Polyisocyanate composition and coating composition

Abstract

The invention discloses a polyisocyanate composition and a coating composition, and the polyisocyanate composition is derived from an aliphatic / alicyclic diisocyanate monomer and contains an isocyanurate structure. The mass fraction of a polyisocyanate having a number average molecular weight of 200-500 (inclusive) with respect to the polyisocyanate composition in a spectrum of the polyisocyanate composition obtained by gel permeation chromatography (GPC) is A, and the allophanate structure is contained in a spectrum of the polyisocyanate composition obtained by nuclear magnetic carbon spectroscopy (13C-NMR), and the content of the allophanate structure in the spectrum of the polyisocyanate composition obtained by nuclear magnetic carbon spectroscopy (13C-NMR) is less than 1%. The molar ratio of the allophanate structure to the isocyanurate structure is B, and the relation between A and B meets the condition that A / B is larger than or equal to 0.1 and smaller than or equal to 10. The composition not only has low viscosity, but also has good cross-linking property, and can ensure good application performance of a coating film.

Description

Technical Field

[0001] This invention relates to a polyisocyanate composition, and more particularly to a polyisocyanate composition and a coating composition. Background Technology

[0002] Aliphatic polyisocyanates containing isocyanurate structures possess excellent weather resistance, chemical resistance, and heat resistance, making them widely used in high-end applications such as automotive original equipment paints, repair paints, and clear coats. In recent years, due to increasingly stringent environmental protection requirements, and in order to reduce the use of organic solvents in coating compositions, polyisocyanates used as curing agents have gradually shifted towards lower viscosity.

[0003] Currently disclosed methods for preparing low-viscosity polyisocyanate compositions containing isocyanurate structures mainly include using special catalysts, reducing reaction conversion rates, and introducing modifying components, for example:

[0004] CN115246793B describes a catalyst using an alkaline earth metal salt-modified layered inorganic silicate material as a support and a quaternary ammonium salt or quaternary ammonium base as the active component. This catalyst can increase the content of low molecular weight polymers and reduce the viscosity of polyisocyanate compositions. However, the catalyst preparation process is relatively complex.

[0005] US4801663A describes a low-viscosity polyisocyanate composition obtained by reducing reaction conversion, wherein the proportion of isocyanurate monocyclic polymer is as high as 70-75%, but its reaction conversion rate can only reach 12-21%, resulting in a significant reduction in the overall reaction yield. 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.

[0006] US5354834A achieved a reduction in product viscosity by controlling the content of urea diketone dimer in the polyisocyanate composition to be higher than 10%. Increasing the content of urea diketone dimer is beneficial for reducing the viscosity of the composition, but urea diketone has a linear structure, poor crosslinking and compatibility, which is detrimental to the hardness and appearance of the paint film, and there is a possibility of increased monomer content during storage.

[0007] CN1757639A discloses a method for preparing low-viscosity polyisocyanates. This patent uses quaternary ammonium salts or phosphonium salts of polyfluoric acid as catalysts to prepare polyisocyanates containing iminooxadiazine dione groups, which can reduce the viscosity of the polyisocyanate composition. However, the iminooxadiazine dione structure has poor stability, and the introduction of fluorine makes this method less safe and environmentally friendly.

[0008] Existing technologies reveal that the viscosity of polyisocyanate compositions can be reduced by using catalysts with special structures, but the catalyst preparation process is complex. Polyisocyanate compositions obtained by reducing reaction conversion rates are costly. Alcohol-modified polyisocyanate compositions struggle to simultaneously maintain low viscosity and good crosslinking properties. Modification with urea diketone or iminooxadiazine diketone can reduce the viscosity of isocyanuric acid-based polyisocyanate compositions, but these compositions exhibit poor thermal stability. Therefore, there is a need to develop an aliphatic polyisocyanate that can reduce viscosity while maintaining good crosslinking properties, thereby ensuring the superior performance of the resulting coating film. Summary of the Invention

[0009] To address the above technical problems, this invention first proposes a polyisocyanate composition. Through continuous research, the inventors discovered that, in the chromatogram of the polyisocyanate composition obtained by gel permeation chromatography (GPC), a differential absorption peak exists in the region with a number average molecular weight of 200 or higher and 500 or lower, and the mass fraction of the polyisocyanate with a number average molecular weight of 200 or higher and 500 or lower relative to the polyisocyanate composition is A; by nuclear magnetic resonance (NMR) carbon spectroscopy... 13 The polyisocyanate composition obtained by C-NMR contains a urethane structure, and the molar ratio of the urethane structure to the isocyanurate structure is B; when the relationship between A and B satisfies 0.1≤A / B≤10, the composition not only has low viscosity, but also good crosslinking properties.

