CN114262302B - Method for synthesizing diisocyanate trimer, catalyst and preparation method thereof - Google Patents

Abstract

The invention discloses a method for synthesizing diisocyanate trimer, a catalyst and a preparation method thereof. The method for synthesizing the diisocyanate trimer comprises the steps of taking diisocyanate as a raw material, and carrying out polymerization reaction in the presence of a catalyst to obtain the diisocyanate trimer, wherein the catalyst comprises a supported ionic liquid, the carrier is a silicon-based mesoporous material, the ionic liquid is an organic guanidine salt ionic liquid, and the organic guanidine salt ionic liquid is chemically bonded on the carrier. The organic guanidine salt ionic liquid comprisesStructural unit and R ₆ ‑COO ^‑ The structural unit, the organic guanidine salt ionic liquid is chemically bonded on the carrier through the silane coupling agent. The synthesis method of the diisocyanate trimer has the advantages of low reaction temperature, good catalytic selectivity, high yield and capability of obtaining a transparent colorless diisocyanate trimer product with low viscosity.

Description

A method, catalyst and preparation method for synthesizing diisocyanate trimer

Technical field

The invention relates to a method for synthesizing diisocyanate trimer, a catalyst and a preparation method thereof.

Background technique

The demand for diisocyanates is large. For example, hexamethylene diisocyanate is the most important type of aliphatic diisocyanate, accounting for about 60% of the total demand for aliphatic diisocyanates. However, hexamethylene diisocyanate is highly volatile and toxic, and most of the hexamethylene diisocyanate monomers are further processed into hexamethylene diisocyanate polymers. Among them, the isocyanurate ring of hexamethylene diisocyanate trimer has a stable structure and is not easily decomposed at high temperatures. Therefore, it has the advantages of good thermal stability, good wear resistance, and good corrosion resistance, and is often used as Polyurethane curing agents are widely used in fields such as furniture, automobile industry, aviation industry and sports equipment.

For the reaction of synthesizing its trimer from diisocyanate, the selection of catalyst is more studied.

Qiu Shaojun et al. published a study on the synthesis of HDI trimers in the second issue of Volume 13 of "Polyurethane Industry" in 1998. An N-hydroxyalkyl quaternary ammonium base was used as the catalyst for the reaction. When the catalyst mass fraction was 0.3%, The NCO content of the obtained trimer was 23.11%, and the product yield was 31.12%. US patent US5235018 uses aromatic quaternary ammonium salts as catalysts, and the NCO content of the obtained trimer is 19%, and the yield is 49.1%. Zhang Jie et al. disclosed a method for preparing HDI trimers using quaternary ammonium carboxylates of different structures as catalysts in "Coating Industry" Volume 45, Issue 9, with a catalytic selectivity of about 53%. However, quaternary ammonium bases and quaternary ammonium salts have poor thermal stability and are easily decomposed at high temperatures. Moreover, the dispersion of the catalyst is not good. After being added to the reactor, they tend to aggregate into lumps, causing partial deactivation of the catalyst or excessive local concentration, ultimately leading to The reaction uniformity is not good, white gelatinous matter is easily produced, and the product is turbid.

US patent US5905151 discloses a lithium salt of an aliphatic or aromatic carboxylic acid as a catalyst, but the reaction temperature needs to be set to 125-250°C. The reaction temperature is too high and the product viscosity is large. In addition, the catalyst brings in metal ions. Affect the performance of trimer products.

U.S. Patent No. 4960848 discloses the use of quaternary ammonium fluoride as a catalyst. The catalyst is easy to completely remove, has low refining cost, and the trimer product prepared by the catalysis is light in color. However, the viscosity of the obtained product is high, and the viscosity of the product increases rapidly as the NCO content decreases. At the same time, the trimer product also has turbidity.

Contents of the invention

In view of the shortcomings and shortcomings of the existing technology, the present invention provides an improved method for synthesizing diisocyanate trimer, which can be carried out at low temperature, has good catalytic selectivity, and can obtain low viscosity, transparent and colorless of diisocyanate trimer products.

The present invention also provides a new type of catalyst used in the above-mentioned synthesis method of diisocyanate trimer. The catalyst has good thermal stability. When used in the above-mentioned synthesis method, it has good catalytic selectivity and the obtained trimer product is of high quality. The catalyst can be recycled and reused a high number of times, and the catalytic effect is still good after being reused several times.

In order to achieve the above objects, the technical solutions adopted by the present invention are as follows:

A method for synthesizing diisocyanate trimer. The method uses diisocyanate as a raw material and performs a polymerization reaction in the presence of a catalyst to obtain a diisocyanate trimer. The catalyst includes a supported ionic liquid, and the supported ion In the liquid, the carrier is a silicon-based mesoporous material, and the ionic liquid is an organic guanidine salt ionic liquid, and the organic guanidine salt ionic liquid is chemically bonded to the carrier.

Further, the silicon-based mesoporous material is one or a combination of more selected from MCM type molecular sieve, SBA type molecular sieve, HMS type molecular sieve, MSU type molecular sieve, ZSM type molecular sieve, KIT type molecular sieve and USY type molecular sieve;

Preferably, the silicon-based mesoporous material is one or a combination of more selected from the group consisting of MCM-41 molecular sieve, SBA-16 molecular sieve and HMS molecular sieve.

Further, the organic guanidine salt ionic liquid includes Structural unit and R ₆ -COO ^- structural unit, wherein R ₁ , R ₂ , R ₃ , R ₄ and R ₅ are each independently selected from H or C ₁ -C ₁₀ alkyl group, R ₆ -COO ^- is selected from C ₂ -C ₆ organic acid radicals;

Further preferably, R ₁ , R ₂ , R ₃ , R ₄ and R ₅ are each independently selected from H, CH ₃ , C ₂ H ₅ , C ₃ H ₇ , C ₄ H ₉ , C ₅ H ₁₁ or C ₆ H ₁₃ , R ₆ -COO ^- is selected from lactate, acetate, propionate, butyrate or isobutyrate.

