Preparation method of high-viscosity polyurethane acrylate resin

Abstract

The invention relates to a preparation method of high-viscosity polyurethane acrylate resin, which comprises the following steps: mixing 100 parts by mole of polyhydric alcohol and a catalyst under nitrogen protection and mechanical stirring, controlling the temperature to be 50 + / -5 DEG C by using an oil bath pan, dropwise adding 100-200 parts by mole of isocyanate, then controlling the temperature to be 50-60 DEG C, and reacting for 1-2 hours; continuously reacting for 2 to 6 hours to obtain a polyurethane prepolymer; raising the temperature of the polyurethane prepolymer to 60-65 DEG C under nitrogen and mechanical stirring, adding a polymerization inhibitor, then dropwise adding acrylate, and continuously reacting for 0.1-4 hours to obtain the polyurethane acrylate resin. The high-viscosity polyurethane acrylate resin provided by the invention is simple in synthesis process and suitable for large-scale production; wherein the acrylate provides excellent weather resistance, and is matched with the friction resistance and high viscosity of the polyurethane to endow a sample with controllable flowability, infiltration uniformity and structural stability, and has wide application in the field of composite materials and outdoor products; and the curing mode is flexible and controllable to meet different process requirements.

Description

Technical Field

[0001] This invention relates to a resin preparation method, specifically to a method for preparing high-viscosity polyurethane acrylate resin by optimizing the design of raw material formulation and reaction process to achieve efficient synthesis. Background Technology

[0002] Polyurethane acrylate resin (PUA) is widely used in coatings, inks, 3D printing materials, adhesives, and many other fields due to its combination of the high abrasion resistance and flexibility of polyurethane and the weather resistance of acrylate. Another significant advantage of PUA is its highly controllable strength and modulus. By adjusting the ratio of polyurethane to acrylate and the crosslinking density, the mechanical properties of PUA can be controlled within a wide range, from soft elastomers to rigid materials. This controllability allows PUA to meet the needs of different application scenarios, greatly expanding its application scope.

[0003] Currently, we have conducted extensive and in-depth research on low-viscosity PUA systems. However, high-viscosity systems are rarely discussed due to their limited applications and complex reaction processes. Traditional methods for preparing high-viscosity polyurethane acrylate resins mainly include step-growth polymerization and solution polymerization. While step-growth polymerization is relatively simple, it is prone to problems such as a wide molecular weight distribution and difficulty in precisely controlling viscosity, leading to unstable performance of the final product and making it difficult to meet the requirements of high-end applications. Solution polymerization can improve the molecular weight distribution and reaction uniformity to some extent, but it requires the use of large amounts of organic solvents, which not only increases production costs but also causes environmental pollution due to the volatilization of organic solvents. Furthermore, there are issues such as residual organic solvents affecting product performance. In the field of composite materials, high-viscosity resins have advantages such as less loss at mold edges or in fibers, slower loss in fiber bundles, low interfacial porosity, greater stability during storage and transportation, and high stability of prepreg resin content. Therefore, developing a solvent-free method for preparing high-viscosity polyurethane acrylate resins that ensures excellent comprehensive performance and is environmentally friendly is of significant practical importance. Summary of the Invention

[0004] To address the aforementioned problems, the main objective of this invention is to provide a method for preparing high-viscosity polyurethane acrylate resins by optimizing the design of raw material formulations and reaction processes to achieve efficient synthesis.

[0005] This invention solves the above-mentioned technical problems through the following technical solution: a method for preparing high-viscosity polyurethane acrylate resin, the method comprising the following steps:

[0006] On a molar basis, 100 parts of polyol and catalyst were mixed under nitrogen protection and mechanical stirring. The temperature was controlled at 50±5℃ using an oil bath. 100-200 parts of isocyanate were added dropwise. The temperature was then controlled between 50-60℃, and the reaction was continued for 2-6 hours to obtain polyurethane prepolymer.