[0010] Based on a second aspect of the invention, the invention also provides the application of the polyisocyanate composition in a coating composition, wherein the coating film obtained by the coating composition has excellent overall performance.

[0011] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0012] A polyisocyanate composition derived from aliphatic and / or alicyclic diisocyanate monomers and containing an isocyanurate structure, wherein:

[0013] In the spectrum of the polyisocyanate composition obtained by gel permeation chromatography (GPC), a differential absorption peak exists in the region with a number average molecular weight of 200 or higher and 500 or lower, and the mass fraction of the polyisocyanate with a number average molecular weight of 200 or higher and 500 or lower relative to the polyisocyanate composition is A. This is further confirmed by carbon NMR spectroscopy. 13 The spectrum of the polyisocyanate composition obtained by C-NMR contains a urethane structure, and the molar ratio of the urethane structure to the isocyanurate structure is B, wherein the relationship between A and B satisfies 0.1≤A / B≤10.

[0014] Studies have found that in the polyisocyanate composition, when A / B < 0.1, the polyisocyanate composition has poor crosslinking properties; when A / B > 10, the polyisocyanate composition has high viscosity; when 0.1 ≤ A / B ≤ 10, the polyisocyanate composition has both low viscosity and good crosslinking properties, thus it can be widely used in the preparation of coatings with excellent film performance.

[0015] In the polyisocyanate composition of the present invention, the mass fraction of the polyisocyanate with a number average molecular weight of 200 or more and 500 or less relative to the polyisocyanate composition is A. When the value of A is 0.5% to 5%, the composition can further ensure lower viscosity and better crosslinking.

[0016] In a preferred embodiment of the present invention, the aliphatic and / or alicyclic diisocyanate monomer is selected from one or more of tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), dicyclohexylmethane diisocyanate (HMDI), cyclohexane dimethylene diisocyanate (HXDI), and lysine diisocyanate, preferably pentamethylene diisocyanate and / or hexamethylene diisocyanate.

[0017] The polyisocyanate composition of the present invention comprises isocyanurate group, urea carbamate group, iminooxadiazine dione group and urea dione group.

[0018] Furthermore, the isocyanurate group is a functional group of a polyisocyanate formed by three diisocyanate monomers, and its specific structure is shown in formula (Ⅰ):

[0019]

[0020] Furthermore, the urea-formate group is a functional group of a polyisocyanate formed by two molecules of diisocyanate monomer and one molecule of alcohol, and its specific structure is shown in formula (II):

[0021]

[0022] Furthermore, the iminooxadiazine dione group is a functional group of a polyisocyanate formed from 3 molecules of diisocyanate monomers, and its specific structure is shown in formula (Ⅲ):

[0023]

[0024] Furthermore, the urea diketone group is a functional group of a polyisocyanate formed by two diisocyanate monomers, and its specific structure is shown in formula (Ⅳ):

[0025]

[0026] In a preferred embodiment of the present invention, the molar ratio of iminooxadiazine dione groups to isocyanurate groups in the polyisocyanate composition is (0.01-0.05):1. By setting this ratio above the lower limit, the resulting polyisocyanate composition has a lower viscosity; by setting the ratio below the upper limit, the polyisocyanate composition has better crosslinking properties.

[0027] In a preferred embodiment of the present invention, the molar ratio of urea diketone groups to isocyanurate groups in the polyisocyanate composition is (0.005-0.02):1. By setting this ratio above the lower limit, the resulting polyisocyanate composition has a lower viscosity; by setting the ratio below the upper limit, the polyisocyanate composition has better crosslinking properties and better thermal stability.

