Xylylene diisocyanate composition and preparation method thereof

Abstract

The invention provides a technology. The technology relates to a xylylene diisocyanate composition for controlling the content of low-boiling-point compounds and a preparation method of the xylylene diisocyanate composition. The invention provides a technology. The present technology relates to a xylylene diisocyanate composition capable of preparing a high-purity xylylene diisocyanate compound in high yield by controlling the purity of an amine compound and controlling the content range of a low-boiling-point compound in a reactant when preparing xylylene diisocyanate using phosgene, and a method for preparing the same .

Description

Technical Field

[0001] Cross-reference to related applications

[0002] This application is based on and claims priority to Korean Patent Application Nos. 10-2022-0153715 and 10-2023-0159228, filed on November 16, 2022 and November 16, 2023, respectively, the entire disclosures of which are incorporated herein by reference.

[0003] The present invention relates to a xylylene diisocyanate composition for controlling the content of low-boiling compounds and a method for preparing the same. Background Art

[0004] Xylylene diisocyanate (hereinafter referred to as XDI) is classified as an aliphatic isocyanate although it contains an aromatic ring, and is a very useful compound as a raw material for materials such as polyurethane-based materials, polyurea-based materials, or polyisocyanurate-based materials in the fields of the chemical industry, resin industry, and coating industry.

[0005] Generally, aliphatic isocyanates are prepared by a phosgenation method in which a raw material amine is reacted with phosgene. For example, XDI is prepared by reacting xylylenediamine (hereinafter referred to as XDA) with phosgene. However, since XDI has a high amino reactivity similar to the characteristics of aliphatic isocyanates, many side reactions occur in the phosgenation reaction, and impurities generated by the side reactions affect the production process of polyurethane resins, resulting in a problem of deterioration in resin quality.

[0006] Therefore, many methods for preparing high-purity XDI by reducing the content of generated impurities have been studied and proposed.

[0007] Specifically, Korean Patent Publication No. 1994-0001948 discloses a method for preparing high-purity XDI by using an ester-based compound such as amyl acetate or hexyl acetate as a reaction solvent in the process of preparing xylylene diisocyanate by reacting xylylenediamine or its hydrochloride with phosgene. However, this method has problems such as expensive solvents, and still low purity and yield.

[0008] In addition, Korean Patent No. 0953019 discloses a method for preparing an isocyanate by a phosgenation reaction of an amine hydrochloride, which is prepared by a salting process in which a linear or cyclic aliphatic amine is reacted with hydrogen chloride, and pressure is applied during the salting process to solve the problem of transfer of the amine hydrochloride.

[0009] As a phosgene-free method, Korean Patent No. 1318828 discloses a method for preparing xylylene diisocyanate by a phosgene-free method, in which a diamine compound is reacted with an alkyl chloroformate or a dialkyl carbonate to prepare a bisurethane, and then it is thermally decomposed to degrade and remove an alcohol having a relatively low boiling point. However, compared with the phosgenation method, this method has disadvantages in terms of cost and is difficult to apply to industrial mass production. Summary of the Invention

[0010] Technical Problem

[0011] The present invention provides a technology related to an xylylene diisocyanate composition for controlling the content of low-boiling compounds and a method for preparing the same.

[0012] The present invention provides a method for preparing xylylene diisocyanate, which can prepare a high-purity xylylene diisocyanate compound in a high yield by controlling the purity of an amine compound and the content range of specific low-boiling compounds in a reactant when preparing xylylene diisocyanate using phosgene.

[0013] The present invention also provides a method for economically preparing a high-purity xylylene diisocyanate compound, in which a salt-forming reaction is carried out under specific conditions to utilize the reaction heat generated by the corresponding reaction, thereby improving the process efficiency of the phosgene reaction.

[0014] Technical Solution

[0015] According to an embodiment of the present invention, there is provided an xylylene diisocyanate composition, which comprises:

[0016] an xylylene diisocyanate compound; and

[0017] low-boiling compounds containing isocyanomethylbenzaldehyde and isocyanomethylbenzonitrile,

[0018] wherein, relative to the total amount of the composition, the content of the low-boiling compounds is 1% or less.

[0019] According to an embodiment of the present invention, there is provided a method for preparing an xylylene diisocyanate composition, the method comprising:

[0020] In the first step, an amine compound is reacted with hydrogen chloride in a solvent at 20°C to 90°C under normal pressure to obtain an amine salt compound;

[0021] In the second step, the amine salt compound is reacted with phosgene to obtain a reaction mixture containing an xylylene diisocyanate compound; and

[0022] In the third step, the solvent and unreacted phosgene are removed from the reaction mixture to prepare a benzodimethylenediisocyanate composition,

[0023] wherein the solvent is one or more selected from chlorobenzene, 1,2-dichlorobenzene, 1,4-dichlorobenzene, 1,2,3-trichlorobenzene, and 1,2,4-trichlorobenzene,

[0024] the purity of the amine compound is 99.0% or more, and

[0025] relative to the total amount of the composition, the benzodimethylenediisocyanate composition contains 1% or less of low-boiling compounds, and the low-boiling compounds include isocyanomethylbenzaldehyde and isocyanomethylbenzonitrile.

[0026] According to another embodiment of the present invention, a method for preparing a polyisocyanate composition is provided, the method comprising:

[0027] In the first step, an amine compound is reacted with hydrogen chloride in a solvent at 20°C to 90°C under normal pressure to obtain an amine salt compound;

[0028] In the second step, the amine salt compound is reacted with phosgene to obtain a reaction mixture containing a benzodimethylenediisocyanate compound;

[0029] In the third step, the solvent and unreacted phosgene are removed from the reaction mixture to prepare a benzodimethylenediisocyanate composition; and

[0030] In the fourth step, the benzodimethylenediisocyanate composition is polymerized with a polyol to synthesize a polyisocyanate compound,

[0031] wherein the solvent is one or more selected from chlorobenzene, 1,2-dichlorobenzene, 1,4-dichlorobenzene, 1,2,3-trichlorobenzene, and 1,2,4-trichlorobenzene,

[0032] the purity of the amine compound is 99.0% or more, and

[0033] relative to the total amount of the composition, the benzodimethylenediisocyanate composition contains 1% or less of low-boiling compounds, and the low-boiling compounds include isocyanomethylbenzaldehyde and isocyanomethylbenzonitrile.

[0034] According to still another embodiment of the present invention, a polymerizable composition is provided, which comprises:

[0035] the above-mentioned benzodimethylenediisocyanate composition; and

[0036] one or more of i) a compound based on a polyfunctional thiol and ii) a polyfunctional episulfide compound.

[0037] According to another embodiment of the present invention, there is provided an optical article comprising a polythiourethane polymer prepared from the polymerizable composition.

[0038] Beneficial effects

[0039] The benzylidene diisocyanate composition according to the present invention can prepare a high-purity polyisocyanate compound in high yield by controlling the content range of specific low-boiling compounds during the synthesis of polyisocyanate, and no additional impurities are generated.

[0040] In addition, the method for preparing a benzylidene diisocyanate composition according to the present invention can prepare a high-purity benzylidene diisocyanate compound in high yield through a simple preparation process of controlling the purity of the reaction composition and simultaneously controlling the content range of specific low-boiling compounds in the by-products. In addition, the method for preparing a benzylidene diisocyanate composition according to the present invention can economically prepare a high-purity benzylidene diisocyanate compound by controlling the salt-forming reaction conditions of the amine compound within an appropriate range, thereby improving the process efficiency of the subsequent phosgenation reaction.

