Diisocyanate composition and application thereof

Abstract

The invention relates to the technical field of organic chemistry, in particular to a diisocyanate composition and application thereof. The diisocyanate composition comprises dicyclohexylmethane diisocyanate and a compound DN, and the content of the compound DN is less than or equal to 1% based on the total mass of the diisocyanate composition; the content of dicyclohexylmethane diisocyanate is greater than or equal to 99%; the mass percentage content of 2, 4 '-dicyclohexylmethane diisocyanate in the diisocyanate composition is less than or equal to 25%. The content of the compound DN and the content of the 2, 4 '-HMDI in the diisocyanate composition are jointly limited, so that the reaction activity of the diisocyanate composition and polyhydric alcohols is moderate, monomer residues can be effectively reduced, and meanwhile, the turbidity and color number of a reaction solution can be prevented from being increased.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of organic chemistry, in particular to a diisocyanate composition and application thereof. BACKGROUND

[0002] Dicyclohexylmethane diisocyanate (HMDI for short) is an aliphatic isocyanate. Due to the absence of benzene rings in its structure, it has excellent weather resistance and can be used to prepare high-grade polyurethane materials with light stability, weather resistance and excellent mechanical properties, such as thermoplastic polyurethane elastomers (TPU), waterborne polyurethane dispersions, photosensitive resins (UV resins) and the like.

[0003] In the above-mentioned fields, the reaction of HMDI with polyols is generally used as a basic reaction, and the reaction effect directly affects the quality of the subsequent polyurethane products. However, there are few public reports on the activity regulation of HMDI composition and polyol reaction. The existing patent document CN112592457B discloses a polyisocyanate composition, its preparation method and application, which mentions that by controlling the difference between the alkali-decomposition chlorine and the hydrolysis chlorine content in the polyisocyanate composition, the problem of unstable reaction activity and local over-reaction in the prepolymerization stage and chain extension stage during the synthesis of polyurethane resin can be solved. However, the scheme has the following problems: (1) the analysis precision of alkali-decomposition chlorine and hydrolysis chlorine reaches 0.1 ppm, which requires high electrochemical titration, and is not conducive to popularization and application; (2) it mainly focuses on the turbidity of the reaction solution, the light transmittance of the product and the yellowing resistance, and does not focus on the content of residual monomers. Excessive residual monomers can easily lead to the volatilization of residual HMDI, which can easily cause personnel allergies when contacting the human body; (3) from the implementation examples of the scheme, the purity of the polyisocyanate composition required is above 99.75%, which is higher than the requirement of 99.5% in the existing industry standard HG / T 6064-2022, which inevitably requires more cost in the synthesis of polyisocyanate.

[0004] Therefore, it is necessary to provide an HMDI composition that can overcome the above-mentioned defects, the composition index of which is easy to detect, the activity of which is moderate, the residual monomers in the product after reaction with polyols are less, and the turbidity and color number of the product after reaction are lower. SUMMARY

[0005] The present application provides a diisocyanate composition (i.e. HMDI composition) and application thereof, in order to solve the problems of unstable reaction activity of polyisocyanate composition and polyol, local over-reaction, excessive residual monomers, high purity requirement of the composition, and difficult detection of the composition index in the prior art.

[0006] In a first aspect, this application provides a diisocyanate composition comprising: dicyclohexylmethane diisocyanate and compound DN, wherein the dicyclohexylmethane diisocyanate comprises 2,4'-dicyclohexylmethane diisocyanate and 4,4'-dicyclohexylmethane diisocyanate; based on the total mass of the diisocyanate composition, the content of compound DN is ≤1%, and the content (i.e., purity) of the dicyclohexylmethane diisocyanate is ≥99%; based on the total mass of the diisocyanate composition, the content of 2,4'-dicyclohexylmethane diisocyanate (2,4'-HMDI) in the diisocyanate composition is ≤25%; The compound DN has the structure shown in the following general formula: , Among them, R1 and R2 are H or NCO, and R1 and R2 are different; R3 is selected from at least one of cyclohexyl, cyclohexenyl, and halocyclohexyl.

