Isocyanate composition, modified isocyanate, polyurethane resin and optical material

Abstract

The invention provides an isocyanate composition, modified isocyanate, polyurethane resin and an optical material. The effective factor of the isocyanate composition is 3.90-5.70. According to the invention, through design and control of effective factors, the catalyst has excellent reaction activity, can be used for preparation of resins such as high-performance polyurethane, polythionocarbamate and the like, and does not generate undesirable phenomena such as gel in a polymerization process. Moreover, the isocyanate composition can effectively improve the yellowing resistance, the stability and the optical performance of products such as polyurethane and polythionocarbamate, so that the obtained polyurethane and polythionocarbamate do not generate white turbidity and opaque phenomena. The optical material prepared from the isocyanate composition has significantly reduced yellowness index and significantly reduced optical deformation occurrence rate, and the optical properties of the optical material are effectively improved.

Description

[0001] This application is a divisional application. The application number of its parent application is 202211460526.9, the application date is November 17, 2022, and the invention title is "An Isocyanate Composition, Modified Isocyanate, Polyurethane Resin and Optical Material". Technical Field

[0002] The present invention belongs to the technical field of isocyanates, and specifically relates to an isocyanate composition, a modified isocyanate, a polyurethane resin and an optical material. Background Art

[0003] Compared with inorganic optical materials such as glass, optical resin materials have the advantages of light weight, not being easily broken, not being easily cracked, and being easily dyed, and are widely used in fields such as spectacle lenses, mobile phone lenses, lighting fixtures, lenses, prisms, and electrical equipment. Currently known optical resin materials include polycarbonate (PC), polymethyl methacrylate (acrylic, PMMA), polyallyl diglycol carbonate resin (PADC), and polythiourethane, etc. Among them, polythiourethane has excellent comprehensive performance in terms of transparency, refractive index, impact resistance, dyeability, and processability, and is one of the most promising optical materials.

[0004] Polythiourethane belongs to an important branch of polyurethane materials, which is obtained by the polymerization reaction of polythiol compounds and polyisothiocyanate compounds. For example, CN101155848A discloses a polythiourethane-based polymerizable composition, including the following components: (A) an alicyclic isocyanate compound, (B) an aliphatic isocyanate compound, (C) at least one of a polythiol compound having one or more sulfur bonds in one molecule or a polythiol compound having one or more polysulfide bonds in one molecule, (D) a polyhydroxy compound having two or more hydroxyl groups in one molecule, and / or at least one of a hydroxy mercapto compound having one or more hydroxyl groups and one or more mercapto groups; the polythiourethane obtained from this polymerizable composition has good dyeability and strength. CN106414538A discloses a composition for preparing a transparent polythiourethane body, including a polyisocyanate component, a thiol component, and optional auxiliaries and additives; wherein, the polyisocyanate component is prepared by the gas-phase phosgenation of an aliphatic, alicyclic, aromatic, or araliphatic polyamine, and it contains at least 0.005% by weight of at least one nitrile substance based on the polyisocyanate component, and this nitrile substance and the polyisocyanate are derived from the same polyamine; the polythiourethane lens prepared from the foregoing composition has good transparency. CN108084386A discloses a polythiourethane resin composition for optical materials, which is obtained by heating and curing a composition containing an organic zirconium bismuth alloy complex, an isocyanate compound, and a thiol compound; wherein, the organic zirconium bismuth alloy complex is used as a catalyst, which can improve the qualification rate in the industrialization process of lens products without losing the transparency, mechanical properties, heat resistance and other resin properties of plastic lens applications.

[0005] The polythiourethanes disclosed in the prior art mainly focus on the transparency, mechanical properties, dyeability, heat resistance, etc. of the materials. However, during the polymerization process of polythiourethane materials, phenomena such as resin turbidity and opacity often occur, and the obtained polythiourethane has problems such as yellowing and optical deformation, resulting in unqualified quality of products such as lenses and lenses, which severely limits the wide application of polythiourethane in optical components such as lenses and lenses.

[0006] Therefore, developing polythiourethanes with more excellent properties, especially reducing the yellowness index and the incidence of optical deformation of polythiourethane, is an urgent problem to be solved in this field. Summary of the Invention

[0007] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide an isocyanate composition, a modified isocyanate, a polyurethane resin, and an optical material. Through the design and control of effective factors, the isocyanate composition can effectively improve the yellowing resistance and stability of the polyurethane resin and polythiourethane, significantly reduce the yellowness index and the incidence of optical deformation of the optical material, and endow it with excellent optical properties.

[0008] To achieve the object of this invention, the following technical solutions are adopted in this invention:

[0009] In the first aspect, this invention provides an isocyanate composition, and the effective factor of the isocyanate composition is 3.90 - 5.70.

[0010] The calculation formula of the effective factor is shown in Formula I:

[0011]

[0012] In Formula I, E is the effective factor;

[0013] In Formula I, A is the mass content of chlorine in the isocyanate composition;

[0014] In Formula I, B is the mass content of chloro isocyanate in the isocyanate composition;

[0015] In Formula I, M Cl is the relative atomic mass of chlorine;

[0016] In Formula I, M B is the relative molecular mass of the chloro isocyanate.

[0017] The effective factor E of the isocyanate composition provided by this invention is 3.90 - 5.70. For example, it can be 4.00, 4.10, 4.30, 4.50, 4.70, 4.90, 5.00, 5.10, 5.20, 5.30, 5.40, 5.50 or 5.60, as well as the specific point values between the above point values. Due to space limitations and for the sake of brevity, this invention does not list all the specific point values included in the range.

[0018] In the present invention, the isocyanate composition includes a combination of an isocyanate and a chlorine-containing substance, so it is defined as a "composition"; the chlorine-containing substance includes a chloro isocyanate and a substance corresponding to an effective factor. Through the design and control of the effective factor, the isocyanate composition in the present invention includes a specific type of chlorine-containing substance with a specific content, making it have excellent reactivity and capable of being used in the preparation of high-performance polyurethane, polythiourethane and other resins, and no adverse phenomena such as gelation will occur during the polymerization process; moreover, the isocyanate composition can effectively improve the yellowing resistance, stability and optical properties of resin products such as polyurethane and polythiourethane, so that the obtained polyurethane and polythiourethane will not show turbidity or opacity, and as an optical material, it has a low yellowness index and a low incidence of optical deformation, effectively improving the optical quality of the optical material. If the effective factor is too high, when the isocyanate composition is used to prepare polyurethane or polythiourethane, gelation will occur during the polymerization reaction; if the effective factor is too low, it will affect the yellowing resistance and optical properties of polyurethane and polythiourethane, resulting in a higher yellowing index of the optical material and an increased probability of optical deformation.

[0019] In the present invention, in formula I for calculating the effective factor, A is the mass content of chlorine in the isocyanate composition, preferably obtained by testing with X-ray fluorescence spectrometry (XRF).

[0020] Preferably, in formula I for calculating the effective factor, B is the mass content of chloro isocyanate in the isocyanate composition, obtained by chromatography-mass spectrometry testing, preferably by gas chromatography-mass spectrometry (GCMS) testing.

[0021] In the research of the present invention, it is found that the existing methods for characterizing the chlorine content in isocyanates known in the prior art cannot accurately control the performance of isocyanates, and thus cannot effectively control the quality of polyurethane / polythiourethane, especially the yellowing resistance and optical properties. Specifically, in standard GB / T 12009.1-1989, the test method for the total chlorine content is the oxygen flask combustion method. All chlorine (including bromine) in the isocyanate is converted into inorganic chlorine (including bromine) and then titrated with silver nitrate, which characterizes all the chlorine content in the isocyanate and also includes the bromine content in the isocyanate. Standard GB / T 12009.2-2016 measures the hydrolyzable chlorine, specifically the chlorine released after the reaction of the isocyanate with alcohol and water, which is the more reactive chlorine in the isocyanate and also includes the more reactive bromine. Some monochloro isocyanates can also hydrolyze a part. The chlorine (including a part of bromine) content measured by GB / T 12009.1-1989 or GB / T 12009.2-2016 cannot accurately represent the component information of the isocyanate, and thus cannot effectively control the performance of the isocyanate and polyurethane / polythiourethane.

[0022] As a preferred technical solution of the present invention, in the calculation of the effective factor E, A is the total chlorine content (excluding bromine) obtained by XRF test, and B is the content of chloro isocyanate obtained by chromatograph-mass spectrometry. The values of A and B are obtained by precise qualitative and quantitative analysis methods, so that the effective factor E accurately characterizes the polychlorinated substances and partial hydrolyzed chlorine (excluding the hydrolyzed chlorine of monochloro isocyanate) in the isocyanate composition, corresponding to a more refined and clear chlorine content. This part of the chlorine content plays a key role in the activity of the isocyanate and the properties of products such as polyurethane and polythiourethane, thereby realizing the performance regulation of the isocyanate composition, and further improving the properties of polyurethane and polythiourethane prepared therefrom. In particular, it has an obvious improvement effect on the optical properties (yellowing index, optical distortion) of optical materials.

[0023] Preferably, the isocyanate is a diisocyanate, and further preferably includes any one or at least two combinations of xylylene diisocyanate (XDI), bis(isocyanatomethyl)cyclohexane (H6XDI), and bis(isocyanatomethyl)norbornane (NBDI).

