Isophorone diisocyanate composition and blocked product thereof

Abstract

The present application relates to an isophorone diisocyanate composition containing 0.002% to 0.200% methylated isophorone diisocyanate (Me-IPDI), and its use. The blocked isocyanate obtained by further blocking the IPDI of the present application has a lower unblocking temperature and unblocking stability.

Description

[Technical Field]

[0001] The examples herein relate to isophorone diisocyanate compositions and blocked products thereof. [Background technology]

[0002] Isophorone diisocyanate (abbreviated as IPDI) is a colorless or pale yellow liquid at room temperature. It is both an aliphatic and alicyclic isocyanate, with lower reactivity and vapor pressure than aromatic isocyanates, and less toxicity than aromatic isocyanates. The absence of a benzene ring in its structure allows it to have excellent weather resistance. It can be used to produce high-quality polyurethane materials, such as polyurethane elastomers, aqueous polyurethane dispersions, and polyurethane UV resins, which have excellent light stability, weather resistance, and mechanical properties. IPDI can also self-polymerize to form multifunctional polyisocyanates. Paints prepared with IPDI dry very quickly, making them extremely useful in automotive refinish coatings. These applications have strict requirements for the composition and impurity content of the IPDI monomer.

[0003] Blocked isocyanates are produced by the reaction of an isocyanate with a blocking agent. The chemical bond formed between the blocking agent and the isocyanate group (NCO) is relatively weak, and under certain conditions, deblocking can occur, releasing free NCO. Therefore, blocked isocyanates are widely used in one-component polyurethane coatings and binders, particularly in automotive and coil coatings. There are many types of blocking agents that can be used to block isocyanate groups. Commonly used blocking agents include phenolic compounds, alcoholic compounds, oxime compounds, β-dicarbonyl compounds, pyrazole compounds, and amide compounds. Oxime compounds, among others, are widely used as isocyanate blocking agents due to their low deblocking temperature. While the deblocking temperature of blocked isocyanates blocked with oxime compounds is relatively low, still around 140°C, prolonged heating during this process can easily cause the isocyanate to yellow, which impacts the application of the product in clear coats and light-colored coatings. For example, U.S. Patent No. 5,504,178, U.S. Patent No. 5,631,339, and European Patent No. 0,829,500 all disclose the use of certain hydrazide structure substances as stabilizers to improve the problem of yellowing caused by heat during product use. While the above patented technologies can improve the color stability of blocked isocyanate products to some extent during storage, they provide very little solution to the problem of color stability during the deblocking process. Summary of the Invention [Problem to be solved by the invention]

[0004] The following is a summary of the subject matter described in detail herein, which is not intended to limit the scope of protection of the claims.

[0005] The examples of the present application provide an isophorone diisocyanate composition that, from the viewpoint of the composition of the isophorone diisocyanate composition itself, reduces the temperature in the deblocking process, thereby solving the problem of yellowing of blocked isophorone diisocyanate products in the deblocking process. [Means for solving the problem]

[0006] The isophorone diisocyanate (IPDI) composition has a mass content of methylated isophorone diisocyanate (Me-IPDI) of 0.002% to 0.200%, preferably 0.005% to 0.075%, and more preferably 0.010% to 0.060%.

[0007] The general structural formula of Me-IPDI is shown below. TIFF2025529418000001.tif3642 (wherein at least one of R1, R2, R3, R4, R5, and R6 is CH3, and the rest are H, and preferably at least one of R1, R3, and R5 is CH3.)

[0008] The structure of the Me-IPDI is more preferably one or more selected from the following structures: TIFF2025529418000002.tif43126

[0009] The method for preparing the isophorone diisocyanate composition described in the present application is not particularly required, and the isophorone diisocyanate composition having such a composition can be obtained in any feasible manner in the related art.

