Alicyclic diisocyanate as well as preparation method and application thereof

Abstract

The invention provides alicyclic diisocyanate as well as a preparation method and application thereof. The alicyclic diisocyanate has a structure as shown in a formula I in the specification. The alicyclic diisocyanate adopts a specific structural design, and has the advantages of low viscosity, high curing speed, high hardness of the prepared material and the like; moreover, the alicyclic diisocyanate is simple in preparation process and low in cost, and the alicyclic isocyanate tripolymer prepared from the alicyclic diisocyanate does not contain volatile isocyanate and meets the requirements of greenness and environmental protection.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of organic chemical industry, and particularly relates to a cycloaliphatic diisocyanate, a preparation method and application thereof. BACKGROUND

[0002] Isocyanate is a core raw material for preparing polyurethane, and its molecular structure and properties have a decisive influence on the performance of the final polyurethane material. Aliphatic isocyanate has fewer unsaturated bonds in its structure, and the polyurethane material prepared therefrom has excellent anti-aging, light resistance and yellowing resistance, and also exhibits good mechanical properties, and is therefore widely used in the fields of high-performance coatings, elastomers and sealants. However, aliphatic isocyanate has a slow drying speed, and exhibits certain deficiencies in applications requiring high mechanical strength and hardness.

[0003] In comparison, cycloaliphatic diisocyanate, due to its special cyclic structure, combines the advantages of aliphatic and aromatic isocyanate, and can provide a faster curing speed, low viscosity, high hardness and excellent wear resistance. For example, isophorone diisocyanate (IPDI) belongs to high-end cycloaliphatic diisocyanate, and is generally used for manufacturing light-resistant and weather-resistant polyurethane coatings and hydrolysis-resistant polyurethane elastomers. However, the production cost of isophorone diisocyanate is high, and the process is relatively complex, and the curing speed and the hardness of the prepared coating still need to be further improved.

[0004] Therefore, it is an urgent problem to be solved in the field to develop a cycloaliphatic diisocyanate with low viscosity, fast curing speed, high hardness of the prepared coating, simple preparation process and low cost. SUMMARY

[0005] In view of the deficiencies in the prior art, the present application aims to provide a cycloaliphatic diisocyanate, a preparation method and application thereof. The cycloaliphatic diisocyanate has high reactivity due to the isocyanate group being connected to the methylene on the alicyclic ring, and has the advantages of fast curing speed, short drying time, low viscosity, no yellowing and the like, and the product prepared therefrom has high hardness.

[0006] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0007] In a first aspect, the present application provides a cycloaliphatic diisocyanate, which has the structure shown in Formula I:

[0008]

[0009] In Formula I, R1 and R2 are each independently selected from a single bond or a C1-C6 straight-chain or branched-chain alkylene group.

[0010] In the present invention, the alicyclic diisocyanate adopts a specific structural design and has the advantages of low viscosity, fast curing speed, and high hardness of the prepared material. In addition, the preparation process of the alicyclic diisocyanate is simple and low-cost, and the alicyclic isocyanate trimer prepared from the alicyclic diisocyanate does not contain volatile isocyanate, which meets the requirements of green environmental protection.

[0011] Preferably, R1 and R2 are not simultaneously selected from single bonds.

[0012] In the present invention, R1 and R2 are both selected from single bonds, which is not conducive to improving the curing speed and reducing the viscosity.

[0013] Preferably, R1 and R2 are each independently selected from C1-C6 straight or branched alkylene groups, and the difference in the number of carbon atoms between R1 and R2 is ≥1, for example, it can be 1, 2, 3, 4, 5, etc.

[0014] In the present invention, the C1-C6 straight chain or branched alkylene group can be, for example, C1, C2, C3, C4, C5, or C6 straight chain or branched alkylene group; illustratively including but not limited to methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, neopentyl, n-hexyl, etc.

[0015] Preferably, R1 and R2 are each independently selected from a single bond or a C1-C4 straight chain or branched alkylene group.

[0016] Preferably, the alicyclic diisocyanate is selected from any one of the following compounds.

[0017]

[0018] In the present invention, the alicyclic diisocyanate has a specific structure, so that the alicyclic diisocyanate is used as a curing agent to effectively reduce the viscosity of the system, increase the curing speed and obtain a product with high hardness.

[0019] In a second aspect, the present invention provides a method for preparing the alicyclic diisocyanate according to the first aspect, the preparation method comprising the following steps:

[0020] (1) reacting an alicyclic diamine with a carbonate to obtain a carbamate;

[0021] (2) subjecting the carbamate obtained in step (1) to a thermal decomposition reaction to obtain the alicyclic diisocyanate; the alicyclic diamine has a structure shown in Formula II: In formula II, R1 and R2 are selected from the same range as in formula I.

[0022] In the present application, the preparation method first prepares the carbamate, and then uses the thermal cracking method to prepare the alicyclic diisocyanate, which does not need to use phosgene in the preparation process, avoids the high toxicity and high corrosivity of the phosgene method for preparing the alicyclic diisocyanate, and the by-product is alcohol which can be recycled, such as being used for producing carbonates; in addition, the raw materials are widely sourced and low in cost, such as the alicyclic diamine which can be sourced from existing commercially available products, or can be sourced from the cyclic by-products generated in the production process of adipic acid or mixed alkanes, which not only can turn waste into treasure, reduce the emission of by-products, and improve the added value of by-products, but also can broaden the types and applications of alicyclic diisocyanates, which is conducive to the sustainable development of green chemical industry; and the alicyclic diamine raw material has a low melting point and does not need to be dissolved with a solvent, and the intermediate product carbamate does not need to be rectified, but can be precipitated by adding water, which is simple to operate and has high yield and purity.

[0023] In the present application, the preparation route of the alicyclic diisocyanate is as follows.