In some embodiments of the present invention, the organic guanidine salt ionic liquid is chemically bonded to the carrier through a silane coupling agent. Preferably, the silane coupling agent is selected from 3-chloropropyltriethoxy silane, 3-chloropropyltrimethoxysilane, 2-chloroethyltriethoxysilane, 2-chloroethyltrimethoxysilane, 3-chloropropyldimethoxymethylsilane, 3-chloroethyltriethoxysilane of propyldiethoxymethylsilane, 2-chloroethylmethyldimethoxysilane, 2-chloromethyldimethylethoxysilane and 3-chloropropyldimethylethoxysilane One or a combination of more.

In some embodiments of the invention, the organic guanidine salt ionic liquid is selected from the group consisting of N,N,N',N'-tetramethylguanidine lactate ionic liquid, N,N,N',N',N" -Pentamethylguanidine acetate ionic liquid, N,N,N',N'-tetramethyl-N"-butylguanidine propionate ionic liquid and N,N'-dimethyl-N,N' - one or a combination of more than one of the diethylguanidine lactate ionic liquids.

The inventor found through research that the organic guanidine salt ionic liquid supported by the silicon-based mesoporous material through chemical bonding can be used as a catalyst for the diisocyanate trimer synthesis reaction, and after being supported by the silicon-based mesoporous material, especially through chemical bonding, The catalytic efficiency of the organic guanidine salt ionic liquid catalyst is increased, the catalytic selectivity is improved, and the viscosity of the trimer product is reduced and colorless. The three nitrogen atoms of the cations of the organic guanidine salt ionic liquid in the catalyst of the present invention are conjugated, and the positive charges are distributed on the three nitrogen atoms and the central carbon, so that the organic guanidine salt ionic liquid is in phase with the quaternary ammonium salt and the quaternary phosphorus salt. It has better thermal stability, and uses chemical bonding method to immobilize the ionic liquid onto the silicon-based mesoporous material through covalent bonds, making the combination between the ionic liquid and the silicon-based mesoporous material stronger, and the ionic liquid is not easy to fall off. , the prepared supported organic guanidine salt ionic liquid is more stable, has good reusability, and can be recycled and reused for a high number of times. At the same time, the organic guanidine salt ionic liquid is loaded between the pores of the silicon-based mesoporous material, thereby further improving the catalyst thermal stability. In addition, the organic guanidine salt ionic liquid in the catalyst has high catalytic activity, the reaction does not require high temperature, and the reaction conditions are mild.

In some embodiments of the present invention, the organic guanidine salt ionic liquid accounts for 5 to 30% of the mass of the catalyst, preferably 7 to 20%.

Further, the mass ratio of the catalyst to the diisocyanate is 0.01% to 5%, preferably 0.05% to 1%.

In some embodiments of the present invention, the diisocyanate is selected from aliphatic diisocyanate or aromatic diisocyanate, and the aliphatic diisocyanate is selected from the group consisting of hexamethylene diisocyanate, isophorone diisocyanate and 4 , a combination of one or more of 4-dicyclohexylmethane diisocyanate, the aromatic diisocyanate is selected from toluene diisocyanate, diphenylmethane diisocyanate, terephthalene diisocyanate, terephthalenedimethylene One or a combination of one or more of diisocyanate, dimethylbiphenyl diisocyanate and naphthalene diisocyanate.

In some embodiments of the present invention, the method for synthesizing diisocyanate trimer includes the following steps:

1) Add the diisocyanate and the catalyst into the reaction vessel;

2) Heat to the reaction temperature of 20-100°C, preferably 30-60°C, and react for 2-10 hours, preferably 3-8 hours. Then measure the -NCO content in the reaction solution. When the NCO content drops to 15% to 40%, add a terminator. terminate reaction;

3) After maintaining the temperature for a certain period of time, the reaction system is cooled down, the catalyst is filtered, and the obtained filtrate is separated by two-stage membrane distillation to obtain the diisocyanate trimer.

Further, the terminator is selected from one or more of benzoyl chloride, phosphoric acid, p-hexane sulfonate and dimethyl sulfate, preferably benzoyl chloride;

Further, the added mass of the terminator is 0.01% to 2% of the mass of the aliphatic diisocyanate, preferably 0.05% to 1%.

In some embodiments of the present invention, the holding time is 0.2 to 5 hours, preferably 0.5 to 2 hours.

In some embodiments of the present invention, in the two-stage membrane distillation separation, the first-level membrane separation pressure is 500-2000Pa and the temperature is 100-170°C, and the second-level membrane separation pressure is 50-1000Pa and the temperature is 100-170°C. 140℃.

Further, the filtered catalyst is recycled for reuse.

Preferably, the diisocyanate is selected from hexamethylene diisocyanate, and the reaction formula of the synthesis method is as follows:

The present invention also provides a preparation method of the aforementioned catalyst, which preparation method includes the following steps:

1) Use a silane coupling agent to surface modify the silicon-based mesoporous material to obtain a surface-modified silicon-based mesoporous material;

2) react organic guanidine with the surface-modified silicon-based mesoporous material to obtain an organic guanidine-modified silicon-based mesoporous material;

3) React the organic guanidine-modified silicon-based mesoporous material with an organic acid to obtain the catalyst.

Further, the structural formula of the organic guanidine is Wherein, R ₁ , R ₂ , R ₃ , R ₄ and R ₅ are each independently selected from H or C ₁ -C ₁₀ alkyl group. Preferably, R ₁ , R ₂ , R ₃ , R ₄ and R ₅ are each independently selected. Independently selected from H, CH ₃ , C ₂ H ₅ , C ₃ H ₇ , C ₄ H ₉ , C ₅ H ₁₁ or C ₆ H ₁₃ , the organic acid is selected from C ₂ -C ₆ organic acids, Preferably, the organic acid is selected from lactic acid, acetic acid, propionic acid, butyric acid or isobutyric acid.

In some embodiments of the invention, the silane coupling agent is selected from the group consisting of 3-chloropropyltriethoxysilane, 3-chloropropyltrimethoxysilane, 2-chloroethyltriethoxysilane, 2 -Chloroethyltrimethoxysilane, 3-chloropropyldimethoxymethylsilane, 3-chloropropyldiethoxymethylsilane, 2-chloroethylmethyldimethoxysilane, 2- One or more of chloromethyldimethylethoxysilane and 3-chloropropyldimethylethoxysilane.