[0041] In addition, the method for preparing a polyisocyanate composition according to the present invention can prepare a high-purity polyisocyanate compound in high yield by controlling the purity of the reaction composition and simultaneously controlling the content range of specific low-boiling compounds in the by-products. Detailed embodiments

[0042] The terms used in this specification are only for explaining the exemplary embodiments and are not intended to limit the present invention. Unless otherwise specified in the context, singular expressions also include plural expressions. It must be understood that terms such as "comprising", "equipped with" or "having" in this specification are only used to indicate the presence of the implemented features, quantities, steps, components or combinations thereof, and do not exclude the possibility of adding one or more different features, quantities, steps, components or combinations thereof in advance.

[0043] Although the present invention can be modified and in alternative forms, specific embodiments will be described in detail below. However, it should be understood that this specification is not intended to limit the present invention to the specific forms disclosed, but on the contrary, it is intended to cover all modifications, equivalents and alternatives falling within the spirit and scope of the present invention.

[0044] Generally, the preparation of isocyanate compounds by phosgenation reaction is carried out through the reaction of amine compounds with phosgene, and various impurities are produced as by-products at this time. The inventors of the present invention studied the influence of the application of polyisocyanates polymerized from isocyanates containing these impurities on actual products, and confirmed that by controlling the purity of the solvent and the amine compound as a reactant, and at the same time controlling the content of low-boiling compounds in the reaction mixture within a specific range (about 1% or less), high-purity isocyanates can be prepared in high yield, thus completing the present invention.

[0045] Specifically, low-boiling compounds in the reaction by-products generate additional impurities during the synthesis of polyisocyanates, interfere with the activity of the catalyst, affect the reaction rate, and thus affect the product quality. However, by controlling the content within an appropriate range as described above, high-quality products without such problems can be prepared, and when such high-purity polyisocyanate compounds are applied to optical products, the defect rate can be significantly reduced and the reproducibility can be improved.

[0046] In addition, the amine compound used in the phosgenation reaction is prepared in the form of a chloride through a salt-forming reaction. In the present invention, the salt-forming reaction is carried out under relatively mild conditions in the presence of a specific solvent, so the phosgenation reaction can be easily carried out, and no additional cooling or heating process is required in the phosgenation reaction, thus having excellent economic benefits.

[0047] <Benzene diisocyanate composition>

[0048] According to an embodiment of the present invention, a benzene diisocyanate composition is provided, which comprises a benzene diisocyanate compound; and low-boiling compounds comprising isocyanomethylbenzaldehyde and isocyanomethylbenzonitrile, wherein the content of the low-boiling compounds is 1% or less relative to the total amount of the composition. Here, the content range of the low-boiling compounds is determined by the GC area (%) analyzed by gas chromatography (GC), and the specific measurement method will be described in more detail in the following experimental examples.

[0049] Meanwhile, when the content of the low-boiling compounds in the composition exceeds 1%, they may generate additional impurities during the synthesis of polyisocyanates, interfere with the activity of the catalyst, affect the reaction rate, and thus affect the product quality. However, by using the benzene diisocyanate composition with the content of the low-boiling compounds controlled within an appropriate range as described above, high-purity polyisocyanates can be prepared without such problems, and when such polyisocyanate compounds are applied to optical products, the defect rate can be significantly reduced and the reproducibility can be improved.

[0050] Relative to the total amount of the xylylene diisocyanate composition, the content of the above-mentioned low-boiling compounds can preferably be 0.7% or less, 0.5% or less, or 0.3% or less. The lower limit of the low-boiling compounds is 0% or more. Preferably, the content of the low-boiling compounds can be 0.0001% or more, 0.0001% to 0.7%, or 0.001% to 0.5%, and the above content ranges are suitable for achieving the above effects.

[0051] Relative to the total amount of the composition, the content of isocyanatomethylbenzaldehyde (IMBAI) can be 0.0001% to 0.15%. Preferably, the content can be 0.001% to 0.15%, or 0.0003% to 0.11%.

[0052] In addition, relative to the total amount of the composition, the content of isocyanatomethylbenzonitrile (IMBN) can be 0.0001% to 0.1%. Preferably, the content can be 0.0003% to 0.1%, or 0.0008% to 0.06%.

[0053] According to one embodiment of the present invention, the low-boiling compounds may further include chloromethylbenzyl isocyanate (CMBI). In this case, relative to the total amount of the composition, the content of chloromethylbenzyl isocyanate can be 0.01% to 0.2%. Preferably, the content can be 0.05% to 0.15%.

[0054] In addition to the above components, the xylylene diisocyanate composition may further include additional additives to maintain storage stability.

[0055] The types of the additional additives are not particularly limited and may further include antioxidants, heat stabilizers, polymerization inhibitors, etc. commonly used in the art. The content of the additives is not particularly limited and can be used within an appropriate range that does not hinder the purpose of the present invention.

[0056] Due to its excellent physical properties, the xylylene diisocyanate composition can be widely used in many fields such as optical products.

[0057] The xylylene diisocyanate composition can be prepared according to the following preparation method.

[0058] <Preparation Method of Xylylene Diisocyanate Composition>

[0059] Specifically, according to one embodiment of the present invention, the method for preparing a xylylene diisocyanate composition includes: reacting an amine compound with hydrogen chloride at normal pressure at 20°C to 90°C in a solvent to obtain an amine salt compound; reacting the amine salt compound with phosgene to obtain a reaction mixture containing a xylylene diisocyanate compound; and a third step of removing the solvent and unreacted phosgene from the reaction mixture to prepare the xylylene diisocyanate composition.

[0060] (Salt formation reaction)

[0061] First, perform the first step (salt formation reaction) by reacting an amine compound with hydrogen chloride in a solvent at normal pressure and a temperature of 20°C to 90°C to obtain an amine salt compound.

[0062] The salt formation reaction to obtain the amine salt compound is carried out at normal pressure in a specific solvent at a temperature of 20°C to 90°C. Therefore, the phosgenation reaction can be easily carried out without additional cooling or heating in the subsequent phosgenation reaction, thus having excellent economic benefits.

[0063] Here, normal pressure refers to the pressure when no decompression equipment (such as a separate vacuum pump, etc.) is used. For example, it can correspond to about 760 mmHg, that is, the general atmospheric condition. When carried out within the above range, it is preferred to maintain the homogeneous state of the amine salt compound. When the salt formation reaction is carried out by applying a pressure other than normal pressure conditions, the particle size of the amine salt compound may become uneven.

[0064] On the other hand, when the salt formation reaction is carried out at a temperature below 20°C, the particle size of the amine salt compound may become uneven, thereby inhibiting the subsequent phosgenation reaction. In addition, when the salt formation reaction is carried out at a temperature above 90°C, there is a problem that the salt formation reaction itself is difficult to control. The salt formation reaction is preferably carried out at a temperature of 30°C to 80°C. At the same time, the temperature of the salt formation reaction can be controlled by the heat of reaction generated by introducing hydrogen chloride without special temperature control.

[0065] The solvent is one or more selected from chlorobenzene, 1,2-dichlorobenzene, 1,4-dichlorobenzene, 1,2,3-trichlorobenzene, and 1,2,4-trichlorobenzene. These solvents are all inert organic solvents, which help to reduce the content of by-products. In addition, these solvents help to dissolve the amine salt compound due to their relatively high polarity, thereby promoting the reaction. Most preferably, 1,2-dichlorobenzene can be used. At the same time, when a solvent such as n-amyl acetate is used, the particle size of the amine salt compound may become uneven, thereby inhibiting the phosgenation reaction.