[0007] As an example, in the diisocyanate composition, the mass percentage of compound DN can be 0%, 0.001%, 0.005%, 0.01%, 0.05%, 0.1%, 0.3%, 0.5%, 0.7%, 0.9%, 1%, or within any range of the above values. The content or purity of the dicyclohexylmethane diisocyanate can be 99%, 99.1%, 99.2%, 99.3%, 99.5%, 99.6%, 99.7%, 99.8%, 99.9%, or within any range of the above values. The mass percentage of 2,4'-HMDI in the diisocyanate composition can be 0.1%, 0.5%, 1%, 3%, 5%, 7%, 9%, 10%, 12%, 14%, 15%, 17%, 19%, 20%, 22%, 25%, or within any range of the above values.

[0008] In one optional embodiment, the content of the dicyclohexylmethane diisocyanate is 99%-99.7%; more preferably, the content of the dicyclohexylmethane diisocyanate is 99%-99.5%.

[0009] This application reduces the concentration of HMDI in the composition by further limiting the content of dicyclohexylmethane diisocyanate, even to below the industry standard, thereby reducing the cost of product purification or refining during HMDI synthesis.

[0010] In one alternative embodiment, R3 is selected from at least one of cyclohexyl, cyclohexenyl, and chlorocyclohexyl.

[0011] In one optional embodiment, the compound DN includes at least one of compound DN-X and compound DN-C; In the compound DN-X, R3 is selected from at least one of cyclohexyl and cyclohexenyl; In the compound DN-C, R3 is selected from chlorocyclohexyl.

[0012] In one alternative embodiment, the compound DN-X comprises at least one of the compounds shown in the following structures: ; In one optional embodiment, the compound DN-C comprises at least one of the compounds shown in the following structures: .

[0013] In one alternative embodiment, the compound DN is compound DN-X.

[0014] In one alternative embodiment, the compound DN includes compound DN-X and compound DN-C.

[0015] In an optional embodiment, the compound DN is compound DN-C, and the mass percentage of 2,4'-dicyclohexylmethane diisocyanate is ≤12.1% based on the total mass of the diisocyanate composition.

[0016] Secondly, this application provides a method for preparing a polyurethane resin, wherein the raw materials include the above-mentioned diisocyanate composition.

[0017] In one alternative embodiment, the raw materials for preparing the polyurethane resin further include polyol compounds.

[0018] Thirdly, this application provides an application of the polyurethane resin prepared by the above preparation method in polyurethane elastomers, polyurethane optical materials, polyurethane coating materials, and polyurethane foams.

[0019] In an optional embodiment, this application achieves the control of the diisocyanate composition by adding compound DN-X and / or compound DN-C to conventional HMDI. All of the above substances can be prepared by methods known in the art.

[0020] The preparation method of conventional HMDI mentioned in this application is not limited; it can be synthesized using a phosgene process or a non-phosgene process. In the embodiments of this application, conventional HMDI is synthesized using a phosgene process.

[0021] The polyol compounds used in this application for testing the reactivity of HMDI can have a molecular weight of 400-20000. In the examples of this application, polypropylene glycol PPG-2000 (polypropylene glycol with a degree of polymerization of 2000), which is widely used in the market, is used.

[0022] In this application, the reaction of the HMDI composition with the polyol is an exothermic reaction. As the reaction proceeds, the viscosity of the reaction solution gradually increases, and the efficiency of heat removal decreases, leading to an increase in the temperature of the reaction system. This increases the reaction efficiency of the HMDI composition with the polyol. The increased reaction efficiency leads to a further acceleration of heat release, increased viscosity, further decrease in heat removal efficiency, and further increase in temperature. Ultimately, this may lead to local runaway of the reaction, resulting in the formation of polymers. Unreacted HMDI monomers are encapsulated by the polymers, forming monomer residues. The generated polymers also cause an increase in the turbidity of the reaction solution. Excessive heat release during runaway reaction can also cause an increase in the color of the reaction solution.