[0028] In a preferred embodiment of the present invention, the viscosity of the polyisocyanate composition, measured at 25°C, is 100-4000 mPa·s, preferably 500-3000 mPa·s. When the viscosity is below 100 mPa·s, the polyisocyanate composition exhibits poor crosslinking properties; when the viscosity is above 4000 mPa·s, the composition requires a large amount of solvent when used as a coating, which is detrimental to environmental protection.

[0029] The following describes an example of a method for manufacturing the polyisocyanate composition of the present invention, specifically including the following steps:

[0030] S1: Add a trimerizing catalyst to an aliphatic / alicyclic diisocyanate monomer to allow it to react to a certain extent, and then stop the reaction by adding a terminator to obtain reaction solution X;

[0031] S2: A certain amount of alcohol is mixed into an aliphatic / alicyclic diisocyanate monomer, followed by the addition of a urea-formylation catalyst to allow the reaction to proceed to a certain extent. The reaction is then stopped by adding a terminator to obtain reaction solution Y.

[0032] S3: Mix reaction solution X and reaction solution Y in a certain proportion to obtain reaction solution Z;

[0033] S4: Remove unreacted diisocyanate monomers from reaction solution Z to obtain the polyisocyanate composition.

[0034] In a preferred embodiment of the present invention, the trimerizing catalyst in step S1 comprises a quaternary ammonium base and / or a quaternary ammonium salt catalyst, preferably any one or at least two combinations of choline hydroxide, trimethylhydroxyethylammonium hydroxide, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, benzyltrimethylammonium hydroxide, tetraethylammonium formate, tetraethylammonium acetate, tetrabutylammonium decanoate, trimethylhydroxypropylammonium formate, trimethylhydroxypropylammonium acetate, trimethylhydroxypropylammonium decanoate, and trimethylhydroxyethylammonium formate, and more preferably benzyltrimethylammonium hydroxide and tetrabutylammonium decanoate.

[0035] Preferably, the temperature of the trimerization reaction in step S1 is 30-100℃.

[0036] Preferably, the amount of the trimerizing catalyst is 20-500 ppm relative to the total mass of the aliphatic / alicyclic diisocyanate monomers in step S1.

[0037] Preferably, the reaction conversion rate in step S1 reaches 20-50%, and the catalyst is poisoned by adding a terminator. Feasible terminators include di-n-butyl phosphate, diisooctyl phosphate, phosphoric acid, p-toluenesulfonic acid, phosphoric acid, etc. The method of selecting a suitable terminator to terminate the reaction according to the catalyst selection is known and is not intended to limit the present invention in any way.

[0038] Preferably, the urea-formylation catalyst in step S2 can be: alkyl carboxylates of tin, lead, zinc, bismuth, zirconium, zirconium oxycarboxyl, etc.; organotin compounds such as tin 2-ethylhexanoate and dibutyltin dilaurate; organolead compounds such as lead 2-ethylhexanoate; organozinc compounds such as zinc 2-ethylhexanoate; bismuth 2-ethylhexanoate, zirconium 2-ethylhexanoate, zirconium oxy2-ethylhexanoate. One type can be used alone, or two or more can be used in combination.

[0039] Preferably, the amount of the urea-formylation catalyst used in step S2 is 20-1000 ppm relative to the total mass of the aliphatic / alicyclic diisocyanate monomers.

[0040] Preferably, the alcohol in step S2 can be a monool, a polyol, or a mixture of these alcohols. Specifically, examples of monools include ethanol, 1-propanol, 2-propanol, 1-butanol, 2-methyl-1-propanol, 2-butanol, 1-pentanol, 3-methyl-1-butanol, 2-methyl-1-butanol, 2,2-dimethyl-1-propanol, 2-pentanol, 3-methyl-2-butanol, 3-pentanol, 2-methyl-2-butanol, 1-hexanol, 2-hexanol, 3-hexanol, 3-methyl-2-pentanol, 4-methyl-2-pentanol, 2-methyl-3-pentanol, 1-heptanol, 2-heptanol, 3-heptanol, 4-heptanol, 1-octanol, 6-methyl-1-heptanol, isooctanol, etc. Specifically, examples of polyols include ethylene glycol, 1,3-butanediol, neopentyl glycol, 2-ethylhexanediol, etc.

