A polyisocyanate composition based on isophorone diisocyanate

Abstract

The present invention provides an isophorone diisocyanate (IPDI)-based polyisocyanate composition having a molar ratio of free aliphatic isocyanate groups to free alicyclic isocyanate groups of 0.26 / 0.74 to 0.4 / 0.6, which can improve the reactivity of the IPDI-based polyisocyanate composition with hydroxyl groups and water vapor.

Description

Technical Field

[0001] This invention belongs to the technical field of polyisocyanates, specifically relating to a polyisocyanate composition based on isophorone diisocyanate. Background Technology

[0002] Polyisocyanate compositions prepared by polymerization of isophorone diisocyanate monomer (IPDI) have been widely used in the polyurethane coatings or adhesives industry. Through the self-polymerization of diisocyanate monomer, the harmfulness of volatile isocyanate monomers to human health can be effectively reduced.

[0003] The technology of modifying isophorone diisocyanate under the action of a catalyst is well known in the field. For example, a trimerization reaction is carried out, and after the expected conversion rate is achieved, the remaining monomers are removed by vacuum distillation or thin-film evaporation to obtain polyisocyanate composition products based on IPDI. For reference, see patents US4288586, US6093817, CN107827832, etc.

[0004] However, in actual use, it has been found that the reactivity of polyisocyanate compositions based on IPDI is not easy to control. Sometimes, the reaction with hydroxyl resins in downstream applications is too slow, affecting the drying speed of the paint film. At other times, the high reactivity may cause water vapor to bind easily, resulting in a "skin" phenomenon on the solution surface. Summary of the Invention

[0005] In view of this, in order to improve the reactivity of IPDI-based polyisocyanate compositions with hydroxyl groups and water vapor, the present invention provides a polyisocyanate composition based on isophorone diisocyanate. In downstream applications, on the one hand, it can improve the reactivity with hydroxyl resins and accelerate the drying speed of the paint film; on the other hand, it can simultaneously reduce the reactivity with water vapor, avoid the formation of a "skin" on the solution surface, and give it good storage stability.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] This invention provides a polyisocyanate composition based on isophorone diisocyanate (IPDI), wherein the molar ratio of free aliphatic isocyanate groups to free alicyclic isocyanate groups is 0.26 / 0.74 to 0.4 / 0.6, for example 0.27 / 0.73, 0.30 / 0.70, 0.32 / 0.68, 0.34 / 0.66, 0.36 / 0.64, 0.38 / 0.62, preferably 0.28 / 0.72 to 0.35 / 0.65.

[0008] The structure of isophorone diisocyanate monomer (IPDI) is shown in Formula 1:

[0009]

[0010] As can be seen from Formula 1, IPDI has two NCO groups at different positions, represented as an alicyclic isocyanate group (labeled a) and an aliphatic isocyanate group (labeled b). Due to the difference in spatial position and connecting groups, the two NCO groups have different activities. In the composition of this invention, the free aliphatic isocyanate group and the free alicyclic isocyanate group refer to the remaining NCO groups of the IPDI molecule that did not participate in the cyclic polymerization reaction during the polymerization process. In other words, during the polymerization reaction, generally one of the two NCO groups of the IPDI molecule participates in the polymerization reaction, leaving one free NCO group, such as the remaining a group or b.

[0011] During the research process, this invention discovered that controlling the ratio of free aliphatic isocyanate groups to free alicyclic isocyanate groups in IPDI-based polyisocyanate compositions affects their reactivity with hydroxyl resins and moisture in downstream applications. Limiting the molar ratio of free aliphatic isocyanate groups to free alicyclic isocyanate groups to 0.26 / 0.74–0.4 / 0.6, especially within the range of 0.28 / 0.72–0.35 / 0.65, can effectively improve the reactivity of the polyisocyanate composition with hydroxyl groups and moisture, keeping both within a suitable range and balancing their reactivity. Increasing this ratio often negatively impacts the storage stability of the composition, such as causing surface crusting in solution, while decreasing this ratio often negatively impacts its reactivity with hydroxyl resins, such as slowing down the drying process.

[0012] For polyisocyanate compositions based on isophorone diisocyanate (IPDI), the method for controlling the ratio of free aliphatic isocyanate groups to free alicyclic isocyanate groups is often not singular. Those skilled in the art can use any feasible method known in the prior art, such as controlling the reaction temperature, the type of catalyst, or the ratio of cis and trans isocyanates in the isophorone diisocyanate monomer raw material. It is preferred to control the ratio of cis and trans isocyanates in the isophorone diisocyanate monomer raw material.

[0013] The IPDI monomer contains two structures: the cis form (Equation 2) and the trans form (Equation 3), as follows:

[0014]

[0015] In some specific embodiments, the polyisocyanate composition based on isophorone diisocyanate of the present invention, with the total mass of the polyisocyanate composition being 100%, wherein the total mass ratio of mononuclear and binuclear is 78-90%, for example 80%, 82%, 84%, 86%, 88%, preferably 82-86%.