[0023] According to the inventors' research, when the HMDI composition containing compound DN provided in this application reacts with polyols, compound DN, being a monoisocyanate, acts as a terminator, slightly suppressing the reaction activity and preventing runaway reaction. Even if the reaction becomes locally uncontrolled and the temperature rises, the chlorine in compound DN-C will dissociate at high temperatures, poisoning the catalyst and reducing the overall reaction activity, thus keeping the reaction activity within an appropriate range. However, when the content of compound DN is too high, the excessive monoisocyanate's terminating effect prevents the reaction from continuing, resulting in excessively high residual monomer levels in the system. Furthermore, the inventors' research also found that due to the difference in reactivity between the isomers 2,4'-HMDI and 4,4'-HMDI in HMDI, excessively high levels of 2,4'-HMDI can easily lead to higher residual monomer levels at the reaction endpoint under the same reaction conditions. Therefore, by limiting the content of compounds DN and 2,4'-HMDI in the HMDI composition, this application ensures that the HMDI composition has moderate reactivity with polyols, effectively reducing monomer residues, while also preventing an increase in turbidity and color of the reaction solution.

[0024] The technical solution of this application has the following advantages: 1. The diisocyanate composition provided in this application comprises: dicyclohexylmethane diisocyanate and compound DN, wherein the dicyclohexylmethane diisocyanate includes 2,4'-dicyclohexylmethane diisocyanate and 4,4'-dicyclohexylmethane diisocyanate; based on the total mass of the diisocyanate composition, the content of compound DN is ≤1%, and the content of dicyclohexylmethane diisocyanate is ≥99%; based on the total mass of the diisocyanate composition, the content of 2,4'-dicyclohexylmethane diisocyanate is ≤25%. By limiting the content of both compound DN and 2,4'-HMDI in the diisocyanate composition, this application achieves moderate reactivity of the diisocyanate composition with polyols, effectively reducing monomer residue in the post-reaction product, while also preventing an increase in turbidity and color of the reaction solution. In addition, this application does not have high requirements for the concentration of HMDI in the diisocyanate composition, and even reduces it to below the industry standard, thereby reducing the cost input in the HMDI synthesis process; furthermore, the content of compounds DN and 2,4'-dicyclohexylmethane diisocyanate in the diisocyanate composition can be detected by conventional gas chromatography in the field, which reduces the requirements for detection instruments and facilitates its widespread application.

[0025] 2. The diisocyanate composition provided in this application, by further limiting the content of compounds DN and 2,4'-HMDI in the HMDI composition, can further reduce the cost input in the HDMI synthesis process.

[0026] 3. The diisocyanate composition provided in this application, wherein the compound DN is compound DN-C, and the mass percentage of 2,4'-dicyclohexylmethane diisocyanate is ≤12.1% based on the total mass of the diisocyanate composition. This application achieves lower monomer residues by further limiting the content of compounds DN and 2,4'-HMDI.

[0027] 4. The polyurethane resin preparation method provided in this application uses the diisocyanate composition provided above, which has moderate reactivity with polyol compounds, effectively reducing monomer residue in the product after reaction and avoiding HMDI volatilization and its impact on human health; at the same time, it can also avoid the increase of turbidity and color number of the reaction liquid, and improve the light transmittance and yellowing resistance of the product.

[0028] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0030] Figure 1 This is the mass spectrum of compound DN-X in the embodiments of this application; Figure 2 This is the mass spectrum of compound DN-C in the embodiments of this application. Detailed Implementation

[0031] The following embodiments are provided to better understand this application. However, the following embodiments do not constitute a limitation on the content and scope of protection of this application. Any product that is the same as or similar to this application, derived by anyone under the guidance of this application or by combining the features of this application with other prior art, falls within the scope of protection of this application.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having” and any variations thereof in the text of this application are intended to cover non-exclusive inclusion.

[0033] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0034] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the specific range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers from a to b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed herein, and "0-5" is merely a shortened representation of these numerical combinations. Furthermore, when a parameter is described as an integer ≥ 2, it is equivalent to disclosing that the parameter can be, for example, integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0035] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0036] In the description of the embodiments of this application, the term "at least one" refers to one or more (including two).

[0037] Unless otherwise specified, all experimental steps or conditions in the examples were performed according to conventional experimental procedures and conditions in the art. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0038] The present application will now be described with reference to specific embodiments. It should be noted that these embodiments are merely descriptive and do not limit the present application in any way.