[0066] Preferably, the purity of the solvent can meet more than 99.0%, thereby minimizing side reactions in the phosgenation reaction. In particular, the content of low-boiling compounds in the by-products can be controlled within the above range, thereby preparing high-purity xylylene diisocyanate. More preferably, the purity of the solvent is 99.0% to 99.99%. In terms of achieving the above effects, the above content range is preferred.

[0067] When the purity of the amine compound meets or exceeds 99.0%, side reactions in the phosgenation reaction can be minimized, especially by controlling the content of low-boiling compounds in the by-products within the above range, thereby preparing a high-purity benzylidene diisocyanate compound. More preferably, the purity of the amine compound is from 99.0% to 99.99%. For achieving the above effects, the above content range is preferred.

[0068] The amine compound can be one or more selected from m-xylylenediamine, p-xylylenediamine, o-xylylenediamine, and their chlorides (e.g., hydrochloride or carbonate, etc.). Preferably, the chloride of the amine compound can be used, which is beneficial to reducing the impurity content by increasing the product conversion rate during the preparation process of the xylene diisocyanate compound described below.

[0069] More specifically, the amine compound can be obtained through the following reactions, and its purity can be within the above range:

[0070] 1) m-Xylene ammoxidation reaction

[0071]

[0072] 2) IPN hydrogenation reaction

[0073]

[0074] The synthesis steps of XDA are as follows: In the first step, m-xylene is subjected to ammoxidation reaction to prepare isophthalonitrile (IPN); then the second step of hydrogenation reaction is carried out. The impurity numbers that may be generated during the second-step synthesis are #1 to #3 respectively. In addition, various other impurities may also be generated, but the content of these impurities is very low (about 1% or less).

[0075] Meanwhile, these impurities may affect the content of low-boiling compounds in the process of obtaining the reaction mixture containing benzylidene diisocyanate compound described below. In other words, the higher the purity of the amine compound, the lower the content of low-boiling compounds.

[0076] Relative to the total amount of the solvent, the content of the amine compound can be 1 wt% to 20 wt%. When the content of the amine compound exceeds 20 wt%, it is difficult to stir during the reaction process, a large amount of amine compound may precipitate, and the uneven reaction will affect the increase in the content of low-boiling compounds. The content of the amine compound is preferably 1 wt% to 15 wt%, or 5 wt% to 15 wt%.

[0077] (Phosgenation reaction)

[0078] Next, including the second step, reacting the amine salt compound with phosgene to obtain a reaction mixture containing a benzylidene diisocyanate compound.

[0079] By carrying out the salt-forming reaction under the above conditions, a homogeneous chloride is obtained, and thus the phosgenation reaction can be carried out more easily.

[0080] The reaction temperature is not particularly limited, but the reaction can be carried out at 110 °C to 160 °C, more preferably at 120 °C to 140 °C. When the reaction temperature is higher than 160 °C, the concentration of by-products increases, and problems such as thermal decomposition of reactants and products may occur.

[0081] Preferably, the reaction can be carried out by gradually raising the temperature in the reactor to the above range and then injecting phosgene; more preferably, the reaction can be carried out by controlling the temperature in the reactor at 110 °C to 140 °C after injecting phosgene. The reactor temperature can preferably be controlled at 120 °C to 135 °C.

[0082] In addition, according to an embodiment of the present invention, in the reaction of the amine salt compound with phosgene, the method of injecting phosgene is not particularly limited. For example, after introducing the amine salt compound and phosgene into a single reactor, they can be simply stirred, or the reaction can be carried out by injecting phosgene into the reactor containing the amine salt compound through a mixing injector (i.e., a mixing nozzle). Preferably, the reaction can be carried out by injecting phosgene through a mixing injector, which is beneficial to the uniform mixing of reactants and improves the reaction efficiency, thereby shortening the reaction time and reducing the impurity content, which is preferred.

[0083] The reaction time is not particularly limited, but after the injection of phosgene is completed, the reaction can be carried out for about 1 hour to about 4 hours. Preferably, the reaction can be carried out for 1 hour to 3 hours.

[0084] In addition, it is preferred that after the reaction is completed, a process of further reducing the internal temperature of the reactor to 70 °C to 80 °C is carried out.

[0085] (Purification process)

[0086] Next, it includes the third step of removing the solvent and unreacted phosgene from the reaction mixture to prepare a benzodimethyl diisocyanate composition.

[0087] After the phosgene reaction is completed, the solvent, unreacted phosgene, etc. still remain in the reaction mixture, which can be removed to prepare a benzodimethyl diisocyanate composition containing a benzodimethyl diisocyanate compound.

[0088] At the same time, according to an embodiment of the present invention, after removing the solvent and unreacted phosgene from the reaction mixture, the third step can further include a purification process.

[0089] The method for removing the solvent, phosgene and the purification process is not particularly limited, and the methods commonly used in the art can be adopted. For example, the unreacted phosgene and hydrogen chloride gas remaining in the reaction mixture can be removed by nitrogen bubbling method, and the solvent can be removed by distillation method.

[0090] The purification process can be carried out by purification via vacuum fractionation and thin-film distillation. In the factory process, the fractionation can be carried out using a tray distillation column or a packed distillation column. The number of theoretical plates of the distillation column is 2 or more, preferably 5 or more. Preferably, the number is 50 or less, 40 or less.

[0091] Relative to the total amount of the composition, the benzylidene diisocyanate composition prepared according to the above salt formation reaction, phosgenation reaction and purification process contains 1% or less of low-boiling compounds. Here, the low-boiling compounds include isocyanomethylbenzaldehyde and isocyanomethylbenzonitrile. The content range of the low-boiling compounds is determined by gas chromatography (GC) analysis of the GC area (%), and the specific measurement method will be described in more detail in the experimental examples below.

[0092] When the content of the low-boiling compounds exceeds 1%, additional impurities may be generated during the subsequent polyisocyanate synthesis process, and the activity of the catalyst may be inhibited, affecting the reaction rate. Therefore, the product quality may be affected. However, when using the benzylidene diisocyanate composition with the content controlled within an appropriate range as described above, high-purity polyisocyanate can be prepared without these problems, and such polyisocyanate compounds can significantly reduce the defect rate and improve the reproducibility when applied to optical articles.

[0093] Relative to the total amount of the benzylidene diisocyanate composition, the content of the low-boiling compounds can preferably be 0.7% or less, 0.5% or less, or 0.3% or less. The lower limit of the low-boiling compounds is 0% or more. Preferably, their content can be 0.0001% or more, 0.0001% to 0.7%, or 0.001% to 0.5%. The above content ranges are conducive to achieving the above effects.

[0094] Relative to the total amount of the composition, the content of isocyanomethylbenzaldehyde (IMBAI) can be 0.0001% to 0.15%, preferably 0.001% to 0.15%, or 0.0003% to 0.11%.

[0095] In addition, relative to the total amount of the composition, the content of isocyanomethylbenzonitrile (IMBN) can be 0.0001% to 0.1%, preferably 0.0003% to 0.1%, or 0.0008% to 0.06%.

[0096] According to one embodiment of the present invention, the low-boiling compound may further contain chloromethylbenzyl isocyanate (CMBI). In this case, the content of chloromethylbenzyl isocyanate may be 0.01% to 0.2%, preferably 0.05% to 0.15% based on the total amount of the composition.

[0097] <Polymerizable composition>

[0098] According to one embodiment of the present invention, there is provided a polymerizable composition comprising:

[0099] The above-mentioned xylylene diisocyanate composition; and

[0100] One or more of i) a compound based on a polyfunctional thiol and ii) a polyfunctional episulfide compound.