In some embodiments of the present invention, the mass ratio of the silane coupling agent to the silicon-based mesoporous material is 0.5 to 2, preferably 0.8 to 1.2; and/or, the organic guanidine and the surface modification The mass ratio of the final silicon-based mesoporous material is 0.1-1, preferably 0.2-0.5; and/or the mass ratio of the organic acid to the organic guanidine-modified silicon-based mesoporous material is 0.05-0.5, preferably 0.1 ~0.3.

In some embodiments of the present invention, the step 1) is carried out in an organic solvent and under a nitrogen atmosphere, and the reaction is carried out at a temperature of 80 to 120°C for 4-8 hours. The organic solvent in step 1) is selected from chlorobenzene, toluene , a combination of one or more of xylene and ethyl acetate, preferably toluene; and/or, the step 2) is carried out in an organic solvent and under a nitrogen atmosphere, and the reaction is carried out at a temperature of 80 to 120°C for 15-35h, The organic solvent in step 2) is selected from one or more combinations of chlorobenzene, toluene, xylene and ethyl acetate, preferably toluene; and/or the step 3) is performed in an organic solvent, The reaction temperature is 15-35°C, the reaction time is 2-4 hours, and the organic solvent in step 3) is selected from one or more combinations of cyclohexane, ethanol, methanol, acetonitrile and acetone, preferably ethanol.

In some embodiments of the invention, the preparation method of the catalyst includes the following steps:

(1) Weigh a certain amount of 3-chloropropyltriethoxysilane and silicon-based mesoporous materials into the reaction bottle, add a certain amount of toluene as the reaction solvent, stir and react at 110°C for 4 to 8 hours under nitrogen protection , after the reaction is completed, cool and filter, then wash with dichloromethane. The product is vacuum dried at 100°C for 3 to 10 hours to obtain a surface-modified silicon-based mesoporous material. The reaction formula is as follows:

(2) Dissolve organic guanidine in toluene solution, add a certain amount of surface-modified silicon-based mesoporous material, stir and react at 95°C for 15 to 35 hours under nitrogen protection, filter after the reaction is completed, wash with ether several times, 80 After vacuum drying at ℃ for 4 to 8 hours, an organic guanidine-modified silicon-based mesoporous material is obtained. The reaction formula is as follows:

(3) Add the organic guanidine-modified silicon-based mesoporous material to a certain amount of ethanol and mix evenly, add a certain amount of organic acid dropwise, stir at room temperature for 2 to 4 hours, filter after the reaction is completed, and wash with ethanol for several times. times, vacuum drying at 100°C for 3 to 10 hours to obtain the catalyst. The reaction formula is as follows:

Compared with the existing technology, the present invention has the following advantages:

The diisocyanate trimer synthesis method of the present invention has low reaction temperature, good reaction selectivity and high yield, and can obtain a low viscosity, transparent and colorless diisocyanate trimer product.

The catalyst of the present invention has good thermal stability, high catalytic activity, high reaction selectivity for trimer synthesis, and does not require high temperature for the synthesis reaction; and has good dispersion and is not easy to adhere to the reaction kettle and stirring paddle during the reaction process. On the surface, the diisocyanate trimer product prepared using this catalyst has a low viscosity, is colorless and transparent, which significantly improves the quality of the trimer product; and the catalyst is easy to recycle and apply, and the catalytic performance has not been significantly reduced after being applied more than 20 times. .

Detailed ways

The present invention will be further described below in conjunction with examples. However, the present invention is not limited to the following examples. The implementation conditions used in the embodiments can be further adjusted according to different requirements for specific use. Unspecified implementation conditions are conventional conditions in the industry. The technical features involved in the various embodiments of the present invention can be combined with each other as long as they do not conflict with each other.

In the following examples, the loading amount of the catalyst =mass of active component/(mass of active component+mass of carrier)*100%.

Example 1

1) Preparation of N,N,N’,N’-tetramethylguanidine lactate ionic liquid catalyst supported by chemical bonding on MCM-41 molecular sieve

(1) Weigh 100g of 3-chloropropyltriethoxysilane and 100g of MCM-41 molecular sieve into the reaction bottle, add 500ml of toluene as the reaction solvent, stir and react at 110°C for 6 hours under nitrogen protection, and the reaction is completed , cool and filter, and then wash with dichloromethane. The product is vacuum dried at 100°C for 5 hours to obtain a surface-modified silicon-based mesoporous material.

(2) Dissolve 25g N,N,N',N'-tetramethylguanidine in 250ml toluene solution, add 100g surface-modified silicon-based mesoporous material, stir and react at 95°C for 26 hours under nitrogen protection, and react After completion, filter, wash with diethyl ether several times, and vacuum dry at 80°C for 4 hours to obtain an organic guanidine-modified silicon-based mesoporous material.

(3) Add the organic guanidine-modified silicon-based mesoporous material to 400 ml of ethanol, add 20 g of lactic acid dropwise, and stir at room temperature for 3 hours. After the reaction is completed, filter, wash with ethanol several times, and vacuum dry at 100°C for 5 hours to obtain 114.5g of N,N,N',N'-tetramethylguanidine lactate ionic liquid catalyst supported by MCM-41 molecular sieve through chemical bonding, and the loading capacity of the catalyst is 12.7%.

2) Synthesis of diisocyanate trimer

Add 1000g hexamethylene diisocyanate HDI and 5g of the above catalyst into the reaction vessel. Stir and heat under nitrogen protection to raise the temperature to 35°C. After 4 hours of reaction, measure the NCO content in the reaction solution to reduce to about 30%. Add 1g benzoyl chloride. The reaction was terminated, and after the reaction was continued for 0.5 h, the temperature was lowered to stop stirring, and the catalyst was filtered to obtain a transparent colorless liquid. The reaction liquid undergoes two-stage thin film distillation separation technology to obtain the HDI trimer product. The first-stage thin-film distillation separation pressure is 1000Pa and the temperature is 120°C. The second-stage thin-film distillation separation pressure is 100Pa and the temperature is 120°C.

