Polyisocyanate composition as well as preparation method and application thereof

Abstract

The invention relates to a polyisocyanate composition as well as a preparation method and application thereof, and the polyisocyanate composition comprises the following components in percentage by mass: 45-56% of an aliphatic isocyanate tripolymer, 16-23% of allophanate and an aliphatic isocyanate pentamer, 23%, an aliphatic isocyanate polymer lt; and 13%. The color value and the viscosity of the polyisocyanate composition provided by the invention are relatively low, and the content of the aliphatic isocyanate tripolymer is relatively high.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic synthesis, and particularly relates to a polyisocyanate composition, a preparation method thereof, and an application thereof. Background Art

[0002] Polyurethane coatings have the characteristics of good film appearance, excellent mechanical properties and chemical resistance, and are widely used in the coating and protection of woodware, automobiles, buildings, railways, etc., with broad prospects. Isocyanate curing agents are key components of polyurethane coatings, and aliphatic polyisocyanate compositions are one of the important development directions of isocyanate curing agents. However, there are still many problems with the existing aliphatic polyisocyanate compositions. In addition to the low content of the target component aliphatic isocyanate trimer, the proportion of other polymers is relatively large, resulting in high product viscosity, high chromaticity, and unstable storage.

[0003] The preparation of aliphatic polyisocyanate compositions usually uses quaternary ammonium salts or quaternary ammonium hydroxides as catalysts. The catalytic activity of quaternary ammonium salts or quaternary ammonium hydroxides is high. If a kettle reactor is used, there are certain requirements for the dropping rate of the catalyst. During the dropping process of the catalyst, local high concentration or poor dispersion effect is likely to generate high polymers, resulting in large lumps of glue or runaway temperature in the system; if the dropping rate is too slow, it is likely that the reaction cannot be initiated or the reaction time is too long, leading to a decline in product performance. And the polymerization reaction is a highly exothermic reaction, and uneven heat exchange is likely to cause the reaction to get out of control. The kettle polymerization reaction with high requirements for the heat exchange system is likely to generate high polymers, and the proportion of aliphatic isocyanate trimer is relatively low, and the product viscosity is high; moreover, the kettle reactor cannot carry out continuous production.

[0004] The prior art designs the components of the catalyst to increase the content of aliphatic isocyanate trimer in the product. For example, CN115672398A discloses a catalyst and a synthesis method of hexamethylene diisocyanate trimer. The catalyst includes: a phosphorus-containing organic compound and a quaternary ammonium hydroxide, wherein the phosphorus-containing organic compound is selected from tripropylphosphine and / or tributylphosphine, and the quaternary ammonium hydroxide is selected from one or more of the group consisting of triethylbenzylammonium hydroxide, cetyltrimethylammonium hydroxide, trimethylbenzylammonium hydroxide, and tetramethylammonium hydroxide. However, a product with a high content of aliphatic isocyanate trimer and a low color value cannot be obtained only by improving the catalyst.

[0005] In view of this, it is necessary to design a polyisocyanate composition with a low color value, a relatively high content of aliphatic isocyanate trimer, and a relatively low viscosity, as well as its preparation process. Summary of the Invention

[0006] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a polyisocyanate composition, a preparation method thereof, and an application thereof. Through the design of each component and its dosage, the polyisocyanate composition has the advantages of being clear, having a relatively low viscosity, and a high content of aliphatic isocyanate trimer.

[0007] To achieve this purpose, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a polyisocyanate composition. In terms of mass percentage content, the polyisocyanate composition comprises the following components:

[0009]

[0010] The mass percentage content of the aliphatic isocyanate trimer is 45 - 56%, for example, it can be 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, etc.

[0011] The mass percentage content of the urethane is 16 - 23%, for example, it can be 16.5%, 17%, 17.5%, 18%, 18.5%, 19%, 19.5%, 20%, 20.5%, 21%, 21.5%, 22%, 22.5%, etc.

[0012] The mass percentage content of the aliphatic isocyanate pentamer < 23%, for example, it can be 0.5%, 1%, 1.5%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 17.5%, 18%, 18.5%, 19%, 19.5%, 20%, 20.5%, 21%, 21.5%, 22%, 22.5%, etc.

[0013] The mass percentage content of the aliphatic isocyanate polymer < 13%, for example, it can be 0.5%, 1%, 1.5%, 2%, 3%, 4%, 5%, 6%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, 10.5%, 11%, 11.5%, 12%, 12.5%, etc.

[0014] In the present invention, the aliphatic isocyanate trimer refers to a substance obtained by self - polymerization of three aliphatic isocyanate molecules; the aliphatic isocyanate pentamer refers to a substance obtained by self - polymerization of five aliphatic isocyanate molecules; the aliphatic isocyanate polymer refers to a substance obtained by self - polymerization of at least seven aliphatic isocyanate molecules.

[0015] The following are the preferred technical solutions of the present invention, but do not limit the technical solutions provided by the present invention. Through the following preferred technical solutions, the purpose and beneficial effects of the present invention can be better achieved and realized.

[0016] As a preferred technical solution, the aliphatic isocyanate trimer includes any one of pentamethylene diisocyanate trimer, hexamethylene diisocyanate trimer or isophorone diisocyanate trimer, or a combination of at least two of them.

