A low viscosity, high-functionality biuret polyisocyanate composition and a method for making the same
By adding diisocyanate monomers at room temperature and carrying out specific reactions and removal steps, low-viscosity, high-functionality biuret polyisocyanates are prepared, solving the problems of high equipment requirements and difficult control in existing technologies, and realizing low-cost industrial production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- WANHUA CHEMICAL (NINGBO) CO LTD
- Filing Date
- 2022-01-07
- Publication Date
- 2026-07-10
AI Technical Summary
Existing technologies for preparing low-viscosity biuret polyisocyanates require sophisticated equipment and are difficult to control, making it hard to achieve a balance between high functionality and low viscosity, and increasing production costs and environmental pressures.
A low-viscosity, high-functionality biuret polyisocyanate composition was prepared by adding diisocyanate monomers at room temperature and reacting them in the presence of a catalyst at a specific temperature, followed by removal of the monomers by secondary thin-film evaporation.
It achieves viscosity reduction without reducing functionality, simplifies the production process, reduces equipment requirements and costs, and is suitable for industrial production.
Smart Images
Figure BDA0003459466780000051
Abstract
Description
Technical Field
[0001] This invention belongs to the field of isocyanates, specifically relating to a low-viscosity, high-functionality biuret polyisocyanate composition and its preparation method. Background Technology
[0002] Aliphatic or alicyclic biuret polyisocyanates are one of the main raw materials for polyurethane coatings. They are used in combination with alkyd resins, polyester resins, acrylic resins, etc. During use, the isocyanate groups in the biuret polyisocyanates react with the hydroxyl groups in the resin, which plays a particularly important role in the preparation and use of coatings.
[0003] Conventional aliphatic or alicyclic biuret polyisocyanates are mainly prepared by reacting diisocyanates or polyisocyanate monomers with biureting agents (water, amines, alcohols, etc.), and the viscosity of the product is 6000-10000 cP (25℃). During coating preparation, a significant amount of aromatic hydrocarbons and ester solvents need to be added to reduce viscosity and improve workability.
[0004] To reduce viscosity, methods such as reducing conversion rate or controlling composition are usually adopted. The former will reduce the average functionality of the reaction product, requiring a larger amount to be used when preparing coating compositions, increasing costs and being detrimental to the environment; the latter will change the composition of the product, affecting the final product performance.
[0005] US Patent 4837359A discloses a method for preparing low-color-number, low-viscosity biuret polyisocyanate. This method involves reacting diisocyanate with diamine at a temperature above 250°C. The reaction requires rapid mixing of the diisocyanate and diamine within 30 seconds, necessitating a specialized reactor and presenting significant challenges and risks in process control.
[0006] Patent CN101993396A discloses an improved method for preparing polyisocyanates with a biuret structure. This method involves reacting an excess of organic diisocyanate with an organic diamine at high temperature. To ensure rapid reaction and biuret formation, a special mixing chamber / nozzle system is required, making reaction control quite difficult.
[0007] US4388245 discloses a process for preparing low-viscosity biuret polyisocyanate by high-temperature heating. Heating at 100-200°C causes the molecular weight distribution of high-viscosity biuret to shift in a direction that favors the formation of oligomers. After separating the unreacted diisocyanate monomers, a low-viscosity biuret product is obtained.
[0008] As can be seen from the above, the existing conventional preparation processes for low-viscosity biuret polyisocyanates all have high requirements for reaction equipment, are difficult to control, and are not easy to industrialize. Summary of the Invention
[0009] The purpose of this invention is to provide a biuret polyisocyanate composition that has both high functionality and low viscosity.
[0010] To achieve the above objectives, the technical solution adopted by the present invention is as follows:
[0011] A low-viscosity, high-functionality biuret polyisocyanate composition, wherein the polyisocyanate has an average functionality of 3.5-4.5, and the content of isocyanate with a functionality of 2 by weight of total isocyanate is 2-5 wt%. The composition has a viscosity of 1000-6000 cP at 25°C, preferably 1000-4500 cP, and more preferably 1000-3500 cP.