[0024]

[0025] wherein, R 21 , R 22 are selected from the same range as R1 and R2.

[0026] Preferably, the molar ratio of the alicyclic diamine to the carbonate in step (1) is <1, for example, it can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.8, 0.9, etc.

[0027] In the present application, the carbonate includes but is not limited to dimethyl carbonate, diethyl carbonate, dipropyl carbonate, etc.

[0028] Preferably, the raw material of the reaction in step (1) further includes a catalyst A.

[0029] Preferably, the mass of the catalyst A is 2-13% of the mass of the alicyclic diamine, for example, it can be 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, etc.

[0030] Preferably, the catalyst A includes a Lewis acid.

[0031] Preferably, the Lewis acid includes at least one of manganese acetate, cerium nitrate, magnesium nitrate, magnesium acetate, chromium acetate, cobalt nitrate, cobalt acetate, zinc nitrate, and zinc acetate.

[0032] Preferably, the temperature of the reaction in step (1) is 30-90℃, for example, it can be 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, etc.; the time is 2-20h, for example, it can be 2h, 4h, 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, etc.

[0033] Preferably, after the reaction in step (1), a post-treatment step is further included; the post-treatment includes filtration, precipitation and drying in sequence.

[0034] In the present application, the method of precipitation includes: adding distilled water to the filtrate obtained by filtration, standing, and precipitating crystals; the volume of the distilled water is 5-20 times the volume of the filtrate, for example, it can be 5 times, 6 times, 8 times, 10 times, 12 times, 14 times, 16 times, 18 times, 20 times, etc.

[0035] Preferably, the thermal cracking reaction in step (2) is carried out in a solvent.

[0036] Preferably, the content of the solvent is such that the mass concentration of the carbamate is 0.05-10%, for example, it can be 0.05%, 0.1%, 0.2%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 3%, 3.2%, 3.5%, 3.8%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 9.9%, etc.

[0037] In the present application, the content of the solvent is such that the mass concentration of the carbamate is within the above range, which can reduce the contact between the reactant carbamate and the product alicyclic diisocyanate, and improve the purity of the product; and in order to reduce the generation of side reactions, it should be carried out at a specific temperature.

[0038] In the present application, the solvent is selected from low-boiling organic solvents.

[0039] Preferably, the solvent includes at least one of xylene, m-xylene, o-xylene, chlorobenzene or o-dichlorobenzene.

[0040] Preferably, the raw material of the thermal cracking reaction in step (2) further includes a catalyst B.

[0041] Preferably, the mass of the catalyst B is 1-10% of the mass of the carbamate, for example, it can be 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 3%, 3.2%, 3.5%, 3.8%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 9.9%, etc.

[0042] Preferably, the catalyst B comprises a supported heterogeneous catalyst.

[0043] Preferably, the catalyst B comprises at least one of supported cobalt trioxide, supported cobalt tetraoxide, supported molybdenum oxide, supported cobalt oxide, supported manganese oxide, or supported zinc oxide.

[0044] Preferably, the support of the catalyst B comprises mesoporous titanium dioxide and / or silica nanospheres.

[0045] Preferably, the loading of the catalyst B is 10-30wt%, for example, it can be 10wt%, 12wt%, 15wt%, 18wt%, 20wt%, 22wt%, 25wt%, 28wt%, 30wt%, etc.

[0046] In the present application, the catalyst B is a heterogeneous catalyst, and mesoporous titanium dioxide or silica nanospheres are used as the catalyst support, which takes full advantage of the high specific surface area, large pore volume, and ordered mesoporous pore structure, which is beneficial to the following effects: first, the high specific surface area enables the active component catalyst to be fully loaded on the surface of the support and uniformly distributed, thereby increasing the loading and tightness. Second, the reaction liquid is in close contact with the reaction liquid in the mesoporous channel, which significantly improves the reaction efficiency. Third, as a heterogeneous catalyst, it is easy to separate, avoiding the problem of catalyst residue after reaction; in addition, it can be repeatedly used, reducing the consumption of catalyst.

[0047] In the present application, the support used by the catalyst B can be commercially available or prepared by existing methods (such as sol-gel method, template method), exemplarily, the method comprises but is not limited to the following steps:

[0048] (a) using a block copolymer EO 20 PO 70 EO 20(P123) was used as a structure directing agent, ethyl orthosilicate was used as a silicon source or butyl titanate was used as a titanium source, and 0.5M hydrochloric acid was used for catalysis. Then, P123, silicon source / titanium source and hydrochloric acid were added to anhydrous ethanol, stirred at room temperature to obtain a transparent sol, which was then poured into a watch glass for solvent evaporation until it became a transparent gel. The obtained dry gel was then calcined in a muffle furnace at 600°C for 6 to 7h (heating rate of 1.5°C / min) to obtain a mesoporous carrier with a highly ordered mesoporous structure, with a specific surface area and pore size of 337m, respectively. 2 / g, 4.2nm.

[0049] (b) Mesoporous nanospheres were prepared using amphiphilic block copolymer PS-b-PAA and hexadecyl ammonium bromide (CTAB) as dual templates. First, PS-b-PAA was added to tetrahydrofuran, dissolved by half at room temperature, and then quickly poured into an alkaline solution containing CTAB, ultrapure water and ammonia. Subsequently, the mixed solution was stirred at 35°C for 30 minutes, and after adding a silicon source or a titanium source, it was stirred overnight. The obtained sample was centrifuged, washed, dried, and then calcined in a muffle furnace at 550°C for 6-8 hours (heating rate of 1°C / min) to obtain the mesoporous titanium dioxide or silicon dioxide nanospheres, i.e., catalyst carriers. The specific surface area of ​​the catalyst carrier is 550m 2 / g, pore size is 12.3nm, and average particle size is 200nm.