[0016] The mononuclear form of a polyisocyanate specifically refers to the trimer structure shown in Formula 4 obtained after the polymerization of isocyanate monomers. Further, the mononuclear form can be polymerized with two more monomers to obtain a pentamer structure shown in Formula 5, i.e., a binuclear form. Similarly, the binuclear form with the structure shown in Formula 5 can be further polymerized to obtain trinuclear, tetranuclear, pentanuclear, and more polynuclear forms. For example, the mononuclear form with the structure shown in Formula 4 can be further polymerized to obtain the binuclear form with the structure shown in Formula 5.

[0017]

[0018] The present invention discovered in experiments that the reactivity of polyisocyanate compositions based on IPDI is also related to the content of mononuclear and binuclear molecules. In the polyisocyanate compositions of the present invention, the higher the content of mononuclear and binuclear molecules, the lower the viscosity of the polyisocyanate composition, but the lower its functionality and the lower the reaction conversion rate; while the lower the content of mononuclear and binuclear molecules, although the conversion rate and functionality are improved, the viscosity increases and the NCO content decreases.

[0019] There are various methods for controlling the content of mononuclear and binuclear bodies in polyisocyanate compositions based on isophorone diisocyanate (IPDI). Those skilled in the art can use any feasible method known in the prior art. This invention does not have any particular requirements, such as controlling the NCO value at the end of the reaction process, heat treatment of the reaction solution, control of the separation temperature, and heat treatment of the polyisocyanate composition.

[0020] It should be noted that the content of mononuclear and binuclear molecules in the polyisocyanate composition can be tested using gel permeation chromatography (GPC) as described in the examples below.

[0021] The polyisocyanate composition based on isophorone diisocyanate described in this invention is in solid or solution form after being dissolved in a solvent;

[0022] Since the polyisocyanate composition described in this invention is in a solid state at room temperature, generally referring to 25°C, in some specific embodiments, the polyisocyanate composition based on isophorone diisocyanate described in this invention can also be dissolved in a solvent to obtain a polyisocyanate composition solution, which is in the state of a solution after being dissolved in a solvent.

[0023] In the polyisocyanate composition solution of the present invention, the solvent is selected from any one or a combination of at least two of butyl acetate, ethyl acetate, solvent oil, toluene, xylene, propylene glycol methyl ether acetate, diheptanone, etc.

[0024] Preferably, the solvent accounts for 28-32% by mass, for example 29%, 30%, 31%, and more preferably 30%, based on the total mass of the polyisocyanate composition solution being 100%. If the solvent content in the composition solution is too high, it will reduce the economic benefits of downstream applications, while if the solvent content is too low, it will make the solution viscosity too high, which is also not lower than that used downstream.

[0025] In some specific embodiments, the isocyanate composition based on isophorone diisocyanate of the present invention, based on 100% of the total mass of the polyisocyanate composition, contains 15-19% isocyanate (-NCO) groups, for example 15.5%, 16.0%, 16.5%, 17.0%, 17.5%, 18.0%, 18.5%, preferably 15.7-18.5%, and more preferably 17%. On the one hand, the NCO group content in the composition should not be too low, as this is not conducive to the structural cross-linking of the paint film; on the other hand, the NCO content should not be too high, as this usually reduces the hardness of the paint film.

[0026] Preferably, the polyisocyanate composition solution corresponding to the solution state after dissolving it in a solvent, based on the total mass of the polyisocyanate composition solution of 100%, contains 11-13% NCO groups, for example 11.3%, 11.6%, 11.9%, 12.2%, 12.5%, 12.8%, preferably 12%.

[0027] In some specific embodiments, the isophorone diisocyanate-based polyisocyanate composition of the present invention contains isophorone diisocyanate monomer content of less than 0.5 wt%, for example 0.01 wt%, 0.05 wt%, 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, preferably less than 0.35 wt%, more preferably less than 0.1 wt%. The reduced content of IPDI monomer is beneficial to downstream construction safety.

[0028] The preparation method of the polyisocyanate composition based on isophorone diisocyanate of the present invention is not limited, as long as the composition of the polyisocyanate composition meets the aforementioned requirements of the present invention. According to methods disclosed in the prior art, for example, it can be prepared by the following method:

[0029] In the presence of a polymerization catalyst, isophorone diisocyanate undergoes a polymerization reaction, which is terminated when the NCO group content in the system reaches 20-30%, for example 24%, 25%, 26%, or 27%, to obtain a polyisocyanate composition based on isophorone diisocyanate.

[0030] The basic method for the polymerization of isocyanates is known in the prior art. In the specific polymerization process, isophorone diisocyanate can be added to a round-bottom flask equipped with a reflux condenser, stirrer, thermometer and nitrogen inlet. Then the system is heated to the predetermined reaction temperature range (e.g. 50-110°C, such as 70°C or 90°C) and then a catalyst solution is added dropwise. As is well known to those skilled in the art, the specific operating parameters and operating sequence of the polymerization reaction are common knowledge in the field and will not be described in detail here.

[0031] In some specific embodiments, the molar ratio of cis to trans in the isophorone diisocyanate monomer raw material is 88 / 12 to 60 / 40, for example 87 / 13, 84 / 16, 80 / 20, 78 / 22, 75 / 24, 72 / 29, preferably 85 / 15 to 70 / 30.

