Polyisocyanate composition, preparation method thereof and coating composition

Abstract

The invention discloses a polyisocyanate composition, a preparation method thereof and a coating composition. The polyisocyanate composition contains an isocyanurate tripolymer A formed by three diisocyanate monomers, an imino oxadiazinedione tripolymer B formed by three diisocyanate monomers and a uretdione tripolymer C formed by three diisocyanate monomers, the content of the isocyanurate tripolymer A, the content of the imino oxadiazinedione tripolymer B and the content of the uretdione tripolymer C are a, b and c respectively, and the content of the isocyanurate tripolymer A, the content of the imino oxadiazinedione tripolymer B and the content of the uretdione tripolymer C meet the condition that c / b is larger than or equal to 0.01 and smaller than or equal to b / a. The composition not only has lower viscosity, but also has better heat resistance, and can ensure the comprehensive properties such as better glossiness and excellent appearance of a coating film.

Description

Technical Field

[0001] The invention relates to the field of isocyanates, in particular to a polyisocyanate composition and a coating composition. Background Art

[0002] Aliphatic polyisocyanates containing isocyanurate structures are widely used in high-end fields such as automotive original paint, repair paint and varnish due to their excellent weather resistance, chemical resistance and heat resistance. In recent years, due to the continuous improvement of environmental protection requirements, in order to reduce the use of organic solvents in the application process of coating compositions, polyisocyanates used as curing agents have gradually developed in the direction of low viscosity.

[0003] Currently disclosed methods for preparing low-viscosity polyisocyanate compositions containing isocyanurate structures mainly include reducing the reaction conversion rate and introducing modified components, for example:

[0004] US4801663A describes a low-viscosity polyisocyanate composition, in which the proportion of isocyanurate monocyclic polymer is as high as 70-75%, but its reaction conversion rate can only reach 12-21%, and the total yield of the reaction is significantly reduced. This method requires the removal of a large amount of unreacted monomers from the final reaction product, which greatly increases the cost of the method.

[0005] The allophanate-containing structure obtained by monool modification in CN101291970A and US5124427A can reduce the viscosity of the polyisocyanate composition, but the allophanate structure obtained by monool modification has poor crosslinking and compatibility, and the appearance and glossiness of the resulting paint film are insufficient when applied to the coating composition.

[0006] US5354834A reduces the viscosity of the product by controlling the content of isocyanurate trimer to less than 60% and the content of uretdione dimer to more than 10% in the composition. Increasing the content of uretdione dimer is beneficial to reducing the viscosity of the composition, but uretdione has a linear structure and poor crosslinking and compatibility, which is unfavorable to the hardness and appearance of the paint film, and there is a situation where the monomer content increases during storage.

[0007] CN101165048A and CN1757639A disclose a method for preparing a polyisocyanate containing an imidooxadiazinedione structure polymer, wherein it is disclosed that the imidooxadiazinedione structure has the function of reducing the viscosity of the polyisocyanate and has better crosslinking properties than the uretdione structure whose crosslinked product is a linear structure.

[0008] According to the prior art, it is difficult to simultaneously ensure a low viscosity and good crosslinkability in a polyisocyanate composition modified by urethane. Modification with uretdione or iminooxadiazinedione can reduce the viscosity of isocyanurate-type polyisocyanate compositions. However, it is difficult to achieve the introduction of an iminooxadiazinedione structure or a uretdione structure while ensuring the thermal stability of the composition and the excellent properties of the prepared paint film. Therefore, it is necessary to develop an aliphatic polyisocyanate that can reduce the viscosity while maintaining good crosslinkability and thermal stability, thereby ensuring the excellent properties of the resulting paint film. Summary of the Invention

[0009] To solve the above technical problems, the present invention first proposes a polyisocyanate composition. When controlling that the polyisocyanate composition contains an isocyanurate trimer A formed by 3 molecules of a diisocyanate monomer, an iminooxadiazinedione trimer B formed by 3 molecules of a diisocyanate monomer, and a uretdione group trimer C formed by 3 molecules of a diisocyanate monomer, and the contents of the three are a, b, and c respectively, and 0.01 ≤ c / b ≤ b / a is satisfied, the composition not only has a low viscosity, but also has good crosslinkability and heat resistance, and can ensure comprehensive properties such as good gloss and excellent appearance of the coating film.