[0050] In the present invention, the preparation method of the catalyst B includes: ultrasonically dispersing the catalyst in deionized water to prepare a solution with a solubility of 0.1M, then adding the catalyst carrier (i.e., the mesoporous titanium dioxide or silicon dioxide nanospheres) to the above solution, stirring thoroughly for 12 hours, centrifuging (9000 rpm, 10 min) to collect the solid, washing it twice with deionized water, vacuum drying it at 60°C for 12 hours, and then calcining it in an air atmosphere at 400°C for 2 hours to obtain catalyst B.

[0051] Preferably, the temperature of the pyrolysis reaction in step (2) is 200-350°C, for example, it can be 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, 270°C, 280°C, 290°C, 300°C, 310°C, 320°C, 330°C, 340°C, 350°C, etc.; the pressure is 0.2-1MPa, for example, it can be 0.2MPa, 0.3MPa, 0.4MPa, 0.5MPa, 0.6MPa, 0.7MPa, 0.8MPa, 0.9MPa, 1MPa, etc.; the time is 1-10h, for example, it can be 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, etc.

[0052] In the present application, the preparation method, steps (1) and (2) are independently carried out in the presence of a protective atmosphere; the protective atmosphere includes but is not limited to nitrogen; in step (2), N2 is used to promote the discharge of by-product methanol during the reaction.

[0053] Preferably, step (2) further comprises a distillation step after the pyrolysis reaction.

[0054] Preferably, the temperature of the distillation is ≤ 150℃.

[0055] In the present application, after the pyrolysis reaction, the solvent is first removed by vacuum distillation, and then the by-products and products are separated by molecular distillation equipment; the temperature of the distillation kettle during the distillation process should not exceed 150℃, which can effectively reduce the polymerization reaction of isocyanate in the system.

[0056] In a third aspect, the present application provides a cycloaliphatic isocyanate trimer, which has the structure shown in formula III.

[0057]

[0058] In formula III, R 11 , R 12 , R 13 , R 21 , R 22 , R 23 are each independently selected from a single bond or a C1-C6 straight chain or branched alkylene group. The raw material for preparing the cycloaliphatic isocyanate trimer includes the cycloaliphatic diisocyanate of the first aspect.

[0059] In a fourth aspect, the present application provides a preparation method of the cycloaliphatic isocyanate trimer of the third aspect, which comprises the following steps:

[0060] Mixing the cycloaliphatic diisocyanate with a catalyst C to obtain the cycloaliphatic isocyanate trimer.

[0061] Preferably, the catalyst C includes at least one of 4-(β-hydroxypropyl)-1,4-diazabicyclo[2.2.2]octane-4-iso-octanoate, 4-(β-hydroxybutyl)-1,4-diazabicyclo[2.2.2]octane-4-iso-octanoate, 4-(β-hydroxyhexyl)-1,4-diazabicyclo[2.2.2]octane-4-hexanoate, 1-N,N,N-trimethyl-(3-hydroxypropylammonium) pivalate.

[0062] Preferably, the mass of the catalyst C is 0.02-3% of the mass of the alicyclic diisocyanate, for example, it can be 0.02%, 0.05%, 0.08%, 0.1%, 0.2%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 3%, etc.

[0063] Preferably, the preparation method comprises: mixing the alicyclic diisocyanate with the catalyst C in a formulation amount of 3-30% (for example, it can be 3%, 4%, 6%, 8%, 10%, 12%, 15%, 18%, 20%, 22%, 25%, 28%, 30%, etc.) at 0-100°C (for example, it can be 0°C, 10°C, 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, etc.; more preferably, 40-100°C, and particularly preferably, 60-90°C), and then increasing the system temperature by 5-25°C (for example, it can be 5°C, 6°C, 8°C, 10°C, 12°C, 14°C, 16°C, 18°C, 20°C, 22°C, 25°C, etc.), and then continuously adding the catalyst C in a formulation amount of 3-30% (for example, it can be 3%, 4%, 6%, 8%, 10%, 12%, 15%, 18%, 20%, 22%, 25%, 28%, 30%, etc.) to the system in batches after the system temperature starts to decrease, and then reacting for 1-5h (for example, it can be 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, etc.), until the monomer conversion rate is 15-40% (for example, it can be 15%, 16%, 18%, 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34%, 36%, 38%, 40%, etc.), and then continuously maintaining the reaction for 0.5-2h (for example, it can be 0.5h, 1h, 1.5h, 2h, etc.), to obtain the alicyclic isocyanate trimer mixture, and then performing post-treatment on the alicyclic isocyanate trimer mixture to obtain the alicyclic isocyanate trimer.

[0064] Preferably, the post-treatment comprises performing evaporation separation on the alicyclic isocyanate trimer mixture.

[0065] In the present application, the evaporation separation can be performed in a molecular rotary evaporator.

[0066] Preferably, the purity of the alicyclic isocyanate trimer is ≥99%.

[0067] In the trimerization reaction, the isocyanate is reacted in the presence of a catalyst, if necessary with a solvent or an auxiliary, until the desired conversion is achieved. Since the target conversion is usually far below 100%, this process is referred to as partial trimerization. After the reaction is completed, the reaction is terminated by deactivating the catalyst by adding an inhibitor. For example, dibutyl phosphate or toluenesulfonic acid is added, but this method results in the reaction product containing by-products such as isocyanurate groups. In the present application, in the preparation method of the alicyclic isocyanate trimer, by adding the catalyst in batches, the heat sustainability and controllability of the reaction are ensured, and the addition of the catalyst inhibitor is avoided, ensuring the efficient progress of the reaction and the stability of the quality of the final product.