[0010] CN109761855 describes an industry-wide method for preparing isophorone diisocyanate, and the preparation steps of IPDI are as follows: (1) reacting isophorone with hydrogen cyanide in the presence of a catalyst to obtain isophorone nitrile; (2) reacting the isophorone nitrile obtained in step (1), ammonia gas, and hydrogen gas in the presence of a catalyst to obtain isophorone diamine; and (3) phosgenating isophorone diamine to obtain isophorone diisocyanate. According to the process provided in this patent, the production of IPDI requires three key raw materials: isophorone (IP), isophorone nitrile (IPN), and isophorone diamine (IPDA), and three key reaction steps: cyanation, hydrogenation, and phosgenation.

[0011] The formation of Me-IPDA can be controlled by controlling the chloride content in the catalyst during the preparation of IPDA from IPN. Chloride ions are introduced to varying degrees during catalyst production, storage, and use. These chlorides react with metals within the catalyst or during use to form metal chlorides. These chlorides catalyze alkylation side reactions during the preparation of IPDA from IPN, leading to the formation of Me-IPDA.

[0012] As a result of research, the applicant of the present application has found that when the chlorine content in the hydrogenation catalyst is controlled to 0.0002 to 0.0200%, preferably 0.0010 to 0.0150%, and more preferably 0.0020 to 0.0200%, the Me-IPDA content in IPDA obtained in the process of preparing IPDA from IPN can be controlled to 0.002% to 0.200%, preferably 0.005% to 0.075%, and more preferably 0.010% to 0.060%, and that further phosgenation can produce IPDI with a Me-IPDI content of 0.002% to 0.200%, preferably 0.005% to 0.075%, and more preferably 0.010% to 0.060%.

[0013] There may be other methods for controlling Me-IPDA, but this application does not list them all. The above methods may be used in combination or individually, and this application does not limit the method for obtaining the IPDI composition.

[0014] The content of Me-IPDI in the isophorone diisocyanate composition described in the present application can be analyzed by injecting a sample by gas chromatography, and there are no special requirements in the present application. For example, the method used in some specific examples is to dissolve the sample in a solvent (preferably dichloromethane), then inject and analyze the sample by gas chromatography, detect it using a hydrogen ion flame detector (FID), and quantitatively calculate it using the area normalization method.

[0015] The isophorone diisocyanate compositions described herein may be further prepared into blocked products. Blocked products prepared with the IPDI compositions of the present invention have characteristics such as a lower unblocking temperature and stability after unblocking.

[0016] The examples of the present application also provide a method for preparing a blocked isophorone diisocyanate having high storage stability, by contacting an IPDI composition according to the present application with a blocking agent to react with the blocked isophorone diisocyanate.

[0017] As a result of research, the applicant has found that a blocked isocyanate composition prepared using an IPDI composition containing a certain amount of Me-IPDI according to the present invention has a lower unblocking temperature and a significantly lower color number after unblocking.

[0018] The Me-IPDI contained in the IPDI composition has one and / or more methyl groups added to the six-membered ring compared to conventional IPDI. As a result, it is presumed that the bond energy of the blocked structure after the formation of the blocked product is lower, and therefore the temperature required for deblocking is lower. Furthermore, according to the knowledge of those skilled in the art, isocyanate-based products are prone to polymerization when heated at high temperatures for a long period of time, which further leads to an increase in color number. On the other hand, the blocked products formed by the IPDI composition of the present application have a lower deblocking temperature and the increase in color number during the deblocking process is relatively small.

[0019] In theory, blocked products prepared with IPDI compositions containing a higher Me-IPDI content have a lower deblocking temperature. However, actual testing has shown that a higher Me-IPDI content reduces the purity and thermal stability of the IPDI composition, resulting in a significant increase in the number of colors in the product during the deblocking process. Therefore, in this application, the Me-IPDI content in the IPDI composition is limited to 0.002% to 0.200%, preferably 0.005% to 0.075%, and more preferably 0.010% to 0.060%.

[0020] According to the preparation method of the present application, in some examples, the blocking agent is a mixture of one or more compounds selected from an oxime compound, an alcohol compound, a lactam compound, a pyrazole compound, and a β-dicarbonyl compound.

[0021] According to the preparation method of the present application, in a preferred embodiment, the oxime compound is one or more selected from butanone oxime, acetone oxime, formaldehyde oxime, acetaldehyde oxime, and cyclohexanone oxime, more preferably butanone oxime.