[0010] Based on the second aspect of the present invention, the present invention also provides an application of the polyisocyanate composition in a coating composition, and the paint film prepared from the coating composition has excellent comprehensive properties.

[0011] To achieve the above object, the technical solutions adopted by the present invention are as follows:

[0012] A polyisocyanate composition, which is derived from an aliphatic or cycloaliphatic diisocyanate monomer and contains an isocyanurate structure, the polyisocyanate composition contains an isocyanurate trimer A represented by the following formula I, an iminooxadiazinedione trimer B represented by formula II, and a uretdione group trimer C represented by formula III,

[0013]

[0014] wherein, R 1 、R 2 、R 3 are each independently selected from C2-C14 linear or cyclic alkylene groups (such as C3, C4, C5, C6, C7, C8, C9, C10 or C12 alkylene groups), preferably pentamethylene and hexamethylene.

[0015] In the polyisocyanate composition, the mass contents of compound A, compound B, and compound C are a, b, and c respectively, and 0.01 ≤ c / b ≤ b / a is satisfied.

[0016] In the present invention, when the content ratio c / b of the uretdione group trimer C to the iminooxadiazinedione group trimer B is lower than 0.01, the viscosity of the polyisocyanate composition cannot be effectively adjusted to meet the application requirements; when the content ratio c / b of the uretdione group trimer C to the iminooxadiazinedione group trimer B is higher than the content ratio b / a of the iminooxadiazinedione trimer B to the isocyanurate trimer A, the crosslinkability and thermal stability of the polyisocyanate composition tend to decrease.

[0017] In the present invention, when the contents a, b, and c of the isocyanurate trimer A, the iminooxadiazinedione group trimer B, and the uretdione group trimer C in the polyisocyanate composition satisfy 0.01 ≤ c / b ≤ b / a, it can not only play a role in reducing the viscosity of the composition but also meet good crosslinkability and thermal stability, so that it can be widely used in the preparation of coatings with good film properties.

[0018] Generally, diisocyanates generate trimolecular polymers, pentamolecular polymers, heptamolecular polymers, and higher molecular weight multimolecular polymers through polymerization under the action of a trimerization catalyst. In a preferred embodiment of the present invention, the content of the diisocyanate trimer (including the trimers A, B, and C) formed by the polymerization of three molecules of diisocyanate in the polyisocyanate composition is 40 - 80 wt%. When the content of the diisocyanate trimer is above 40 wt%, the viscosity of the polyisocyanate composition can be effectively reduced, thereby reducing the use of solvents when used as a coating; when the content of the diisocyanate trimer is below 80%, the composition can have good crosslinkability, thereby ensuring excellent application performance of the composition.

[0019] In a preferred embodiment of the present invention, the viscosity of the polyisocyanate composition measured at 25°C is 100 - 4000 mPa·s. When the viscosity is lower than 100 mPa·s, the crosslinkability of the polyisocyanate composition is poor; when the viscosity is higher than 4000 mPa·s, the amount of solvent used when the composition is used as a coating is large, which is not conducive to environmental protection.

[0020] The polyisocyanate composition described in the present invention contains isocyanurate groups, iminooxadiazinedione groups, and uretdione groups.

[0021] Furthermore, the isocyanurate group is a functional group of a polyisocyanate formed by 3 molecules of diisocyanate monomers, and its specific structure is shown in the following formula (Ⅳ):

[0022]

[0023] Furthermore, the iminooxadiazinedione group is a functional group of a polyisocyanate formed by 3 molecules of diisocyanate monomers, and its specific structure is shown in the following formula (Ⅴ):

[0024]

[0025] Furthermore, the uretdione group is a functional group of a polyisocyanate formed from two molecules of diisocyanate monomer, and its specific structure is shown in the following formula (Ⅵ):

[0026]

[0027] Among them, the dashed line represents the bonding key of the group.