[0068] In a fifth aspect, the present application provides a polyurethane coating, which comprises, by weight parts, 80-120 parts of a polymeric polyol (for example, it can be 80 parts, 85 parts, 90 parts, 95 parts, 100 parts, 105 parts, 110 parts, 115 parts, 120 parts, etc.), 40-60 parts of an alicyclic isocyanate trimer (for example, it can be 40 parts, 42 parts, 44 parts, 46 parts, 48 parts, 50 parts, 52 parts, 54 parts, 56 parts, 58 parts, 60 parts, etc.), 0.1-1 part of an auxiliary (for example, it can be 0.1 part, 0.2 part, 0.4 part, 0.6 part, 0.8 part, 1 part, etc.), and 20-60 parts of a solvent (for example, it can be 20 parts, 22 parts, 24 parts, 26 parts, 28 parts, 30 parts, 32 parts, 34 parts, 36 parts, 38 parts, 40 parts, 42 parts, 44 parts, 46 parts, 48 parts, 50 parts, 52 parts, 55 parts, 58 parts, 60 parts, etc.).

[0069] Preferably, the polymeric polyol comprises a polyester polyol and / or a polyether polyol.

[0070] Preferably, the polyester polyol comprises at least one of polycaprolactone polyol, polycarbonate polyol, and conventional polyester polyol.

[0071] In the present application, the conventional polyester polyol refers to a polyester polyol obtained by a polycondensation reaction of a dibasic carboxylic acid and a dihydric alcohol.

[0072] Preferably, the polyether polyol comprises at least one of polytetrahydrofuran polyol, polypropylene oxide polyol, and polyethylene oxide polyol.

[0073] Preferably, the auxiliary comprises a leveling agent.

[0074] Preferably, the leveling agent comprises a polyether-modified siloxane leveling agent.

[0075] Preferably, the solvent comprises butyl acetate and / or xylene.

[0076] In the present application, the solvent includes ethyl acetate and xylene, and the volume ratio of the ethyl acetate and xylene is (0.5-2):1, and more preferably 1:1.

[0077] In the present application, the preparation method of the polyurethane coating includes uniformly mixing the components.

[0078] The numerical range in the present application includes not only the point values listed above, but also any point values between the above numerical ranges that are not listed, and the specific point values included in the range are not listed due to the length and for the sake of simplicity.

[0079] Compared with the prior art, the present application has the following beneficial effects:

[0080] The alicyclic diisocyanate provided by the present application has the advantages of low viscosity, fast curing speed, high hardness of the prepared material, simple preparation process, wide raw material sources, low cost, and the like, and the alicyclic isocyanate trimer prepared from the alicyclic diisocyanate does not contain volatile isocyanate, and meets the green environmental protection requirements. DETAILED DESCRIPTION

[0081] The technical solutions of the present application are further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only used to help understand the present application, and should not be regarded as specific limitations on the present application.

[0082] Unless otherwise specified, the alicyclic diamine used in the examples and comparative examples of the present application is derived from the cyclic by-product produced in the production process of hexamethylene diamine or mixed diamine.

[0083] Example 1

[0084] The present example provides an alicyclic diisocyanate, which is The preparation method of the alicyclic diisocyanate includes the following steps:

[0085] (1) Under a nitrogen atmosphere, 120 g of 2-aminoethylcyclopentylamine, 900 g of dimethyl carbonate, and 3.5 g of manganese acetate (2.92% of the mass of 2-aminoethylcyclopentylamine) are added to a flask with a condenser, and reacted at 90°C for 6 h to obtain a yellow liquid; the yellow liquid is cooled and filtered, and unreacted dimethyl carbonate and methanol are removed by distillation under reduced pressure; then 6 times the volume of distilled water is added to the distilled liquid, and white crystals are precipitated after standing, washed and dried to obtain a carbamate.

[0086] (2) 6 g of the carbamate obtained in step (1) was mixed with 300 g of chlorobenzene to obtain a carbamate solution having a mass concentration of 2%, and the carbamate solution and 0.3 g of a cobalt trioxide / silica catalyst (5% of the total mass of the carbamate, a loading of 27 wt%) were placed in an autoclave, which was sealed, purged with nitrogen, and then pressurized to about 0.1 MPa. After the leakage test, the temperature was raised to 260°C, the pressure was maintained at 0.8 MPa, the nitrogen purge amount was 100 mL / min, and pyrolysis was performed for 1 h. After the reaction was completed, the product was separated and collected by rotary evaporation, and the solvent was removed by distillation under reduced pressure to obtain the alicyclic diisocyanate.

[0087] Example 2

[0088] The present embodiment provides an alicyclic diisocyanate, which is The method for preparing the alicyclic diisocyanate includes the following steps:

[0089] (1) 114 g of 2-aminomethylcyclopentylamine, 1080 g of dimethyl carbonate, and 3.5 g of zinc acetate (3.1% of the mass of 2-aminomethylcyclopentylamine) were added to a flask with a condenser under a nitrogen atmosphere, and reacted at 80°C for 5 h to obtain a yellow liquid. After the yellow liquid was cooled and filtered, unreacted dimethyl carbonate and methanol were removed by distillation under reduced pressure. Then, 10 times the volume of distilled water was added to the distilled liquid, and white crystals were precipitated after standing. After washing and drying, the carbamate was obtained.

[0090] (2) 5.5 g of the carbamate obtained in step (1) was mixed with 350 g of toluene to obtain a carbamate solution having a mass concentration of 1.57%, and the carbamate solution and 0.5 g of a cobalt trioxide / zinc oxide / silica catalyst (9.1% of the total mass of the carbamate, a loading of 20 wt%) were placed in an autoclave, which was sealed, purged with nitrogen, and then pressurized to about 0.1 MPa. After the leakage test, the temperature was raised to 290°C, the pressure was maintained at 0.7 MPa, the nitrogen purge amount was 200 mL / min, and pyrolysis was performed for 2 h. After the reaction was completed, the product was separated and collected by rotary evaporation, and the solvent was removed by distillation under reduced pressure to obtain the alicyclic diisocyanate.

