A high molecular weight polyimide epoxy resin, a method of making and use thereof

Abstract

This invention provides a high molecular weight polyimide epoxy resin, its preparation method, and its applications. The raw materials, by weight, include: 100-300 parts of a multifunctional reactive monomer, 120-500 parts of anhydride, 300-500 parts of solvent A, 380-450 parts of epoxy resin, 70-90 parts of an active monomer, 80-120 parts of solvent B, 2-6 parts of initiator, 100-110 parts of alkanolamine, 120-300 parts of curing agent, and 50-100 parts of neutralizing agent. The prepared resin exhibits excellent physicochemical stability, good temperature resistance, good selectivity, high exchange capacity, resistance to organic pollution, high mechanical strength, and good impermeability. It can be applied to electrophoretic paints, architectural coatings, engineering plastics, and composite materials.

Description

Technical Field

[0001] This invention relates to the field of C09D5 / 44, and more specifically to a high molecular weight polyimide epoxy resin, its preparation method, and its application. Background Technology

[0002] Epoxy resins are widely used in coatings and other fields due to their excellent physical and chemical properties after curing. However, as the defects of conventional spraying continue to emerge, electrophoretic coatings are becoming increasingly popular. Since the advent of cathodic electrophoretic coatings, the excellent corrosion resistance and mechanical properties of the coating film they form, as well as their suitability for automated coating processes, have led to their rapid adoption in industry.

[0003] CN105820742B discloses a method for preparing a high-solids, low-viscosity cathodic electrophoretic coating. The method involves chain extension of epoxy resin, followed by ring-opening with diethanolamine and polyamide, and finally grafting with a semi-closed curing agent to obtain the main resin. Polyether polyol is added, and pigments and fillers with low oil absorption are used to increase the solids content and reduce the viscosity of the color paste, thereby reducing the amount of color paste needed to be replaced in the electrophoretic paint tank and thus reducing usage costs. Furthermore, by improving the synthesis method of the dispersion resin, the molecular weight of the polymer is reduced, thereby improving its viscosity and reducing production difficulty.

[0004] CN111019441B discloses a color paste for cathodic electrophoretic paint and its preparation method. The raw materials include decylphenol-modified epoxy resin, ethylene glycol butyl ether, ethylene glycol, butanol, carbon black, hydroxycellulose, iron oxide, acetic acid, and titanium dioxide. By selecting a specific decylphenol-modified epoxy resin and mixing it with other specific components as the raw material for the color paste, the salt spray resistance and penetration of the cathodic electrophoretic paint prepared from the color paste are effectively improved, thereby increasing the productivity of electrophoretic coating.

[0005] However, most of the existing electrophoretic paints prepared from epoxy resins are low molecular weight resins, which results in poor heat resistance and solvent resistance of the electrophoretic paints. Summary of the Invention

[0006] To address the aforementioned problems, this invention discloses a high molecular weight polyimide epoxy resin, wherein the raw materials for preparation, by weight, include: 100-300 parts of multifunctional reactive monomer, 120-500 parts of acid anhydride, 300-500 parts of solvent A, 380-450 parts of epoxy resin, 70-90 parts of reactive monomer, 80-120 parts of solvent B, 2-6 parts of initiator, 100-110 parts of alkanolamine, 120-300 parts of curing agent, and 50-100 parts of neutralizing agent.

[0007] In one embodiment, the multifunctional reactive monomer is an alcohol-containing and / or amine-containing multifunctional reactive monomer.

[0008] Preferably, the multifunctional reactive monomer is an amine-containing multifunctional reactive monomer.

[0009] Furthermore, the multifunctional reactive monomer is an aromatic diamine, including but not limited to 3,3'-dichloro-4,4'-diaminophenylmethane (MOCA), 3,5-dimethylthiotoluenediamine (DMTDA, E-300), diethyltoluenediamine (DETDA, E-100), 4,4'-methylenebis(3-chloro-2,6-diethylaniline) (MCDEA), 1,3-propanediol bis(4-aminobenzoate) (740M), 4,4'-methylenebis(2-ethyl)aniline (MOEA), 3-chloro-4,4'-diaminodiphenylmethane (ML-400), and bis-sec-butylaminodiphenylmethane (MDBA) and 4,4-diaminodiphenyl ether (ODA).