[0024] In the present invention, unless otherwise specified, the listed isocyanates include all their isomers. For example, the xylylene diisocyanate (XDI) is The bis(isocyanatomethyl)cyclohexane (H6XDI) is The bis(isocyanatomethyl)norbornane (NBDI) is

[0025]

[0026] Preferably, the mass percentage content of isocyanate in the isocyanate composition is ≥97%, such as 97.5%, 98%, 98.5%, 99%, 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, 99.9%, 99.92%, 99.95%, 99.98%, 99.99%, etc.

[0027] Preferably, the mass content of chlorine (A value) in the isocyanate composition is 2 - 1000 ppm, for example, it can be 5 ppm, 10 ppm, 50 ppm, 100 ppm, 150 ppm, 200 ppm, 250 ppm, 300 ppm, 350 ppm, 400 ppm, 450 ppm, 500 ppm, 550 ppm, 600 ppm, 650 ppm, 700 ppm, 750 ppm, 800 ppm, 850 ppm, 900 ppm or 950 ppm, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the specific point values included in the scope of the present invention are not exhaustively listed herein. Further preferably, it is 15 - 500 ppm.

[0028] In the present invention, "ppm" is parts per million ratio, and 1 ppm represents one millionth; when the same expression is involved hereinafter, it has the same meaning.

[0029] Preferably, the substance corresponding to the effective factor includes any one or a combination of at least two of the following compounds: Among them, R is a divalent group obtained by removing the NCO group in the isocyanate.

[0030] Preferably, the R is selected from (when the isocyanate is XDI), (when the isocyanate is H6XDI), (when the isocyanate is NBDI), any one or a combination of at least two of them; where the wavy line represents the connection site of the group.

[0031] Preferably, the chloro - isocyanate is a compound in which one NCO group in the isocyanate is replaced by chlorine.

[0032] Preferably, the chloro - isocyanate includes (chloromethylbenzyl isocyanate CBI, when the isocyanate is XDI), (chloromethyl isocyanatomethyl cyclohexane CIC, when the isocyanate is H6XDI), (chloromethyl isocyanatomethyl norbornane CNBI, when the isocyanate is NBDI), any one or a combination of at least two of them.

[0033] In this article, the expression of the ring structure crossed by "—" indicates that the connection site is at any bond - forming position on the ring structure.

[0034] Preferably, the mass content (B value) of the chloro isocyanate in the isocyanate composition is 10 - 2000 ppm, for example, it can be 20 ppm, 50 ppm, 100 ppm, 300 ppm, 500 ppm, 700 ppm, 900 ppm, 1000 ppm, 1100 ppm, 1300 ppm, 1500 ppm, 1700 ppm or 1900 ppm, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the range. Further preferably, it is 80 - 1500 ppm.

[0035] It should be noted that in the present invention, the substances corresponding to the effective factor, chloro isocyanate, can be produced as by-products during the preparation of isocyanate, or can be artificially added to obtain the required content.

[0036] In a second aspect, the present invention provides a method for preparing the isocyanate composition as described in the first aspect. The preparation method includes: reacting an amine compound with phosgene to obtain the isocyanate composition.

[0037] Preferably, the preparation method includes the following steps:

[0038] (1) Reacting an amine compound with phosgene to obtain a reaction product;

[0039] (2) Performing a removal treatment on the reaction product obtained in step (1) to obtain a crude product; the removal treatment includes phosgene removal treatment and / or solvent removal treatment;

[0040] (3) Separating and refining the crude product obtained in step (2) in sequence to obtain the isocyanate composition.

[0041] Preferably, in step (3), the separation obtains a heavy fraction and an intermediate product; the mixture of the intermediate product and the heavy fraction is refined to obtain the isocyanate composition; the mass percentage content of the heavy fraction in the mixture is 1 - 10%.

[0042] As a preferred technical solution of the present invention, the component for refining is the mixture of the intermediate product and the heavy fraction, and the mass percentage content of the heavy fraction in the mixture is 1 - 10%, for example, it can be 2%, 3%, 4%, 5%, 6%, 7%, 8% or 9%, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the range. Further preferably, it is 2 - 10%.

[0043] Preferably, the separated heavy components can be directly mixed with the intermediate product to obtain a mixture; or, the separated heavy components are primary heavy components, and the primary heavy components are separated again to obtain a heavy component recovery material and residual heavy components; the heavy component recovery material is mixed with the intermediate product to obtain the mixture; the mass percentage content of the heavy component recovery material in the mixture is 1-10%.

[0044] In another preferred technical solution, the preparation method of the isocyanate composition includes: mixing the isocyanate obtained by the carbamate cleavage method with the heavy component recovery material to obtain the isocyanate composition. Preferably, the mass percentage content of the heavy component recovery material in the isocyanate composition is 1-10% (such as 2%, 3%, 4%, 5%, 6%, 7%, 8% or 9%, etc.), and more preferably 1-5%.

[0045] As a preferred technical solution of the present invention, the preparation method of the isocyanate composition is the phosgenation method, that is, an amine compound reacts with phosgene to generate isocyanate; the amine compound includes diamine and / or diamine salt (such as the diamine hydrochloride obtained by reacting diamine with HCl).

[0046] Preferably, the method for reacting the amine compound with phosgene exemplarily includes the following three categories: the method of reacting diamine with phosgene in the gas phase, also known as the gas-phase phosgenation method; the method of reacting diamine with phosgene in the liquid phase, also known as the liquid-phase phosgenation method; the method of reacting a diamine salt (such as diamine hydrochloride) with phosgene in a solvent, also known as the phosgenation method of diamine hydrochloride, and more preferably the phosgenation method of diamine hydrochloride.

[0047] Preferably, the amine compound in step (1) is diamine hydrochloride.

[0048] Preferably, the diamine hydrochloride is prepared by a salification process, and the salification process includes: in the presence of a reaction solvent, reacting diamine with hydrogen chloride to obtain the diamine hydrochloride. What is actually obtained in the salification process is a slurry containing diamine hydrochloride, and this slurry is directly applied to the reaction with phosgene (isocyanate chemical process).

[0049] Preferably, the salification process specifically includes: introducing hydrogen chloride gas into the reaction solvent, then adding an amine solution (including the reaction solvent and diamine), stirring and mixing, and performing a salification reaction to obtain the diamine hydrochloride.

[0050] Preferably, the molar ratio of hydrogen chloride to diamine in the salification step is (2 - 20):1, for example, it can be 2.5:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1 or 18:1, etc., and more preferably (3 - 16):1.

[0051] Preferably, the mass percentage of diamine in the amine solution is 1 - 50 wt.%, for example, it can be 2 wt.%, 5 wt.%, 8 wt.%, 10 wt.%, 12 wt.%, 15 wt.%, 18 wt.%, 20 wt.%, 22 wt.%, 25 wt.%, 28 wt.%, 30 wt.%, 35 wt.%, 40 wt.%, 45 wt.% or 48 wt.%, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the above range. More preferably, it is 3 - 30 wt.%.

[0052] Preferably, the temperature of the salification reaction is 0 - 160 °C, for example, it can be 5 °C, 10 °C, 20 °C, 30 °C, 40 °C, 50 °C, 60 °C, 80 °C, 100 °C, 110 °C, 130 °C or 150 °C, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the above range. More preferably, it is 10 - 150 °C, and even more preferably 10 - 140 °C.

[0053] Preferably, the salification step is carried out under normal pressure or pressurized conditions.

[0054] Preferably, the pressure (gauge pressure) of the salification step is 0.01 - 1.0 MPa G, for example, it can be 0.03 MPa G, 0.05 MPa G, 0.08 MPa G, 0.1 MPa G, 0.2 MPa G, 0.3 MPa G, 0.4 MPa G, 0.5 MPa G, 0.6 MPa G, 0.7 MPa G, 0.8 MPa G or 0.9 MPa G, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the above range. More preferably, it is 0.02 - 0.5 MPa G, and even more preferably 0.02 - 0.4 MPa G.

[0055] Preferably, step (1) specifically includes: introducing phosgene into the diamine hydrochloride (slurry) for reaction to obtain a reaction product, i.e., a reaction solution containing diisocyanate.

[0056] Preferably, the molar ratio of phosgene to diamine hydrochloride is (4 - 50):1, for example, it can be 5:1, 8:1, 10:1, 12:1, 15:1, 18:1, 20:1, 22:1, 25:1, 28:1, 30:1, 32:1, 35:1, 38:1, 40:1, 42:1, 45:1 or 48:1, etc. Further preferably, it is (5 - 40):1, and even more preferably, it is (5 - 30):1.

[0057] Preferably, the temperature of the reaction in step (1) is 80 - 180 °C, for example, it can be 90 °C, 100 °C, 110 °C, 120 °C, 130 °C, 140 °C, 150 °C, 160 °C or 170 °C, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the above range. Further preferably, it is 100 - 170 °C, and even more preferably, it is 100 - 160 °C.

[0058] Preferably, the reaction time in step (1) is 2 - 25 h, for example, it can be 3 h, 4 h, 6 h, 8 h, 10 h, 12 h, 14 h, 16 h, 18 h, 20 h, 22 h or 24 h, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the above range. Further preferably, it is 4 - 20 h.

[0059] Preferably, the reaction in step (1) is carried out under normal pressure or pressurized conditions.

[0060] Preferably, the pressure (gauge pressure) of the reaction in step (1) is 0 - 0.6 MPa G, for example, it can be 0.0005 MPa G, 0.001 MPa G, 0.003 MPa G, 0.01 MPa G, 0.02 MPa G, 0.03 MPa G, 0.05 MPa G, 0.07 MPa G, 0.09 MPa G, 0.1 MPa G, 0.2 MPa G, 0.3 MPa G, 0.4 MPa G or 0.5 MPa G, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the above range. Further preferably, it is 0.005 - 0.4 MPa G, and even more preferably, it is 0.01 - 0.2 MPa G.

