A quick-drying polyisocyanate composition, a preparation method and application thereof

Abstract

The application discloses a quick-drying multi-isocyanate composition, a preparation method and application thereof. The composition is an adduct obtained by removing free monomers after reaction of trimethylolalkane and excessive hydrogenated xylylene diisocyanate, and comprises a high-functionality adduct component and a low-functionality adduct component; the ratio S1 / S2 of the high-functionality adduct component and the low-functionality adduct component is 0.3-1.5, preferably 0.36-1.43. The multi-isocyanate composition provided by the application has not only a short surface drying time, but also a short real drying time, and can realize drying of weather-resistant paint in a short time in a true sense.

Description

Technical Field

[0001] This invention relates to a polyisocyanate composition, and more particularly to a fast-drying polyisocyanate composition, its preparation method, and its application. Background Technology

[0002] Two-component polyurethane coatings are the most diverse, highest-volume, and most widely used type of polyurethane coating. With increasingly diverse downstream applications, new demands are being placed on traditional aromatic polyisocyanate curing agents. TMP-type adducts prepared using hydrogenated dimethyl phthalate (H6XDI) offer superior weather resistance and color retention compared to aromatic isocyanates, making them important in high-end applications such as outdoor products and consumer electronics. However, as more companies enter the high-end coatings market, downstream customers are increasingly focused on production costs. Since coatings require sufficient time for drying and curing, further shortening the drying time of such weather-resistant coatings would translate to higher production efficiency and cost savings for downstream customers.

[0003] Patent CN104395417B discloses a method for preparing a polyurethane curing agent based on H6XDI, which has good drying properties. However, actual tests have shown that the excellent drying properties of this product are only reflected in the short "surface drying time", while the "actual drying time" is much longer than the "surface drying time" in actual construction. Therefore, there is an urgent need for a method to further shorten the "actual drying time". Summary of the Invention

[0004] To address the above technical problems, this invention proposes a fast-drying polyisocyanate composition, its preparation method, and its application. The polyisocyanate composition proposed in this invention not only has a short surface drying time but also a short actual drying time, enabling truly rapid drying of weather-resistant coatings.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A fast-drying polyisocyanate composition is an adduct obtained by reacting trimethylol alkane with excess hydrogenated dimethyl phthalate and removing the free monomer. It comprises a high-functionality adduct component and a low-functionality adduct component; the ratio S1 / S2 of the high-functionality adduct component and the low-functionality adduct component is 0.3-1.5, preferably 0.36-1.43.

[0007] Wherein, S1 is the sum of the peak areas of the polyisocyanate composition in the GPC spectrum at retention times of 20.1-20.9 min and 21.1-22.1 min, and S2 is the peak area of ​​the polyisocyanate composition in the GPC spectrum at retention times of 22.5-23.6 min. In this invention, the aforementioned peaks specifically refer to single-peaked peaks.

[0008] The trihydroxymethyl alkane is one or more of trihydroxymethylpropane, trihydroxymethylcyclohexane, trihydroxymethylbutane, and trihydroxymethylpentane.

[0009] For TMP-type adducts using trimethylolpropane as a starting material, it is clear that the low-functionality adduct component refers to the addition product of 1 molecule of trimethylolpropane and 3 molecules of hydrogenated dimethyl phthalate (as shown in Formula I). ​​Based on the expertise of those skilled in the art, it can be reasonably inferred that the high-functionality adduct component represents the addition product of 2 molecules of trimethylolpropane and 5 molecules of hydrogenated dimethyl phthalate (as shown in Formula II) and the addition product of 3 molecules of trimethylolpropane and 7 molecules of hydrogenated dimethyl phthalate (as shown in Formula III).

[0010]

[0011] Through continuous research, the inventors have discovered that the ratio S1 / S2 of the high-functionality adduct component and the low-functionality adduct component has a crucial impact on the drying time of the applied product. When S1 / S2 falls within the range of 0.3-1.5, the paint film exhibits excellent fast-drying properties, characterized by short surface drying and complete drying times. However, when this ratio is less than 0.3, the improvement in the complete drying speed of the product is not significant; when this ratio is greater than 1.5, the surface drying speed of the product is significantly slowed down. Therefore, to solve the technical problem in this invention, the optimal range for the ratio S1 / S2 of the high-functionality adduct component and the low-functionality adduct component is 0.3-1.5.