[0022] In some examples, the molar amount of the oxime compound accounts for 80 mol % or more (eg, 85 mol %, 88 mol %, 90 mol %, 95 mol %, 100 mol %) of the total molar amount of the blocking agent.

[0023] According to the preparation method of the present application, in some examples, the blocking agent further comprises one or more of an alcohol-based compound, a lactam-based compound, a pyrazole-based compound, and a β-dicarbonyl compound, and preferably, the blocking agent further comprises ε-caprolactam and / or 3,5-dimethylpyrazole; In some examples, the alcohol-based compound may be one or more selected from methanol, ethanol, 2-propanol, n-butanol, sec-butanol, 2-ethyl-1-hexanol, 2-methoxyethanol, 2-ethoxyethanol, and 2-butoxyethanol; the lactam-based compound may be one or more selected from ε-caprolactam, δ-valerolactam, and γ-butyrolactam; the pyrazole-based compound may be one or more selected from pyrazole, 3-methylpyrazole, and 3,5-dimethylpyrazole; and the β-dicarbonyl compound may be one or more selected from dimethyl malonate, diethyl malonate, ethyl acetoacetate, methyl acetoacetate, di-n-propyl malonate, diisopropyl malonate, di-n-butyl malonate, and diisobutyl malonate.

[0024] According to the preparation method of the present application, the ratio of the amount of NCO substance to the amount of blocking agent substance in the IPDI composition is preferably 0.9 to 1:1 (for example, 0.95:1, 0.97:1, 0.99:1, 1:1).

[0025] According to the preparation method of the present application, the reaction process conditions include a reaction temperature of 30 to 120°C (e.g., 40°C, 60°C, 80°C, 100°C, or 110°C). There are no particular limitations on the reaction time in this step. For example, the reaction may be continued with stirring until an NCO characteristic absorption peak is no longer detected in an infrared spectrum, thereby obtaining a blocked isocyanate composition.

[0026] According to the preparation method of the present application, in some examples, a solvent inert to NCO groups is added to the reaction system, In some examples, the solvent is one or more selected from ethyl acetate, butyl acetate, 1-methoxy-2-propyl acetate, 3-methoxy-n-butyl acetate, acetone, butanone, 4-methyl-2-pentanone, cyclohexanone, toluene, xylene, and S100 solvent oil, preferably one or more selected from S100 solvent oil, n-butyl acetate, and 1-methoxy-2-propyl acetate. The amount of the solvent described herein is, for example, based on the amount that can completely dissolve the polyisocyanate and blocking agent in the reaction system.

[0027] According to the preparation method of the present application, in order to further reduce the color of the blocked polyisocyanate composition product, the reaction can be protected with an inert gas, including but not limited to one or more of N, CO, CO, He, and Ar, preferably N. [Effects of the Invention]

[0028] Compared with the prior art, the blocked products prepared with the isophorone diisocyanate compositions according to the examples of the present application have the following beneficial effects: 1. Compared to blocked products prepared with conventional IPDI, blocked products prepared using IPDI compositions according to the examples of the present application have lower unblocking temperatures. 2. During the deblocking process of the blocked product prepared using the IPDI composition according to the examples of the present application, the increase in color number of the product is lower than the increase in color of the blocked product prepared with conventional IPDI.

[0029] Other aspects will become apparent upon reading and understanding the detailed description. DETAILED DESCRIPTION OF THE INVENTION

[0030] The technical solutions of the present application are further illustrated below through specific embodiments. Those skilled in the art should understand that the above examples are only intended to help understand the present application and should not be considered as particularly limiting the present application.

