Xylylene diisocyanate composition and application thereof

Abstract

The invention discloses a xylylene diisocyanate composition and application thereof. By controlling the color development index CRI of the xylylene diisocyanate composition, the obtained xylylene diisocyanate composition can be used for preparing optical resin with light ground color and excellent yellowing resistance.

Description

Technical Field

[0001] This invention relates to the field of polyurethane optical resins, and more specifically to phthalimide diisocyanate compositions and their application in optical resins. Background Technology

[0002] With the continuous development of electronic products and daily consumption, the demand for eye protection and eyeglasses has also increased. Statistics show that in the first eight months of 2023, the national eyewear manufacturing industry produced approximately 600 million pairs of finished eyeglasses, basically the same as the previous year, achieving operating revenue of over 30 billion yuan, a year-on-year increase of 5.5%. High-refractive-index optical resin lenses are an important development direction in the eyewear industry, mainly requiring a refractive index of 1.60 or higher. The isocyanate component for preparing eyeglass lenses with a refractive index of 1.67 is mainly phenylene diisocyanate (XDI). The synthesis process of XDI mainly uses m-phenylenediamine as a raw material, first reacting it with HCl to produce hydrochloride, then reacting the generated hydrochloride with phosgene to obtain a crude product, which is subsequently purified through distillation or rectification processes to produce qualified products.

[0003] XDI products involve phosgene in their production process, resulting in the presence of chlorinated impurities. These impurities negatively impact product quality, causing issues such as yellowing of the resin base color. Patent CN115746251A mentions an effective factor of 3.8-5.3 in the isocyanate composition, primarily derived from chlorinated isocyanates, such as monochloro-substituted or dichloro-substituted derivatives. Isocyanate compositions meeting this effective factor range can suppress color gain and yellowing under humid and hot conditions. Patent US5576412A states that isocyanates with hydrolyzed chlorine content less than 300 ppm yield high-quality lens resins. SKC's patent CN108586705A mentions controlling the chlorine content in the XDI composition to 100-1000 ppm, where the chlorine includes at least one of chloride ions and chlorine-based storage stabilizers. Therefore, chlorine content is a crucial indicator.

[0004] However, for isocyanate compositions, besides chlorinated impurities from chlorinated NCO, the initial color number is also a significant factor in causing yellowing. If the initial color number of the monomer XDI is high, it will inevitably have a negative effect on the base color. Meanwhile, organic acid stabilizers or antioxidants are often added to the composition to maintain product quality and facilitate downstream customers purchasing XDI as production feedstock. However, with the passage of time, the deterioration of the monomer and the chromophores inherent in the additives themselves will also affect the base color.

[0005] Patent CN 112300361A mentions that changes in turbidity during monomer storage are a significant indicator of monomer deterioration. Downstream customers and consumers are highly sensitive to the resin's base color, especially with the development of tinted lenses, which places even higher demands on the resin's base color. Although previous patents mentioned the impact of indicators such as hydrolyzed chlorine, chlorine content, and turbidity, these are relatively isolated and lack comprehensive guidance for customer use. Therefore, developing a high-quality diphenylmethylene diisocyanate composition and its application in the field of optical resins is of great significance. Summary of the Invention

[0006] The purpose of this invention is to provide a phthalimide diisocyanate composition and its application in the field of optical resins. By limiting the color development index (CRI) in the phthalimide diisocyanate composition, a phthalimide diisocyanate composition more suitable for optical resin materials is obtained.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A phthalimide diisocyanate composition comprising phthalimide diisocyanate, wherein the composition has a Light Deformation Index (CRI) ranging from 5 to 100, preferably a CRI value of 6 to 30;

[0009] The formula for calculating the color index is as follows:

[0010]

[0011] Where H is the initial color number of the sample (Pt-Co color number, unit: Hazen), |a| is the absolute value of chromaticity a in the Lab color space after the aging test, |b| is the absolute value of chromaticity b in the Lab color space after the aging test, L is the L value in the Lab color space after the aging test, and TC is the thermosensitive chlorine parameter, calculated using the following formula:

[0012] TC (Thermosensitive Chlorine Parameter) = (Intrinsic Chlorine Content - Hydrolyzed Chlorine Content) ÷ Total Chlorine Content × 100

[0013] The intrinsic chlorine content ranges from 15 to 300 ppm, preferably from 20 to 200 ppm; the hydrolyzed chlorine content ranges from 10 to 100 ppm, preferably from 20 to 80 ppm; and the total chlorine content ranges from 100 to 800 ppm, preferably from 150 to 500 ppm.

