A polyisocyanate composition

Abstract

The application discloses a multi-isocyanate composition, including isocyanurate (methyl-substituted IPDI trimer) of structure A and isocyanurate (IPDI trimer) of structure B, by limiting the molar ratio of the two isocyanurates, the solubility of non-polar solvents is enhanced, which is beneficial to the use of downstream customers.

Description

Technical Field

[0001] This invention belongs to the technical field of polyisocyanates, and specifically relates to a polyisocyanate composition. Background Technology

[0002] The technology of modifying isophorone diisocyanate (IPDI) monomers under the action of catalysts is well known in the field. For example, polymerization or alcohol modification reactions are carried out. After the expected conversion rate is achieved, unreacted IPDI monomers are removed by vacuum distillation or thin-film evaporation to obtain IPDI-based polyisocyanate composition products. For reference, see patents US2004176562A1, US6093817, CN107827832, etc.

[0003] Polyisocyanate compositions prepared by IPDI polymerization have obvious fast-drying properties and have been widely used in the polyurethane coatings industry. Moreover, since polyisocyanate compositions prepared by IPDI are mostly solid at room temperature, it is common practice for customers in the industry to use them dissolved in solvents.

[0004] In actual downstream applications, it was found that IPDI-based polyisocyanate compositions have poor solubility in non-polar solvents and their turbidity tends to increase, which in turn affects the use by downstream customers. Summary of the Invention

[0005] In the course of actual research, researchers found that the presence of a specific methyl-substituted structure A in a polyisocyanate composition increases the solubility of the composition in nonpolar solvents.

[0006] To enhance the solubility of non-polar solvents, the technical solution adopted in this invention is as follows:

[0007] A polyisocyanate composition comprising an isocyanurate of structure A and an isocyanurate of structure B:

[0008] Structure A is:

[0009]

[0010] R'1, R'2, and R'3 are selected from the following four structures, wherein at least one of R'1, R'2, and R'3 is selected from structure (I) or structure (II);

[0011]

[0012]

[0013] In the above structural formula, one, two, or three of the groups R1, R2, R3, R4, R5, R6, and R7 are CH3, and the rest are hydrogen.

[0014] Structure B is

[0015] Z1, Z2, and Z3 can be any one or both of the following two structures:

[0016]

[0017] Meanwhile, the molar ratio of isocyanurate of structure A to isocyanurate of structure B is 0.0005-0.03.

[0018] In the polyisocyanate composition of the present invention, the molar ratio of isocyanurate of structure A to isocyanurate of structure B is 0.005-0.02.

[0019] The molar ratio of isocyanurates of structure A to structure B, when above the lower limit, enhances solubility in nonpolar solvents, which is beneficial to the paint film; when below the upper limit, it inhibits the increase in solution viscosity, which is beneficial to downstream application.

[0020] In this invention, structure B is an isophorone diisocyanate trimer, and structure A is a methyl-substituted isophorone diisocyanate trimer.

[0021] The method for controlling the molar ratio of isocyanurates of structure A and structure B is not specifically limited, as long as the purpose can be achieved. For example, the molar ratio of the present invention can be obtained directly by isophorone diisocyanate polymerization or by adding structure A.

[0022] If the composition is prepared by isophorone diisocyanate polymerization, the content of structure A and structure B in the final composition can be controlled by controlling the content of methyl-substituted isophorone diisocyanate in the raw material isophorone diisocyanate.

[0023] The structure of the methyl-substituted isophorone diisocyanate (methyl-substituted IPDI) is as follows:

[0024]

[0025] Among them, R1, R2, R3, R4, R5, R6, and R7 have the same meaning as Equation I and Equation II.

[0026] The content of methyl-substituted isophorone diisocyanate can be adjusted during the preparation of isophorone diisocyanate to obtain isophorone diisocyanate monomer containing methyl-substituted isophorone diisocyanate, or it can be controlled by adding it before the preparation of trimer.