[0061] Preferably, the reaction in step (1) (isocyanate chemical process) is a batch process or a continuous process, and a continuous process is preferred.

[0062] Among them, the continuous process is that the slurry (diamine hydrochloride) generated in the salification process (salification kettle) is continuously transported from the stirring tank to a reaction kettle different from the salification kettle, and in the reaction kettle, the diamine hydrochloride reacts with phosgene, and the obtained reaction product (reaction liquid containing diisocyanate) is continuously taken out from the reaction kettle. The present invention does not specifically limit the number of reaction kettles for the continuous process. Exemplarily, it can be 2, 3, 4, 5 or more.

[0063] According to needs, a removal process (solvent removal process and / or phosgene removal process) and a separation and purification process can be carried out on the reaction product obtained in step (1).

[0064] Preferably, the reaction solvent is an organic solvent, exemplarily including but not limited to: aromatic hydrocarbons such as benzene, toluene, xylene, etc.; aliphatic hydrocarbons such as octane, decane, etc.; cycloaliphatic hydrocarbons such as cyclohexane, methylcyclohexane, ethylcyclohexane, etc.; halogenated aromatic hydrocarbons such as chlorotoluene, chlorobenzene, dichlorobenzene, dibromobenzene, trichlorobenzene, etc.; nitrogen-containing compound classes such as nitrobenzene, N,N-dimethylformamide, N,N-dimethylacetamide, N,N'-dimethylimidazolidinone, etc.; ethers such as dibutyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, etc.; ketones such as heptanone, diisobutyl ketone, methyl isobutyl ketone, methyl ethyl ketone, etc.; fatty acid esters such as ethyl acetate, butyl acetate, amyl acetate, ethoxyethyl acetate, etc.; aromatic carboxylic acid esters such as methyl salicylate, dimethyl phthalate, dibutyl phthalate, methyl benzoate, etc.; The reaction solvent can be used alone or as a combination of at least two.

[0065] Preferably, the reaction solvent includes halogenated aromatic hydrocarbons, and further preferably chlorobenzene and / or dichlorobenzene.

[0066] Preferably, the phosgene removal treatment in step (2) is carried out in a phosgene removal tower.

[0067] Preferably, the solvent removal treatment in step (2) is carried out in a solvent removal tower.

[0068] Preferably, the separation in step (3) separates the intermediate product (light component) and the heavy component to achieve the removal of the heavy component; the devices for the separation exemplarily include but are not limited to: a short-path evaporator, a distillation tower.

[0069] Preferably, the operating pressure of the short-path evaporator is 0.05 - 4 kPa, for example, it can be 0.08 kPa, 0.1 kPa, 0.3 kPa, 0.5 kPa, 0.8 kPa, 1 kPa, 1.2 kPa, 1.5 kPa, 1.8 kPa, 2 kPa, 2.2 kPa, 2.5 kPa, 2.8 kPa, 3 kPa, 3.2 kPa, 3.5 kPa or 3.8 kPa, as well as specific point values between the above point values. Due to space limitations and for the sake of brevity, the specific point values included in the scope of the present invention are not exhaustively listed herein. More preferably, it is 0.1 - 2.5 kPa.

[0070] As a preferred technical solution of the present invention, the separated heavy components contain a large variety and relatively high content of chlorine-containing substances. By incorporating the separated heavy components into the separated intermediate product (light components) in a certain proportion to obtain a mixture, and then refining the mixture, the types and contents of chlorine-containing substances in the product can be effectively regulated, so that the effective factor of the isocyanate composition is 3.90 - 5.70.

[0071] Preferably, the mass percentage content of the heavy components (recovered heavy component materials) in the mixture is 1 - 10%, more preferably 2 - 10%, so that the effective factor of the isocyanate composition is 3.90 - 5.70. If the incorporation amount of the heavy components (recovered heavy component materials) is too small, the effective factor is too high, and when the isocyanate composition is used to prepare polyurethane / polythiourethane, adverse phenomena such as gelation are likely to occur; if the incorporation amount of the heavy components (recovered heavy component materials) is too high, the effective factor is low, and the isocyanate composition contains more impurities, which affects the color fastness (yellowing) performance and stability of polyurethane / polythiourethane, resulting in poor optical performance of the optical material.

[0072] Preferably, the heavy components mixed with the intermediate product can be directly incorporated back into the intermediate product, or can be obtained as recovered heavy component materials after being separated by a de-heavy component device through circulation and then incorporated into the intermediate product.

[0073] Preferably, the refining method is an industrial separation technology known in the art, exemplarily including but not limited to: distillation, rectification, crystallization, etc.

[0074] Preferably, the refining method is rectification.

[0075] Preferably, the rectification is carried out in a rectification column, and the rectification column preferably includes a plate rectification column or a packed rectification column.

[0076] Preferably, the number of theoretical plates of the rectification column is 2 - 60, for example, it can be 3, 5, 8, 10, 12, 15, 18, 20, 22, 25, 28, 30, 32, 35, 38, 40, 42, 45, 48, 52, 52, 55 or 58, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the above range. Further preferably, it is 5 - 40.

[0077] Preferably, the top pressure of the rectification column is 0.1 - 4 kPa, for example, it can be 0.2 kPa, 0.5 kPa, 0.8 kPa, 1 kPa, 1.2 kPa, 1.5 kPa, 1.8 kPa, 2 kPa, 2.2 kPa, 2.5 kPa, 2.8 kPa, 3 kPa, 3.2 kPa, 3.5 kPa or 3.8 kPa, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the above range. Further preferably, it is 0.15 - 2.5 kPa.

[0078] Preferably, the top reflux ratio of the rectification column is 0.01 - 60, for example, it can be 0.05, 0.1, 0.5, 1, 3, 5, 8, 10, 12, 15, 18, 20, 22, 25, 28, 30, 32, 35, 38, 40, 42, 45, 48, 50, 52, 55 or 58, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the above range. Further preferably, it is 0.1 - 40.

[0079] In a preferred technical solution of the present invention, the preparation method of the isocyanate composition includes the following steps:

[0080] (1a) Salt - formation step: The diamine reacts with hydrogen chloride to form a diamine hydrochloride.

[0081] (1) Phosgenation step: The diamine hydrochloride obtained in step (1) reacts with phosgene to obtain a reaction product.

[0082] (2) Removal step: The reaction product obtained in step (1) is subjected to a removal treatment to obtain a crude product; the removal treatment includes phosgene removal treatment and / or solvent removal treatment.

[0083] (3a) Separation step: The crude product obtained in step (2) is separated to obtain a heavy fraction and an intermediate product (light fraction).

[0084] (3b) Heavy component recovery process: Mix the intermediate product obtained in step (3a) with the heavy components to obtain a mixture; the mass percentage of the heavy components in the mixture is 1-10%; or, perform secondary separation on the heavy components obtained in step (3a) to obtain a heavy component recovery material and residual heavy components; mix the heavy component recovery material with the intermediate product to obtain a mixture; the mass percentage of the heavy component recovery material in the mixture is 1-10%.

[0085] (3c) Refining process: Refine the mixture obtained in step (3b) to obtain the isocyanate composition.

[0086] Exemplarily, the process flow diagram of the preparation method is as Figure 1 shown, including a salification process 10, a phosgenation process 20, a removal process 30, a separation process 40, a heavy component recovery process 50, and a refining process 60. Among them, the salification process and the phosgenation process can be implemented in an intermittent or continuous manner, and the continuous manner is carried out continuously through a kettle. By appropriately adjusting the mixing ratio of the heavy components and the intermediate product, the supply ratio of phosgene, the reaction temperature, the reaction pressure, the average residence time, the reflux ratio of the distillation column, etc., the effective factor of the isocyanate composition is adjusted, and the control of the effective factor is mainly achieved through the ratio of the heavy components to the intermediate product.

[0087] Specifically, taking the XDI composition as an example, its preparation method is as follows:

[0088] (1a) Salification process: A kettle reaction can be used, either a single kettle or two kettles; first, load the reaction solvent into the salification kettle; then, add hydrogen chloride and xylylenediamine (XDA) to the salification kettle in the above-mentioned ratio of hydrogen chloride and diamine; while maintaining the inside of the salification kettle at the above-mentioned salification temperature and pressure, stir and mix the hydrogen chloride and amine solution through the stirring blade to obtain XDA hydrochloride; while continuously supplying hydrogen chloride gas and amine solution to the salification kettle, continuously take out the slurry containing XDA hydrochloride from the salification kettle and transport it to the phosgenation process.

[0089] (1) Phosgenation process: A kettle reaction is used, three or four kettles in series. Continuously transport the above-mentioned XDA hydrochloride to the phosgenation reaction kettle, and continuously introduce phosgene into the tops of the first phosgenation kettle, the second phosgenation kettle, and the third phosgenation kettle in the above-mentioned supply ratio through insertion pipes; then, while maintaining the inside of the phosgenation kettle at the above-mentioned reaction temperature and reaction pressure, stir and mix the slurry and phosgene. Thus, XDA hydrochloride reacts with phosgene to generate XDI as the main component and CBI and other intermediates as by-products to obtain a reaction solution.

[0090] Thus, the salification process and the phosgenation process are continuously implemented.