[0014] The intrinsic chlorine content titration analysis method is as follows: (1) Weigh 10g of sample into a conical flask, add 100ml of ethanol, add a magnetic stir bar, and place it in a preheated oil bath. The oil bath temperature is set to 75℃, and reflux for 1h; (2) Transfer the conical flask from the oil bath to a heatable magnetic stirrer. Set the magnetic stirrer temperature to 50℃ and adjust the speed to 300-500rpm to stir normally; (3) Then add 100ml of distilled water and continue stirring for 30min; (4) After the reaction is completed, place the conical flask at room temperature to cool and then titrate.

[0015] The standard solutions used for titration are silver nitrate solution and sodium chloride solution. Specifically: (1) First, titrate the blank test. Take 100 ml of ethanol and 100 ml of water, and add 10 drops of concentrated nitric acid (mass concentration of 65-68%). After stirring evenly, use a Swiss Metrohm potentiometric titrator to add 2 ml of 0.05 mol / L sodium chloride solution and then start titrating with 0.05 mol / L silver nitrate solution to the endpoint. Record the volume of silver nitrate solution consumed as V0 ml; (2) Titrate the above sample cooled to room temperature. Before titration, add 10 drops of concentrated nitric acid (mass concentration of 65-68%). After stirring evenly, use a potentiometric titrator to add 2 ml of 0.05 mol / L sodium chloride solution and then start titrating with 0.05 mol / L silver nitrate solution to the endpoint. Record the volume of silver nitrate solution consumed as V1 ml.

[0016] Substituting the above data into the following formula: Intrinsic chlorine = (V1 – V0) * 0.05 * 3.546 / sample mass, where the sample mass is in g, the intrinsic chlorine is calculated to be in ppm.

[0017] The titration analysis method for hydrolyzed chlorine content is based on the test method for hydrolyzed chlorine content in isocyanates in the national standard GB12009.2-89, specifically as follows: (1) Weigh 10g of sample into a beaker, add 20ml of acetone and 50ml of methanol in sequence, cover with a watch glass, place the beaker on an electromagnetic stirring plate, adjust the speed to 300-500rpm, set the temperature to 50℃, and stir for 15-20min; (2) Add 150ml of pure water, continue stirring for 30min, and maintain the speed and temperature unchanged; (3) After the reaction is completed, place the beaker at room temperature to cool before titration. Before titration, add 10 drops of concentrated nitric acid (mass concentration of 65-68%).

[0018] The standard solutions used for titration are silver nitrate solution and sodium chloride solution. Specifically: (1) First, titrate the blank test. Take 20 ml of acetone, 50 ml of methanol and 150 ml of water, and add 10 drops of concentrated nitric acid (mass concentration of 65-68%). After stirring evenly, use a Swiss Metrohm potentiometric titrator to add 2 ml of 0.05 mol / L sodium chloride solution and then start titrating with 0.05 mol / L silver nitrate solution to the endpoint. Record the volume of silver nitrate solution consumed as V0 ml; (2) Titrate the above sample cooled to room temperature. Before titration, add 10 drops of concentrated nitric acid. After stirring evenly, use a potentiometric titrator to add 2 ml of 0.05 mol / L sodium chloride solution and then start titrating with 0.05 mol / L silver nitrate solution to the endpoint. Record the volume of silver nitrate solution consumed as V1 ml.

[0019] Substituting the above data into the following formula: Hydrolyzed chlorine content = (V1 – V0) * 0.05 * 3.546 / sample mass, where the sample mass is in g, the intrinsic chlorine is calculated to be in ppm.

[0020] X-ray fluorescence spectrometry analysis of total chlorine content: The test method uses chromatographically pure CCl4 standard as the Cl source and ethyl acetate as the diluent. Cl in the sample is excited by X-rays, generating characteristic X-ray fluorescence. A standard curve is plotted based on the linear relationship between characteristic X-ray fluorescence intensity and elemental concentration. The extrapolated value is the Cl content in the sample. Instrument model: MERAK-LE II.