[0091] Example 3

[0092] The present embodiment provides an alicyclic diisocyanate, which is The method for preparing the alicyclic diisocyanate includes the following steps:

[0093] (1) Under a nitrogen atmosphere, 130 g of 1,2-diaminoethylcyclopentane, 1300 g of dimethyl carbonate, and 7 g of cobalt acetate (5.38% by mass of 1,2-diaminoethylcyclopentane) were added to a flask with a condenser, and reacted at 85°C for 3 h to obtain a yellow liquid. The yellow liquid was cooled, filtered, and unreacted dimethyl carbonate and methanol were removed by distillation under reduced pressure. Then, 10 volumes of distilled water were added to the distilled liquid, and white crystals were precipitated. The crystals were washed and dried to obtain a carbamate.

[0094] (2) 15 g of the carbamate obtained in step (1) was mixed with 285 g of dichlorobenzene to obtain a carbamate solution having a mass concentration of 5.26%. Then, the carbamate solution and 0.6 g of a molybdenum oxide / titanium dioxide catalyst (4% by mass of the carbamate, 14 wt% loading) were placed in an autoclave, and pyrolyzed at 300°C under a nitrogen atmosphere, at a pressure of 0.6 MPa, and at a nitrogen purge rate of 200 mL / min for 2 h. After the reaction, the product was separated and collected by distillation under reduced pressure and further by a rotary thin film evaporator to obtain the alicyclic diisocyanate.

[0095] Example 4

[0096] The present embodiment provides an alicyclic diisocyanate, which is The method for producing the alicyclic diisocyanate includes the following steps:

[0097] (1) Under a nitrogen atmosphere, 130 g of 1,2-diaminoethylcyclopentane, 1300 g of dimethyl carbonate, and 7 g of cobalt acetate (5.38% by mass of 1,2-diaminoethylcyclopentane) were added to a flask with a condenser, and reacted at 85°C for 3 h to obtain a yellow liquid. The yellow liquid was cooled, filtered, and unreacted dimethyl carbonate and methanol were removed by distillation under reduced pressure. Then, 10 volumes of distilled water were added to the distilled liquid, and white crystals were precipitated. The crystals were washed and dried to obtain a carbamate.

[0098] (2) 15 g of the carbamate obtained in step (1) was mixed with 285 g of dichlorobenzene to obtain a carbamate solution having a mass concentration of 5.26%. Then, the carbamate solution and 0.6 g of a molybdenum oxide / titanium dioxide catalyst (4% by mass of the carbamate, 14 wt% loading) were placed in an autoclave, and pyrolyzed at 300°C under a nitrogen atmosphere, at a pressure of 0.6 MPa, and at a nitrogen purge rate of 200 mL / min for 2 h. After the reaction, the product was separated and collected by distillation under reduced pressure and further by a rotary thin film evaporator to obtain the alicyclic diisocyanate.

[0099] Example 5

[0100] This example provides a cycloaliphatic diisocyanate, which is The method for preparing the cycloaliphatic diisocyanate includes the following steps:

[0101] (1) Under a nitrogen atmosphere, 100 g of 2-aminomethylcyclopentylamine, 800 g of dimethyl carbonate, and 4 g of manganese acetate (4% of the mass of 2-aminomethylcyclopentylamine) were added to a flask with a condenser, and reacted at 95°C for 4 h to obtain a yellow liquid; the yellow liquid was cooled and filtered, and unreacted dimethyl carbonate and methanol were removed by distillation under reduced pressure; then 6 times the volume of distilled water was added to the distilled liquid, and white crystals were precipitated after standing, washed and dried to obtain a carbamate.

[0102] (2) 15 g of the carbamate obtained in step (1) was mixed with 400 g of dimethylbenzene to obtain a carbamate subsolution with a mass concentration of 3.75%; the carbamate subsolution and 0.6 g of cobalt trioxide / silica catalyst (4% of the mass of the carbamate, with a loading of 20 wt%) were placed in a high-pressure reaction kettle, and pyrolyzed under a nitrogen atmosphere at a temperature of 280°C, with a pressure of 0.55 MPa, and a nitrogen purge of 200 mL / min for 3 h. After the reaction was completed, the temperature was lowered and filtered, and the solvent was removed by distillation under reduced pressure, and then the product was further separated and collected by a rotary thin film evaporator to obtain the cycloaliphatic diisocyanate.

[0103] Example 6

[0104] This example provides a cycloaliphatic diisocyanate, which is The method for preparing the cycloaliphatic diisocyanate includes the following steps:

[0105] (1) Under a nitrogen atmosphere, 150 g of 1,2-diaminoethylcyclopentane, 900 g of dimethyl carbonate, and 7 g of cobalt acetate (4.7% of the mass of 1,2-diaminoethylcyclopentane) were added to a flask with a condenser, and reacted at 80°C for 5 h to obtain a yellow liquid; the yellow liquid was cooled and filtered, and unreacted dimethyl carbonate and methanol were removed by distillation under reduced pressure; then 10 times the volume of distilled water was added to the distilled liquid, and white crystals were precipitated after standing, washed and dried to obtain a carbamate.

[0106] (2) 20 g of the carbamate obtained in step (1) was mixed with 300 g of dichlorobenzene to obtain a carbamate solution with a mass concentration of 6.7%, and the carbamate solution and 0.4 g of a molybdenum oxide / titanium dioxide catalyst (2% of the mass of the carbamate, 18 wt% loading) were placed in an autoclave, pyrolysis was carried out under a nitrogen atmosphere at a temperature of 300°C, a pressure of 0.8 MPa, and a nitrogen purge of 200 mL / min for 1 h. After the reaction was completed, the temperature was lowered, and the product was separated by rotary evaporation.