[0007] Under nitrogen and mechanical stirring, the temperature of the above polyurethane prepolymer was raised to 60-65°C, a polymerization inhibitor was added, and then acrylate was added dropwise. The reaction was continued for 0.1-4 hours to obtain polyurethane acrylate resin.

[0008] In a specific embodiment of the present invention, the polyol is any one or a combination of several of the following: 1,4-butanediol, 1,4-cyclohexanediol, trimethylolpropane, polycaprolactone diol, polypropylene glycol, polycarbonate diol, or polytetrahydrofuran ether diol.

[0009] In a specific embodiment of the present invention, the isocyanate is any one or a combination of several of toluene diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate (MDI), dicyclohexylmethane diisocyanate (H12MDI), hexamethylene diisocyanate (HDI), or isophorone diisocyanate (IPDI).

[0010] In a specific embodiment of the present invention, the mass of the catalyst is 0.01-0.1% of the total mass of the reaction system.

[0011] In a specific embodiment of the present invention, the catalyst is any one of dibutyltin dilaurate, an organobismuth catalyst, or a tertiary amine catalyst.

[0012] In a specific embodiment of the present invention, the mass of the polymerization inhibitor is 0.01-0.1% of the total mass of the reaction system.

[0013] In a specific embodiment of the present invention, the mass of the polymerization inhibitor is p-hydroxyanisole.

[0014] In a specific embodiment of the present invention, the acrylate is a hydroxyl-containing acrylate monomer, specifically any one or a combination of several of the following: hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, pentaerythritol triacrylate, trimethylolpropane diacrylate, or trimethylolpropane diallyl ether.

[0015] The positive and progressive effects of this invention are as follows: The high-viscosity polyurethane acrylate resin preparation method provided by this invention has the following advantages: This invention proposes a simple synthesis process for high-viscosity polyurethane acrylate resin, which is suitable for large-scale production; the acrylate provides excellent weather resistance, which, combined with the abrasion resistance of polyurethane, has a wide range of applications in the field of composite materials and outdoor products; and the curing method is flexible and controllable to meet different process requirements. Detailed Implementation

[0016] The preferred embodiments of the present invention are given below to illustrate the technical solution of the present invention in detail.

[0017] This invention discloses a method for preparing high-viscosity polyurethane acrylate resin, characterized in that the method includes the following steps:

[0018] On a molar basis, 100 parts of polyol and catalyst are mixed under nitrogen protection and mechanical stirring. The temperature is controlled at 50±5℃ using an oil bath. 100-200 parts of isocyanate are added dropwise. The temperature is then controlled between 50-60℃, and the reaction is continued for 2-6 hours to obtain a polyurethane prepolymer. Under nitrogen and mechanical stirring, the temperature of the polyurethane prepolymer is raised to 60-65℃, a polymerization inhibitor is added, and then acrylate is added dropwise. The reaction is continued for 0.1-4 hours to obtain a polyurethane acrylate resin.

[0019] The polyol in this invention is any one or a combination of several of the following: 1,4-butanediol, 1,4-cyclohexanediol, trimethylolpropane, polycaprolactone diol, polypropylene glycol, polycarbonate diol, or polytetrahydrofuran ether diol.

[0020] The isocyanate in this invention is any one or a combination of several of toluene diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate (MDI), dicyclohexylmethane diisocyanate (H12MDI), hexamethylene diisocyanate (HDI), or isophorone diisocyanate (IPDI).

[0021] The mass of the catalyst in this invention is 0.01-0.1% of the total mass of the reaction system.

[0022] The catalyst in this invention is any one of dibutyltin dilaurate, organobismuth catalyst, or tertiary amine catalyst.

[0023] The mass of the polymerization inhibitor in this invention is 0.01-0.1% of the total mass of the reaction system.

[0024] The polymerization inhibitor in this invention is p-hydroxyanisole.