Di-n-butylamine titration was used to determine the -NCO content in the product, liquid chromatography was used to analyze the free hexamethylene diisocyanate content in the sample, a viscometer was used to determine the product viscosity, and gel permeation chromatography was used to determine the catalytic selectivity. The calculation method is C _{catalytic selectivity} = W _{HDI trimer} /(W _{HDI trimer} + W _{HDI dimer} + W _{HDI multimer} ) * 100%, where W _{HDI trimer} , W _{HDI dimer} , W _{HDI multimer} is the quality of HDI trimer, HDI dimer and HDI multimer in the product respectively.

The NCO content of the final product was measured to be 23.5%, the HDI monomer content was 0.13%, the product viscosity was 1750 mPa·s, the product yield was 72.5%, and the catalytic selectivity was 65.5%.

Example 2

1) Preparation of N,N,N’,N’-tetramethylguanidine lactate ionic liquid catalyst supported by chemical bonding on HMS-type molecular sieves

(1) Weigh 100g of 3-chloropropyltriethoxysilane and 100g of HMS molecular sieve into the reaction bottle, add 500ml of toluene as the reaction solvent, stir and react at 110°C for 6 hours under nitrogen protection, after the reaction is completed, cool Filter, then wash with dichloromethane, and the product is vacuum dried at 100°C for 5 hours to obtain a surface-modified silicon-based mesoporous material.

(2) Dissolve 25g N,N,N',N'-tetramethylguanidine in 250ml toluene solution, add 100g of the above dry product, stir and react at 95°C for 26h under nitrogen protection, filter after the reaction is completed, and wash with ether After several times of vacuum drying at 80°C for 4 hours, an organic guanidine-modified silicon-based mesoporous material was obtained.

(3) Add the above product to 400 ml of ethanol, add 20 g of lactic acid dropwise, and stir at room temperature for 3 hours. After the reaction is completed, filter, wash with ethanol several times, and vacuum dry at 100°C for 5 hours to obtain an HMS molecular sieve loaded by chemical bonding. 113g of N,N,N',N'-tetramethylguanidine lactate ionic liquid catalyst, the catalyst loading is 11.5%.

2) Synthesis of diisocyanate trimer

Add 1000g hexamethylene diisocyanate HDI monomer and 5.75g of the above catalyst into the reaction vessel, stir and heat to 40°C under nitrogen protection, after 4 hours of reaction, measure the NCO content in the reaction solution to reduce to about 30%, add 1g The reaction was terminated by benzoyl chloride, and after the reaction was continued for 0.5 h, the temperature was lowered to stop stirring, and the catalyst was filtered to obtain a transparent colorless liquid. The reaction liquid undergoes two-stage thin film distillation separation technology to obtain the HDI trimer product. The first-stage thin-film distillation separation pressure is 1000Pa and the temperature is 120°C. The second-stage thin-film distillation separation pressure is 100Pa and the temperature is 120°C. The NCO content of the final product was determined to be 23.1%, the HDI monomer content was 0.15%, the product viscosity was 1870 mPa·s, the product yield was 70.5%, and the catalytic selectivity was 64.2%.

Example 3

1) Preparation of N,N,N’,N’-tetramethylguanidine lactate ionic liquid catalyst supported by chemical bonding on SBA-16 molecular sieve

(1) Weigh 100g of 3-chloropropyltriethoxysilane and 100g of SBA-16 molecular sieve into the reaction bottle, add 500ml of toluene as the reaction solvent, stir and react at 110°C for 6 hours under nitrogen protection, and the reaction is completed , cool and filter, and then wash with dichloromethane. The product is vacuum dried at 100°C for 5 hours to obtain a surface-modified silicon-based mesoporous material.

(2) Dissolve 25g N,N,N',N'-tetramethylguanidine in 250ml toluene solution, add 100g of the above dry product, stir and react at 95°C for 26h under nitrogen protection, filter after the reaction is completed, and wash with ether After several times of vacuum drying at 80°C for 4 hours, an organic guanidine-modified silicon-based mesoporous material was obtained.

(3) Add the above product to 400 ml of ethanol, add 20 g of lactic acid dropwise, stir at room temperature for 3 hours, filter after the reaction is completed, wash with ethanol several times, and vacuum dry at 100°C for 5 hours to obtain SBA-16 molecular sieve through chemical bonding The total supported N,N,N',N'-tetramethylguanidine lactate ionic liquid catalyst was 113.8g, and the catalyst loading was 12.1%.

2) Synthesis of diisocyanate trimer

Add 1000g HDI monomer and 5.2g of the above catalyst into the reaction vessel, stir and heat to 40°C under nitrogen protection. After 4 hours of reaction, measure the NCO content in the reaction solution to reduce to about 30%. Add 1g benzoyl chloride to terminate the reaction. After continuing the heat preservation reaction for 0.5 h, the temperature was lowered to stop stirring, and the catalyst was filtered to obtain a transparent colorless liquid. The reaction liquid undergoes two-stage thin film distillation separation technology to obtain HDI trimer products. The first-stage thin-film distillation separation pressure is 1kPa and the temperature is 120°C. The second-stage thin-film distillation separation pressure is 100Pa and the temperature is 120°C. The NCO content of the final product was determined to be 22.9%, the HDI monomer content was 0.15%, the product viscosity was 1930 mPa·s, the product yield was 68.5%, and the catalytic selectivity was 64.7%.

Example 4

1) Prepare MCM-41 type molecular sieve through chemical bonding supported N,N,N’,N’,N”-pentamethylguanidine acetate ionic liquid catalyst

(1) Weigh 100g of 3-chloropropyltriethoxysilane and 100g of MCM-41 molecular sieve into the reaction bottle, add 500ml of toluene as the reaction solvent, stir and react at 110°C for 6 hours under nitrogen protection, and the reaction is completed , cool and filter, and then wash with dichloromethane. The product is vacuum dried at 100°C for 5 hours to obtain a surface-modified silicon-based mesoporous material.

(2) Dissolve 25g N,N,N',N',N"-pentamethylguanidine in 250ml toluene solution, add 100g of the above dry product, stir and react at 95°C for 26h under nitrogen protection, filter after the reaction is completed, Washed with diethyl ether several times and dried under vacuum at 80°C for 4 hours, an organic guanidine-modified silicon-based mesoporous material was obtained.

