An epoxy resin and its preparation method

Abstract

The present application relates to the technical field of epoxy resins, and specifically discloses an epoxy resin and a preparation method thereof, comprising the following raw materials in parts by weight: 95 - 133 parts of a functionalized epoxy resin component, 16 - 32 parts of a curing enhancer, 3.6 - 7.4 parts of a curing accelerator, 0.9 - 1.3 parts of a photoinitiator, and 420 - 560 parts of a solvent; in the present application, a functionalized epoxy resin component and a curing enhancer are added. The functionalized epoxy resin component has a benzene ring, a flexible long-chain alkane structure, a carbon-nitrogen double bond, a flexible long-chain alkane structure, an ester group, and an epoxy group. It can not only entangle and knot with the molecular chain structure of the curing enhancer to form an interpenetrating molecular network structure that entangles with each other, but also has reversible dynamic chemical bonds. At the same time, the curing enhancer has a mercapto group and an amino group that can chemically crosslink with the functionalized epoxy resin component and form hydrogen bond interactions. Through the action of the above various structures, the strength, self-repairability, and degradability of the epoxy resin are improved.

Description

Technical Field

[0001] This application relates to the technical field of epoxy resins, and more specifically, it relates to an epoxy resin and a preparation method thereof. Background Art

[0002] Epoxy resin is a thermosetting polymer with two or more epoxy groups. Due to its small curing shrinkage rate and coefficient of thermal expansion, good dimensional stability, good processability, low cost, and excellent comprehensive performance, it is widely used in packaging materials.

[0003] However, since epoxy resin forms an insoluble and infusible three-dimensional network structure after being cured by a curing agent, it becomes solid waste with a slow degradation rate in the natural environment after use. At the same time, epoxy resin is inevitably subjected to external stimuli such as heat, mechanical, chemical, and ultraviolet light irradiation during use, which causes local damage or microcracks inside the epoxy resin. The expansion of microcracks ultimately leads to the rupture of the epoxy resin, greatly reducing its use value and safety.

[0004] Therefore, in order to better utilize epoxy resin, it is urgent to develop an epoxy resin with high strength, degradability, and self-healing performance. Summary of the Invention

[0005] In order to solve the problems mentioned in the above background art, this application provides an epoxy resin and a preparation method thereof.

[0006] An epoxy resin, comprising the following raw materials in parts by weight: 95 - 133 parts of a functionalized epoxy resin component, 16 - 32 parts of a curing enhancer, 3.6 - 7.4 parts of a curing accelerator, and 0.9 - 1.3 parts of a photoinitiator;

[0007] The preparation method of this epoxy resin comprises the following steps:

[0008] Stir the functionalized epoxy resin component, the curing enhancer, and the photoinitiator evenly, heat up to 42 - 46 °C, irradiate with ultraviolet light for 14 - 18 min while stirring, then add the curing accelerator, heat up to 54 - 62 °C, continue to stir for 32 - 46 min, and perform rotary evaporation to obtain the epoxy resin.

[0009] Stirring the functionalized epoxy resin component, the curing enhancer, and the photoinitiator evenly specifically means adding the functionalized epoxy resin component, the curing enhancer, and the photoinitiator into 420 - 560 parts of a solvent and stirring for 22 - 30 min.

[0010] Preferably, the solvent is at least one of anhydrous methanol, ethyl acetate, and tetrahydrofuran.

[0011] Preferably, the curing accelerator is at least one of 1-benzylbenzene-2-ethylimidazole, 2-ethyl-4-methylimidazole, and 1-aminoethyl-2-methylimidazole.

[0012] Preferably, the photoinitiator is 1-hydroxycyclohexyl phenyl ketone.

[0013] Preferably, the functionalized epoxy resin component is prepared by the following steps:

[0014] Step A1: Add 2,4-dihydroxybenzaldehyde and ethanolamine to absolute ethanol, stir evenly, then add glacial acetic acid, heat up to reflux, stir and react for 5-7 h, perform rotary evaporation, washing, and drying to obtain the Schiff base monomer. Among them, the mass ratio of 2,4-dihydroxybenzaldehyde, ethanolamine, absolute ethanol, and glacial acetic acid is (4-6):(2.6-3.4):(42-56):(0.06-0.1). During the above reaction process, using absolute ethanol as the solvent and glacial acetic acid as the catalyst, the aldehyde group on 2,4-dihydroxybenzaldehyde reacts with the amino group on ethanolamine to undergo a Schiff condensation reaction to obtain the Schiff base monomer;

[0015] The equation of this reaction is as follows:

[0016] ;

[0017] Step A2: Add the Schiff base monomer, p-toluenesulfonic acid, and p-hydroxycinnamic acid to absolute ethanol, heat up to 35-45 °C, stir evenly, then heat up to reflux, and continue to stir and react for 2-4 h. Perform rotary evaporation, washing, and drying to obtain the modified monomer. Among them, the mass ratio of the Schiff base monomer, p-toluenesulfonic acid, p-hydroxycinnamic acid, and absolute ethanol is (4.2-5.6):(0.12-0.24):(3.8-5.0):(54-66). During the above reaction process, using absolute ethanol as the solvent, the active hydroxyl group on the Schiff base monomer reacts with the carboxyl group on p-hydroxycinnamic acid to undergo an esterification reaction to obtain the modified monomer. The equation of this reaction is as follows:

[0018] ;

[0019] Step A3: Ultrasonically disperse the modified monomer in methyl isobutyl ketone, heat up to 86-92 °C while stirring, then add tetrabutylammonium bromide and toluene, dropwise add epichlorohydrin, and control the dropping to be completed within 10 min. After dropping, stir and react for 3.6-4.2 h. After the reaction is completed, cool to room temperature, dropwise add the alkali solution while stirring, control the dropping to be completed within 30 min, continue to stir for 0.6-0.8 h, dropwise add the alkali solution again, control the dropping to be completed within 30 min, and continue to stir for 1.8-2.2 h. Perform vacuum filtration, washing, and drying to obtain the functionalized epoxy resin component. The equation of this reaction is as follows:

[0020] ;

[0021] Among them, the mass ratio of the modified monomer, methyl isobutyl ketone, tetrabutylammonium bromide, toluene, epichlorohydrin and the total amount of the lye is (5.4 - 6.6):(56 - 64):(0.04 - 0.06):(6 - 10):(2.4 - 3.0):(22 - 26). The lye added for the first time is an aqueous sodium hydroxide solution with a mass fraction of 40 - 50%, and the lye added for the second time is an aqueous sodium hydroxide solution with a mass fraction of 32 - 36%. The masses of the lye added twice are the same. During the above reaction process, using methyl isobutyl ketone as the solvent, tetrabutylammonium bromide as the catalyst, and toluene as the dehydrating agent, the phenolic hydroxyl group on the modified monomer first undergoes an addition reaction with epichlorohydrin, and then under the action of the base, closes the ring to remove hydrogen chloride to obtain a functionalized epoxy resin component.