[0032] In some specific embodiments, the amount of catalyst used is 0.001 to 0.1% of the mass of isophorone diisocyanate, for example 0.005%, 0.01%, 0.02%, 0.04%, 0.06%, 0.08%, preferably 0.01 to 0.03%.

[0033] The catalysts used in this invention include: (1) hydroxides of tetraalkylammonium (e.g., tetramethylammonium hydroxide, tetraethylammonium hydroxide, benzyltrimethylammonium hydroxide, etc.), or organic acid salts of tetraalkylammonium (e.g., tetramethylammonium acetate, tetraethylammonium butyrate, etc.); (2) hydroxides of hydroxyalkylammonium (e.g., trimethylhydroxypropylammonium, trimethylhydroxyethylammonium, triethylhydroxypropylammonium, etc.) or their organic acid salts (e.g., acetic acid, butyric acid, isooctanoic acid, etc.); (3) metal salts (e.g., tin, zinc, etc.) of alkylcarboxylic acids (e.g., acetic acid, decanoic acid, octanoic acid, etc.); preferably one of (1) or (2).

[0034] In some specific embodiments, the catalyst used in this invention is dissolved in an organic solvent to prepare a catalyst solution, and then added to the system to catalyze the polymerization reaction.

[0035] Specifically, the catalyst concentration in the catalyst solution is 1-40%, for example 5%, 10%, 15%, 20%, 25%, 30%, 35%, preferably 10-30%.

[0036] Specifically, the organic solvent is selected from alcohol solvents, preferably any one or a combination of at least two of monools and diols. In this invention, the monool may be selected from any one or a combination of at least two of 1-propanol, 2-propanol, n-butanol, isobutanol, sec-butanol, tert-butanol, n-octanol, isooctanol, heptanol, n-butanol, hexanol, heptanol, or isooctanol; the diol may be selected from any one or a combination of at least two of diethylene glycol, 1,3-butanediol, 1,6-hexanediol, 1,4-butanediol, 2-ethyl-1,6-hexanediol, etc.

[0037] In some specific embodiments, when the above polymerization reaction proceeds to an NCO value of 23-28% in the system, such as 24%, 25%, 26%, or 27%, a terminator can be used to terminate the reaction. Specifically, the molar ratio of the terminator to the catalyst is 1-1.1, such as 1.02, 1.04, 1.06, or 1.08, preferably 1.

[0038] The terminator is selected from any one or a combination of at least two of phosphate esters or benzenesulfonic acid terminators, such as dibutyl phosphate, diisooctyl phosphate, or p-toluenesulfonic acid.

[0039] In some other embodiments, the polymerization reaction described above can also be terminated by heating and holding for a period of time. In specific implementation, the system can be heated to 120-130°C (e.g., 122°C, 124°C, 126°C, 128°C) and held for 30-60 minutes (e.g., 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes).

[0040] After the polymerization reaction is completed, in some preferred embodiments, unreacted isophorone diisocyanate monomers can be removed from the polymerization system using thin-film evaporation. During the removal process, increasing the temperature further facilitates a reduction in the proportion of mononuclear and binuclear monomers. In some specific embodiments, a thin-film evaporator can be used to remove unreacted isophorone diisocyanate monomers from the reaction system under conditions of 170–200°C (e.g., 170°C, 180°C, 190°C) and 10–200 Pa (e.g., 50 Pa, 100 Pa, 150 Pa). In some other preferred embodiments, after removing the unreacted isophorone diisocyanate monomers, the content of mononuclear and binuclear monomers in the composition can be controlled by increasing the residence time. In specific implementations, after removing the unreacted monomers, the composition can continue to be held at the above-mentioned temperature for a period of time, which can be 10–30 min, for example, 10 min, 20 min, or 30 min.

[0041] The IPDI-based polyisocyanate composition of the present invention exhibits good reactivity with hydroxyl resins, enabling the drying speed of the paint film to be controlled within a suitable range, and the hardness of the resulting coating is also correspondingly improved.

[0042] The IPDI-based polyisocyanate composition of the present invention has low reactivity with water vapor and good storage stability. When left to stand for 5 minutes at room temperature (25°C) and 70% humidity, there is basically no skin formation.

[0043] The IPDI-based polyisocyanate composition of the present invention can simultaneously improve the reactivity with hydroxyl groups and water vapor, and can be used in automotive refinish paints, automotive original paints, rail transit coatings, hot melt adhesives, solar backsheet adhesives and other fields.

[0044] Compared with the prior art, the beneficial effects of the technical solution of the present invention are as follows:

[0045] This invention provides a polyisocyanate composition based on IPDI. By controlling the ratio of alicyclic isocyanate groups to fatty isocyanate groups in the composition to 0.26 / 0.74 to 0.4 / 0.6, preferably 0.28 / 0.72 to 0.35 / 0.65, the reactivity of the polyisocyanate composition with hydroxyl resins and water vapor can be significantly improved. Furthermore, by limiting the mass ratio of mononuclear to binuclear groups to 78% to 87%, it is more conducive to downstream construction operations and has better economic benefits.