[0031] In the following examples and comparative examples, the main sources of raw materials are as follows: Butanone oxime: purchased from Kohoku Senrin Kako Co., Ltd. S100 solvent oil: purchased from ExxonMobil Chemical Company. Color number of blocked isocyanate compositions: Tested using a BYK colorimeter. The content of methylated isophorone diisocyanate in the isophorone diisocyanate composition can be analyzed by injecting a sample and analyzing it by gas chromatography. The method is to dissolve the sample in dichloromethane, then inject and analyze the sample by gas chromatography, detect it using a hydrogen ion flame detector (FID), and quantitatively calculate it using the area normalization method. The chromatography conditions were as follows: Carrier gas: Purified, dried, high-purity nitrogen gas (purity 99.999% or higher) Combustion gas: Hydrogen gas (purity 99.999% or more), flow rate 40 mL / min Combustion auxiliary gas: Purified and dried air, flow rate 400 mL / min Exhaust gas: Nitrogen gas, flow rate 30 mL / min Column flow rate: 1.06 mL / min Split ratio: 30:1 Column temperature (program temperature): 140°C for 0 min, increase to 220°C at 10°C / min, maintain temperature for 1 min, increase to 260°C at 5°C / min, maintain temperature for 0 min, increase to 280°C at 10°C / min, maintain temperature for 1 min. Inlet temperature: 270℃ Detector temperature: 290℃ Injection volume: 0.2μL The color number index of the blocked isocyanate composition is analyzed using the method described in national standard GB / T605-2006. The turbidity index of the blocked isocyanate composition is analyzed using the method described in national standard GB / T605-2006.

[0032] Example 1 Preparation of IPDI compositions with various Me-IPDI contents Step A: Preparation of an Isophorone Diisocyanate Composition Containing Less than 0.002% Me-IPDI According to the method provided in Chinese Patent Application Publication No. 109761855, IPDI is synthesized in the following steps: (1) Isophorone was fed to a preheater at a rate of 200 kg / h and preheated to the reaction temperature of 120°C. After that, it was fed to the reactor disclosed in Example 1 of Chinese Patent No. 103301799 together with HCN and sodium methoxide as an alkali catalyst in a molar ratio of 2:1:0.003, and reacted under operating conditions at an absolute pressure of 1 MPa for 25 minutes to obtain isophorone nitrile (3-cyano-3,5,5-trimethylcyclohexanone, abbreviated as IPN). (2) The isophoronenitrile obtained above, ammonia gas, and hydrogen gas were reacted in the presence of a catalyst. Specifically, the reaction was as follows. a) The isophoronenitrile obtained in step (1) was reacted with ammonia gas in a tubular reactor at a temperature of 60°C and an absolute pressure of 15 MPa in a molar ratio of ammonia gas to isophoronenitrile of 50:1 to obtain 3-cyano-3,5,5-trimethylcyclohexylimine. b) In the presence of a Raney cobalt hydrogenation catalyst (catalyst space velocity: 1.5 g 3-cyano-3,5,5-trimethylcyclohexanone / (ml catalyst·hour)), hydrogen gas, NH3, and the 3-cyano-3,5,5-trimethylcyclohexylimine obtained in step a) were mixed in a 3% KOH ethanol solution and reacted at a temperature of 80°C and an absolute pressure of 18 MPa to obtain a product containing 3-aminomethyl-3,5,5-trimethylcyclohexylamine (abbreviated as IPDA) and 3-cyano-3,5,5-trimethylcyclohexylamine. In step b), the mass ratio of the KOH ethanol solution to the added isophorone nitrile is 1:600, the molar ratio of NH3 to isophorone nitrile is 50:1, and the molar ratio of hydrogen gas to isophorone nitrile is 80:1. c) In the presence of a Raney cobalt hydrogenation catalyst (catalyst space velocity: 1.8 g 3-cyano-3,5,5-trimethylcyclohexanone / (ml catalyst·hour)), hydrogen gas, NH3, and the product containing 3-aminomethyl-3,5,5-trimethylcyclohexylamine obtained in step b) were mixed in a 3% acetic acid-ethanol solution and reacted at a temperature of 120°C and an absolute pressure of 18 MPa to convert 3-cyano-3,5,5-trimethylcyclohexylamine to 3-aminomethyl-3,5,5-trimethylcyclohexylamine. In step c), the mass ratio of the acetic acid-ethanol solution to the IPN obtained in step 1) is 1:500, the molar ratio of hydrogen gas to the IPN obtained in step 1) is 30:1, and the molar ratio of ammonia gas to the IPN obtained in step a) is 50:1. The chlorine content of the Raney cobalt catalyst used in each step of the above step (2) is 0.0001%. (3) Using the heater described in Example 1 of Chinese Patent Publication No. 105214568, the obtained IPDA was vaporized and heated to 355°C. Under nitrogen gas protection, the resulting mixture was continuously introduced into the reactor together with gaseous phosgene heated to 355°C via separate supply pipes. The reaction was carried out at an absolute pressure of 0.05 MPa and a temperature of 360°C. The IPDA and phosgene feed rates were 800 kg / h and 3000 kg / h, respectively. The resulting mixed gas was rapidly cooled to 100°C using a gas injection absorption device with an o-dichlorobenzene solution, yielding a phosgenation liquid containing the product IPDI. Excess phosgene was removed at 180°C and an absolute pressure of 0.1 MPa, yielding a phosgene-free crude IPDI product. The crude product was then rectified in a rectification column at 0.5 kPa and 150-160°C to obtain an IPDI product with a yield of 95% and a purity of 99.85%, of which the Me-IPDI content (the sum of the contents of formulas I, II, and III, hereinafter the same) was 0.0003% (Sample 1).

