An isophorone diisocyanate composition and its blocked product

Abstract

The present invention relates to an isophorone diisocyanate composition and an application thereof, wherein the content of methylated isophorone diisocyanate (Me-IPDI) in the isophorone diisocyanate composition is 0.002%-0.200%. The blocked isocyanate obtained by further blocking the IPDI provided by the present invention has a lower unblocking temperature and unblocking stability.

Description

Technical Field

[0001] The invention provides an isophorone diisocyanate composition and a blocked product thereof. Background Art

[0002] Isophorone diisocyanate (IPDI for short) is a colorless or light yellow liquid at room temperature. It is an aliphatic isocyanate and also an alicyclic isocyanate. It has lower reactivity and vapor pressure than aromatic isocyanates, and is less toxic than isocyanates. Since there is no benzene ring in its structure, it has excellent weather resistance and can be used to prepare high-grade polyurethane materials with light stability, weather resistance and excellent mechanical properties, such as elastomers, waterborne polyurethane dispersions, UV resins, etc. IPDI can also self-polymerize to generate multifunctional polyisocyanates. The surface of the coating prepared with it dries very quickly, and it has excellent application in automotive repair paint. In the above applications, the various components and impurity content in the IPDI monomer are strictly required.

[0003] Blocked isocyanates are generated by the reaction of isocyanates with blocking agents. The chemical bond formed by the blocking agent and NCO is relatively weak, and it can be unblocked and release free NCO under certain conditions. Therefore, blocked isocyanates are widely used in one-component polyurethane coatings and adhesives, especially for automotive coatings and coil coatings. There are many types of blocking agents that can be used for isocyanate groups. Currently, the commonly used blocking agents include phenolic compounds, alcohol compounds, oxime compounds, β-dicarbonyl compounds, pyrazole compounds, amide compounds, etc. Among them, oxime compounds are widely used as isocyanate blocking agents because of their low unblocking temperature. Although the unblocking temperature of blocked isocyanates blocked by oxime compounds is relatively low, it is still around 140°C. Long-term heating in this process can easily cause the isocyanate to turn yellow, thereby affecting the application of the product in clear paint and light-colored paint. For example, patent documents US5504178, US5631339, and EP0829500 all disclose the use of some hydrazinoacyl-structured substances as stabilizers to improve the thermal yellowing problem that occurs during product application. Although the above patented technologies can improve the color stability of blocked isocyanate products during storage, there are few solutions to the color stability problem during the unblocking process. Summary of the invention

[0004] In view of the above problems existing in the prior art, the object of the present invention is to develop an isophorone diisocyanate composition, which reduces the temperature of the unblocking process from the perspective of the composition of the isophorone diisocyanate composition itself, thereby solving the problem of yellowing of the blocked isophorone diisocyanate product during the unblocking process.

[0005] To achieve the above object, the present invention adopts the following technical solution:

[0006] An isophorone dicyanate (IPDI) composition, wherein the mass content of methylated isophorone diisocyanate (Me-IPDI) is 0.002%-0.200%, preferably 0.005%-0.075%, and more preferably 0.010%-0.060%.

[0007] The general structural formula of the Me-IPDI is:

[0008]

[0009] wherein at least one of R1, R2, R3, R4, R5, and R6 is CH3, and the rest are H, preferably at least one of R1, R3, and R5 is CH3;

[0010] The structure of the Me-IPDI is more preferably one and / or more of the following structures:

[0011]

[0012] There is no specific requirement for the preparation method of the isophorone dicyanate composition of the present invention, and the isophorone dicyanate composition of the composition can be obtained by any achievable method in the prior art.

[0013] Patent CN109761855A mentions a method for preparing isophorone diisocyanate in the entire industrial chain. The preparation process of IPDI is as follows: (1) in the presence of a catalyst, isophorone reacts with hydrogen cyanide to obtain isophorone nitrile; (2) the isophorone nitrile obtained in step (1), ammonia and hydrogen react in the presence of a catalyst to obtain isophorone diamine; (3) isophorone diamine is subjected to phosgenation to obtain isophorone diisocyanate. According to the process provided by this patent, IPDI uses three key raw materials, isophorone (IP), isophorone nitrile (IPN), and isophorone diamine (IPDA), and three key reaction steps, cyanation, hydrogenation, and phosgenation, in the production process.

[0014] The production of Me-IPDA can be controlled by controlling the chloride content in the catalyst in the process of preparing IPDA from IPN. During the production, storage or use of the catalyst, more or less chloride ions will be introduced, which will react with the metal inside the catalyst or during use to form metal chlorides. Such chlorides catalyze the alkylation side reaction in the process of preparing IPDA from IPN, thereby leading to the production of Me-IPDA.