[0010] More preferably, the multifunctional reactive monomer is 4,4-diaminodiphenyl ether.

[0011] In one embodiment, the acid anhydride is selected from inorganic acid anhydrides and / or organic acid anhydrides.

[0012] Preferably, the acid anhydride is an organic acid anhydride.

[0013] More preferably, the acid anhydride is C3-C. 10 Small molecule anhydrides, preferably maleic anhydrides.

[0014] In one embodiment, solvent A is a polar and / or nonpolar solvent.

[0015] Preferably, solvent A is a mixture of polar and nonpolar solvents in a mass ratio of (2-5):1.

[0016] More preferably, the polar solvent is N-methylpyrrolidone.

[0017] More preferably, the nonpolar solvent is xylene.

[0018] In one embodiment, the epoxy resin is selected from any one of bisphenol A type epoxy resin, bisphenol F type epoxy resin, polyphenol type glycidyl ether epoxy resin, and glycidyl ester type epoxy resin.

[0019] Preferably, the epoxy resin is a bisphenol A type epoxy resin.

[0020] More preferably, the epoxy value of the epoxy resin is >0.4eq / 100g.

[0021] More preferably, the epoxy value of the epoxy resin is >0.45 eq / 100g.

[0022] In one embodiment, the active monomer is an acrylic monomer and / or an acrylate monomer.

[0023] Preferably, the active monomer is an acrylic acid monomer.

[0024] More preferably, the acrylic monomer is methacrylic acid.

[0025] In one embodiment, the solvent B is selected from any one of alcohols, ketones, and esters.

[0026] Preferably, solvent B is a ketone.

[0027] More preferably, solvent B is a polar ketone solvent, and more preferably N-methylpyrrolidone.

[0028] In one embodiment, the initiator is a free radical initiator.

[0029] Preferably, the initiator is an azo initiator.

[0030] More preferably, the initiator is azobisisobutyronitrile.

[0031] In one embodiment, the alkanolamine is selected from one or more of monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, and triisopropanolamine (TIPA).

[0032] Preferably, the alcoholamine is diethanolamine.

[0033] In one embodiment, the neutralizing agent is an organic acid.

[0034] Preferably, the neutralizing agent is acetic acid.

[0035] In one embodiment, the curing agent is selected from one or more of the following: fatty amine curing agents, polyamide curing agents, aromatic amine curing agents, polyether amine curing agents, dicyandiamide curing agents, acid anhydride curing agents, and isocyanate curing agents.

[0036] Preferably, the curing agent is an isocyanate-based curing agent.

[0037] Through extensive research, the inventors discovered that the modified epoxy resin prepared by the above method can achieve an average molecular weight of 5,000-20,000, giving the epoxy resin emulsion excellent solvent resistance and heat resistance. The applicant believes the possible reason is that by reacting multifunctional reactive monomers with organic acid anhydrides and imidizing them, a trimer containing unsaturated double bonds as end groups is obtained. Then, this trimer is reacted with a monomer with an unsaturated double bond at one end and an epoxy group at the other end via an olefin addition reaction, resulting in an epoxy resin with a higher molecular weight. The above process introduces PI groups into epoxy resin, improving the heat resistance, solvent resistance, and insulation properties of the epoxy resin emulsion film. Most importantly, the epoxy resin prepared in this invention incorporates unsaturated double-bond-terminated polyimide, resulting in a higher degree of crosslinking during subsequent curing. Furthermore, when the epoxy resin is a bisphenol A type epoxy resin, it forms a complex air-dropped network structure. As the temperature rises, the average intermolecular distance increases, while the expansion of the network structure reduces the intermolecular distance. The extension and contraction of the network structure can mitigate the effects of temperature, thus exhibiting good resistance to temperature changes.

