Low-RBO epoxy resin and preparation method thereof

Abstract

The invention discloses low-RBO epoxy resin and a preparation method thereof, and relates to the technical field of epoxy resin preparation. The preparation method comprises the following steps: by taking 1, 3, 5-tri (hydroxymethyl) benzene and 1, 1, 1-trifluoro-2, 3-epoxypropane as raw materials, obtaining hyperbranched fluorine-containing polyether polyol under the action of a complex of boron trifluoride diethyl etherate and tetrahydrofuran, mixing the hyperbranched fluorine-containing polyether polyol with excessive isophorone diisocyanate to obtain an isocyanate-terminated fluorine-containing polyurethane prepolymer, and reacting the isocyanate-terminated fluorine-containing polyurethane prepolymer with hydroxyl of glycidol to obtain the hyperbranched fluorine-containing polyurethane prepolymer. The preparation method comprises the following steps: preparing a hyperbranched terminal epoxy group fluorine-containing polyurethane prepolymer, carrying out copolymerization on a small molecular monomer, introducing 1, 3, 5-triaminobenzene to obtain a curing agent with a macromolecular structure, and carrying out crosslinking with epoxy resin under the action of the curing agent to form a network structure, so that the precipitation risk can be reduced compared with surface modification of the epoxy resin.

Description

Technical Field

[0001] This invention relates to the field of epoxy resin preparation technology, specifically a low RBO epoxy resin and its preparation method. Background Technology

[0002] Epoxy resin is a high molecular weight polymer containing two or more epoxy groups. Its backbone structure is an aliphatic, aromatic, or alicyclic organic compound. Through the reaction of epoxy groups with various curing agents, it can form thermosetting products and a three-dimensional network structure. It can be used as an adhesive, insulating material, coating, etc., and is widely used in the electronics, machinery manufacturing, chemical and other industries. It is an indispensable basic material.

[0003] RBO stands for Resin bleeding out, which refers to the exudation or precipitation of resin. Epoxy resin has a high surface energy, resulting in a high surface tension and poor compatibility with low surface energy materials. This makes it prone to phase separation, leading to a decline in product performance.

[0004] Therefore, we propose a low RBO epoxy resin and its preparation method, which reduces the precipitation phenomenon of epoxy resin by preparing an epoxy resin with lower surface energy. Summary of the Invention

[0005] The purpose of this invention is to provide a low RBO epoxy resin and its preparation method to solve the problems raised in the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing a low RBO epoxy resin, comprising the following processes:

[0007] Hyperbranched epoxy-terminated fluorinated polyurethane prepolymer, epoxy resin, curing agent, xylene, and polyoxypropylene glycerol ether are mixed, stirred evenly, and vacuum degassed for 5-15 minutes to obtain low RBO epoxy resin.

[0008] Furthermore, the mass ratio of the hyperbranched terminal epoxy fluorinated polyurethane prepolymer, epoxy resin, curing agent, xylene, and polyoxypropylene glycerol ether is (3-5):10:(0.4-0.6):(3-5):(0.1-0.3).

[0009] Furthermore, the hyperbranched, epoxy-terminated fluorinated polyurethane prepolymer is prepared by the following process:

[0010] Step 1: Mix 1,3,5-tris(hydroxymethyl)benzene, tetrahydrofuran, and boron trifluoride ether, heat to 40-50°C, stir until homogeneous, then add 1,1,1-trifluoro-2,3-epoxypropane solution, stir to react, precipitate, wash, and dry to obtain hyperbranched fluorinated polyether polyol.

[0011] Step 2: Heating the hyperbranched fluorinated polyether polyol to 70-80°C under nitrogen atmosphere protection, then adding isophorone diisocyanate, and reacting at a constant temperature to obtain isocyanate-terminated fluorinated polyurethane prepolymer.

[0012] Step 3: Mix the isocyanate-terminated fluorinated polyurethane prepolymer and glycidol, and heat them under a nitrogen atmosphere to obtain a hyperbranched epoxy-terminated fluorinated polyurethane prepolymer.

[0013] Furthermore, in step 1, the 1,1,1-trifluoro-2,3-epoxypropane solution is obtained by mixing 1,1,1-trifluoro-2,3-epoxypropane with tetrahydrofuran in a ratio of 1g:(4-6)mL.