(3) Add the above product to 400 ml of ethanol, add 20 g of acetic acid dropwise, stir at room temperature for 3 hours, filter after the reaction is completed, wash with ethanol several times, and vacuum dry at 100°C for 5 hours to obtain MCM-41 molecular sieve through chemical bonding The total supported N,N,N',N',N"-pentamethylguanidine acetate ionic liquid catalyst was 112g, and the loading of the catalyst was 10.7%.

2) Synthesis of diisocyanate trimer

Add 1000g HDI monomer and 6g MCM molecular sieve-loaded N,N,N',N',N"-pentamethylguanidine acetate ionic liquid catalyst into the reaction vessel, stir and heat to 40°C under nitrogen protection. , after 4 hours of reaction, measure the NCO content in the reaction solution to drop to about 30%. Add 1g of benzoyl chloride to terminate the reaction. After continuing to keep the reaction for 0.5 hours, cool down and stop stirring. Filter the catalyst to obtain a transparent colorless liquid. The reaction solution goes through two stages. Thin film distillation separation technology obtains HDI trimer products. The first-stage thin-film distillation separation pressure is 1000Pa and the temperature is 120°C. The second-stage thin-film distillation separation pressure is 100Pa and the temperature is 120°C. The NCO content of the final product is measured to be 23.3%. HDI The monomer content is 0.14%, the product viscosity is 1815mPa·s, the product yield is 69.8%, and the catalytic selectivity is 65.1%.

Example 5

1) Prepare MCM-41 type molecular sieve through chemical bonding supported N,N,N’,N’-tetramethyl-N”-butylguanidine propionate ionic liquid catalyst

(1) Weigh 100g of 3-chloropropyltriethoxysilane and 100g of MCM-41 molecular sieve into the reaction bottle, add 500ml of toluene as the reaction solvent, stir and react at 110°C for 6 hours under nitrogen protection, and the reaction is completed , cool and filter, then wash with dichloromethane, and the product is vacuum dried at 100°C for 5 hours. The surface-modified silicon-based mesoporous material was obtained.

(2) Dissolve 25g N,N,N',N'-tetramethyl-N"-butylguanidine in 250ml toluene solution, add 100g of the above dry product, stir the reaction at 95°C for 26h under nitrogen protection, and the reaction is completed After filtering, washing with diethyl ether several times, and vacuum drying at 80°C for 4 hours, an organic guanidine-modified silicon-based mesoporous material was obtained.

(3) Add the above product to 400 ml of ethanol, add 20 g of propionic acid dropwise, stir at room temperature for 3 hours, filter after the reaction is completed, wash with ethanol several times, and vacuum dry at 100°C for 5 hours to obtain MCM-41 molecular sieve passing 110.5g of chemically bonded supported N,N,N',N'-tetramethyl-N"-butylguanidine propionate ionic liquid catalyst, and the loading of the catalyst is 9.5%.

2) Synthesis of diisocyanate trimer

Add 1000g HDI monomer and 7.3g of the above catalyst into the reaction vessel, stir and heat to 40°C under nitrogen protection. After 4 hours of reaction, measure the NCO content in the reaction solution to reduce to about 30%. Add 1g benzoyl chloride to terminate the reaction. After continuing the heat preservation reaction for 0.5 h, the temperature was lowered to stop stirring, and the catalyst was filtered to obtain a transparent colorless liquid. The reaction liquid undergoes two-stage thin film distillation separation technology to obtain the HDI trimer product. The first-stage thin-film distillation separation pressure is 1000Pa and the temperature is 120°C. The second-stage thin-film distillation separation pressure is 100Pa and the temperature is 120°C. The NCO content of the final product is measured. It is 22.7%, the HDI monomer content is 0.15%, the product viscosity is 1960mPa·s, the product yield is 68.7%, and the catalytic selectivity is 63.9%.

Example 6

1) The catalyst preparation process is the same as in Example 1.

2) The synthesis process of diisocyanate trimer is as follows:

Add 1000g of isophorone diisocyanate IPDI into the reaction vessel, and 5g of the N,N,N',N'-tetramethylguanidine lactate ionic liquid catalyst supported by chemical bonding on the MCM-41 molecular sieve in Example 1, Stir and heat up to 35°C under nitrogen protection. After 4 hours of reaction, measure the NCO content in the reaction solution to drop to about 20%. Add 1g of benzoyl chloride to terminate the reaction. Continue the heat preservation reaction for 0.5 hours, then cool down and stop stirring. Filter the catalyst to obtain Transparent colorless liquid. The reaction liquid undergoes two-stage membrane distillation separation technology to obtain IPDI trimer products. The first-stage membrane distillation separation pressure is 1000Pa and the temperature is 145°C. The second-stage membrane distillation separation pressure is 100Pa and the temperature is 145°C.

The -NCO content in the product was determined by titration with di-n-butylamine, the free isophorone diisocyanate content in the sample was analyzed by liquid chromatography, the viscosity of the product was determined by a viscometer, the catalytic selectivity was determined by gel permeation chromatography, and the catalytic selectivity was calculated. The method is C _{catalytic selectivity} = W _{IPDI trimer} /(W _{IPDI trimer} + W _{IPDI dimer} + W _{IPDI multimer} ) * 100%, where W _{IPDI trimer} , W _{IPDI dimer} , W _{IPDI multimers} are the quality of IPDI trimers, IPDI dimers and IPDI multimers in the product respectively.

The NCO content of the final product was determined to be 17.5%, the IPDI monomer content was 0.2%, the product viscosity was 850 mPa·s, the product yield was 73.2%, and the catalytic selectivity was 73.5%.

Example 7

1) The catalyst preparation process is the same as in Example 1.

2) The synthesis process of diisocyanate trimer is as follows:

Add 1000g of toluene diisocyanate TDI and 5g of the MCM-41 molecular sieve in Example 1 through chemical bonding to the N,N,N',N'-tetramethylguanidine lactate ionic liquid catalyst in the reaction vessel, under nitrogen protection Stir and heat up to 35°C. After 4 hours of reaction, measure the NCO content in the reaction solution to drop to about 30%. Add 1g of benzoyl chloride to terminate the reaction. Continue the heat preservation reaction for 0.5 hours, then cool down and stop stirring. Filter the catalyst to obtain a transparent and colorless product. liquid. The reaction liquid undergoes two-stage thin film distillation separation technology to obtain the TDI trimer product. The first-stage thin-film distillation separation pressure is 1000Pa and the temperature is 115°C. The second-stage thin-film distillation separation pressure is 100Pa and the temperature is 115°C.