[0017] Preferably, the aliphatic isocyanate pentamer includes any one of pentamethylene diisocyanate pentamer, hexamethylene diisocyanate pentamer or isophorone diisocyanate pentamer, or a combination of at least two thereof.

[0018] Preferably, the aliphatic isocyanate polymer includes any one of pentamethylene diisocyanate polymer, hexamethylene diisocyanate polymer or isophorone diisocyanate polymer, or a combination of at least two thereof.

[0019] Preferably, the allophanate has a structure as shown in Formula I:

[0020]

[0021] Wherein, R1 and R2 are each independently selected from n-pentylene, n-hexylene or Any one of; "*-" represents the connection site of the group; R3 is selected from any one of C1-C10 straight or branched alkyl.

[0022] In the present invention, the C1-C10 (e.g., C3, C4, C5, C6, C7, C8, C9) straight chain or branched alkyl groups illustratively include but are not limited to: methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, 2-methylbutyl, n-pentyl, isopentyl, neopentyl, n-hexyl, neohexyl, 2-ethylhexyl, n-octyl, n-heptyl, n-nonyl, n-decyl, etc.

[0023] Preferably, the color value of the polyisocyanate composition is less than 20HZ, for example, it can be 0.5HZ, 1HZ, 2HZ, 3HZ, 4HZ, 5HZ, 6HZ, 7HZ, 8HZ, 9HZ, 10HZ, 10.5HZ, 11HZ, 11.5HZ, 12HZ, 12.5HZ, 13HZ, 13.5HZ, 14HZ, 14.5HZ, 15HZ, 15.5HZ, 16HZ, 16.5HZ, 17HZ, 17.5HZ, 18HZ, 18.5HZ, 19HZ, 19.5HZ, etc.

[0024] Preferably, the viscosity of the polyisocyanate composition is < 2500 cP (e.g., it can be 1400 cP, 1450 cP, 1500 cP, 1550 cP, 1600 cP, 1650 cP, 1700 cP, 1750 cP, 1800 cP, 1850 cP, 1900 cP, 1950 cP, 2000 cP, 2050 cP, 2100 cP, 2150 cP, 2200 cP, 2250 cP, 2300 cP, 2350 cP, 2400 cP, 2450 cP, etc.), and more preferably 1400 - 2000 cP.

[0025] Preferably, the light transmittance of the polyisocyanate composition is 99.5 - 100%, e.g., it can be 99.55%, 99.6%, 99.65%, 99.7%, 99.75%, 99.8%, 99.85%, 99.9%, 99.95%, etc.

[0026] In the present invention, the test method for the urethane, aliphatic isocyanate trimer, aliphatic isocyanate pentamer, and aliphatic isocyanate heptamer structures adopts 13 C - NMR nuclear magnetic resonance method; the instrument used is a Bruker 400 MHz instrument, the sample concentration is 6% (CDCl3 solution), and δ = 77.0 ppm CDCl3 is used as the chemical shift reference.

[0027] In the second aspect, the present invention provides a preparation method of the polyisocyanate composition as described in the first aspect, and the preparation method includes the following steps:

[0028] (1) Add the aliphatic isocyanate and the catalyst composite system into a microchannel reactor, and carry out the reaction under the condition of 60 - 100 °C to obtain a reaction solution; the catalyst composite system includes a combination of a catalyst and an alcohol solvent;

[0029] (2) Perform post - treatment on the reaction solution to obtain the polyisocyanate composition.

[0030] Microchannel reactors have high mass and heat transfer capabilities, with small and stable fluctuations in reaction temperature, and have advantages such as small volume, low consumption, scalability, and high safety. Microchannel reactors use continuous flow feeding, which is convenient for initiating or terminating reactions, and the reaction process is easy to control, greatly improving the safety of production. However, microchannel reactors have the defects of easy channel blockage and difficulty in cleaning, so they are usually difficult to handle reactions involving solid particles or high-viscosity fluids. In the preparation of polyisocyanate compositions, which belong to polymerization reactions, if the reaction residence time is short, due to insufficient catalyst dispersion, a large amount of solids will be generated locally. If the reaction residence time is long, a large amount of heat is not easily released, which will lead to excessive polymerization and generate more polymers, resulting in a high viscosity of the product. Therefore, it is difficult to directly use a microchannel reactor to prepare polyisocyanate compositions. If it is combined with a kettle reactor, that is, first use the microchannel reactor to mix and initially react at low temperature, and then the reaction solution flows out to the kettle reactor for high-temperature polymerization. Although it can improve the viscosity to a certain extent, it requires switching reactions, with low overall efficiency and still a relatively high viscosity of the product. The present inventors have found that instead of controlling the low temperature, the reaction temperature is actively increased to allow the reaction to proceed rapidly, while controlling a short residence time, and using an alcohol solvent to dilute the catalyst. Since the alcohol solvent reacts with the raw material aliphatic isocyanate to produce a by-product of urethane, it can effectively reduce the viscosity of the polyisocyanate composition. In the presence of the alcohol solvent, in addition to the aliphatic isocyanate trimer in the product, it is mainly the aliphatic isocyanate pentamer and aliphatic isocyanate heptamer, with controllable viscosity, making it practical to continuously produce polyisocyanate compositions using a microchannel reactor. The present invention prepares polyisocyanate compositions through a microchannel reactor, which can be carried out continuously without switching pipelines and reaction kettles, reducing the operation process, improving production efficiency, and reducing the polymer impurities in the target product; the prepared polyisocyanate composition has the advantages of low viscosity, low color value, and high content of aliphatic isocyanate trimer.