[0038] Another aspect of the present invention discloses a method for preparing the high molecular weight polyimide epoxy resin, comprising the following steps:

[0039] (1) The multifunctional reactive monomer and acid anhydride are added to a flask equipped with a water separator, and solvent A is added at the same time. After reflux in an oil bath, water and part of the solvent are removed by vacuum filtration to obtain solution I.

[0040] (2) Add epoxy resin and active monomer to a flask, and add solvent B to react and obtain solvent II.

[0041] (3) Take solution I, solution II and initiator, add them to a flask, react at 70-90℃ for 2-4 hours, then add alkanolamine, react at 90-120℃ for 2-4 hours, add curing agent and neutralizing agent to obtain high molecular weight polyimide epoxy resin.

[0042] In one embodiment, step (1) specifically involves adding the multifunctional reactive monomer and acid anhydride to a flask equipped with a water separator, adding solvent A at the same time, stirring evenly, and then refluxing in an oil bath at 140-170℃ for 3-5 hours. The solution is then completely removed by vacuum filtration to obtain solution I.

[0043] In one embodiment, step (2) specifically involves adding epoxy resin and active monomer to a flask, adding solvent B, and reacting at 120-140°C for 5-10 hours to obtain solution II.

[0044] In one embodiment, step (3) specifically involves: taking solution I, solution II, and initiator, adding them to a flask, reacting at 70-90°C for 2-4 hours, adding an alcohol amine, and reacting at 90-120°C for 2-4 hours, adding a curing agent, and neutralizing with a neutralizing agent to obtain a high molecular weight polyimide epoxy resin.

[0045] In one embodiment, the molar ratio of the trimer in solvent I to the epoxy resin in solvent II is (0.5-2):1; preferably 1:1.

[0046] The third aspect of this invention discloses the application of the high molecular weight polyimide epoxy resin, which is used in electrophoretic paints, architectural coatings, engineering plastics and composite materials.

[0047] Beneficial effects

[0048] 1. By reacting multifunctional reactive monomers with organic acid anhydrides and imidizing them, trimers containing unsaturated double bonds as end groups can be obtained.

[0049] 2. Specific epoxy resins react with reactive monomers to obtain monomers with an unsaturated double bond at one end and an epoxy at the other end. Through olefin addition reactions, epoxy resins with higher molecular weights can be obtained.

[0050] 3. Introducing PI groups into epoxy resin improves the heat resistance, solvent resistance, and insulation properties of the epoxy resin emulsion after film formation.

[0051] 4. Unsaturated double-bond-terminated polyimide is introduced, and when the epoxy resin is bisphenol A type epoxy resin, the degree of crosslinking of the system will be higher and the heat resistance will be better during the subsequent curing process, reaching 400℃.

[0052] 5. The prepared resin has excellent physicochemical stability, good temperature resistance, good selectivity, high exchange capacity, resistance to organic pollution, high mechanical strength, and good impermeability. It can be applied to electrophoretic paint, architectural coatings, engineering plastics and composite materials. Attached Figure Description

[0053] Figure 1 Image of the epoxy resin emulsion obtained by stirring the resin prepared in Example 1 with water.

[0054] Figure 2 Figure 1 shows the TGA test results of the electrophoretic coating film in Example 1.

[0055] Figure 3 TGA test results of unmodified ordinary epoxy electrophoretic coating film.

[0056] Figure 4Infrared spectrum of the paint film formed by the modified resin prepared in Example 1. Detailed Implementation

[0057] Example 1

[0058] Example 1 discloses a high molecular weight polyimide epoxy resin. The raw materials for preparation, by weight, are: 200 parts 4,4-diaminodiphenyl ether, 196 parts maleic anhydride, 400 parts solvent A, 392 parts epoxy resin, 86 parts methacrylic acid, 100 parts solvent B, 4 parts azobisisobutyronitrile, 105 parts diethanolamine, 200 parts curing agent, and 70 parts neutralizing agent.