[0025] The acrylates in this invention are hydroxyl-containing acrylate monomers, specifically any one or a combination of several of the following: hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, pentaerythritol triacrylate, trimethylolpropane diacrylate, or trimethylolpropane diallyl ether.

[0026] The following are specific implementation examples:

[0027] Example 1

[0028] 57.6 g of 1,4-cyclohexanediethanol and 0.177 g of dibutyltin dilaurate were mixed under nitrogen protection and mechanical stirring. The temperature was controlled at 50 °C using an oil bath. 131 g of dicyclohexylmethane diisocyanate H12MDI was added dropwise while the temperature was controlled between 50-60 °C. The reaction was continued for 6 h to obtain a polyurethane prepolymer.

[0029] Under nitrogen and mechanical stirring, the temperature of the above polyurethane prepolymer was raised to 60°C, 0.066 g of p-hydroxyanisole was added, and after stirring evenly, a mixture of 20.8 g of hydroxyethyl methacrylate and 11.9 g of pentaerythritol triacrylate was added dropwise. The reaction was continued for 3 h to obtain a high-viscosity polyurethane acrylate resin.

[0030] Example 2

[0031] 57.6 g of 1,4-cyclohexanediethanol and 0.161 g of dibutyltin dilaurate were mixed under nitrogen protection and mechanical stirring. The temperature was controlled at 50 °C using an oil bath. 111 g of isophorone diisocyanate IPDI was added dropwise while the temperature was controlled between 50-60 °C. The reaction was continued for 6 h to obtain a polyurethane prepolymer.

[0032] Under nitrogen and mechanical stirring, the temperature of the above polyurethane prepolymer was raised to 60°C, 0.060 g of p-hydroxyanisole was added, and after stirring evenly, a mixture of 20.8 g of hydroxyethyl methacrylate and 11.9 g of pentaerythritol triacrylate was added dropwise. The reaction was continued for 3 h to obtain a high-viscosity polyurethane acrylate resin.

[0033] Example 3

[0034] Under nitrogen protection and mechanical stirring, 36g of 1,4-butanediethanol and 0.160g of dibutyltin dilaurate were mixed. The temperature was controlled at 50℃ using an oil bath. 131g of dicyclohexylmethane diisocyanate H12MDI was added dropwise while the temperature was controlled between 50-60℃. The reaction was continued for 6 hours to obtain a polyurethane prepolymer.

[0035] Under nitrogen and mechanical stirring, the temperature of the above polyurethane prepolymer was raised to 60°C, 0.060 g of p-hydroxyanisole was added, and after stirring evenly, a mixture of 20.8 g of hydroxyethyl methacrylate and 11.9 g of pentaerythritol triacrylate was added dropwise. The reaction was continued for 3 h to obtain a high-viscosity polyurethane acrylate resin.

[0036] Example 4

[0037] Under nitrogen protection and mechanical stirring, 262g of polycaprolactone diol PCL 205U and 0.341g of dibutyltin dilaurate were mixed. The temperature was controlled at 50℃ using an oil bath. 131g of dicyclohexylmethane diisocyanate H12MDI was added dropwise while the temperature was controlled between 50-60℃. The reaction was continued for 6 hours to obtain the polyurethane prepolymer.

[0038] Under nitrogen and mechanical stirring, the temperature of the above polyurethane prepolymer was raised to 60°C, 0.060 g of p-hydroxyanisole was added, and after stirring evenly, a mixture of 20.8 g of hydroxyethyl methacrylate and 11.9 g of pentaerythritol triacrylate was added dropwise. The reaction was continued for 3 h to obtain a high-viscosity polyurethane acrylate resin.

[0039] Example 5

[0040] Under nitrogen protection and mechanical stirring, 100g of polytetrahydrofuran diol PTHF 250 and 0.211g of dibutyltin dilaurate were mixed. The temperature was controlled at 50℃ using an oil bath. 131g of dicyclohexylmethane diisocyanate H12MDI was added dropwise while the temperature was controlled between 50-60℃. The reaction was continued for 6 hours to obtain the polyurethane prepolymer.