[0091] (2) Removal process: It is carried out using a degassing tower and a solvent removal tower. The above reaction liquid is continuously fed to the middle part of the degassing tower. Through the degassing tower, phosgene, hydrogen chloride, etc. are removed from the reaction liquid; then, through the solvent removal tower, the solvent in the reaction liquid is removed to obtain crude XDI.

[0092] (3a) Separation process: The above crude XDI is separated using a short-path evaporator to remove heavy components, obtaining an intermediate product and a primary heavy component.

[0093] (3b) Heavy component recovery process: The primary heavy component is recovered through a short-path evaporator to obtain a heavy component recovery material and a secondary heavy component, which can be recovered once or cyclically; the mixture obtained by mixing the heavy component recovery material with the intermediate product enters the refining process; the mass percentage content of the heavy component recovery material in the mixture is 1 - 10%.

[0094] (3c) Refining process: The above mixture is continuously fed to the middle part of the distillation column; then, under the conditions of the aforementioned distillation (bottom temperature, top temperature, top pressure, bottom reflux ratio, top reflux ratio, residence time), the low-boiling components are distilled off from the intermediate product, and the XDI composition is withdrawn from a position slightly below the middle of the column.

[0095] Thus, an XDI composition including XDI, CBI, and substances corresponding to the effective factors can be continuously manufactured.

[0096] In a third aspect, the present invention provides a modified isocyanate, which is obtained by modifying the isocyanate composition as described in the first aspect; the modified isocyanate contains any one or a combination of at least two of the groups (a)-(i): (a) isocyanurate group, (b) uretdione group, (c) biuret group, (d) urethane group, (e) urea group, (f) iminooxadiazinedione group, (g) urethane-formate group, (h) uretonimine group, (i) carbodiimide group.

[0097] Those skilled in the art can modify the aforementioned isocyanate composition according to needs using known methods to obtain the modified isocyanate; the modified isocyanate is suitably used as a polyisocyanate component and a substance containing an active hydrogen group as a raw material for polyurethane resins and polythiourethane resins.

[0098] Specifically, the modified isocyanate containing the group (a) isocyanurate group is a trimer of isocyanate. Exemplarily, it can be obtained by reacting the isocyanate composition in the presence of a known isocyanuration catalyst to carry out isocyanuration of the isocyanate therein.

[0099] The modified isocyanate containing the group (b) uretdione group can be obtained by heating the isocyanate composition at about 90 - 200 °C, or by reacting it in the presence of a known uretdionization catalyst to cause uretdionization (e.g., dimerization) of the isocyanate.

[0100] The modified isocyanate containing the group (c) biuret group can be obtained by reacting the isocyanate composition with, for example, water, a tertiary alcohol (e.g., tert-butanol, etc.), a secondary amine (e.g., dimethylamine, diethylamine, etc.), etc., and then further reacting it in the presence of a known biuretization catalyst.

[0101] The modified isocyanate containing the group (d) carbamate group can be obtained by reacting the isocyanate composition with a polyol component (e.g., trimethylolpropane, etc.).

[0102] The modified isocyanate containing the group (e) urea group can be obtained by reacting the isocyanate composition with water, a polyamine component (described later), etc.

[0103] The modified isocyanate containing the group (f) iminooxadiazinedione group is an asymmetric trimer of the isocyanate and can be obtained by reacting the isocyanate composition in the presence of a known iminooxadiazinedionization catalyst to cause iminooxadiazinedionization (e.g., trimerization) of the isocyanate.

[0104] The modified isocyanate containing the group (g) urethane group can be obtained by reacting the isocyanate composition with an alcohol and then further reacting it in the presence of a known urethanization catalyst.

[0105] The modified isocyanate containing the group (h) uretonimine group can be obtained by reacting the isocyanate composition in the presence of a known carbodiimidization catalyst to form a carbodiimide group and then adding an isocyanate to the carbodiimide group.

[0106] The modified isocyanate containing the group (i) carbodiimide group can be obtained by reacting the isocyanate composition in the presence of a known carbodiimidization catalyst.

[0107] It should be noted that the modified isocyanate only needs to contain at least one of the above groups (a) - (i), and it can also contain at least two. Such a modified isocyanate can be generated by appropriately combining the above reactions. In addition, the modified isocyanate can be used alone or in combination of two or more.

[0108] Fourth aspect, the present invention provides a polyurethane resin, which is formed by reacting an isocyanate-based substance with a substance containing an active hydrogen group; the isocyanate-based substance includes at least one of the isocyanate composition as described in the first aspect and the modified isocyanate as described in the third aspect.

[0109] Preferably, the active hydrogen group includes any one or a combination of at least two of hydroxyl group, amino group, and mercapto group.

[0110] Preferably, the substance containing an active hydrogen group includes any one or a combination of at least two of polyols, polyamines, and polythiols.

[0111] Fifth aspect, the present invention provides an optical material, which is formed by polymerizing an isocyanate-based substance with a polythiol compound; the isocyanate-based substance includes at least one of the isocyanate composition as described in the first aspect and the modified isocyanate as described in the third aspect.

[0112] In the present invention, the optical material is polythiourethane; the polythiol compound refers to a compound containing at least two thiol groups (mercapto groups).

[0113] Preferably, the optical material is applied to lenses, lenses, prisms, lamp shade materials, transparent packaging materials, transparent building materials, or electronic products; specifically, the optical material is applied to lenses, plastic lenses, prisms, automotive lamp shade materials, transparent roof materials, lens materials for electronic devices (mobile phones or tablet computers), etc.

[0114] Preferably, the polythiol compound includes aliphatic polythiol compounds such as methanedithiol, 1,2-ethanedithiol, 1,1-propanedithiol, 1,2-propanedithiol, 1,3-propanedithiol, 2,2-propanedithiol, 1,6-hexanedithiol, 1,2,3-propanetrithiol, 1,1-cyclohexanedithiol, 1,2-cyclohexanedithiol, 2,2-dimethylpropane-1,3-dithiol, 3,4-dimethoxybutane-1,2-dithiol, 2-methylcyclohexane-2,3-dithiol, 1,1-bis(mercaptomethyl)cyclohexane, bis(2-mercaptoethyl) thiodipropionate, 2,3-dimercapto-1-propanol (2-mercaptoacetate), 2,3-dimercapto-1-propanol (3-mercaptopropionate), diethylene glycol bis(2-mercaptoacetate), diethylene glycol bis(3-mercaptopropionate), 1,2-dimercaptopropyl methyl ether, 2,3-dimercaptopropyl methyl ether, 2,2-bis(mercaptomethyl)-1,3-propanedithiol, bis(2-mercaptoethyl) ether, ethylene glycol bis(2-mercaptoacetate), ethylene glycol bis(3-mercaptopropionate), trimethylolpropane bis(2-mercaptoacetate), trimethylolpropane bis(3-mercaptopropionate), pentaerythritol tetra(2-mercaptoacetate), pentaerythritol tetra(3-mercaptopropionate), tetrakis(mercaptomethyl)methane, etc.

[0115] Preferably, the polythiol compound further includes aromatic polythiol compounds such as 1,2-benzenedithiol, 1,3-benzenedithiol, 1,4-benzenedithiol, 1,2-bis(mercaptomethyl)benzene, 1,3-bis(mercaptomethyl)benzene, 1,4-bis(mercaptomethyl)benzene, 1,2-bis(mercaptoethyl)benzene, 1,3-bis(mercaptoethyl)benzene, 1,4-bis(mercaptoethyl)benzene, 1,2,3-benzenetrithiol, 1,2,4-benzenetrithiol, 1,3,5-benzenetrithiol, 1,2,3-tris(mercaptomethyl)benzene, 1,2,4-tris(mercaptomethyl)benzene, 1,3,5-tris(mercaptomethyl)benzene, 1,2,3-tris(mercaptoethyl)benzene, 1,2,4-tris(mercaptoethyl)benzene, 1,3,5-tris(mercaptoethyl)benzene, 2,5-toluenedithiol, 3,4-toluenedithiol, 1,3-bis(p-methoxyphenyl)propane-2,2-dithiol, 1,3-diphenylpropane-2,2-dithiol, phenylmethane-1,1-dithiol, 2,4-bis(p-mercaptophenyl)pentane, etc.

[0116] Preferably, the polythiol compound further includes aromatic polythiol compounds containing sulfur atoms other than mercapto groups, such as 1,2-bis(mercaptoethylthio)benzene, 1,3-bis(mercaptoethylthio)benzene, 1,4-bis(mercaptoethylthio)benzene, 1,2,3-tris(mercaptomethylthio)benzene, 1,2,4-tris(mercaptomethylthio)benzene, 1,3,5-tris(mercaptomethylthio)benzene, 1,2,3-tris(mercaptoethylthio)benzene, 1,2,4-tris(mercaptoethylthio)benzene, 1,3,5-tris(mercaptoethylthio)benzene, and their alkylated products, etc.