[0012] As a preferred embodiment of the present invention, the ratio of the amount of hydrogenated dimethyl phthalate to trimethylol alkane, expressed as the molar ratio R of isocyanate group to hydroxyl group, is 4.4 ≤ R ≤ 6.5.

[0013] As a preferred embodiment of the present invention, the reaction conditions are: reaction temperature 55-100℃, preferably 60-95℃, and reaction time 3-12h, preferably 4-10h.

[0014] As a preferred embodiment of the present invention, the conditions for removing free monomers are: separation temperature of 140-190℃, preferably 140-185℃; and separation pressure of 0.1-100Pa, preferably 20-100Pa.

[0015] In a preferred embodiment of the present invention, the residual free monomer content in the composition is 0.05-0.5%, preferably 0.15-0.5%.

[0016] As a preferred embodiment of the present invention, the adduct obtained from the reaction is diluted to a solid content of 70-85% for storage and use as a fast-drying polyisocyanate composition.

[0017] As a preferred embodiment of the present invention, the solvent used for dilution is one or more of toluene, xylene, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, methylcyclohexanone, cyclohexane, n-hexane, tetrahydrofuran, chlorobenzene, dichlorobenzene, dichloromethane, dichloroethane, 1,3-dioxane, methyl acetate, ethyl acetate, butyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, ethyl propionate, propyl propionate, and butyl propionate.

[0018] A method for preparing a fast-drying polyisocyanate composition as described above, characterized in that hydrogenated dimethyl phthalate and an excess of trimethylol alkane are first reacted, and then the remaining hydrogenated dimethyl phthalate and trimethylol alkane are added in any order and without regard to the number of times, to obtain the polyisocyanate composition.

[0019] To obtain a polyisocyanate composition with an S1 / S2 ratio falling within the aforementioned range, the proportion of the high-functionality adduct component in the system can be increased. The key to increasing this proportion lies in increasing the content of the hydroxyl component. However, for TMP-type adduct products, it is known to control the excess of the NCO component to ensure complete reaction of the hydroxyl component, avoiding the presence of active hydroxyl functional groups in the system, and finally removing the excess NCO component through processes such as evaporation. Therefore, this invention employs a method of adding trimethylol alkane in steps, with an excess added in the first addition step, to increase the content of the high-functionality adduct component. This increases the proportion of the high-functionality adduct component to a certain extent in the initial reaction stage, making it easier to adjust the S1 / S2 ratio within the range of 0.3-1.5.

[0020] In a preferred embodiment of the present invention, the hydrogenated dimethyl phthalate and the excess trimethylol alkane are calculated based on the molar ratio of isocyanate groups to hydroxyl groups as R0, where 0.023 ≤ R0 ≤ 0.475.

[0021] Preferably, the hydrogenated dimethyl phthalate and excess trimethylol alkane are reacted for 1.0-4.0 h, preferably 1.2-3.5 h, before the remaining hydrogenated dimethyl phthalate and trimethylol alkane are added.

[0022] Preferably, the content of the trimethylol alkane added for the first time is 9-35% of its total mass.

[0023] As a method for preparing the polyisocyanate composition of the present invention, for example, but not limited to, the following schemes are used:

[0024] As in Scheme 1, tris(hydroxymethyl)alkane is added in two batches. First, excess tris(hydroxymethyl)alkane reacts with hydrogenated dimethyl phthalate to generate a terminal hydroxyl derivative. Then, tris(hydroxymethyl)alkane and excess hydrogenated dimethyl phthalate are added to the derivative. The reaction is completed to obtain the terminal NCO adduct reaction solution.

[0025] As in Scheme 2, tris(hydroxymethyl)alkane is added in two batches. First, excess tris(hydroxymethyl)alkane reacts with hydrogenated dimethyl phthalate to generate a terminal hydroxyl derivative. Then, excess hydrogenated dimethyl phthalate is added to the derivative. Finally, the remaining tris(hydroxymethyl)alkane is added. The reaction is complete, and the terminal NCO adduct reaction solution is obtained.

[0026] As in Scheme 3, trihydroxymethyl alkane is added in three batches. First, excess trihydroxymethyl alkane reacts with hydrogenated dimethyl phthalate to generate a terminal hydroxyl derivative. Then, a second batch of trihydroxymethyl alkane is added, along with excess hydrogenated dimethyl phthalate. After reacting for a period of time, a third batch of trihydroxymethyl alkane is finally added. The reaction is complete, and a terminal NCO adduct reaction solution is obtained.