[0021] To ensure the accuracy of the test results, the intrinsic chlorine content, hydrolyzed chlorine content, and total chlorine content of the same sample were tested multiple times, and the average value was taken.

[0022] Those skilled in the art can control the content of intrinsic chlorine, hydrolyzed chlorine, and total chlorine by controlling reaction conditions and purification methods such as distillation and crystallization.

[0023] Composition aging test: Add 3% aniline by mass to the composition, stir evenly, let stand at room temperature for 1 hour, and then use Hunterlab VISTA colorimeter to test the L, a and b values ​​of the sample.

[0024] Preferably, after aging tests, the composition has an a value in the Lab color space ranging from -10 to 20, preferably from -5 to 15; a b value ranging from 1 to 25, preferably from 1.5 to 20; and an L value ranging from 80 to 100, preferably from 90 to 99.99.

[0025] The initial color number H of the composition sample ranges from 2 to 40 Hazen, preferably from 3 to 20 Hazen.

[0026] Preferably, in the phthalimide diisocyanate composition, the mass content of isophthalimide diisocyanate is 95-100 wt%, and more preferably, the mass content of isophthalimide diisocyanate is 97-99.99%. The above content can be quantitatively analyzed using gas chromatography.

[0027] The present invention also provides an application of a phthalimide diisocyanate composition for the preparation of optical resins.

[0028] A method for preparing an optical resin involves uniformly mixing a phenylenediamine diisocyanate composition, a polythiol compound, and a catalyst, followed by heating and reaction to prepare the optical resin.

[0029] The polythiol compound is selected from one or more combinations of polythiol compounds containing at least two thiol functional groups.

[0030] Preferably, the polythiol compound is selected from one or a combination of two or more of the following: ethylene glycol dimercaptoacetate, 1,2-bis(2-mercaptoethoxy)ethane, di(mercaptoacetic acid)-1,4-butanediol, trimethylolpropane tris(3-mercaptopropionate), trimethylolpropane tris(2-mercaptoacetate), pentaerythritol tetramercaptoacetate, 4,8-bis(mercaptomethyl)-3,6,9-trithiaundecane-1,11-dithiol, 2,3-dithio(2-mercapto)-1-propanethiol, and pentaerythritol tetra(3-mercaptopropionic acid) ester, preferably one or a combination of two of 2,3-dithio(2-mercapto)-1-propanethiol and pentaerythritol tetra(3-mercaptopropionic acid) ester.

[0031] To enhance the reactivity of the functional groups, the molar ratio of NCO groups to SH groups in the polythiol compound in the dimethyl phthalate diisocyanate composition is 0.8-1.5, preferably 0.9-1.1.

[0032] The catalyst is a commonly used organometallic catalyst for the NCO and SH reactions, including metal carboxylates and metal alkyl compounds, wherein the metal elements are mainly tin, potassium, lead, mercury, and zinc, with tin metals being preferred. Specific examples include dialkyltin halides such as dibutyltin dichloride and dimethyltin dichloride, and dialkyltin dicarboxylates such as dimethyltin diacetate, dibutyltin dioctanoate, and dibutyltin dilaurate, with dibutyltin dichloride being preferred. Based on the total mass of the isocyanate composition and polythiol compound, the amount of catalyst added can be 0.01-1.0% by weight, preferably 0.02-0.5% by weight.

[0033] In the preparation method of the optical resin, commonly used additives in the art, such as ultraviolet absorbers and release agents, may also be added. For example, the ultraviolet absorber is selected from benzophenones, triazines, and benzotriazoles, preferably benzotriazoles; the benzotriazole ultraviolet absorber specifically includes UV49, UV326, UV327, UV360, UV380, and UV329, preferably UV329 (trade name Tinuvin 329). Based on the total mass of the phthalimide diisocyanate composition and polythiol compounds, the amount of ultraviolet absorber added can be from 0.01 to 2.0% by weight. The release agent is a phosphate ester-based release agent, such as Zelc UN (manufactured by Sigma-Aldrich or Stepan), and based on the total mass of the phthalimide diisocyanate composition and polythiol compounds, the amount of release agent added can be from 0.01 to 2.0% by weight.