[0027] The preparation process of IPDI involves reacting isophorone with hydrogen cyanide to produce isophorone nitrile, which is then reacted with ammonia and hydrogen to generate isophorone diamine, followed by phosgenation to obtain IPDI. Studies have shown that methyl-substituted IPDI monomers may be generated during the preparation process. The content of methyl-substituted products in IPDI can be controlled by adjusting reaction and / or separation conditions, such as controlling the methylamine content in the ammonia feedstock, the chloride content in the hydrogenation catalyst, or the number of distillations and distillation conditions. Methyl-substituted isophorone diisocyanate trimers (structure A) can also be prepared separately, with the molar ratio adjusted by adding them.

[0028] For a detailed preparation method of IPDI containing methyl-substituted isophorone diisocyanate, please refer to patent CN115894857A.

[0029] In this invention, the polyisocyanate composition based on isophorone diisocyanate contains isocyanurate of structure B at a mass content of 50%-75%, preferably 50%-70%, more preferably 55%-65%, and even more preferably 59%-63%, which can be determined by gel chromatography.

[0030] In this invention, the polyisocyanate composition based on isophorone diisocyanate contains isocyanate groups (-NCO) with a mass content of 16-18%, preferably 16.5-17.5%. On the one hand, the NCO group content in the composition should not be too low, as this is not conducive to the structural cross-linking of the paint film; on the other hand, the NCO content should not be too high, as this usually reduces the hardness of the paint film.

[0031] In this invention, the polyisocyanate composition based on isophorone diisocyanate can be in solid or solution form after being dissolved in a solvent;

[0032] Since the polyisocyanate composition described in this invention is in a solid state at room temperature, generally referring to 25°C, in some specific embodiments, the polyisocyanate composition based on isophorone diisocyanate described in this invention can also be dissolved in a solvent to obtain a polyisocyanate composition solution, which is in the state of a solution after being dissolved in a solvent.

[0033] In the polyisocyanate composition solution of the present invention, the solvent is selected from any one or a combination of at least two of butyl acetate, ethyl acetate, solvent oil, toluene, xylene, propylene glycol methyl ether acetate, diheptanone, etc.

[0034] Preferably, the solvent accounts for 28-32% by mass, for example 29%, 30%, 31%, and more preferably 30%, based on the total mass of the polyisocyanate composition solution being 100%. If the solvent content in the composition solution is too high, it will reduce the economic benefits of downstream applications, while if the solvent content is too low, it will make the solution viscosity too high, which is also not lower than that used downstream.

[0035] Preferably, the polyisocyanate composition solution corresponding to the solution state after dissolving it in a solvent, based on the total mass of the polyisocyanate composition solution of 100%, has an NCO group mass content of 11.2-12.8%, for example 11.3%, 11.6%, 11.9%, 12.2%, 12.5%, 12.8%, preferably 12%.

[0036] In some specific embodiments, the isophorone diisocyanate-based polyisocyanate composition of the present invention contains isophorone diisocyanate monomer content of less than 0.5 wt%, for example 0.01 wt%, 0.05 wt%, 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, preferably less than 0.35 wt%, more preferably less than 0.1 wt%. The reduced content of IPDI monomer is beneficial to downstream construction safety.

[0037] The method of polymerization of isophorone diisocyanate is not limited, as long as the composition of the polyisocyanate composition meets the aforementioned requirements of this invention.

[0038] According to the methods disclosed in the prior art, for example, it can be prepared by the following method:

[0039] In the presence of a polymerization catalyst, isophorone diisocyanate undergoes a polymerization reaction. The polymerization reaction is terminated when the mass content of NCO groups in the system is 20-30%, for example, 24%, 25%, 26%, or 27%. Unreacted monomers are then removed to obtain the polyisocyanate composition based on isophorone diisocyanate.

[0040] The basic method for the polymerization of isocyanates is known in the prior art. In the specific polymerization process, isophorone diisocyanate can be added to a round-bottom flask equipped with a reflux condenser, stirrer, thermometer and nitrogen inlet. Then the system is heated to the predetermined reaction temperature range (e.g. 50-110°C, such as 70°C or 90°C) and then a catalyst solution is added dropwise. As is well known to those skilled in the art, the specific operating parameters and operating sequence of the polymerization reaction are common knowledge in the field and will not be described in detail here.