[0027] The above preparation method is only one example of the means to control S1 / S2 to meet the requirements mentioned above, and is not intended to limit the polyisocyanate composition described in this invention. In addition, those skilled in the art can adjust S1 / S2 to meet the requirements of this invention by other possible means, such as appropriately increasing the reaction temperature.

[0028] As a further explanation of the preparation method in this invention, after the reaction is complete, the residual free NCO monomer in the system is removed by means of, for example, thin-film evaporation, so as to control the content of free monomer within the specified range. Finally, the product is diluted to 70-85% solid content at 50-85°C to obtain the polyisocyanate composition.

[0029] The preferred conditions for separating free monomers are: a separation temperature of 140-190℃, preferably 140-185℃; and a separation pressure of 0.1-100Pa, preferably 20-100Pa.

[0030] Application of a fast-drying polyisocyanate composition as described above or a fast-drying polyisocyanate composition prepared by the method described above as a coating curing agent.

[0031] The polyisocyanate composition provided by this invention has both a short surface drying time and a fast drying time, making it suitable for preparing fast-drying coating products. Detailed Implementation

[0032] 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.

[0033] The following embodiments will provide a detailed description of the method provided by the present invention. However, the present invention is not limited to the listed embodiments, but should also include any other well-known modifications within the scope of the claims of the present invention. The specific application of the present invention is not limited to the applications mentioned in the examples. Those skilled in the art can make extended modifications to the present invention through the concept of the present invention, and these simple modifications are all within the protection scope of the present invention.

[0034] The following testing method is used in the embodiments of the present invention:

[0035] (1) Test method for free isocyanate monomer content: The test was conducted using the national standard GB / T18446-2009 and an Agilent GC-7890B gas chromatograph.

[0036] (2) GPC test: The test method of gel permeation chromatography Alliance was used to test and the component ratio was calculated.

[0037] Gel permeation chromatography test method: Weigh approximately 0.05 g of sample, dissolve it in dichloromethane to prepare a 1.5 ml solution, and then determine its composition under the following conditions:

[0038] Gel chromatograph type / model: Agilent 1260;

[0039] Mobile phase: tetrahydrofuran;

[0040] Chromatographic columns: Pl1113-6520 and Pl113-6325 (Agilent);

[0041] Column packing material: phenylmethylpolysiloxane;

[0042] Detection method: Differential detector;

[0043] Flow rate 1 ml / min, pressure 93.3-98.0 bar, column temperature 35℃.

[0044] Component ratio calculation method:

[0045] The sum of the peak areas at retention times of 20.1-20.9 min and 21.1-22.1 min in the GPC spectrum is taken as S1; the peak area at retention time of 22.5-23.6 min is taken as S2. S1 / S2 is the ratio of the high-functionality adduct component to the low-functionality adduct component.

[0046] (3) Impact resistance test of the product: The polyisocyanate composition was prepared according to the coating preparation method and tested using the national standard GB / T 1732-93 and Riven's QCJ-100 paint film impact tester.

[0047] Coating preparation method: The prepared polyisocyanate composition is mixed with a polyol (ACR7502, Tongde Chemical) at a ratio of 1.0 (equivalent ratio of isocyanate groups in the polyisocyanate composition to hydroxyl groups in the polyol, NCO / OH). The mixture is then adjusted to a solid content of 50% using a mixed solvent (composition: ethyl acetate / butyl acetate = 1 / 1 / (mass ratio)).

[0048] (4) Drying performance test of the product: The polyisocyanate composition was prepared according to the above coating preparation method, and the surface drying time and actual drying time of the coating were tested.

[0049] Surface drying time test: Apply the mixture to a glass plate (JIS R3202) using a 100μm applicator. When touching the center of the coated surface, ensure that the fingertip is not contaminated with the sample (refer to JIS K 5600-1-1), and record the elapsed time as an indicator of the evaluation results.

[0050] Drying time test: Apply the mixture to a glass plate (JIS R3202) test piece using a 100μm applicator. Try to pinch the center of the test piece firmly with your thumb and forefinger until no indentation caused by fingerprints is produced on the glass coating surface and no movement of the coating film can be felt. In addition, try to rub the coating surface quickly and repeatedly with your fingertips until no friction marks are produced (refer to JIS K 5600-1-1). Record the time elapsed at this point as an indicator of the evaluation result.