[0041] Preferably, the amount of alcohol used in step S2 is 1-20% relative to the total mass of the aliphatic / alicyclic diisocyanate monomer.

[0042] Preferably, the urea-formaldehyde esterification reaction temperature in step S2 is 80-150°C.

[0043] Preferably, when the isocyanate conversion rate reaches 5-30% in step S2, the catalyst is poisoned by adding a terminator. Feasible terminators include di-n-butyl phosphate, diisooctyl phosphate, phosphoric acid, p-toluenesulfonic acid, phosphoric acid, etc. The method of selecting a suitable terminator to terminate the reaction according to the catalyst selection is known and is not intended to limit the present invention in any way.

[0044] Preferably, the mixing ratio of reaction solution X and reaction solution Y in step S3 is 1:(0.1-0.5).

[0045] Preferably, in step S4, unreacted diisocyanate monomers are removed by any one or more of the following methods in combination: thin-film evaporation, falling film evaporation, short-path evaporation, and vacuum distillation; preferably, unreacted monomers are removed by a two-stage thin-film evaporation method, for example, thin-film evaporation is carried out at 120-180°C.

[0046] Preferably, the content of unreacted diisocyanate monomers in the polyisocyanate composition is controlled to be below 0.2 wt%.

[0047] The above preparation process is merely provided for convenience in preparing a polyisocyanate composition, and is not generally intended to limit the polyisocyanate composition. Based on the inventive concept disclosed above, those skilled in the art can obtain satisfactory polyisocyanate compositions through other methods, such as:

[0048] A commercially available isocyanurate-based polyisocyanate composition, diisocyanate monomer, urea-formate-based polyisocyanate composition, and a certain amount of acidic substance are mixed in a certain proportion and heated for a certain time. Then, excess diisocyanate monomer is removed to obtain a polyisocyanate composition that meets the requirements.

[0049] As a feasible implementation plan, further examples are as follows:

[0050] 200g of commercially available HDI, 500g of commercially available HT-100 (with an isocyanurate molar content of approximately 90%), and 100g of commercially available HT-300 (with an isocyanurate molar content of approximately 50%) were mixed together, and a certain amount of acidic substance was added. The mixture was then reacted at 150°C for 90 minutes under nitrogen protection, and then rapidly cooled to room temperature. Excess HDI was removed by thin-film evaporation to obtain the target product.

[0051] Unless otherwise specified, "wt%" in this invention refers to mass percentage.

[0052] The present invention also provides a coating composition prepared from the polyisocyanate composition described above.

[0053] The coating composition may include, for example, the polyisocyanate composition and polyol provided above, in amounts based on the molar ratio of isocyanate groups to hydroxyl groups, for example, (1-1.5):1.

[0054] The polyol can be any known auxiliary curing component, including but not limited to acrylic polyols and polyester polyols. For example, the acrylic polyol is obtained by polymerizing one or more of 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, and 2-hydroxybutyl acrylate; the polyester polyol is prepared, for example, by 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.

[0055] The beneficial effects of this invention are as follows:

[0056] By defining the mass fraction (A) of polyisocyanates with a number average molecular weight of 200 or higher and 500 or lower relative to the total mass of the polyisocyanate composition, and the molar ratio (B) of urea-formate structures relative to isocyanurate structures, with A and B satisfying the relationship 0.1 ≤ A / B ≤ 10, the composition not only exhibits low viscosity but also good crosslinking properties, thereby ensuring excellent performance of the resulting paint film. Significant improvements are achieved in drying speed, film hardness, solvent resistance, and other aspects. Detailed Implementation

[0057] The present invention will be further illustrated below with specific embodiments. These embodiments are merely illustrative and do not limit the scope of the invention.

[0058] <Main Raw Material Information>

[0059] HDI: Hexamethylene diisocyanate, Wanhua Chemical Co., Ltd.

[0060] PDI: Pentamethylene diisocyanate, Wanhua Chemical Co., Ltd.