[0012] The inventors made a surprising discovery during their research: adding an additional portion of diisocyanate before monomer removal can reduce viscosity without decreasing the average functionality of the biuret polyisocyanate composition. Further research revealed that adding isocyanate monomers at room temperature does not cause dimerization or alter the polymer composition distribution; therefore, the composition exhibits high functionality, imparting excellent application performance to downstream coating products.
[0013] Another object of the present invention is to provide a method for preparing a biuret polyisocyanate composition.
[0014] A method for preparing the low-viscosity, high-functionality biuret polyisocyanate composition, the method comprising the following steps:
[0015] S1: Diisocyanate A and biuretizing agent react under catalytic conditions to give the intermediate product;
[0016] S2: Cool the intermediate product to a set temperature and then add diisocyanate C to obtain the target reaction solution;
[0017] S3: Remove the diisocyanate monomer from the reaction solution to obtain the final product.
[0018] In this invention, the diisocyanate A in S1 is an aliphatic diisocyanate and / or an alicyclic diisocyanate, preferably one or more of hexamethylene diisocyanate, cyclohexane-1,4-diisocyanate, 1,3-xylidene diisocyanate, di(isocyanate methyl)cyclohexane, trimethyl-1,6-hexamethylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate and isophorone diisocyanate, more preferably hexamethylene diisocyanate and / or isophorone diisocyanate, and even more preferably hexamethylene diisocyanate.
[0019] In this invention, the biuretizing agent in S1 is one or more of water vapor, crystalline hydrate and liquid water, preferably water vapor; preferably, the molar ratio of diisocyanate A and biuretizing agent is (3.5-18):1, more preferably (5-10):1.
[0020] In this invention, the catalyst used in S1 is an acid catalyst, preferably one or more of monoalkyl phosphate, dialkyl phosphate, trialkyl phosphate, monoaryl phosphate, and diaryl phosphate.
[0021] In this invention, the reaction temperature of S1 is 80-250℃, preferably 100-180℃; the reaction time is 0.5-5 hours, preferably 1-3 hours.
[0022] In this invention, the diisocyanate C in S2 is the same as the diisocyanate A in S1.
[0023] In this invention, the mass ratio of diisocyanate C in S2 to diisocyanate A in S1 is (20-1):1, and is optimized to be (10-3):1.
[0024] In this invention, the reaction temperature of S2 is 10-70℃, preferably 20-40℃; the reaction time is 1-5 hours, preferably 2-4 hours.
[0025] In this invention, S3 removes the diisocyanate monomer from the target reaction solution through secondary thin-film evaporation.
[0026] Another object of the present invention is to provide a use of a biuret polyisocyanate composition.
[0027] Use of a biuret polyisocyanate composition, wherein the composition is the above-described low-viscosity, high-functionality biuret polyisocyanate composition, or a low-viscosity, high-functionality biuret polyisocyanate composition prepared by the above method, the composition being used to prepare high-solids-content polyurethane coatings.
[0028] Compared with the prior art, the positive effects of the present invention are as follows:
[0029] (1) The present invention can reduce viscosity without reducing the average functionality of the biuret polyisocyanate composition. The isocyanate monomer added at room temperature will not undergo dimerization and will not change the distribution of polymer components. Therefore, the composition has a high functionality (3.5-4.5), which gives the downstream coating products excellent application performance.
[0030] (2) The method of the present invention does not require additional special equipment, has low production cost, is easy to operate, and can be applied to industrial production. Detailed Implementation
[0031] The present invention will be further illustrated below with specific embodiments. These embodiments are merely illustrative and do not limit the scope of the invention.