[0031] The polyisocyanate composition obtained by the preparation method provided by the present invention contains a high proportion of urethane and aliphatic isocyanate trimer. The urethane is a by-product obtained by the reaction of an alcohol solvent in the catalyst composite system with an aliphatic isocyanate, and has the structure shown in Formula I; the present invention generates urethane by reacting an alcohol solvent with an aliphatic isocyanate, which can effectively reduce the viscosity of the product, reduce the generation of polymer impurities, and thus can significantly reduce the viscosity of the polyisocyanate composition; and the urethane has the characteristics of high saturated vapor pressure, low toxicity, and low volatility. Due to its low functionality, the polyisocyanate composition has good flexibility and good low-temperature resistance, and is suitable for application scenarios with high requirements for low-temperature flexibility.

[0032] Preferably, the aliphatic isocyanate includes any one or a combination of at least two of pentamethylene diisocyanate, hexamethylene diisocyanate, or isophorone diisocyanate.

[0033] Preferably, the catalyst includes quaternary ammonium salts and / or quaternary ammonium bases.

[0034] Preferably, the quaternary ammonium salt includes 2-hydroxypropyltrimethyl formate ammonium salt and / or 2-hydroxypropyltrimethyl isooctanoate ammonium salt.

[0035] Preferably, the quaternary ammonium base includes any one or a combination of at least two of tetramethylammonium hydroxide, tetrabutylammonium hydroxide, or benzyltrimethylammonium hydroxide.

[0036] Preferably, the alcohol solvent includes primary alcohols; the structure of the primary alcohol is: R-OH; R is selected from any one of C1-C10 straight-chain or branched-chain alkyl groups. Using primary alcohols can achieve a faster reaction rate and better product dispersibility.

[0037] Preferably, the primary alcohol is methanol.

[0038] Preferably, the mass percentage content of the catalyst in the catalyst composite system is 10-25%, for example, it can be 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, etc.

[0039] Preferably, based on the mass of the aliphatic isocyanate being 100%, the mass of the catalyst composite system is 0.1-3% (for example, it can be 0.1%, 0.2%, 0.4%, 0.6%, 0.8%, 1%, 1.2%, 1.4%, 1.6%, 1.8%, 2%, 2.5%, 3%, etc.), and more preferably 0.6-1.3%.

[0040] Preferably, the feeding rate of the aliphatic isocyanate is 10-100 mL / min (for example, it can be 15 mL / min, 20 mL / min, 25 mL / min, 30 mL / min, 35 mL / min, 40 mL / min, 45 mL / min, 50 mL / min, 55 mL / min, 60 mL / min, 65 mL / min, 70 mL / min, 75 mL / min, 80 mL / min, 85 mL / min, 90 mL / min, 95 mL / min, etc.), and more preferably 10-50 mL / min.

[0041] Preferably, the catalyst composite system is added into the microchannel reactor by dropping, and the dropping rate of the catalyst composite system is 5-50 mL / h (for example, it can be 8 mL / h, 10 mL / h, 12 mL / h, 15 mL / h, 18 mL / h, 20 mL / h, 22 mL / h, 25 mL / h, 28 mL / h, 30 mL / h, 32 mL / h, 35 mL / h, 38 mL / h, 40 mL / h, 42 mL / h, 45 mL / h, 48 mL / h, etc.), and more preferably 10-30 mL / h. By dropping the catalyst composite system and controlling the dropping rate, it can effectively avoid local agglomeration and excessive polymerization caused by uneven dispersion of the catalyst, thereby blocking the pipeline or being difficult to flow due to too high viscosity.

[0042] Preferably, an inhibitor is added during the progress of the reaction in step (1); in the present invention, the progress of the reaction means the residence period of the aliphatic isocyanate and the catalyst composite system in the microchannel reactor or the moment when the aliphatic isocyanate and the catalyst composite system reach the longest residence time in the microchannel reactor.

[0043] Preferably, the inhibitor includes any one or a combination of at least two of phosphoric acid, benzoic acid, benzoyl chloride, bis(2-ethylhexyl) phosphate, dibutyl phosphate or dimethyl phosphate.

[0044] Preferably, the mass ratio of the inhibitor to the catalyst is (1-2):1, for example, it can be 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, etc.

[0045] In the present invention, the mass ratio of the inhibitor to the catalyst refers to the ratio of the amount of the inhibitor used to the amount of the catalyst used during the entire product preparation process.

[0046] Preferably, the inhibitor is added into the microchannel reactor by dropping, and the dropping rate of the inhibitor is calculated according to the following formula:

[0047] V 阻聚剂 =(1.2-2)×V×ρ1×α / ρ2;

[0048] wherein, V represents the feeding rate of the catalyst composite system, with the unit of mL / h.

[0049] ρ1 represents the density of the catalyst composite system, with the unit of g / cm 3 .