[0022] Preferably, the curing enhancer is prepared by the following steps:

[0023] Step B1: Add L-cysteine, trifluoromethanesulfonic acid and 3,3'-dithiodipropionic acid into anhydrous DMF, heat up to 35 - 45°C, stir evenly, then heat up to 72 - 84°C, and continue to stir and react for 3.4 - 4.6 h. Rotate and evaporate, wash, and dry to obtain a dithiol monomer. Among them, the mass ratio of L-cysteine, trifluoromethanesulfonic acid, 3,3'-dithiodipropionic acid and anhydrous DMF is (3.6 - 4.4):(0.03 - 0.05):(2.1 - 2.7):(50 - 60). During the above reaction process, using anhydrous DMF as the solvent, the active amino group on L-cysteine undergoes an esterification reaction with the carboxyl group on 3,3'-dithiodipropionic acid to obtain a dithiol monomer. During the reaction process, control the amount of substance of L-cysteine to be slightly higher than twice the equivalent of 3,3'-dithiodipropionic acid, so that the carboxyl group on 3,3'-dithiodipropionic acid can be fully consumed. The equation of this reaction is shown as follows:

[0024] ;

[0025] Step B2: Add diethylenetriamine and dithiol monomer into anhydrous DMF, stir evenly, and dropwise add the mixed solution a of N,N-dicyclohexylcarbodiimide, 4-dimethylaminopyridine and anhydrous DMF while stirring. After dropping, raise the temperature to 72-78 °C and stir for reaction for 3-5 h. After the reaction is completed, filter, wash and dry to obtain the curing enhancer. Among them, the mass ratio of diethylenetriamine, dithiol monomer, anhydrous DMF and the mixed solution a is (6-8):(20-26):(80-90):(30-40). In the mixed solution a, the mass ratio of N,N-dicyclohexylcarbodiimide, 4-dimethylaminopyridine and anhydrous DMF is (5.6-7.2):(3.6-4.6):(23-27). In the above reaction process, using anhydrous DMF as the solvent, N,N-dicyclohexylcarbodiimide as the dehydrating agent, 4-dimethylaminopyridine as the acylating agent, diethylenetriamine and dithiol monomer undergo amidation reaction to obtain the curing enhancer. The chemical equation of this reaction is as follows:

[0026] 。

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] (1) In order to improve the strength of epoxy resin and at the same time prepare an epoxy resin material with self-healing performance, the present invention starts from two aspects. One is to add a functionalized epoxy resin component to the raw materials. This functionalized epoxy resin component contains a benzene ring, a flexible long-chain alkane structure, a carbon-nitrogen double bond, a flexible long-chain alkane structure, an ester group and an epoxy group. Based on the presence of the benzene ring and the flexible long-chain alkane structure, the toughness and impact resistance of the epoxy resin are improved. And the flexible long-chain alkane structure can entangle and intertwine with the molecular chain structure of the curing enhancer to form an interpenetrating molecular network structure of mutual entanglement, making it have good compatibility with the curing enhancer and improving the toughness of the epoxy resin. The carbon-nitrogen double bond has reversible dynamic chemical bonds, and at the same time the ester group can form multiple hydrogen bond interactions with the ester group and amino group in the curing enhancer. Through the above joint action, cracks on the micron scale can be repaired, and the self-healing performance of the epoxy resin can be improved. The presence of the epoxy group can form chemical bonding with the amino group in the curing enhancer, further improving the toughness of the epoxy resin. The other is to add a curing enhancer. On the one hand, the curing enhancer contains a mercapto group that can chemically crosslink with the functionalized epoxy resin component. On the other hand, the surface of the modified reinforcing agent is grafted with a disulfide bond with low bond energy and dynamic action. Introducing it into the epoxy resin can cooperate with the functionalized epoxy resin component to jointly improve the strength and self-healing performance of the epoxy resin.

[0029] (2) The epoxy resin prepared in this application contains degradable structural units such as ester groups, disulfide bonds, and Schiff base structures, and can be degraded under mild conditions to achieve resource recycling and meet the needs of social sustainable development. Detailed implementation mode

[0030] To make the implementation modes of this application easier to understand, the following will specifically describe this application in combination with specific embodiments. These embodiments are only illustrative and are not limited to the application scope of this application.

[0031] The following further details this application in combination with examples and comparative examples.

[0032] Preparation Examples 1-3 and Comparative Preparation Examples 1-2 provide methods for preparing functionalized epoxy resin components.

[0033] Preparation Example 1

[0034] This preparation example provides a functionalized epoxy resin component, which is prepared by the following steps:

[0035] Step A1: Add 2,4-dihydroxybenzaldehyde and ethanolamine to absolute ethanol, stir at a rotation speed of 500 rpm for 18 min until uniform, then add glacial acetic acid, heat up to reflux, maintain the rotation speed unchanged, and continue stirring and reacting for 5 h. Control the rotary evaporation temperature at 64 °C, rotary evaporate until absolute ethanol is removed, wash 3 times with deionized water, and dry at 55 °C to constant weight to obtain the Schiff base monomer. Among them, the mass ratio of 2,4-dihydroxybenzaldehyde, ethanolamine, absolute ethanol, and glacial acetic acid is 4:2.6:42:0.06;

[0036] Step A2: Add the Schiff base monomer, p-toluenesulfonic acid, and p-hydroxycinnamic acid to absolute ethanol, heat up to 35 °C, stir at a rotation speed of 550 rpm for 24 min until uniform, then heat up to reflux, and continue stirring and reacting for 2 h. Control the rotary evaporation temperature at 66 °C, rotary evaporate until absolute ethanol is removed, wash 3 times with deionized water, and dry at 62 °C to constant weight to obtain the modified monomer. Among them, the mass ratio of the Schiff base monomer, p-toluenesulfonic acid, p-hydroxycinnamic acid, and absolute ethanol is 4.2:0.12:3.8:54;