The -NCO content in the product was determined by titration with di-n-butylamine, the free isophorone diisocyanate content in the sample was analyzed by liquid chromatography, the viscosity of the product was determined by a viscometer, the catalytic selectivity was determined by gel permeation chromatography, and the catalytic selectivity was calculated. The method is C _{catalytic selectivity} = W _{TDI trimer} /(W _{TDI trimer} + W _{TDI dimer} + W _{TDI multimer} ) * 100%, where W _{TDI trimer} , W _{TDI dimer} , W _{TDI multimers} are the masses of TDI trimers, TDI dimers, and TDI multimers in the product respectively.

The NCO content of the final product was determined to be 22.0%, the TDI monomer content was 0.3%, the product viscosity was 2560 mPa·s, the product yield was 75.2%, and the catalytic selectivity was 64.7%.

Example 8

1) Preparation of N,N’-dimethyl-N,N’-diethylguanidine lactate ionic liquid catalyst supported by chemical bonding on MCM-41 molecular sieve

(1) Weigh 100g of 2-chloroethyltrimethoxysilane and 100g of MCM-41 molecular sieve into the reaction bottle, add 500ml of toluene as the reaction solvent, stir and react at 110°C for 6 hours under nitrogen protection, and the reaction is completed. Cool and filter, then wash with dichloromethane. The product is vacuum dried at 100°C for 5 hours to obtain a surface-modified silicon-based mesoporous material.

(2) Dissolve 25g N,N'-dimethyl N,N'-diethylguanidine in 250ml toluene solution, add 100g surface-modified silicon-based mesoporous material, and stir the reaction at 95°C under nitrogen protection. 26h, filter after the reaction is completed, wash with diethyl ether several times, and vacuum dry at 80°C for 4h to obtain an organic guanidine-modified silicon-based mesoporous material.

(3) Add the organic guanidine-modified silicon-based mesoporous material to 400 ml of ethanol, add 20 g of lactic acid dropwise, and stir at room temperature for 3 hours. After the reaction is completed, filter, wash with ethanol several times, and vacuum dry at 100°C for 5 hours to obtain 112.5g of N,N'-dimethyl N,N'-diethylguanidine lactate ionic liquid catalyst supported by MCM-41 molecular sieve through chemical bonding, and the loading amount of the catalyst is 10%.

2) Synthesis of diisocyanate trimer

Add 1000g hexamethylene diisocyanate HDI and 6.35g of the above catalyst into the reaction vessel, stir and heat to 35°C under nitrogen protection, after 4 hours of reaction, measure the NCO content in the reaction solution to reduce to 30%, add 1g benzoyl chloride The reaction was terminated, and after the reaction was continued for 0.5 h, the temperature was lowered to stop stirring, and the catalyst was filtered to obtain a transparent colorless liquid. The reaction liquid undergoes two-stage thin film distillation separation technology to obtain the HDI trimer product. The first-stage thin-film distillation separation pressure is 1000Pa and the temperature is 120°C. The second-stage thin-film distillation separation pressure is 100Pa and the temperature is 120°C.

Di-n-butylamine titration was used to determine the -NCO content in the product, liquid chromatography was used to analyze the free hexamethylene diisocyanate content in the sample, a viscometer was used to determine the product viscosity, and gel permeation chromatography was used to determine the catalytic selectivity. The calculation method is C _{catalytic selectivity} = W _{HDI trimer} /(W _{HDI trimer} + W _{HDI dimer} + W _{HDI multimer} ) * 100%, where W _{HDI trimer} , W _{HDI dimer} , W _{HDI multimer} is the quality of HDI trimer, HDI dimer and HDI multimer in the product respectively.

The NCO content of the final product was measured to be 22.8%, the HDI monomer content was 0.15%, the product viscosity was 1850 mPa·s, the product yield was 69.7%, and the catalytic selectivity was 63.5%.

Comparative example 1

Add 1000g HDI monomer and 0.64g N,N,N',N'-tetramethylguanidine lactate ionic liquid catalyst into the reaction vessel. Stir and heat under nitrogen protection to raise the temperature to 35°C. After 4 hours of reaction, measure the reaction. The NCO content in the liquid was reduced to about 30%. 1g of benzoyl chloride was added to terminate the reaction. After the reaction was continued for 0.5 hours, the temperature was lowered and stirring was stopped to obtain a light yellow liquid. The reaction liquid was subjected to two-stage membrane distillation and separation technology to obtain the HDI trimer product. The first-stage thin film distillation separation pressure is 1000Pa and the temperature is 120°C. The second-stage thin film distillation separation pressure is 100Pa and the temperature is 120°C. The NCO content of the final product is 18.5%, the HDI monomer content is 0.15%, and the product viscosity is 3580mPa· s, the product yield is 54.3%, and the catalytic selectivity is 48.5%, indicating that the guanidine salt ionic liquid catalyst without molecular sieve support has low catalytic efficiency, poor catalytic selectivity, high viscosity, and yellow color.

Comparative example 2

The MCM-41 molecular sieve in the catalyst in this comparative example does not support ionic liquid through chemical bonding, but supports ionic liquid through physical adsorption.

1) Preparation of N,N,N’,N’-tetramethylguanidine lactate ionic liquid catalyst supported by physical adsorption on MCM-41 molecular sieve

(1) Dissolve 25g N,N,N',N'-tetramethylguanidine in 250ml toluene solution, add 100g MCM-41 molecular sieve, stir and react at 95°C for 26h under nitrogen protection, filter after the reaction is completed, and use After washing with diethyl ether several times and vacuum drying at 80°C for 4 hours, an organic guanidine-modified silicon-based mesoporous material was obtained.