[0014] Furthermore, in step 1, the ratio of 1,3,5-tris(hydroxymethyl)benzene, tetrahydrofuran, boron trifluoride ether, and 1,1,1-trifluoro-2,3-epoxypropane solution is 1g:(180-200)mL:(1.7-1.9)mL:(38-40)mL.

[0015] Furthermore, in step 1, the process conditions for the stirring reaction are: temperature 20-30℃, time 1.0-1.2h.

[0016] Furthermore, in step 2, the mass ratio of hyperbranched fluorinated polyether polyol to isophorone diisocyanate is 10:(4-6).

[0017] Furthermore, in step 2, the process conditions for the isothermal reaction are: temperature 70–80°C, time 2–3 hours.

[0018] Furthermore, in step 3, the mass ratio of the isocyanate-terminated fluorinated polyurethane prepolymer to glycidol is 1:(2-4).

[0019] Furthermore, in step 3, the process conditions for the heating reaction are: temperature 75-80℃, time 2-4h.

[0020] Furthermore, the curing agent is prepared by the following process:

[0021] S1: Mix dodecyl-11-acrylonitrile, methyl methacrylate, 2-methyl-5,6-dihydroxyhexyl-2-acrylate, isoamyl methacrylate, solvent, and azobisisobutyronitrile, stir evenly, and react with gradient heating. After the reaction is completed, cool down to 73-75℃. After the reaction is completed, extract the solvent to obtain a macromolecular copolymer.

[0022] S2: The macromolecular copolymer is heated to 68-70℃, 1,3,5-triaminobenzene and solvent are added and mixed, and the reaction is carried out with a gradient increase in temperature. After the reaction is completed, the solvent is extracted to obtain the curing agent.

[0023] Furthermore, the solvent is isobutanol.

[0024] Furthermore, in S1, the mass ratio of dodeca-11-acrylonitrile, methyl methacrylate, 2-methyl-5,6-dihydroxyhexyl-2-acrylate, isoamyl methacrylate, solvent, and azobisisobutyronitrile is 10:(1.0~1.2):(2.5~2.7):(4.5~4.7):(16~18):(0.2~0.6).

[0025] Furthermore, in S1, the process conditions for the gradient heating reaction are: first gradient reaction temperature 75-80℃, reaction time 1.5-2.0h;

[0026] The second gradient reaction temperature is 80–85℃, and the reaction time is 1.5–2.0 h.

[0027] The third gradient reaction temperature is 85–90℃, and the reaction time is 1.5–2.0 h.

[0028] Furthermore, in S2, the mass ratio of the macromolecular copolymer, 1,3,5-triaminobenzene, and solvent is 10:(0.5-1.5):(15-20).

[0029] Furthermore, in S2, the process conditions for the gradient heating reaction are: first gradient reaction temperature 75-80℃, reaction time 1.5-2.0h;

[0030] The second gradient reaction temperature is 83–85℃, and the reaction time is 0.5–1.0 h.

[0031] The third gradient reaction temperature is 88–92℃, and the reaction time is 0.5–1.0 h.

[0032] Compared with the prior art, the beneficial effects of the present invention are:

[0033] 1. In this invention, boron trifluoride ether acts as a strong Lewis acid, forming a complex with tetrahydrofuran. This complex protonates the primary hydroxyl group of 1,3,5-tris(hydroxymethyl)benzene to form an oxonium ion, which attacks the epoxy group of 1,1,1-trifluoro-2,3-epoxypropane, opening the ring to form a fluorinated ether segment. The oxonium ion is then regenerated, and the ether oxygen atom in the growing chain attacks the oxonium ion within the same molecule, forming a cyclic structure and generating new fulcrums. This results in a hyperbranched structure, yielding a hyperbranched fluorinated polyether polyol. This polyol is then mixed with excess isophorone diisocyanate to obtain an isocyanate-terminated fluorinated polyurethane prepolymer. Finally, it reacts with the hydroxyl groups of glycidol to obtain a hyperbranched epoxy-terminated fluorinated polyurethane prepolymer.