[0028] In a preferred embodiment of the present invention, in the polyisocyanate composition, the molar ratio of the iminooxadiazinedione group to the isocyanurate group is (0.01 - 0.2):1. By setting this ratio above the above lower limit value, the resulting polyisocyanate composition has a lower viscosity; by setting the above ratio below the above upper limit value, the polyisocyanate composition has better crosslinkability.

[0029] In a preferred embodiment of the present invention, in the polyisocyanate composition, the molar ratio of the uretdione group to the isocyanurate group is (0.01 - 0.1):1. By setting this ratio above the above lower limit value, the resulting polyisocyanate composition has a lower viscosity; by setting the above ratio below the above upper limit value, the polyisocyanate composition has better crosslinkability and better thermal stability.

[0030] Hereinafter, an example of the manufacturing method of the polyisocyanate composition of the present invention will be described, which specifically includes the following steps:

[0031] S1: Add an isocyanuration catalyst to an aliphatic or cycloaliphatic diisocyanate monomer, react it to a certain extent, and stop the reaction by adding a terminator to obtain reaction solution X;

[0032] S2: Add an iminooxadiazinedionization catalyst to an aliphatic or cycloaliphatic diisocyanate monomer, react it to a certain extent, and stop the reaction by adding a terminator to obtain reaction solution Y;

[0033] S3: Blend reaction solutions X and Y, add a certain amount of aliphatic / cycloaliphatic diisocyanate monomer to obtain a mixed system, and react this mixed system at a high temperature for a certain time to obtain reaction solution Z;

[0034] S4: Remove the unreacted diisocyanate monomer from reaction solution Z to obtain the polyisocyanate composition.

[0035] In a preferred embodiment of the present invention, the diisocyanate monomer is selected from one or more of tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, lysine diisocyanate, preferably pentamethylene diisocyanate and / or hexamethylene diisocyanate.

[0036] Preferably, the isocyanurate esterification catalyst includes quaternary ammonium base catalysts and / or quaternary ammonium salt catalysts, preferably any one or more of choline hydroxide, trimethylhydroxyethylammonium hydroxide, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, benzyltrimethylammonium hydroxide, tetraethylammonium formate, tetraethylammonium acetate, tetrabutylammonium caprate, trimethylhydroxypropylammonium formate, trimethylhydroxypropylammonium acetate, trimethylhydroxypropylammonium caprate, trimethylhydroxyethylammonium formate, and more preferably benzyltrimethylammonium hydroxide and / or tetrabutylammonium caprate.

[0037] Preferably, the iminooxadiazinedione catalyst is one or more of tetraethylammonium fluoride, tetra-n-butylammonium fluoride, cetyltrimethylammonium fluoride, tetramethylammonium triazole salt, tetrabutylphosphonium triazole salt.

[0038] Preferably, the dosage of the isocyanurate esterification catalyst is 20 - 500 ppm relative to the total mass of the aliphatic or alicyclic diisocyanate monomer in step S1; the dosage of the iminooxadiazinedione catalyst is 20 - 200 ppm relative to the total mass of the aliphatic / alicyclic diisocyanate monomer in step S2.

[0039] Preferably, the reaction conversion rate in step S1 is 20 - 60%, and the reaction conversion rate in step S2 is 10 - 30%.

[0040] Preferably, in step S3, the mixing ratio of reaction liquid X and reaction liquid Y is (0.1 - 10):1; the mass of the additional aliphatic or alicyclic diisocyanate monomer is 5 - 20% of the total mass of the diisocyanate monomers in steps S1 and S2.

[0041] Preferably, the polymerization reaction temperature in step S1 or step S2 is 30 - 120 °C; the reaction temperature in step S3 is 100 - 180 °C, and the reaction time is 100 - 240 min.

[0042] Preferably, in step S1 or step S2, the catalyst is poisoned by adding a terminator. Feasible terminators are, for example, di-n-butyl phosphate, diisooctyl phosphate, phosphoric acid, p-toluenesulfonic acid, etc. The method of selecting a suitable terminator according to the catalyst type to terminate the reaction is known and is not a limitation of the present invention here.