[0041] In some specific embodiments, the amount of catalyst used is 0.001 to 0.1% of the mass of isophorone diisocyanate, for example 0.005%, 0.01%, 0.02%, 0.04%, 0.06%, 0.08%, preferably 0.01 to 0.03%.

[0042] The polymerization catalyst used in this invention is selected from: (1) hydroxides of tetraalkylammonium (e.g., tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrabutylammonium hydroxide, benzyltrimethylammonium hydroxide, etc.), or organic acid salts of tetraalkylammonium (e.g., tetramethylammonium acetate, tetraethylammonium butyrate, etc.); (2) hydroxides of hydroxyalkylammonium (e.g., trimethylhydroxypropylammonium, trimethylhydroxyethylammonium, triethylhydroxypropylammonium, etc.) or their organic acid salts (e.g., acetic acid, butyric acid, isooctanoic acid, etc.); or (3) metal salts (e.g., tin, zinc, etc.) of alkylcarboxylic acids (e.g., acetic acid, decanoic acid, octanoic acid, etc.); preferably one or more of (1) or (2).

[0043] In some specific embodiments, the catalyst used in this invention is dissolved in an organic solvent to prepare a catalyst solution, and then added to the system to catalyze the polymerization reaction.

[0044] Specifically, the catalyst concentration in the catalyst solution is 1-40%, for example 5%, 10%, 15%, 20%, 25%, 30%, 35%, preferably 10-30%.

[0045] Specifically, the organic solvent is selected from alcohol solvents, preferably any one or a combination of at least two of monools and diols. In this invention, the monool may be selected from any one or a combination of at least two of 1-propanol, 2-propanol, n-butanol, isobutanol, sec-butanol, tert-butanol, n-octanol, isooctanol, heptanol, n-butanol, hexanol, heptanol, or isooctanol; the diol may be selected from any one or a combination of at least two of diethylene glycol, 1,3-butanediol, 1,6-hexanediol, 1,4-butanediol, 2-ethyl-1,6-hexanediol, etc.

[0046] In some specific embodiments, when the above polymerization reaction proceeds to an NCO value of 23-28% in the system, such as 24%, 25%, 26%, or 27%, a terminator can be used to terminate the reaction. Specifically, the molar ratio of the terminator to the polymerization catalyst is 1-1.1, such as 1.02, 1.04, 1.06, or 1.08, preferably 1.

[0047] The terminator is selected from any one or a combination of at least two of phosphate esters or benzenesulfonic acid terminators, such as dibutyl phosphate, diisooctyl phosphate, or p-toluenesulfonic acid.

[0048] In some other embodiments, the polymerization reaction described above can also be terminated by heating and holding for a period of time. In specific implementation, the system can be heated to 120-130°C (e.g., 122°C, 124°C, 126°C, 128°C) and held for 30-60 minutes (e.g., 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes).

[0049] In some specific embodiments, an optional technical solution is to control the mass content of methyl-substituted IPDI in the raw material IPDI monomer to be 0.01%-0.27%, obtain a reaction solution under the above reaction conditions, and then remove the unreacted isophorone diisocyanate monomer in the polymerization reaction system by thin-film evaporation. In some specific embodiments, a thin-film evaporator can be used to remove the unreacted isophorone diisocyanate monomer in the reaction system at 170-200°C and 10-200 PaA (e.g., 50 PaA, 100 PaA, 150 PaA) to obtain the polyisocyanate composition of the present invention.

[0050] Another alternative technical solution is to directly polymerize the enriched methyl-substituted IPDI according to the above method to obtain a polyisocyanate composition rich in structure A. The polyisocyanate composition of the present invention can also be obtained by blending the composition rich in structure A with the polyisocyanate composition rich in structure B.

[0051] The IPDI-based polyisocyanate composition of the present invention can be used in automotive refinish paints, automotive original equipment manufacturer (OEM) paints, rail transportation coatings, and other fields.

[0052] Compared with the prior art, the advantages of the technical solution of the present invention are: while ensuring the appropriate viscosity for downstream construction, it can increase the solvent type of non-polar solvent, thereby benefiting downstream customers. Detailed Implementation

[0053] To better understand the present invention, the following embodiments further illustrate the content of the present invention.