[0039] In this application, the qualitative analysis method of compounds DN-X and DN-C using gas chromatography-mass spectrometry is as follows: Analytical instrument: Gas chromatography-mass spectrometry; Gas chromatography conditions: Column: DB-5 MS UI (30m × 0.25mm × 0.25μm); Column flow rate: 1 mL / min (high-purity helium, purity greater than 99.999%) Column temperature: 140℃ held for 0 min, then increased to 220℃ at a rate of 10℃ / min, held for 1 min, then increased to 260℃ at a rate of 5℃ / min, held for 0 min, then increased to 280℃ at a rate of 10℃ / min, held for 1 min. Injection volume: 0.2 uL; Flow split ratio: 50:1; Inlet temperature: 270℃; Transmission line temperature: 290℃; Agilent 8890-7250 GC-QTOF high-resolution mass spectrometer: ion source is LE-EI, ion source temperature is 200℃, quadrupole temperature is 150℃, ionization source energy is 70 eV, and full scan profile acquisition is performed in single-stage mass spectrometry mode, with a mass acquisition range of 50-600.

[0040] In the gas chromatography-mass spectrometry analysis, the typical molecular ion peak (m / z) of DN-X is between 219.1596 and 219.1640, with the molecular formula C. 14 H 21 ON; simultaneously, the mass-to-charge ratio (m / z) shows peaks at 176.1547–176.1583. A typical mass spectrum of compound DN-X is shown below. Figure 1 As shown.

[0041] In the gas chromatography-mass spectrometry analysis, the molecular ion peak (m / z) of compound DX-C was between 255.1358 and 255.1410, and its molecular formula is C. 14 H 22 ONCl; the mass-to-charge ratio (m / z) also shows peaks at 220.1674–220.1718 and 212.1311–212.1353. A typical mass spectrum of the compound DN-C is shown below. Figure 2 As shown.

[0042] The gas chromatographic quantitative analysis of compounds DN-X and DN-C was performed according to the following method: Analytical instrument: Gas chromatograph; Column: DB-5 (30m × 0.32mm × 0.25μm); Column flow rate: 1 mL / min (high-purity nitrogen, purity greater than 99.999%). Column temperature: 140℃ held for 0 min, then increased to 220℃ at a rate of 10℃ / min, held for 1 min, then increased to 260℃ at a rate of 5℃ / min, held for 0 min, then increased to 280℃ at a rate of 10℃ / min, held for 1 min. Injection volume: 0.5 μL; Flow split ratio: 30:1; Inlet temperature: 270°C; FID detector parameters: temperature 290℃; combustion gas (hydrogen): 30 mL / min; combustion gas (air): 400 mL / min; tail gas (nitrogen): 30 mL / min.

[0043] The raw materials for the diisocyanate compositions in the following examples and comparative examples of this application were prepared in the laboratory using the following methods: (1) Preparation of conventional HMDI compositions HMDA-1: A Wanhua Chemical product in the HMDA series. This HMDA composition contains 35 wt% 2,4'-diaminodicyclohexylmethane (2,4'-HMDA) and 65 wt% 4,4'-diaminodicyclohexylmethane (4,4'-HMDA). HMDA-2: A product in the HMDA series manufactured by Wanhua Chemical. This HMDA composition contains 0.1 wt% 2,4'-HMDA and 99.9 wt% 4,4'-HMDA. Using a vaporizer, HMDA-1 (or HMDA-2) is vaporized and heated to 355°C. Under nitrogen protection, it and gaseous phosgene heated to 355°C are continuously added to the reactor through their respective feed pipes for phosgenation reaction. The reaction pressure is absolute 70 kPa, and the reaction temperature is 355°C. The feed rate of HMDA is 800 kg / h, and the feed rate of gaseous phosgene is 3900 kg / h. The mixed gas obtained after the reaction is rapidly cooled to 100°C using an o-dichlorobenzene solution through a gas jet absorption device to obtain a crude product containing HMDI, phosgene, and o-dichlorobenzene solution. It should be noted that the isomers do not change during the phosgenation reaction of HMDA to HMDI. The change in the amount of isomers is mainly due to the removal of some isomers entrained by impurities during the separation process.

[0044] The crude product was treated to remove phosgene and o-dichlorobenzene solution. The o-dichlorobenzene solution and excess phosgene in the crude product were removed at 168°C and 0.1 MPa absolute pressure to obtain HMDI-1 crude product (or HMDI-2 crude product) that does not contain phosgene. The crude HMDI-1 (or HMDI-2 crude product) is purified by passing it through a 15-plate distillation column to obtain the HMDI-1 product (or HMDI-2 product) under an absolute pressure of 0.5 kPa and a distillation range of 180-200 °C.