[0050] ρ2 represents the density of the inhibitor, with the unit of g / cm 3 .

[0051] a represents the mass percentage of the catalyst in the catalyst composite system.

[0052] By controlling the feeding rate of the aliphatic isocyanate and the dropping rate of the catalyst, and simultaneously controlling the dropping rate of the inhibitor according to the dropping rate of the catalyst composite system, the reaction rate and residence time are controlled to obtain reaction liquids with different outlet conversion rates.

[0053] In the present invention, the inhibitor can be directly added into the microchannel reactor, or added into the microchannel reactor after being diluted with a solvent; the solvent can be the raw material aliphatic isocyanate.

[0054] Preferably, the inner diameter of the channels of the microchannel reactor is 0.05 - 10 mm (for example, it can be 0.1 mm, 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, 5.5 mm, 6 mm, 6.5 mm, 7 mm, 7.5 mm, 8 mm, 8.5 mm, 9 mm, 9.5 mm, etc.), and more preferably 0.1 - 0.3 mm.

[0055] Preferably, the material of the microchannel reactor includes at least one of Hastelloy, titanium alloy, stainless steel, polytetrafluoroethylene or ceramic.

[0056] Preferably, the type of the microchannel reactor includes any one of a scale-type microchannel reactor, a fin-type microchannel reactor, a gourd-type microchannel reactor, a circular microchannel reactor or a triangular microchannel reactor.

[0057] Preferably, the temperature of the reaction is 60 - 100 °C (for example, it can be 62 °C, 65 °C, 68 °C, 70 °C, 72 °C, 75 °C, 78 °C, 80 °C, 82 °C, 85 °C, 88 °C, 90 °C, 92 °C, 95 °C, 98 °C or any value between any two of the above numerical ranges), and preferably 60 - 80 °C.

[0058] Preferably, the residence time of the aliphatic isocyanate and the catalyst composite system in the microchannel reactor is 1 - 60 min (for example, it can be 5 min, 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min or any value between any two of the above numerical ranges), and preferably 3 - 20 min.

[0059] Preferably, the post-treatment includes thin-film evaporation and / or molecular distillation carried out in sequence.

[0060] Preferably, the thin-film evaporation includes any one of primary thin-film evaporation, secondary thin-film evaporation or tertiary thin-film evaporation.

[0061] Preferably, when the thin-film evaporation is primary thin-film evaporation, the separation temperature is 90-150°C, the primary condensation temperature is -20 to -30°C, the secondary condensation temperature is -20 to -30°C, and the pressure is 0.1-200 Pa.

[0062] Preferably, when the thin-film evaporation is secondary thin-film evaporation, the primary separation temperature is 90-150°C and the pressure is 10-200 Pa; the secondary separation temperature is 90-150°C and the pressure is 0.1-100 Pa.

[0063] Preferably, the separation temperature of the molecular distillation is 90-150°C and the pressure is 0.1-200 Pa.

[0064] Preferably, the preparation method specifically includes the following steps:

[0065] (1) Add the aliphatic isocyanate into the microchannel reactor at a rate of 10-100 mL / min, and at the same time, drop the catalyst composite system into the microchannel reactor at a rate of 5-50 mL / h, and then react under the condition of 60-100°C. During the reaction process, add the inhibitor dropwise into the microchannel reactor; the residence time of the aliphatic isocyanate and the catalyst composite system in the microchannel reactor is 1-60 min; after the reaction is completed, a reaction solution is obtained; the catalyst composite system includes a combination of a catalyst and an alcohol solvent; the mass percentage of the catalyst in the catalyst composite system is 10-25%; based on the mass of the aliphatic isocyanate being 100%, the mass of the catalyst composite system is 0.1-3%, and the mass ratio of the inhibitor to the catalyst is (1-2):1; the dropping rate of the inhibitor is calculated according to the following formula:

[0066] V 阻聚剂 =(1.2-2)×V×ρ1×α / ρ2;

[0067] Wherein, V represents the dropping rate of the catalyst composite system, and the unit is mL / h;

[0068] ρ1 represents the density of the catalyst composite system, and the unit is g / cm 3 ;

[0069] ρ2 represents the density of the inhibitor, and the unit is g / cm 3 ;

[0070] α represents the mass percentage of the catalyst in the catalyst composite system;

[0071] (2) Perform thin-film evaporation and / or molecular distillation on the reaction solution to obtain the polyisocyanate composition.

[0072] In the present invention, when preparing a polyisocyanate composition using multiple (at least two) microchannel reactors, the multiple (at least two) microchannel reactors can be arranged in series or in parallel. Arranging them in series can increase the residence time of the reaction, and arranging them in parallel can increase the total throughput.

[0073] The actual number of microchannel reactors = N 理论 ×(1 + redundancy factor);

[0074] wherein, the redundancy factor = 0.2 - 0.3;

[0075] N 理论 = Qtotal / Qsingle;

[0076] Qtotal represents the total feeding rate of the aliphatic isocyanate; Qsingle = V1 / τ; V1 represents the effective volume of a single microchannel reactor; τ represents the residence time of the composite system of the aliphatic isocyanate and the catalyst.

[0077] In a third aspect, the present invention provides an application of the polyisocyanate composition as described in the first aspect in a polyurethane coating.