[0061] N,N,N-Trimethylbenzylammonium hydroxide, Aladdin Reagent Platform

[0062] Isooctyl alcohol, Aladdin Reagent Platform

[0063] di-n-butyl phosphate, Aladdin Reagent Platform

[0064] <Determination of Product Viscosity>

[0065] The viscosity of the products in the examples and comparative examples was measured using a Brookfield RC / S rheometer with a CC-40 rotor, in a constant temperature water bath at 25 ± 0.1 °C. The shear rate was 25 s⁻¹ to 250 s⁻¹.

[0066] <Reaction Conversion Rate>

[0067] The reaction conversion rate refers to the mass ratio of diisocyanate that has been reacted and converted, based on the mass of the initial diisocyanate feedstock. The conversion rate is monitored by quantitative analysis of diisocyanate monomers using size exclusion liquid chromatography.

[0068] The size exclusion liquid chromatography instrument was an Agilent 1260, and the chromatographic columns were Pl1113-6520 and Pl113-6325 (Agilent); the mobile phase was tetrahydrofuran; the flow rate was 1.0 mL / min; the detection method was a differential detector; the sample concentration was 3 wt%; the analysis time was 40 min; and the column temperature was 35 °C.

[0069] <The mass fraction of the polyisocyanate with a number average molecular weight of 200 or more and 500 relative to the polyisocyanate composition is A>

[0070] The polyisocyanate composition was determined using GPC. The mass fraction of polyisocyanates with a number-average molecular weight of 200 or higher and 500 or lower relative to the polyisocyanate composition was determined using the area normalization method.

[0071] The liquid phase size exclusion chromatography polymer testing conditions used are as follows:

[0072] GPC equipment: Agilent 1260

[0073] GPC pillars: PL1113-6520 and PL113-6325 (Agilent)

[0074] Sample concentration: 3wt%

[0075] Mobile phase: Tetrahydrofuran

[0076] Detection method: Differential detector

[0077] Flow rate: 1 ml / min

[0078] Column temperature: 35℃

[0079] <Determination of Free Diisocyanate Monomer Content>

[0080] This invention is based on the method of GB / T18583-2008, and uses an Agilent GC-7890B gas chromatograph manufactured by Agilent to determine the content of residual monomers in the reaction system.

[0081] <NCO content (NCO%)>

[0082] The NCO% content test shall be performed in accordance with standard GB / T 12009.4.

[0083] <Determination of the molar ratio of urea-formate group, iminooxadiazine dione group, urea-dione group and isocyanurate group>

[0084] In this invention, the molar ratio of iminooxadiazine dione groups, ureidone groups, and isocyanurate groups in the polyisocyanate composition is quantified by the composition. 13 The result is obtained through CNMR testing. The specific test conditions are as follows:

[0085] 13 C-NMR equipment: AVANCE 600 (Bruker); BBO probe (Bruker); Sample concentration: 30 wt%; Resonance frequency: 150 MHz; Shift reference: 77.0 ppm (CDCl3); Pulse program: zgig30; Spectral width: 240 ppm; Spectral center: 100 ppm

[0086] Isocyanurate group: integral value around 148.5 ppm / 3; Urea carbamate group: integral value around 154 ppm / 1; Iminooxadiazine dione group: integral value around 145.5 ppm / 1; Urea dione group: integral value around 157.5 ppm / 2.

[0087] <Coating Application Performance Test>

[0088] A coating is prepared by mixing hydroxypropyl resin (AC1100B, Tongde resin) and a polyisocyanate composition, wherein the raw materials are added according to the molar ratio of isocyanate groups to hydroxyl groups of 1.1:1, the coating has a solid content of 40%, and the solvent is butyl acetate and xylene in a mass ratio of 1:1.

[0089] Drying time test: Use a linear drying time recorder to read the drying time according to the national standard GB / T 1728.

[0090] Pendulum hardness test: After spraying / scraping the sample, place it at room temperature for 15-20 minutes, bake it at 80℃ for 30 minutes, and then place it at room temperature for 30 minutes before testing the pendulum hardness.

[0091] Mechanical performance testing: After the paint film is applied, it is left at room temperature for 7 days, and then the pencil hardness and adhesion (cross-cut test) are tested.

[0092] Ethanol resistance test: After the paint film is applied, it is baked at 70℃ for 30 minutes and left for 24 hours. Then, an ethanol resistance test is performed using a solvent resistance wiper, and the number of wipes is recorded.