[0034] Hyperbranched epoxy-terminated fluorinated polyurethane prepolymers also contain benzene rings. Benzene rings are planar rigid structures with large volumes, which can disrupt the arrangement of resin molecular chains, hinder close packing between molecules, inhibit crystallization, and suppress resin precipitation.

[0035] Fluorine is highly polar and can reduce the surface energy of hyperbranched epoxy-terminated fluorinated polyurethane prepolymers, and form a fluorine-rich layer on the epoxy resin surface, reducing resin precipitation.

[0036] 2. In this invention, dodeca-11-acrylonitrile, methyl methacrylate, 2-methyl-5,6-dihydroxyhexyl-2-acrylate, and isoamyl methacrylate are copolymerized under the action of an initiator to form a macromolecular copolymer with hydroxyl side chains, which reacts with the amino group of 1,3,5-triaminobenzene to obtain a curing agent with a macromolecular structure.

[0037] Dodecyl-11-enonitrile has a long-chain alkyl group, which works synergistically with the benzene ring in 1,3,5-triaminobenzene to increase steric hindrance and reduce resin precipitation.

[0038] 3. Hyperbranched epoxy-terminated fluorinated polyurethane prepolymers crosslink with epoxy resin under the action of macromolecular curing agents to form a network structure. Compared with surface modification of epoxy resin, this can reduce the risk of precipitation. Moreover, macromolecular curing agents have larger molecular weights and longer chain segments than small molecule curing agents, and contain multiple crosslinking points, making them less prone to migration. Therefore, they can reduce the risk of epoxy resin precipitation. Detailed Implementation

[0039] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] In the following specific implementation,

[0041] Epoxy resin, grade E44;

[0042] Polyethylene glycol, with an average molecular weight of 2000.

[0043] Example 1: A method for preparing a low RBO epoxy resin, comprising the following processes:

[0044] (1) Preparation of hyperbranched epoxy-terminated fluorinated polyurethane prepolymer:

[0045] 1,1,1-trifluoro-2,3-epoxypropane was mixed with tetrahydrofuran at a ratio of 1 g: 6 mL to obtain a 1,1,1-trifluoro-2,3-epoxypropane solution.

[0046] Step 1: Mix 1,3,5-tris(hydroxymethyl)benzene, tetrahydrofuran, and boron trifluoride diethyl ether, heat to 50°C, stir until homogeneous, then add 1,1,1-trifluoro-2,3-epoxypropane solution, stir to react, precipitate, wash, and dry to obtain hyperbranched fluorinated polyether polyol; Step 2: Heat the hyperbranched fluorinated polyether polyol to 80°C under nitrogen atmosphere, then add isophorone diisocyanate, and react at a constant temperature to obtain isocyanate-terminated fluorinated polyurethane prepolymer; Step 3: Mix the isocyanate-terminated fluorinated polyurethane prepolymer with glycidol, and heat to react under nitrogen atmosphere to obtain hyperbranched epoxy-terminated fluorinated polyurethane prepolymer; In step 1, the ratio of 1,3,5-tris(hydroxymethyl)benzene, tetrahydrofuran, boron trifluoride ether, and 1,1,1-trifluoro-2,3-epoxypropane solution is 1g:200mL:1.9mL:40mL; the reaction conditions in step 1 are: temperature 30℃, time 1.2h; in step 2, the mass ratio of hyperbranched fluorinated polyether polyol to isophorone diisocyanate is 10:6; the isothermal reaction conditions in step 2 are: temperature 80℃, time 3h; in step 3, the mass ratio of isocyanate-terminated fluorinated polyurethane prepolymer to glycidol is 1:4; the heating reaction conditions in step 3 are: temperature 80℃, time 4h.