[0037] Step A3: Ultrasonically disperse the modified monomer in methyl isobutyl ketone, control the ultrasonic frequency at 35 kHz, ultrasonic power at 550 w, ultrasonic for 24 min, control the rotation speed at 600 rpm, heat up to 86 °C while stirring, then add tetrabutylammonium bromide and toluene, dropwise add epichlorohydrin, control to finish dropping within 10 min. After dropping, stir and react for 3.6 h. After the reaction ends, cool to room temperature, dropwise add the alkali solution while stirring, control to finish dropping within 30 min, continue stirring for 0.6 h, dropwise add the alkali solution again, control to finish dropping within 30 min, continue stirring for 1.8 h, carry out vacuum filtration, wash 3 times with absolute ethanol and deionized water in sequence, dry at 68 °C to constant weight to obtain the functionalized epoxy resin component. Among them, the mass ratio of the modified monomer, methyl isobutyl ketone, tetrabutylammonium bromide, toluene, epichlorohydrin and the total amount of the alkali solution is 5.4:56:0.04:6:2.4:22. The alkali solution added for the first time is a 40% sodium hydroxide aqueous solution, and the alkali solution added for the second time is a 32% sodium hydroxide aqueous solution. The masses of the alkali solutions added twice are the same.

[0038] Preparation Example 2

[0039] This preparation example provides a functionalized epoxy resin component, which is prepared by the following steps:

[0040] Step A1: Add 2,4-dihydroxybenzaldehyde and ethanolamine to absolute ethanol, stir at a rotation speed of 600 rpm for 22 min until uniform, then add glacial acetic acid, heat up to reflux, stir and react for 6 h, control the rotary evaporation temperature at 68 °C, rotary evaporate until absolute ethanol is removed, wash 4 times with deionized water, dry at 60 °C to constant weight to obtain the Schiff base monomer. Among them, the mass ratio of 2,4-dihydroxybenzaldehyde, ethanolamine, absolute ethanol and glacial acetic acid is 5:3.0:49:0.08;

[0041] Step A2: Add the Schiff base monomer, p-toluenesulfonic acid and p-hydroxycinnamic acid to absolute ethanol, heat up to 40 °C, stir at a rotation speed of 580 rpm for 26 min until uniform, then heat up to reflux, continue stirring and reacting for 3 h, control the rotary evaporation temperature at 72 °C, rotary evaporate until absolute ethanol is removed, wash 4 times with deionized water, dry at 64 °C to constant weight to obtain the modified monomer. Among them, the mass ratio of the Schiff base monomer, p-toluenesulfonic acid, p-hydroxycinnamic acid and absolute ethanol is 4.9:0.18:4.4:60;

[0042] Step A3: Ultrasonically disperse the modified monomer in methyl isobutyl ketone, control the ultrasonic frequency at 40 kHz, ultrasonic power at 600 w, ultrasonic for 26 min, control the rotation speed at 650 rpm, heat up to 89 °C while stirring, then add tetrabutylammonium bromide and toluene, dropwise add epichlorohydrin, control to finish dropping within 10 min. After dropping, stir and react for 3.9 h. After the reaction ends, cool to room temperature, dropwise add the alkali solution while stirring, control to finish dropping within 30 min, continue stirring for 0.7 h, dropwise add the alkali solution again, control to finish dropping within 30 min, continue stirring for 2.0 h, carry out vacuum filtration, wash 4 times with absolute ethanol and deionized water in sequence, dry at 72 °C to constant weight to obtain the functionalized epoxy resin component. Among them, the mass ratio of the modified monomer, methyl isobutyl ketone, tetrabutylammonium bromide, toluene, epichlorohydrin and the total amount of the alkali solution is 6.0:60:0.05:8:2.7:24. The alkali solution added for the first time is an aqueous sodium hydroxide solution with a mass fraction of 45%, and the alkali solution added for the second time is an aqueous sodium hydroxide solution with a mass fraction of 34%. The masses of the alkali solutions added twice are the same.

[0043] Preparation Example 3

[0044] This preparation example provides a functionalized epoxy resin component, which is prepared by the following steps:

[0045] Step A1: Add 2,4-dihydroxybenzaldehyde and ethanolamine to absolute ethanol, stir at a rotation speed of 700 rpm for 26 min until uniform, then add glacial acetic acid, heat up to reflux, stir and react for 7 h, control the rotary evaporation temperature at 74 °C, rotary evaporate until absolute ethanol is removed, wash 5 times with deionized water, dry at 65 °C to constant weight to obtain the Schiff base monomer. Among them, the mass ratio of 2,4-dihydroxybenzaldehyde, ethanolamine, absolute ethanol and glacial acetic acid is 6:3.4:56:0.1;

[0046] Step A2: Add the Schiff base monomer, p-toluenesulfonic acid and p-hydroxycinnamic acid to absolute ethanol, heat up to 45 °C, stir at a rotation speed of 610 rpm for 30 min until uniform, then heat up to reflux, continue stirring and reacting for 4 h, control the rotary evaporation temperature at 78 °C, rotary evaporate until absolute ethanol is removed, wash 5 times with deionized water, dry at 66 °C to constant weight to obtain the modified monomer. Among them, the mass ratio of the Schiff base monomer, p-toluenesulfonic acid, p-hydroxycinnamic acid and absolute ethanol is 5.6:0.24:5.0:66;

[0047] Step A3: Ultrasonically disperse the modified monomer in methyl isobutyl ketone. Control the ultrasonic frequency at 46 kHz, the ultrasonic power at 650 W, and ultrasonicate for 28 min. While stirring at a speed of 700 rpm, heat up to 92 °C. Then add tetrabutylammonium bromide and toluene, and dropwise add epichlorohydrin, controlling to finish dropping within 10 min. After dropping, stir and react for 4.2 h. After the reaction ends, cool to room temperature, and while stirring, dropwise add the alkali solution, controlling to finish dropping within 30 min. Continue stirring for 0.8 h, then dropwise add the alkali solution again, controlling to finish dropping within 30 min. Continue stirring for 2.2 h. Perform vacuum filtration, wash 5 times successively with absolute ethanol and deionized water, and dry at 76 °C to constant weight to obtain the functionalized epoxy resin component. Among them, the mass ratio of the modified monomer, methyl isobutyl ketone, tetrabutylammonium bromide, toluene, epichlorohydrin, and the total amount of the alkali solution is 6.6:64:0.06:10:3.0:26. The alkali solution added for the first time is a 50% sodium hydroxide aqueous solution by mass, and the alkali solution added for the second time is a 36% sodium hydroxide aqueous solution by mass. The masses of the alkali solutions added twice are the same.