[0015] The inventors of the present invention have found through research that when the chlorine content in the hydrogenation catalyst is controlled to 0.0002%-0.0200%, preferably 0.0010%-0.0150%, and more preferably 0.0020%-0.0200%, the Me-IPDA content in the IPDA obtained in the IPN preparation of IPDA process can be controlled to 0.002%-0.200%, preferably 0.005%-0.075%, and more preferably 0.010%-0.060%, and further phosgenation can obtain IPDI with a Me-IPDI content of 0.002%-0.200%, preferably 0.005%-0.075%, and more preferably 0.010%-0.060%.

[0016] There may be other methods for controlling Me-IPDA, which are not listed one by one in the present invention. The above methods can be used in combination or alone, and the present invention does not limit the method for obtaining the IPDI composition.

[0017] The content of Me-IPDI in the isophorone diisocyanate composition of the present invention can be analyzed by gas chromatography, and the present invention has no specific requirements. For example, the method used in some specific examples is:

[0018] The sample is dissolved in a solvent (preferably dichloromethane) and then analyzed by gas chromatography, detected by a hydrogen ion flame detector (FID), and quantitatively calculated by an area normalization method.

[0019] The isophorone diisocyanate composition of the present invention can be further prepared into a blocked product. The blocked product prepared by the IPDI composition provided by the present invention has the characteristics of lower unblocking temperature and stable product after unblocking.

[0020] The present invention also provides a method for preparing a storage-stable blocked isophorone diisocyanate, wherein the IPDI composition provided by the present invention is contacted with a blocking agent for reaction to obtain the blocked isophorone diisocyanate.

[0021] According to the research of the present inventors, it is found that the blocked isocyanate composition prepared by using the IPDI composition containing a certain amount of Me-IPDI provided by the present invention has a lower unblocking temperature and a significantly lower color number after unblocking.

[0022] It is speculated that the Me-IPDI contained in the IPDI composition has one and / or more methyl groups on the six-membered ring compared to conventional IPDI, resulting in a lower bond energy of the closed structure after the closed product is formed, and therefore the temperature required for unblocking is lower. In addition, according to the knowledge of those skilled in the art, isocyanate products are prone to polymerization under long-term high-temperature heating, which leads to an increase in color number, while the closed product formed by the IPDI composition provided by the present invention has a lower unblocking temperature, and the color number increase during the unblocking process is relatively small.

[0023] Although in theory, the closed product prepared from the IPDI composition with a higher Me-IPDI content also has a lower unsealing temperature, it is found in the actual test process that when the Me-IPDI content is high, the purity of the IPDI composition also decreases, and its thermal stability also decreases, so the color number of the product during the unsealing process will also increase significantly. Therefore, the present invention limits the Me-IPDI content in the IPDI composition to 0.002%-0.200%, preferably 0.005%-0.075%, and more preferably 0.010%-0.060%.

[0024] According to the preparation method provided by the present invention, in some examples, the blocking agent is a mixture of one or more selected from oxime compounds, alcohol compounds, lactam compounds, pyrazole compounds, and β-dicarbonyl compounds;

[0025] According to the preparation method provided by the present invention, in a preferred embodiment, the oxime compound is selected from one or more of butanone oxime, acetone oxime, formaldehyde oxime, acetaldehyde oxime and cyclohexanone oxime, more preferably butanone oxime.

[0026] In some examples, the molar content of the oxime compound accounts for 80 mol% or more of the total molar amount of the blocking agent (e.g., 85 mol%, 88 mol%, 90 mol%, 95 mol%, 100 mol%);

[0027] According to the preparation method provided by the present invention, in some examples, the blocking agent further comprises one or more of an alcohol compound, a lactam compound, a pyrazole compound and a β-dicarbonyl compound; preferably, the blocking agent further comprises ε-caprolactam and / or 3,5-dimethylpyrazole;

[0028] In some examples, the alcohol compound can be selected from one or more of methanol, ethanol, 2-propanol, n-butanol, sec-butanol, 2-ethyl-1-hexanol, 2-methoxyethanol, 2-ethoxyethanol and 2-butoxyethanol; the lactam compound can be selected from one or more of ε-caprolactam, δ-valerolactam and γ-butyrolactam; the pyrazole compound can be selected from one or more of pyrazole, 3-methylpyrazole and 3,5-dimethylpyrazole; the β-dicarbonyl compound can be selected from one or more of dimethyl malonate, diethyl malonate, ethyl acetoacetate, methyl acetoacetate, di-n-propyl malonate, diisopropyl malonate, di-n-butyl malonate and diisobutyl malonate.