[0054] The main raw material sources used in the following examples are as follows; unless otherwise specified, all other raw materials are common commercially available:

[0055] The main raw material sources for each of the following embodiments are as follows; unless otherwise specified, all other raw materials are common commercially available materials:

[0056] Isophorone diisocyanate (IPDI): Wanhua Chemical;

[0057] n-Hexyl alcohol: Sigma-Aldrich, 98%;

[0058] Isooctyl alcohol: Sigma-Aldrich, 98%;

[0059] n-Butanol: Sigma-Aldrich, 99%;

[0060] 1,3-Butanediol: Sigma-Aldrich, 99%;

[0061] Trimethylhydroxypropyl isooctanoate ammonium: Sigma-Aldrich, 95%;

[0062] Benzyltrimethylammonium hydroxide: Sigma-Aldrich, 95%;

[0063] Tetrabutylammonium hydroxide: Sigma-Aldrich, 95%;

[0064] Tetrabutylammonium acetate: Sigma-Aldrich, 96%

[0065] Dibutyl phosphate, Sigma-Aldrich, 97%;

[0066] Diisooctyl phosphate, Sigma-Aldrich, 96%;

[0067] p-Toluenesulfonic acid, Sigma-Aldrich, 95%;

[0068] Butyl acetate: National Pharmaceutical Reagent, 99%

[0069] Solvent oil S100: Huafeng Spandex industrial product.

[0070] The main testing methods used in the various embodiments of this invention are as follows:

[0071] 1. Test method for monomer content in polyisocyanate compositions: GB / T 18446-2009 shall be adopted.

[0072] 2. Determination of NCO group content: The NCO group content based on the total mass of the sample is obtained by neutralizing the isocyanate groups in the sample with excess 2 mol / L di-n-butylamine, followed by back titration with 1 mol / L hydrochloric acid. The calculation formula is as follows:

[0073]

[0074] Where: V—volume of hydrochloric acid standard solution used in titration of the sample, ml;

[0075] V0—The volume of hydrochloric acid standard solution used in the blank titration, in ml;

[0076] c—The actual concentration of the hydrochloric acid standard solution, in mol / L;

[0077] 0.04202 — The mass of isocyanate ions, expressed in grams, equivalent to 1.00 ml of standard hydrochloric acid solution [c(HCl) = 1.000 mol / L];

[0078] m—total sample mass, g.

[0079] 3. Test method for the content of methyl-substituted IPDI in IPDI monomers

[0080] The content of phase-methylated isophorone diisocyanate in the isophorone diisocyanate composition described in this invention can be analyzed by gas chromatography: the sample is dissolved in a solvent (preferably dichloromethane) and then analyzed by gas chromatography, detected by a flame ionization detector (FID), and quantitatively calculated by area normalization.

[0081] The chromatographic conditions are as follows:

[0082] Carrier gas: High-purity nitrogen gas that has been purified and dried (purity ≥ 99.999%);

[0083] Combustion gas: hydrogen (purity ≥ 99.999%), flow rate 40 mL / min;

[0084] Combustion aid: purified and dry air, with a flow rate of 400 mL / min;

[0085] Make-up gas: nitrogen, flow rate 30 mL / min;

[0086] Column flow rate: 1.06 mL / min;

[0087] Flow split ratio: 30:1;

[0088] Column temperature (programmed temperature): 140℃ held for 0 min, then increased to 220℃ at 10℃ / min, held for 1 min, then increased to 260℃ at 5℃ / min, held for 0 min, then increased to 280℃ at 10℃ / min, held for 1 min.

[0089] Inlet temperature: 270℃;

[0090] Detector temperature: 290℃;

[0091] Injection volume: 0.2 μL.

[0092] 4. Molar ratio of structure A to structure B:

[0093] The following method was used to determine the ratio of the isocyanurate structure formed by the polymerization of methyl-substituted IPDI to the isocyanurate trimer formed by the polymerization of 3 IPDIs (referred to as compound α) in the polyisocyanate composition.