[0047] (2) Preparation of curing agent:

[0048] S1: Dodecano-11-acrylonitrile, methyl methacrylate, 2-methyl-5,6-dihydroxyhexyl-2-acrylate, isoamyl methacrylate, isobutanol, and azobisisobutyronitrile are mixed and stirred evenly. The mixture is then subjected to a gradient heating reaction. After the reaction is complete, the temperature is lowered to 75°C. Isobutanol is extracted after the reaction to obtain a macromolecular copolymer. S2: The macromolecular copolymer is heated to 70°C, and 1,3,5-triaminobenzene and isobutanol are added and mixed. The mixture is then subjected to a gradient heating reaction. Isobutanol is extracted after the reaction to obtain a curing agent. In S1, dodecano-11-acrylonitrile, methyl methacrylate, 2-methyl-5,6-dihydroxyhexyl-2-acrylate, isoamyl methacrylate, isobutanol, and azobisisobutyronitrile are present. The mass ratio of isobutyronitrile is 10:1.2:2.7:4.7:18:0.6; in S1, the process conditions for the gradient temperature reaction are: first gradient reaction temperature 80℃, reaction time 2.0h; second gradient reaction temperature 85℃, reaction time 2.0h; third gradient reaction temperature 90℃, reaction time 2.0h; in S2, the mass ratio of macromolecular copolymer, 1,3,5-triaminobenzene, and isobutanol is 10:1.5:20; in S2, the process conditions for the gradient temperature reaction are: first gradient reaction temperature 80℃, reaction time 2.0h; second gradient reaction temperature 85℃, reaction time 1.0h; third gradient reaction temperature 92℃, reaction time 1.0h.

[0049] (3) Preparation of low RBO epoxy resin:

[0050] The hyperbranched epoxy-terminated fluorinated polyurethane prepolymer, epoxy resin, curing agent, xylene, and polyoxypropylene glycerol ether were mixed, stirred evenly, and vacuum degassed for 15 min to obtain low RBO epoxy resin. The mass ratio of the hyperbranched epoxy-terminated fluorinated polyurethane prepolymer, epoxy resin, curing agent, xylene, and polyoxypropylene glycerol ether was 5:10:0.6:5:0.3.

[0051] Example 2: A method for preparing a low RBO epoxy resin, comprising the following processes:

[0052] (1) Preparation of hyperbranched epoxy-terminated fluorinated polyurethane prepolymer:

[0053] 1,1,1-trifluoro-2,3-epoxypropane was mixed with tetrahydrofuran at a ratio of 1 g: 5 mL to obtain a 1,1,1-trifluoro-2,3-epoxypropane solution.

[0054] Step 1: 1,3,5-tris(hydroxymethyl)benzene, tetrahydrofuran, and boron trifluoride diethyl ether are mixed, heated to 45°C, stirred until homogeneous, and then 1,1,1-trifluoro-2,3-epoxypropane solution is added. The mixture is stirred to react, and a precipitate is formed. The precipitate is washed and dried to obtain a hyperbranched fluorinated polyether polyol. Step 2: The hyperbranched fluorinated polyether polyol is heated to 75°C under a nitrogen atmosphere, and then isophorone diisocyanate is added. The mixture is reacted at a constant temperature to obtain an isocyanate-terminated fluorinated polyurethane prepolymer. Step 3: The isocyanate-terminated fluorinated polyurethane prepolymer is mixed with glycidol and heated under a nitrogen atmosphere to obtain a hyperbranched epoxy-terminated fluorinated polyurethane prepolymer. In step 1, the ratio of 1,3,5-tris(hydroxymethyl)benzene, tetrahydrofuran, boron trifluoride ether, and 1,1,1-trifluoro-2,3-epoxypropane solution is 1g:190mL:1.8mL:39mL; the reaction conditions in step 1 are: temperature 25℃, time 1.1h; in step 2, the mass ratio of hyperbranched fluorinated polyether polyol to isophorone diisocyanate is 10:5; the reaction conditions in step 2 are: temperature 75℃, time 1.5h; in step 3, the mass ratio of isocyanate-terminated fluorinated polyurethane prepolymer to glycidol is 1:3; the reaction conditions in step 3 are: temperature 78℃, time 3h.