[0059] Solvent A is N-methylpyrrolidone and xylene in a mass ratio of 3:1.

[0060] The epoxy resin is epoxy resin E51.

[0061] The neutralizing agent is acetic acid.

[0062] The curing agent is toluene diisocyanate.

[0063] This embodiment 1 also discloses a method for preparing the high molecular weight polyimide epoxy resin, the steps of which are as follows:

[0064] (1) Add 4,4-diaminodiphenyl ether and maleic anhydride to a flask with a water separator, and add 300 parts of N-methylpyrrolidone and 100 parts of xylene. Stir well and reflux in an oil bath at 160°C for 4 hours. Filter under reduced pressure to completely remove water and xylene from the solution to obtain solution I.

[0065] (2) Add epoxy resin E51 and methacrylic acid to a flask, and add 100 parts of N-methylpyrrolidone. React at 130℃ for 7 hours to obtain solution II.

[0066] (3) Add solution I, solution II and azobisisobutyronitrile to a flask and react at 80°C for 3 hours. Add diethanolamine and react at 105°C for 3 hours. Add curing agent and neutralize with acetic acid to obtain high molecular weight polyimide epoxy resin.

[0067] The molar ratio of the trimer in solvent I to the epoxy resin in solvent II is 1:1.

[0068] Example 2

[0069] Example 2 discloses a high molecular weight polyimide epoxy resin. The raw materials for preparation are, by weight: 200 parts 4,4-diaminodiphenyl ether, 328 parts norbornene adienoic anhydride, 400 parts solvent A, 392 parts epoxy resin, 86 parts methacrylic acid, 100 parts solvent B, 4 parts azobisisobutyronitrile, 105 parts diethanolamine, 200 parts curing agent, and 70 parts neutralizing agent.

[0070] Solvent A is N-methylpyrrolidone and xylene in a mass ratio of 3:1.

[0071] The epoxy resin is epoxy resin E51.

[0072] The neutralizing agent is acetic acid.

[0073] The curing agent is toluene diisocyanate.

[0074] This embodiment 2 also discloses a method for preparing the high molecular weight polyimide epoxy resin, the steps of which are as follows:

[0075] (1) Add 4,4-diaminodiphenyl ether and norborneol ediol to a flask with a water separator, and add 300 parts of N-methylpyrrolidone and 100 parts of xylene. Stir well and reflux in an oil bath at 160°C for 4 hours. Remove water and xylene from the solution by vacuum filtration to obtain solution I.

[0076] (2) Add epoxy resin E51 and methacrylic acid to a flask, and add 100 parts of N-methylpyrrolidone. React at 130℃ for 7 hours to obtain solution II.

[0077] (3) Add solution I, solution II and azobisisobutyronitrile to a flask and react at 80°C for 3 hours. Add diethanolamine and react at 105°C for 3 hours. Add curing agent and neutralize with acetic acid to obtain high molecular weight polyimide epoxy resin.

[0078] The molar ratio of the trimer in solvent I to the epoxy resin in solvent II is 1:1.

[0079] Example 3

[0080] Example 3 discloses a high molecular weight polyimide epoxy resin, the raw materials for which, by mass, are: 178 parts diethyltoluene diamine, 196 parts maleic anhydride, 400 parts solvent A, 392 parts epoxy resin, 86 parts methacrylic acid, 100 parts solvent B, 4 parts azobisisobutyronitrile, 105 parts diethanolamine, 200 parts curing agent, and 70 parts neutralizing agent.

[0081] Solvent A is N-methylpyrrolidone and xylene in a mass ratio of 3:1.

[0082] The epoxy resin is epoxy resin E54.

[0083] The neutralizing agent is acetic acid.

[0084] The curing agent is toluene diisocyanate.

