and the product composition distribution is excellent. In addition, the catalyst of the present invention is essentially a quaternary ammonium salt, does not contain any precious metal, and greatly reduces the production cost.

[0039] Specifically, when the quaternary ammonium salt derived from triazamacrocycloalkane or tetraazamacrocycloalkane is used as a catalyst to prepare an aliphatic isocyanate polymer, the residual amount of free monomers is less than 0.2wt%. Therefore, the monomer separation step can be omitted, the process is simplified and the production cost is reduced; at the same time, a series of problems generated in the monomer recovery and reuse process can be avoided.

[0040] Among the aza-macrocycloalkanes, representative ones include 1,4,7-triazacyclononane, 1,4,8,11-tetraazacyclotetradecane, 1,4,7,10-tetraazacyclododecane, etc. The quaternary ammonium salt derived from the triaza-macrocycloalkane of the present invention is preferably obtained by reacting 1,4,7-triazacyclononane, and the quaternary ammonium salt derived from the tetraaza-macrocycloalkane is preferably obtained by reacting 1,4,8,11-tetraazacyclotetradecane or 1,4,7,10-tetraazacyclododecane.

[0041] Optionally, the catalyst is selected from at least one of a quaternary ammonium salt derived from a triazamacrocycloalkane having a structural formula as shown in formula (1) to formula (3) or a quaternary ammonium salt derived from a tetraazamacrocycloalkane having a structural formula as shown in formula (4) to formula (5);

[0042]

[0043]

[0044] Wherein, X is selected from halogen elements, preferably chlorine, bromine or iodine.

[0045] It can be understood that the present invention does not limit the structural formula of the quaternary ammonium salts derived from triazamacrocycloalkanes and tetraazamacrocycloalkanes. For example, the quaternary ammonium salts derived from triazamacrocycloalkanes with structural formulas such as formula (1) to formula (3) are all quaternary ammonium salts derived from 1,4,7-triazacyclononane. Although the structural formulas are different, the effects are basically the same.

[0046] When the quaternary ammonium salt derived from triazamacrocycloalkane or tetraazamacrocycloalkane is used as a catalyst to prepare aliphatic isocyanate polymer, the catalytic activity can be regulated by adjusting the R1 group.

[0047] Optionally, R1 is further selected from benzyl, isopropyl, tert-butyl; and / or, R2 is selected from methyl; and / or, X is selected from bromine.

[0048] The present invention also provides a method for preparing a catalyst, comprising the following steps:

[0049] S11, mixing an aza-macrocycloalkane with a weakly basic catalyst, an alkyl halide, and a solvent to form a mixture, wherein the aza-macrocycloalkane is selected from at least one of a triaza-macrocycloalkane or a tetraaza-macrocycloalkane, the alkyl halide has a chemical formula of RX, and R is C3-C 10 Alkanes or aromatic hydrocarbons; X is a halogen element;

[0050] S12, heating the mixture to react, filtering the reaction solution after the reaction is completed, and collecting the filtrate;

[0051] S13, removing the solvent in the filtrate to obtain a quaternary ammonium salt derived from an aza-macrocycloalkane.

[0052] In step S11, the molar ratio of the aza-macrocyclic alkane, the weakly basic catalyst and the alkyl halide in the mixture is preferably 32:(50-250):(90-300), and more preferably 32:(100-200):(100-250).

[0053] Among them, the aza-macrocycloalkane is preferably at least one of 1,4,7-trimethyl-1,4,7-triazacyclononane, 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane, and 1,4,7,10-tetramethyl-1,4,7,10-tetraazacyclododecane.

[0054] The alkyl halide is preferably at least one of benzylic bromide, p-methyl benzylic bromide, methyl bromide, ethyl bromide, propyl bromide, 2-propyl bromide, 1-bromo-2-methylpropane, tert-butyl bromide, 2-butyl bromide, 2-butyl bromide, 1-bromo-3-methylbutane, 1-bromo-3,3-dimethylbutane, pentyl bromide, 2-butyl bromide, 3-butyl bromide, 1-bromo-4-methylpentane, hexyl bromide, 2-butyl bromide and bromomethylcyclohexane, and more preferably at least one of benzylic bromide, 2-propyl bromide and tert-butyl bromide.

[0055] The weakly alkaline catalyst is selected from carbonates of alkali metals / alkaline earth metals, preferably potassium carbonate. The weak alkalinity of potassium carbonate can promote the reaction and neutralize the generated hydrogen halide.

[0056] In addition, the preparation method of the present invention is not limited to the solvent, preferably acetonitrile, and the amount used is 50mL-500mL.

[0057] In step S12, the step of heating the mixture to react is specifically: reflux the mixture at 50°C-150°C for 8 hours-72 hours, preferably, reflux the mixture at 60°C-100°C for 12 hours-36 hours.