[0055] (2) Preparation of curing agent:

[0056] S1: Dodecano-11-acrylonitrile, methyl methacrylate, 2-methyl-5,6-dihydroxyhexyl-2-acrylate, isoamyl methacrylate, isobutanol, and azobisisobutyronitrile are mixed and stirred evenly. The mixture is then subjected to a gradient heating reaction. After the reaction is complete, the temperature is lowered to 74°C. Isobutanol is extracted after the reaction to obtain the macromolecular copolymer. S2: The macromolecular copolymer is heated to 69°C, and 1,3,5-triaminobenzene and isobutanol are added and mixed. The mixture is then subjected to a gradient heating reaction. Isobutanol is extracted after the reaction to obtain the curing agent. In S1, dodecano-11-acrylonitrile, methyl methacrylate, 2-methyl-5,6-dihydroxyhexyl-2-acrylate, isoamyl methacrylate, isobutanol, and azobisisobutyronitrile are present. The mass ratio of isobutyronitrile is 10:1.1:2.6:4.6:17:0.4; in S1, the gradient temperature reaction conditions are: first gradient reaction temperature 78℃, reaction time 1.8h; second gradient reaction temperature 83℃, reaction time 1.8h; third gradient reaction temperature 88℃, reaction time 1.8h; in S2, the mass ratio of macromolecular copolymer, 1,3,5-triaminobenzene, and isobutanol is 10:1.0:18; in S2, the gradient temperature reaction conditions are: first gradient reaction temperature 78℃, reaction time 1.8h; second gradient reaction temperature 84℃, reaction time 0.8h; third gradient reaction temperature 90℃, reaction time 0.8h.

[0057] (3) Preparation of low RBO epoxy resin:

[0058] Hyperbranched epoxy-terminated fluorinated polyurethane prepolymer, epoxy resin, curing agent, xylene, and polyoxypropylene glycerol ether were mixed, stirred evenly, and vacuum degassed for 10 min to obtain low RBO epoxy resin; the mass ratio of hyperbranched epoxy-terminated fluorinated polyurethane prepolymer, epoxy resin, curing agent, xylene, and polyoxypropylene glycerol ether was 4:10:0.5:4:0.2.

[0059] Example 3: A method for preparing a low RBO epoxy resin, comprising the following processes:

[0060] (1) Preparation of hyperbranched epoxy-terminated fluorinated polyurethane prepolymer:

[0061] 1,1,1-trifluoro-2,3-epoxypropane was mixed with tetrahydrofuran at a ratio of 1 g: 4 mL to obtain a 1,1,1-trifluoro-2,3-epoxypropane solution.

[0062] Step 1: 1,3,5-tris(hydroxymethyl)benzene, tetrahydrofuran, and boron trifluoride diethyl ether are mixed, heated to 40°C, stirred until homogeneous, and then 1,1,1-trifluoro-2,3-epoxypropane solution is added. The mixture is stirred to react, and a precipitate is formed. The precipitate is washed and dried to obtain a hyperbranched fluorinated polyether polyol. Step 2: The hyperbranched fluorinated polyether polyol is heated to 70°C under a nitrogen atmosphere, and then isophorone diisocyanate is added. The mixture is reacted at a constant temperature to obtain an isocyanate-terminated fluorinated polyurethane prepolymer. Step 3: The isocyanate-terminated fluorinated polyurethane prepolymer is mixed with glycidol and heated under a nitrogen atmosphere to obtain a hyperbranched epoxy-terminated fluorinated polyurethane prepolymer. In step 1, the ratio of 1,3,5-tris(hydroxymethyl)benzene, tetrahydrofuran, boron trifluoride ethyl ether, and 1,1,1-trifluoro-2,3-epoxypropane solution is 1g:180mL:1.7mL:38mL; the reaction conditions in step 1 are: temperature 20℃, time 1.0h; in step 2, the mass ratio of hyperbranched fluorinated polyether polyol to isophorone diisocyanate is 10:4; the isothermal reaction conditions in step 2 are: temperature 70℃, time 2h; in step 3, the mass ratio of isocyanate-terminated fluorinated polyurethane prepolymer to glycidol is 1:2; the heating reaction conditions in step 3 are: temperature 75℃, time 2h.