[0029] According to the preparation method provided by the present invention, preferably, the ratio of the amount of NCO substance to the amount of blocking agent substance in the IPDI composition is 0.9-1:1 (for example, 0.95:1, 0.97:1, 0.99:1, 1:1).

[0030] According to the preparation method provided by the present invention, the process conditions of the reaction include: the reaction temperature is 30-120° C. (for example, 40° C., 60° C., 80° C., 100° C., 110° C.). There is no particular regulation on the reaction time in this step, for example, the reaction is carried out under stirring until the NCO characteristic absorption peak is no longer detected by infrared spectroscopy to obtain a blocked isocyanate composition.

[0031] According to the preparation method provided by the present invention, in some examples, a solvent inert to the reaction of NCO groups is added to the reaction system;

[0032] In some examples, the solvent is selected from one or more of 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 of S100 solvent oil, n-butyl acetate and 1-methoxy-2-propyl acetate. The amount of the solvent added here is, for example, based on the complete dissolution of the polyisocyanate and the blocking agent in the reaction system.

[0033] According to the preparation method provided by the present invention, in order to further reduce the chromaticity of the blocked polyisocyanate composition product, an inert gas protection can be used during the reaction process. The inert gas includes but is not limited to one or more of N2, CO2, CO, He and Ar, preferably N2.

[0034] Compared with the prior art, the blocked product prepared from the isophorone diisocyanate composition provided by the present invention has the following beneficial effects:

[0035] 1. Compared with the closed-type products prepared by conventional IPDI, the closed-type products prepared by using the IPDI composition provided by the present invention have a lower unblocking temperature;

[0036] 2. The color increase of the closed product prepared by the IPDI composition provided by the present invention during the unsealing process is lower than that of the closed product prepared by conventional IPDI. DETAILED DESCRIPTION

[0037] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only used to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0038] In the following examples and comparative examples, the sources of the main raw materials are as follows:

[0039] Butanone oxime was purchased from Hubei Xianlin Chemical Industry;

[0040] S100 solvent oil, purchased from ExxonMobil Chemical;

[0041] The color number of the blocked isocyanate composition is tested using a BYK colorimeter.

[0042] The content of methylated isophorone diisocyanate in the isophorone diisocyanate composition can be analyzed by gas chromatography, and the method is: the sample is dissolved in dichloromethane and then analyzed by gas chromatography, detected by a hydrogen ion flame detector (FID), and quantitatively calculated by area normalization method:

[0043] The chromatographic conditions were as follows:

[0044] Carrier gas: purified and dried high-purity nitrogen (purity ≥ 99.999%);

[0045] Combustion gas: hydrogen (purity ≥ 99.999%), flow rate 40mL / min;

[0046] Combustion-supporting gas: purified and dried air, with a flow rate of 400 mL / min;

[0047] Tail gas: nitrogen, flow rate 30mL / min;

[0048] Column flow rate: 1.06 mL / min;

[0049] Split ratio: 30:1;

[0050] Column temperature (programmed temperature rise): 140°C for 0 min, increase the temperature to 220°C at 10°C / min, maintain for 1 min, increase the temperature to 260°C at 5°C / min, maintain for 0 min, increase the temperature to 280°C at 10°C / min, maintain for 1 min;

[0051] Inlet temperature: 270°C;

[0052] Detector temperature: 290°C;

[0053] Injection volume: 0.2 μL.

[0054] The analysis of the color index of the blocked isocyanate composition adopts the method mentioned in the national standard GB / T605-2006.

[0055] The turbidity index of the blocked isocyanate composition is analyzed using the method mentioned in the national standard GB / T605-2006.

[0056] Example 1 Preparation of IPDI compositions with different Me-IPDI contents

[0057] Step A: Preparation of an isophorone diisocyanate composition having a Me-IPDI content of less than 0.002% The synthesis of IPDI is carried out by the method provided in patent CN109761855A in the following steps:

[0058] (1) isophorone is fed to a preheater at a rate of 200 kg / h and preheated to a reaction temperature of 120° C., and then fed to a reactor and an alkaline catalyst sodium methoxide at a molar ratio of 2:1:0.003 under the operating conditions and at an absolute pressure of 1 MPa to obtain isophoronenitrile (3-cyano-3,5,5-trimethylcyclohexanone, abbreviated as IPN) for reaction under the reactor disclosed in Example 1 of CN103301799B. The reaction is carried out for 25 minutes;

[0059] (2) reacting the above-obtained isophorone nitrile, ammonia and hydrogen in the presence of a catalyst, as follows:

[0060] a) reacting the isophoronenitrile obtained in step (1) with ammonia in a tubular reactor, the reaction being carried out at a temperature of 60° C. and an absolute pressure of 15 MPa, wherein the molar ratio of ammonia to isophoronenitrile is 50:1, to obtain 3-cyano-3,5,5-trimethylcyclohexylimine;

[0061] b) in the presence of a hydrogenation catalyst Raney cobalt (the space velocity of the catalyst is 1.5 g 3-cyano-3,5,5-trimethylcyclohexanone / (ml catalyst hour)), hydrogen, NH3 and 3-cyano-3,5,5-trimethylcyclohexyl imine obtained in step a) are mixed and reacted in a 3% KOH ethanol solution, and the reaction is carried out 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;

[0062] In step b), the mass ratio of KOH ethanol solution to the added isophoronenitrile is 1:600, the molar ratio of NH3 to isophoronenitrile is 50:1, and the molar ratio of hydrogen to isophoronenitrile is 80:1;

[0063] c) in the presence of a hydrogenation catalyst Raney cobalt (the space velocity of the catalyst is 1.8 g 3-cyano-3,5,5-trimethylcyclohexanone / (ml catalyst hour)), hydrogen, NH3 and the product containing 3-aminomethyl-3,5,5-trimethylcyclohexylamine and 3-cyano-3,5,5-trimethylcyclohexylamine obtained in step b) are mixed and reacted in a 3% acetic acid-ethanol solution, and the reaction is carried out under a temperature of 120° C. and an absolute pressure of 18 MPa to convert 3-cyano-3,5,5-trimethylcyclohexylamine into 3-aminomethyl-3,5,5-trimethylcyclohexylamine.

[0064] 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 to the IPN obtained in step 1) is 30:1, and the molar ratio of ammonia to the IPN obtained in step a) is 50:1; the chlorine content of the catalyst Raney cobalt used in each step of the above step (2) is 0.0001%;

[0065] (3) The obtained IPDA was gasified and heated to 355° C. using the heater mentioned in Example 1 of Chinese Patent CN105214568A. Under the protection of nitrogen, the IPDA and the gaseous phosgene heated to 355° C. were continuously added to the reactor through respective feed pipes for reaction. The reaction pressure was 0.05 MPa absolute pressure and the temperature was 360° C. The feed amount of IPDA was 800 kg / h and the feed amount of phosgene was 3000 kg / h. The mixed gas after the reaction was subjected to gas purification with o-dichlorobenzene solution. The jet absorption device is rapidly cooled to 100°C to obtain a photochemical liquid containing the product IPDI; excess phosgene is removed at 180°C and an absolute pressure of 0.1 MPa to obtain a crude IPDI product without phosgene; the crude product is then distilled through a distillation tower to obtain an IPDI product at 0.5 KPa and a distillation range of 150-160°C, with a yield of 95% and a purity of 99.85%, wherein the content of Me-IPDI (the sum of the contents of Formulas I, II and III, the same below) is 0.0003% (sample 1).

[0066] Step B: Preparation of an isophorone diisocyanate (IPDI) composition having a Me-IPDI content greater than 0.200%

[0067] The difference from step A is that the chlorine content of the catalyst Raney cobalt used in each step of step (2) is 0.025%, and the solvent used in each step is methanol; the content of Me-IPDI in the obtained IPDI is 0.32% (sample 2).

[0068] Step C: Preparation of IPDI compositions with different Me-IPDI contents

[0069] The obtained samples 1 and 2 were blended in a certain ratio to obtain IPDI compositions with different Me-IPDI contents, which were named as blended samples 1 to 14, wherein the Me-IPDI contents of blended samples 2 to 13 met the requirements of the IPDI compositions of the present invention. The Me-IPDI contents in the IPDI compositions after blending are shown in Table 1 below:

[0070] Table 1 IPDI composition samples and Me-IPDI content

[0071]

[0072]

[0073] Example 2

[0074] 220 kg of the isophorone diisocyanate composition blended sample 2-13 obtained in Example 1 and 100 kg of Mobil S100 solvent oil were added to the reactor respectively, and 175 kg of butanone oxime was added thereto after stirring evenly. The reaction temperature was controlled to 60-70 ° C. and the reaction was stirred until the NCO characteristic absorption peak could not be detected by infrared spectrum. The reaction process was carried out under nitrogen protection, and finally 12 batches of blocked isophorone diisocyanate composition products were obtained, and color number testing was performed.