[0101] The polymerizable composition may contain an isocyanate composition, a compound based on a polyfunctional thiol, and a compound based on a polyfunctional episulfide, and the isocyanate composition, the compound based on a polyfunctional thiol, and the compound based on a polyfunctional episulfide may be in a mixed state or in a separated state from each other. In other words, in the polymerizable composition, the isocyanate composition and the compound based on a polyfunctional thiol or the compound based on a polyfunctional episulfide may be in a mixed state in contact with each other or in a separated state not in contact with each other.

[0102] The compound based on a polyfunctional thiol may be a compound containing two or more thiol (-SH) groups in the molecule and may have an aliphatic, alicyclic or aromatic skeleton.

[0103] The compound based on a polyfunctional episulfide is a compound containing two or more episulfide groups (i.e., thioepoxy groups) in the molecule and may have an aliphatic, alicyclic or aromatic skeleton.

[0104] According to one embodiment, the polyfunctional alcohol-based compound may include one or more selected from the following: 4,8-bis(mercaptomethyl)-3,6,9-trithiaundecane-1,11-dithiol, 4,7-bis(mercaptomethyl)-3,6,9-trithiaundecane-1,11-dithiol, 5,7-bis(mercaptomethyl)-3,6,9-trithiaundecane-1,11-dithiol, bis(2-mercaptoethyl)sulfide, 4-mercaptomethyl-3,6-dithiaoctane-1,8-dithiol, 2,3-bis(2-mercaptoethylthio)propane-1-thiol, 2,2-bis(mercaptomethyl)propane-1,3-dithiol, 2-(2-mercaptoethylthio)propane-1,3-dithiol, 2-(2,3-bis(2-mercaptoethylthio)propylthio)ethanethiol, bis(2,3-dimercaptopropyl)sulfide, bis(2,3-dimercaptopropyl)disulfide, 1,2-bis(2-(2-mercaptoethylthio)-3-mercaptopropylthio)ethane, bis(2-(2-mercaptoethylthio)-3-mercaptopropyl)disulfide, 2-(2-mercaptoethylthio)-2-mercapto-3-[3-mercapto-2-(2-mercaptoethylthio)-propylthio]propylthio-propane-1-thiol, 2-(2-mercaptoethylthio)-3-mercapto-3-[3-mercapto-2-(2-mercaptoethylthio)-propylthio]propylthio-propane-1-thiol, 2-(2-mercaptoethylthio)-3-(2-(2-[3-mercapto-2-(2-mercaptoethylthio)-propylthio]ethylthio)ethylthio)-propane-1-thiol, (4R,11S)-4,11-bis(mercaptomethyl)-3,6,9,12-tetrathiatetradecane-1,14-dithiol, (S)-3-((R-2,3-dimercaptopropyl)thio)propane-1,2-dithiol, 4,14-bis(mercaptomethyl)-3,6,9,12,15-pentathiaheptadecane-1,17-dithiol, (S)-3-((R-3-mercapto-2-((2-mercaptoethyl)thio)propyl)thio)propyl)thio)-2-((2-mercaptoethyl)thio)propane-1-thiol, 3,3'-dithiobis(propane-1,2-dithiol), (7R,11S)-7,11-bis(mercaptomethyl)-3,6,9,12,15-pentathiaheptadecane-1,17-dithiol, (7R,12S)-7,12-bis(mercaptomethyl)-3,6,9,10,13,16-hexathiaoctadecane-1,18-dithiol, 2-(2-mercaptoethylthio)-3-[4-(1-{4-[3-mercapto-2-(2-mercaptoethylthio)-propoxy]-phenyl}-1-methylethyl)-phenoxy]-propane-1-thiol, 2,2-bis-(3-mercaptopropionyloxymethyl)-butylester, pentaerythritol tetra(3-mercaptopropionate), pentaerythritol tetra(2-mercaptoacetate), dipentaerythritol hexa(3-mercaptopropionate), trimethylolpropane tri(2-mercaptopropionate), trimethylolpropane tri(3-mercaptopropionate), glycerol trithioglycolate, 1,1,3,3-tetra(mercaptomethylthio)propane, 1,1,2,2-tetra(mercaptomethylthio)ethane, 4,6-bis(mercaptomethylthio)-1,3-dithiane, 2-(2,2-bis(mercaptomethylthio)ethyl)-1,3-dithiane and 2,5-bis(mercaptomethyl)-1,4-dithiane.,

[0105] According to one embodiment, the compound based on the polyfunctional cyclic sulfide may include one or more selected from the following: bis(β-mercaptopropylthio)methane, 1,2-bis(β-mercaptopropylthio)ethane, 1,3-bis(β-mercaptopropylthio)propane, 1,2-bis(β-mercaptopropylthio)propane, 1-(β-mercaptopropylthio)-2-(β-mercaptopropylthiomethyl)propane, 1,4-bis(β-mercaptopropylthio)butane, 1,3-bis(β-mercaptopropylthio)butane, 1-(β-mercaptopropylthio)-3-(β-mercaptopropylthiomethyl)butane, 1,5-bis(β-mercaptopropylthio)pentane, 1-(β-mercaptopropylthio)-4-(β-mercaptopropylthiomethyl)pentane, 1,6-bis(β-mercaptopropylthio)hexane, 1-(β-mercaptopropylthio)-5-(β-mercaptopropylthiomethyl)hexane, 1-(β-mercaptopropylthio)-2-[(2-β-mercaptopropylthioethyl)thio]ethane, 1-(β-mercaptopropylthio)-2-[[2-(2-β-mercaptopropylthioethyl)thioethyl]thio]ethane, tetra(β-mercaptopropylthiomethyl)methane, 1,1,1-tris(β-mercaptopropylthiomethyl)propane, 1,5-bis(β-mercaptopropylthio)-2-(β-mercaptopropylthiomethyl)-3-thiapentane, 1,5-bis(β-mercaptopropylthio)-2,4-bis(β-mercaptopropylthiomethyl)-3-thiapentane, 1-(β-mercaptopropylthio)-2,2-bis(β-mercaptopropylthiomethyl)-4-thiahexane, 1,5,6-tris(β-mercaptopropylthio)-4-(β-mercaptopropylthiomethyl)-3-thiahexane, 1,8-bis(β-mercaptopropylthio)-4-(β-mercaptopropylthiomethyl)-3,6-dithiaoctane, 1,8-bis(β-mercaptopropylthio)-4,5-bis(β-mercaptopropylthiomethyl)-3,6-dithiaoctane, 1,8-bis(β-mercaptopropylthio)-4,4-bis(β-mercaptopropylthiomethyl)-3,6-dithiaoctane, 1,8-bis(β-mercaptopropylthio)-2,4,5-tris(β-mercaptopropylthiomethyl)-3,6-dithiaoctane, 1,8-bis(β-mercaptopropylthio)-2,5-bis(β-mercaptopropylthiomethyl)-3,6-dithiaoctane, 1,9-bis(β-mercaptopropylthio)-5-(β-mercaptopropylthiomethyl)-5-[(2-β-mercaptopropylthioethyl)thiomethyl]-3,7-dithianonane, 1,10-bis(β-mercaptopropylthio)-5,6-bis[(2-β-mercaptopropylthioethyl)thio]-3,6,9-trithiadecane, 1,11-bis(β-mercaptopropylthio)-4,8-bis(β-mercaptopropylthiomethyl)-3,6,9-trithiaundecane, 1,11-bis(β-mercaptopropylthio)-5,7-bis(β-mercaptopropylthiomethyl)-3,6,9-trithiaundecane, 1,11-bis(β-mercaptopropylthio)-5,7-[(2-β-mercaptopropylthioethyl)thiomethyl]-3,6,9-Trithiaundecane, 1,11-bis(β-mercaptopropylthio)-4,7-bis(β-mercaptopropylthiomethyl)-3,6,9-trithiaundecane, 1,3-bis(β-mercaptopropylthio)cyclohexane, 1,4-bis(β-mercaptopropylthio)cyclohexane, 1,3-bis(β-mercaptopropylthiomethyl)cyclohexane, 1,4-bis(β-mercaptopropylthiomethyl)cyclohexane, bis[4-(β-mercaptopropylthio)cyclohexyl]methane, 2,2-bis[4-(β-mercaptopropylthio)cyclohexyl]propane, bis[4-(β-mercaptopropylthio)cyclohexyl]sulfide, 2,5-bis(β-mercaptopropylthiomethyl)-1,4-dithiane, 2,5-bis(β-mercaptopropylethylthiomethyl)-1,4-dithiane, 1,3-bis(β-mercaptopropylthio)benzene, 1,4-bis(β-mercaptopropylthio)benzene, 1,3-bis(β-mercaptopropylthiomethyl)benzene, 1,4-bis(β-mercaptopropylthiomethyl)benzene, bis[4-(β-mercaptopropylthio)phenyl]methane, 2,2-bis[4-(β-mercaptopropylthio)phenyl]propane, bis[4-(β-mercaptopropylthio)phenyl]sulfide, bis[4-(β-mercaptopropylthio)phenyl]sulfone, and 4,4'-bis(β-mercaptopropylthio)biphenyl.,