[0046] The polyisocyanate composition based on IPDI described in this invention can simultaneously improve the reactivity with hydroxyl groups and water vapor. It can increase the reactivity with hydroxyl resins while reducing the reactivity with water vapor, so that both reactivity are within the optimal range and achieve an effective balance. This solves the problem in downstream applications where the drying speed of the paint film is affected by the slow reaction with hydroxyl resins when the activity is too low, while the "skinning" phenomenon on the solution surface is caused by the easy binding of water vapor when the activity is too high. Attached Figure Description

[0047] Figure 1 Here is an example of a typical GPC spectrum for an IPDI-based polyisocyanate composition. Detailed Implementation

[0048] To better understand the present invention, the following embodiments further illustrate the content of the present invention.

[0049] The main raw material sources used in the following examples are as follows; unless otherwise specified, all other raw materials are common commercially available:

[0050] The main raw material sources for each of the following embodiments are as follows; unless otherwise specified, all other raw materials are common commercially available:

[0051] Isophorone diisocyanate (IPDI): Wanhua Chemical, >99.5%, WANNATE IPDI;

[0052] n-Hexyl alcohol: Sigma-Aldrich, 98%;

[0053] Isooctyl alcohol: Sigma-Aldrich, 98%;

[0054] n-Butanol: Sigma-Aldrich, 99%;

[0055] 1,3-Butanediol: Sigma-Aldrich, 99%;

[0056] Trimethylhydroxypropyl isooctanoate ammonium: Sigma-Aldrich, 95%;

[0057] Benzyltrimethylammonium hydroxide: Sigma-Aldrich, 95%;

[0058] Tetrabutylammonium hydroxide: Sigma-Aldrich, 95%;

[0059] Tetrabutylammonium acetate: Sigma-Aldrich, 96%

[0060] Dibutyl phosphate, Sigma-Aldrich, 97%;

[0061] Diisooctyl phosphate, Sigma-Aldrich, 96%;

[0062] p-Toluenesulfonic acid, Sigma-Aldrich, 95%;

[0063] Butyl acetate: National Pharmaceutical Reagent, 99%

[0064] Solvent oil S100: Huafeng Spandex industrial product.

[0065] The following methods were used to test the following embodiments:

[0066] (1) Test method for monomer content in polyisocyanate composition: GB / T 18446-2009.

[0067] (2) Determination of NCO group content: The NCO group content based on the total mass of the sample is obtained by neutralizing the isocyanate groups in the sample with excess 2 mol / L di-n-butylamine and then back-titrifying with 1 mol / L hydrochloric acid. The calculation formula is as follows:

[0068]

[0069] Where: V—volume of hydrochloric acid standard solution used in titration of the sample, ml;

[0070] V0—The volume of hydrochloric acid standard solution used in the blank titration, in ml;

[0071] c—The actual concentration of the hydrochloric acid standard solution, in mol / L;

[0072] 0.04202 — The mass of isocyanate ions, expressed in grams, equivalent to 1.00 ml of standard hydrochloric acid solution [c(HCl) = 1.000 mol / L];

[0073] m—total sample mass, g.

[0074] (3) Methods for analyzing the content of mononuclear and binuclear molecules in polyisocyanate compositions:

[0075] The gel permeation chromatography (GPC) method was used for determination: approximately 0.25 g of sample was weighed, dissolved in dichloromethane to prepare a 2.5 ml solution, and then the sample was determined under the following conditions:

[0076] ① Analytical apparatus: Alliance (Waters);

[0077] ② Pump: Allianz 2695 (Waters);

[0078] ③ Detector: Type 2414 differential refraction detector (Waters);

[0079] ④ Eluent: Tetrahydrofuran;

[0080] ⑤ Separation column: Plgel guard + Plgel 51-1m Mixed-C × 3 (50×7.5mm, 300×7.5mm), model: PLl 110-6500;

[0081] ⑥ Measurement temperature: 40℃;

[0082] ⑦ Flow rate: 1 mL / min;

[0083] ⑧ Sample injection volume: 20 μl;

[0084] ⑨ Analysis device: Waters data processing device:

[0085] Typical GPC spectra obtained by testing IPDI-based polyisocyanate compositions using the above method are as follows: Figure 1 The peak areas are shown in Table 1 below:

[0086] Table 1

[0087] category Multinucleoid Quad-core Tri-core Binary nucleus Mononuclear body monomer data / % 2.75 3.84 9.16 22.77 61.16 0.32

[0088] The proportion of mononuclear and binuclear molecules in the polyisocyanate composition was calculated using the area ratio in the spectrum.

[0089] (4) Test method for the ratio of alicyclic isocyanate to fatty isocyanate in polyisocyanate compositions (labeled as ratio A):

[0090] 13 13C NMR spectroscopy: Instrument: Bruker Biospin Avance 600; Observation (frequency): 13C (150MHz); Solvent (concentration): CDCl3 (60 mass / volume%); Total number of times: 10,000;

[0091] Decoupled protons by integral 13 C NMR spectroscopy calculations and calculations based on the sum of the present alicyclic and fatty isocyanates respectively; each structural element has the following chemical shifts (in ppm): free alicyclic isocyanate: 122.8; free fatty isocyanate: 121.9.