[0058] In step S13, the method for removing the solvent in the filtrate can be selected from the reduced pressure distillation method.

[0059] Therefore, the preparation method of the catalyst of the present invention is simple, and the quaternary ammonium salt derived from aza-macrocycloalkane can be synthesized in one-step reaction, which is also beneficial to reducing the cost of preparing aliphatic isocyanate polymers.

[0060] The present invention also provides a method for preparing an aliphatic isocyanate polymer, wherein the preparation method is carried out in the presence of the catalyst.

[0061] Optionally, the preparation method comprises:

[0062] S21, diluting the catalyst with an organic solvent, and then adding the catalyst in batches to an aliphatic isocyanate monomer at 60° C. to 85° C. under a protective atmosphere, and maintaining the temperature for reaction, wherein the mass of the catalyst is 7000 ppm to 12000 ppm of the mass of the aliphatic isocyanate monomer;

[0063] S22, detecting the mass fraction of free NCO groups during the reaction process, and when the mass fraction of free NCO groups is between 20% and 25%, adding a terminator to stop the reaction, thereby obtaining an aliphatic isocyanate polymer.

[0064] In step S21, the organic solvent used to dilute the catalyst is preferably at least one of acetonitrile, acetone, and 2-ethyl-1,3-hexanediol, and more preferably 2-ethyl-1,3-hexanediol. The aliphatic isocyanate monomer is selected from at least one of isophorone diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, and lysine diisocyanate, and preferably hexamethylene diisocyanate.

[0065] In step S21, the temperature is further preferably 60°C-80°C, and more preferably 60°C-75°C.

[0066] In step S22, the terminator is preferably at least one of phosphoric acid, benzoyl chloride, and p-benzoic acid, more preferably benzoyl chloride, and the molar amount of the terminator is preferably equal to the molar amount of the catalyst.

[0067] Hereinafter, the catalyst and the preparation method thereof and the preparation method of the aliphatic isocyanate polymer will be further described through the following specific examples.

[0068] Catalyst Preparation Example 1

[0069] 1,4,7-Trimethyl-1,4,7-triazacyclononane (32mmol, 5.48g) was dissolved in 100mL acetonitrile, followed by the addition of K2CO3 (100mmol, 13.81g) and benzyl bromide (100mmol, 17.11g) to obtain a mixture. The mixture was then refluxed at 100°C for 24h and cooled to room temperature. The generated KBr and excess K2CO3 were filtered out, and the filter cake was rinsed three times with dichloromethane. The filtrate was collected and dried by adding anhydrous Na2SO4, and the solvent was finally removed by distillation under reduced pressure to obtain 1,4,7-trimethyl-1,4,7-tribenzyl-1,4,7-triazacyclononane quaternary ammonium salt catalyst with a yield of 87%.

[0070] 1 HNMR (400MHz, CD3CN): δppm 7.14 (m, 6H), 7.07 (m, 9H), 4.50 (s, 6H), 3.68 (t, J = 7.6Hz, 12H), 3.30 (s, 9H). ESI / MS:m / z=604.17,[M-Br] + .

[0071] The reaction equation is as follows:

[0072]

[0073] Catalyst Preparation Example 2

[0074] 1,4,7-Trimethyl-1,4,7-triazacyclononane (32mmol, 5.48g) was dissolved in 100mL acetonitrile, followed by the addition of K2CO3 (100mmol, 13.81g) and 2-bromopropane (100mmol, 12.19g) to obtain a mixture. The mixture was then refluxed at 100°C for 24h and cooled to room temperature. The generated KBr and excess K2CO3 were filtered out, and the filter cake was rinsed three times with dichloromethane. The filtrate was collected and dried by adding anhydrous Na2SO4, and the solvent was finally removed by distillation under reduced pressure to obtain 1,4,7-trimethyl-1,4,7-triisopropyl-1,4,7-triazacyclononane quaternary ammonium salt catalyst with a yield of 83%.

[0075] 1 HNMR (400MHz, CD3CN): δppm 3.92 (m, 3H), 3.71 (t, J = 8.1Hz, 12H), 3.32 (s, 9H), 1.30 (s, 18H). ESI / MS:m / z=460.16,[M-Br] + .

[0076] The reaction equation is as follows:

[0077]

[0078] Catalyst Preparation Example 3

[0079] 1,4,7-Trimethyl-1,4,7-triazacyclononane (32mmol, 5.48g) was dissolved in 100mL acetonitrile, followed by the addition of K2CO3 (100mmol, 13.81g) and tert-butyl bromide (100mmol, 13.59g) to obtain a mixture. The mixture was then refluxed at 100°C for 24h and cooled to room temperature. The generated KBr and excess K2CO3 were filtered out, and the filter cake was rinsed three times with dichloromethane. The filtrate was collected and dried by adding anhydrous Na2SO4, and the solvent was finally removed by distillation under reduced pressure to obtain 1,4,7-trimethyl-1,4,7-tri-tert-butyl-1,4,7-triazacyclononane quaternary ammonium salt catalyst with a yield of 79%.