[0106] In the polymerizable composition, the molar ratio of (mercapto group + episulfide group) to isocyanate group can be about 0.5 to about 1.5, or about 0.8 to about 1.2, or about 0.9 to about 1.1, but the present invention is not necessarily limited thereto.

[0107] In addition, the polymerizable composition may further contain an appropriate amount of additives, such as mold release agents, heat stabilizers, ultraviolet stabilizers, pigments, urethane reaction catalysts, and the like.

[0108] The mold release agent is a surfactant component and can be, for example, a fluorine-based nonionic surfactant containing a perfluoroalkyl group; a silicone-based nonionic surfactant containing a dimethylpolysiloxane group; quaternary ammonium salts, such as trimethylcetylammonium salt, trimethylstearylammonium salt, dimethylethylcetylammonium salt, triethyldodecylammonium salt, trioctylmethylammonium salt, and diethylcyclohexadecylammonium salt, etc.

[0109] The heat stabilizer can be, for example, a compound based on metal fatty acid salts, a compound based on phosphorus, a compound based on lead, a compound based on organotin, etc. These compounds can be used alone or in combination of two or more.

[0110] The ultraviolet stabilizer can be, for example, a compound based on benzophenone, a compound based on benzotriazole, a compound based on salicylate, a compound based on cyanoacrylate, a compound based on oxanilide, etc.

[0111] The pigment can be, for example, a fluorescent whitening agent, a fluorescent pigment, an inorganic pigment, etc.

[0112] The urethane reaction catalyst can be, for example, a compound based on dialkyltin halide, such as dibutyltin dichloride, dimethyltin dichloride, etc.; a compound based on dialkyltin dicarboxylate, such as dimethyltin diacetate, dibutyltin dioctoate, dibutyltin dilaurate, etc.; a compound based on dialkoxy dialkyltin, such as dibutoxy dibutyltin, dibutoxy dioctyltin, etc.; a compound based on dithioalkoxy dialkyltin, such as bis(thiobutoxy) dibutyltin, etc.; a dialkyltin oxide compound, such as bis(2-ethylhexyl)tin oxide, dioctyltin oxide, bis(butoxydibutyltin) oxide, etc.; or a compound based on dialkyltin sulfide. Any one or a combination of two or more thereof can be used.

[0113] <Optical article>

[0114] Furthermore, according to an embodiment of the present invention, there is provided an optical article comprising a polythiourethane polymer prepared from the polymerizable composition.

[0115] More preferably, the optical article can be an optical lens, such as an eyeglass lens, a camera lens, a plastic lens, a prism, etc.

[0116] <Method for preparing polyisocyanate composition>

[0117] According to another embodiment of the present invention, there is provided a method for preparing a polyisocyanate composition, and the method applies the method for preparing a benzylidene diisocyanate composition.

[0118] Specifically, the method for preparing a polyisocyanate composition according to an embodiment of the present invention includes:

[0119] In the first step, an amine compound is reacted with hydrogen chloride at normal pressure at 20°C to 90°C in a solvent to obtain an amine salt compound;

[0120] In the second step, the amine salt compound is reacted with phosgene to obtain a reaction mixture containing a benzylidene diisocyanate compound;

[0121] In the third step, the solvent and unreacted phosgene are removed from the reaction mixture to prepare the benzylidene diisocyanate composition; and

[0122] In the fourth step, the benzylidene diisocyanate composition is polymerized with a polyol to synthesize a polyisocyanate compound.

[0123] The above method for preparing a benzylidene diisocyanate composition can be equally applicable to all the first, second, and third steps.

[0124] Therefore, the solvent is one or more selected from chlorobenzene, 1,2-dichlorobenzene, 1,4-dichlorobenzene, 1,2,3-trichlorobenzene and 1,2,4-trichlorobenzene, the purity of the amine compound is 99.0% or more, and relative to the total amount of the composition, the benzylidene diisocyanate composition contains 1% or less of low-boiling compounds, and the low-boiling compounds include isocyanomethylbenzaldehyde and isocyanomethylbenzonitrile.

[0125] Next, a fourth step is included of mixing and polymerizing the benzylidene diisocyanate composition with a polyol to synthesize a polyisocyanate compound.

[0126] The isocyanate compound contained in the composition has a high purity, and since the content of the low-boiling compounds in the composition satisfies 1% or less, the generation of by-products in the polymerization step is significantly reduced.

[0127] Preferably, the polyol is a compound containing two or more hydroxyl groups in one molecule, and specifically may be a compound containing two or more, or three or more, and eight or less, or four or less hydroxyl groups.

[0128] Specific examples may include diols such as ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,4-butanediol, 2-methyl-2,3-butanediol, 1,6-hexanediol, 1,2-hexanediol, etc.; triols such as glycerol, trimethylolethane, trimethylolpropane (TMP), etc.; tetrols such as diglycerol, ditrimethylolpropane, pentaerythritol, dipentaerythritol, etc.; pentols such as L-arabitol, ribitol, xylitol, etc.; hexols such as D-glucitol, D-mannitol, galactitol, etc.; heptols such as trehalose, etc.; octols such as sucrose, maltose, etc., or low molecular weight polyols, among which, diethylene glycol, glycerol, trimethylolethane, trimethylolpropane or a mixture thereof can be used. More specifically, a triol such as glycerol, trimethylolpropane or trimethylolethane can be preferably used alone, or a mixture of the triol and other polyols can be used.

[0129] Meanwhile, the polymerization reaction proceeds through a urethane reaction (or addition polymerization reaction) between the isocyanate compound and the hydroxyl groups in the polyol.

[0130] Therefore, it is necessary to appropriately determine the amount of polyol according to the urethane reaction with the isocyanate compound, the physical properties (such as viscosity, etc.) to be achieved by the prepared polyisocyanate, and the use of the polymer. Specifically, the introduced amount of polyol should be such that the molar ratio of the hydroxyl groups in the polyol to the isocyanate groups of 1 mole of the isocyanate compound is 0.05 or more, or 0.15 or more, and 1 or less, or 0.8 or less. When the molar ratio of the hydroxyl group to the isocyanate group is lower than the above molar ratio range and less than 0.05, due to the excess of isocyanate groups, the viscosity of the prepared polymer may decrease, which may reduce the processing performance. In addition, when the molar ratio of the hydroxyl group to the isocyanate group exceeds 1, due to the excess of hydroxyl groups, the effect of preventing discoloration may decrease.