[0063] (2) Preparation of curing agent:

[0064] S1: Dodecano-11-acrylonitrile, methyl methacrylate, 2-methyl-5,6-dihydroxyhexyl-2-acrylate, isoamyl methacrylate, isobutanol, and azobisisobutyronitrile are mixed and stirred evenly. The mixture is then subjected to a gradient heating reaction. After the reaction is complete, the temperature is lowered to 73°C. Isobutanol is extracted after the reaction to obtain a macromolecular copolymer. S2: The macromolecular copolymer is heated to 68°C, and 1,3,5-triaminobenzene and isobutanol are added and mixed. The mixture is then subjected to a gradient heating reaction. Isobutanol is extracted after the reaction to obtain a curing agent. In S1, dodecano-11-acrylonitrile, methyl methacrylate, 2-methyl-5,6-dihydroxyhexyl-2-acrylate, isoamyl methacrylate, isobutanol, and azobisisobutyronitrile are present. The mass ratio of isobutyronitrile is 10:1.0:2.5:4.5:16:0.2; in S1, the process conditions for the gradient temperature reaction are: first gradient reaction temperature 75℃, reaction time 1.5h; second gradient reaction temperature 80℃, reaction time 1.5h; third gradient reaction temperature 85℃, reaction time 1.5h; in S2, the mass ratio of macromolecular copolymer, 1,3,5-triaminobenzene, and isobutanol is 10:0.5:15; in S2, the process conditions for the gradient temperature reaction are: first gradient reaction temperature 75℃, reaction time 1.5h; second gradient reaction temperature 83℃, reaction time 0.5h; third gradient reaction temperature 88℃, reaction time 0.5h.

[0065] (3) Preparation of low RBO epoxy resin:

[0066] The hyperbranched epoxy-terminated fluorinated polyurethane prepolymer, epoxy resin, curing agent, xylene, and polyoxypropylene glycerol ether were mixed, stirred evenly, and vacuum degassed for 5 minutes to obtain low RBO epoxy resin. The mass ratio of the hyperbranched epoxy-terminated fluorinated polyurethane prepolymer, epoxy resin, curing agent, xylene, and polyoxypropylene glycerol ether was 3:10:0.4:3:0.1.

[0067] Comparative Example 1: Compared with Example 1, a method for preparing a low RBO epoxy resin was developed by replacing the hyperbranched fluorinated polyether polyol with polyethylene glycol, comprising the following processes:

[0068] (1) Preparation of epoxy-terminated polyurethane prepolymer:

[0069] Step 1: Polyethylene glycol is heated to 80°C under a nitrogen atmosphere, then isophorone diisocyanate is added, and the reaction is carried out at a constant temperature to obtain an isocyanate-terminated polyurethane prepolymer. Step 2: The isocyanate-terminated polyurethane prepolymer and glycidol are mixed and heated under a nitrogen atmosphere to obtain an epoxy-terminated polyurethane prepolymer. In Step 1, the mass ratio of polyethylene glycol to isophorone diisocyanate is 5:1. The isocyanate reaction conditions in Step 1 are: temperature 80°C, time 3 hours. In Step 2, the mass ratio of isocyanate-terminated polyurethane prepolymer to glycidol is 1:4. The heating reaction conditions in Step 2 are: temperature 80°C, time 4 hours.

[0070] (2) Preparation of curing agent:

[0071] S1: Dodecano-11-acrylonitrile, methyl methacrylate, 2-methyl-5,6-dihydroxyhexyl-2-acrylate, isoamyl methacrylate, isobutanol, and azobisisobutyronitrile are mixed and stirred evenly. The mixture is then subjected to a gradient heating reaction. After the reaction is complete, the temperature is lowered to 75°C. Isobutanol is extracted after the reaction to obtain a macromolecular copolymer. S2: The macromolecular copolymer is heated to 70°C, and 1,3,5-triaminobenzene and isobutanol are added and mixed. The mixture is then subjected to a gradient heating reaction. Isobutanol is extracted after the reaction to obtain a curing agent. In S1, dodecano-11-acrylonitrile, methyl methacrylate, 2-methyl-5,6-dihydroxyhexyl-2-acrylate, isoamyl methacrylate, isobutanol, and azobisisobutyronitrile are present. The mass ratio of isobutyronitrile is 10:1.2:2.7:4.7:18:0.6; in S1, the process conditions for the gradient temperature reaction are: first gradient reaction temperature 80℃, reaction time 2.0h; second gradient reaction temperature 85℃, reaction time 2.0h; third gradient reaction temperature 90℃, reaction time 2.0h; in S2, the mass ratio of macromolecular copolymer, 1,3,5-triaminobenzene, and isobutanol is 10:1.5:20; in S2, the process conditions for the gradient temperature reaction are: first gradient reaction temperature 80℃, reaction time 2.0h; second gradient reaction temperature 85℃, reaction time 1.0h; third gradient reaction temperature 92℃, reaction time 1.0h.