[0032] Main raw material information:
[0033] Hexamethylene diisocyanate, Wannate HDI, Wanhua Chemical, 99%;
[0034] Isophorone diisocyanate, Wannate IPDI, Wanhua Chemical, 99%;
[0035] Dicyclohexylmethane diisocyanate, Wannate HMDI, Wanhua Chemical, 99%;
[0036] Trimethyl phosphate, Sigma-Aldrich Chemicals, 99%;
[0037] Dibutyl phosphate, Sigma-Aldrich Chemicals, 99%;
[0038] Viscosity determination: The Brookfield viscometer (model RVDV-II+P) was used for testing at 25°C.
[0039] Color number determination: The color number of biuret polyisocyanate was tested using a BYK LCS IV colorimeter and the Hazen color standard was used.
[0040] NCO content determination: The NCO content was determined using a Metrohm 905 potentiometric titrator.
[0041] Gel chromatography (MZ-Gel SDplus10E3A 5μm column, 35℃, tetrahydrofuran mobile phase, flow rate: 1.0mL / min, analysis time: 40min) was used to quantify the isocyanate feedstock as a means of monitoring the reaction conversion rate (calculated based on the mass of isocyanate).
[0042] The formula for calculating the average functionality f is as follows:
[0043]
[0044] Where f: functionality; M: number-average molecular weight Mn or mass-average molecular weight Mw; A: NCO content of biuret; B: percentage content of the corresponding component.
[0045] Unless otherwise specified, the reaction system is kept under the protection of a dry inert gas (nitrogen) from before the reaction until the addition of the catalyst and throughout the entire reaction process.
[0046] Example 1
[0047] 1) Accurately weigh 2000.0g of hexamethylene diisocyanate using an analytical balance, add it to the reaction vessel at a constant rate using a peristaltic pump, start heating and stirring, and when the temperature reaches 150℃, add 6.0g of accurately weighed trimethyl phosphate using a peristaltic pump, and finally add 38g of water using a steam generator. Control the reaction time to 120min to obtain the reaction intermediate product.
[0048] 2) Accurately weigh 400.0 g of the above reaction intermediate product cooled to 30°C and 1500.0 g of hexamethylene diisocyanate using an analytical balance, add them to a 2L three-necked flask and stir to mix well for 2 hours to obtain the target reaction solution.
[0049] 3) The target reaction solution obtained in step 2 is passed through a two-stage scraped film evaporator to remove the diisocyanate monomer, finally obtaining a biuret polyisocyanate composition. The first-stage separation temperature is 160℃ and the absolute separation pressure is 100Pa; the second-stage separation temperature is 120℃ and the absolute separation pressure is 30Pa.
[0050] The prepared polyisocyanate product was tested and found to have a viscosity of 5120 cP, an NCO% of 22%, an average functionality of 3.7, and a polymer content of 2% with a functionality of 2.
[0051] Example 2
[0052] 1) Accurately weigh 2000.0g of hexamethylene diisocyanate and add it to the reaction vessel at a constant rate using a peristaltic pump. Start heating and stirring. When the temperature reaches 80℃, add 6.0g of accurately weighed trimethyl phosphate using a peristaltic pump. Finally, add 60g of water using a steam generator and control the reaction time to 240min to obtain the reaction intermediate.
[0053] 2) Accurately weigh 100.0 g of the above reaction intermediate product cooled to 28°C and 1500.0 g of hexamethylene diisocyanate using an analytical balance, add them to a 2L three-necked flask and stir to mix well for 2 hours to obtain the target reaction solution.
[0054] 3) The target reaction solution obtained in step 2 is passed through a two-stage scraped film evaporator to remove the diisocyanate monomer, finally obtaining a biuret polyisocyanate composition. The first-stage separation temperature is 160℃ and the absolute separation pressure is 100Pa; the second-stage separation temperature is 120℃ and the absolute separation pressure is 30Pa.
[0055] The prepared polyisocyanate product was tested and found to have a viscosity of 3150 cP, an NCO content of 24.1%, an average functionality of 4.0, and a polymer content of 2% with a functionality of 2.