[0041] Under nitrogen and mechanical stirring, the temperature of the above polyurethane prepolymer was raised to 60°C, 0.079 g of p-hydroxyanisole was added, and after stirring evenly, a mixture of 20.8 g of hydroxyethyl methacrylate and 11.9 g of pentaerythritol triacrylate was added dropwise. The reaction was continued for 3 hours to obtain a high-viscosity polyurethane acrylate resin.

[0042] Example 6

[0043] Under nitrogen protection and mechanical stirring, 160g of polypropylene glycol and 0.259g of dibutyltin dilaurate were mixed. The temperature was controlled at 50℃ using an oil bath. 131g of dicyclohexylmethane diisocyanate H12MDI was added dropwise while the temperature was controlled between 50-60℃. The reaction was continued for 6 hours to obtain the polyurethane prepolymer.

[0044] Under nitrogen and mechanical stirring, the temperature of the above polyurethane prepolymer was raised to 60°C, 0.097 g of p-hydroxyanisole was added, and after stirring evenly, a mixture of 20.8 g of hydroxyethyl methacrylate and 11.9 g of pentaerythritol triacrylate was added dropwise. The reaction was continued for 3 h to obtain polyurethane acrylate resin, which is a high-viscosity polyurethane acrylate resin.

[0045] Example 7

[0046] 57.6 g of 1,4-cyclohexanediethanol and 0.178 g of dibutyltin dilaurate were mixed under nitrogen protection and mechanical stirring. The temperature was controlled at 50 °C using an oil bath. 131 g of dicyclohexylmethane diisocyanate H12MDI was added dropwise while the temperature was controlled between 50-60 °C. The reaction was continued for 6 h to obtain a polyurethane prepolymer.

[0047] Under nitrogen and mechanical stirring, the temperature of the above polyurethane prepolymer was raised to 60°C, 0.067 g of p-hydroxyanisole was added, and after stirring evenly, a mixture of 13 g of hydroxyethyl methacrylate and 21.4 g of trimethylolpropane diallyl ether was added dropwise. The reaction was continued for 3 h to obtain a high-viscosity polyurethane acrylate resin.

[0048] Example 8

[0049] 57.6 g of 1,4-cyclohexanediethanol and 0.181 g of dibutyltin dilaurate were mixed under nitrogen protection and mechanical stirring. The temperature was controlled at 50 °C using an oil bath. 131 g of dicyclohexylmethane diisocyanate H12MDI was added dropwise while the temperature was controlled between 50-60 °C. The reaction was continued for 6 h to obtain a polyurethane prepolymer.

[0050] Under nitrogen and mechanical stirring, the temperature of the above polyurethane prepolymer was raised to 60°C, 0.068 g of p-hydroxyanisole was added, and after stirring evenly, a mixture of 13 g of hydroxyethyl methacrylate and 24.2 g of trimethylolpropane diacrylate was added dropwise. The reaction was continued for 3 h to obtain a high-viscosity polyurethane acrylate resin.

[0051] Example 9

[0052] Under nitrogen protection and mechanical stirring, 28.8 g of 1,4-cyclohexanediethanol and 0.112 g of dibutyltin dilaurate were mixed. The temperature was controlled at 50 °C using an oil bath. 78.6 g of dicyclohexylmethane diisocyanate H12MDI was added dropwise while the temperature was controlled between 50-60 °C. The reaction was continued for 6 h to obtain a polyurethane prepolymer.

[0053] Under nitrogen and mechanical stirring, the temperature of the above polyurethane prepolymer was raised to 60°C, 0.068 g of p-hydroxyanisole was added, and after stirring evenly, a mixture of 20.8 g of hydroxyethyl methacrylate and 11.93 g of pentaerythritol triacrylate was added dropwise. The reaction was continued for 3 hours to obtain a high-viscosity polyurethane acrylate resin.