[0080] 1 HNMR (400MHz, CD3CN): δppm 3.67 (t, J=7.8Hz, 12H), 3.31 (s, 9H), 1.35 (s, 27H). ESI / MS:m / z=502.22,[M-Br] + .

[0081] The reaction equation is as follows:

[0082]

[0083] Catalyst Preparation Example 4

[0084] 1,4,8,11-Tetramethyl-1,4,8,11-tetraazacyclotetradecane (32mmol, 8.20g) was dissolved in 100mL acetonitrile, followed by the addition of K2CO3 (100mmol, 13.81g) and benzyl bromide (135mmol, 17.01g) to obtain a mixture. The mixture was then refluxed at 100°C for 24 hours and then cooled to room temperature. The generated KBr and excess K2CO3 were filtered out, and the filter cake was rinsed three times with dichloromethane or chloroform. The filtrate was collected and dried by adding anhydrous Na2SO4, and the solvent was finally removed by distillation under reduced pressure to obtain 1,4,8,11-tetramethyl-1,4,8,11-tetrabenyl-1,4,8,11 tetraazacyclotetradecane quaternary ammonium salt catalyst with a yield of 89%.

[0085] 1 HNMR (400MHz, CD3CN): δppm 7.15(m,8H),7.06(m,12H),4.52(s,8H),3.64(t,J=8.5Hz,8H),3.28(s,12H),3.23(t,J=8.0Hz,8H),2.15(dt,J=7.8,2.5Hz,4H). ESI / MS:m / z=859.23,[M-Br] + .

[0086] The reaction equation is as follows:

[0087]

[0088] Catalyst Preparation Example 5

[0089] 1,4,8,11-Tetramethyl-1,4,8,11-tetraazacyclotetradecane (32mmol, 8.20g) was dissolved in 100mL acetonitrile, followed by the addition of K2CO3 (100mmol, 13.81g) and 2-bromopropane (135mmol, 16.47g) to obtain a mixture. The mixture was then refluxed at 100°C for 24 hours and then cooled to room temperature. The generated KBr and excess K2CO3 were filtered out, and the filter cake was rinsed three times with dichloromethane or chloroform. The filtrate was collected and dried by adding anhydrous Na2SO4, and the solvent was finally removed by distillation under reduced pressure to obtain 1,4,8,11-tetramethyl-1,4,8,11-tetraisopropyl-1,4,8,11 tetraazacyclotetradecane quaternary ammonium salt catalyst with a yield of 81%.

[0090] 1HNMR (400MHz, CD3CN): δppm 3.93 (m, 4H), 3.70 (t, J = 8.3Hz, 8H), 3.29 (s, 12H), 3.22 (t, J = 7.6Hz, 8H), 2.18 (dt, J = 8.0, 2.3Hz, 4H), 1.31 (s, 24H). ESI / MS:m / z=667.23,[M-Br] + .

[0091]

[0092] Catalyst Preparation Example 6

[0093] 1,4,8,11-Tetramethyl-1,4,8,11-tetraazacyclotetradecane (32mmol, 8.20g) was dissolved in 100mL acetonitrile, followed by the addition of K2CO3 (100mmol, 13.81g) and tert-butyl bromide (135mmol, 18.36g) to obtain a mixture. The mixture was then refluxed at 100°C for 24 hours and then cooled to room temperature. The generated KBr and excess K2CO3 were filtered off, and the filter cake was rinsed three times with dichloromethane or chloroform. The filtrate was collected and dried by adding anhydrous Na2SO4, and finally the solvent was removed by distillation under reduced pressure to obtain 1,4,8,11-tetramethyl-1,4,8,11-tetra-tert-butyl-1,4,8,11 tetraazacyclotetradecane quaternary ammonium salt catalyst with a yield of 83%.

[0094] 1 HNMR (400MHz, CD3CN): δppm 3.68 (t, J = 8.1 Hz, 8H), 3.30 (s, 12H), 3.24 (t, J = 7.4 Hz, 8H), 2.17 (dt, J = 8.2, 2.4 Hz, 4H), 1.35 (s, 36H). ESI / MS:m / z=721.29,[M-Br] + .