[0094] Specifically, the terminal isocyanate groups of the polyisocyanate composition of this patent are urethane-esterified with methanol, and analyzed using liquid chromatography-mass spectrometry (LC / MS). The sample preparation method and determination method are described below.

[0095] ① Sample preparation method

[0096] Weigh 100 mg of the polyisocyanate composition and add methanol to make a concentration of 10 mg / mL. Then, let it stand for 2 days to allow the existing isocyanate groups to react completely with the methanol, thus preparing a methanol solution.

[0097] ② Measurement method

[0098] The methanol solution obtained above was measured using the following apparatus.

[0099] ·LC

[0100] Device: Waters ACQUITY UPLC

[0101] Column: Phenomenex, Kinetex 2.6μXB-C18 100A (inner diameter 2.1mm, length 50mm) Column temperature: 40℃

[0102] Detection: 220nm

[0103] Flow rate: 0.3 mL / min; Mobile phase: gradient of solutions A and B: A = water (0.05% formic acid), B = acetonitrile (0.05% formic acid)

[0104] Injection volume: 1μL

[0105] MS

[0106] Device: Waters, Synapt G2

[0107] Ionization: ESI

[0108] Pattern: Positive

[0109] Scan range: m / z 250~2000

[0110] The methanol adduct (compound β) of the isocyanurate trimer formed by the polymerization of 3 IPDI molecules was detected by detecting ion (m / z) 762.

[0111] For isocyanurate structures polymerized from methyl-substituted IPDI, the different numbers of methyl substitutions lead to differences in the ion (m / z) positions.

[0112] The ion peak positions (m / z) of isocyanurate structures polymerized from IPDI with one, two, or three methyl groups are 776, 790, and 804, respectively, and are defined as compounds a, b, and c.

[0113] The ion peak positions (m / z) of isocyanurate structures polymerized from IPDI with 4, 5, or 6 methyl groups are 818, 832, and 846, and are defined as compounds d, e, and f;

[0114] For isocyanurate structures polymerized from IPDI with 7, 8, or 9 methyl groups, the ion peak positions (m / z) are 860, 874, and 888, respectively, defining compounds g, h, and i.

[0115] The ratio of the peak area of ​​compounds a to i to the peak area of ​​compound β is calculated as the molar ratio of structure A to structure B.

[0116] 5. Evaluation method for the solubility of nonpolar solvents

[0117] The polyisocyanate composition was mixed with solvent oil S100 at a mass ratio of 1:1 to obtain a diluted solution, which was then tested using a HACH 2100 turbidimeter.

[0118] A turbidity of no more than 0.3 indicates excellent solubility;

[0119] Turbidity greater than 0.3 but not higher than 0.6 indicates good solubility;

[0120] Turbidity greater than 0.6 but not exceeding 0.9 indicates acceptable solubility;

[0121] Turbidity greater than 0.9 indicates poor solubility.

[0122] 6. Evaluation method for viscosity of polar solvents

[0123] The polyisocyanate composition was mixed with butyl acetate at a mass ratio of 7:3 to obtain a solution product, and the viscosity was tested at 25°C using a Broolfield DV2T viscometer.

[0124] Viscosity at 25℃ not exceeding 600 cP, which is excellent for downstream construction.

[0125] Viscosity at 25℃, not exceeding 800 cP, for downstream construction: Good;

[0126] Viscosity at 25℃, not exceeding 1000 cP, for downstream construction: medium;

[0127] Viscosity at 25℃ is greater than 1000 cP, which is poor for downstream construction.

[0128] 7. Test method for solid content:

[0129] Weigh an accurate amount of the composition solution sample (approximately 0.5 g) and place it in an aluminum foil dish (weighing accurately). Place the dish in a 120°C oven and let it stand for 2 hours. Remove it, cool it, and weigh it.

[0130] Solid content = (weight after drying - weight of aluminum foil dish) / sample weight * 100%.

[0131] Example 1

[0132] Preparation of catalyst solution: Tetrabutylammonium hydroxide was dissolved in n-butanol to prepare a 20wt% solution.