[0092] (5) Drying performance test and mechanical property test methods

[0093] Procedure: Mix the polyisocyanate composition solution of the sample to be tested with curing agent HT100 (Wanhua Chemical) at a mass ratio of 2:1, then dilute with xylene to a solid content of 40wt%, and then mix with Tongde ACR6780 resin at a ratio of NCO:OH = 1.2:1 to obtain the initial paint. After mixing evenly, apply the paint to a glass plate and perform relevant tests.

[0094] Finger-touch dryness test method: The time it takes for the paint to be applied to a glass plate and for the surface to feel dry to the touch without any paint sticking to the touch, in minutes;

[0095] According to the above test method of the present invention, the effect is better when the drying time is within 16 minutes, but less than 20 minutes is still within the acceptable range. If the drying time continues to increase and the drying speed is too slow, it indicates that the sample has too low reactivity with hydroxyl groups.

[0096] Pendulum hardness test method: Test standard GB / T 1730-93, using a König pendulum, model: German Erichsen 299 / 300, the standard plate is the instrument's own test plate, used for comparison. Place the freshly prepared sample at room temperature for 15-20 minutes, then bake at 70℃ for 60 minutes before testing. Test result = number of pendulum cycles for sample / number of pendulum cycles for standard plate;

[0097] According to the above test method of the present invention, the effect is better if the test result is higher than 0.74, but it is still within the ideal range if it is not lower than 0.7. If it is lower than this value, it indicates that the crosslinking density between the sample and the resin is too low and the hardness of the paint film is insufficient.

[0098] (6) Evaluation method for surface phenomena of the composition solution (used to evaluate reactivity with water vapor):

[0099] Add 150g of the polyisocyanate composition solution to the sample in a 250ml disposable plastic cup. Place it at 25℃ and 70% humidity for 5 minutes. Then, gently slide a glass rod around the surface and lift the glass rod about 4-5cm from the surface. According to the state and stability of the film, it is divided into four categories: none, mild, moderate, and severe. The specific judgment criteria are as follows:

[0100] None: No film-like substance adhered to the glass rod;

[0101] Mild: A film-like substance adheres to the glass rod, but it does not exhibit stringy characteristics;

[0102] Moderate: A film-like substance adheres to the glass rod, exhibiting a stringy phenomenon, which easily breaks into droplets or ribbons.

[0103] Heavy: A film-like substance is clearly visible on the surface of the solution, and a film-like substance adheres to the glass rod, which is stable and easy to draw into threads without breaking.

[0104] Based on the above judgment criteria, in actual application, no crusting is optimal, but mild crusting is still within the acceptable range. If moderate or severe crusting occurs, it indicates that the reaction rate with water vapor is too fast and the reactivity is too high.

[0105] (7) Test method for solid content:

[0106] Weigh an accurate amount of the composition solution sample (approximately 0.5 g) and place it in an aluminum foil dish (weighing accurately). Place the dish in a 120°C oven and let it stand for 2 hours. Remove it, cool it, and weigh it.

[0107] Solid content = (weight after drying - weight of aluminum foil dish) / sample weight * 100%.

[0108] Example 1

[0109] Preparation of catalyst solution: Tetrabutylammonium hydroxide was dissolved in n-butanol to prepare a 20wt% solution.

[0110] 1000g of IPDI (cis / trans molar ratio 76 / 24) was placed in a round-bottom flask equipped with a reflux condenser, stirrer, thermometer, and nitrogen inlet. The reaction system was heated to 70°C, and then the catalyst solution prepared above (catalyst amount was 0.015% of the mass of IPDI) was added dropwise to the reaction system with stirring. The polymerization reaction was carried out at a temperature between 70 and 80°C. When the NCO content of the reaction solution was 28%, dibutyl phosphate with an equimolar amount of catalyst was added to terminate the reaction, and the polymerization reaction solution was obtained.

[0111] Unreacted isophorone diisocyanate monomer was removed from the polymerization reaction solution using a thin-film evaporator at a temperature of 180°C and an absolute pressure of 50 Pa, reducing its content to 0.34 wt%. The monomer was then dissolved in butyl acetate to obtain a solution product with a solid content of 70 wt%, yielding a polyisocyanate composition solution 1 with a viscosity of 600 cP at 25°C.

[0112] Example 2

[0113] Preparation of catalyst solution: Trimethylhydroxypropyl isooctanoate ammonium was dissolved in isooctyl alcohol to prepare a 30wt% solution.

[0114] 1000g of IPDI (cis / trans molar ratio 78 / 22) was placed in a round-bottom flask equipped with a reflux condenser, stirrer, thermometer, and nitrogen inlet. The reaction system was heated to 80°C, and then the catalyst solution prepared above (catalyst amount was 0.016% of IPDI mass) was added dropwise to the reaction system with stirring. The polymerization reaction was carried out at a temperature between 80 and 90°C. When the NCO content of the reaction solution was 25%, diisooctyl phosphate was added in an equal molar amount to the catalyst to terminate the reaction, and the polymerization reaction solution was obtained.