[0056] Example 3
[0057] 1) Accurately weigh 2000.0g of hexamethylene diisocyanate and add it to the reaction vessel at a constant speed using a peristaltic pump. Start heating and stirring. When the temperature reaches 220℃, add 6.0g of accurately weighed trimethyl phosphate using a peristaltic pump. Finally, add 12g of water using a steam generator and control the reaction time to 50min to obtain the reaction intermediate.
[0058] 2) Accurately weigh 100.0 g of the above reaction intermediate product cooled to 30°C and 1000.0 g of hexamethylene diisocyanate using an analytical balance, add them to a 2L three-necked flask and stir to mix well for 2 hours to obtain the target reaction solution.
[0059] 3) The target reaction solution obtained in step 2 is passed through a two-stage scraped film evaporator to remove the diisocyanate monomer, finally obtaining a biuret polyisocyanate composition. The first-stage separation temperature is 160℃ and the absolute separation pressure is 100Pa; the second-stage separation temperature is 120℃ and the absolute separation pressure is 30Pa.
[0060] The prepared polyisocyanate product was tested and found to have a viscosity of 4220 cP, an NCO content of 23.8%, an average functionality of 3.8, and a polymer content of 3.1% with a functionality of 2.
[0061] Example 4
[0062] 1) Accurately weigh 1000.0g of hexamethylene diisocyanate and add it to the reaction vessel at a constant speed using a peristaltic pump. Start heating and stirring. When the temperature reaches 140℃, add 1.0g of accurately weighed di-n-butyl phosphate using a peristaltic pump. Finally, add 20g of water using a steam generator and control the reaction time to 90min to obtain the reaction intermediate.
[0063] 2) Accurately weigh 200.0 g of the above reaction intermediate product cooled to 25°C and 1500.0 g of hexamethylene diisocyanate using an analytical balance, add them to a 2L three-necked flask and stir to mix well for 3 hours to obtain the target reaction solution.
[0064] 3) The target reaction solution obtained in step 2 is passed through a two-stage scraped film evaporator to remove the diisocyanate monomer, finally obtaining a biuret polyisocyanate composition. The first-stage separation temperature is 130℃ and the absolute separation pressure is 100Pa; the second-stage separation temperature is 120℃ and the absolute separation pressure is 30Pa.
[0065] The prepared polyisocyanate product was tested and found to have a viscosity of 1267 cP, an NCO% content of 22.8%, an average functionality of 3.9, and a polymer content of 4.2% with a functionality of 2.
[0066] Example 5
[0067] 1) Accurately weigh 2000.0g of IPDI and add it to the reaction vessel at a constant speed using a peristaltic pump. Start heating and stirring. When the temperature reaches 170℃, add 7.0g of accurately weighed di-n-butyl phosphate using a peristaltic pump. Finally, add 42g of water using a steam generator and control the reaction time to 180min to obtain the reaction intermediate.
[0068] 2) Accurately weigh 200.0 g of the above reaction intermediate product cooled to 38°C and 1200.0 g of IPDI using an analytical balance, add them to a 2L three-necked flask, stir and mix for 3 hours to obtain the target reaction solution;
[0069] 3) The target reaction solution obtained in step 2 is passed through a two-stage scraped film evaporator to remove the diisocyanate monomer, finally obtaining a biuret polyisocyanate composition. The first-stage separation temperature is 160℃ and the absolute separation pressure is 100Pa; the second-stage separation temperature is 120℃ and the absolute separation pressure is 30Pa.
[0070] The prepared polyisocyanate product was tested and found to have a viscosity of 5140 cP, an NCO% content of 22%, an average functionality of 4.1, and a polymer content of 3.3% with a functionality of 2.
[0071] Example 6
[0072] 1) Accurately weigh 1200.0g of HMDI and add it to the reaction vessel at a constant speed using a peristaltic pump. Start heating and stirring. When the temperature reaches 150℃, add 3.0g of accurately weighed trimethyl phosphate using a peristaltic pump. Finally, add 20g of water using a steam generator and control the reaction time to 150min to obtain the reaction intermediate.
