A blocked isocyanate curing agent, its preparation method and application

Abstract

The present invention provides a blocked isocyanate curing agent, a preparation method thereof and an application. The raw materials for preparing the blocked isocyanate curing agent include polyisocyanate, a modifier and a blocking agent; the modifier includes castor oil-modified polyol. In the present invention, the molecular structure of the blocked isocyanate curing agent contains a castor oil structural unit, so that the blocked isocyanate curing agent has both high hydrophobicity and good toughness, and has good stability and is not prone to gelation; the material cured by using the blocked isocyanate curing agent also has high hydrophobicity and good toughness.

Description

Technical Field

[0001] The present invention belongs to the technical field of curing agents for perovskite materials, and particularly relates to a blocked isocyanate curing agent, a preparation method thereof, and an application thereof. Background Art

[0002] A blocked isocyanate curing agent is prepared by pre-reacting a compound containing active hydrogen with an isocyanate to protect the isocyanate group so that it does not react with a compound containing an active group at room temperature. Since the chemical bond formed between the isocyanate group and the active hydrogen is weak, when the temperature rises to the deblocking temperature, the isocyanate group can be released to continue reacting with a compound containing an active group, thereby obtaining a high-performance material. Moreover, the blocked isocyanate is environmentally friendly, safe, convenient for transportation and storage, and has high production efficiency, and is widely used in fields such as automobiles, electronic appliances, solar cells, and optical devices.

[0003] However, at present, most blocked isocyanate curing agents are directly blocked with blocking agents, and have poor hydrophobicity and flexibility, which in turn leads to poor hydrophobicity and flexibility of the cured material; especially for the blocking modification of isocyanate trimers, gelation is extremely likely to occur and the stability is poor; this limits the application of blocked isocyanate curing agents, especially the curing agents for perovskite metallization materials, which have higher requirements for their hydrophobicity and flexibility.

[0004] Therefore, developing a blocked isocyanate curing agent with both high hydrophobicity and excellent flexibility is an urgent problem to be solved in this field. Summary of the Invention

[0005] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a blocked isocyanate curing agent, a preparation method thereof, and an application thereof. The blocked isocyanate curing agent has both high hydrophobicity and good toughness, and has good stability and is not prone to gelation.

[0006] To achieve this purpose, the present invention adopts the following technical solutions:

[0007] In the first aspect, the present invention provides a blocked isocyanate curing agent, and the preparation raw materials of the blocked isocyanate curing agent include polyisocyanate, a modifier, and a blocking agent; the modifier includes castor oil-modified polyol.

[0008] In the present invention, by modifying the polyisocyanate with a specific type of modifier, a castor oil structural unit is introduced into the molecular structure of the polyisocyanate, so that the curing agent has both high hydrophobicity and good toughness, and the curing agent has good stability; the material cured with the blocked isocyanate curing agent also has high hydrophobicity and good flexibility.

[0009] In the present invention, the castor oil-modified polyol means that the molecular structure of the polyol contains a castor oil acid structural unit, or the raw materials for preparing the polyol include castor oil.

[0010] Preferably, the functionality of the castor oil-modified polyol is ≥2, and can be, for example, 2, 3, 4, 5, 6, etc.

[0011] Preferably, the molar content of hydroxyl groups in the castor oil-modified polyol is 20-30% of the molar content of isocyanate groups in the polyisocyanate, and can be, for example, 20%, 20.5%, 21%, 21.5%, 22%, 22.5%, 23%, 23.5%, 24%, 24.5%, 25%, 25.5%, 26%, 26.5%, 27%, 27.5%, 28%, 28.5%, 29%, 29.5%, 30%, etc.

[0012] Preferably, the number-average molecular weight of the castor oil-modified polyol is 1000-2000, and can be, for example, 1000, 1050, 1100, 1150, 1200, 1250, 1300, 1350, 1400, 1450, 1500, 1550, 1600, 1650, 1700, 1750, 1800, 1850, 1900, 1950, 2000, etc.

[0013] In the present invention, the number-average molecular weight of the castor oil-modified polyol can be measured by a gel permeation chromatograph or obtained from information provided by the manufacturer.

[0014] Preferably, the castor oil-modified polyol includes a first castor oil-modified polyol and a second castor oil-modified polyol; the number-average molecular weight of the first castor oil-modified polyol is less than that of the second castor oil-modified polyol.