[0131] The polymerization reaction can be carried out under atmospheric pressure and in an inert gas atmosphere such as nitrogen, argon, etc.

[0132] The polymerization reaction is preferably carried out in a temperature range of 40 °C or higher, or 60 °C or higher, and 100 °C or lower, or 80 °C or lower, because in this way, the reaction rate can be easily controlled, there is no need to worry about discoloration, and at the same time, the reaction efficiency can be improved.

[0133] The polymerization reaction can be carried out under non-catalytic conditions or in the presence of a catalyst that usually promotes the urethane reaction (such as a tin-based or amine-based catalyst, etc.). When carried out in the presence of a catalyst, the catalyst can be further introduced when adding the polyol to the monomer composition.

[0134] The progress of the polymerization reaction can be estimated by measuring the concentration of isocyanate groups in the polymerization reaction product by the n-dibutylamine method using a potentiometric titrator or by measuring the refractive index. In the present invention, the polymerization reaction proceeds until the concentration of isocyanate groups in the polymerization reaction product reaches the calculated value of the remaining isocyanate groups after reaction with the polyol.

[0135] Through the above polymerization reaction, polyisocyanate is prepared.

[0136] The polyisocyanate prepared as described above can be used to prepare polyurethane by reacting with polyol, and by using the polyisocyanate of the present invention, the physical properties of the polyurethane product can be precisely controlled.

[0137] Specifically, the polyisocyanate contains urethane bonds formed by the reaction of part or all of the isocyanate groups of the isocyanate compound in the reaction mixture obtained by the above phosgenation reaction with the hydroxyl groups of the polyol.

[0138] In the present invention, the reaction mixture contains a high-purity benzene diisocyanate compound, especially the content of low-boiling compounds is 1% by weight or less. Therefore, high-purity polyisocyanate can be prepared in high yield, and the prepared product will not discolor or become cloudy. More preferably, relative to the total amount of the composition, the content is 0.7% or less, 0.5% or less, or 0.3% or less. The lower limit of the low-boiling compounds is 0% or more, preferably the content is 0.0001% or more, 0.0001% to 0.7%, or 0.001% to 0.5%. The content range of the low-boiling compounds is determined by the GC area (%) analyzed by gas chromatography (GC), and the specific measurement method will be described in more detail in the experiments below.

[0139] In the product obtained from the polymerization reaction, in addition to the polyisocyanate, there may also be a stabilizer and unreacted diisocyanate that did not participate in the polymerization reaction.

[0140] Therefore, the method for preparing a polyisocyanate composition according to an embodiment of the present invention may further optionally include a step of removing unreacted diisocyanate by purifying the product obtained after completion of the polymerization reaction.

[0141] Common purification methods can be used for the purification process, such as distillation or solvent extraction, etc. In the present invention, due to the excellent efficiency of the distillation purification method in removing unreacted polyisocyanate, distillation purification methods such as thin-film distillation can be used for the purification process.

[0142] The pressure and temperature in the distillation purification process can be appropriately controlled according to the composition of the polyisocyanate composition, the distillation device, etc. In the present invention, the distillation purification process can be carried out under a pressure of 0.001 kPa or more, 1 kPa or less, or 0.5 kPa or less.

[0143] In addition, the distillation purification process can be carried out at a temperature of 70 °C or more, or 90 °C or more, and 200 °C or less, or 180 °C or less. When the temperature is lower than 70 °C, the distillation purification efficiency may decrease; when the temperature is higher than 200 °C, the polyisocyanate may deteriorate due to high temperature.

[0144] The above distillation purification process can reduce the content of unreacted diisocyanate in the polyisocyanate composition, and the lower the content, the higher the stability of the composition, so it is preferred.

[0145] <Polyisocyanate composition>

[0146] According to another embodiment of the present invention, there is provided a composition prepared according to the method for preparing a polyisocyanate composition.

[0147] The polyisocyanate composition may further contain a diluting solvent, so it exhibits appropriate coating properties, making it easy to apply to products.

[0148] Preferably, ethyl acetate can be used as a diluting solvent. For example, ethyl acetate can be added to make the solid content of isocyanate groups (NCO%) in the composition reach 75% by weight. When the content of isocyanate groups is within the above range, an appropriate crosslinking density can be exhibited, and excellent film-forming characteristics can be exhibited when applying the polymer composition.

[0149] Meanwhile, in the present invention, NCO% can be obtained by neutralizing isocyanate groups with an excessive amount of 2N amine and then performing back-titration with 1N hydrochloric acid.

[0150] Based on the total weight of solids in the polyisocyanate composition, the content of the remaining unreacted diisocyanate is 1% by weight or less, or 0.5% by weight or less, or 0.3% by weight or less. Therefore, compared with the prior art, the content of unreacted diisocyanate is greatly reduced, thereby exhibiting excellent stability.

[0151] The polyisocyanate composition may also contain additives such as internal mold release agents, ultraviolet absorbers, polymerization initiators, heat stabilizers, color correctors, chain extenders, crosslinking agents, light stabilizers, fillers, etc. as needed, and their contents can be appropriately determined within the range that does not inhibit the coloring and discoloration inhibition performance of the polymer composition.

[0152] The polyisocyanate composition can be widely applied in various fields due to its excellent physical properties. Among them, due to its excellent viscosity / adhesiveness, it can be used as an adhesive or glue.

[0153] Hereinafter, the functions and effects of the present invention will be described in more detail in conjunction with specific exemplary embodiments of the present invention. However, these exemplary embodiments are only for illustrating the present invention and do not limit the scope of the present invention.

[0154] [Preparation Example - Preparation of Benzylidene Diisocyanate Composition]

[0155] Preparation Example 1

[0156] In a reactor, 437 kg of 1,2-dichlorobenzene with a purity of 99.83% and 45.5 kg (10.4% by weight) of m-xylylenediamine (m-XDA) with a purity of 99.5% were stirred at room temperature (about 24°C) and atmospheric pressure (1 atmosphere), and 27 kg of anhydrous hydrochloric acid was injected within 3 hours. While injecting anhydrous hydrochloric acid, as the temperature increased, a salt-forming reaction began. When the reactor was maintained at atmospheric pressure (1 atmosphere) and about 80°C for about 4 hours, the salt-forming reaction proceeded to obtain an amine salt compound.

[0157] Next, 40 kg of phosgene was initially injected into the reactant containing the above-mentioned ammonium salt compound, and the temperature was raised to 120 °C. Further, 300 kg of phosgene was slowly injected into the reactor, and the reactor temperature was maintained at 120 °C to 135 °C. It took 20 hours from the injection of phosgene to the end of the reaction. After the solution became transparent, the inside of the reactor was cooled to 80 °C, and nitrogen was introduced for cooling. A phosgene-removed benzylidene diisocyanate composition was obtained.

[0158] Preparation Example 2

[0159] The amounts used were the same as in Preparation Example 1, but when injecting phosgene, an injection nozzle was installed at the injection end, phosgene was injected at 80 °C, and after the salt formation reaction was completed, the temperature was raised to 120 °C. The temperature inside the reactor was controlled by adjusting the phosgene flow rate. The total reaction time was 15 hours.

[0160] Preparation Example 3

[0161] The amounts used were the same as in Preparation Example 2, but when injecting phosgene, an injection nozzle was installed at the injection end. After the salt formation reaction was completed, the temperature was raised, and phosgene was injected at 120 °C, and the reactor temperature was maintained at 120 °C to 135 °C. The total reaction time was 12 hours.