[0073] 2) Accurately weigh 150.0 g of the above reaction intermediate product cooled to 35°C and 1500.0 g of hexamethylene diisocyanate using an analytical balance, add them to a 3L three-necked flask and stir for 4 hours to obtain the target reaction solution.
[0074] 3) The target reaction solution obtained in step 2 is passed through a two-stage scraped film evaporator to remove the diisocyanate monomer, finally obtaining a biuret polyisocyanate composition. The first-stage separation temperature is 160℃ and the absolute separation pressure is 100Pa; the second-stage separation temperature is 120℃ and the absolute separation pressure is 30Pa.
[0075] The prepared polyisocyanate product was tested and found to have a viscosity of 3275 cP, an NCO% content of 23.9%, an average functionality of 3.5, and a polymer content of 2% with a functionality of 2.
[0076] Comparative Example 1
[0077] Compared with Example 2, the difference is that after obtaining the reaction solution, another part of the diisocyanate monomer was not added after cooling before separation.
[0078] 1) Accurately weigh 2000.0g of hexamethylene diisocyanate using an analytical balance, add it to the reaction vessel at a constant rate using a peristaltic pump, start heating and stirring, and when the temperature reaches 150℃, add 6.0g of accurately weighed trimethyl phosphate using a peristaltic pump, and finally add 60g of water using a steam generator. Control the reaction time to 120min to obtain the reaction solution.
[0079] 2) The reaction solution prepared above is passed through a two-stage scraped film evaporator to remove monomers, thereby obtaining the biuret polyisocyanate. The first-stage separation temperature is 150°C and the absolute separation pressure is 100 Pa; the second-stage separation temperature is 120°C and the absolute separation pressure is 50 Pa.
[0080] The prepared polyisocyanate product was tested and found to have a viscosity of 11,500 cP, an NCO% content of 22.1%, an average functionality of 3.5, and a polymer content of 1.8% with a functionality of 2.
[0081] Comparative Example 2
[0082] Compared with Example 5, the difference is that after obtaining the reaction solution, another part of the diisocyanate monomer was not added after cooling before separation.
[0083] 1) Accurately weigh 2000.0g of IPDI and add it to the reaction vessel at a constant speed using a peristaltic pump. Start heating and stirring. When the temperature reaches 170℃, add 7.0g of accurately weighed di-n-butyl phosphate using a peristaltic pump. Finally, add 42g of water using a steam generator and control the reaction time to 180min to obtain the reaction solution.
[0084] 2) The target reaction solution obtained in step 1 is passed through a two-stage scraped film evaporator to remove the diisocyanate monomer, finally obtaining a biuret polyisocyanate composition. The first-stage separation temperature is 160℃ and the absolute separation pressure is 100Pa; the second-stage separation temperature is 120℃ and the absolute separation pressure is 30Pa.
[0085] The prepared polyisocyanate product was tested and found to have a viscosity of 12120 cP, an NCO content of 22.07%, an average functionality of 3.7, and a polymer content of 2% with a functionality of 2.
[0086] Comparative Example 3
[0087] Compared with Example 6, the difference is that after obtaining the reaction solution, another part of the diisocyanate monomer was not added after cooling before separation.
[0088] 1) Accurately weigh 1200.0g of HMDI and add it to the reaction vessel at a constant speed using a peristaltic pump. Start heating and stirring. When the temperature reaches 150℃, add 3.0g of accurately weighed trimethyl phosphate using a peristaltic pump. Finally, add 20g of water using a steam generator and control the reaction time to 150min to obtain the reaction solution.
[0089] 2) The obtained target reaction solution is passed through a two-stage scraped film evaporator to remove the diisocyanate monomer, finally obtaining a biuret polyisocyanate composition. The first-stage separation temperature is 160℃ and the absolute separation pressure is 100Pa; the second-stage separation temperature is 120℃ and the absolute separation pressure is 30Pa.
[0090] The prepared polyisocyanate product was tested and found to have a viscosity of 12015 cP, an NCO content of 24.68%, an average functionality of 3.2, and a polymer content of 1.9% with a functionality of 2.