[0015] Preferably, the molar ratio of the first castor oil-modified polyol to the second castor oil-modified polyol is 1:(0.1-10), and the specific values in (0.1-10) can be, for example, 0.1, 0.2, 0.4, 0.6, 0.8, 1, 1.2, 1.5, 1.8, 2, 2.2, 2.5, 2.8, 3, 3.2, 3.5, 3.8, 4, 4.2, 4.5, 4.8, 5, 5.2, 5.5, 5.8, 6, 6.2, 6.5, 6.8, 7, 7.2, 7.5, 7.8, 8, 8.2, 8.5, 8.8, 9, 9.2, 9.5, 9.8, 10, etc.

[0016] Preferably, the molar content of active hydrogen in the blocking agent is 70-80% of the molar content of isocyanate groups in the polyisocyanate, and can be, for example, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, etc.

[0017] Preferably, the blocking agent includes at least one of methyl ethyl ketone oxime, diethyl malonate, diisopropylamine or caprolactam.

[0018] Preferably, the functionality of the polyisocyanate is ≥3, for example, it may be 3, 4, 5, 6, etc.

[0019] Preferably, the polyisocyanate includes at least one of hexamethylene diisocyanate (HDI) trimer, hexamethylene diisocyanate biuret, hexamethylene diisocyanate uretdione, pentamethylene pentamethylene diisocyanate (PDI) trimer or isophorone diisocyanate (IPDI) trimer.

[0020] In the present invention, the blocked isocyanate is unblocked at high temperature to obtain a modifier-modified isocyanate and a blocking agent, exposing the isocyanate group, and then the exposed isocyanate group can react with a resin containing an active group, thereby performing curing and cross-linking, which is beneficial to improving the hydrophobicity and flexibility of the resin material; the active group includes a hydroxyl group, an amino group, an epoxy group, etc.

[0021] In a second aspect, the present invention provides a method for preparing the blocked isocyanate curing agent according to the first aspect, the preparation method comprising the following steps:

[0022] The blocked isocyanate curing agent is obtained by reacting the polyisocyanate, the modifier and the blocking agent.

[0023] Preferably, the reaction comprises: (1) mixing a polyisocyanate, a blocking agent and a solvent, and reacting them to obtain a semi-blocked isocyanate curing agent; (2) reacting the semi-blocked isocyanate curing agent obtained in step (1) with a modifier to obtain the blocked isocyanate curing agent.

[0024] Preferably, the reaction temperature in step (1) is 40-60°C, for example, 40°C, 45°C, 50°C, 55°C, 60°C, etc.

[0025] Preferably, the solvent in step (1) comprises at least one of toluene, isopropanol, propylene glycol methyl ether, No. 100 solvent oil, ethyl acetate or butyl acetate.

[0026] In the present invention, the amount of the solvent used is sufficient to completely dissolve the raw materials.

[0027] In the present invention, the reaction in step (1) comprises mixing a polyisocyanate with a solvent, and then adding a blocking agent thereto in batches for reaction. During the reaction, the molar content of isocyanate groups (NCO) in the system is sampled and tested, and the molar content is determined to reach a set value. Exemplarily, the set value is that the molar content of NCO consumed by the added blocking agent accounts for 20% of the total molar amount of NCO, and the set value is 80%.

[0028] The NCO content can be tested by conventional methods in the art. For example, urea can be produced by reacting an isocyanate group with an excess of di-n-butylamine, and then the excess di-n-butylamine can be titrated with hydrochloric acid to quantitatively calculate the content of the isocyanate group.

[0029] Preferably, the reaction temperature in step (2) is 70-80°C, for example, 70°C, 71°C, 72°C, 73°C, 74°C, 75°C, 76°C, 77°C, 78°C, 79°C, 80°C, etc.

[0030] In the present invention, during the reaction process of step (2), the molar content of isocyanate groups (NCO) in the system is sampled and tested. The reaction is complete and the molar content of NCO in the system is close to 0%.

[0031] In a third aspect, the present invention provides a perovskite metallization material, wherein the raw material of the perovskite metallization material includes the blocked isocyanate curing agent described in the first aspect.

[0032] The numerical range described in the present invention not only includes the point values ​​listed above, but also includes any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] The blocked isocyanate curing agent provided by the present invention adopts a specific type of modifier to modify isocyanate and introduces castor oil structural units into the molecular structure of isocyanate, so that the curing agent has both high hydrophobicity and good toughness, and the curing agent has good stability; the material cured by the blocked isocyanate curing agent also has high hydrophobicity and good flexibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is an infrared spectrum of the semi-blocked isocyanate curing agent provided in Example 1 of the present invention.