[0048] Comparative Preparation Example 1

[0049] This comparative preparation example provides a functionalized epoxy resin component, which is prepared by the following steps:

[0050] Step A1: Add hydroxycitronellal and ethanolamine to absolute ethanol, stir at a speed of 500 rpm for 18 min until uniform, then add glacial acetic acid, heat up to reflux, maintain the rotation speed unchanged, continue stirring and reacting for 5 h, control the rotary evaporation temperature at 64 °C, rotary evaporate until absolute ethanol is removed, wash 3 times with deionized water, and dry at 55 °C to constant weight to obtain the Schiff base monomer. Among them, the mass ratio of hydroxycitronellal, ethanolamine, absolute ethanol, and glacial acetic acid is 4:2.6:42:0.06;

[0051] Step A2: Add the Schiff base monomer, p-toluenesulfonic acid, and p-hydroxycinnamic acid to absolute ethanol, heat up to 35 °C, stir at a speed of 550 rpm for 24 min until uniform, then heat up to reflux, continue stirring and reacting for 2 h, control the rotary evaporation temperature at 66 °C, rotary evaporate until absolute ethanol is removed, wash 3 times with deionized water, and dry at 62 °C to constant weight to obtain the modified monomer. Among them, the mass ratio of the Schiff base monomer, p-toluenesulfonic acid, p-hydroxycinnamic acid, and absolute ethanol is 4.2:0.12:3.8:54;

[0052] Step A3: Ultrasonically disperse the modified monomer in methyl isobutyl ketone. Control the ultrasonic frequency at 35 kHz, the ultrasonic power at 550 W, and ultrasonicate for 24 min. Control the rotation speed at 600 rpm, heat up to 86°C while stirring, then add tetrabutylammonium bromide and toluene, and dropwise add epichlorohydrin, controlling to finish dropping within 10 min. After dropping, stir and react for 3.6 h. After the reaction ends, cool to room temperature, dropwise add the lye while stirring, controlling to finish dropping within 30 min, continue stirring for 0.6 h, dropwise add the lye again, controlling to finish dropping within 30 min, and continue stirring for 1.8 h. Perform vacuum filtration, wash three times with absolute ethanol and deionized water in sequence, and dry at 68°C to constant weight to obtain the functionalized epoxy resin component. Among them, the mass ratio of the modified monomer, methyl isobutyl ketone, tetrabutylammonium bromide, toluene, epichlorohydrin, and the total amount of lye is 5.4:56:0.04:6:2.4:22. The lye added for the first time is a 40% sodium hydroxide aqueous solution by mass, and the lye added for the second time is a 32% sodium hydroxide aqueous solution by mass. The masses of the lye added twice are the same.

[0053] Comparative Preparation Example 2

[0054] This comparative preparation example provides a functionalized epoxy resin component, which is prepared by the following steps:

[0055] Step A1: Add 2,4-dihydroxybenzaldehyde and ethanolamine to absolute ethanol, stir at a rotation speed of 500 rpm for 18 min until uniform, then add glacial acetic acid, heat up to reflux, maintain the rotation speed unchanged, continue stirring and reacting for 5 h, control the rotary evaporation temperature at 64°C, rotary evaporate until absolute ethanol is removed, wash three times with deionized water, and dry at 55°C to constant weight to obtain the Schiff base monomer. Among them, the mass ratio of 2,4-dihydroxybenzaldehyde, ethanolamine, absolute ethanol, and glacial acetic acid is 4:2.6:42:0.06;

[0056] Step A2: Add the Schiff base monomer, p-toluenesulfonic acid, and 2,2-dimethyl-3-hydroxypropionic acid to absolute ethanol, heat up to 35°C, stir at a rotation speed of 550 rpm for 24 min until uniform, then heat up to reflux, continue stirring and reacting for 2 h, control the rotary evaporation temperature at 66°C, rotary evaporate until absolute ethanol is removed, wash three times with deionized water, and dry at 62°C to constant weight to obtain the modified monomer. Among them, the mass ratio of the Schiff base monomer, p-toluenesulfonic acid, 2,2-dimethyl-3-hydroxypropionic acid, and absolute ethanol is 4.2:0.12:3.8:54;

[0057] Step A3: Ultrasonically disperse the modified monomer in methyl isobutyl ketone, control the ultrasonic frequency at 35 kHz, ultrasonic power at 550 w, sonicate for 24 min, control the rotation speed at 600 rpm, heat up to 86 °C while stirring, then add tetrabutylammonium bromide and toluene, dropwise add epichlorohydrin, control to finish dropping within 10 min. After dropping, stir and react for 3.6 h. After the reaction ends, cool to room temperature, dropwise add the lye while stirring, control to finish dropping within 30 min, continue stirring for 0.6 h, dropwise add the lye again, control to finish dropping within 30 min, continue stirring for 1.8 h, carry out vacuum filtration, wash with absolute ethanol and deionized water 3 times in sequence, dry at 68 °C to constant weight to obtain the functionalized epoxy resin component. Among them, the mass ratio of the modified monomer, methyl isobutyl ketone, tetrabutylammonium bromide, toluene, epichlorohydrin and the total amount of lye is 5.4:56:0.04:6:2.4:22. The first lye added is an aqueous sodium hydroxide solution with a mass fraction of 40%, and the second lye added is an aqueous sodium hydroxide solution with a mass fraction of 32%. The masses of the lye added twice are the same.

[0058] Preparation Examples 4-6 and Comparative Preparation Examples 3-4 provide a curing enhancer.