[0093]

Example

[0094] Different polyisocyanate compositions were prepared according to the following methods and the distinguishing parameters in Table 1. The physical properties and application evaluation data of the products are shown in Table 1 and Table 2.

[0095] Step S1: Add 1000g of diisocyanate monomer to a 2L four-necked flask A, heat to 65℃ under nitrogen protection, add 2g of 5% N,N,N-trimethylbenzylammonium hydroxide isooctanol solution under stirring, and start timing. Control the reaction temperature at 65-70℃. When the reaction reaches a certain conversion rate, add 0.16g of di-n-butyl phosphate to terminate the reaction, and obtain reaction solution X.

[0096] Step S2: Add 1000g of diisocyanate monomer and 80g of isooctanol to a 2L four-necked flask B. Under nitrogen protection, heat to 120℃. Add 4g of 10% (w / w) isooctanol solution of bismuth 2-ethylhexanoate and start timing. Control the reaction temperature at 120-130℃. When the reaction reaches a certain conversion rate, add 0.64g of dibutyl phosphate to terminate the reaction and obtain reaction solution Y.

[0097] Step S3: Mix reaction solution X and reaction solution Y in a certain proportion to obtain reaction solution Z.

[0098] Step S4: Using a thin-film evaporator, the above reaction solution Z is distilled twice at 150°C and 30Pa to obtain a polyisocyanate composition with a diisocyanate monomer content of less than 0.2%.

[0099] Table 1. Process parameters and physical property data of examples / comparative examples

[0100]

[0101] Table 2. Application test data of polyisocyanate compositions in the examples / comparative examples

[0102]

[0103] As can be seen from the data in the table above, in the polyisocyanate composition, the mass fraction of polyisocyanates with a number average molecular weight of 200 or more and 500 or less relative to the polyisocyanate composition is A, and the molar ratio of urea-formate structure to isocyanurate structure is B. When A and B satisfy 0.1≤A / B≤10, the polyisocyanate composition has both low viscosity and good crosslinking properties. When used in coating compositions, the prepared paint film has a faster drying speed, better paint film hardness and solvent-resistant wiping performance, and the overall performance is significantly improved, thus showing great application potential.

[0104] The present invention has been illustrated with the above embodiments to explain the detailed method of the present invention. However, the present invention is not limited to the detailed method described above, that is, it does not mean that the present invention must rely on the detailed method described above to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A polyisocyanate composition derived from an aliphatic / aicyclic diisocyanate monomer and containing an isocyanurate structure, characterized in that: a differential absorption peak exists in a region of a number average molecular weight of 200 or more and 500 or less in a spectrum of the polyisocyanate composition obtained by gel permeation chromatography (GPC), and the mass fraction of the polyisocyanate having a number average molecular weight of 200 or more and 500 or less with respect to the polyisocyanate composition is A; the relationship between the above A and B satisfies 0.1 < A / B < 10. By nuclear magnetic carbon spectroscopy (NMR) 13 The spectrum of the polyisocyanate composition obtained by C-NMR shows that it contains a urethane structure, and the molar ratio of the urethane structure to the isocyanurate structure is B. The A is 0.5% to 5%.

2. The polyisocyanate composition according to claim 1, characterized in that The polyisocyanate composition contains an isocyanurate group, an allophanate group, an iminooxadiazinedione group and a uretdione group.

3. The polyisocyanate composition according to claim 1, characterized in that, The molar ratio of the iminooxadiazinedione group with respect to the isocyanurate structure in the polyisocyanate composition is (0.01 to 0.05):

1.

4. The polyisocyanate composition according to claim 1 or 3, characterized in that The molar ratio of the uretdione group with respect to the isocyanurate structure in the polyisocyanate composition is (0.005 to 0.02):

1.

5. The polyisocyanate composition according to claim 1 or 3, characterized in that, The viscosity at 25°C is 100 to 4000 mPa-s, preferably 500 to 3000 mPa-s.

6. The polyisocyanate composition according to claim 1, characterized in that, 7. A coating composition comprising the polyisocyanate composition according to claims 1 to 6. ​

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