[0054] Comparative Example 1

[0055] The preparation method of the modified silica sol in this comparative example differs from that in Example 1 in that the diisocyanate is replaced by aromatic toluene diisocyanate (TDI) instead of aliphatic dicyclohexylmethane diisocyanate (H12MDI). The specific steps are as follows:

[0056] 57.6 g of 1,4-cyclohexanediethanol and 0.142 g of dibutyltin dilaurate were mixed under nitrogen protection and mechanical stirring. The temperature was controlled at 50 °C using an oil bath. 87 g of toluene diisocyanate (TDI) was added dropwise while the temperature was controlled between 50-60 °C. The reaction was continued for 6 h to obtain a polyurethane prepolymer.

[0057] Under nitrogen and mechanical stirring, the temperature of the above polyurethane prepolymer was raised to 60°C, 0.053 g of p-hydroxyanisole was added, and after stirring evenly, a mixture of 20.8 g of hydroxyethyl methacrylate and 11.9 g of pentaerythritol triacrylate was added dropwise. The reaction was continued for 3 h to obtain a high-viscosity polyurethane acrylate resin.

[0058] Comparative Example 2

[0059] The preparation method of the modified silica sol in this comparative example differs from that in Example 5 in that polytetrahydrofuran diol (PTHF 1000) is replaced with polytetrahydrofuran diol (PTHF 1000). The specific steps are as follows:

[0060] Under nitrogen protection and mechanical stirring, 400g of polytetrahydrofuran diol PTHF 1000 and 0.451g of dibutyltin dilaurate were mixed. The temperature was controlled at 50℃ using an oil bath. 131g of dicyclohexylmethane diisocyanate H12MDI was added dropwise while the temperature was controlled between 50-60℃. The reaction was continued for 6 hours to obtain the polyurethane prepolymer.

[0061] Under nitrogen and mechanical stirring, the temperature of the above polyurethane prepolymer was raised to 60°C, 0.169 g of p-hydroxyanisole was added, and after stirring evenly, a mixture of 20.8 g of hydroxyethyl methacrylate and 11.9 g of pentaerythritol triacrylate was added dropwise. The reaction was continued for 3 h to obtain polyurethane acrylate resin and high viscosity polyurethane acrylate resin.

[0062] The viscosity and refractive index of the final collected products after the reaction in the examples and comparative examples are as follows:

[0063] Table 1

[0064] Viscosity (25℃, Pa·s) Refractive index Example 1 65.4 1.48 Example 2 58.7 1.46 Example 3 56.3 1.48 Example 4 8.2 1.47 Example 5 10.2 1.46 Example 6 8.7 1.45 Example 7 37.1 1.47 Example 8 25.6 1.47 Example 9 9.3 1.48 Comparative Example 1 53.2 1.52 Comparative Example 2 3.6 1.47

[0065] The results of the collected products from the examples and comparative examples show that all samples have high viscosity. The refractive index of H12MDI and IPDI is around 1.47. The presence of benzene rings in TDI increases the refractive index of the sample in comparative example 2 to over 1.5.

[0066] Application examples

[0067] The high-viscosity polyurethane acrylate synthesized in some of the examples and comparative examples was used to prepare coatings. The coatings were uniformly coated on fiberglass cloth. Due to the high viscosity of the coatings, air in the coatings and fiberglass was evacuated using a vacuum hot press to prepare prepregs. (The thermal initiator can also be directly cured in this process, with the temperature set at 160°C, the pressure at 2 MPa, and the duration at 10 minutes.) The photoinitiator was used to cure the prepregs using UV curing (medium-pressure mercury lamp, 80-100 mW / cm2, 30-500 mJ / cm2).

[0068] Application Example 1

[0069] The polyurethane acrylic coating contains the following components in parts by weight.

[0070]

[0071] Application Example 2

[0072] The polyurethane acrylic coating contains the following components in parts by weight.

[0073] Application Example 3

[0074] The polyurethane acrylic coating contains the following components in parts by weight.