[0059] Preparation Example 4

[0060] This preparation example provides a curing enhancer, which is prepared by the following steps:

[0061] Step B1: Add L-cysteine, trifluoromethanesulfonic acid and 3,3'-dithiobispropionic acid to anhydrous DMF, heat up to 35 °C, stir at a rotation speed of 620 rpm for 20 min until homogeneous, then heat up to 72 °C, maintain the rotation speed unchanged, continue stirring and reacting for 3.4 h, control the rotary evaporation temperature at 81 °C, rotary evaporate to remove anhydrous DMF, then wash with absolute ethanol and deionized water 3 times in sequence, dry at 66 °C to constant weight to obtain the disulfide monomer. Among them, the mass ratio of L-cysteine, trifluoromethanesulfonic acid, 3,3'-dithiobispropionic acid and anhydrous DMF is 3.6:0.03:2.1:50;

[0062] Step B2: Add diethylenetriamine and the disulfide monomer to anhydrous DMF, stir at a rotation speed of 720 rpm for 18 min until homogeneous, dropwise add the mixed solution a of N,N'-dicyclohexylcarbodiimide, 4-dimethylaminopyridine and anhydrous DMF while stirring. After dropping, heat up to 72 °C, maintain the rotation speed unchanged, continue stirring and reacting for 3 h. After the reaction ends, carry out suction filtration, wash the filter cake with absolute ethanol and deionized water 3 times in sequence, dry at 70 °C to constant weight to obtain the curing enhancer. Among them, the mass ratio of diethylenetriamine, the disulfide monomer, anhydrous DMF and the mixed solution a is 6:20:80:30. In the mixed solution a, the mass ratio of N,N'-dicyclohexylcarbodiimide, 4-dimethylaminopyridine and anhydrous DMF is 5.6:3.6:23.

[0063] Preparation Example 5

[0064] This preparation example provides a curing enhancer, which is prepared by the following steps:

[0065] Step B1: Add L-cysteine, trifluoromethanesulfonic acid, and 3,3'-dithiobispropionic acid into anhydrous DMF, heat up to 40 °C, stir at a rotation speed of 660 rpm for 24 min until uniform, stir evenly, then heat up to 78 °C, maintain the rotation speed unchanged, and continue to stir and react for 4.0 h. Control the rotary evaporation temperature at 85 °C, rotary evaporate to remove anhydrous DMF, then wash with anhydrous ethanol and deionized water 4 times successively, and dry at 70 °C to constant weight to obtain a disulfide monomer. Among them, the mass ratio of L-cysteine, trifluoromethanesulfonic acid, 3,3'-dithiobispropionic acid, and anhydrous DMF is 4.0:0.04:2.4:55;

[0066] Step B2: Add diethylenetriamine and the disulfide monomer into anhydrous DMF, stir at a rotation speed of 760 rpm for 22 min until uniform, while stirring, dropwise add a mixed solution a of N,N'-dicyclohexylcarbodiimide, 4-dimethylaminopyridine, and anhydrous DMF. After dropping, heat up to 75 °C, maintain the rotation speed unchanged, and continue to stir and react for 4 h. After the reaction is completed, perform suction filtration, wash the filter cake with anhydrous ethanol and deionized water 4 times successively, and dry at 74 °C to constant weight to obtain a curing enhancer. Among them, the mass ratio of diethylenetriamine, the disulfide monomer, anhydrous DMF, and the mixed solution a is 7:23:85:35. In the mixed solution a, the mass ratio of N,N'-dicyclohexylcarbodiimide, 4-dimethylaminopyridine, and anhydrous DMF is 6.4:4.1:25.

[0067] Preparation Example 6

[0068] This preparation example provides a curing enhancer, which is prepared by the following steps:

[0069] Step B1: Add L-cysteine, trifluoromethanesulfonic acid, and 3,3'-dithiobispropionic acid into anhydrous DMF, heat up to 45 °C, stir at a rotation speed of 700 rpm for 28 min until uniform, then heat up to 84 °C, maintain the rotation speed unchanged, and continue to stir and react for 4.6 h. Control the rotary evaporation temperature at 89 °C, rotary evaporate to remove anhydrous DMF, then wash with anhydrous ethanol and deionized water 5 times successively, and dry at 74 °C to constant weight to obtain a disulfide monomer. Among them, the mass ratio of L-cysteine, trifluoromethanesulfonic acid, 3,3'-dithiobispropionic acid, and anhydrous DMF is 4.4:0.05:2.7:60;

[0070] Step B2: Add diethylenetriamine and dithiol monomer into anhydrous DMF, stir at 800 rpm for 26 min until homogeneous, while stirring, dropwise add the mixed solution a of N,N'-dicyclohexylcarbodiimide, 4-dimethylaminopyridine and anhydrous DMF. After dropping, raise the temperature to 78 °C, maintain the rotation speed unchanged, and continue to stir and react for 5 h. After the reaction is completed, perform suction filtration. The filter cake is washed 5 times successively with anhydrous ethanol and deionized water, and dried at 78 °C to constant weight to obtain the curing enhancer. Among them, the mass ratio of diethylenetriamine, dithiol monomer, anhydrous DMF and the mixed solution a is 8:26:90:40. In the mixed solution a, the mass ratio of N,N'-dicyclohexylcarbodiimide, 4-dimethylaminopyridine and anhydrous DMF is 7.2:4.6:27.

[0071] Comparative Preparation Example 3

[0072] This comparative preparation example provides a curing enhancer, which is prepared by the following steps:

[0073] Step B1: Add L-cysteine, trifluoromethanesulfonic acid and 3,3'-thiodipropionic acid into anhydrous DMF, raise the temperature to 35 °C, stir at 620 rpm for 20 min until homogeneous, then raise the temperature to 72 °C, maintain the rotation speed unchanged, and continue to stir and react for 3.4 h. Control the rotary evaporation temperature at 81 °C, rotary evaporate to remove anhydrous DMF, and then wash 3 times successively with anhydrous ethanol and deionized water, and dry at 66 °C to constant weight to obtain the dithiol monomer. Among them, the mass ratio of L-cysteine, trifluoromethanesulfonic acid, 3,3'-thiodipropionic acid and anhydrous DMF is 3.6:0.03:2.1:50;

[0074] Step B2: Add diethylenetriamine and dithiol monomer into anhydrous DMF, stir at 720 rpm for 18 min until homogeneous, while stirring, dropwise add the mixed solution a of N,N'-dicyclohexylcarbodiimide, 4-dimethylaminopyridine and anhydrous DMF. After dropping, raise the temperature to 72 °C, maintain the rotation speed unchanged, and continue to stir and react for 3 h. After the reaction is completed, perform suction filtration. The filter cake is washed 3 times successively with anhydrous ethanol and deionized water, and dried at 70 °C to constant weight to obtain the curing enhancer. Among them, the mass ratio of diethylenetriamine, dithiol monomer, anhydrous DMF and the mixed solution a is 6:20:80:30. In the mixed solution a, the mass ratio of N,N'-dicyclohexylcarbodiimide, 4-dimethylaminopyridine and anhydrous DMF is 5.6:3.6:23.