[0045] Using the gas chromatography method provided by industry standard HG / T 6064-2022, the composition of HMDI-1 obtained by HMDA-1 was analyzed, which included 34.74 wt% 2,4'-HMDI and 65.17 wt% 4,4'-HMDI. The composition of HMDI-2 obtained by HMDA-2 was analyzed, which included 0.06 wt% 2,4'-HMDI and 99.82 wt% 4,4'-HMDI.

[0046] (2) Preparation of HMDI containing compound DN-X The HMDI-1 product prepared by the above method was heated at 250℃ for 2 hours under nitrogen protection, and then distilled at 0.5 kPa using a distillation column with 8-10 trays. The fraction collected between 125-155℃ was identified as HMDI-X. Gas chromatography analysis revealed that the content of compound DN-X was 2.25%, the content of HMDI was 97.71%, and the content of 2,4'-HMDI was 45.17%.

[0047] (3) Preparation of HMDI containing compound DN-C Using the HMDA-1 product prepared by the above method as raw material, a 10% solution of HMDA-1 and dioxane was prepared with dioxane as solvent. Water of equal mass to HMDA-1 was added to the solution. Using palladium metal (Al2O3 as support) as catalyst, the catalyst addition amount was 1% (based on the molar amount of HMDA-1). Under nitrogen protection, the solution was heated at 180℃ for 6 hours to obtain HMDA-1 with hydroxyl groups replacing the amino groups. The solution was heated to 120℃ at -20 kPaG to remove the solvent and excess water by distillation. Then, it was phosgenated according to the phosgenation method in step (1) to obtain HMDI composition HMDI-C containing compound DN-C. Gas chromatography analysis showed that the content of compound DN-C was 1.77%, the content of HMDI was 98.23%, and the content of 2,4'-HMDI was 34.2%.

[0048] Examples 1-14 This embodiment provides a diisocyanate composition, which is obtained by blending different specifications of HMDI compositions prepared above. HMDI-1, HMDI-2, HMDI-X, and HMDI-C are blended according to the proportions in the table below to obtain diisocyanate compositions of different specifications.

[0049] Table 1 Composition of diisocyanate composition

[0050] Note: In the samples in the table above, less than 100% are other impurities, such as hydrolyzed chlorine.

[0051] Comparative Examples 1-10 The diisocyanate compositions provided in Comparative Examples 1-10 of this application were obtained by blending different specifications of HMDI compositions prepared above. HMDI-1, HMDI-2, HMDI-X, and HMDI-C were blended according to the proportions in Table 1 to obtain diisocyanate compositions of different specifications.

[0052] Experimental Example 1 (1) Evaluation of the reactivity of diisocyanate composition with polyol a) Dilute the catalyst dilauryl dibutyltin (T12) with toluene to a concentration of 1% and set aside for later use; b) Add 67.5g of PPG-2000 with a moisture content of 300ppm to a 500ml reactor, place the reactor in an 82℃ oil bath, and start stirring to preheat it at a stirring speed of 180r / min. c) After the temperature inside the reactor reaches 80°C, add 0.3g of the catalyst T12 prepared in step a) and 8.9g of the diisocyanate compositions provided in each example and comparative example to the reactor, and carry out the reaction; d) During the reaction process, samples are taken every 5 minutes to monitor the NCO content. When the NCO content no longer decreases, the reaction is considered to have stopped, heating is stopped, and the reaction time is recorded. e) Once the reactor temperature has dropped to room temperature, the residual monomer content is determined by GPC (molecular gel chromatography). The specific test conditions are as follows: GPC equipment: Agilent 1260; GPC column: Pl1113-6520 and Pl113-6325 (Agilent); sample concentration: 3wt%; mobile phase: tetrahydrofuran; detection method: differential detector; flow rate: 1ml / min; column temperature: 35℃; its color number was measured by the method of GB / T605-2006; its turbidity was measured by the method of GB / T15893.1-2014, as follows: (1) Instruments and equipment: scattered light turbidity meter; light source: tungsten filament lamp equipped with monochromator, or monochromatic light-emitting diode, or monochromatic laser, or visible light source can also be used; incident light: wavelength 860nm, bandwidth not greater than 60nm, emission or concentration not exceeding 1.5°; measurement angle: the angle between the incident light axis and the scattered light axis is 90°±2.5; receiver: the aperture angle at the center of the water sample is between 20° and 30°. (2) Analysis steps: Debugging: Debug the instrument according to the turbidity meter instruction manual; Positioning: Select a formalazine turbidity standard solution whose turbidity value is close to that of the water sample to be tested, and repeatedly zero and position it with water until it is stable; Measurement: Shake the water sample well, wait for the bubbles to disappear, and inject the water sample into the test tube of the turbidity meter for measurement. Read the turbidity value directly from the instrument. If the water sample has a large color, filter the measured water sample through slow quantitative filter paper or a glass frit funnel with a pore size of 2μm~5μm, and then measure the filtered water sample. The original water sample measurement value minus the filtered water sample measurement value is the turbidity of the water sample to be tested. (3) Expression of analysis results: Report the results in formalazine turbidity units (NTU).