[0043] Preferably, in step S4, the unreacted diisocyanate monomer is removed by any one or a combination of the following methods: thin film evaporation method, falling film evaporation method, short path evaporation method, vacuum rectification method; preferably, the unreacted monomer is removed by a two-stage thin film evaporation method, for example, thin film evaporation is carried out at 120-180°C.

[0044] Preferably, the content of the unreacted diisocyanate monomer in the polyisocyanate composition is controlled to be below 0.2 wt%.

[0045] The above preparation process is only to conveniently provide a preparation process of a polyisocyanate composition, but this process is generally not used as any limitation on the polyisocyanate composition. According to the inventive concept disclosed above in the present invention, those skilled in the art are capable of obtaining a polyisocyanate composition meeting the requirements through other schemes, for example:

[0046] By mixing a commercially available iminooxadiazinedione-based polyisocyanate composition, a diisocyanate monomer, and an isocyanurate-based polyisocyanate composition in a certain proportion, heating for a certain time, and then removing the excess diisocyanate monomer, a polyisocyanate composition meeting the requirements is obtained.

[0047] In a preferred embodiment of the present invention, the iminooxadiazinedione-based polyisocyanate composition is preferably selected from N3900 (the molar content of the iminooxadiazinedione structure is about 42%), and the isocyanurate-based polyisocyanate is preferably selected from N3300 (the molar content of the isocyanurate structure is about 98%).

[0048] Preferably, N3900, N3300, and HDI are blended at a ratio of (0.5-1.5):1:(0.05-0.2) at room temperature, then heated at 120-180°C for 100-200 min, and subsequently the unreacted diisocyanate monomer is removed by thin film evaporation, thus obtaining a polyisocyanate composition meeting the requirements.

[0049] Unless otherwise specified, "wt%" in the present invention all refers to mass percentage.

[0050] The present invention also provides a coating composition prepared from the polyisocyanate composition described above.

[0051] The coating composition includes, for example, the polyisocyanate composition described in the present invention and a polyol, and the amounts of the two are, for example, (1-1.5):1 in terms of the molar ratio of the isocyanate group to the hydroxyl group.

[0052] The polyol can be any known auxiliary curing component, including but not limited to acrylic polyols, polyester polyols, etc. The acrylic polyol is, for example, obtained by polymerizing one or more of 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, and 2-hydroxybutyl acrylate; the polyester polyol is, for example, prepared by a condensation reaction of one or more of succinic acid, adipic acid, sebacic acid, and maleic anhydride with one or more alcohols selected from ethylene glycol, propylene glycol, diethylene glycol, and neopentyl glycol.

[0053] The molecular weight of the polyol is preferably above 2000 and below 8000. When the molecular weight of the polyol is lower than 2000, the crosslinking degree is poor when it is applied to the coating composition. When the molecular weight of the polyol is higher than 8000, the film compatibility is poor when it is applied to the coating composition, further affecting the gloss and texture of the film. When the molecular weight of the polyol is above 2000 and below 8000, excellent crosslinking degree and compatibility of the coating composition can be ensured simultaneously.

[0054] The beneficial effects of the present invention are as follows: By defining the content relationship among the uretdione group trimer, iminooxadiazinedione group trimer, and isocyanurate group trimer in the polyisocyanate composition, the product can simultaneously have a lower viscosity, better crosslinking property, and thermal stability. After being used in the coating composition, the amount of solvent used can be significantly reduced, which is more environmentally friendly, and it also has better film properties, and obvious improvements have been obtained in multiple aspects such as gloss and appearance performance. etc. Obvious improvements have been obtained in multiple aspects. Detailed implementation manners

[0055] The present invention will be further described below through specific examples. The examples described in the present invention are only for the purpose of illustrating the present invention and do not limit the scope of the present invention.

[0056] <Main raw material information>

[0057] HDI: Hexamethylene diisocyanate, Covestro AG

[0058] PDI: Pentamethylene diisocyanate, Covestro AG

[0059] N3900: Hexamethylene diisocyanate homopolymer, Covestro AG

[0060] N3300: Hexamethylene diisocyanate homopolymer, Covestro AG

[0061] Acrylic polyol Ac-1, Guangdong Tongde New Materials Co., Ltd.