[0034] In this invention, the reaction between isocyanate and polythiol compound is well known in the art and is not limited herein.

[0035] In some preferred embodiments of the present invention, the preparation process mainly includes stirring and mixing the components in the raw material composition, followed by degassing and curing to obtain the polyurethane optical resin. The curing process requires slowly heating from a low temperature to a high temperature, for example, from room temperature to 100-120°C at a programmed rate of 0.1-0.3°C / min, to polymerize and cure it, and then maintaining it at 120-130°C for 2-3 hours to achieve secondary curing. After cooling to room temperature, it is then demolded to obtain the optical material.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] This invention, through studying parameters affecting the base color of resin, discovered that when the color development index of the XDI composition is controlled within the range described in this invention, the optical resin prepared exhibits superior performance. The thermosensitive chlorine parameter indicates the effect of chlorine on the base color of the resin during high-temperature heating processing. The parameter ln[10000×(|a|+|b|) / L] reflects the effect on the base color of the resin due to accelerated aging caused by aniline organic base and additives present in the composition. By comprehensively limiting the above parameters, an XDI composition suitable for optical resins can be obtained, achieving a light base color and resistance to yellowing. Attached Figure Description

[0038] Figure 1 Graphs showing the changes in yellowing properties of optical resins prepared from phthalimide diisocyanate compositions with different CRI values ​​involved in Examples 1-6 and Comparative Example 1. Detailed Implementation

[0039] The present invention is further illustrated by the following embodiments, but the scope of protection of the present invention is not limited.

[0040] The following embodiments of the present invention will be analyzed and characterized using the instruments described below.

[0041] 1. GC Analysis: The content of intermediate-phthalimide diisocyanate in the phthalimide diisocyanate composition was quantitatively determined by gas chromatography (Agilent 8890B). The analytical column was DB-5 (30m*320μm*0.25μm), the gas chromatography injection volume was 0.5μL, the split ratio was 1 / 30, the injection port temperature was 280℃, the column flow rate was 1mL / min, the FID detector temperature was 280℃, the hydrogen flow rate was 40mL / min, and the air flow rate was 400mL / min. The gas chromatography temperature program was as follows: starting from 50℃ and holding for 2 min, then increasing the temperature at 5℃ / min to 80℃, and then increasing it at 15℃ / min to 280℃, for a total duration of 31.3 min.

[0042] 2. Initial sample color number test: The test was conducted at room temperature (25℃) using the VISTA colorimeter from Hunterlab Instruments Co., Ltd. Specifically: (1) After turning on the instrument, a blank calibration was performed using pure water, and a 20mm cuvette was selected. (2) The sample was added to a 20mm quartz cuvette, the color number was tested, and the data was recorded in hazen.

[0043] 3. The intrinsic chlorine content titration analysis method is as follows: (1) Weigh 10g of sample into a conical flask, add 100ml of ethanol, add a magnetic stir bar and place it in a preheated oil bath. The oil bath temperature is set to 75℃ and reflux for 1h; (2) Transfer the conical flask from the oil bath to a heatable magnetic stirrer. Set the magnetic stirrer temperature to 50℃ and adjust the speed to 300-500rpm to make it stir normally; (3) Then add 100ml of distilled water and continue stirring for 30min; (4) After the reaction is completed, place the conical flask at room temperature to cool and then titrate. Before titration, add 10 drops of concentrated nitric acid (mass concentration of 65-68%).

[0044] The standard solutions used for titration are silver nitrate solution and sodium chloride solution. Specifically: (1) First, titrate the blank test. Take 100 ml of ethanol and 100 ml of water, and add 10 drops of concentrated nitric acid. After stirring evenly, use a Swiss Metrohm potentiometric titrator to add 2 ml of 0.05 mol / L sodium chloride solution and then start titrating with 0.05 mol / L silver nitrate solution to the endpoint. Record the volume of silver nitrate solution consumed as V0 ml; (2) Titrate the above sample cooled to room temperature. Before titration, add 10 drops of concentrated nitric acid. After stirring evenly, use a potentiometric titrator to add 2 ml of 0.05 mol / L sodium chloride solution and then start titrating with 0.05 mol / L silver nitrate solution to the endpoint. Record the volume of silver nitrate solution consumed as V1 ml.