[0075] Application Example 4

[0076] The polyurethane acrylic coating contains the following components in parts by weight.

[0077]

[0078] Application Example 5

[0079] The polyurethane acrylic coating contains the following components in parts by weight.

[0080]

[0081] The properties of the composite materials in Application Examples 1-5 above were characterized. Hardness was measured using the pencil method for paints and varnishes according to GB / T 6739-2022. UV aging resistance was tested according to IEC 61215:2005, with a total irradiance of 90 kWh / m² and a required Δb ≤ 3. Tensile strength was tested according to GB / T 13542.2-2009. Light transmittance was tested according to GB / T 2410-2008.

[0082] The results are shown in Table 2 below:

[0083] Table 2

[0084]

[0085] As can be seen from Table 2, Application Example 2 performed best. Application Example 1 may have had poor pencil hardness and mechanical properties due to the addition of UV absorber affecting the curing process. Application Example 3 had excellent performance in all other aspects, but its weather resistance was not satisfactory because toluene diisocyanate contains benzene rings, making it unsuitable for outdoor use.

[0086] The above experimental results show that the novel high-viscosity polyurethane acrylate prepared by this invention has excellent weather resistance, mechanical properties and hardness, and the composite material made by combining it with fiberglass cloth has high light transmittance and also has the advantage of no obvious odor. It has excellent comprehensive performance and has achieved very good technical results.

[0087] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as defined by the appended claims and their equivalents.

Claims

1. A method for preparing a high-viscosity polyurethane acrylate resin, characterized in that, The preparation method of high-viscosity polyurethane acrylate resin includes the following steps: On a molar basis, 100 parts of polyol and catalyst were mixed under nitrogen protection and mechanical stirring. The temperature was controlled at 50±5℃ using an oil bath. 100-200 parts of isocyanate were added dropwise. The temperature was then controlled between 50-60℃ and the reaction was continued for 2-6 hours to obtain polyurethane prepolymer. Under nitrogen and mechanical stirring, the temperature of the above polyurethane prepolymer was raised to 60-65°C, a polymerization inhibitor was added, and then acrylate was added dropwise. The reaction was continued for 0.1-4 hours to obtain polyurethane acrylate resin.

2. The method for preparing high-viscosity polyurethane acrylate resin according to claim 1, characterized in that: The polyol is any one or a combination of several of the following: 1,4-butanediol, 1,4-cyclohexanediol, trimethylolpropane, polycaprolactone diol, polypropylene glycol, polycarbonate diol, or polytetrahydrofuran ether diol.

3. The method for preparing high-viscosity polyurethane acrylate resin according to claim 1, characterized in that: The isocyanate is any one or a combination of several of toluene diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate (MDI), dicyclohexylmethane diisocyanate (H12MDI), hexamethylene diisocyanate (HDI), or isophorone diisocyanate (IPDI).

4. The method for preparing high-viscosity polyurethane acrylate resin according to claim 1, characterized in that: The mass of the catalyst is 0.01-0.1% of the total mass of the reaction system.

5. The method for preparing high-viscosity polyurethane acrylate resin according to claim 1, characterized in that: The catalyst is any one of dibutyltin dilaurate, organobismuth catalyst, or tertiary amine catalyst.

6. The method for preparing high-viscosity polyurethane acrylate resin according to claim 1, characterized in that: The mass of the polymerization inhibitor is 0.01-0.1% of the total mass of the reaction system.

7. The method for preparing high-viscosity polyurethane acrylate resin according to claim 1, characterized in that: The mass of the polymerization inhibitor is p-hydroxyanisole.

8. The method for preparing high-viscosity polyurethane acrylate resin according to claim 1, characterized in that: The acrylate is a hydroxyl-containing acrylate monomer, specifically any one or a combination of several of the following: hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, pentaerythritol triacrylate, trimethylolpropane diacrylate, or trimethylolpropane diallyl ether.

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