[0085] This embodiment 3 discloses another aspect of the preparation method of the high molecular weight polyimide epoxy resin, the steps of which are as follows:

[0086] (1) Add diethyltoluenediamine and maleic anhydride to a flask with a water separator, and add 300 parts of N-methylpyrrolidone and 100 parts of xylene. Stir well and reflux in an oil bath at 160°C for 4 hours. Remove water and xylene from the solution by vacuum filtration to obtain solution I.

[0087] (2) Add epoxy resin E54 and methacrylic acid to a flask, and add 100 parts of N-methylpyrrolidone. React at 130℃ for 7 hours to obtain solution II.

[0088] (3) Add solution I, solution II and azobisisobutyronitrile to a flask and react at 80°C for 3 hours. Add diethanolamine and react at 105°C for 3 hours. Add curing agent and neutralize with acetic acid to obtain high molecular weight polyimide epoxy resin.

[0089] The molar ratio of the trimer in solvent I to the epoxy resin in solvent II is 1:1.

[0090] Example 4

[0091] The difference between this embodiment and Embodiment 1 is that the molar ratio of the trimer in solvent I to the epoxy resin in solvent II is 2:1.

[0092] Example 5

[0093] The difference between this embodiment and Embodiment 1 is that the molar ratio of the trimer in solvent I to the epoxy resin in solvent II is 3:1.

[0094] Example 6

[0095] The difference between this embodiment and Embodiment 1 is that the epoxy resin is bisphenol F type epoxy resin, purchased from Shenzhen Winova Chemical Materials Co., Ltd., model NPEF-170.

[0096] Performance testing

[0097] 1. Stability test: The resins obtained in Examples 1-6 were placed at 50°C for one week and observed daily. The results are shown in Table 1 below.

[0098] stability Example 1 Stable, no sedimentation Example 2 Stable, no sedimentation Example 3 Stable, no sedimentation Example 4 Unstable, sediment appeared on the third day. Example 5 Unstable, sediment appeared on the first day. Example 6 Stable, no sedimentation

[0099] The resin emulsions prepared in Examples 1-3 and Example 6 were diluted to achieve a solid content of 15 wt%, and electrophoretic film was formed. Infrared spectroscopy was performed on the film from Example 1, and the results are as follows: Figure 4 The electrophoresis voltage was 120V and the film thickness was 25μm. The following tests were performed.

[0100] 2. Electrolyte resistance: After electrolyte titration, bake at 85℃ for 2 hours.

[0101] 3. Dielectric strength: Tested according to GB / T 1408.2.

[0102] 4. Acid and alkali resistance: GB / T9274-1988, acid is 5wt% HCl aqueous solution, alkali is 5wt% NaOH aqueous solution, 2h.

[0103]

[0104]

[0105] 5. Heat resistance: The electrophoretic coating film obtained in Example 1 was subjected to TGA testing, and the results are as follows: Figure 2 The TGA test results for the ordinary epoxy resin electrophoretic coating film without modification are as follows: Figure 3 It is evident that the heat resistance has improved, increasing from 200℃ to over 400℃.

Claims

1. A modified epoxy resin, characterized in that, The raw materials prepared by weight are: 200 parts 4,4-diaminodiphenyl ether, 196 parts maleic anhydride, 400 parts solvent A, 392 parts epoxy resin, 86 parts methacrylic acid, 100 parts solvent B, 4 parts azobisisobutyronitrile, 105 parts diethanolamine, 200 parts curing agent, and 70 parts neutralizing agent. Solvent A is N-methylpyrrolidone and xylene in a mass ratio of 3:1; Solvent B is N-methylpyrrolidone; The epoxy resin is epoxy resin E51; The neutralizing agent is acetic acid; The curing agent is toluene diisocyanate; The preparation method of the modified epoxy resin includes the following steps: (1) Add 4,4-diaminodiphenyl ether and maleic anhydride to a flask equipped with a water separator, and add 300 parts of N-methylpyrrolidone and 100 parts of xylene. Stir well, place in an oil bath at 160°C for reflux for 4 hours, and filter under reduced pressure to completely remove water and xylene from the solution to obtain solution I. (2) Add epoxy resin E51 and methacrylic acid to a flask, and add 100 parts of N-methylpyrrolidone. React at 130℃ for 7 hours to obtain solution II. (3) Add solution I, solution II and azobisisobutyronitrile to a flask and react at 80°C for 3 hours. Add diethanolamine and react at 105°C for 3 hours. Add curing agent and neutralize with acetic acid to obtain modified epoxy resin. The molar ratio of the polymerization product in solution I to the epoxy resin in solution II is 1:

1.

2. A modified epoxy resin, characterized in that, The raw materials prepared by weight are: 200 parts 4,4-diaminodiphenyl ether, 328 parts norbornene adienoic anhydride, 400 parts solvent A, 392 parts epoxy resin, 86 parts methacrylic acid, 100 parts solvent B, 4 parts azobisisobutyronitrile, 105 parts diethanolamine, 200 parts curing agent, and 70 parts neutralizing agent. Solvent A is N-methylpyrrolidone and xylene in a mass ratio of 3:1; Solvent B is N-methylpyrrolidone; The epoxy resin is epoxy resin E51; The neutralizing agent is acetic acid; The curing agent is toluene diisocyanate; The preparation method of the modified epoxy resin includes the following steps: (1) Add 4,4-diaminodiphenyl ether and norborneol ediol to a flask with a water separator, and add 300 parts of N-methylpyrrolidone and 100 parts of xylene. Stir well and place in an oil bath at 160°C for reflux for 4 hours. Filter under reduced pressure to completely remove water and xylene from the solution to obtain solution I. (2) Add epoxy resin E51 and methacrylic acid to a flask, and add 100 parts of N-methylpyrrolidone. React at 130℃ for 7 hours to obtain solution II. (3) Add solution I, solution II and azobisisobutyronitrile to a flask and react at 80°C for 3 hours. Add diethanolamine and react at 105°C for 3 hours. Add curing agent and neutralize with acetic acid to obtain modified epoxy resin. The molar ratio of the polymerization product in solution I to the epoxy resin in solution II is 1:

1.

3. A modified epoxy resin, characterized in that, The raw materials prepared by weight are: 178 parts diethyltoluenediamine, 196 parts maleic anhydride, 400 parts solvent A, 392 parts epoxy resin, 86 parts methacrylic acid, 100 parts solvent B, 4 parts azobisisobutyronitrile, 105 parts diethanolamine, 200 parts curing agent, and 70 parts neutralizing agent. Solvent A is N-methylpyrrolidone and xylene in a mass ratio of 3:1; Solvent B is N-methylpyrrolidone; The epoxy resin is epoxy resin E54; The neutralizing agent is acetic acid; The curing agent is toluene diisocyanate; The preparation method of the modified epoxy resin includes the following steps: (1) Add diethyltoluene diamine and maleic anhydride to a flask equipped with a water separator, and add 300 parts of N-methylpyrrolidone and 100 parts of xylene. Stir well, place in an oil bath at 160°C for reflux for 4 hours, and filter under reduced pressure to completely remove water and xylene from the solution to obtain solution I. (2) Add epoxy resin E54 and methacrylic acid to a flask, and add 100 parts of N-methylpyrrolidone. React at 130℃ for 7 hours to obtain solution II. (3) Add solution I, solution II and azobisisobutyronitrile to a flask and react at 80°C for 3 hours. Add diethanolamine and react at 105°C for 3 hours. Add curing agent and neutralize with acetic acid to obtain modified epoxy resin. The molar ratio of the polymerization product in solution I to the epoxy resin in solution II is 1:

1.

4. An application of the modified epoxy resin according to any one of claims 1-3, characterized in that, It is used in electrophoretic paint, architectural coatings, engineering plastics and composite materials.

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