[0078] The numerical ranges described in the present invention not only include the above-listed point values, but also include any point values between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the described ranges.

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

[0080] Through the design of the components and dosages of the polyisocyanate composition, the present invention enables the polyisocyanate composition to have relatively low color value and viscosity, and a relatively high content of aliphatic isocyanate trimer; wherein the color value of the polyisocyanate composition is 14.5 - 21.5 HZ, the viscosity is 1400 - 1700 cP, and the light transmittance is 99.8 - 100%. Specific Embodiments

[0081] To facilitate the understanding of the present invention, the following examples are listed. Those skilled in the art should understand that the examples are only for helping to understand the present invention and should not be regarded as specific limitations to the present invention.

[0082] In the following examples, the testing methods for the structures of urethane, aliphatic isocyanate trimer, aliphatic isocyanate pentamer, and aliphatic isocyanate heptamer (aliphatic isocyanate polymer) are 13 C-NMR nuclear magnetic resonance method; the instrument used is a Bruker 400 MHz instrument, the sample concentration is 6% (CDCl3 solution), and δ = 77.0 ppm CDCl3 is used as the chemical shift reference.

[0083] Example 1

[0084] A polyisocyanate composition, in terms of mass percentage, comprises the following components:

[0085]

[0086] The structure of the urethane A is as follows:

[0087]

[0088] The preparation method of the polyisocyanate composition comprises the following steps:

[0089] (1) Add pentamethylene diisocyanate (PDI) into a scale microchannel reactor (5 microchannel reaction plates, inner diameter of the microchannel is 0.2 mm, total liquid storage capacity is 48.8 mL, and the material is 316L) preheated to 60°C at a speed of 10 mL / min. At the same time, a catalyst composite system with a density of 0.81 g / cm 3 (composed of 2-hydroxypropyltrimethylammonium formate and methanol, and the mass ratio of the two is 1:5) is dropped into the scale microchannel reactor at a speed of 10 mL / h for reaction. Control the residence time of PDI and the catalyst composite system in the scale microchannel reactor to be 4.9 min; at one end of the reaction liquid outlet close to the scale microchannel reactor, dibutyl phosphate with a density of 1.13 g / cm 3 is continuously dropped into the scale microchannel reactor at a speed of 1.4 mL / h; after continuous feeding for 100 min, stop feeding to obtain a reaction liquid, and its color value and outlet conversion rate are shown in Table 1;

[0090] The dropping speed of the inhibitor is calculated according to the following formula:

[0091] V 阻聚剂 = 1.2×10×0.81 / 6 / 1.13 = 1.4 mL / h;

[0092] (2) The reaction liquid is successively subjected to primary thin-film evaporation and molecular distillation. The separation temperature of the primary thin-film evaporation is 100°C, the primary condensation temperature is -30°C, the secondary condensation temperature is -20°C, and the pressure is 20 Pa; the separation temperature of the molecular distillation is 100°C, the primary condensation temperature is -30°C, the secondary condensation temperature is -20°C, and the pressure is 8 Pa. After the post-treatment, the polyisocyanate composition is obtained;

[0093] Pentamethylene diisocyanate trimer, pentamethylene diisocyanate pentamer, pentamethylene diisocyanate heptamer (pentamethylene diisocyanate polyisocyanate): (100 MHz, CDCl3); δ 23.7 ppm, 27.1 ppm, 30.7 ppm, 42.7 ppm, 149.0 ppm;

[0094] Urethane A: (100 MHz, CDCl3); δ 154.4 ppm.

[0095] Example 2

[0096] A polyisocyanate composition, the components of which are shown in Table 1, wherein the structure of urethane B is as follows:

[0097]

[0098] The preparation method of the polyisocyanate composition comprises the following steps:

[0099] (1) Add hexamethylene diisocyanate (HDI) to a scaled microchannel reactor (12 microchannel reaction plates, inner diameter of the microchannel is 0.2 mm, total liquid storage capacity is 244 mL, and the material is Hastelloy) preheated to 70 °C at a speed of 30 mL / min. At the same time, a catalyst composite system with a density of 0.795 g / cm 3 (composed of 2-hydroxypropyltrimethylammonium isooctanoate and ethanol, and the mass ratio of the two is 1:9) is added dropwise to the scaled microchannel reactor at a speed of 20 mL / h for reaction, and the residence time of HDI and the catalyst composite system in the scaled microchannel reactor is controlled to be 8.1 min; at one end near the reaction liquid outlet of the scaled microchannel reactor, a polymerization inhibitor bis(2-ethylhexyl) phosphate with a density of 0.965 g / cm 3 is added dropwise to the scaled microchannel reactor at a speed of 1.98 mL / h; after continuous feeding for 60 min, the feeding is stopped to obtain a reaction liquid, and its color value and outlet conversion rate are shown in Table 1;

[0100] The dropping speed of the polymerization inhibitor is calculated according to the following formula:

[0101] V 阻聚剂 = 1.2 × 20 × 0.795 / 10 / 0.965 = 1.98 mL / h;

[0102] (2) The reaction liquid is subjected to secondary thin-film evaporation, the first separation temperature is 120 °C, the pressure is 30 Pa, the second separation temperature is 120 °C, and the pressure is 10 Pa; then molecular distillation is carried out, the separation evaporation temperature is 120 °C, the first condensation temperature is -30 °C, the second condensation temperature is -20 °C, and the pressure is 6 Pa. After the molecular distillation is completed, the polyisocyanate composition is obtained;

[0103] Hexamethylene diisocyanate trimer, hexamethylene diisocyanate pentamer, hexamethylene diisocyanate heptamer (hexamethylene diisocyanate polyisocyanate): (100 MHz, CDCl3); δ 25.6 ppm, 26.6 ppm, 32.8 ppm, 43.8 ppm, 149.3 ppm;

[0104] Urethane B: (100 MHz, CDCl3); δ 154.4 ppm.