[0053] The specific test results are shown in the table below: Table 2 Test Results

[0054] The results in the table above show that by limiting the content of compounds DN and 2,4'-HMDI in the diisocyanate composition, this application achieves moderate reactivity between the diisocyanate composition and the polyol, effectively reducing monomer residue and preventing an increase in turbidity and color of the reaction solution, demonstrating a significant advantage compared to the comparative example. Furthermore, it can reduce the concentration of HMDI in the composition, even below industry standards, thus reducing costs in the synthesis process. The reaction time in the table corresponds to the reactivity; shorter times result in higher reactivity, potentially leading to turbidity, monomer encapsulation, and high residual monomer levels. Longer times result in lower reactivity, incomplete monomer reaction, and potentially higher color and residual monomer levels in the reaction solution. Therefore, appropriate reactivity is necessary.

[0055] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A diisocyanate composition, characterized in that, Comprising: dicyclohexylmethane diisocyanate including 2,4'-dicyclohexylmethane diisocyanate and 4,4'-dicyclohexylmethane diisocyanate; content of the compound DN is ≤1%, content of the dicyclohexylmethane diisocyanate is ≥99% based on the total mass of the diisocyanate composition; content of 2,4'-dicyclohexylmethane diisocyanate is ≤25% based on the total mass of the diisocyanate composition; The compound DN has the structure shown in the following general formula: ， wherein R1 and R2 are H or NCO, R1 and R2 are not the same; R3 is selected from at least one of cyclohexyl, cyclohexenyl, halogenated cyclohexyl.

2. The diisocyanate composition of claim 1, wherein, R3 is selected from at least one of cyclohexyl, cyclohexenyl, chlorocyclohexyl.

3. The diisocyanate composition of claim 1, wherein, The compound DN includes at least one of compound DN-X and compound DN-C. In the compound DN-X, R3 is selected from at least one of cyclohexyl and cyclohexenyl. In the compound DN-C, R3 is selected from chlorocyclohexyl.

4. The diisocyanate composition of claim 3, wherein, The compound DN-X includes at least one of the compounds shown in the following structures: ； and / or, the compound DN-C includes at least one of the compounds shown in the following structures: 。 5. The diisocyanate composition according to any one of claims 1 to 3, characterized in that, The compound DN is compound DN-X.

6. The diisocyanate composition according to any one of claims 1 to 3, characterized in that, The compound DN includes compound DN-X and compound DN-C.

7. The diisocyanate composition according to any one of claims 1 to 3, characterized in that, The compound DN is compound DN-C, and the mass percentage content of 2,4'-dicyclohexylmethane diisocyanate is ≤12.1% based on the total mass of the diisocyanate composition.

8. A method for producing a polyurethane resin, characterized by, The raw material includes the diisocyanate composition according to any one of claims 1-7.

9. The method of claim 8, wherein the polyurethane resin is prepared by reacting a polyisocyanate with a polyol in the presence of a chain extender. The raw material for preparing the polyurethane resin further includes a polyol compound.

10. Use of the polyurethane resin prepared by the preparation method according to any one of claims 8 or 9 in polyurethane elastomers, polyurethane optical materials, polyurethane coating materials and polyurethane foams.

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