[0062] N,N,N-Trimethylbenzylammonium hydroxide, Aladdin Reagent

[0063] Tetrabutylammonium fluoride, Aladdin reagent

[0064] Isooctanol, Aladdin reagent

[0065] Diisooctyl phosphate, Aladdin reagent

[0066] <Determination of product viscosity>

[0067] The viscosity of the products in the examples and comparative examples was measured using a Brookfield RC / S rheometer, with a rotor model CC-40, a constant temperature water bath, and the temperature controlled at 25 ± 0.1 °C. The shear rate was 25 S-1 - 250 S-1.

[0068] <Reaction conversion rate and diisocyanate trimer>

[0069] The reaction conversion rate refers to the mass ratio of the reacted and converted diisocyanate based on the mass of the starting diisocyanate raw material. The conversion rate of the reaction was monitored by quantitatively analyzing the diisocyanate monomer through gel permeation chromatography.

[0070] The determination of the content of diisocyanate trimer was carried out by gel permeation chromatography. The peak corresponding to three times the molecular weight of the diisocyanate was defined as the trimer.

[0071] The gel permeation chromatography instrument was LC-20AD / RID-10A, and the chromatographic columns were MZ-Gel SDplus 10E3A 5μm (8.0 × 300mm), MZ-Gel SDplus 500A 5μm (8.0 × 300mm), and MZ-Gel SDplus 100A 5μm (8.0 × 300mm) connected in series, manufactured by Shimadzu; the mobile phase was tetrahydrofuran; the flow rate was 1.0 mL / min; the analysis time was 40 min, and the column temperature was 35 °C.

[0072] <Determination of free diisocyanate monomer content>

[0073] Based on the method of GB / T18583-2008, the content of residual monomers in the reaction system was determined using an Agilent GC-7890B gas chromatograph manufactured by Agilent.

[0074] <NCO content (NCO%)>

[0075] The test for NCO% content was carried out with reference to the standard GB / T 12009.4.

[0076] <Determination of the contents of compounds A, B, and C>

[0077] Determine the mass ratio among the isocyanurate-based trimer (A), iminooxadiazinedione-based trimer (B), and uretidione-based trimer (C) in the polyisocyanate composition according to the following method. Specifically, carbamate the terminal isocyanate groups of compounds A, B, and C in the polyisocyanate composition with methanol and analyze it using a liquid chromatography-mass spectrometer (LC / MS). Calculate the mass ratio (c / b, b / a) among compounds A, B, and C using the area normalization method (ignoring the difference in relative correction factors).

[0078] The following are the sample preparation method and measurement method:

[0079] (1) Sample preparation

[0080] Weigh 100 mg of the polyisocyanate composition and add methanol to prepare a solution with a concentration of 10 mg / mL. Then let it stand for 2 days to allow the existing isocyanate groups to fully react with methanol.

[0081] (2) Measurement method

[0082] UPLC-HRMS device: Ultimate 3000-Thermo Q Exactive Focus

[0083] Chromatographic column: Agilent Extend C18 RRHD 2.1×100 mm 1.8 um

[0084] Column temperature: 40 °C

[0085] Detection: 220 nm

[0086] Flow rate: 0.3 mL / minute

[0087] Scanning range: 100 - 21500 m / z

[0088] Mobile phase: A: pure water (0.05% formic acid), B: pure acetonitrile (0.05% formic acid)

[0089] <Determination of the molar ratio of iminooxadiazinedione group, uretidione group to isocyanurate group>

[0090] In the present invention, the molar ratio (d / m, e / m) of the iminooxadiazinedione group, uretidione group to the isocyanurate group in the polyisocyanate composition is determined by quantitative 13 13CNMR test. The specific test conditions are as follows:

[0091] 1313C-NMR equipment: AVANCE600 (Bruker); BBO probe (Bruker); sample concentration: 30 wt%; resonance frequency: 150 MHz; chemical shift reference: 77.0 ppm (CDCl3); pulse program: zgig30; spectral width: 240 ppm; spectral center: 100 ppm

[0092] Isocyanurate group: integral value near 148.5 ppm / 3; Iminooxadiazinedione group: integral value near 145.5 ppm / 1; Uretdione group: integral value near 157.5 ppm / 2.

