Blocked isocyanate curing agent as well as preparation method and application thereof

Abstract

The invention provides a blocked isocyanate curing agent as well as a preparation method and application thereof. The blocked isocyanate curing agent is prepared from the following raw materials: polyisocyanate, a modifier and a sealing agent, the modifier comprises castor oil modified polyhydric alcohol. According to the invention, the molecular structure of the blocked isocyanate curing agent contains a castor oil structural unit, so that the blocked isocyanate curing agent has high hydrophobicity and good toughness, is good in stability and is not easy to gel; the material cured by the blocked isocyanate curing agent also has high hydrophobicity and good toughness.

Description

Technical Field

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

[0002] Blocked isocyanate curing agent is a compound containing active hydrogen reacted with isocyanate in advance to protect the isocyanate group so that it does not react with compounds containing active groups at room temperature. Since the chemical bond formed between the isocyanate group and the active hydrogen is weak, when the temperature rises to the unblocking temperature, the isocyanate group can be released and continue to react with the compound containing the active group, thereby obtaining a high-performance material. In addition, blocked isocyanates are environmentally friendly and safe, easy to transport and store, and have high production efficiency. They are widely used in the fields of automobiles, electronic appliances, solar cells, optical devices, etc.

[0003] However, currently most blocked isocyanate curing agents are directly blocked with blocking agents, which have poor hydrophobicity and flexibility, resulting in poor hydrophobicity and flexibility of the cured material. In particular, the blocked modification of isocyanate trimers is prone to gelation and has poor stability. This limits the application of blocked isocyanate curing agents, especially those used for perovskite metallization materials, which require higher 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 the art. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention aims to provide a blocked isocyanate curing agent and a preparation method and application thereof. The blocked isocyanate curing agent has high hydrophobicity and good toughness, good stability and is not prone to gelation.

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

[0007] In a first aspect, the present invention provides a blocked isocyanate curing agent, wherein 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.

[0008] In the present invention, polyisocyanate is modified by using a specific type of modifier and castor oil structural units are introduced into the molecular structure of polyisocyanate, 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.

[0009] In the present invention, the castor oil-modified polyol refers to a polyol having a ricinoleic acid structural unit in its molecular structure, or a polyol prepared by using castor oil as its raw material.

[0010] Preferably, the functionality of the castor oil-modified polyol is ≥2, for example, it may be 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, 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, 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 obtained by gel permeation chromatography or from information provided by the manufacturer.

[0014] Preferably, the castor oil-modified polyol comprises 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 smaller than the number average molecular weight 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), wherein the specific value 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, for example, it may be 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 is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0038] The materials used in the present invention can be purchased from the market or prepared by conventional methods. Unless otherwise specified, the materials used in the present invention are as follows:

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

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

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

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

[0043] Example 1

[0044] The present embodiment provides a blocked isocyanate curing agent, wherein the raw materials for preparing the blocked isocyanate curing agent include HDI trimer, a modifier and methyl ethyl ketone oxime; 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 in a molar ratio of 1:5; the molar content of active hydrogen in the methyl ethyl ketone oxime is 72% of the molar content of isocyanate groups in the HDI trimer.

[0045] This embodiment provides a method for preparing a blocked isocyanate curing agent, which specifically comprises the following steps:

[0046] (1) HDI trimer and toluene (the mass of toluene is one third of the mass of HDI trimer) are mixed and dissolved in a four-necked bottle at 50°C, and then 50 mol% of methyl ethyl ketone oxime is added thereto to react at 50°C. During the reaction, samples are taken to test the NCO content until the NCO molar content in the system is 64%; then the remaining methyl ethyl ketone oxime is added thereto, and the reaction is continued at 50°C until the NCO molar content in the system is 28%, thereby obtaining a semi-blocked isocyanate curing agent;

[0047] (2) Adding a modifier to the semi-blocked isocyanate curing agent obtained in step (1), reacting at 75° C. until the NCO in the system is completely reacted, thereby obtaining the blocked isocyanate curing agent.

[0048] The semi-blocked isocyanate curing agent obtained in step (1) and the blocked isocyanate curing agent obtained in step (2) were characterized by Fourier transform infrared spectroscopy. Figure 1 (semi-blocked isocyanate curing agent) and Figure 2 (blocked isocyanate curing agent); Figure 1 and Figure 2 It can be seen that Figure 1 The medium wave number is 2260cm -1 There are characteristic absorption peaks of NCO on the left and right; Figure 2 The medium wave number is 2260cm -1 The characteristic absorption peaks on the left and right disappeared, indicating that a blocked isocyanate curing agent was prepared.