[0036] Figure 2 This is the infrared spectrum of the blocked isocyanate curing agent provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0037] The technical solution of the present invention will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0038] The materials used in the present invention can all be obtained by purchasing commercially or prepared by conventional methods. Unless otherwise specified, the materials used in the present invention are as follows:

[0039] Castor oil modified polyol 1000: The number average molecular weight is 1000, the functionality is 2, purchased from Vantico, model D1000.

[0040] Castor oil modified polyol 2000: The number average molecular weight is 2000, the functionality is 2, purchased from Vantico, model D2000.

[0041] Castor oil modified polyol 400: The number average molecular weight is 400, the functionality is 2, purchased from Vantico, model D-265.

[0042] Castor oil modified polyol 3000: The number average molecular weight is 3000, the functionality is 2, purchased from Vantico, model D3000.

[0043] Example 1

[0044] This example provides a blocked isocyanate curing agent. The preparation raw materials of the blocked isocyanate curing agent include HDI trimer, modifier and methyl ethyl ketoxime; the molar content of hydroxyl groups in the modifier is 28% of the molar content of isocyanate groups in the HDI trimer, and the modifier includes castor oil modified polyol 1000 and castor oil modified polyol 2000 with a molar ratio of 1:5; the molar content of active hydrogen in the methyl ethyl ketoxime is 72% of the molar content of isocyanate groups in the HDI trimer.

[0045] This example provides a preparation method of a blocked isocyanate curing agent, which specifically includes the following steps:

[0046] (1) Mix and dissolve HDI trimer and toluene (the mass of toluene is one-third of the mass of HDI trimer) in a four-necked flask at 50 °C, and then add 50 mol% of the formulated amount of methyl ethyl ketoxime to react at 50 °C. During the reaction process, sample and test the NCO content until the NCO molar content in the system is 64%; then add the remaining methyl ethyl ketoxime and continue to react at 50 °C until the NCO molar content in the system is 28% to obtain a semi-blocked isocyanate curing agent;

[0047] (2) Add a modifier to the semi-closed isocyanate curing agent obtained in step (1) and react at 75 °C until the NCO in the system has completely reacted to obtain the closed isocyanate curing agent.

[0048] Use a Fourier transform infrared spectrometer to characterize the semi-closed isocyanate curing agent obtained in step (1) and the closed isocyanate curing agent obtained in step (2). The results are as Figure 1 (semi-closed isocyanate curing agent) and Figure 2 (closed isocyanate curing agent) shown; from Figure 1 and Figure 2 it can be seen that Figure 1 there is a characteristic absorption peak of NCO at a wavenumber of about 2260 cm -1 ; Figure 2 the characteristic absorption peak at a wavenumber of about 2260 cm -1 disappears, indicating that the closed isocyanate curing agent has been prepared.

[0049] Example 2

[0050] This example provides a closed isocyanate curing agent. The raw materials for preparing the closed isocyanate curing agent include PDI trimer, a modifier, and diisopropylamine; the molar content of hydroxyl groups in the modifier is 24% of the molar content of isocyanate groups in the PDI trimer. The modifier includes castor oil-modified polyol 1000 and castor oil-modified polyol 2000 with a molar ratio of 1:8; the molar content of active hydrogen in the diisopropylamine is 76% of the molar content of isocyanate groups in the PDI trimer.

[0051] This example provides a method for preparing a closed isocyanate curing agent, which specifically includes the following steps:

[0052] (1) Mix and dissolve PDI trimer and propylene glycol methyl ether (the mass of propylene glycol methyl ether is one-third of the mass of PDI trimer) in a four-necked flask at 50 °C, and then add diisopropylamine to it in four portions and react at 50 °C. During the reaction, sample and test the NCO content until the NCO molar content in the system reaches the required value, that is, until the blocking agent added each time in the system has completely reacted; wherein, the addition amount of the blocking agent each time accounts for 25% of the total molar amount of the blocking agent to obtain a semi-closed isocyanate;

[0053] (2) Add a modifier to the semi-closed isocyanate curing agent obtained in step (1) and react at 78 °C until the NCO in the system has completely reacted to obtain the closed isocyanate curing agent.