[0133] 1000g of IPDI (0.01% by mass of methyl-substituted IPDI) was placed in a round-bottom flask equipped with a reflux condenser, stirrer, thermometer, and nitrogen inlet. The reaction system was heated to 70°C, and then the catalyst solution prepared above (0.015% by mass of IPDI) was added dropwise to the reaction system with stirring. The polymerization reaction was carried out at a temperature between 70 and 80°C. When the NCO content of the reaction solution was 28%, dibutyl phosphate was added in an equal molar amount to the catalyst to terminate the reaction.

[0134] Unreacted isophorone diisocyanate monomers in the polymerization reaction solution were removed by evaporation using a thin-film evaporator at a temperature of 185°C and an absolute pressure of 50 Pa. After 10 min, the content of the monomers was reduced to 0.34 wt%. The IPDI trimer (i.e., isocyanate of structure B) with a mass content of 68% was dissolved in butyl acetate to obtain a solution product with a solid content of 70 wt%, thus obtaining polyisocyanate composition solution 1.

[0135] Example 2

[0136] Preparation of catalyst solution: Trimethylhydroxypropyl isooctanoate ammonium was dissolved in isooctyl alcohol to prepare a 30wt% solution.

[0137] 1000g of IPDI (0.08% by mass of methyl-substituted IPDI) was placed in a round-bottom flask equipped with a reflux condenser, stirrer, thermometer, and nitrogen inlet. The reaction system was heated to 80°C, and then the catalyst solution prepared above (0.016% by mass of IPDI) was added dropwise to the reaction system with stirring. The polymerization reaction was carried out at a temperature between 80 and 90°C. When the NCO content of the reaction solution was 25%, diisooctyl phosphate was added in an equal molar amount to the catalyst to terminate the reaction.

[0138] Unreacted isophorone diisocyanate monomers in the polymerization reaction solution were removed by evaporation using a thin-film evaporator at a temperature of 185°C and an absolute pressure of 50 Pa. The solution was held for 15 min to obtain a content of 0.32 wt% and an IPDI trimer (i.e., isocyanate of structure B) content of 62%. The solution was then dissolved in butyl acetate to obtain a solution product with a solid content of 70 wt%, resulting in polyisocyanate composition solution 2.

[0139] Example 3

[0140] Preparation of catalyst solution: Benzyltrimethylammonium hydroxide was dissolved in n-hexanol to prepare a 1 wt% solution.

[0141] 1000g of IPDI (methyl-substituted IPDI content 0.18%) was placed in a round-bottom flask equipped with a reflux condenser, stirrer, thermometer and nitrogen inlet; the above reaction system was heated to 60°C, and then the catalyst solution prepared above (catalyst amount is 0.015% of IPDI mass) was added dropwise to the reaction system with stirring. The polymerization reaction was carried out at a reaction temperature between 60 and 70°C. When the NCO mass content of the reaction solution system was 25%, diisooctyl phosphate with a molar ratio of 1.1 to the catalyst was added to terminate the reaction.

[0142] Unreacted isophorone diisocyanate monomers in the polymerization reaction solution were removed by evaporation using a thin-film evaporator at a temperature of 200°C and an absolute pressure of 100 Pa. The solution was held for 10 min to obtain a content of 0.33 wt% and an IPDI trimer (i.e., isocyanate of structure B) content of 62%. The solution was then dissolved in butyl acetate to obtain a solution product with a solid content of 70 wt%, resulting in polyisocyanate composition solution 3.

[0143] Example 4

[0144] Preparation of catalyst solution: Tetrabutylammonium acetate was dissolved in 1,3-butanediol to prepare a 10wt% solution.

[0145] 1000g of IPDI (methyl-substituted IPDI, mass content 0.35%) was placed in a round-bottom flask equipped with a reflux condenser, stirrer, thermometer, and nitrogen inlet. The reaction system was heated to 70°C, and then the catalyst solution prepared above (catalyst amount is 0.0155% of IPDI mass) was added dropwise to the reaction system with stirring. The polymerization reaction was carried out at a temperature between 70 and 80°C. When the NCO mass content of the reaction solution system was 23%, p-toluenesulfonic acid with an equimolar amount of catalyst was added to terminate the reaction.