[0117] Preferably, the polythiol compound further includes aliphatic polythiol compounds containing sulfur atoms other than mercapto groups, such as bis(mercaptomethyl)sulfide, bis(mercaptomethyl) disulfide, bis(mercaptoethyl)sulfide, bis(mercaptoethyl) disulfide, bis(mercaptopropyl)sulfide, bis(mercaptomethylthio)methane, bis(2-mercaptoethylthio)methane, bis(3-mercaptopropylthio)methane, 1,2-bis(mercaptomethylthio)ethane, 1,2-bis(2-mercaptoethylthio)ethane, 1,2-bis(3-mercaptopropyl)ethane, 1,3-bis(mercaptomethylthio)propane, 1,3-bis(2-mercaptoethylthio)propane, 1,3-bis(3-mercaptopropylthio)propane, 1,2,3-tris(mercaptomethylthio)propane, 1,2,3-tris(2-mercaptoethylthio)propane, 1,2,3-tris(3-mercaptopropylthio)propane, 1,2-bis((2-mercaptoethyl)thio)-3-mercaptopropane, 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 5,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, bis(mercaptomethyl)-3,6,9-trithia-1,11-undecanedithiol, tetrakis(mercaptomethylthiomethyl)methane, tetrakis(2-mercaptoethylthiomethyl)methane, tetrakis(3-mercaptopropylthiomethyl)methane, bis(2,3-dimercaptopropyl)sulfide, bis(1,3-dimercaptopropyl)sulfide, 2,5-dimercapto-1,4-dithiane, 2,5-dimercaptomethyl-1,4-dithiane, 2,5-dimercaptomethyl-2,5-dimethyl-1,4-dithiane, bis(mercaptomethyl) disulfide, bis(mercaptoethyl) disulfide, bis(mercaptopropyl) disulfide, and their esters of mercaptoacetic acid and mercaptopropionic acid.

[0118] Preferably, the polythiol compound further includes other aliphatic polythiol compounds containing sulfur atoms and ester bonds other than mercapto groups, such as hydroxymethyl thioether bis(2-mercaptoacetate), hydroxymethyl thioether bis(3-mercaptopropionate), hydroxyethyl thioether bis(2-mercaptoacetate), hydroxyethyl thioether bis(3-mercaptopropionate), hydroxypropyl thioether bis(2-mercaptoacetate), hydroxypropyl thioether bis(3-mercaptopropionate), hydroxymethyl disulfide bis(2-mercaptoacetate), hydroxymethyl disulfide bis(3-mercaptopropionate), hydroxyethyl disulfide bis(2-mercaptoacetate), hydroxyethyl disulfide bis(3-mercaptopropionate), hydroxypropyl disulfide bis(2-mercaptoacetate), hydroxypropyl disulfide bis(3-mercaptopropionate), 2-mercaptoethyl ether bis(2-mercaptoacetate), 2-mercaptoethyl ether bis(3-mercaptopropionate), 1,4-dithiane-2,5-diol bis(2-mercaptoacetate), 1,4-dithiane-2,5-diol bis(3-mercaptopropionate), sulfinyl diacetic acid bis(2-mercaptoacetate), thiodipropionic acid bis(2-mercaptoacetate), 4,4-thiodibutyric acid bis(2-mercaptoacetate), sulfonyl diacetic acid bis(2-mercaptoacetate), dithiodipropionic acid bis(2-mercaptoacetate), 4,4-dithiodibutyric acid bis(2-mercaptoacetate), sulfinyl diacetic acid bis(2,3-dimercaptopropyl ester), thiodipropionic acid bis(2,3-dimercaptopropyl ester), sulfonyl diacetic acid bis(2,3-dimercaptopropyl ester), dithiodipropionic acid bis(2,3-dimercaptopropyl ester).

[0119] Preferably, the polythiol compound further includes heterocyclic compounds containing sulfur atoms other than mercapto groups, such as 3,4-thiophenedithiol, 2,5-dimercapto-1,3,4-thiadiazole.

[0120] Preferably, the polythiol compound further includes compounds containing hydroxyl groups other than mercapto groups, such as 2-mercaptoethanol, 3-mercapto-1,2-propanediol, glycerol bis(mercaptoacetate), 1-hydroxy-4-mercaptocyclohexane, 2,4-dimercaptophenol, 2-mercaptohydroquinone, 4-mercaptophenol, 3,4-dimercapto-2-propanol, 1,3-dimercapto-2-propanol, 2,3-dimercapto-1-propanol, 1,2-dimercapto-1,3-butanediol, pentaerythritol tris(3-mercaptopropionate), pentaerythritol mono(3-mercaptopropionate), pentaerythritol bis(3-mercaptopropionate), pentaerythritol tris(mercaptoacetate), dipentaerythritol penta(3-mercaptopropionate), hydroxymethyl-tris(mercaptoethylthiomethyl)methane, 1-hydroxyethylthio-3-mercaptoethylthiobenzene.

[0121] Preferably, the polythiol compound further includes 1,1,3,3 - tetrakis(mercaptomethylthio)propane, 1,1,2,2 - tetrakis(mercaptomethylthio)ethane, 4,6 - bis(mercaptomethylthio)-1,3 - dithiane, 1,1,5,5 - tetrakis(mercaptomethylthio)-3 - thiapentane, 1,1,6,6 - tetrakis(mercaptomethylthio)-3,4 - dithiahexane, 2,2 - bis(mercaptomethylthio)ethanethiol, 2-(4,5 - dimercapto - 2 - thiapentyl)-1,3 - dithiacyclopentane, 2,2 - bis(mercaptomethyl)-1,3 - dithiacyclopentane, 2,5 - bis(4,4 - bis(mercaptomethylthio)-2 - thiabutyl)-1,4 - dithiane, 2,2 - bis(mercaptomethylthio)-1,3 - propanedithiol, 3 - mercaptomethylthio - 1,7 - dimercapto - 2,6 - dithiaheptane, 3,6 - bis(mercaptomethylthio)-1,9 - dimercapto - 2,5,8 - trithianonane, 4,6 - bis(mercaptomethylthio)-1,9 - dimercapto - 2,5,8 - trithianonane, 3 - mercaptomethylthio - 1,6 - dimercapto - 2,5 - dithiahexane, 2-(2,2 - bis(mercaptomethylthio)ethyl)-1,3 - dithiacyclobutane, 1,1,9,9 - tetrakis(mercaptomethylthio)-5-(3,3 - bis(mercaptomethylthio)-1 - thiapropyl)3,7 - dithianonane, tris(2,2 - bis(mercaptomethylthio)ethyl)methane, tris(4,4 - bis(mercaptomethylthio)-2 - thiabutyl)methane, tetrakis(2,2 - bis(mercaptomethylthio)ethyl)methane, tetrakis(4,4 - bis(mercaptomethylthio)-2 - thiabutyl)methane, 3,5,9,11 - tetrakis(mercaptomethylthio)-1,13 - dimercapto - 2,6,8,12 - tetrathiatridecane, 3,5,9,11,15,17 - hexakis(mercaptomethylthio)-1,19 - dimercapto - 2,6,8,12,14,18 - hexathianonadecane, 9-(2,2 - bis(mercaptomethylthio)ethyl)-3,5,13,15 - tetrakis(mercaptomethylthio)-1,17 - dimercapto - 2,6,8,10,12,16 - hexathiaheptadecane, 3,4,8,9 - tetrakis(mercaptomethylthio)-1,11 - dimercapto - 2,5,7,10 - tetrathiaundecane, 3,4,8,9,13,14 - hexakis(mercaptomethylthio)-1,16 - dimercapto - 2,5,7,10,12,15 - hexathiahexadecane, 8-(bis(mercaptomethylthio)methyl)-3,4,12,13 - tetrakis(mercaptomethylthio)1,15 - dimercapto - 2,5,7,9,11,14 - hexathiapentadecane, 4,6 - bis(3,5 - bis(mercaptomethylthio)-7 - mercapto - 2,6 - dithiaheptylthio)-1,3 - dithiane, 4-(3,5 - bis(mercaptomethylthio)-7 - mercapto - 2,6 - dithiaheptylthio)-6 - mercaptomethylthio - 1,3 - dithiane, 1,1 - bis(4-(6 - mercaptomethylthio)-1,3 - dithianylthio)-3,3-bis(mercaptomethylthio)propane, 1,3-bis(4-(6-mercaptomethylthio)-1,3-dithianylthio)-1,3-bis(mercaptomethylthio)propane, 1-(4-(6-mercaptomethylthio)-1,3-dithianylthio)-3-(2,2-bis(mercaptomethylthio)ethyl)-7,9-bis(mercaptomethylthio)-2,4,6,10-tetrathiaundecane, 1-(4-(6-mercaptomethylthio)-1,3-dithianylthio)-3-(2-(1,3-dithietanyl))methyl-7,9-bis(mercaptomethylthio)-2,4,6,10-tetrathiaundecane, 1,5-bis(4-(6-mercaptomethylthio)-1,3-dithianylthio)-3-(2-(1,3-dithietanyl))methyl-2,4-dithiapentane, 4,6-bis(3-(2-(1,3-dithietanyl))methyl-5-mercapto-2,4-dithiapentylthio)-1,3-dithiane, 4,6-bis(4-(6-mercaptomethylthio)-1,3-dithianylthio)-1,3-dithiane, 4-(4-(6-mercaptomethylthio)-1,3-dithianylthio)-6-(4-(6-mercaptomethylthio)-1,3-dithianylthio)-1,3-dithiane, 3-(2-(1,3-dithietanyl))methyl-7,9-bis(mercaptomethylthio)-1,11-dimercapto-2,4,6,10-tetrathiaundecane, 9-(2-(1,3-dithietanyl))methyl-3,5,13,15-tetrakis(mercaptomethylthio)-1,17-dimercapto-2,6,8,10,12,16-hexathiaheptadecane, 3-(2-(1,3-dithietanyl))methyl-7,9,13,15-tetrakis(mercaptomethylthio)-1,17-dimercapto-2,4,6,10,12,16-hexathiaheptadecane, 3,7-bis(2-(1,3-dithietanyl))methyl-1,9-dimercapto-2,4,6,8-tetrathianonane, 4-(3,4,8,9-tetrakis(mercaptomethylthio)-11-mercapto-2,5,7,10-tetrathiaundecyl)-5-mercaptomethylthio-1,3-dithiacyclopentane, 4,5-bis(3,4-bis(mercaptomethylthio)-6-mercapto-2,5-dithiahexylthio)-1,3-dithiacyclopentane, 4-(3,4-bis(mercaptomethylthio)-6-mercapto-2,5-dithiahexylthio)-5-mercaptomethylthio-1,3-dithiacyclopentane, 4-(3-bis(mercaptomethylthio)methyl-5,6-bis(mercaptomethylthio)-8-mercapto-2,4,7-trithiaoctyl)-5-mercaptomethylthio-1,3-dithiacyclopentane, 2-(bis(3,4-bis(mercaptomethylthio)-6-mercapto-2,5-dithiahexylthio)methyl)-1,3-dithietane, 2-(3,4-bis(mercaptomethylthio)-6-mercapto-2,5-dithiahexylthio)mercaptomethylthio methyl-1,3-dithietane, 2-(3,4,8,9-tetrakis(mercaptomethylthio)-11-mercapto-2,5,7,10-tetrathiaundecylthio)mercaptomethyl-1,3-dithietane, 2-(3-bis(mercaptomethylthio)methyl-5,6-bis(mercaptomethylthio)-8-mercapto-2,4,7-trithiaoctyl)mercaptomethyl-1,3-dithietane, 4,5-bis(1-(2-(1,3-dithietanyl))-3-mercapto-2-thiapropylthio)-1,3-dithiolane, 4-(1-(2-(1,3-dithietanyl))-3-mercapto-2-thiapropylthio)-5-(1,2-bis(mercaptomethylthio)-4-mercapto-3-thiabutylthio)-1,3-dithiolane, 2-(bis(4-(5-mercaptomethylthio-1,3-dithiolanyl)thio))methyl-1,3-dithietane, 4-(4-(5-mercaptomethylthio-1,3-dithiolanyl)thio)-5-(1-(2-(1,3-dithietanyl))-3-mercapto-2-thiapropylthio)-1,3-dithiolane, and compounds having a dithioacetal or dithioketal skeleton such as their oligomers.,