[0162] [Experimental Example 1: Analysis of Preparation Conditions of Isocyanate Compounds]

[0163] The benzylidene diisocyanate compositions containing various isocyanate compounds prepared in the preparation examples were analyzed by gas chromatography (GC), and the GC area (%) of m-XDI (solvent-free) was shown in Table 1 as the purity of m-XDI.

[0164] <GC Analysis Conditions>

[0165] The phosgenation reaction products were analyzed using GC. The GC used for the analysis was HP-6890, and the detection was carried out using FID. The chromatographic column used was DB-17 (30 m * 0.25 mm * 0.5 μm), the carrier gas was nitrogen (1.0 mL / min), the injection volume was 1 μl, and the column temperature was 80 °C -> 5 °C / min -> 160 °C (8 minutes) -> 20 °C / min -> 280 °C (18 minutes).

[0166] Split ratio: Pulse splitless method

[0167] IMBA1 detection method: SIM (monitoring ions: m / z 161, 132)

[0168] CMBI detection method: SIM (monitoring ions: m / z 181, 146)

[0169] IMBA1 detection method: SIM (monitoring ions: m / z 158, 116)

[0170]

Table 1

[0171] Item Preparation Example 1 Preparation Example 2 Preparation Example 3 Phosgenation reaction time (hours) 20 15 12 m-XDI purity (%) 98.3 98.5 98.9

[0172] As shown in Table 1, it has been confirmed that different phosgene injection methods in the phosgenation reaction result in different reaction uniformities, leading to differences in reaction efficiency. Specifically, it has been confirmed that when using a phosgene mixing injector, as shown in Preparation Examples 2 and 3, phosgene and the amine salt compound can be uniformly mixed, thereby shortening the reaction time and increasing the purity of m-XDI.

[0173] [Examples and Comparative Examples - Preparation of Polyisocyanate Compositions]

[0174] Example 1

[0175] Preparation of isocyanate compounds

[0176] A reaction mixture containing an isocyanate compound (m-XDA: 10.4% by weight) was prepared according to Preparation Example 3, and the solvent was removed from the reaction solution from which phosgene had been removed by vacuum distillation. The product was purified by vacuum fractional distillation and thin-film distillation to obtain a benzodimethylenediisocyanate composition containing an isocyanate compound.

[0177] Preparation of polyisocyanate compositions

[0178] Under a nitrogen atmosphere, 300 g of the prepared benzodimethylenediisocyanate composition containing an isocyanate compound (m-phenylene diisocyanate) was placed in a flask. The temperature of the flask was raised to 70 °C and maintained, and then 26.7 g of trimethylolpropane (TMP) as a polyol was added dropwise. Thereafter, the reaction temperature was maintained at 70 °C until the concentration of isocyanate groups in the flask reached the calculated value of 33%.

[0179] After the reaction was completed, the resulting reaction product was purified using a thin-film evaporator (TFE) to separate unreacted XDI, and diluted with ethyl acetate to a solid content of 75% by weight to obtain a polyisocyanate composition.

[0180] Example 2

[0181] A polyisocyanate composition was obtained in the same manner as in Example 1, except that the content of m-XDA was changed to 8% by weight.

[0182] Example 3

[0183] A polyisocyanate composition was obtained in the same manner as in Example 1, except that the content of m-XDA was changed to 5% by weight.

[0184] Example 4

[0185] An isocyanate compound and a polyisocyanate composition were obtained in the same manner as in Example 1, except that m-XDA with a purity of 99.83% in Example 1 was purified to 99.97% and used.

[0186] Example 5

[0187] A polyisocyanate composition was obtained in the same manner as in Example 4, except that the content of m-XDA was changed to 8% by weight.

[0188] Example 6

[0189] A polyisocyanate composition was obtained in the same manner as in Example 4, except that the content of m-XDA was changed to 5% by weight.

[0190] Comparative Example 1 (direct phosgenation reaction)

[0191] 362 ml of 1,2-dichlorobenzene and 42.7 ml of phosgene were added to a flask, cooled to -10°C to -15°C, and 31.5 ml of m-XDA (8% by volume) was slowly added. After the addition of the amine compound was completed, the reactor temperature was raised to 130°C until the reaction solution became transparent, and the reactor temperature was maintained between 125°C and 135°C to carry out the direct phosgenation reaction. After the reaction solution became transparent, nitrogen was introduced into the reactor, and the temperature was lowered to 80°C. Thereafter, the solvent was removed by vacuum distillation, and the product was purified by vacuum fractional distillation to obtain a composition containing an isocyanate compound and a polyisocyanate composition.

[0192] Comparative Example 2 (control of reactant purity)

[0193] A polyisocyanate composition was obtained in the same manner as in Example 1, except that m-XDA with a purity of 98.0% was used.

[0194] Comparative Example 3 (solvent control)

[0195] A polyisocyanate composition was obtained in the same manner as in Example 1, except that n-amyl acetate was used as the solvent.

[0196] Comparative Example 4 (control of salt-forming reaction process conditions - pressure)

[0197] A polyisocyanate composition was obtained in the same manner as in Example 1, except that during the salt-forming reaction, the pressure was changed to 0.5 kgf / cm2 to 1.02 kgf / cm2 at room temperature.

[0198] Comparative Example 5 (control of salt-forming reaction process conditions - temperature)

[0199] In Example 1, the reactor temperature was heated to about 120 °C during the salt formation reaction to carry out the reaction. As a result, the evaporation amount of XDA·HCl increased, so a large amount of XDA·HCl salt was deposited in the condenser and pipeline of the reactor, and the reaction product could not be obtained. Therefore, the isocyanate composition could not be obtained.

[0200] Comparative Example 6 (Control of Salt Formation Reaction Process Conditions - Temperature)

[0201] A polyisocyanate composition was obtained in the same manner as in Example 1, except that the reactor temperature was cooled to about 15 ± 1 °C during the salt formation reaction.

[0202] [Experimental Example 2: Evaluation of Isocyanate Compounds]

[0203] The reaction mixtures containing various isocyanate compounds prepared in the examples and comparative examples were analyzed by gas chromatography (GC), and the results are shown in Table 2 in terms of GC area (%).

[0204] <GC Analysis Conditions>

[0205] The GC used for the analysis was HP-6890, and the detection was carried out by FID. The chromatographic column was DB-17 (30 m * 0.25 mm * 0.5 μm), the carrier gas was nitrogen (1.0 mL / min), the injection volume was 1 μL, and the column temperature was 80 °C -> 5 °C / min -> 160 °C (8 minutes) -> 20 °C / min -> 280 °C (18 minutes).

[0206] <Content of Unreacted XDA after Salt Formation (%)>

[0207] After the salt formation reaction was completed, a sample was taken, and the remaining XDA content was measured in terms of GC area (%).

[0208] [Experimental Example 3: Analysis of Polyisocyanate Composition]

[0209] For the polyisocyanate compositions prepared in the examples and comparative examples, the color, NCO content, remaining XDI content, and turbidity were measured according to the following method, and the results are shown in Table 2.

[0210] For the above-prepared polyisocyanate composition samples, the color evaluation was carried out by the APHA method at 25 °C.

[0211] [Experimental Example 4: Evaluation of Optical Articles]

[0212] 20.8 g of the reaction mixtures containing different isocyanate compounds prepared in the examples and comparative examples, 0.04 g of zelec UN (produced by Stepan Company), and 0.04 g of biosorb 583 (produced by Sakai Chemical Industry Co., Ltd) were stirred in a flask at room temperature for about 20 minutes. Then, 0.002 g of dibutyltin dichloride was further added and stirred for 10 minutes. Then, 19.2 g of 2,3-bis(2-thioethylthio)propane-1-thiol was added to the mixture, degassed under a pressure of 5 mbar, and stirred for 1 hour to prepare a liquid mixture.