[0045] Substituting the above data into the following formula: Intrinsic chlorine = (V1 – V0) * 0.05 * 3.546 / sample mass, where the sample mass is in g, the intrinsic chlorine is calculated to be in ppm.

[0046] 4. The titration analysis method for hydrolyzed chlorine content is based on the test method for hydrolyzed chlorine content in isocyanates in the national standard GB12009.2-89, specifically as follows: (1) Weigh 10g of sample into a beaker, add 20ml of acetone and 50ml of methanol in sequence, cover with a watch glass, place the beaker on an electromagnetic stirring plate, adjust the speed to 300-500rpm, set the temperature to 50℃, and stir for 10-20min; (2) Add 150ml of pure water, continue stirring for 30min, and maintain the speed and temperature unchanged; (3) After the reaction is completed, place the beaker at room temperature to cool before titration. Before titration, add 10 drops of concentrated nitric acid (mass concentration of 65-68%).

[0047] The standard solutions used for titration are silver nitrate solution and sodium chloride solution. Specifically: (1) First, titrate the blank test. Take 20 ml of acetone, 50 ml of methanol and 150 ml of water, and add 10 drops of concentrated nitric acid. After stirring evenly, use a Swiss Metrohm potentiometric titrator to add 2 ml of 0.05 mol / L sodium chloride solution and then start titrating with 0.05 mol / L silver nitrate solution to the endpoint. Record the volume of silver nitrate solution consumed as V0 ml; (2) Titrate the above sample cooled to room temperature. Before titration, add 10 drops of concentrated nitric acid. After stirring evenly, use a potentiometric titrator to add 2 ml of 0.05 mol / L sodium chloride solution and then start titrating with 0.05 mol / L silver nitrate solution to the endpoint. Record the volume of silver nitrate solution consumed as V1 ml.

[0048] Substituting the above data into the following formula: Hydrolyzed chlorine content = (V1 – V0) * 0.05 * 3.546 / sample mass, where the sample mass is in g, the intrinsic chlorine is calculated to be in ppm.

[0049] 5. X-ray fluorescence spectroscopy method for total chlorine content testing: Using chromatographically pure CCl4 standard as the chlorine source and ethyl acetate as the diluent, the chlorine element in the sample is excited by X-rays, generating characteristic X-ray fluorescence. A standard curve is plotted based on the linear relationship between the characteristic X-ray fluorescence intensity and the element concentration. The extrapolated value is the chlorine content in the sample. Instrument model: MERAK-LE II.

[0050] To ensure the accuracy of the results for intrinsic chlorine, hydrolyzed chlorine, and total chlorine, the same sample was tested three times, and the average value was taken.

[0051] The mass concentration of concentrated nitric acid is 65-68%.

[0052] 6. Composition aging test: Add 3% aniline by mass to the composition, stir evenly, and let stand at room temperature for 1 hour. Then use Hunterlab VISTA colorimeter to test the L, a and b values ​​of the sample, and calculate the possible stability parameters by substituting them into the following formula.

[0053] Stability parameter = ln[10000×(|a|+|b|) / L]

[0054] 7. Optical Resin Application Index Analysis: The light transmittance was measured using a Hunterlab USVIS1839 colorimeter, with a C / 2 light source as the test light source, and the test mode was total transmittance. The yellowness index (YI value) of the test sample was also measured.

[0055] 8. Resin aging test: The resin YI value was tested again after being irradiated with a composite ultraviolet light of wavelengths of 254nm and 365nm (model WFH-204B, Shanghai Jingke Industrial Co., Ltd.) for a total of 48 hours.

[0056] The optical resins prepared using the dimethyl phthalate composition and polythiol composition in the following examples were all prepared by a fixed mold (the fixed mold is a flat-bottomed glass cup with a bottom diameter of 500 mm and a height of 800 mm), and the height of the mixture in the mold before curing was 7 mm.