[0122] Preferably, the polythiol compound further includes tris(mercaptomethylthio)methane, tris(mercaptoethylthio)methane, 1,1,5,5-tetrakis(mercaptomethylthio)-2,4-dithiapentane, bis(4,4-bis(mercaptomethylthio)-1,3-dithiabutyl)(mercaptomethylthio)methane, tris(4,4-bis(mercaptomethylthio)-1,3-dithiabutyl)methane, 2,4,6-tris(mercaptomethylthio)-1,3,5-trithiacyclohexane, 2,4-bis(mercaptomethylthio)-1,3,5-trithiacyclohexane, 1,1,3,3-tetrakis(mercaptomethylthio)-2-thiapropane, bis(mercaptomethyl)methylthio-1,3,5-trithiacyclohexane, tris(((4-mercaptomethyl-2,5-dithiahexyl-1-yl)methylthio)methane, 2,4-bis(mercaptomethylthio)-1,3-dithiolane, 2-mercaptoethylthio-4-mercaptomethyl-1,3-dithiolane, 2-(2,3-dimercaptopropylthio)-1,3-dithiolane, 4-mercaptomethyl-2-(2,3-dimercaptopropylthio)-1,3-dithiolane, 4-mercaptomethyl-2-(1,3-dimercapto-2-propylthio)-1,3-dithiolane, tris(2,2-bis(mercaptomethylthio)-1-thiaethyl)methane, tris(3,3-bis(mercaptomethylthio)-2-thiapropyl)methane, tris(4,4-bis(mercaptomethylthio)-3-thiabutyl)methane, 2,4,6-tris(3,3-bis(mercaptomethylthio)-2-thiapropyl)-1,3,5-trithiacyclohexane, tetrakis(3,3-bis(mercaptomethylthio)-2-thiapropyl)methane, and the like, and compounds having a trithiocarbonate skeleton such as their oligomers.

[0123] Preferably, the polythiol compound further includes 3,3'-bis(mercaptomethylthio)-1,5-dimercapto-2,4-dithiapentane, 2,2'-bis(mercaptomethylthio)-1,3-dithiolane, 2,7-bis(mercaptomethyl)-1,4,5,9-tetrathiaspiro[4.4]nonane, 3,9-dimercapto-1,5,7,11-tetrathiaspiro[5.5]undecane, and compounds having a tetrathiocarbonate skeleton such as their oligomers.

[0124] It should be noted that the polythiol compound is not limited to the compounds listed above. In addition, the compounds listed above can be used alone or in combination of at least two kinds.

[0125] Preferably, the polythiol compound includes at least one of 1,2-bis((2-mercaptoethyl)thio)-3-mercaptopropane, bis(mercaptomethyl)-3,6,9-trithia-1,11-undecanedithiol, pentaerythritol tetra(3-mercaptopropionate), 1,1,3,3-tetrakis(mercaptomethylthio)propane, or 2-mercaptoethanol.

[0126] Preferably, in the preparation of the optical material, the polymerization is carried out in the presence of a polymerization catalyst, and the polymerization catalyst is preferably an organotin compound, exemplarily including but not limited to: dialkyltin halides such as dibutyltin dichloride and dimethyltin dichloride; dialkyltin dicarboxylates such as dimethyltin diacetate, dibutyltin dioctanoate, and dibutyltin dilaurate.

[0127] In addition, according to the purpose, the raw materials for the preparation of the optical material further optionally include auxiliaries, which exemplarily include but not limited to: any one or a combination of at least two of chain extenders, crosslinking agents, light stabilizers, ultraviolet absorbers, antioxidants, oil-soluble dyes, fillers, and mold release agents.

[0128] Preferably, the optical material formed from a polythiourethane resin is usually manufactured by injection polymerization. Specifically, a polythiol compound and an isocyanate are mixed, and optionally a suitable auxiliary is added. When necessary, this mixture (polymerizable composition) is degassed by an appropriate method and then injected into an injection mold for an optical material, and it is usually slowly heated from a low temperature to a high temperature to polymerize. Then, the optical material is obtained by demolding.

[0129] Preferably, the temperature of the polymerization is 80 - 200 °C, for example, it can be 90 °C, 100 °C, 110 °C, 120 °C, 130 °C, 140 °C, 150 °C, 160 °C, 170 °C, 180 °C, 190 °C, etc.

[0130] Preferably, the time of the polymerization is 1 - 24 h, for example, it can be 2 h, 4 h, 6 h, 8 h, 10 h, 11 h, 12 h, 14 h, 16 h, 18 h, 20 h, 22 h, or 23 h, etc.

[0131] As a preferred technical solution of the present invention, the isocyanate composition is used for the preparation of the optical material polythiourethane, which can endow the optical material with excellent transparency, color stability, and yellowing resistance, and significantly reduce the incidence of optical deformation of the optical material (≤1%, 0 - 1%); specifically, the yellowness index YI of the optical material prepared with the XDI composition is ≤1.60, and the YI of the optical material prepared with the H6XDI composition and the NBDI composition is ≤1.50.

[0132] As a preferred technical solution of the present invention, the transmittance of the optical material (polythiourethane) prepared with the XDI composition is 83.95 - 84.10%, the transmittance of the optical material (polythiourethane) prepared with the H6XDI composition is ≥86.0%, and the transmittance of the optical material (polythiourethane) prepared with the NBDI composition is 85.89 - 86.85%.

[0133] As a preferred technical solution of the present invention, the glass transition temperature (Tg) of the optical material (polythiourethane) prepared from the XDI composition is 84.56 - 85.67 °C, the glass transition temperature of the optical material (polythiourethane) prepared from the H6XDI composition is 89.08 - 89.67 °C, and the glass transition temperature of the optical material (polythiourethane) prepared from the NBDI composition is 108.08 - 108.65 °C.

[0134] Compared with the prior art, the present invention has the following beneficial effects:

[0135] In the isocyanate composition provided by the present invention, through the design and control of the effective factors, it has excellent reaction activity and can be used for the preparation of high-performance polyurethane, polythiourethane and other resins, and no adverse phenomena such as gel will occur during the polymerization process. Moreover, the isocyanate composition can effectively improve the yellowing resistance, stability and optical properties of products such as polyurethane and polythiourethane, so that the obtained polyurethane and polythiourethane will not show turbidity and opacity. The optical material prepared from the isocyanate composition has a high glass transition temperature, good heat resistance, a significantly reduced yellowness index and a significantly reduced incidence of optical deformation, and a high transmittance, thereby effectively improving the optical properties of the optical material. Description of the Drawings

[0136] Figure 1 It is a process flow diagram of the preparation method of the isocyanate composition in a specific embodiment of the present invention;

[0137] Among them, 10 - salification process, 20 - phosgenation process, 30 - removal process, 40 - separation process, 50 - heavy component recovery process, 60 - refining process. Specific Embodiments

[0138] The technical solution of the present invention will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations to the present invention.