[0107] Example 7

[0108] This example provides a cycloaliphatic diisocyanate, which is The preparation method of the cycloaliphatic diisocyanate differs from that of Example 1 only in that 2-aminoethylcyclopentylamine is replaced by equimolar 1,2-cyclopentanediamine, and the other preparation methods are the same as those of Example 1.

[0109] In this example, the products obtained in steps (1) and (2) in Examples 1-7 were characterized by gas chromatography (Japan Tsushima, GC-2010Pro), and the purity and yield are shown in Table 1.

[0110] Table 1

[0111]

[0112] Application Example 1-1

[0113] This application example provides a cycloaliphatic isocyanate trimer, and the preparation method thereof comprises:

[0114] Under a nitrogen atmosphere, 500 g of cycloaliphatic diisocyanate (Example 1) was added to a reaction kettle, and the temperature was raised to 60°C. 50 mg of 4-(β-hydroxypropyl)-1,4-diazabicyclo[2.2.2]octane-4-isoctanoate catalyst (20% of the total mass of the catalyst) was added, and the stirring was continued. The reaction was gradually heated to 85°C, and when the system temperature began to drop, a small amount of catalyst was added in batches. The amount of catalyst added each time was 20% of the total amount of catalyst, and the total mass of the catalyst was 0.05% of the mass of the cycloaliphatic diisocyanate. The conversion rate reached 30%, and the clear transparent monomer-containing trimer mixture was obtained after cooling and filtering. The trimer mixture prepared above was separated by a molecular rotary evaporator, and the specific process was as follows: feed speed 7 Hz, feed temperature 90°C, evaporator temperature 140°C, condenser temperature 10°C, vacuum degree 0.1 mbar, and discharge temperature 100°C. A cycloaliphatic isocyanate trimer with a purity of ≥99% was separated.

[0115] Application Example 1-2

[0116] This application example provides a cycloaliphatic isocyanate trimer, and a preparation method thereof comprises:

[0117] Under a nitrogen atmosphere, 900 g of cycloaliphatic diisocyanate (Example 2) was added to a reaction kettle, and the temperature was raised to 70°C. 100 mg of 4-(β-hydroxybutyl)-1,4-diazabicyclo[2.2.2]octane-4-isoctanoate catalyst (11.1% of the total mass of the catalyst) was added, and the stirring was continued. The reaction was gradually heated to 90°C. When the temperature of the system began to drop, a small amount of catalyst was continuously added in batches. The amount of catalyst added each time was about 11% of the total amount of catalyst, and the total mass of the catalyst was 0.1% of the cycloaliphatic diisocyanate. The conversion rate reached 33%. After cooling and discharging, the clear and transparent monomer-containing trimer mixture was obtained after filtration. The trimer mixture prepared above was separated using a molecular rotary evaporator. The specific process was as follows: the feeding speed was 7 Hz, the feeding temperature was 90°C, the evaporator temperature was 140°C, the condenser temperature was 10°C, the vacuum degree was 0.1 mbar, and the discharge temperature was 100°C. The purity of the cycloaliphatic isocyanate trimer separated was ≥99%.

[0118] Application Example 1-3

[0119] This application example provides a cycloaliphatic isocyanate trimer, and a preparation method thereof comprises:

[0120] Under a nitrogen atmosphere, 800 g of cycloaliphatic diisocyanate (Example 3) was added to a reaction kettle, and the temperature was raised to 70°C. 80 mg of 4-(β-hydroxypropyl)-1,4-diazabicyclo[2.2.2]octane-4-isoctanoate catalyst (5% of the total mass of the catalyst) was added, and the stirring was continued. The reaction was gradually heated to 87°C. When the temperature of the system began to drop, a small amount of catalyst was continuously added in batches. The amount of catalyst added each time was about 5% of the total amount of catalyst, and the total mass of the catalyst was 0.2% of the cycloaliphatic diisocyanate. The conversion rate reached 39%. After cooling and discharging, the clear and slightly yellow monomer-containing trimer mixture was obtained after filtration. The trimer mixture prepared above was separated using a molecular rotary evaporator. The specific process was as follows: the feeding speed was 7 Hz, the feeding temperature was 90°C, the evaporator temperature was 140°C, the condenser temperature was 10°C, the vacuum degree was 0.1 mbar, and the discharge temperature was 100°C. The purity of the cycloaliphatic isocyanate trimer separated was ≥99%.

[0121] Application Example 1-4

[0122] This application example provides a cycloaliphatic isocyanate trimer, and a preparation method thereof comprises:

[0123] Under nitrogen atmosphere, 500 g of alicyclic diisocyanate (Example 4) was added into a reaction kettle, which was heated to 60℃, 90 mg of 1-N,N,N-trimethyl-(3-hydroxypropylammonium) neopentanoate catalyst (3.6% of the total mass of the catalyst) was added, and the stirring was continued. The reaction was gradually heated to 87℃, and when the temperature of the system began to drop, a small amount of catalyst was added in batches, each time the amount of catalyst was 3.6% of the total amount of catalyst, and the total mass of the catalyst was 0.5% of the alicyclic diisocyanate. The conversion rate reached 27%, and the clear light yellow monomer-containing trimer mixture was obtained after cooling and filtering. The trimer mixture prepared above was separated by a molecular rotary evaporator at a feed rate of 7 Hz, a feed temperature of 90℃, an evaporator temperature of 140℃, a condenser temperature of 10℃, a vacuum degree of 0.1 mbar, and a discharge temperature of 100℃. The purity of the trimer component was ≥99%.