[0146] Unreacted isophorone diisocyanate monomers in the polymerization reaction solution were removed by evaporation using a thin-film evaporator at a temperature of 200°C and an absolute pressure of 100 Pa. The solution was held for 10 minutes to obtain a content of 0.3 wt% and an IPDI trimer (i.e., isocyanate of structure B) content of 58%. The solution was then dissolved in solvent oil S100 to obtain a solution product with a solid content of 70 wt%, resulting in polyisocyanate composition solution 4.

[0147] Example 5

[0148] Preparation of catalyst solution: Benzyltrimethylammonium hydroxide was dissolved in isooctanol to prepare a 5 wt% solution.

[0149] 1000g of IPDI (0.55% by mass of methyl-substituted IPDI) was placed in a round-bottom flask equipped with a reflux condenser, stirrer, thermometer, and nitrogen inlet. The reaction system was heated to 90°C, and then the catalyst solution prepared above (0.016% by mass of IPDI) was added dropwise to the reaction system with stirring. The polymerization reaction was carried out at a temperature between 100 and 110°C. When the NCO content of the reaction solution was 26%, the system was raised to 130°C (heating rate of 1°C / min). After the heating was completed, the system was held for 30 minutes to obtain the polymerization reaction solution.

[0150] Unreacted isophorone diisocyanate monomers in the polymerization reaction solution were evaporated and removed using a thin-film evaporator at a temperature of 190°C and an absolute pressure of 50 Pa. The solution was held for 10 min to obtain a content of 0.3 wt% and an IPDI trimer (i.e., isocyanate of structure B) content of 64%. The solution was then dissolved in butyl acetate to obtain a solution product with a solid content of 70 wt%, resulting in a polyisocyanate composition solution 5.

[0151] Comparative Example 1

[0152] Preparation of catalyst solution: Same as in Example 3

[0153] 1000g of IPDI (methyl-substituted IPDI mass content: 0.002%) was placed in a round-bottom flask equipped with a reflux condenser, stirrer, thermometer and nitrogen inlet; the above reaction system was heated to 70°C, and then the catalyst solution prepared above (catalyst amount is 0.015% of IPDI mass) was added dropwise to the reaction system with stirring. The polymerization reaction was carried out at a temperature between 100 and 110°C. When the NCO mass content of the reaction solution system was 26%, dibutyl phosphate with an equimolar amount of tetrabutylammonium difluoride was added to terminate the reaction, and the polymerization reaction solution was obtained.

[0154] Unreacted isophorone diisocyanate monomers in the polymerization reaction solution were removed by evaporation using a thin-film evaporator at a temperature of 200°C and an absolute pressure of 100 Pa, resulting in a content of 0.33 wt% and an IPDI trimer (i.e., isocyanate of structure B) content of 64%. The product was then dissolved in butyl acetate to obtain a solution product with a solid content of 70%, yielding polyisocyanate composition 3-1.

[0155] Comparative Example 2

[0156] Preparation of catalyst solution: Same as in Example 3

[0157] 1000g of IPDI (methyl-substituted IPDI, mass content 0.60%) was placed in a round-bottom flask equipped with a reflux condenser, stirrer, thermometer, and nitrogen inlet. The reaction system was heated to 70°C, and then the catalyst solution prepared above (catalyst amount was 0.015% of IPDI mass) was added dropwise to the reaction system with stirring. The polymerization reaction was carried out at a temperature between 70 and 80°C. When the NCO mass content of the reaction solution system was 25%, dibutyl phosphate with an equimolar amount of tetrabutylammonium difluoride was added to terminate the reaction, and the polymerization reaction solution was obtained.

[0158] Unreacted isophorone diisocyanate monomers in the polymerization reaction solution were removed by evaporation using a thin-film evaporator at a temperature of 200°C and an absolute pressure of 100 Pa, resulting in a content of 0.33 wt% and an IPDI trimer (i.e., isocyanate of structure B) content of 62%. The product was then dissolved in butyl acetate to obtain a solution product with a solid content of 70%, yielding a polyisocyanate composition 3-2.

[0159] The composition and properties of the polyisocyanate compositions prepared in the above examples and comparative examples were tested, and the results are shown in Table 1.