[0075] Comparative Preparation Example 4

[0076] This comparative preparation example provides a curing enhancer, which is prepared by the following steps:

[0077] Step B1: Add glycine, trifluoromethanesulfonic acid, and 3,3'-dithiobispropionic acid into anhydrous DMF, heat up to 35°C, stir at a speed of 620 rpm for 20 min until homogeneous, then heat up to 72°C, keep the rotation speed unchanged, continue to stir and react for 3.4 h, control the rotary evaporation temperature at 81°C, rotary evaporate to remove anhydrous DMF, and then wash with anhydrous ethanol and deionized water three times each, dry at 66°C to constant weight to obtain the dithiol monomer. Among them, the mass ratio of glycine, trifluoromethanesulfonic acid, 3,3'-dithiobispropionic acid, and anhydrous DMF is 3.6:0.03:2.1:50;

[0078] Step B2: Add diethylenetriamine and the dithiol monomer into anhydrous DMF, stir at a speed of 720 rpm for 18 min until homogeneous, dropwise add the mixed solution a of N,N'-dicyclohexylcarbodiimide, 4-dimethylaminopyridine, and anhydrous DMF while stirring. After dropping, heat up to 72°C, keep the rotation speed unchanged, continue to stir and react for 3 h. After the reaction, perform suction filtration, wash the filter cake with anhydrous ethanol and deionized water three times each, dry at 70°C to constant weight to obtain the curing enhancer. Among them, the mass ratio of diethylenetriamine, the dithiol monomer, anhydrous DMF, and the mixed solution a is 6:20:80:30. In the mixed solution a, the mass ratio of N,N'-dicyclohexylcarbodiimide, 4-dimethylaminopyridine, and anhydrous DMF is 5.6:3.6:23.

[0079] Examples 1-3 and Comparative Examples 1-4 provide an epoxy resin and its preparation method.

[0080] Example 1

[0081] This example provides an epoxy resin and its preparation method. The epoxy resin includes the following raw materials in parts by weight: 95 parts of the functionalized epoxy resin component prepared in Preparation Example 1, 16 parts of the curing enhancer prepared in Preparation Example 4, 3.6 parts of 1-benzylbenzene-2-ethylimidazole, 0.9 part of 1-hydroxycyclohexyl phenyl ketone, and 420 parts of anhydrous methanol;

[0082] The preparation method of this epoxy resin includes the following steps:

[0083] Add the functionalized epoxy resin component, the curing enhancer, and 1-hydroxycyclohexyl phenyl ketone into anhydrous methanol, stir at a speed of 660 rpm for 22 min until homogeneous, heat up to 42°C, irradiate with ultraviolet light having a wavelength peak of 365 nm and an intensity of 80 mw / cm 2 for 14 min while stirring, then add 1-benzylbenzene-2-ethylimidazole, heat up to 54°C, reduce the rotation speed to 500 rpm, continue to stir for 32 min, control the rotary evaporation temperature at 62°C, rotary evaporate to remove anhydrous methanol to obtain the epoxy resin.

[0084] Example 2

[0085] This embodiment provides an epoxy resin and a preparation method thereof. The epoxy resin comprises the following raw materials in parts by weight: 114 parts of the functionalized epoxy resin component prepared in Preparation Example 2, 24 parts of the curing enhancer prepared in Preparation Example 5, 5.5 parts of 2-ethyl-4-methylimidazole, 1.1 parts of 1-hydroxycyclohexyl phenyl ketone, and 490 parts of ethyl acetate;

[0086] The preparation method of the epoxy resin comprises the following steps:

[0087] Add the functionalized epoxy resin component, the curing enhancer, and 1-hydroxycyclohexyl phenyl ketone into ethyl acetate, stir at a rotation speed of 700 rpm for 26 min until homogeneous, heat up to 44 °C, irradiate under ultraviolet light with a wavelength peak of 365 nm and an intensity of 80 mw / cm 2 for 16 min while stirring, then add 2-ethyl-4-methylimidazole, heat up to 58 °C, reduce the rotation speed to 520 rpm, continue stirring for 39 min, control the rotary evaporation temperature at 74 °C, and rotary evaporate until ethyl acetate is removed to obtain the epoxy resin.

[0088] Example 3

[0089] This embodiment provides an epoxy resin and a preparation method thereof. The epoxy resin comprises the following raw materials in parts by weight: 133 parts of the functionalized epoxy resin component prepared in Preparation Example 3, 32 parts of the curing enhancer prepared in Preparation Example 6, 7.4 parts of 1-aminoethyl-2-methylimidazole, 1.3 parts of 1-hydroxycyclohexyl phenyl ketone, and 560 parts of tetrahydrofuran;

[0090] The preparation method of the epoxy resin comprises the following steps:

[0091] Add the functionalized epoxy resin component, the curing enhancer, and 1-hydroxycyclohexyl phenyl ketone into tetrahydrofuran, stir at a rotation speed of 740 rpm for 30 min until homogeneous, heat up to 46 °C, irradiate under ultraviolet light with a wavelength peak of 365 nm and an intensity of 80 mw / cm 2 for 18 min while stirring, then add 1-aminoethyl-2-methylimidazole, heat up to 62 °C, reduce the rotation speed to 540 rpm, continue stirring for 46 min, control the rotary evaporation temperature at 78 °C, and rotary evaporate until tetrahydrofuran is removed to obtain the epoxy resin.