[0072] (3) Preparation of low RBO epoxy resin:

[0073] The epoxy-terminated polyurethane prepolymer, epoxy resin, curing agent, xylene, and polyoxypropylene glycerol ether were mixed in a mass ratio of 5:10:0.6:5:0.3, stirred evenly, and vacuum degassed for 15 minutes to obtain a low RBO epoxy resin.

[0074] Comparative Example 2: Compared with Example 1, the curing agent was replaced with ethylenediamine, and the mass ratio of hyperbranched epoxy-terminated fluorinated polyurethane prepolymer, epoxy resin, ethylenediamine, xylene, and polyoxypropylene glycerol ether was adjusted to 5:10:0.3:5:0.3.

[0075] Comparative Example 3: Compared with Example 1, the hyperbranched fluorinated polyether polyol was replaced with polyethylene glycol, and the curing agent was replaced with ethylenediamine. The preparation of the epoxy-terminated polyurethane prepolymer was the same as in Comparative Example 1. The mass ratio of epoxy-terminated polyurethane prepolymer, epoxy resin, ethylenediamine, xylene, and polyoxypropylene glycerol ether was adjusted to 5:10:0.1:5:0.3.

[0076] Experiment: The low RBO epoxy resins obtained in the examples and comparative examples were tested for their exudation properties. The experiment is as follows:

[0077] Low RBO epoxy resin was dropped onto the light-shielding ink coating, with the droplet diameter controlled at 1 mm. It was left to stand at 25°C for 1 hour, and then placed in an oven and cured at 80°C for 1 hour. The precipitated part was observed using a 100x microscope, and the distance from the edge of the cured low RBO epoxy resin to the edge of the wetted area was measured.

[0078] The table below shows the precipitation distance test results for low RBO epoxy resin;

[0079] Precipitation distance / mm Example 1 0.10 Example 2 0.14 Example 3 0.20 Comparative Example 1 0.31 Comparative Example 2 0.24 Comparative Example 3 0.43

[0080] Based on the table above, the following conclusions can be drawn:

[0081] Compared with Example 1, in Comparative Example 1, the hyperbranched fluorinated polyether polyol was replaced with polyethylene glycol, and the precipitation distance was significantly increased. This is because the hyperbranched fluorinated polyether polyol contains benzene rings and fluorine. The benzene rings hinder the close packing of molecules, inhibit crystallization, and inhibit resin precipitation. Fluorine has strong polarity, which can reduce the surface energy of the hyperbranched epoxy-terminated fluorinated polyurethane prepolymer and form a fluorine-rich layer on the epoxy resin surface, reducing resin precipitation.

[0082] Compared with Example 1, Comparative Example 2 replaced the curing agent with ethylenediamine, and the precipitation distance increased because the curing agent of the present invention introduces long-chain alkyl groups and benzene rings, which synergistically increase steric hindrance and reduce resin precipitation.

[0083] Compared with Example 1, Comparative Example 3 replaced the hyperbranched fluorinated polyether polyol with polyethylene glycol and replaced the curing agent with ethylenediamine, resulting in the largest precipitation distance.

[0084] In summary, the hyperbranched epoxy-terminated fluorinated polyurethane prepolymer and curing agent prepared in this invention can reduce the precipitation of epoxy resin.

[0085] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A method for preparing a low RBO epoxy resin, characterized in that: Including the following processes: Hyperbranched epoxy-terminated fluorinated polyurethane prepolymer, epoxy resin, curing agent, xylene, and polyoxypropylene glycerol ether are mixed, stirred evenly, and vacuum degassed for 5-15 minutes to obtain low RBO epoxy resin.