[0115] Unreacted isophorone diisocyanate monomer was removed from the polymerization reaction solution using a thin-film evaporator at a temperature of 190°C and an absolute pressure of 50 Pa, reducing its content to 0.32 wt%. The monomer was then dissolved in butyl acetate to obtain a solution product with a solid content of 70 wt%, yielding a polyisocyanate composition solution 2 with a viscosity of 630 cP at 25°C.

[0116] Example 3

[0117] Preparation of catalyst solution: Benzyltrimethylammonium hydroxide was dissolved in hexanol to prepare a 1 wt% solution.

[0118] 1000g of IPDI (cis / trans molar ratio 80 / 20) was placed in a round-bottom flask equipped with a reflux condenser, stirrer, thermometer, and nitrogen inlet. The reaction system was heated to 60°C, and then the catalyst solution prepared above (catalyst amount was 0.015% of the mass of IPDI) was added dropwise to the reaction system with stirring. The polymerization reaction was carried out at a temperature between 60 and 70°C. When the NCO content of the reaction solution was 26%, diisooctyl phosphate with a molar ratio of 1.1 to the catalyst was added to terminate the reaction, and the polymerization reaction solution was obtained.

[0119] Unreacted isophorone diisocyanate monomer was removed from the polymerization reaction solution using a thin-film evaporator at a temperature of 180°C and an absolute pressure of 100 Pa, reducing its content to 0.33 wt%. The monomer was then dissolved in butyl acetate to obtain a solution product with a solid content of 70 wt%, yielding a polyisocyanate composition solution 3 with a viscosity of 610 cP at 25°C.

[0120] Example 4

[0121] Preparation of catalyst solution: Tetrabutylammonium acetate was dissolved in 1,3-butanediol to prepare a 40 wt% solution.

[0122] 1000g of IPDI (cis / trans molar ratio 81 / 19) was placed in a round-bottom flask equipped with a reflux condenser, stirrer, thermometer, and nitrogen inlet. The reaction system was heated to 70°C, and then the catalyst solution prepared above (catalyst amount was 0.0155% of IPDI mass) was added dropwise to the reaction system with stirring. The polymerization reaction was carried out at a temperature between 70 and 80°C. When the NCO content of the reaction solution was 23%, p-toluenesulfonic acid with an equimolar amount of catalyst was added to terminate the reaction, and the polymerization reaction solution was obtained.

[0123] Unreacted isophorone diisocyanate monomers in the polymerization reaction solution were evaporated and removed using a thin-film evaporator at a temperature of 200°C and an absolute pressure of 100 Pa, reducing their content to 0.3 wt%. The solution was then dissolved in solvent oil S100 to obtain a solution product with a solid content of 70 wt%, yielding a polyisocyanate composition solution 4 with a viscosity of 2100 cP at 25°C.

[0124] Example 5

[0125] Preparation of catalyst solution: Same as in Example 2

[0126] 1000g of IPDI (cis / trans molar ratio 80 / 20) was placed in a round-bottom flask equipped with a reflux condenser, stirrer, thermometer, and nitrogen inlet. The reaction system was heated to 90°C, and then the catalyst solution prepared above (catalyst amount was 0.016% of IPDI mass) was added dropwise to the reaction system with stirring. The polymerization reaction was carried out at a temperature between 100 and 110°C. When the NCO content of the reaction solution system was 26%, the system was raised to 130°C and held for 30 minutes to obtain the polymerization reaction solution.

[0127] Unreacted isophorone diisocyanate monomer was removed from the polymerization reaction solution by evaporation using a thin-film evaporator at a temperature of 190°C and an absolute pressure of 50 Pa. The solution was held for 30 min to reduce its content to 0.3 wt%. The solution was then dissolved in propylene glycol methyl ether acetate / xylene (mass ratio 1:1) to obtain a solution product with a solid content of 70 wt%, yielding a polyisocyanate composition solution 5 with a viscosity of 1900 cP at 25°C.

[0128] Example 6

[0129] Preparation of catalyst solution: Same as in Example 1

[0130] 1000g of IPDI (cis / trans molar ratio 76 / 24) was placed in a round-bottom flask equipped with a reflux condenser, stirrer, thermometer, and nitrogen inlet. The reaction system was heated to 70°C, and then the catalyst solution prepared above (catalyst amount was 0.016% of the mass of IPDI) was added dropwise to the reaction system with stirring. The polymerization reaction was carried out at a temperature between 70 and 80°C. When the NCO content of the reaction solution was 23%, dibutyl phosphate with an equimolar amount of tetrabutylammonium difluoride was added to terminate the reaction, and the polymerization reaction solution was obtained.

[0131] Unreacted isophorone diisocyanate monomers were removed from the polymerization reaction solution using a thin-film evaporator at a temperature of 190°C and an absolute pressure of 50 Pa, reducing its content to 0.34 wt%. The solution was then dissolved in butyl acetate to obtain a solution product with a solid content of 70 wt%, yielding polyisocyanate composition 6 with a viscosity of 700 cP at 25°C.