[0105] Example 3

[0106] A polyisocyanate composition, the components of which are shown in Table 1, wherein the structure of urethane C is as follows, where both R1 and R2 are

[0107]

[0108] The preparation method of the polyisocyanate composition comprises the following steps:

[0109] (1) Isophorone diisocyanate (IPDI) was added to a scaled microchannel reactor (12 microchannel reaction plates, inner diameter of the microchannel is 0.3 mm, total liquid storage capacity is 244 mL, and the material is 316L) preheated to 80 °C at a rate of 50 mL / min. At the same time, a catalyst composite system with a density of 0.792 g / cm 3 (composed of tetramethylammonium hydroxide and n-pentanol, and the mass ratio of the two is 1:7) was added dropwise to the scaled microchannel reactor at a rate of 30 mL / h for reaction, and the residence time of IPDI and the catalyst composite system in the scaled microchannel reactor was controlled to be 4.88 min; at one end near the reaction liquid outlet of the microchannel reactor, benzoyl chloride with a density of 1.211 g / cm 3 was added dropwise to the scaled microchannel reactor at a rate of 4.9 mL / h; after continuous feeding for 30 min, the feeding was stopped to obtain a reaction liquid, and its color value and outlet conversion rate are shown in Table 1;

[0110] The dropping rate of the inhibitor is calculated according to the following formula:

[0111] V 阻聚剂 = 1.2×50×0.792 / 8 / 1.211 = 4.9 mL / h;

[0112] (2) The reaction solution is subjected to secondary thin-film evaporation. The temperature of the first-stage separation is 130 °C, and the pressure is 35 Pa. The temperature of the second-stage separation is 130 °C, and the pressure is 20 Pa. Then, molecular distillation is carried out. The separation evaporation temperature is 130 °C, the temperature of the first-stage condensation is -30 °C, the temperature of the second-stage condensation is -20 °C, and the pressure is 20 Pa. After the molecular distillation is completed, the polyisocyanate composition is obtained.

[0113] Isophorone diisocyanate trimer, isophorone diisocyanate pentamer, isophorone diisocyanate heptamer (isophorone diisocyanate polymer): (100 MHz, CDCl3); δ 14.8 ppm, 22.5 ppm, 25.7 ppm, 32.0 ppm, 40.1 ppm, 48.3 ppm, 56.3 ppm, 59.0 ppm, 150.7 ppm;

[0114] Urethane C: (100 MHz, CDCl3); δ 154.4 ppm.

[0115] Example 4

[0116] A polyisocyanate composition, the components of which are shown in Table 1. The preparation method of the polyisocyanate composition is only different from that of Example 1 in that the reaction temperature in step (1) is 80 °C, and the other raw materials, process parameters and steps are the same as those in Example 1.

[0117] Example 5

[0118] A polyisocyanate composition and its preparation method, which are only different from those of Example 1 in that the reaction temperature in step (1) is 100 °C, and the other raw materials, process parameters and steps are the same as those in Example 1. The color value and outlet conversion rate of the reaction solution obtained in step (1) of this example are shown in Table 1.

[0119] Comparative Example 1

[0120] A polyisocyanate composition, the components of which are shown in Table 1. The preparation method of the polyisocyanate composition includes the following steps:

[0121] (1) Add 1 kg of pentamethylene diisocyanate to the reaction kettle, and drop 6 g of the catalyst composite system (composed of 2-hydroxypropyltrimethylformate ammonium salt and methanol, and the mass ratio of the two is 1:5) into the reaction kettle at a speed of 72 mL / h, and react at 60 °C for 40 min to obtain a reaction solution, and its color value and outlet conversion rate are shown in Table 1;

[0122] (2) The reaction solution is subjected to secondary thin-film evaporation. The temperature of the first-stage separation is 100 °C and the pressure is 15 Pa; the temperature of the second-stage separation is 100 °C and the pressure is 10 Pa. Then, molecular distillation is carried out. The separation evaporation temperature is 100 °C, the temperature of the first-stage condensation is -30 °C, the temperature of the second-stage condensation is -20 °C, and the pressure is 8 Pa. After the molecular distillation is completed, the polyisocyanate composition is obtained.

[0123] Comparative Example 2

[0124] A polyisocyanate composition and its preparation method, the difference from Example 1 is only that the reaction temperature in step (1) is 50 °C, and the other raw materials, process parameters and steps are the same as those in Example 1; the color value and outlet conversion rate of the reaction solution obtained in step (1) of this comparative example are shown in Table 1.