[0051] The main raw materials used in the following embodiments are as follows:

[0052] Hydrogenated diphenylmethylene diisocyanate (H6XDI): Wanhua Chemical, purity >99%;

[0053] Trimethylolpropane: Pastor, purity >99%;

[0054] Polyol: ACR7502, Tongde Chemical, purity >99%;

[0055] Ethyl acetate: Aladdin reagent, purity >99%;

[0056] Butyl acetate: Aladdin reagent, purity >99%;

[0057] Unless otherwise specified, all other raw materials and reagents are available through commercial channels.

[0058] The reaction, separation, and dilution processes in the following examples and comparative examples were all carried out in an environment with sufficient dry nitrogen.

[0059]

Example 1

[0060] 5.97 g of hydrogenated phenylenediamine diisocyanate and 10.21 g of trimethylolpropane were weighed and added to a round-bottom flask. The mixture was heated in a water bath at 65 °C for 1.2 h with stirring to obtain a terminal hydroxyl derivative. Then, 494.03 g of hydrogenated phenylenediamine diisocyanate and 33.24 g of trimethylolpropane were added to the container, and the reaction was continued at 60 °C for 2.5 h with stirring to obtain a terminal NCO adduct reaction solution. The unreacted free isocyanate monomer was separated using a thin-film evaporator (separation temperature 160 °C, separation pressure 30 Pa), and the heavy component was collected and mixed with ethyl acetate to a solid content of 75%. After thorough mixing, a polyisocyanate composition was obtained.

[0061]

Example 2

[0062] 18.10 g of hydrogenated dimethyl phthalate diisocyanate and 17.53 g of trimethylolpropane were weighed and added to a round-bottom flask. The mixture was heated in a water bath at 65 °C for 4.0 h with stirring to obtain a terminal hydroxyl derivative. Then, 481.90 g of hydrogenated dimethyl phthalate diisocyanate and 34.81 g of trimethylolpropane were added to the container, and the reaction was continued at 70 °C for 3.5 h with stirring to obtain a terminal NCO adduct reaction solution. The unreacted free isocyanate monomer was separated using a thin-film evaporator (separation temperature 140 °C, separation pressure 20 Pa), and the heavy component was collected and mixed with ethyl acetate to a solid content of 75%. After thorough mixing, a polyisocyanate composition was obtained.

[0063]

Example 3

[0064] 7.31 g of hydrogenated phenylenediamine diisocyanate and 10.69 g of trimethylolpropane were weighed and added to a round-bottom flask. The mixture was heated in a water bath at 70 °C for 2.5 h with stirring to obtain a terminal hydroxyl derivative. Then, 492.69 g of hydrogenated phenylenediamine diisocyanate and 32.76 g of trimethylolpropane were added to the container, and the reaction was continued at 80 °C for 4.0 h with stirring to obtain a terminal NCO adduct reaction solution. The unreacted free isocyanate monomer was separated using a thin-film evaporator (separation temperature 180 °C, separation pressure 80 Pa), and the heavy component was collected and mixed with ethyl acetate to a solid content of 75%. After thorough mixing, a polyisocyanate composition was obtained.

[0065]

Example 4

[0066] 0.16 g of hydrogenated dimethyl phthalate diisocyanate and 3.26 g of trimethylolpropane were weighed and added to a round-bottom flask. The mixture was heated in a water bath at 55 °C for 3.0 h with stirring to obtain a terminal hydroxyl derivative. Then, 499.84 g of hydrogenated dimethyl phthalate diisocyanate and 32.17 g of trimethylolpropane were added to the container, and the reaction was continued at 70 °C for 5.0 h with stirring to obtain a terminal NCO adduct reaction solution. The unreacted free isocyanate monomer was separated using a thin-film evaporator (separation temperature 150 °C, separation pressure 50 Pa), and the heavy component was collected and mixed with ethyl acetate to a solid content of 75%. After thorough mixing, a polyisocyanate composition was obtained.

[0067]

Example 5

[0068] 11.71 g of hydrogenated phenylenediamine diisocyanate and 15.13 g of trimethylolpropane were weighed and added to a round-bottom flask. The mixture was heated in a water bath at 80 °C for 3.5 h with stirring to obtain a terminal hydroxyl derivative. Then, 488.29 g of hydrogenated phenylenediamine diisocyanate was added to the container and reacted at 95 °C for 2.0 h. Finally, 31.87 g of trimethylolpropane was added, and the reaction was continued at 95 °C for another 2.0 h with stirring to obtain a terminal NCO adduct reaction solution. The unreacted free isocyanate monomer was separated using a thin-film evaporator (separation temperature 160 °C, separation pressure 40 Pa), and the heavy component was collected and mixed with ethyl acetate to a solid content of 75%. After thorough mixing, a polyisocyanate composition was obtained.