[0075] 600 g of each of the 12 batches of blocked isocyanate composition products were taken and placed in a 1L three-necked flask, and unsealed by heating in an oil bath at 120°C under nitrogen protection. Through infrared monitoring, it was found that after 2 hours, the NCO characteristic absorption in all samples no longer increased, and all samples were unsealed, and the unsealed samples were subjected to color number testing.

[0076] Comparative Example 1

[0077] 220 kg of the isophorone diisocyanate composition sample 1 and the blended sample 1 obtained in Example 1 and 100 kg of Mobil S100 solvent oil were added to the reactor respectively, and 175 kg of butanone oxime was added thereto after stirring evenly. The reaction temperature was controlled to 60-70 ° C. and the reaction was stirred until the NCO characteristic absorption peak was no longer detected by infrared spectrum. The reaction process was carried out under nitrogen protection, and finally 2 batches of blocked isophorone diisocyanate composition products were obtained, and color number testing was performed.

[0078] 600 g of each of the two batches of blocked isocyanate composition products were put into a 1 L three-necked flask, and unsealed by heating in an oil bath at 120° C. under nitrogen protection. Through infrared monitoring, it was found that after 2 hours, the NCO characteristic absorption in all samples no longer increased, and all samples were unsealed. The unsealed samples were then subjected to color number testing.

[0079] Comparative Example 2

[0080] 220 kg of the isophorone diisocyanate composition sample 2 and the blended sample 14 obtained in Example 1 and 100 kg of Mobil S100 solvent oil were added to the reactor respectively, and 175 kg of butanone oxime was added thereto after stirring evenly. The reaction temperature was controlled to 60-70 ° C. and the reaction was stirred until the NCO characteristic absorption peak could not be detected by infrared spectrum. The reaction process was carried out under nitrogen protection, and finally 2 batches of blocked isophorone diisocyanate composition products were obtained, and color number testing was performed.

[0081] 600 g of each of the two batches of blocked isocyanate composition products obtained by Sample 2 and Blended Sample 14 were put into a 1L three-necked flask, and unsealed by heating in an oil bath at 120°C under nitrogen protection. It was found through infrared monitoring that after 2 hours, the NCO characteristic absorption in all samples continued to increase, and the samples were not yet unsealed. It was found through infrared monitoring that after 4 hours, the NCO characteristic absorption in all samples no longer increased, and all samples were unsealed, and the unsealed samples were subjected to color number testing.

[0082] The color changes of 12 batches of samples in Example 2 and 4 samples in Comparative Examples 1 and 2 during the unsealing process are shown in Table 2:

[0083] Table 2

[0084]

[0085]

[0086] The result data in Table 2 show that the color number increase of the 12 batches of blocked isophorone diisocyanate prepared in Example 2 during the unblocking process is significantly lower than that of the 4 batches of the comparative example, indicating that the blocked product prepared using the isophorone diisocyanate composition provided by the present invention has a significant advantage in stability during the unblocking process over other products.

[0087] The present invention illustrates the detailed method of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned detailed method, that is, it does not mean that the present invention must rely on the above-mentioned detailed method to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of various raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. An isophorone diisocyanate composition, characterized in that: The content of Me-IPDI in the isophorone diisocyanate composition is 0.002wt%-0.200wt%; The general structural formula of the Me-IPDI is: Among them, at least one of R1, R2, R3, R4, R5 and R6 is CH3, and the rest are H.

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

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

4. The isophorone diisocyanate composition according to claim 1, characterized in that: At least one of R1, R3 and R5 has a structure of CH3.

5. The isophorone diisocyanate composition according to any one of claims 1 to 4, characterized in that: The structure of the Me-IPDI is one or more of the following structures:

6. A method for preparing storage-stable blocked isophorone diisocyanate, which is obtained by contacting and reacting the isophorone diisocyanate composition according to any one of claims 1 to 5 with a blocking agent.

7. The preparation method according to claim 6, characterized in that: The blocking agent is a mixture of one or more compounds selected from oxime compounds, alcohol compounds, lactam compounds, pyrazole compounds and β-dicarbonyl compounds.

8. The preparation method according to claim 7, characterized in that: The oxime compound is selected from one or more of butanone oxime, acetone oxime, formaldehyde oxime, acetaldehyde oxime and cyclohexanone oxime.

9. The preparation method according to any one of claims 6 to 8, characterized in that: The ratio of the amount of NCO to the amount of blocking agent in the IPDI composition is 0.9-1:

1.

10. The preparation method according to any one of claims 6 to 8, characterized in that: The reaction temperature is 30-120°C.

11. The preparation method according to any one of claims 6 to 8, characterized in that: The reaction is carried out without solvent or in the presence of solvent.

12. The preparation method according to claim 11, characterized in that: The solvent is selected from one or more of 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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