[0160] Table 1. Composition and storage stability test results of polyisocyanate compositions

[0161]

[0162] The above results indicate that by controlling the molar ratio of isocyanurate of structure A to structure B, the solubility in nonpolar solvents can be enhanced while avoiding an increase in viscosity during downstream application.

[0163] Although the invention has been described in detail above for illustrative purposes, such description is merely for illustrative purposes, and those skilled in the art can make changes to it without departing from the spirit and scope of the invention, which is defined by the claims.

Claims

1. A polyisocyanate composition comprising isocyanurate of structure A and isocyanurate of structure B: wherein structure A is: R’ 1, R’ 2, R’ 3 are selected from the following four structures, wherein at least one of R’ 1, R’ 2, R’ 3 is selected from structure (I) or structure (II): wherein R 1, R 2, R 3, R 4, R 5, R 6, R 7 in the above formulae are 1 or 2 or 3 groups of CH 3, and the rest are hydrogen; Z 1, Z 2, Z 3 can be any one or both of the following two structures: wherein the molar ratio of the isocyanurate of structure A to the isocyanurate of structure B is 0.0005-0.

03. 2.The polyisocyanate composition of claim 1, wherein the molar ratio of the isocyanurate of structure A to the isocyanurate of structure B is 0.005-0.

02. 3.The polyisocyanate composition of claim 1 or 2, wherein the mass content of the isocyanurate of structure B is 50%-75%. 4.The polyisocyanate composition of claim 1 or 2, wherein the mass content of the isocyanurate of structure B is 50%-70%. Structure B is 5.The polyisocyanate composition of claim 1 or 2, wherein the mass content of the isocyanurate of structure B is 55-65%. 6.The polyisocyanate composition of claim 1 or 2, wherein the mass content of the isocyanurate of structure B is 59%-63%.

2. The polyisocyanate composition according to claim 1, characterized in that 7.The polyisocyanate composition of claim 1 or 2, wherein the mass content of isocyanate groups is 16-18%.

3. The polyisocyanate composition according to claim 1 or 2, characterized in that 8.The polyisocyanate composition of claim 1 or 2, wherein the mass content of isocyanate groups is 16.5-17.5%.

4. The polyisocyanate composition according to claim 3, characterized in that 9.The polyisocyanate composition of claim 1 or 2, wherein the polyisocyanate composition is dissolved in a solvent to obtain a polyisocyanate composition solution, and the solvent is selected from any one or a combination of at least two of butyl acetate, ethyl acetate, solvent oil, toluene, xylene, propylene glycol methyl ether acetate, diheptanone.

5. The polyisocyanate composition according to claim 4, characterized in that 10.The polyisocyanate composition of claim 9, wherein the mass content of the solvent is 28-32% based on the total mass of the polyisocyanate composition solution.

6. The polyisocyanate composition according to claim 5, characterized in that 11.The polyisocyanate composition of claim 9 or 10, wherein the mass content of NCO groups in the polyisocyanate composition solution corresponding to the solution state of the polyisocyanate composition dissolved in the solvent is 11.2-12.8% based on the total mass of the polyisocyanate composition solution.

7. The polyisocyanate composition according to claim 1, characterized in that, 12.The polyisocyanate composition of claim 1 or 2, wherein the content of isophorone diisocyanate monomers is less than 0.5wt%.

8. The polyisocyanate composition according to claim 7, characterized in that 13.The polyisocyanate composition of claim 1 or 2, wherein the content of isophorone diisocyanate monomers is less than 0.35wt%.

9. The polyisocyanate composition according to claim 1, characterized in that, 14.The polyisocyanate composition of claim 1 or 2, wherein the content of isophorone diisocyanate monomers is less than 0.1wt%.

10. The polyisocyanate composition according to claim 9, characterized in that ​ 11. The polyisocyanate composition according to claim 1, characterized in that, ​ 12. The polyisocyanate composition according to claim 1, characterized in that, ​ 13. The polyisocyanate composition according to claim 12, characterized in that ​ 14. The polyisocyanate composition according to claim 13, characterized in that ​

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