[0132] Example 7

[0133] Preparation of catalyst solution: Same as in Example 1

[0134] 1000g of IPDI (cis / trans molar ratio 76 / 24) was placed in a round-bottom flask equipped with a reflux condenser, stirrer, thermometer, and nitrogen inlet. The reaction system was heated to 70°C, and then the catalyst solution prepared above (catalyst amount was 0.014% of the mass of IPDI) was added dropwise to the reaction system with stirring. The polymerization reaction was carried out at a temperature between 70 and 80°C. When the NCO content of the reaction solution was 28.5%, dibutyl phosphate with an equimolar amount of tetrabutylammonium difluoride was added to terminate the reaction, and a polymerization reaction solution was obtained. Unreacted isophorone diisocyanate monomer was evaporated and removed from the polymerization reaction solution using a thin-film evaporator at a temperature of 170°C and an absolute pressure of 50 Pa, so that its content was 0.34 wt%. The solution product was dissolved in butyl acetate to obtain a solution product with a solid content of 70 wt%, resulting in a polyisocyanate composition 7 with a viscosity of 550 cP at 25°C.

[0135] Example 8

[0136] Preparation of catalyst solution: Same as in Example 1

[0137] 1000g of IPDI (cis / trans molar ratio 85 / 15) was placed in a round-bottom flask equipped with a reflux condenser, stirrer, thermometer, and nitrogen inlet. The reaction system was heated to 70°C, and then the catalyst solution prepared above (catalyst amount was 0.014% of the mass of IPDI) was added dropwise to the reaction system with stirring. The polymerization reaction was carried out at a temperature between 70 and 80°C. When the NCO content of the reaction solution was 29%, dibutyl phosphate with an equimolar amount of tetrabutylammonium difluoride was added to terminate the reaction, and a polymerization reaction solution was obtained. Unreacted isophorone diisocyanate monomer was evaporated and removed from the polymerization reaction solution using a thin-film evaporator at a temperature of 180°C and an absolute pressure of 50 Pa, so that its content was 0.34 wt%. The solution product was dissolved in butyl acetate to obtain a solution product with a solid content of 70 wt%, resulting in polyisocyanate composition 8 with a viscosity of 600 cP at 25°C.

[0138] Example 9

[0139] Preparation of catalyst solution: Same as in Example 1

[0140] 1000g of IPDI (cis / trans molar ratio 85 / 15) was placed in a round-bottom flask equipped with a reflux condenser, stirrer, thermometer, and nitrogen inlet. The reaction system was heated to 70°C, and then the catalyst solution prepared above (catalyst amount was 0.017% of IPDI mass) was added dropwise to the reaction system with stirring. The polymerization reaction was carried out at a temperature between 70 and 80°C. When the NCO content of the reaction solution was 23%, dibutyl phosphate with an equimolar amount of tetrabutylammonium difluoride was added to terminate the reaction, resulting in a polymerization reaction solution. Unreacted isophorone diisocyanate monomer was evaporated and removed from the polymerization reaction solution using a thin-film evaporator at a temperature of 190°C and an absolute pressure of 50 Pa, reducing its content to 0.34 wt%. The solution was then dissolved in butyl acetate to obtain a solution product with a solid content of 70 wt%, yielding polyisocyanate composition 9 with a viscosity of 690 cP at 25°C.

[0141] Comparative Example 1

[0142] Preparation of catalyst solution: Same as in Example 1

[0143] 1000g of IPDI (cis / trans molar ratio 66 / 34) was placed in a round-bottom flask equipped with a reflux condenser, stirrer, thermometer, and nitrogen inlet. The reaction system was heated to 70°C, and then the catalyst solution prepared above (0.015% of the mass of IPDI) was added dropwise to the reaction system with stirring. The polymerization reaction was carried out at a temperature between 100 and 110°C. When the NCO content of the reaction solution was 28%, dibutyl phosphate with an equimolar amount of tetrabutylammonium difluoride was added to terminate the reaction, and the polymerization reaction solution was obtained.

[0144] Unreacted isophorone diisocyanate monomers in the polymerization reaction solution were evaporated and removed using a thin-film evaporator at a temperature of 180°C and an absolute pressure of 50 Pa, reducing its content to 0.34 wt%. The resulting solution was dissolved in butyl acetate to obtain a product with a solid content of 70%, yielding a polyisocyanate composition 1-1 with a viscosity of 600 cP at 25°C.

[0145] Comparative Example 2

[0146] Preparation of catalyst solution: Same as in Example 1

[0147] 1000g of IPDI (cis / trans molar ratio 90 / 10) was placed in a round-bottom flask equipped with a reflux condenser, stirrer, thermometer, and nitrogen inlet. The reaction system was heated to 70°C, and then the catalyst solution prepared above (catalyst amount was 0.015% of the mass of IPDI) was added dropwise to the reaction system with stirring. The polymerization reaction was carried out at a temperature between 70 and 80°C. When the NCO content of the reaction solution was 28%, dibutyl phosphate with an equimolar amount of tetrabutylammonium difluoride was added to terminate the reaction, and the polymerization reaction solution was obtained.