[0049] Example 2

[0050] The present embodiment provides a blocked isocyanate curing agent, wherein the raw materials for preparing the blocked 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, and the modifier includes castor oil modified polyol 1000 and castor oil modified polyol 2000 in 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 embodiment provides a method for preparing a blocked isocyanate curing agent, which specifically comprises the following steps:

[0052] (1) PDI trimer and propylene glycol methyl ether (the mass of propylene glycol methyl ether is one third of the mass of PDI trimer) are mixed and dissolved in a four-necked bottle at 50°C, and then diisopropylamine is added thereto four times, and the reaction is carried out at 50°C. During the reaction, samples are taken to test the NCO content until the NCO molar content in the system reaches the required value, that is, until the blocking agent added to the system each time reacts completely; wherein the amount of blocking agent added each time accounts for 25% of the total molar amount of the blocking agent, and a semi-blocked isocyanate is obtained;

[0053] (2) Adding a modifier to the semi-blocked isocyanate curing agent obtained in step (1), reacting at 78° C. until the NCO in the system is completely reacted, thereby obtaining the blocked isocyanate curing agent.

[0054] Example 3

[0055] The present embodiment provides a blocked isocyanate curing agent, wherein 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 the HDI biuret, and the modifier includes castor oil-modified polyol 1000 and castor oil-modified polyol 2000 in a molar ratio of 1:4; the molar content of active hydrogen in the diisopropylamine is 78% of the molar content of isocyanate groups in the HDI biuret.

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

[0057] Example 4

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

[0059] Example 5

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

[0061] Example 6

[0062] This embodiment provides a blocked isocyanate curing agent, which is different from Embodiment 1 only in that the total molar amount of the castor oil polyol 1000 and the castor oil polyol 2000 remains unchanged, castor oil polyol 1000 is omitted, and other raw materials, amounts and preparation methods are the same as those in Embodiment 1.

[0063] Example 7

[0064] This embodiment provides a blocked isocyanate curing agent, which is different from Embodiment 1 only in that the total molar amount of the castor oil polyol 1000 and the castor oil polyol 2000 remains unchanged, castor oil polyol 2000 is omitted, and other raw materials, amounts and preparation methods are the same as those in Embodiment 1.

[0065] Example 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] The coating was coated on the commercially available HMC50T5AS release film of Jiangyin Huamei with a coating thickness of about 100 μm. The film was baked at 130°C for 0.5 h. After cooling, the cured film was peeled off and cut into strips with a length and width of 90×15 mm. The elongation at break (%) was tested using a universal stretching machine. The parameters of the universal stretching machine were as follows: tensile load of 200 N, tensile speed of 50 mm / min, and clamping distance of 50 mm.

[0079] (2) Hydrophobicity test:

[0080] The coating was applied on a smooth glass plate, baked at 130°C for 0.5h, cooled, and the hydrophobicity of the obtained film layer was tested; wherein the test method for the hydrophobicity was based on ISO 15989:2004 and the contact angle was used for characterization.

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

[0082] Table 1

[0083]

[0084] As can be seen from Table 1, the blocked isocyanate curing agent provided by the present invention, by using a specific type of modifier to modify isocyanate, 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; 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] It can be seen from Comparative Example 1 that the isocyanate curing agent is not modified by castor oil-modified polyol, and the toughness and hydrophobicity of the cured resin are greatly reduced; it can be seen from Comparative Example 2 that the isocyanate curing agent is not modified by castor oil-modified polyol, and the toughness of the cured resin is significantly deteriorated; and the hydrophobicity is also deteriorated.

[0086] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A blocked isocyanate curing agent, characterized in that: 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; The castor oil-modified polyol comprises 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 the number average molecular weight 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).

2. The blocked isocyanate curing agent according to claim 1, characterized in that The functionality of the castor oil modified polyol is ≥2; 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.

3. The blocked isocyanate curing agent according to claim 1, characterized in that: The number average molecular weight of the castor oil modified polyol is 1000-2000.

4. The blocked isocyanate curing agent according to claim 1, characterized in that: The molar content of active hydrogen in the blocking agent is 70-80% of the molar content of isocyanate groups in the polyisocyanate; The blocking agent includes at least one of methyl ethyl ketone oxime, diethyl malonate, diisopropylamine or caprolactam; The functionality of the polyisocyanate is ≥3; The polyisocyanate includes at least one of hexamethylene diisocyanate trimer, hexamethylene diisocyanate biuret, hexamethylene diisocyanate uretdione, pentamethylene pentamethylene diisocyanate trimer or isophorone diisocyanate trimer.

5. A method for preparing a blocked isocyanate curing agent according to any one of claims 1 to 4, characterized in that: The preparation method comprises the following steps: The blocked isocyanate curing agent is obtained by reacting polyisocyanate, a modifier and a blocking agent.

6. The preparation method according to claim 5, characterized in that: The reaction includes: (1) Mixing polyisocyanate, blocking agent and 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.

7. The preparation method according to claim 6, characterized in that: The reaction temperature in step (1) is 40-60°C; 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; The reaction temperature in step (2) is 70-80°C.

8. A perovskite metallization material, characterized in that: The raw material of the perovskite metallization material includes the blocked isocyanate curing agent according to any one of claims 1 to 4.

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