[0125] Comparative Example 3

[0126] A polyisocyanate composition, the components of which are shown in Table 1. The difference between the preparation method of the polyisocyanate composition and Example 1 is only that the dropping rate of the catalyst composite system in step (1) is 0.8 mL / h, and the dropping rate of the inhibitor is 0.11 mL / h. The other raw materials, process parameters and steps are the same as those in Example 1; the color value and outlet conversion rate of the reaction solution obtained in step (1) of this example are shown in Table 1.

[0127] Comparative Example 4

[0128] A polyisocyanate composition, the components of which are shown in Table 1. The difference between the preparation method of the polyisocyanate composition and Example 1 is only that the dropping rate of the catalyst composite system dosage in step (1) is 24 mL / h, and the dropping rate of the inhibitor is 3.44 mL / h. The other raw materials, process parameters and steps are the same as those in Example 1; the color value and outlet conversion rate of the reaction solution obtained in step (1) of this example are shown in Table 1.

[0129] Product Index Test

[0130] (1) Color value of the reaction solution and polyisocyanate composition: Test according to DIN EN 1557:

[0131] (2) The test method for the outlet conversion rate of the reaction solution is as follows:

[0132] Sampling is diluted with tetrahydrofuran and injected into a GPC instrument with a differential refractive index detector (RID) for detection; GPC integration normalization, conversion rate = 100% - monomer ratio. Peak elution time: PDI monomer 8.6 min, HDI monomer: 8.5 min, IPDI monomer: 8.1 min;

[0133] (3) Viscosity of the polyisocyanate composition: Tested in accordance with DIN EN ISO 3219;

[0134] (4) Mass percentage of each component in the polyisocyanate composition: Detected by gel permeation chromatography (GPC); Instrument: Shimadzu LC-20AD-XR; Method: Dissolve 50 mg of the sample in 1 mL of tetrahydrofuran (THF), Carrier: THF, Detector: Universal detector differential refractive index detector, Flow rate: 0.6 mL / min, Column temperature: 30 °C;

[0135] Among them, urethane A peaks at 8.0 min (number average molecular weight 340), pentamethylene diisocyanate trimer peaks at 7.6 min (number average molecular weight 450), pentamethylene diisocyanate pentamer peaks at 7.1 min (number average molecular weight 767), pentamethylene diisocyanate heptamer peaks at 6.8 min (number average molecular weight 1100), and polymers with more than heptamer show peaks in the gel chromatography with retention times of 5.2 min - 6.8 min;

[0136] Urethane B peaks at 7.8 min (number average molecular weight 374), hexamethylene diisocyanate trimer peaks at 7.5 min (number average molecular weight 535), hexamethylene diisocyanate pentamer peaks at 7.0 min (number average molecular weight 938), hexamethylene diisocyanate heptamer peaks at 6.7 min (number average molecular weight 1280), and polymers with more than heptamer show peaks in the gel chromatography with retention times of 5.2 min - 6.7 min.

[0137] Urethane C peaks at 7.6 min (number average molecular weight 474), isophorone diisocyanate trimer peaks at 7.2 min (number average molecular weight 680), isophorone diisocyanate pentamer peaks at 6.6 min (number average molecular weight 1266), isophorone diisocyanate heptamer peaks at 6.3 min (number average molecular weight 1860), and polymers with more than heptamer show peaks in the gel chromatography with retention times of 5.0 min - 6.3 min.

[0138] (5) Light transmittance of the polyisocyanate composition: Tested by an ultraviolet spectrophotometer (manufacturer METASH), wavelength 660 nm, Cuvette: made of methacrylate, capacity 1.5 mL, optical path 10 mm; Calibration: pure water.

[0139] Table 1

[0140]

[0141] As can be seen from Table 1, the polyisocyanate composition provided by the present invention has the advantages of low viscosity and low color value, and a relatively high content of aliphatic isocyanate trimer.

[0142] As can be seen from Example 5, when the reaction temperature is on the high side, the color value of the reaction solution and the product obtained will be on the high side.

[0143] In Comparative Example 1, a polyisocyanate composition was prepared by a batch reactor. However, the batch reaction is prone to temperature runaway, and the viscosity and color value of the obtained polyisocyanate composition are both high. The microchannel reactor has stable temperature control, good reaction mixing effect, and the obtained polyisocyanate composition has the advantages of low viscosity and low color value.

[0144] As can be seen from Comparative Example 2, when the reaction temperature is low, the proportion of the high polymer will be on the high side, and the viscosity of the obtained product is relatively large.

[0145] As can be seen from Comparative Examples 3-4, when the dosage of the catalyst composite system increases, the content of the aliphatic isocyanate trimer in the prepared polyisocyanate composition is relatively low, which is not conducive to downstream applications; when the dosage of the catalyst composite system decreases, the outlet conversion rate of the reaction solution is relatively low, resulting in a relatively low yield and a relatively high cost of recycling monomers.

[0146] The applicant declares that the present invention uses the above-mentioned examples to illustrate the detailed process equipment and process flow of the present invention. However, the present invention is not limited to the above-mentioned detailed process equipment and process flow, that is, it does not mean that the present invention must rely on the above-mentioned detailed process equipment and process flow 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 the disclosure scope of the present invention.