[0148] Unreacted isophorone diisocyanate monomers in the polymerization reaction solution were evaporated and removed using a thin-film evaporator at a temperature of 180°C and an absolute pressure of 50 Pa, reducing its content to 0.34 wt%. The solution was then dissolved in butyl acetate to obtain a solution product with a solid content of 70%, yielding polyisocyanate composition 1-2 with a viscosity of 590 cP at 25°C.

[0149] Comparative Example 3

[0150] Preparation of catalyst solution: Same as in Example 2

[0151] 1000g of IPDI (cis / trans molar ratio 66 / 34) was placed in a round-bottom flask equipped with a reflux condenser, stirrer, thermometer, and nitrogen inlet. The reaction system was heated to 80°C, and then the catalyst solution prepared above (catalyst amount was 0.016% of IPDI mass) was added dropwise to the reaction system with stirring. The polymerization reaction was carried out at a temperature between 40 and 50°C. When the NCO content of the reaction solution was 25%, dibutyl phosphate with an equimolar amount of catalyst was added to terminate the reaction, and the polymerization reaction solution was obtained.

[0152] Unreacted isophorone diisocyanate monomers in the polymerization reaction solution were evaporated and removed using a thin-film evaporator at a temperature of 190°C and a residence time of 80 min, and an absolute pressure of 50 Pa, so that their content was 0.32 wt%. The solution product was then dissolved in butyl acetate to obtain a solution product with a solid content of 70%, resulting in polyisocyanate composition 1-3 with a viscosity of 640 cP at 25°C.

[0153] The composition, storage stability (i.e., "skinning"), drying and mechanical properties of the polyisocyanate compositions prepared in the above examples and comparative examples were tested, and the results are shown in Tables 2 and 3.

[0154] Table 2. Composition and Storage Stability Test Results

[0155]

[0156] Table 3 Results of Drying Performance and Mechanical Property Tests

[0157] Polyisocyanate composition solution 1 16 0.77 Polyisocyanate composition solution 2 13 0.76 Polyisocyanate composition solution 3 14 0.75 Polyisocyanate composition solution 4 12 0.74 Polyisocyanate composition solution 5 17 0.75 Polyisocyanate composition solution 6 14 0.7 Polyisocyanate composition solution 7 19 0.75 Polyisocyanate composition solution 8 20 0.74 Polyisocyanate composition solution 9 17 0.7 Polyisocyanate composition solution 1-1 12 0.8 Polyisocyanate composition solution 1-2 24 0.69 Polyisocyanate composition solution 1-3 10 0.82

[0158] Although the invention has been described in detail above for illustrative purposes, such description is merely for illustrative purposes, and those skilled in the art can make changes to it without departing from the spirit and scope of the invention, which is defined by the claims.

Claims

1. A polyisocyanate composition based on isophorone diisocyanate, characterized in that, The molar ratio of free aliphatic isocyanate groups to free alicyclic isocyanate groups is 0.26 / 0.74 to 0.4 / 0.

6. Based on the total mass of the polyisocyanate composition as 100%, the total mass percentage of mononuclear and binuclear forms is 78-90%.

2. The polyisocyanate composition according to claim 1, characterized in that, The molar ratio of free aliphatic isocyanate groups to free alicyclic isocyanate groups is 0.28 / 0.72 to 0.35 / 0.

65.

3. The polyisocyanate composition according to claim 1, characterized in that, Based on the total mass of the polyisocyanate composition as 100%, the total mass percentage of mononuclear and binuclear forms is 82-86%.

4. The polyisocyanate composition according to claim 1, characterized in that, It is either a solid at room temperature or a solution after being dissolved in a solvent.

5. The polyisocyanate composition according to claim 4, characterized in that, The solvent is selected from any one or a combination of at least two of butyl acetate, ethyl acetate, solvent oil, toluene, xylene, propylene glycol methyl ether acetate, and diheptanone.

6. The polyisocyanate composition according to claim 4, characterized in that, The solvent accounts for 28-32% of the total mass of the polyisocyanate composition solution, which is 100% of the total mass.

7. The polyisocyanate composition according to claim 1, characterized in that, The NCO group content is 15-19% based on the total mass of the polyisocyanate composition of 100%.

8. The polyisocyanate composition according to claim 7, characterized in that, The NCO group content is 15.7-18.5% based on the total mass of the polyisocyanate composition of 100%.

9. The polyisocyanate composition according to claim 7, characterized in that, The polyisocyanate composition solution corresponding to the solution state after dissolving it in a solvent, with the total mass of the polyisocyanate composition solution being 100%, contains 11-13% NCO groups.

10. The polyisocyanate composition according to claim 1, characterized in that, The content of isophorone diisocyanate monomer is less than 0.5 wt%.

11. The polyisocyanate composition according to claim 10, characterized in that, The content of isophorone diisocyanate monomer is less than 0.35 wt%.

12. The polyisocyanate composition according to claim 11, characterized in that, The content of isophorone diisocyanate monomer is less than 0.1 wt%.

13. The application of the polyisocyanate composition according to any one of claims 1-12 in the fields of automotive refinish paints, automotive original equipment paints, rail transit coatings, hot melt adhesives, and solar backsheet adhesives.

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