[0139] The test methods for the components and properties in the present invention are as follows:

[0140] 1. Determination of the mass content (A value) of chlorine in the isocyanate composition: XRF test

[0141] Instrument: Energy dispersive X-ray fluorescence spectrometer (ED-XRF), model: MERAK-LE II;

[0142] Method: Standard addition method

[0143] Principle and operation: Chromatographically pure CCl 4The standard sample is a Cl source, and ethyl acetate is the diluent. X-rays generated by an X-ray tube are used to excite the Cl element in the sample, generating characteristic X-ray fluorescence. The intensity of the characteristic X-ray fluorescence has a linear relationship with the element concentration. A standard curve is plotted, and the extrapolated value is the content of the Cl element in the sample.

[0144] 2. Determination of the mass content (B value) of chloro-isocyanate in the isocyanate composition: GCMS test

[0145] Analysis is carried out using gas chromatography-mass spectrometry under the following conditions. The content in this article is the normalized content.

[0146] Analysis instrument: Agilent 5977B GCMS

[0147] Chromatographic column: DB-5 chromatographic column, with specifications of 30m×0.25mm×0.25μm

[0148] Column oven temperature: Maintain at 50°C for 2 min, increase the temperature to 80°C at a rate of 5°C / min, then increase the temperature to 280°C at a rate of 15°C / min, and maintain for 10 min

[0149] Split ratio: Splitless

[0150] Injector temperature: 280°C

[0151] Detection temperature: 300°C

[0152] Carrier gas: Helium

[0153] Carrier gas flow rate: 1 mL / min (constant flow rate)

[0154] Injection volume: 1 μL

[0155] Detection method: SIM selective ion scanning mode (selective ions for XDI are 160 / 126, selective ions for H6XDI are 186 / 152, and selective ions for NBDI are 198 / 164)

[0156] 3. Determination of the mass percentage content of isocyanate in the isocyanate composition: Gas chromatography test

[0157] Analysis is carried out using gas chromatography under the following conditions. The content in this article is the normalized content.

[0158] Analysis instrument: Agilent 7890B GC

[0159] Chromatographic column: DB-5 chromatographic column, with specifications of 30m×0.25mm×0.25μm

[0160] Column oven temperature: Maintain at 60°C for 1 min, increase the temperature to 300°C at a rate of 10°C / min, and maintain for 5 min

[0161] Separation ratio: 30:1

[0162] Inlet temperature: 280 °C

[0163] Detection temperature: 320 °C

[0164] Carrier gas: Nitrogen

[0165] Carrier gas flow rate: 1 mL / min (constant flow rate)

[0166] Sample injection volume: 1 μL

[0167] Detector: FID

[0168] In the following specific embodiments of the present invention, unless otherwise specified, "parts" and "%" are based on mass.

[0169] Example 1

[0170] An XDI composition and its preparation method, the effective factor E of the XDI composition is 4.70, and the process flow diagram of its preparation method is as Figure 1 shown, specifically including the following steps:

[0171] Salting process: Charge 800 parts by mass of chlorobenzene into a salting kettle, adjust the salting temperature in the salting kettle to 25 °C, and adjust the salting pressure (gauge pressure) in the salting kettle to 0.04 MPa G. Continuously blow HCl gas into the salting kettle at a rate of 85.8 parts by mass / h, and continuously charge an amine solution of 1,3-XDA (1,3-benzenedimethanamine) (the mass concentration of 1,3-XDA is 8.0 wt.%, and the solvent is chlorobenzene) into the salting kettle at a rate of 1000 parts by mass / h, so that the molar ratio of HCl to 1,3-XDA is 4:1, thereby generating a slurry containing 1,3-XDA hydrochloride, and conveying the slurry containing 1,3-XDA hydrochloride to a phosgenation kettle.

[0172] Phosgenation process: Convey the slurry containing 1,3-XDA hydrochloride to the phosgenation kettle, continuously introduce phosgene into the phosgenation kettle at a rate of 581.5 parts by mass / h, the reaction temperature in the kettle is 145 °C, the reaction pressure (gauge pressure) is 0.2 MPa G, the molar ratio of phosgene to 1,3-XDA hydrochloride is 10:1, and the residence time is 7 h. Thus, 1,3-XDA hydrochloride reacts with phosgene to generate 1,3-XDI, and a reaction product containing 1,3-XDI is obtained.

[0173] Removal process: Continuously convey the reaction product obtained in the phosgenation process to a degassing tower and a desolventizing tower, and perform degassing treatment and desolventizing treatment respectively. Thus, 108 parts by mass of crude 1,3-XDI are prepared.

[0174] Separation process: The crude product is continuously fed to a short-path evaporator (heavy component separator) to obtain an intermediate product of 99.7 mass parts with heavy components removed and a primary heavy component of 6.3 mass parts.

[0175] Heavy component recovery process: The primary heavy component is continuously fed to a secondary short-path evaporator to obtain a heavy component recovery material of 2.03 mass parts and a residual heavy component of 4.27 mass parts. The intermediate product at a rate of 99.7 mass parts / h is mixed with the heavy component recovery material at a rate of 2.03 mass parts / h to obtain a mixture, that is, the mass percentage content of the heavy component recovery material in the mixture is 2%.

[0176] Refining process: The aforementioned mixture is continuously fed into a distillation column. For the distillation column, it is filled with packing equivalent to 25 theoretical plates. Then, in the distillation column, light components are removed from the top of the column, and an XDI composition is withdrawn from the middle of the column to obtain the target product;

[0177] The distillation conditions in the distillation column are as follows:

[0178] Bottom temperature: 145 - 150 °C

[0179] Top temperature: 100 - 120 °C

[0180] Top pressure: 0 - 50 PaA

[0181] Residence time: 2 - 4 h

[0182] Top reflux ratio: 10

[0183] Withdrawal amount in the distillation process: 96.2 mass parts / h.

[0184] Thus, the XDI composition is obtained, in which the mass content of 1,3-XDI > 99%, the mass content of chlorine (A value) is 108 ppm, the mass content of CBI (B value) is 450 ppm, and the effective factor E is 4.70.

[0185] Examples 2 - 5, Comparative Examples 1 - 2

[0186] An XDI composition and its preparation method, the effective factor E of the XDI composition is shown in Table 1 respectively, and the process flow of its preparation method is the same as that of Example 1, except that some process parameters are different, which are specifically shown in Table 1 (the processes / parameters not shown in Table 1 are exactly the same as those in Example 1). In Table 1, "HCl ratio" represents the molar amount of HCl based on 1 mol of 1,3-XDA in the salification process; "phosgene ratio" represents the molar amount of phosgene based on 1 mol of 1,3-XDA hydrochloride in the phosgenation process; "heavy component recovery material ratio" represents the mass percentage content of the heavy component (recovery material) in the mixture in the heavy component recovery process.

[0187] Table 1

[0188]

[0189]

[0190] Examples 6 - 10, Comparative Examples 3 - 4

[0191] An H6XDI composition and its preparation method. The effective factor E of the H6XDI composition is shown in Table 2 respectively. The process flow of its preparation method is the same as that of Example 1, except that 1,3 - XDA in the salification process is replaced by 1,3 - H6XDA, and the feed rate remains the same, both being 1000 parts by mass / h of an amine solution of 1,3 - H6XDA (1,3 - cyclohexanedimethylamine) (mass concentration is 8.0 wt.%, and the solvent is chlorobenzene). There are some process parameters different, which are specifically shown in Table 2 (the processes / parameters not shown in Table 2 are exactly the same as those in Example 1). In Table 2, "HCl ratio" represents the molar amount of HCl based on 1 mol of 1,3 - H6XDA in the salification process; "phosgene ratio" represents the molar amount of phosgene based on 1 mol of 1,3 - H6XDA hydrochloride in the phosgenation process; "recombinant recovery ratio" represents the mass percentage of the recombinant (recovery material) in the mixture in the recombinant recovery process.

[0192] Table 2

[0193]

[0194]

[0195] Examples 11 - 15, Comparative Examples 5 - 6

[0196] An NBDI composition and its preparation method. The effective factor E of the NBDI composition is shown in Table 3 respectively. The process flow of its preparation method is the same as that of Example 1, except that 1,3 - XDA in the salification process is replaced by NBDA, and the feed rate remains the same, both being 1000 parts by mass / h of an amine solution of 1,3 - NBDA (norbornanedimethylamine) (mass concentration is 8.0 wt.%, and the solvent is chlorobenzene). There are some process parameters different, which are specifically shown in Table 3 (the processes / parameters not shown in Table 3 are exactly the same as those in Example 1). In Table 3, "HCl ratio" represents the molar amount of HCl based on 1 mol of NBDA in the salification process; "phosgene ratio" represents the molar amount of phosgene based on 1 mol of NBDA hydrochloride in the phosgenation process; "recombinant recovery ratio" represents the mass percentage of the recombinant (recovery material) in the mixture in the recombinant recovery process.

[0197] Table 3

[0198]

[0199]

[0200] Examples 16 - 18 and Comparative Examples 7 - 9

[0201] The method in Example 1 of the prior art US005196572A was used to prepare XDI as Comparative Example 7. This comparative example was to prepare XDI by pyrolysis method, and the product contained no chlorine and thus no effective factor. The recycled heavy fraction in Example 1 was added to this product at a ratio of 4% (i.e., the mass percentage of the heavy fraction in the obtained mixture was 4%) to obtain Example 16.

[0202] Similarly, the method in Example 1 of US005196572A was used to prepare H6XDI. The raw material was replaced with dimethyl 1,3 - cyclohexanedimethyl dicarbamate, and other reaction conditions remained unchanged, as Comparative Example 8. The recycled heavy fraction in Example 6 was added to this product at a ratio of 4% (i.e., the mass percentage of the heavy fraction in the obtained mixture was 4%) to obtain Example 17.