[0124] Application Example 1-5

[0125] The application example provides an alicyclic isocyanate trimer, and a preparation method thereof.

[0126] Under nitrogen atmosphere, 550 g of alicyclic diisocyanate (Example 7) was added into a reaction kettle, which was heated to 60℃, 110 mg of 4-(β-hydroxypropyl)-1,4-diazabicyclo[2.2.2]octane-4-isooctanoate catalyst (10% of the total mass of the catalyst) was added, and the stirring was continued. The reaction was gradually heated to 80℃, and when the temperature of the system began to drop, a small amount of catalyst was added in batches, each time the amount of catalyst was 10% of the total amount of catalyst, and the total mass of the catalyst was 0.2% of the alicyclic diisocyanate. The conversion rate reached 29%, and the clear light yellow monomer-containing trimer mixture was obtained after cooling and filtering. The trimer mixture prepared above was separated by a molecular rotary evaporator at a feed rate of 7 Hz, a feed temperature of 90℃, an evaporator temperature of 140℃, a condenser temperature of 10℃, a vacuum degree of 0.1 mbar, and a discharge temperature of 100℃. The purity of the alicyclic isocyanate trimer was ≥99%.

[0127] Application Example 2-1

[0128] The application example provides a polyurethane coating, which comprises, in parts by weight, 100 parts of polycaprolactone polyol (Japan Daicel Chemical Industry Co., Ltd., L205AL), 50 parts of the alicyclic isocyanate trimer provided in Application Example 1-1, 0.5 parts of polyether-modified siloxane leveling agent (Foshan City Kolin New Material, KMT-5510S), and 40 parts of butyl acetate / xylene (volume ratio 1:1) mixed solvent.

[0129] Application Example 2-2

[0130] The present application example provides a polyurethane coating, which is different from the application example 2-1 only in that the isocyanate trimer is the alicyclic isocyanate trimer provided in the application example 1-2, and other components, amounts and preparation methods are the same as those in the application example 2-1.

[0131] Application Example 2-3

[0132] The present application example provides a polyurethane coating, which is different from the application example 2-1 only in that the isocyanate trimer is the alicyclic isocyanate trimer provided in the application example 1-3, and other components, amounts and preparation methods are the same as those in the application example 2-1.

[0133] Application Example 2-4

[0134] The present application example provides a polyurethane coating, which is different from the application example 2-1 only in that the isocyanate trimer is the alicyclic isocyanate trimer provided in the application example 1-4, and other components, amounts and preparation methods are the same as those in the application example 2-1.

[0135] Application Example 2-5

[0136] The present application example provides a polyurethane coating, which is different from the application example 2-1 only in that the isocyanate trimer is the alicyclic isocyanate trimer provided in the application example 1-5, and other components, amounts and preparation methods are the same as those in the application example 2-1.

[0137] Application Example 2-6

[0138] The present application example provides a polyurethane coating, which includes, in parts by weight, polycaprolactone polyol 90 parts (Japan Daicel Chemical Industry Co., Ltd., L205AL), the alicyclic isocyanate trimer provided in the application example 1-1 60 parts, polyether modified siloxane leveling agent 1 part, and butyl acetate / xylene (volume ratio 1:1) mixed solvent 50 parts.

[0139] Application Example 2-7

[0140] The present application example provides a polyurethane coating, which includes, in parts by weight, polycaprolactone polyol 110 parts (Japan Daicel Chemical Industry Co., Ltd., L205AL), the alicyclic isocyanate trimer provided in the application example 1-1 40 parts, polyether modified siloxane leveling agent 0.2 parts (Foshan City, KMT-5510S, KMT-5510S), and butyl acetate / xylene (volume ratio 1:1) mixed solvent 60 parts.

[0141] Performance Test

[0142] (1) Film appearance: polyurethane paint was coated to the surface of the substrate (aluminum material) to obtain a paint film; whether the paint film surface had defects and whether it presented uniform gloss was detected by visual inspection;

[0143] (2) Tack-free time and dry time: determined according to GB / T 1728-2020;

[0144] (3) Pencil hardness: determined according to GB / T 6739-2022.

[0145] The specific test results are shown in Table 2.

[0146] Table 2

[0147] Coat appearance Surface dry time (min) Through dry time (min) Pencil hardness Example 2-1 Smooth and glossy 15 80 3H Example 2-2 Smooth and glossy 16 83 3H Example 2-3 Smooth and glossy 14 73 2H Example 2-4 Smooth and glossy 14 80 2H Example 2-5 Smooth and glossy 25 110 3H Example 2-6 Smooth and glossy 14 76 3H Example 2-7 Smooth and glossy 20 100 2H

[0148] As can be seen from Table 2, after the cycloaliphatic isocyanate trimer curing agent prepared by the application is compounded with polyol resin, the paint film formed is smooth and bright, can be rapidly cured at room temperature, and the hardness of the paint film is greatly improved. As can be seen from application examples 2-1 to 2-7, the cycloaliphatic isocyanate trimer prepared by the application not only can improve the curing ability of the paint film, but also can effectively improve the hardness of the paint film.

[0149] The above specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the application, and it should be understood that the above description is only for specific embodiments of the application and is not intended to limit the application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the application shall be included in the protection scope of the application.

Claims

1. An alicyclic diisocyanate, characterized in that The alicyclic diisocyanate has a structure shown in Formula I: In formula I, R1 and R2 are each independently selected from a single bond or a C1-C6 straight or branched alkylene group.

2. The alicyclic diisocyanate according to claim 1, characterized in that Said R1 and R2 are not simultaneously selected from single bonds; Preferably, R1 and R2 are each independently selected from C1 to C6 straight or branched alkylene groups, and the difference in the number of carbon atoms between R1 and R2 is ≥1; Preferably, R1 and R2 are each independently selected from a single bond or a C1-C4 straight chain or branched alkylene group.