[0033] Step B: Preparation of an Isophorone Diisocyanate (IPDI) Composition Having an Me-IPDI Content of Greater than 0.200% Step (2) differs from Step A in that the chlorine content of the catalyst Raney Coval used in each step is 0.025%, the solvent used in each step is methanol, and the content of Me-IPDI in the obtained IPDI is 0.32% (Sample 2).

[0034] Step C: Formulation of IPDI compositions with various Me-IPDI contents The resulting samples 1 and 2 were blended in predetermined proportions to obtain IPDI compositions with various Me-IPDI contents, designated as blend samples 1 to 14. Among these, blend samples 2 to 13 had Me-IPDI contents that met the requirements for the IPDI compositions described herein. The specific Me-IPDI contents in the blended IPDI compositions are shown in Table 1 below.

[0035] [Table 1]

[0036] Example 2 220 kg of the isophorone diisocyanate composition blend sample 2-13 obtained in Example 1 and 100 kg of S100 solvent oil manufactured by ExxonMobil Chemical Corporation were added to a reactor and stirred uniformly. Then, 175 kg of butanone oxime was added, and the reaction temperature was controlled at 60-70°C. The mixture was stirred and reacted until the characteristic NCO absorption peak was no longer detectable in the infrared spectrum. This reaction process was carried out under nitrogen gas protection. Finally, 12 batches of blocked isophorone diisocyanate composition products were obtained, and the color index was tested for each. 600 g of each of the 12 batches of blocked isocyanate composition products obtained was placed in a 1 L three-neck flask and placed in a 120°C oil bath under nitrogen gas protection to deblock the product by heating. Infrared monitoring showed that the NCO characteristic absorption of all samples had stopped increasing after 2 hours, indicating that deblocking of all samples was complete. The color number of the deblocked samples was then tested.

[0037] Comparative Example 1 220 kg of the isophorone diisocyanate composition sample 1 obtained in Example 1, blend sample 1, and 100 kg of S100 solvent oil manufactured by ExxonMobil Chemical Corporation were each added to a reactor and stirred uniformly. Then, 175 kg of butanone oxime was added, and the reaction temperature was controlled at 60-70°C. The mixture was stirred and reacted until the characteristic NCO absorption peak was no longer detectable in the infrared spectrum. This reaction process was carried out under nitrogen gas protection. Finally, two batches of blocked isophorone diisocyanate composition products were obtained, and the color index of each was tested. 600 g of each of the two batches of blocked isocyanate composition products obtained was placed in a 1 L three-neck flask and, under nitrogen gas protection, placed in a 120°C oil bath to deblock by heating. Infrared monitoring showed that the NCO characteristic absorption of all samples had stopped increasing after 2 hours, indicating that deblocking of all samples was complete. The color number of the deblocked samples was then tested.