[0091] The comparison results of the above embodiments and comparative examples indicate that the solution of the present invention can produce low viscosity biuret polyisocyanates while ensuring high functionality.
Claims
1. A low-viscosity, high-functionality biuret polyisocyanate composition, characterized in that, The average functionality of the polyisocyanate is 3.5-4.5, the content of isocyanate with a functionality of 2 based on the total mass of isocyanate is 2-5 wt%, and the viscosity of the composition at 25°C is 1000-6000 cP. The method for preparing the composition includes the following steps: S1: Diisocyanate and biuretizing agent react under catalytic conditions to give intermediate product; S2: Cool the intermediate product to a set temperature and then add diisocyanate to obtain the target reaction solution; S3: Remove the diisocyanate monomer from the reaction solution to obtain the final product.
2. The composition according to claim 1, characterized in that, The viscosity of the polyisocyanate composition at 25°C is 1000-4500 cP.
3. The composition according to claim 2, characterized in that, The viscosity of the polyisocyanate composition at 25°C is 1000-3500 cP.
4. A method for preparing the low-viscosity, high-functionality biuret polyisocyanate composition according to any one of claims 1-3, characterized in that, The method includes the following steps: S1: Diisocyanate A and biuretizing agent react under catalytic conditions to give the intermediate product; S2: Cool the intermediate product to a set temperature and then add diisocyanate C to obtain the target reaction solution; S3: Remove the diisocyanate monomer from the reaction solution to obtain the final product.
5. The method according to claim 4, characterized in that, S1 The diisocyanate A is an aliphatic diisocyanate and / or an alicyclic diisocyanate; And / or, the biuretizing agent described in S1 is one or more of water vapor, crystalline hydrate and liquid water; And / or, the catalyst used in S1 is an acid catalyst; And / or, the reaction temperature of S1 is 80-250℃; the reaction time is 0.5-5 hours.
6. The method according to claim 5, characterized in that, S1 The diisocyanate A is one or more of hexamethylene diisocyanate, cyclohexane-1,4-diisocyanate, 1,3-xylidene diisocyanate, di(isocyanate methyl)cyclohexane, trimethyl-1,6-hexamethylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate and isophorone diisocyanate; And / or, the biuretizing agent described in S1 is water vapor; The molar ratio of diisocyanate A and biuretizing agent in S1 is (3.5-18):1; And / or, the catalyst used in S1 is one or more of the following: monoalkyl phosphate, dialkyl phosphate, trialkyl phosphate, monoaryl phosphate, and diaryl phosphate; And / or, the reaction temperature of S1 is 100-180℃; the reaction time is 1-3 hours.
7. The method according to claim 6, characterized in that, S1 The diisocyanate A is hexamethylene diisocyanate and / or isophorone diisocyanate; The molar ratio of diisocyanate A and biuretizing agent in S1 is (5-10):
1.
8. The method according to claim 7, characterized in that, The diisocyanate A mentioned in S1 is hexamethylene diisocyanate.
9. The method according to claim 4, characterized in that, The diisocyanate C in S2 is the same as the diisocyanate A in S1; And / or, the mass ratio of diisocyanate C in S2 to diisocyanate A in S1 is (20-1):1; And / or, the S2 reaction temperature is 10-70℃; the reaction time is 1-5 hours.
10. The method according to claim 9, characterized in that, The mass ratio of diisocyanate C in S2 to diisocyanate A in S1 is (10-3):1; And / or, the S2 reaction temperature is 20-40℃; the reaction time is 2-4 hours.
11. The method according to claim 4, characterized in that, The S3 removes the diisocyanate monomer from the target reaction solution through a two-stage thin-film evaporation process.
12. Use of a biuret polyisocyanate composition, wherein the composition is a low-viscosity, high-functionality biuret polyisocyanate composition according to any one of claims 1-3, or a low-viscosity, high-functionality biuret polyisocyanate composition prepared by the method according to any one of claims 4-11, the composition being used to prepare high-solids-content polyurethane coatings.