[0054] Example 3

[0055] This embodiment provides a blocked isocyanate curing agent. The raw materials for preparing the blocked isocyanate curing agent include HDI biuret, a modifier, and diisopropylamine. The molar content of hydroxyl groups in the modifier is 22% of the molar content of isocyanate groups in HDI biuret. The modifier includes castor oil-modified polyol 1000 and castor oil-modified polyol 2000 with a molar ratio of 1:4. The molar content of active hydrogen in diisopropylamine is 78% of the molar content of isocyanate groups in HDI biuret.

[0056] This embodiment provides a preparation method of a blocked isocyanate curing agent, and the specific steps are the same as those in Embodiment 1.

[0057] Embodiment 4

[0058] This embodiment provides a blocked isocyanate curing agent, and the only difference from Embodiment 1 is that the total molar amount of castor oil polyol 1000 and castor oil polyol 2000 remains unchanged, the molar ratio is 1:1, and other raw materials, dosages, and preparation methods are the same as those in Embodiment 1.

[0059] Embodiment 5

[0060] This embodiment provides a blocked isocyanate curing agent, and the only difference from Embodiment 1 is that the total molar amount of castor oil polyol 1000 and castor oil polyol 2000 remains unchanged, the molar ratio is 1:10, and other raw materials, dosages, and preparation methods are the same as those in Embodiment 1.

[0061] Embodiment 6

[0062] This embodiment provides a blocked isocyanate curing agent, and the only difference from Embodiment 1 is that the total molar amount of castor oil polyol 1000 and castor oil polyol 2000 remains unchanged, there is no castor oil polyol 1000, and other raw materials, dosages, and preparation methods are the same as those in Embodiment 1.

[0063] Embodiment 7

[0064] This embodiment provides a blocked isocyanate curing agent, and the only difference from Embodiment 1 is that the total molar amount of castor oil polyol 1000 and castor oil polyol 2000 remains unchanged, there is no castor oil polyol 2000, and other raw materials, dosages, and preparation methods are the same as those in Embodiment 1.

[0065] Embodiment 8

[0066] This embodiment provides a blocked isocyanate curing agent, which is different from Embodiment 1 only in that the castor oil polyol 1000 is replaced by an equal molar amount of castor oil modified polyol 400, and the castor oil polyol 2000 is replaced by an equal molar amount of castor oil modified polyol 3000, and other raw materials, amounts and preparation methods are the same as those in Embodiment 1.

[0067] Example 9

[0068] This embodiment provides a blocked isocyanate curing agent, which is different from Example 1 only in that the molar content of hydroxyl groups in the modifier is 15% of the molar content of isocyanate groups in the HDI trimer, the molar content of active hydrogen in the methyl ethyl ketone oxime is 85% of the molar content of isocyanate groups in the HDI trimer, and other raw materials, amounts and preparation methods are the same as those in Example 1.

[0069] Example 10

[0070] This embodiment provides a blocked isocyanate curing agent, which is different from Example 1 only in that the molar content of hydroxyl groups in the modifier is 35% of the molar content of isocyanate groups in the HDI trimer, the molar content of active hydrogen in the methyl ethyl ketone oxime is 65% of the molar content of isocyanate groups in the HDI trimer, and other raw materials, amounts and preparation methods are the same as those in Example 1.

[0071] Comparative Example 1

[0072] This comparative example provides a blocked isocyanate curing agent, which differs from Example 1 only in that no castor oil-modified polyol is included in the preparation raw materials, the molar content of active hydrogen in the methyl ethyl ketone oxime is 100% of the molar content of isocyanate groups in the HDI trimer, and other raw materials, amounts and preparation methods are the same as those in Example 1.

[0073] Comparative Example 2

[0074] This comparative example provides a blocked isocyanate curing agent, which differs from Example 1 only in that the modifier is a cashew nut shell liquid bio-based polyol (Cardolite NX9001) with an equal molar amount of hydroxyl groups, and other raw materials, amounts and preparation methods are the same as those in Example 1.

[0075] Performance Testing

[0076] The blocked isocyanate curing agents provided in Examples 1 to 10 and Comparative Examples 1 to 2 were mixed with hydroxypropylene resin (Haoyi New Materials Refober® HYR-2162, with a hydroxyl value of 62 mg KOH / g and a solid content of 52±1%), respectively, wherein the molar ratio of the isocyanate group to the hydroxyl group in the hydroxypropylene resin after the blocked isocyanate curing agent was unblocked was 1.1:1, to prepare a coating; and the coating was subjected to the following performance tests.