[0038] Comparative Example 2 220 kg of isophorone diisocyanate composition sample 2 obtained in Example 1, blend sample 14, and 100 kg of S100 solvent oil manufactured by ExxonMobil Chemical Corporation were each added to a reactor and stirred uniformly. Then, 175 kg of butanone oxime was added, and the reaction temperature was controlled at 60-70°C. The mixture was stirred and reacted until the characteristic NCO absorption peak was no longer detectable in the infrared spectrum. This reaction process was carried out under nitrogen gas protection. Finally, two batches of blocked isophorone diisocyanate composition product were obtained, and the color index was tested for each. Two batches of blocked isocyanate composition products, Sample 2 and Blend Sample 14, were each taken in an amount of 600 g and placed in a 1L three-neck flask. Under nitrogen gas protection, the mixture was placed in a 120°C oil bath and deblocked by heating. Infrared monitoring showed that the NCO characteristic absorption of all samples continued to increase after 2 hours, indicating that deblocking of the samples was not yet complete. Infrared monitoring showed that the NCO characteristic absorption of all samples had stopped increasing after 4 hours, indicating that deblocking of all samples was complete. The color numbers of the deblocked samples were then tested. The change in color number during the deblocking process for the 12 batches of samples from Example 2 and the 4 batches from Comparative Examples 1 and 2 is shown in Table 2.

[0039] [Table 2]

[0040] The result data in Table 2 show that the increase in color number during deblocking of the 12 batches of blocked isophorone diisocyanate prepared in Example 2 was significantly lower than that of the 4 batches of the comparative example, indicating that the blocked products prepared using the isophorone diisocyanate composition of the present application have a clear advantage over other products in terms of stability during the deblocking process.

[0041] Although the present application has described the detailed method of the present application through the above examples, the present application is not limited to the above detailed method, that is, it does not mean that the present application must be carried out depending on the above detailed method. It should be understood by those skilled in the art that any improvement to the present application, equivalent substitution of each raw material of the product of the present application, addition of auxiliary ingredients, selection of specific methods, etc. are all included in the protection scope and disclosure scope of the present application.

Claims

1. An isophorone diisocyanate composition having a methylated isophorone diisocyanate (Me-IPDI) content of 0.002 wt % to 0.200 wt %.

2. 2. The isophorone diisocyanate composition according to claim 1, wherein the content of Me-IPDI is 0.005% to 0.075%.

3. The isophorone diisocyanate composition according to claim 2, wherein the content of Me-IPDI is 0.010% to 0.060%.

4. The isophorone diisocyanate composition according to any one of claims 1 to 3, wherein the general structural formula of Me-IPDI is shown below. (where R 1 , R 2 , R 3 , R 4 , R 5 , R 6 At least one of 3 and the rest is H.)

5. R 1 , R 3 , R 5 At least one structure of 3 The isophorone diisocyanate composition according to any one of claims 1 to 4, wherein

6. The isophorone diisocyanate composition according to any one of claims 1 to 5, wherein the structure of the Me-IPDI is one or more selected from the following structures:

7. A method for preparing a blocked isophorone diisocyanate having high storage stability, which is obtained by contacting the isophorone diisocyanate composition according to any one of claims 1 to 6 with a blocking agent and reacting them.

8. The method according to claim 7, wherein the blocking agent is one or a mixture of two or more compounds selected from the group consisting of oxime compounds, alcohol compounds, lactam compounds, pyrazole compounds, and β-dicarbonyl compounds.

9. 9. The preparation method according to claim 8, wherein the oxime compound is one or more selected from butanone oxime, acetone oxime, formaldehyde oxime, acetaldehyde oxime, and cyclohexanone oxime.

10. The preparation method according to any one of claims 7 to 9, wherein the ratio of the molar amount of NCO to the molar amount of blocking agent in the isophorone diisocyanate composition is 0.9 to 1:

1.

11. The method according to any one of claims 7 to 10, wherein the reaction temperature is 30 to 120°C.

12. The reaction is carried out in the absence or presence of a solvent, 12. The method of any one of claims 7 to 11, wherein the solvent is one or more selected from ethyl acetate, butyl acetate, 1-methoxy-2-propyl acetate, 3-methoxy n-butyl acetate, acetone, butanone, 4-methyl-2-pentanone, cyclohexanone, toluene, xylene, and S100 solvent oil.

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