(2) Add the organic guanidine-modified silicon-based mesoporous material to 400 ml of ethanol, add 20 g of lactic acid dropwise, stir at room temperature for 3 hours, filter after the reaction is completed, wash with ethanol several times, and vacuum dry at 100°C for 5 hours to obtain MCM-41 type molecular sieve supports 109.5g of N,N,N',N'-tetramethylguanidine lactate ionic liquid catalyst through physical adsorption, and the loading capacity of the catalyst is 8.7%.

2) Synthesis of diisocyanate trimer

Add 1000g hexamethylene diisocyanate HDI and 7.3g of the above catalyst into the reaction vessel. Stir and heat under nitrogen protection to raise the temperature to 35°C. After 6 hours of reaction, measure the NCO content in the reaction solution to reduce to about 30%. Add 1g of benzene. The acid chloride terminated the reaction, and after continuing the heat preservation reaction for 0.5 h, the temperature was lowered to stop stirring, and the catalyst was filtered to obtain a transparent colorless liquid. The reaction liquid undergoes two-stage thin film distillation separation technology to obtain the HDI trimer product. The first-stage thin-film distillation separation pressure is 1000Pa and the temperature is 120°C. The second-stage thin-film distillation separation pressure is 100Pa and the temperature is 120°C.

Di-n-butylamine titration was used to determine the -NCO content in the product, liquid chromatography was used to analyze the free hexamethylene diisocyanate content in the sample, a viscometer was used to determine the product viscosity, and gel permeation chromatography was used to determine the catalytic selectivity. The calculation method is C _{catalytic selectivity} = W _{HDI trimer} /(W _{HDI trimer} + W _{HDI dimer} + W _{HDI multimer} ) * 100%, where W _{HDI trimer} , W _{HDI dimer} , W _{HDI multimer} is the quality of HDI trimer, HDI dimer and HDI multimer in the product respectively.

The NCO content of the final product was determined to be 19.2%, the HDI monomer content was 0.15%, the product viscosity was 2860 mPa·s, the product yield was 61.2%, and the catalytic selectivity was 54.5%.

Example 9

Catalyst application experiment:

The MCM-41 type molecular sieve filtered out in Example 1 was used to carry out an application experiment through a chemically bonded N,N,N',N'-tetramethylguanidine lactate ionic liquid catalyst. The data are as shown in Table 1 below. Specifically The steps for catalytically synthesizing diisocyanate trimer are the same as those in Example 1. It can be seen that the catalyst of the present invention can be used repeatedly for many times, and the catalytic activity will not be significantly reduced after being used multiple times.

Table 1

The above embodiments are only for illustrating the technical concepts and characteristics of the present invention. Their purpose is to enable those familiar with this technology to understand the content of the present invention and implement it accordingly. They cannot limit the scope of protection of the present invention. All equivalent changes or modifications made based on the spirit of the present invention should be included in the protection scope of the present invention.

The endpoints of ranges and any values disclosed herein are not limited to the precise range or value, but these ranges or values are to be understood to include values approaching such ranges or values. For numerical ranges, the endpoint values of each range, the endpoint values of each range and individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges. These values The scope shall be deemed to be specifically disclosed herein.

Claims (21)

1. A method for synthesizing diisocyanate trimer, which takes diisocyanate as raw material and carries out polymerization reaction in the presence of catalyst, is characterized in that: the catalyst is a supported ionic liquid, wherein in the supported ionic liquid, a carrier is a silicon-based mesoporous material, the ionic liquid is an organic guanidine salt ionic liquid, and the organic guanidine salt ionic liquid is chemically bonded on the carrier; the organic guanidine salt ionic liquid is chemically bonded to the carrier through a silane coupling agent; the organic guanidine salt ionic liquid is prepared from

Structural unit and R ₆ -COO ^- Structural unit composition, wherein R ₁ 、R ₂ 、R ₃ 、R ₄ 、R ₅ Each independently selected from H or C ₁ -C ₁₀ Alkyl of (a); the R is ₆ -COO ^- Selected from lactate, acetate, propionate, butyrate or isobutyrate; the silicon-based mesoporous material is selected from one or a combination of a plurality of MCM type molecular sieves, SBA type molecular sieves, HMS type molecular sieves, MSU type molecular sieves, ZSM type molecular sieves, KIT type molecular sieves and USY type molecular sieves.

2. The method for synthesizing a diisocyanate trimer according to claim 1, characterized in that: the silicon-based mesoporous material is selected from one or a combination of a plurality of MCM-41 type molecular sieves, SBA-16 type molecular sieves and HMS type molecular sieves.

3. The method for synthesizing a diisocyanate trimer according to claim 1, characterized in that: the R is ₁ 、R ₂ 、R ₃ 、R ₄ 、R ₅ Each independently selected from H, CH ₃ 、C ₂ H ₅ 、C ₃ H ₇ 、C ₄ H ₉ 、C ₅ H ₁₁ Or C ₆ H ₁₃ 。

4. The method for synthesizing a diisocyanate trimer according to claim 1, characterized in that: the silane coupling agent is selected from one or more of 3-chloropropyl triethoxysilane, 3-chloropropyl trimethoxysilane, 2-chloroethyl triethoxysilane, 2-chloroethyl trimethoxysilane, 3-chloropropyl dimethoxy methylsilane, 3-chloropropyl diethoxymethylsilane, 2-chloroethyl methyldimethoxy silane, 2-chloromethyl dimethylethoxy silane and 3-chloropropyl dimethylethoxy silane.

5. A process for the synthesis of a diisocyanate trimer according to claim 1 or 3, characterised in that: the organic guanidine salt ionic liquid is selected from one or a combination of more of N, N, N ', N' -tetramethyl guanidine lactate ionic liquid, N, N, N ', N', N '-pentamethyl guanidine acetate ionic liquid, N, N, N', N '-tetramethyl-N' -butyl guanidine propionate ionic liquid and N, N '-dimethyl-N, N' -diethyl guanidine lactate ionic liquid.

6. The method for synthesizing a diisocyanate trimer according to claim 1, characterized in that: the organic guanidine salt ionic liquid accounts for 5-30% of the mass of the catalyst; and/or the mass ratio of the catalyst to the diisocyanate is 0.01-5%.