[0077] (1) Flexibility test:

[0078] Coat the paint on the commercially available HMC50T5AS release film in Huamei, Jiangyin. The coating thickness is about 100 μm. Bake it at 130 °C for 0.5 h. After cooling, peel to obtain the cured film. Cut it into strips with a length and width of 90×15 mm, and use a universal tensile machine to test the elongation at break (%). Among them, the parameters of the universal tensile machine are: the tensile load is 200 N; the tensile speed is 50 mm / min, and the clamping distance is 50 mm.

[0079] (2) Hydrophobicity test:

[0080] Coat the paint on a smooth glass plate. After baking at 130 °C for 0.5 h, cool it, and test the hydrophobic performance of the obtained film layer; among them, the test method for hydrophobic performance refers to ISO 15989:2004 and is characterized by the contact angle.

[0081] The specific test results are shown in Table 1.

[0082] Table 1

[0083]

[0084] As can be seen from Table 1, for the blocked isocyanate curing agent provided by the present invention, by modifying the isocyanate with a specific type of modifier and introducing a castor oil structural unit into the molecular structure of the isocyanate, the curing agent has both high hydrophobic performance and good toughness, and the curing agent has good stability; the material cured with the blocked isocyanate curing agent also has high hydrophobic performance and good flexibility; the elongation at break of the cured resin is ≥101%, and can even reach more than 120%; the contact angle is ≥90.8°, and can even reach more than 94°.

[0085] As can be seen from Comparative Example 1, the castor oil-modified polyol was not used to modify the isocyanate curing agent, and the toughness and hydrophobic performance of the cured resin were greatly reduced; as can be seen from Comparative Example 2, the castor oil-modified polyol was not used to modify the isocyanate curing agent, and the toughness of the cured resin was significantly worse; and the hydrophobic performance was also worse.

[0086] The above specific embodiments have further detailed the purpose, technical solution and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A closed isocyanate curing agent, characterized in that, The raw materials for preparing the blocked isocyanate curing agent include polyisocyanate, modifier and blocking agent; The modifier includes castor oil-modified polyol; The castor oil-modified polyol includes a first castor oil-modified polyol and a second castor oil-modified polyol; the number-average molecular weight of the first castor oil-modified polyol is less than that of the second castor oil-modified polyol; The molar ratio of the first castor oil-modified polyol to the second castor oil-modified polyol is 1:(0.1~10); The molar content of hydroxyl groups in the castor oil-modified polyol is 20~30% of the molar content of isocyanate groups in the polyisocyanate; The molar content of active hydrogen in the blocking agent is 70~80% of the molar content of isocyanate groups in the polyisocyanate; The number-average molecular weight of the castor oil-modified polyol is 1000~2000.

2. The blocked isocyanate curing agent according to claim 1, characterized in that, The blocking agent includes at least one of methyl ethyl ketoxime, diethyl malonate, diisopropylamine or caprolactam; The functionality of the polyisocyanate ≥ 3; The polyisocyanate includes at least one of hexamethylene diisocyanate trimer, hexamethylene diisocyanate biuret, hexamethylene diisocyanate uretdione, pentamethylene pentadiisocyanate trimer or isophorone diisocyanate trimer.

3. A preparation method of the blocked isocyanate curing agent according to claim 1 or 2, characterized in that, The preparation method includes the following steps: React polyisocyanate, modifier and blocking agent to obtain the blocked isocyanate curing agent.

4. The preparation method according to claim 3, characterized in that, The reaction includes: (1) Mix polyisocyanate, blocking agent and solvent, and react to obtain a semi-blocked isocyanate curing agent; (2) React the semi-blocked isocyanate curing agent obtained in step (1) with the modifier to obtain the blocked isocyanate curing agent.

5. The preparation method according to claim 4, characterized in that The reaction temperature in step (1) is 40~60°C; The solvent in step (1) includes at least one of toluene, isopropanol, propylene glycol methyl ether, solvent naphtha No. 100, ethyl acetate or butyl acetate; The reaction temperature in step (2) is 70~80°C.

6. A perovskite metallization material, characterized in that, The raw materials of the perovskite metallization material include the blocked isocyanate curing agent described in claim 1 or 2.

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