3. The alicyclic diisocyanate according to claim 1 or 2, characterized in that The alicyclic diisocyanate is selected from any one of the following compounds; 4. A method for preparing an alicyclic diisocyanate according to any one of claims 1 to 3, characterized in that: The preparation method comprises the following steps: (1) reacting an alicyclic diamine with a carbonate to obtain a carbamate; (2) subjecting the carbamate obtained in step (1) to a thermal decomposition reaction to obtain the alicyclic diisocyanate; The alicyclic diamine has a structure shown in Formula II: In formula II, R1 and R2 are selected from the same range as in formula I.

5. The preparation method according to claim 4, characterized in that The molar ratio of the alicyclic diamine to the carbonate in step (1) is less than 1; Preferably, the raw materials for the reaction in step (1) further include catalyst A; Preferably, the mass of the catalyst A is 2 to 13% of the mass of the alicyclic diamine; Preferably, the catalyst A comprises a Lewis acid; Preferably, the Lewis acid comprises at least one of manganese acetate, cerium nitrate, magnesium nitrate, magnesium acetate, chromium acetate, cobalt nitrate, cobalt acetate, zinc nitrate, and zinc acetate; Preferably, the reaction temperature in step (1) is 30-90° C. and the reaction time is 2-20 h; Preferably, the reaction in step (1) further includes a post-treatment step; the post-treatment includes filtration, precipitation and drying performed in sequence.

6. The preparation method according to claim 4 or 5, characterized in that The pyrolysis reaction in step (2) is carried out in a solvent; Preferably, the content of the solvent is such that the mass concentration of the carbamate is 0.05 to 10%; Preferably, the solvent comprises at least one of xylene, m-xylene, o-xylene, chlorobenzene or o-dichlorobenzene; Preferably, the raw materials for the pyrolysis reaction in step (2) further include catalyst B; Preferably, the mass of the catalyst B is 1 to 10% of the mass of the carbamate; Preferably, the catalyst B comprises a supported heterogeneous catalyst; Preferably, the catalyst B comprises at least one of supported cobalt trioxide, supported cobalt tetraoxide, supported molybdenum oxide, supported cobalt oxide, supported manganese oxide or supported zinc oxide; Preferably, the support of the catalyst B comprises mesoporous titanium dioxide and / or silicon dioxide nanospheres; Preferably, the loading amount of the catalyst B is 10 to 30 wt%; Preferably, the temperature of the pyrolysis reaction in step (2) is 200-350° C., the pressure is 0.2-1 MPa, and the time is 1-10 h; Preferably, the pyrolysis reaction in step (2) further includes a distillation step; Preferably, the distillation temperature is ≤150°C.

7. An alicyclic isocyanate trimer, characterized in that The alicyclic isocyanate trimer has a structure shown in Formula III: In formula III, R 11 、R 12 、R 13 、R 21 、R 22 、R 23 Each is independently selected from a single bond or a C1-C6 straight or branched alkylene group; The raw materials for preparing the alicyclic isocyanate trimer include the alicyclic diisocyanate according to any one of claims 1 to 3.

8. A method for preparing an alicyclic isocyanate trimer according to claim 7, characterized in that: The preparation method comprises the following steps: Mixing an alicyclic diisocyanate with a catalyst C and reacting them to obtain the alicyclic isocyanate trimer; Preferably, the catalyst C comprises at least one of 4-(β-hydroxypropyl)-1,4-diazabisheterocyclo[2.2.2]octane-4-isooctanoate, 4-(β-hydroxybutyl)-1,4-diazabisheterocyclo[2.2.2]octane-4-isooctanoate, 4-(β-hydroxyhexyl)-1,4-diazabisheterocyclo[2.2.2]octane-4-hexanoate, and 1-N,N,N-trimethyl-(3-hydroxypropylammonium) pivalate; Preferably, the mass of the catalyst C is 0.02 to 3% of the mass of the alicyclic diisocyanate; Preferably, the preparation method comprises: mixing an alicyclic diisocyanate and a catalyst C in a formula amount of 3 to 30% at 0 to 100° C., raising the system temperature by 5 to 25° C., reacting until the system temperature begins to drop, then adding the catalyst C in a formula amount of 3 to 30% in portions, reacting for 1 to 5 hours until the monomer conversion rate reaches 15 to 40%, and continuing the reaction at this temperature for 0.5 to 2 hours to obtain the alicyclic isocyanate trimer mixture, and post-treating the alicyclic isocyanate trimer mixture to obtain the alicyclic isocyanate trimer; Preferably, the post-treatment comprises evaporating and separating the alicyclic isocyanate trimer mixture; Preferably, the purity of the alicyclic isocyanate trimer is ≥99%.

9. A polyurethane coating, characterized in that: The polyurethane coating comprises, in parts by weight, 80 to 120 parts of polymer polyol, 40 to 60 parts of alicyclic isocyanate trimer, 0.1 to 1 part of an auxiliary agent and 20 to 60 parts of a solvent; The alicyclic isocyanate trimer includes the alicyclic isocyanate trimer according to claim 7.

10. The polyurethane coating according to claim 9, characterized in that The polymer polyol includes polyester polyol and / or polyether polyol; Preferably, the polyester polyol includes at least one of polycaprolactone polyol, polycarbonate polyol, and conventional polyester polyol; Preferably, the polyether polyol includes at least one of polytetramethylene glycol polyol, polyoxypropylene glycol polyol and polyoxyethylene glycol polyol; Preferably, the auxiliary agent includes a leveling agent; Preferably, the leveling agent comprises a polyether-modified silicone leveling agent; Preferably, the solvent comprises butyl acetate and / or xylene.

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