7. The method for synthesizing a diisocyanate trimer according to claim 1, characterized in that: the organic guanidine salt ionic liquid accounts for 7-20% of the mass of the catalyst; and/or the mass ratio of the catalyst to the diisocyanate is 0.05-1%.

8. The method for synthesizing a diisocyanate trimer according to claim 1, characterized in that: the diisocyanate is selected from aliphatic diisocyanate or aromatic diisocyanate, the aliphatic diisocyanate is selected from one or a combination of more than one of hexamethylene diisocyanate, isophorone diisocyanate and 4, 4-dicyclohexylmethane diisocyanate, and the aromatic diisocyanate is selected from one or a combination of more than one of toluene diisocyanate, diphenylmethane diisocyanate, terephthalene diisocyanate, dimethylbiphenyl diisocyanate and naphthalene diisocyanate.

9. The method for synthesizing a diisocyanate trimer according to claim 1, characterized in that: the method comprises the following steps:

1) Adding the diisocyanate and the catalyst to a reaction vessel;

2) Heating to the reaction temperature of 20-100 ℃, measuring the-NCO content in the reaction liquid after the reaction is carried out for 2-10 hours, and adding a terminator to terminate the reaction when the-NCO content is reduced to 15-40%;

3) And after the heat preservation is carried out for a certain time, the temperature of the reaction system is reduced, the catalyst is filtered, and the obtained filtrate is subjected to two-stage thin film distillation separation to obtain the diisocyanate trimer.

10. The method of synthesizing a diisocyanate trimer according to claim 9, characterized in that: and 2) heating to the reaction temperature of 30-60 ℃, measuring the-NCO content in the reaction liquid after the reaction is carried out for 3-8 hours, and adding a terminator to terminate the reaction when the-NCO content is reduced to 15% -40%.

11. The method of synthesizing a diisocyanate trimer according to claim 9, characterized in that: the terminator is selected from one or more of benzoyl chloride, phosphoric acid, p-hexanesulfonate and dimethyl sulfate; the addition mass of the terminator is 0.01% -2% of the mass of the diisocyanate.

12. The method of synthesizing a diisocyanate trimer according to claim 9, characterized in that: the terminator is benzoyl chloride; the addition mass of the terminator is 0.05-1% of the mass of the diisocyanate.

13. The method of synthesizing a diisocyanate trimer according to claim 9, characterized in that: the heat preservation time is 0.2-5 h; and/or, in the two-stage membrane distillation separation, the primary membrane separation pressure is 500-2000 Pa, the temperature is 100-170 ℃, the secondary membrane separation pressure is 50-1000 Pa, and the temperature is 100-150 ℃.

14. The method of synthesizing a diisocyanate trimer according to claim 9, characterized in that: the heat preservation time is 0.5-2 h.

15. A catalyst as claimed in any one of claims 1 to 14.

16. A method for preparing the catalyst of claim 15, wherein: the preparation method comprises the following steps:

1) Carrying out surface modification on the silicon-based mesoporous material by adopting a silane coupling agent to obtain a surface-modified silicon-based mesoporous material;

2) Reacting organic guanidine with the silicon-based mesoporous material subjected to surface modification to obtain the silicon-based mesoporous material modified by the organic guanidine;

3) Reacting the organic guanidine modified silicon-based mesoporous material with organic acid to obtain the catalyst; the structural formula of the organic guanidine isWherein R is ₁ 、R ₂ 、R ₃ 、R ₄ 、R ₅ Each independently selected from H or C ₁ -C ₁₀ Alkyl of (a); the organic acid is selected from lactic acid, acetic acid, propionic acid, butyric acid or isobutyric acid.

17. The method for preparing a catalyst according to claim 16, wherein: the R is ₁ 、R ₂ 、R ₃ 、R ₄ 、R ₅ Each independently selected from H, CH ₃ 、C ₂ H ₅ 、C ₃ H ₇ 、C ₄ H ₉ 、C ₅ H ₁₁ Or C ₆ H ₁₃ The method comprises the steps of carrying out a first treatment on the surface of the And/or the silane coupling agent is selected from 3-chloropropyl triethoxysilane, 3-chloropropyl trimethoxysilane, 2-chloroethyl triethoxysilane, 2-chloroethyl trimethoxysilane, 3-chloropropyl dimethoxy methylsilane, 3-chloropropylOne or more of the group of diethoxymethylsilane, 2-chloroethyl methyldimethoxysilane, chloromethyldimethylethoxysilane and 3-chloropropyldimethylethoxysilane.

18. The method for preparing a catalyst according to claim 16, wherein: the mass ratio of the silane coupling agent to the silicon-based mesoporous material is 0.5-2; and/or the mass ratio of the organic guanidine to the surface-modified silicon-based mesoporous material is 0.1-1; and/or the mass ratio of the organic acid to the organic guanidine modified silicon-based mesoporous material is 0.05-0.5.

19. The method for preparing the catalyst according to claim 16, wherein: the mass ratio of the silane coupling agent to the silicon-based mesoporous material is 0.8-1.2; and/or the mass ratio of the organic guanidine to the surface-modified silicon-based mesoporous material is 0.2-0.5; and/or the mass ratio of the organic acid to the organic guanidine modified silicon-based mesoporous material is 0.1-0.3.

20. The method for preparing a catalyst according to claim 16, wherein: the step 1) is carried out in an organic solvent and under the nitrogen atmosphere, the reaction is carried out for 4-8 hours at the temperature of 80-120 ℃, and the organic solvent in the step 1) is selected from one or more of chlorobenzene, toluene, xylene and ethyl acetate; and/or, the step 2) is carried out in an organic solvent and under nitrogen atmosphere, the reaction is carried out for 15-35 hours at the temperature of 80-120 ℃, and the organic solvent in the step 2) is selected from one or more of chlorobenzene, toluene, xylene and ethyl acetate; and/or, the step 3) is carried out in an organic solvent, the reaction temperature is 15-35 ℃, the reaction time is 2-4h, and the organic solvent in the step 3) is selected from one or more of cyclohexane, ethanol, methanol, acetonitrile and acetone.

21. The method for preparing a catalyst according to claim 20, wherein: the organic solvent in the step 1) is toluene; and/or, the organic solvent in the step 2) is toluene; and/or, the organic solvent in the step 3) is ethanol.