[0092] Comparative Example 1

[0093] This comparative example provides an epoxy resin and a preparation method thereof. The epoxy resin comprises the following raw materials in parts by weight: 95 parts of the functionalized epoxy resin component prepared in Comparative Preparation Example 1, 16 parts of the curing enhancer prepared in Preparation Example 4, 3.6 parts of 1-benzylbenzene-2-ethylimidazole, 0.9 parts of 1-hydroxycyclohexyl phenyl ketone, and 420 parts of anhydrous methanol;

[0094] The preparation method of the epoxy resin comprises the following steps:

[0095] Put the functionalized epoxy resin component, the curing enhancer and 1-hydroxycyclohexyl phenyl ketone into anhydrous methanol, stir at a rotation speed of 660 rpm for 22 min until uniform, heat up to 42 °C, and irradiate under ultraviolet light with a peak wavelength of 365 nm and an intensity of 80 mw / cm 2 for 14 min while stirring, then add 1-benzylbenzene-2-ethylimidazole, heat up to 54 °C, reduce the rotation speed to 500 rpm, continue to stir for 32 min, control the rotary evaporation temperature at 62 °C, and rotary evaporate until anhydrous methanol is removed to obtain the epoxy resin.

[0096] Comparative Example 2

[0097] This comparative example provides an epoxy resin, which comprises the following raw materials in parts by weight: 95 parts of the functionalized epoxy resin component prepared in Comparative Preparation Example 2, 16 parts of the curing enhancer prepared in Preparation Example 4, 3.6 parts of 1-benzylbenzene-2-ethylimidazole, 0.9 part of 1-hydroxycyclohexyl phenyl ketone, and 420 parts of anhydrous methanol;

[0098] The preparation method of the epoxy resin comprises the following steps:

[0099] Put the functionalized epoxy resin component, the curing enhancer and 1-hydroxycyclohexyl phenyl ketone into anhydrous methanol, stir at a rotation speed of 660 rpm for 22 min until uniform, heat up to 42 °C, and irradiate under ultraviolet light with a peak wavelength of 365 nm and an intensity of 80 mw / cm 2 for 14 min while stirring, then add 1-benzylbenzene-2-ethylimidazole, heat up to 54 °C, reduce the rotation speed to 500 rpm, continue to stir for 32 min, control the rotary evaporation temperature at 62 °C, and rotary evaporate until anhydrous methanol is removed to obtain the epoxy resin.

[0100] Comparative Example 3

[0101] This comparative example provides an epoxy resin and its preparation method. The epoxy resin comprises the following raw materials in parts by weight: 95 parts of the functionalized epoxy resin component prepared in Preparation Example 1, 16 parts of the curing enhancer prepared in Comparative Preparation Example 3, 3.6 parts of 1-benzylbenzene-2-ethylimidazole, 0.9 part of 1-hydroxycyclohexyl phenyl ketone, and 420 parts of anhydrous methanol;

[0102] The preparation method of the epoxy resin comprises the following steps:

[0103] The functionalized epoxy resin component, the curing enhancer, and 1-hydroxycyclohexyl phenyl ketone were added to anhydrous methanol, stirred at 660 rpm for 22 min until homogeneous, heated to 42 °C, and irradiated under ultraviolet light with a peak wavelength of 365 nm and an intensity of 80 mw / cm 2 for 14 min while stirring, then 1-benzylbenzene-2-ethylimidazole was added, the temperature was raised to 54 °C, the rotation speed was reduced to 500 rpm, and stirring was continued for 32 min. The rotary evaporation temperature was controlled at 62 °C, and anhydrous methanol was removed by rotary evaporation to obtain the epoxy resin.

[0104] Comparative Example 4

[0105] This comparative example provides an epoxy resin and a preparation method thereof. The epoxy resin includes the following raw materials in parts by weight: 95 parts of the functionalized epoxy resin component prepared in Preparation Example 1, 16 parts of the curing enhancer prepared in Comparative Preparation Example 4, 3.6 parts of 1-benzylbenzene-2-ethylimidazole, 0.9 part of 1-hydroxycyclohexyl phenyl ketone, and 420 parts of anhydrous methanol;

[0106] The preparation method of the epoxy resin includes the following steps:

[0107] The functionalized epoxy resin component, the curing enhancer, and 1-hydroxycyclohexyl phenyl ketone were added to anhydrous methanol, stirred at 660 rpm for 22 min until homogeneous, heated to 42 °C, and irradiated under ultraviolet light with a peak wavelength of 365 nm and an intensity of 80 mw / cm 2 for 14 min while stirring, then 1-benzylbenzene-2-ethylimidazole was added, the temperature was raised to 54 °C, the rotation speed was reduced to 500 rpm, and stirring was continued for 32 min. The rotary evaporation temperature was controlled at 62 °C, and anhydrous methanol was removed by rotary evaporation to obtain the epoxy resin.

[0108] Performance Testing

[0109] The epoxy resins prepared in Examples 1-3 and Comparative Examples 1-4 were poured onto a clean polytetrafluoroethylene plate, and coated from 12 μm, 24 μm, 36 μm to 48 μm in sequence with a four-sided film applicator, pre-cured at 90 °C for 2 h, post-cured at 140 °C for 4 h, then hot-pressed at 0.4 MPa and 140 °C for 4 h, and the film was separated from the polytetrafluoroethylene plate with a scraper to obtain the samples.

[0110] 1. Mechanical Properties

[0111] The mechanical properties of the test samples, namely the tensile modulus, tensile strength, and elongation at break, were measured using an ASTM D882-12 material testing system;

[0112] Impact resistance: The impact resistance of the samples was tested according to GB / T 13525-1992;

[0113] Self-repairability: Make a scratch about 1 mm in length on the surface of the sample, heat it at 90 °C for 2 h, observe whether it is repaired, and then select the tensile strength as the evaluation parameter for the self-repair rate. According to the calculation formula of the self-repair rate, calculate the self-repair rate ɑ; Make the sample into a dumbbell shape, cut it with a blade, the scratch depth is 2 mm, put it into a 90 °C environment for heating and repairing for 2 h, conduct a tensile test on the system with a universal testing machine, the tensile rate is 2 mm / min, the test condition is room temperature, and record the experimental results. The repair efficiency (self-repair rate) is calculated as shown in formula (1):

[0114]

[0115] In formula (1), ɑ repairde is the tensile strength after scratch repair, and ɑ virgin is the initial tensile strength;

[0116] Judgment criterion for whether it is repaired: If the repair rate is greater than 30%, it is considered repaired; if it is less than or equal to 30%, it is considered not repaired;

[0117] Degradability: Respectively prepare the epoxy resins provided in Examples 1-3 and Comparative Examples 1-4 into samples with dimensions of 50 mm × 50 mm × 5 mm. Immerse each sample in 300 mL of ethanol and soak it at 110 °C for 2 h, then filter and collect the undissolved samples and weigh them after drying to calculate the degradation rate. The calculation formula of the degradation rate is as shown in formula (2):

[0118]

[0119] In formula (2), W a is the mass (g) of the epoxy resin sample before degradation, and W b is the mass (g) of the epoxy resin sample after degradation. The specific test results are shown in Table 1 below: Table 1 Performance tests of epoxy resins prepared in Examples 1-3 and Comparative Examples 1-4

[0120]

[0121] As can be seen from Table 1, compared with Comparative Examples 1-4, the epoxy resins prepared in Examples 1-3 not only have more excellent mechanical properties, but also have good self-repairability and degradation rate.