2. The method for preparing a low RBO epoxy resin according to claim 1, characterized in that: The hyperbranched, epoxy-terminated fluorinated polyurethane prepolymer is prepared by the following process: Step 1: Mix 1,3,5-tris(hydroxymethyl)benzene, tetrahydrofuran, and boron trifluoride ether, heat to 40-50°C, stir until homogeneous, then add 1,1,1-trifluoro-2,3-epoxypropane solution, stir to react, precipitate, wash, and dry to obtain hyperbranched fluorinated polyether polyol. Step 2: Heating the hyperbranched fluorinated polyether polyol to 70-80°C under nitrogen atmosphere protection, then adding isophorone diisocyanate, and reacting at a constant temperature to obtain isocyanate-terminated fluorinated polyurethane prepolymer. Step 3: Mix the isocyanate-terminated fluorinated polyurethane prepolymer and glycidol, and heat them under a nitrogen atmosphere to obtain a hyperbranched epoxy-terminated fluorinated polyurethane prepolymer.

3. The method for preparing a low RBO epoxy resin according to claim 1, characterized in that: The curing agent is prepared by the following process: S1: Mix dodecyl-11-acrylonitrile, methyl methacrylate, 2-methyl-5,6-dihydroxyhexyl-2-acrylate, isoamyl methacrylate, solvent, and azobisisobutyronitrile, stir evenly, and react with gradient heating. After the reaction is completed, cool down to 73-75℃. After the reaction is completed, extract the solvent to obtain a macromolecular copolymer. S2: The macromolecular copolymer is heated to 68-70℃, 1,3,5-triaminobenzene and solvent are added and mixed, and the reaction is carried out with a gradient increase in temperature. After the reaction is completed, the solvent is extracted to obtain the curing agent.

4. The method for preparing a low RBO epoxy resin according to claim 1, characterized in that: The mass ratio of the hyperbranched epoxy-terminated fluorinated polyurethane prepolymer, epoxy resin, curing agent, xylene, and polyoxypropylene glycerol ether is (3-5):10:(0.4-0.6):(3-5):(0.1-0.3).

5. The method for preparing a low RBO epoxy resin according to claim 2, characterized in that: In step 1, the 1,1,1-trifluoro-2,3-epoxypropane solution is obtained by mixing 1,1,1-trifluoro-2,3-epoxypropane with tetrahydrofuran in a ratio of 1g:(4-6)mL; In step 1, the ratio of 1,3,5-tris(hydroxymethyl)benzene, tetrahydrofuran, boron trifluoride ether, and 1,1,1-trifluoro-2,3-epoxypropane solution is 1 g : (180-200) mL : (1.7-1.9) mL : (38-40) mL; In step 2, the mass ratio of hyperbranched fluorinated polyether polyol to isophorone diisocyanate is 10:(4-6); In step 3, the mass ratio of the isocyanate-terminated fluorinated polyurethane prepolymer to glycidol is 1:(2-4).

6. The method for preparing a low RBO epoxy resin according to claim 3, characterized in that: In S1, the mass ratio of dodecyl-11-ene acrylonitrile, methyl methacrylate, 2-methyl-5,6-dihydroxyhexyl-2-acrylate, isoamyl methacrylate, solvent, and azobisisobutyronitrile is 10:(1.0~1.2):(2.5~2.7):(4.5~4.7):(16~18):(0.2~0.6).

7. The method for preparing a low RBO epoxy resin according to claim 3, characterized in that: In S2, the mass ratio of the macromolecular copolymer, 1,3,5-triaminobenzene, and solvent is 10:(0.5~1.5):(15~20).

8. The method for preparing a low RBO epoxy resin according to claim 3, characterized in that: In S1, the process conditions for the gradient temperature rise reaction are: first gradient reaction temperature 75-80℃, reaction time 1.5-2.0h; The second gradient reaction temperature is 80–85℃, and the reaction time is 1.5–2.0 h. The third gradient reaction temperature is 85–90℃, and the reaction time is 1.5–2.0 h.

9. The method for preparing a low RBO epoxy resin according to claim 3, characterized in that: In S2, the process conditions for the gradient temperature rise reaction are: first gradient reaction temperature 75-80℃, reaction time 1.5-2.0h; The second gradient reaction temperature is 83–85℃, and the reaction time is 0.5–1.0 h. The third gradient reaction temperature is 88–92℃, and the reaction time is 0.5–1.0 h.

10. A low RBO epoxy resin, characterized in that: The preparation method according to any one of claims 1 to 9 is obtained.