[0057] The main raw materials are: m-phenylenediamine (Shanghai Taihe, purity ≥95%), the polythiol compound selected is 2,3-dithio(2-mercapto)-1-propanethiol (purity ≥96%, Shandong Yifeng), the catalyst is dibutyltin dichloride (DBC, purity 96%, Sigma-Aldrich), the internal release agent (trade name Zelec UN, Sigma-Aldrich, purity 98%), the ultraviolet absorber UV-329 (trade name TINUVIN 329, purity 98%, Shanghai Aladdin Biochemical Technology Co., Ltd.), and the three commercially available XDIs were purchased from TCI, aldaddin and Kaiwei Chemical, respectively.

[0058] In the following examples, the different samples are, on the one hand, commercially available products, and on the other hand, obtained by salt formation photochemical reaction of amines as raw materials, and are mainly prepared by changing the process parameters of salt formation photochemical reaction or adjusting the distillation process parameters.

[0059] Example 1

[0060] Preparation of phenylenediamine diisocyanate composition: 40g of m-phenylenediamine and 500g of o-dichlorobenzene solvent were added to a 1L three-necked flask. HCl gas was introduced into the flask at a rate of 3L / min while maintaining the temperature at 10-30℃ to induce a salt formation reaction, yielding a milky white hydrochloride. The system was then heated to 160℃, and phosgene was introduced at a rate of 2L / min until the reaction solution became clear. Nitrogen gas was then introduced to remove excess phosgene, and the solution was further distilled to obtain the crude product. The crude product was purified using a glass distillation column. The crude product was preheated to 120℃, then fed into the column, maintaining a bottom temperature of 155℃, a top temperature of 125℃, a reflux ratio of 10:1, and an operating pressure of 100Pa at the top. The desired product was then collected from the top of the column, filtered through a 1μm PTFE membrane, and the sample color was recorded in Table 1.

[0061] GC analysis: Weigh 0.06 g of sample and 1.5 ml of dichloromethane into a 2 ml sample vial, cap the vial, shake well, and perform gas chromatography analysis. The purity of m-phenylenedimethyl diisocyanate was recorded in Table 1 using the area normalization method.

[0062] Composition aging test: Add 3% aniline by mass to the product, stir evenly, let stand at room temperature for 1 hour, and then use Hunterlab VISTA colorimeter to test the L, a and b values ​​of the sample and record them in Table 1.

[0063] The intrinsic chlorine, hydrolyzed chlorine, and total chlorine content were determined.

[0064] The CRI value can be calculated using the formula to be 89.70.

[0065] Application Evaluation and Testing: 52g of phenylenediamine diisocyanate composition was weighed into a stirred reaction vessel, and 0.02g of dibutyltin dichloride catalyst, 0.05g of UV absorber UV-329, and 0.2g of internal release agent were added sequentially. After dissolution, 48g of 2,3-dithio(2-mercapto)-1-propanethiol was added. After stirring, the mixture was filtered through a filter membrane and injected into a lens processing mold (the liquid level in the mold was approximately 7mm). Degassing was carried out for 1 hour at 25℃ and ≤2kPa. The filter membrane had a pore size of 1μm. After degassing, the mixture was heated in an oven from 25℃ to 120℃ at a rate of 0.2℃ / min to polymerize and cure. When the oven temperature reached 120℃, it was maintained for 2 hours to obtain a cured sample. The sample was then allowed to cool naturally to room temperature and cured a second time at room temperature for 48 hours before demolding to obtain the optical resin material. After demolding, the obtained optical resin material is subjected to subsequent initial optical YI value analysis.

[0066] The resin YI value was tested after being irradiated with a composite ultraviolet light of wavelengths 254nm and 365nm (model WFH-204B, Shanghai Jingke Industrial Co., Ltd.) for a cumulative period of 48 hours.

[0067] Example 2

[0068] Preparation of phenyl dimethyl diisocyanate composition: The process is the same as in Example 1, except that the distillation reflux ratio is changed to 20:1.

[0069] Analytical testing: GC analysis, composition aging test, intrinsic chlorine and hydrolytic chlorine titration analysis, and total chlorine test were performed in the same manner as in Example 1, and the test results were recorded in Table 1. The CRI value was calculated to be 25.11 using the formula.