[0213] The liquid mixture was filtered through a 1-μm PTFE filter and injected into a mold composed of a glass mold and tape. This mold was placed in an oven, and the temperature was gradually increased from 10 °C to 120 °C for a polymerization reaction for 20 hours. After the polymerization was completed, the mold was taken out of the oven and demolded to obtain a plastic lens. The obtained plastic lens was annealed at 120 °C for 6 hours to produce the final optical lens sample.

[0214] For the prepared optical lenses, according to the following evaluation criteria, the degree of occurrence of cloudiness (transparency) was visually evaluated under various light source conditions, and the results are shown in Table 2.

[0215] <Evaluation Criteria>

[0216] C (transparent): Transparent under both fluorescent lamp and zirconium lamp

[0217] S.H (slightly hazy): Transparent under fluorescent lamp, but slightly cloudy under zirconium lamp

[0218] L.H (hazy): Transparent under fluorescent lamp, but cloudy under zirconium lamp

[0219] V.H (visibly hazy): Cloudy under both fluorescent lamp and zirconium lamp

[0220] Y.I: Yellowing of the lens

[0221]

Table 2

[0222]

[0223] As shown in Table 1, in the examples, by controlling the purity of the reaction composition and simultaneously controlling the content range of specific low-boiling compounds in the by-products, a simple preparation process can be used to prepare high-purity xylylene diisocyanate compounds in high yield. In addition, by controlling the salt-forming reaction conditions of the amine compound within an appropriate range, high-purity xylylene diisocyanate can be prepared and the process efficiency of the subsequent phosgenation reaction can be improved. Compared with the comparative examples, the optical lenses prepared using this process exhibited excellent transparency. It was also confirmed that even after preparing a polyisocyanate composition using the xylylene diisocyanate prepared according to the above method, the color value measured according to the APHA method was still low.

[0224] In the comparative examples, it was confirmed that with the change of process conditions, the number of impurities increased, or the particle size became uneven after the salt-forming reaction, thus inhibiting the phosgenation reaction. Therefore, compared with the examples, the quality (such as transparency and color) that needs to be considered when applying to the product decreased.

Claims

1. A xylylene diisocyanate composition, comprising: a xylylene diisocyanate compound; and low-boiling compounds comprising isocyanatomethylbenzaldehyde and isocyanatomethylbenzonitrile, Among them, wherein, relative to the total amount of the composition, the content of the low-boiling compounds is 1% or less.

2. The benzene diisocyanate methylene composition according to claim 1, wherein, Relative to the total amount of the composition, the content of the low-boiling compounds is 0.0001% to 0.7%.

3. The benzene diisocyanate methylene composition according to claim 1, wherein Relative to the total amount of the composition, the content of isocyanatomethylbenzaldehyde is 0.0001% to 0.15%.

4. The benzylidene diisocyanate composition according to claim 1, wherein Relative to the total amount of the composition, the content of isocyanatomethylbenzonitrile is 0.0001% to 0.1%.

5. The benzylidene diisocyanate composition according to claim 1, wherein, The low-boiling compounds further comprise chloromethylbenzyl isocyanate.

6. The benzylidene diisocyanate composition according to claim 5, wherein Relative to the total amount of the composition, the content of chloromethylbenzyl isocyanate is 0.01% to 0.2%.

7. A method for preparing a xylylene diisocyanate composition, the method comprising: in a first step, reacting an amine compound with hydrogen chloride at normal pressure at 20°C to 90°C in a solvent to obtain an amine salt compound; in a second step, reacting the amine salt compound with phosgene to obtain a reaction mixture comprising a xylylene diisocyanate compound; and in a third step, removing the solvent and unreacted phosgene from the reaction mixture to prepare a xylylene diisocyanate composition, wherein the solvent is one or more selected from chlorobenzene, 1,2-dichlorobenzene, 1,4-dichlorobenzene, 1,2,3-trichlorobenzene, and 1,2,4-trichlorobenzene, the purity of the amine compound is 99.0% or more, and relative to the total amount of the composition, the xylylene diisocyanate composition comprises 1% or less of low-boiling compounds, and the low-boiling compounds comprise isocyanatomethylbenzaldehyde and isocyanatomethylbenzonitrile.

8. The method according to claim 7, wherein Relative to the total amount of the composition, the content of the low-boiling compounds is 0.0001% to 0.7%.

9. The method according to claim 7, wherein, The low-boiling compounds further comprise chloromethylbenzyl isocyanate.

10. The method according to claim 7, wherein The amine compound is selected from one or more of m-xylylenediamine, p-xylylenediamine, o-xylylenediamine, and their chlorides.

11. The method according to claim 7, wherein, Relative to the total amount of the solvent, the content of the amine compound is 1 wt% to 20 wt%.

12. The method according to claim 7, wherein, The solvent is 1,2-dichlorobenzene.

13. The method according to claim 7, wherein The second step is carried out at 110°C to 160°C.

14. The method according to claim 7, wherein The second step is carried out by introducing the phosgene compound after heating the amine compound in the solvent at 110°C to 140°C.

15. The method according to claim 7, wherein, The second step is carried out by spraying phosgene into a reactor containing the amine salt compound through a mixing injector.

16. The method according to claim 7, wherein, The third step further comprises a purification process after removing the solvent and unreacted phosgene from the reaction mixture.

17. A method for preparing a polyisocyanate composition, the method comprising: in a first step, reacting an amine compound with hydrogen chloride at normal pressure at 20°C to 90°C in a solvent to obtain an amine salt compound; in a second step, reacting the amine salt compound with phosgene to obtain a reaction mixture comprising a xylylene diisocyanate compound; in a third step, removing the solvent and unreacted phosgene from the reaction mixture to prepare a xylylene diisocyanate composition; and In the fourth step, the benzene diisocyanate methylene composition is polymerized with a polyol to synthesize a polyisocyanate compound. Among them, the solvent is one or more selected from chlorobenzene, 1,2-dichlorobenzene, 1,4-dichlorobenzene, 1,2,3-trichlorobenzene, and 1,2,4-trichlorobenzene. The purity of the amine compound is above 99.0%, and Relative to the total amount of the composition, the benzene diisocyanate methylene composition contains 1% or less of low-boiling compounds, and the low-boiling compounds include isocyanomethylbenzaldehyde and isocyanomethylbenzonitrile.

18. The method according to claim 17, wherein, Relative to the total amount of the composition, the content of the low-boiling compound is 0.0001% to 0.7%.

19. The method according to claim 17, wherein, The low-boiling compound also includes chloromethylbenzyl isocyanate.

20. The method according to claim 17, wherein, The polyol is a triol or a mixture of the triol and other polyols.

21. The method according to claim 17, wherein, The polyol includes diethylene glycol, glycerol, trimethylolethane, trimethylolpropane, or a mixture thereof.

22. The method according to claim 17, wherein The second step is carried out in an inert gas atmosphere in a temperature range of 40°C to 100°C.

23. The method according to claim 17, wherein The third step further includes a purification process after removing the solvent and unreacted phosgene from the reaction mixture.

24. A polymerizable composition, which comprises: The benzene diisocyanate methylene composition according to any one of claims 1 to 6; and One or more of i) a compound based on a polyfunctional thiol and ii) a compound based on a polyfunctional episulfide.

25. An optical article, which comprises a polythiourethane polymer prepared from the polymerizable composition according to claim 24.

26. The optical article according to claim 25, wherein, The optical article is an optical lens.

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