[0203] Similarly, the method in Example 1 of US005196572A was used to prepare NBDI. The raw material was replaced with dimethyl norbornane - 1,3 - dimethylene dicarbamate as Comparative Example 9. The recycled heavy fraction in Example 11 was added to this product at a ratio of 4% (i.e., the mass percentage of the heavy fraction in the obtained mixture was 4%) to obtain Example 18.

[0204] Application Example

[0205] An optical material, specifically a plastic lens material, is a polythiourethane resin formed by polymerization of isocyanate substances and polythiol compounds. The isocyanate substances are respectively the isocyanate compositions provided in Examples 1 - 18 and Comparative Examples 1 - 9, and the polythiol compound is 1,2 - bis((2 - mercaptoethyl)thio)-3 - mercaptopropane.

[0206] The specific preparation method of the optical material is as follows:

[0207] Charge 0.001 part by mass of dibutyltin dichloride, 0.07 part by mass of an internal mold release agent (ZELEC UN, an acidic phosphate ester manufactured by Stepan), 0.05 part by mass of an ultraviolet absorber (Biosorb 583 manufactured by Sakai Chemical Industry Co., Ltd.), and 36.4 parts by mass of an XDI composition (Examples 1-5, 16, Comparative Examples 1-2, 7) into a flask; for the H6XDI composition, the mass is 37.7 parts by mass (Examples 6-10, 17, Comparative Examples 3-4, 8), and for the NBDI composition, the mass is 39.9 parts by mass (Examples 11-15, 18, Comparative Examples 5-6, 9). Then, stir at 25°C for 1 h to dissolve them sufficiently to obtain a polyisocyanate component;

[0208] Charge 33.6 parts by mass of 1,2-bis((2-mercaptoethyl)thio)-3-mercaptopropane into the polyisocyanate component and mix to prepare a polymerizable composition;

[0209] Perform a defoaming treatment on the polymerizable composition at a pressure of 600 Pa for 1 h, then filter it through a 3-μm PTFE filter and inject it into a mold formed by a glass mold and tape. Place the mold in an oven, slowly heat it from 10°C to 120°C, and perform polymerization for 18 h. After the polymerization is completed, take out the mold from the oven, demold it, and obtain the optical material.

[0210] Perform performance tests on the aforementioned optical material as follows:

[0211] (1) Test of yellowness index (YI value)

[0212] Measure the yellowness index of the lens according to the method in GB / T 2409-1980 of the national standard;

[0213] Make the optical material to be tested into a circular flat plastic lens with a thickness of 9 mm and a diameter of 75 mm, use a spectrophotometer to measure the tristimulus values x, y, z; calculate the YI value through the following formula:

[0214]

[0215] The smaller the YI value, the better the hue of the plastic lens; the larger the YI value, the worse the hue.

[0216] (2) Test of optical deformation incidence

[0217] Optical deformation refers to the phenomenon that the local refractive index is different from that of the surrounding normal due to reasons such as different compositions of the material. In the present invention, 100 lenses (with the same specifications as those in the YI value test) were visually observed under a high-pressure mercury lamp, and the lenses with stripes were determined as lenses with optical deformation. The incidence rate of optical deformation was calculated, that is, the incidence rate of optical deformation = 100% × the number of lenses with optical deformation / 100.

[0218] (3) Transmittance test

[0219] The transmittance of the lens was tested according to GB / T 10810.3-2006 "Optical elements and related products for ophthalmic optics - Part 3: Transmittance specifications and measurement methods".

[0220] (4) Glass transition temperature (Tg) test

[0221] The glass transition temperature Tg was tested by differential scanning calorimetry (DSC method). Each sample was tested in parallel 3 times, and the average value was taken;

[0222] Glass transition temperature (Tg) test: A high-pressure differential scanning calorimeter (METTLER HPDSC 1) from Mettler Toledo was used. DSC test method: 30°C - 300°C, heating scan, heating rate of 10°C / min, nitrogen atmosphere, nitrogen flow rate of 50 mL / min.

[0223] The specific test results are shown in Tables 4, 5 and 6:

[0224] Table 4

[0225]

[0226] Table 5

[0227]

[0228]

[0229] Table 6

[0230]

[0231] Combined with the above performance test data, it can be seen that by controlling the effective factor of the isocyanate composition within the range of 3.90 - 5.70, the prepared polythiourethane optical material has a lower yellowness index and an optical deformation incidence rate, and the optical deformation incidence rate is 0 - 1%. Among them, for the optical material prepared from the XDI composition, the yellowness index YI ≤ 1.60, YI is 1.41 - 1.60, the transmittance is 83.95 - 84.10%, and the Tg is 84.56 - 85.67 °C; for the optical material prepared from the H6XDI composition, YI ≤ 1.50, YI is 1.31 - 1.50, the transmittance is 86.03 - 86.72%, and the Tg is 89.08 - 89.67 °C; for the optical material prepared from the NBDI composition, YI ≤ 1.50, YI is 1.32 - 1.50, the transmittance is 85.89 - 86.85%, and the Tg is 108.08 - 108.65 °C, which has both excellent optical properties and heat resistance.

[0232] The applicant declares that the present invention uses the above embodiments to illustrate the isocyanate composition, modified isocyanate, polyurethane resin and optical material of the present invention, but the present invention is not limited to the above process steps, that is, it does not mean that the present invention must rely on the above process steps to be implemented. Those skilled in the art should understand that any improvement to the present invention, the equivalent substitution of the raw materials selected for 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. An isocyanate composition, characterized in that, the effective factor of the isocyanate composition is 3.90 - 5.70; the calculation formula of the effective factor is shown in Formula I: wherein, E is the effective factor; A is the mass content of chlorine in the isocyanate composition; B is the mass content of chloro isocyanate in the isocyanate composition; M Cl is the relative atomic mass of chlorine; M B is the relative molecular mass of the chloro isocyanate.

2. The isocyanate composition according to claim 1, characterized in that, A is obtained by X-ray fluorescence spectrometry; preferably, B is obtained by chromatography-mass spectrometry, and more preferably by gas chromatography-mass spectrometry.

3. The isocyanate composition according to claim 1 or 2, characterized in that, the isocyanate is a diisocyanate, preferably including any one or a combination of at least two of xylylene diisocyanate, bis(isocyanate methyl)cyclohexane, and bis(isocyanate methyl)norbornane; preferably, the mass percentage content of isocyanate in the isocyanate composition is ≥97%.

4. The isocyanate composition according to any one of claims 1-3, characterized in that, the substances corresponding to the effective factor include any one or a combination of at least two of the following compounds: wherein, R is a divalent group obtained by removing the NCO group in the isocyanate; Preferably, the R is selected from any one or a combination of at least two thereof; wherein, the wavy line represents the connection site of the group.

5. The isocyanate composition according to any one of claims 1-4, characterized in that, the chloro isocyanate is a compound obtained by substituting one NCO group in the isocyanate with chlorine; Preferably, the chloro isocyanate includes any one or a combination of at least two thereof.

6. A preparation method of the isocyanate composition according to any one of claims 1-5, characterized in that, the preparation method includes: reacting an amine compound with phosgene to obtain the isocyanate composition.

7. The preparation method according to claim 6, characterized in that, the preparation method includes the following steps: (1) Reacting an amine compound with phosgene to obtain a reaction product; (2) Performing a removal treatment on the reaction product obtained in step (1) to obtain a crude product; the removal treatment includes phosgene removal treatment and / or solvent removal treatment; (3) Separating and refining the crude product obtained in step (2) in sequence to obtain the isocyanate composition; preferably, in step (3), a first-stage heavy component and an intermediate product are separated; the first-stage heavy component is separated again to obtain a heavy component recovery material and a residual heavy component, and the mixture of the intermediate product and the heavy component recovery material is refined to obtain the isocyanate composition; the mass percentage content of the heavy component recovery material in the mixture is 1-10%; preferably, the refining method is distillation.

8. A modified isocyanate, characterized in that, the modified isocyanate is modified by the isocyanate composition according to any one of claims 1-5; the modified isocyanate contains any one or a combination of at least two of the groups (a)-(i): (a) isocyanurate group, (b) uretdione group, (c) biuret group, (d) carbamate group, (e) urea group, (f) iminooxadiazinedione group, (g) urethane group, (h) uretonimine group, (i) carbodiimide group.

9. A polyurethane resin, It is characterized in that the polyurethane resin is formed by the reaction of an isocyanate substance with a substance containing an active hydrogen group; the isocyanate substance includes at least one of the isocyanate compositions described in any one of claims 1-5 and the modified isocyanate described in claim 8.

10. An optical material It is characterized in that the optical material is formed by the polymerization of an isocyanate substance with a polythiol compound; the isocyanate substance includes at least one of the isocyanate compositions described in any one of claims 1-5 and the modified isocyanate described in claim 8; Preferably, the polythiol compound includes at least one of 1,2-bis((2-mercaptoethyl)thio)-3-mercaptopropane, bis(mercaptomethyl)-3,6,9-trithia-1,11-undecanedithiol, pentaerythritol tetra(3-mercaptopropionate), 1,1,3,3-tetra(mercaptomethylthio)propane, or 2-mercaptoethanol; Preferably, the optical material is applied to lenses, prisms, lamp cover materials, transparent packaging materials, transparent building materials, or electronic products.

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