[0093] <Thermal stability test>

[0094] The thermal stability of the polyisocyanate composition of the present invention was tested by the following method. After 50 g of the polyisocyanate composition was sealed with nitrogen in a 125 mL wide-mouth glass bottle and loaded, it was placed in an oven at 50 °C for 60 days, and the content of free diisocyanate monomer in the polyisocyanate composition before and after storage was tested.

[0095] <Coating film ethanol rubbing resistance test>

[0096] Hydroxypropyl resin (AC1100B, Tongde Resin) and the polyisocyanate composition were mixed to prepare a coating material, in which the raw materials were added according to the molar ratio of isocyanate group to hydroxyl group of 1.1:1, the solid content of the coating material was 40%, and the solvent was butyl acetate and xylene with a mass ratio of 1:1.

[0097] Ethanol rubbing resistance test: After the paint film was scrape-coated, it was baked at 70 °C for 30 min, left for 24 h, and then the ethanol rubbing resistance test was carried out using a solvent-resistant wiping instrument, and the number of rubbing resistances was recorded.

[0098] <Appearance and gloss of the coating film>

[0099] The acrylic polyol Ac-1 and the polyisocyanate composition were mixed in such a way that the molar ratio (NCO / OH) of the NCO group of the polyisocyanate composition to the OH group of the acrylic polyol was 1.0, and it was adjusted to a solid content of 55% by mass using "SOLVESSO #100" (trade name, an aromatic solvent manufactured by Exxon Corporation) to prepare a coating composition. Then, the coating composition was applied onto an ABS plate (acrylonitrile-butadiene-styrene resin; black, 150 mm × 75 mm) by spraying so that the dry film thickness was 50 μm. After baking it under the conditions of 60 °C for 30 minutes, it was left standing for 1 week under the conditions of 23 °C and 50% humidity, thereby forming a coating film on the ABS plate.

[0100] Appearance of the coating film (sharpness and surface smoothness): Measured along the long side direction of the ABS board using the digital oscilloscope "Wave Scan DOI" (manufactured by BYK Gardner). "Wave Scan DOI" is configured as follows: The point light source of the laser irradiates the laser light at an angle of 60° from the perpendicular line relative to the film surface, and the detector receives the reflected light on the opposite side of the perpendicular line at the same angle. This device moves the point light source of the laser on the film surface and scans it, thereby measuring the brightness and darkness of the reflected light point by point at a specified interval, and can detect the optical profile of the film surface. The detected optical profile is subjected to spectral analysis through a filter, and the surface structure can be analyzed. Among them, the values in the Wb region (wavelength 0.3 - 1.0 mm) and Wc region (wavelength 1.0 - 3.0 mm) of the coating film are used for evaluation. The measured value is the arithmetic mean of the three measured values. Both Wb and Wc are indicators for the appearance of the coating film. Wb is an indicator for the sharpness of the coating film, and Wc is an indicator for smoothness. The smaller the value, the better the judgment.

[0101] Gloss of the coating film: Measure the 60° gloss of the coating film using "UGV-6P" (manufactured by Suga Test Instruments Co., Ltd.).

[0102] Examples 1-11 and Comparative Examples 1-3

[0103] Refer to the following methods and the distinguishing parameters in Table 1 to prepare different polyisocyanate compositions respectively. The physical properties and application evaluation data of the products are shown in Table 1 and Table 2.

[0104] Step 1): Add 1000 g of diisocyanate monomer to a 2 L four-necked flask, heat it to 65 °C under nitrogen protection, add 1 g of an isooctanol solution of N,N,N-trimethylbenzylammonium hydroxide with a mass concentration of 5% under stirring conditions, and start timing. Control the reaction temperature at 65 - 70 °C. When the reaction reaches a certain conversion rate, add 0.08 g of diisooctyl phosphate to terminate the reaction, and obtain reaction solution X.