[0122] This specific embodiment is only an explanation of the present application and does not limit the present application. After reading this specification, those skilled in the art can make modifications that do not contribute creatively to this embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. An epoxy resin, characterized in that The method comprises the following raw materials in parts by weight: 95-133 parts of a functionalized epoxy resin component, 16-32 parts of a curing enhancer, 3.6-7.4 parts of a curing accelerator and 0.9-1.3 parts of a photoinitiator; The structural formula of the functionalized epoxy resin component is as follows: The functionalized epoxy resin component is firstly prepared by a Schiff condensation reaction between 2,4-dihydroxybenzaldehyde and ethanolamine to obtain a Schiff base monomer, then an esterification reaction with p-hydroxycinnamic acid to obtain a modified monomer, and finally a nucleophilic substitution reaction with epichlorohydrin to obtain the functionalized epoxy resin component. The structural formula of the curing enhancer is as follows: 。 2. An epoxy resin according to claim 1, characterized in that: The functionalized epoxy resin component is prepared by the following steps: Step A1, adding 2,4-dihydroxybenzaldehyde and ethanolamine to anhydrous ethanol, stirring evenly, then adding glacial acetic acid, heating to reflux, stirring to react for 5-7h, rotary evaporation, washing, and drying to obtain a Schiff base monomer; Step A2, adding Schiff base monomer, p-toluenesulfonic acid and p-hydroxycinnamic acid into anhydrous ethanol, heating to 35-45° C., stirring evenly, then heating to reflux, stirring and reacting for 2-4 hours, rotary evaporation, washing, and drying to obtain a modified monomer; Step A3, ultrasonically disperse the modified monomer in methyl isobutyl ketone, raise the temperature to 86-92°C while stirring, then add tetrabutylammonium bromide and toluene, add epichlorohydrin dropwise, control the dripping to be completed within 10 minutes, complete the dripping, stir and react for 3.6-4.2 hours, after the reaction is completed, cool to room temperature, add alkali solution dropwise while stirring, control the dripping to be completed within 30 minutes, continue stirring for 0.6-0.8 hours, add alkali solution dropwise again, control the dripping to be completed within 30 minutes, continue stirring for 1.8-2.2 hours, filter under reduced pressure, wash, and dry to obtain a functionalized epoxy resin component.

3. An epoxy resin according to claim 2, characterized in that: In the step A1, the mass ratio of 2,4-dihydroxybenzaldehyde, ethanolamine, anhydrous ethanol and glacial acetic acid is (4-6): (2.6-3.4): (42-56): (0.06-0.1).

4. An epoxy resin according to claim 2, characterized in that: In the step A2, the mass ratio of Schiff base monomer, p-toluenesulfonic acid, p-hydroxycinnamic acid and anhydrous ethanol is (4.2-5.6): (0.12-0.24): (3.8-5.0): (54-66).

5. An epoxy resin according to claim 2, characterized in that: In the step A3, the mass ratio of the modified monomer, methyl isobutyl ketone, tetrabutylammonium bromide, toluene, epichlorohydrin and the total amount of alkali solution is (5.4-6.6): (56-64): (0.04-0.06): (6-10): (2.4-3.0): (22-26), the alkali solution added dropwise for the first time is a sodium hydroxide aqueous solution with a mass fraction of 40-50%, and the alkali solution added dropwise for the second time is a sodium hydroxide aqueous solution with a mass fraction of 32-36%, and the masses of the alkali solutions added dropwise for the two times are the same.

6. An epoxy resin according to claim 1, characterized in that: The curing enhancer is prepared by the following steps: Step B1, add L-cysteine, trifluoromethanesulfonic acid and 3,3'-dithiodipropionic acid to anhydrous DMF, heat to 35-45°C, stir evenly, then heat to 72-84°C, continue stirring to react for 3.4-4.6h, rotary evaporate, wash, and dry to obtain a disulfide monomer; Step B2, add diethylenetriamine and disulfide monomer to anhydrous DMF, stir evenly, and drop a mixture of N,N-dicyclohexylcarbodiimide, 4-dimethylaminopyridine and anhydrous DMF while stirring. After the dropwise addition, heat to 72-78°C, stir to react for 3-5h, and after the reaction is completed, filter, wash and dry to obtain a curing enhancer.

7. An epoxy resin according to claim 6, characterized in that: In the step B1, the mass ratio of L-cysteine, trifluoromethanesulfonic acid, 3,3'-dithiodipropionic acid and anhydrous DMF is (3.6-4.4): (0.03-0.05): (2.1-2.7): (50-60).

8. An epoxy resin according to claim 6, characterized in that: In the step B2, the mass ratio of diethylenetriamine, disulfide monomer, anhydrous DMF and mixed solution a is (6-8): (20-26): (80-90): (30-40).

9. An epoxy resin according to claim 6, characterized in that: In the step B2, in the mixed solution a, the mass ratio of N,N-dicyclohexylcarbodiimide, 4-dimethylaminopyridine and anhydrous DMF is (5.6-7.2):(3.6-4.6):(23-27).

10. A method for preparing the epoxy resin according to any one of claims 1 to 9, characterized in that: The following steps are involved: The functionalized epoxy resin component, curing enhancer and photoinitiator are stirred evenly, heated to 42-46°C, irradiated with ultraviolet light for 14-18 minutes while stirring, and then a curing accelerator is added, heated to 54-62°C, and stirred for 32-46 minutes to obtain epoxy resin.

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