[0095] The reaction equation is as follows:

[0096]

[0097] Aliphatic isocyanate polymer preparation example 1

[0098] Under the protection of nitrogen, hexamethylene diisocyanate was added to a four-necked flask, stirred and heated to 65°C and stabilized for 15 minutes. Then, the 1,4,7-trimethyl-1,4,7-tribenzyl-1,4,7-triazacyclononane quaternary ammonium salt obtained in Catalyst Preparation Example 1 was diluted to 0.4wt% with 2-ethyl-1,3-hexanediol and then added dropwise to the four-necked flask, and the reaction temperature was maintained at 65°C for heat preservation and stirring until the mass fraction of free NCO groups was measured to be 23%, and then benzoyl chloride equal to the molar amount of the catalyst was added to terminate the reaction, and the material was filtered and discharged after heat preservation and stirring for 1h to obtain an aliphatic isocyanate polymer.

[0099] The NCO value, viscosity, chromaticity, residual HDI monomer content and trimer content of the obtained product were tested, and the results are shown in Table 1.

[0100] Aliphatic Isocyanate Polymer Preparation Examples 2-14

[0101] Aliphatic isocyanate polymer preparation examples 2-14 were carried out with reference to example 1, except for the selection of catalysts and reaction conditions, as shown in Table 1.

[0102] Comparative Examples 1-3 of Preparation of Aliphatic Isocyanate Polymers

[0103] Aliphatic isocyanate polymer preparation Comparative Examples 1-3 were carried out with reference to Example 1, except that the selection of catalysts and reaction conditions were different, as shown in Table 1, wherein the catalyst of Comparative Example 1 was tetramethylammonium chloride, the catalyst of Comparative Example 2 was tetraethylammonium chloride, and the catalyst of Comparative Example 3 was benzyltriethylammonium chloride, all of which were quaternary ammonium salts.

[0104] Table 1

[0105]

[0106]

[0107] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0108] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A catalyst for preparing an aliphatic isocyanate polymer, characterized in that: The catalyst is a quaternary ammonium salt derived from an aza-macrocycloalkane, wherein the aza-macrocycloalkane-derived quaternary ammonium salt is selected from at least one of a triaza-macrocycloalkane-derived quaternary ammonium salt having a structural formula as shown in formula (1) or a tetraaza-macrocycloalkane-derived quaternary ammonium salt having a structural formula as shown in formula (4) to formula (5); 、 、 ； Wherein R1 is selected from C3-C 10 An alkane or benzyl group, R2 is selected from a methyl group, and X is selected from a halogen element.

2. The catalyst according to claim 1, characterized in that R1 is selected from one of benzyl, isopropyl and tert-butyl; And / or, X is selected from bromine.

3. A method for preparing the catalyst according to claim 1, characterized in that: The following steps are involved: A mixture is formed by mixing an aza-macrocyclic alkane with a weakly basic catalyst, R1-X, and a solvent, wherein the aza-macrocyclic alkane is selected from at least one of 1,4,7-trimethyl-1,4,7-triazacyclononane, 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane, and 1,4,7,10-tetramethyl-1,4,7,10-tetraazacyclododecane, and R1 in R1-X is C3-C 10 An alkane or benzyl group, X is a halogen element; The mixture is heated to react, and after the reaction is completed, the reaction liquid is filtered to collect the filtrate; The solvent in the filtrate is removed to obtain a quaternary ammonium salt derived from an aza-macrocycloalkane.

4. The method for preparing the catalyst according to claim 3, characterized in that: The molar ratio of the aza-macrocyclic alkane, the weakly basic catalyst and R1-X in the mixture is 32: (50-250): (90-300).

5. The method for preparing the catalyst according to claim 3, characterized in that: The step of heating the mixture to react is specifically: placing the mixture under reflux at 50° C.-150° C. for 8 hours-72 hours.

6. The method for preparing the catalyst according to any one of claims 3 to 5, characterized in that: The R1-X is selected from at least one of benzyl bromide, bromopropane, 2-bromopropane, 1-bromo-2-methylpropane, tert-butyl bromide, 2-bromobutane, 2-bromo-3-methylbutane, 1-bromo-3,3-dimethylbutane, bromopentane, 2-bromopentane, 3-bromopentane, 1-bromo-4-methylpentane, bromohexane, and 2-bromohexane.

7. The method for preparing a catalyst according to claim 6, characterized in that: The R1-X is selected from at least one of benzyl bromide, 2-bromopropane and tert-butyl bromide.

8. A method for preparing an aliphatic isocyanate polymer, characterized in that: The preparation method comprises: The catalyst as claimed in any one of claims 1 to 2 is diluted with an organic solvent, and then added in batches to an aliphatic isocyanate monomer at 60° C. to 85° C. under a protective atmosphere, and the temperature is maintained for reaction; The mass fraction of free NCO groups during the reaction was detected. When the mass fraction of free NCO groups was between 20% and 25%, a terminator was added to stop the reaction and obtain an aliphatic isocyanate polymer.

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