[0070] Application evaluation: The same resin synthesis and aging experiments were conducted as in Example 1, and the test results are recorded in Table 1.

[0071] Example 3

[0072] Preparation of phenyl dimethyl diisocyanate composition: The process is the same as in Example 1, except that the distillation reflux ratio is changed to 30:1.

[0073] Analytical testing: GC analysis, composition aging test, intrinsic chlorine and hydrolytic chlorine titration analysis, and total chlorine test were performed in the same manner as in Example 1, and the test results were recorded in Table 1. The CRI value was calculated to be 6.83 using the formula.

[0074] Application evaluation: The same resin synthesis and aging experiments were conducted as in Example 1, and the test results are recorded in Table 1.

[0075] Example 4

[0076] The phenylene diisocyanate composition used in this embodiment is a commercially available product from TCI Corporation, and it was filtered through a 1μm PTFE membrane for subsequent experiments.

[0077] Analytical testing: GC analysis, composition aging test, intrinsic chlorine and hydrolytic chlorine titration analysis, and total chlorine test were performed in the same manner as in Example 1, and the test results were recorded in Table 1. The CRI value was calculated to be 20.32 using the formula.

[0078] Application evaluation: The same resin synthesis and aging experiments were conducted as in Example 1, and the test results are recorded in Table 1.

[0079] Example 5

[0080] The phenylene diisocyanate composition used in this embodiment is a commercially available product from Aladdin, and was filtered through a 1μm PTFE membrane for subsequent experiments.

[0081] Gas analysis tests: GC analysis, composition aging test, intrinsic chlorine and hydrolytic chlorine titration analysis, and total chlorine test were performed in the same manner as in Example 1, and the test results were recorded in Table 1. The CRI value was calculated to be 40.07 using the formula.

[0082] Application evaluation: The same resin synthesis and aging experiments were conducted as in Example 1, and the test results are recorded in Table 1.

[0083] Example 6

[0084] The phenylene diisocyanate composition used in this embodiment is a commercially available product from Kevlar Chemical Company. It was filtered through a 1μm PTFE membrane for subsequent experiments.

[0085] Gas analysis tests: GC analysis, composition aging test, intrinsic chlorine and hydrolytic chlorine titration analysis, and total chlorine test were performed in the same manner as in Example 1, and the test results were recorded in Table 1. The CRI value was calculated to be 60.53 using the formula.

[0086] Application evaluation: The same resin synthesis and aging experiments were conducted as in Example 1, and the test results are recorded in Table 1.

[0087] Comparative Example 1

[0088] Preparation of phenyl dimethyl diisocyanate composition: The process is the same as in Example 1, except that the distillation reflux ratio is changed to 5:1 and PTFE membrane filtration is not used.

[0089] Analytical testing: GC analysis, composition aging test, intrinsic chlorine and hydrolytic chlorine titration analysis, and total chlorine test were performed in the same manner as in Example 1, and the test results were recorded in Table 1. The CRI value was calculated to be 116.07 using the formula.

[0090] Application evaluation: The same resin synthesis and aging experiments were conducted as in Example 1, and the test results are recorded in Table 1.

[0091] Comparative Example 2

[0092] Preparation of phenyl dimethyl diisocyanate composition: The sample from Example 2 was subjected to a second distillation at a reflux ratio of 20:1.

[0093] Analytical testing: GC analysis, composition aging test, intrinsic chlorine and hydrolytic chlorine titration analysis, and total chlorine test were performed in the same manner as in Example 1, and the test results were recorded in Table 1. The CRI value was calculated to be 3.83 using the formula.

[0094] Application Evaluation: The same resin synthesis was carried out as in Example 1. During the synthesis process, the sample became foggy and not transparent, making it impossible to conduct subsequent tests.

[0095] Table 1. Summary of Sample Testing and Resin Performance Evaluation for Examples 1-6 and Comparative Examples 1-2

[0096]

[0097]

[0098] Plotting initial and aged YI data from Examples 1-6 and Comparative Example 1 Figure 1 .

[0099] Based on the results of Examples 1-6, it can be seen that the CRI value prepared by the present invention can effectively screen high-quality dimethyl phthalate diisocyanate compositions.