[0069]

Example 6

[0070] Weigh 1.08 g of hydrogenated phenylenediamine diisocyanate and 5.17 g of trimethylolpropane, add them to a round-bottom flask, and heat in a water bath at 60 °C for 2.0 h while stirring to obtain a hydroxyl-terminated derivative. Then add 498.92 g of hydrogenated phenylenediamine diisocyanate and 25.23 g of trimethylolpropane to the container, and continue the reaction at 65 °C for 7.0 h. Finally, add 10.0 g of trimethylolpropane and continue the reaction at 65 °C for another 7.0 h while stirring to obtain a terminal NCO adduct reaction solution. Separate the unreacted free isocyanate monomer using a thin-film evaporator (separation temperature 190 °C, separation pressure 100 Pa), and collect the heavy component. Mix with ethyl acetate and dilute to a solid content of 75%. After stirring and mixing thoroughly, a polyisocyanate composition is obtained.

[0071]

Example 7

[0072] 3.02 g of hydrogenated phenylenediamine diisocyanate and 8.08 g of trimethylolpropane were weighed and added to a round-bottom flask. The mixture was heated in a water bath at 90 °C for 1.0 h with stirring to obtain a terminal hydroxyl derivative. Then, 496.98 g of hydrogenated phenylenediamine diisocyanate and 35.37 g of trimethylolpropane were added to the container, and the reaction was continued at 60 °C for 6.0 h with stirring to obtain a terminal NCO adduct reaction solution. The unreacted free isocyanate monomer was separated using a thin-film evaporator (separation temperature 170 °C, separation pressure 60 Pa), and the heavy component was collected and mixed with ethyl acetate to a solid content of 75%. After thorough mixing, a polyisocyanate composition was obtained.

[0073] Comparative Example 1

[0074] 500 g of hydrogenated dimethyl phthalate diisocyanate was weighed into a round-bottom flask, and 43.45 g of trimethylolpropane was added. The mixture was heated in a water bath at 65 °C for 1.2 h with stirring, and then the reaction was continued at 70 °C for 2.5 h with stirring, yielding a terminal NCO adduct reaction solution. Unreacted free isocyanate monomers were separated using a thin-film evaporator (separation temperature 170 °C, separation pressure 30 Pa), and the heavy components were collected and diluted with ethyl acetate to a solid content of 75%. After thorough mixing, a polyisocyanate composition was obtained.

[0075] Comparative Example 2

[0076] 5.97 g of hydrogenated phenylenediamine diisocyanate and 0.91 g of trimethylolpropane were weighed and added to a round-bottom flask. The mixture was heated in a water bath at 65 °C for 1.2 h with stirring to obtain a hydroxyl-terminated derivative. Then, 494.03 g of hydrogenated phenylenediamine diisocyanate and 42.54 g of trimethylolpropane were added to the container, and the reaction was continued at 60 °C for 2.5 h with stirring to obtain a NCO-terminated derivative reaction solution. Unreacted isocyanate monomers in the reaction solution were separated using a thin-film evaporator (separation temperature 160 °C, separation pressure 30 Pa), and the heavy components were collected and diluted with ethyl acetate to a solid content of 75%. After thorough mixing, a polyisocyanate composition was obtained.

[0077] Comparative Example 3

[0078] 5.97 g of hydrogenated phenylenediamine diisocyanate and 42.21 g of trimethylolpropane were weighed and added to a round-bottom flask. The mixture was heated in a water bath at 65 °C for 1.2 h with stirring to obtain a hydroxyl-terminated derivative. Then, 494.03 g of hydrogenated phenylenediamine diisocyanate and 1.24 g of trimethylolpropane were added to the container, and the reaction was continued at 60 °C for 2.5 h with stirring to obtain a NCO-terminated derivative reaction solution. Unreacted isocyanate monomers in the reaction solution were separated using a thin-film evaporator (separation temperature 160 °C, separation pressure 30 Pa), and the heavy components were collected and diluted with ethyl acetate to a solid content of 75%. After thorough mixing, a polyisocyanate composition was obtained.