[0105] Step 2): Add 1000 g of diisocyanate monomer to a 2 L four-necked flask, heat it to 65 °C under nitrogen protection, add 1 g of a 10% tetrabutylammonium fluoride isooctanol solution under stirring conditions, and start timing. Control the reaction temperature at 60 - 65 °C during the reaction. When the reaction reaches a certain conversion rate, add 0.21 g of diisooctyl phosphate to terminate the reaction, and obtain reaction solution Y.

[0106] Step 3): Blend 500 g of reaction solution X, 500 g of reaction solution Y, and 100 g of diisocyanate monomer, and then react at 150 °C for a certain time under nitrogen protection, and then lower the reaction temperature to room temperature to obtain reaction solution Z.

[0107] Step 4): Using a thin-film evaporator, distill the above reaction liquid Z twice under the conditions of 150 °C and 30 Pa to obtain a polyisocyanate composition with a diisocyanate monomer content of less than 0.2%.

[0108] Example 12

[0109] After blending 100 g of HDI, 500 g of N3900 and 500 g of N3300, react at 150 °C for 120 min under nitrogen protection, then quickly cool to room temperature, and remove the excess HDI by thin-film evaporation to obtain the polyisocyanate composition.

[0110] The process parameters and product physical property data of the examples and comparative examples are shown in Table 1.

[0111] Table 1. Process parameters and product physical property data of examples / comparative examples

[0112]

[0113]

[0114]

[0115] The application test data of the polyisocyanate compositions of the examples / comparative examples are shown in Table 2.

[0116] Table 2. Application test data of the polyisocyanate compositions of the examples / comparative examples

[0117]

[0118] It can be seen from the above table data that when the contents a, b, c of the isocyanurate trimer A, iminooxadiazinedione trimer B, and uretedione trimer C in the polyisocyanate composition satisfy 0.01 ≤ c / b ≤ b / a, it can not only reduce the viscosity of the composition but also meet good crosslinkability and thermal stability, thereby having better film appearance, gloss and solvent rub resistance, and the comprehensive performance is significantly improved.

[0119] The present invention illustrates the detailed method of the present invention through the above examples, but the present invention is not limited to the above detailed method, that is, it does not mean that the present invention must rely on the above detailed method to be implemented. Those skilled in the art should understand that any improvement of the present invention, the equivalent substitution of each raw material of the product of the present invention, the addition of auxiliary components, the selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A polyisocyanate composition which is derived from an aliphatic or cycloaliphatic diisocyanate monomer and contains an isocyanurate structure, the polyisocyanate composition containing an isocyanurate trimer A represented by the following formula I, an iminooxadiazinedione trimer B represented by formula II, and a uretdione trimer C represented by formula III, wherein, R 1 、R 2 、R 3 Each independently selected from C2-C14 linear or cyclic alkylene groups, preferably pentamethylene and hexamethylene groups.

2. The polyisocyanate composition according to claim 1, characterized in that, in the polyisocyanate composition, the mass contents of compound A, compound B, and compound C are a, b, and c respectively, and they satisfy 0.01 ≤ c / b ≤ b / a.

3. The polyisocyanate composition according to claim 1 or 2, characterized in that, the sum of the isocyanurate trimer A, the iminooxadiazinedione trimer B, and the uretdione trimer C is 40 - 80 wt% of the polyisocyanate composition; and / or, the viscosity measured at 25 °C is 100 - 4000 mPa·s.

4. The polyisocyanate composition according to any one of claims 1 - 3, characterized in that, in the polyisocyanate composition, the molar ratio of iminooxadiazinedione group to isocyanurate group is (0.01 - 0.2):

1.

5. The polyisocyanate composition according to any one of claims 1 - 4, characterized in that, in the polyisocyanate composition, the molar ratio of uretdione group to isocyanurate group is (0.01 - 0.1):

1.

6. A coating composition comprising the polyisocyanate composition according to any one of claims 1 - 5.

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