[0100] As can be seen from Comparative Examples 1 and 2, when the CRI is too high, the resin yellows severely and the base color is dark. When the CRI is too low, its curing performance is very poor, the resin is foggy and cloudy, and the appearance is not bright, making it unsuitable for use as an optical resin.

[0101] The embodiments described above are some, but not all, embodiments of the present invention. Those skilled in the art, guided by this specification, can make modifications or adjustments to the present invention. These modifications or adjustments should also be within the scope defined by the claims of the present invention.

Claims

1. A xylylene diisocyanate composition comprising a xylylene diisocyanate, characterized in that, The composition has a color rendering index CRI of 5-100, preferably, the CRI value is 6-30; The formula for calculating the color rendering index is as follows: Wherein H is the initial color number of the sample (Pt-Co color number, unit Hazen), |a| is the absolute value of a chroma in the color space Lab value of the sample after the aging test, |b| is the absolute value of b chroma in the color space Lab value of the sample after the aging test, L is the L value in the color space Lab value of the sample after the aging test, and TC is the heat-sensitive chlorine parameter; Preferably, the heat-sensitive chlorine parameter TC value is calculated by the following formula: TC = (intrinsic chlorine content-hydrolytic chlorine content) ÷ total chlorine content × 100.

2. The composition according to claim 1, wherein, The intrinsic chlorine content is in the range of 15-300 ppm, preferably 20-200 ppm, the hydrolytic chlorine content is in the range of 10-100 ppm, preferably 20-80 ppm, and the total chlorine content is in the range of 100-800 ppm, preferably 150-500 ppm.

3. The composition according to claim 1 or 2, characterized in that, The initial color number H of the sample is in the range of 2-40 Hazen, preferably 3-20 Hazen.

4. The composition according to claim 1 or 2, characterized in that, After the aging test, the a value in the color space Lab value of the composition sample is in the range of -10-20, preferably -5-15; the b value is in the range of 1-25, preferably 1.5-20; and the L value is in the range of 80-100, preferably 90-99.

99.

5. The composition according to any one of claims 1 to 3, characterized in that, The mass content of m-xylylene diisocyanate in the m-xylylene diisocyanate composition is 95-100 wt%, preferably, the mass content of m-xylylene diisocyanate is 97-99.99%.

6. A method for producing an optical resin, characterized by, The m-xylylene diisocyanate composition, the polysulfane compound and the catalyst according to any one of claims 1-5 are mixed uniformly to prepare an optical resin by reaction; The polysulfane compound is selected from one or more of polysulfane compounds containing at least two thiol functional groups; Preferably, the polysulfane compound is selected from one or a combination of two or more of dimercaptoacetic acid ethylene glycol ester, 1,2-bis(2-mercaptoethoxy)ethane, di(mercaptoacetic acid)-1,4-butanediol ester, trimethylolpropane tri(3-mercaptopropionate), trimethylolpropane tri(2-mercaptoacetate), pentaerythritol tetra-mercaptoacetate, 4,8-bis(mercapto-methyl)-3,6,9-trithiaundecane-1,11-dithiol, 2,3-dithio(2-mercapto)-1-propane thiol, and pentaerythritol tetra(3-mercaptopropionate), preferably one or a combination of 2,3-dithio(2-mercapto)-1-propane thiol and pentaerythritol tetra(3-mercaptopropionate).

7. The production method according to claim 6, wherein The molar ratio of NCO groups in the m-xylylene diisocyanate composition to SH groups in the polysulfane compound is 0.8-1.5, preferably 0.9-1.1; Preferably, the catalyst is an organometallic catalyst, including carboxylate, metal alkyl compound, wherein the metal element includes tin, potassium, lead, mercury, zinc, preferably tin metal. Preferably, the catalyst is selected from one or more of dibutyltin dichloride, dimethyltin dichloride, dimethyltin diacetate, dibutyltin dioctate, dibutyltin dilaurate; Preferably, the catalyst is added in an amount of 0.01 to 1% by weight, preferably 0.02 to 0.5% by weight, based on the total mass of the xylylene diisocyanate composition and the polythiol compound.

8. The production method according to claim 6 or 7, characterized by, In the method of preparing the optical resin, an ultraviolet absorber and a release agent are further added.

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