[0079] Table 1. Basic Indicators and Performance Test Results of Examples and Comparative Examples

[0080]

[0081] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and additions without departing from the method of the present invention, and these improvements and additions should also be considered within the scope of protection of the present invention.

Claims

1. A fast-drying polyisocyanate composition, characterized in that, The adduct is obtained by reacting trimethylolpropane with hydrogenated phenylene diisocyanate and removing the free monomer, comprising a high-functionality adduct component and a low-functionality adduct component; the ratio S1 / S2 of the high-functionality adduct component and the low-functionality adduct component is 0.3-1.

5. The low-functionality adduct component refers to the addition product of 1 molecule of trimethylolpropane and 3 molecules of hydrogenated dimethyl phthalate, while the high-functionality adduct component represents the addition product of 2 molecules of trimethylolpropane and 5 molecules of hydrogenated dimethyl phthalate and the addition product of 3 molecules of trimethylolpropane and 7 molecules of hydrogenated dimethyl phthalate. Wherein, S1 is the sum of the signal peak areas of the polyisocyanate composition at retention times of 20.1-20.9 min and 21.1-22.1 min in the GPC spectrum, and S2 is the signal peak area of ​​the polyisocyanate composition at retention times of 22.5-23.6 min in the GPC spectrum.

2. The fast-drying polyisocyanate composition according to claim 1, characterized in that, The ratio S1 / S2 of the high-functionality adduct component and the low-functionality adduct component is 0.36-1.

43.

3. The fast-drying polyisocyanate composition according to claim 1, characterized in that, The ratio of hydrogenated dimethyl phthalate to trimethylolpropane, expressed as the molar ratio R of isocyanate groups to hydroxyl groups, is 4.4 ≤ R ≤ 6.

5.

4. The fast-drying polyisocyanate composition according to claim 3, characterized in that, The reaction conditions are: reaction temperature 55-100℃, reaction time 3-12h.

5. The fast-drying polyisocyanate composition according to claim 4, characterized in that, The reaction conditions are: reaction temperature 60-95℃, reaction time 4-10h.

6. The fast-drying polyisocyanate composition according to any one of claims 1-5, characterized in that, The conditions for removing free monomers are: separation temperature 140-190℃; separation pressure 0.1-100Pa.

7. The fast-drying polyisocyanate composition according to claim 6, characterized in that, The conditions for removing free monomers are: separation temperature 140-185℃; separation pressure 20-100Pa.

8. The fast-drying polyisocyanate composition according to claim 6, characterized in that, The residual free monomer content in the composition is 0.05-0.5%.

9. The fast-drying polyisocyanate composition according to claim 8, characterized in that, The composition contains 0.15-0.5% residual free monomer.

10. The fast-drying polyisocyanate composition according to claim 6, characterized in that, The adduct obtained from the reaction is diluted to a solid content of 70-85% and stored as a fast-drying polyisocyanate composition.

11. A method for preparing a fast-drying polyisocyanate composition according to any one of claims 1-10, characterized in that, First, hydrogenated dimethyl phthalate diisocyanate and excess trimethylolpropane are reacted. Then, the remaining hydrogenated dimethyl phthalate diisocyanate and trimethylolpropane are added in any order and without regard to the number of times, and the reaction is carried out to obtain the polyisocyanate composition.

12. The method for preparing the fast-drying polyisocyanate composition according to claim 11, characterized in that, Hydrogenated dimethyl phthalate and excess trimethylolpropane are calculated based on the molar ratio of isocyanate groups to hydroxyl groups as R0, where 0.023 ≤ R0 ≤ 0.

475.

13. The method for preparing the fast-drying polyisocyanate composition according to claim 12, characterized in that, First, react hydrogenated dimethyl phthalate with excess trimethylolpropane for 1.0-4.0 h, then add the remaining hydrogenated dimethyl phthalate and trimethylolpropane.

14. The method for preparing the fast-drying polyisocyanate composition according to claim 13, characterized in that, First, react hydrogenated dimethyl phthalate with excess trimethylolpropane for 1.2-3.5 hours, then add the remaining hydrogenated dimethyl phthalate and trimethylolpropane.

15. The use of a fast-drying polyisocyanate composition as described in any one of claims 1-10 or a fast-drying polyisocyanate composition prepared by the method described in any one of claims 11-14 as a coating curing agent.

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