Claims

1. A polyisocyanate composition, characterized in that, The polyisocyanate composition comprises the following components by mass percentage:

2. The polyisocyanate composition according to claim 1, characterized in that, The aliphatic isocyanate trimer comprises any one or a combination of at least two of pentamethylene diisocyanate trimer, hexamethylene diisocyanate trimer or isophorone diisocyanate trimer; Preferably, the aliphatic isocyanate pentamer comprises any one or a combination of at least two of pentamethylene diisocyanate pentamer, hexamethylene diisocyanate pentamer or isophorone diisocyanate pentamer; Preferably, the aliphatic isocyanurate polymer comprises any one or a combination of at least two of pentamethylene diisocyanate polymer, hexamethylene diisocyanate polymer or isophorone diisocyanate polymer; Preferably, the urethane has the structure shown in Formula I: wherein, R1 and R2 are each independently selected from n-pentylene, n-hexylene or any one of ; "* -" represents the connection site of the group; R3 is selected from any one of C1-C10 straight-chain or branched-chain alkyl groups.

3. The polyisocyanate composition according to claim 1 or 2, characterized in that, The viscosity of the polyisocyanate composition is < 2500 cP, more preferably 1400-2000 cP; Preferably, the color value of the polyisocyanate composition is < 20 HZ; Preferably, the light transmittance of the polyisocyanate composition is 99.5-100%; 4. A method for preparing a polyisocyanate composition according to any one of claims 1-3, characterized in that, The preparation method comprises the following steps: (1) Add the aliphatic isocyanate and the catalyst composite system into a microchannel reactor, and carry out the reaction under the condition of 60-100 °C to obtain a reaction solution; The catalyst composite system comprises a combination of a catalyst and an alcohol solvent; (2) Carry out post-treatment on the reaction solution to obtain the polyisocyanate composition.

5. The preparation method according to claim 4, wherein The aliphatic isocyanate comprises any one or a combination of at least two of pentamethylene diisocyanate, hexamethylene diisocyanate or isophorone diisocyanate; Preferably, the catalyst comprises a quaternary ammonium salt and / or a quaternary ammonium base; Preferably, the quaternary ammonium salt comprises 2-hydroxypropyltrimethylformate ammonium salt and / or 2-hydroxypropyltrimethylisooctanoate ammonium salt; Preferably, the quaternary ammonium base comprises any one or a combination of at least two of tetramethylammonium hydroxide, tetrabutylammonium hydroxide or benzyltrimethylammonium hydroxide; Preferably, the alcohol solvent comprises a primary alcohol; the structure of the primary alcohol is: R-OH; R is selected from any one of C1-C10 straight-chain or branched-chain alkyl groups; Preferably, the primary alcohol is methanol; Preferably, the mass percentage of the catalyst in the catalyst composite system is 10-25%; Preferably, based on the mass of the aliphatic isocyanate being 100%, the mass of the catalyst composite system is 0.1-3%, more preferably 0.6-1.3%; Preferably, the feeding rate of the aliphatic isocyanate is 10-100 mL / min, more preferably 10-50 mL / min; Preferably, the catalyst composite system is added into the microchannel reactor by dropping, and the dropping rate of the catalyst composite system is 5-50 mL / h, more preferably 10-30 mL / h.

6. The preparation method according to claim 4 or 5, characterized in that, A polymerization inhibitor is added during the reaction in step (1); Preferably, the polymerization inhibitor comprises any one or a combination of at least two of phosphoric acid, benzoic acid, benzoyl chloride, bis(2-ethylhexyl) phosphate, dibutyl phosphate or dimethyl phosphate; Preferably, the mass ratio of the polymerization inhibitor to the catalyst is (1-2):

1.

7. The preparation method according to claim 6, characterized in that, The polymerization inhibitor is added into the microchannel reactor by dropping, and the dropping rate of the polymerization inhibitor is calculated according to the following formula: V 阻聚剂 = (1.2 - 2) × V × ρ1 × α / ρ2; wherein, V represents the feeding rate of the catalyst composite system, in mL / h; ρ1 represents the density of the catalyst composite system, with the unit of g / cm 3 ; ρ2 represents the density of the inhibitor, with the unit of g / cm 3 ; α represents the mass percentage of the catalyst in the catalyst composite system.

8. The preparation method according to any one of claims 4-7, characterized in that, The inner diameter of the channels of the microchannel reactor is 0.05-10 mm, more preferably 0.1-0.3 mm; Preferably, the material of the microchannel reactor comprises at least one of Hastelloy, titanium alloy, stainless steel, polytetrafluoroethylene or ceramic; Preferably, the type of the microchannel reactor comprises any one of a scale-type microchannel reactor, a fin-type microchannel reactor, a gourd-type microchannel reactor, a circular microchannel reactor or a triangular microchannel reactor.

9. The preparation method according to any one of claims 4-8, characterized in that, The temperature of the reaction is 60-80 °C; Preferably, the residence time of the aliphatic isocyanate and the catalyst composite system in the microchannel reactor is 1-60 min, preferably 3-20 min; Preferably, the post-treatment comprises thin-film evaporation and / or molecular distillation.

10. Use of a polyisocyanate composition according to any one of claims 1-3 in a polyurethane coating.

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