Modified curing agent component and preparation method thereof

Abstract

The invention discloses a modified curing agent component and a preparation method of the modified curing agent component. The modified curing agent component comprises a compound shown as a formula I, a compound shown as a formula II and a compound shown as a formula III. Also disclosed is a recoverable epoxy resin system comprising at least one epoxy resin component and the modified curing agent component. The curing temperature range of the recoverable epoxy resin system is 0-10 DEG C.

Description

Technical Field

[0001] This disclosure relates to a modified curing agent component and a method for preparing the modified curing agent component. Background Technology

[0002] Epoxy resins are a class of polymer materials widely used in various applications, such as high-performance materials, structural materials, aerospace composites, automotive composites, windmill composites, adhesives, paints, coatings, electrical and electronic applications, printed circuit boards (PCBs), molding, potting, and other specialty composite applications. Epoxy resins possess excellent mechanical and thermal properties, such as high strength, high chemical and solvent resistance, low shrinkage, excellent adhesion to various substrates, economy, and low toxicity.

[0003] To prepare epoxy resin compositions, a curing agent is needed to cure the epoxy resin (also known as the epoxy resin component). Curing is the process of transforming the liquid epoxy resin component into a solid, durable material. During curing, the epoxy resin component reacts with the curing agent to form a three-dimensional cross-linked thermosetting structure. Known curing agents include phenols, acid anhydrides, and amines. The curing agent typically affects the properties of the cured epoxy resin composition.

[0004] Therefore, there is a need for a curing agent for epoxy resins that can enable the cured epoxy resins to achieve uniform properties. Summary of the Invention

[0005] A modified curing agent component for epoxy resin systems is disclosed. The modified curing agent component comprises:

[0006] Compound of formula I is represented as:

[0007]

[0008] Each X is independently selected from:

[0009]

[0010] in:

[0011] n is 1-5; and

[0012] Each of R1, R2, R3, R4, R5 and R6 is selected from H, CH3, C2H5, or a combination thereof;

[0013] or

[0014]

[0015] in

[0016] n is 0-2;

[0017] m is 1-3;

[0018] R i Independently selected from methyl or ethyl; and

[0019] Each R ii The material is independently selected from ethylene, propylene, isopropylene, butene, isobutene, or combinations thereof;

[0020] Compound of formula II is represented as:

[0021]

[0022] Each X is independently selected from:

[0023]

[0024] in:

[0025] n is 1-5; and

[0026] Each of R1, R2, R3, R4, R5, and R6 is selected from H, CH3, C2H5, or a combination thereof; or

[0027]

[0028] in

[0029] n is 0-2;

[0030] m is 1-3;

[0031] R i Independently selected from methyl or ethyl; and

[0032] Each R ii Independently selected from ethylene, propylene, isopropylene, butene, isobutene, or combinations thereof; and compounds of formula III, represented as:

[0033]

[0034] Each X is independently selected from:

[0035]

[0036] in:

[0037] n is 1-5; and

[0038] Each of R1, R2, R3, R4, R5, and R6 is independently selected from H, CH3, C2H5, or a combination thereof; or

[0039]

[0040] in

[0041] n is 0-2;

[0042] m is 1-3;

[0043] R i Independently selected from methyl or ethyl; and

[0044] Each R ii It is independently selected from ethylene, propylene, isopropylene, butene, isobutene, or combinations thereof.

[0045] A method for preparing a modified curing agent component is also disclosed. The method includes: reacting a compound of formula IV with a compound selected from compounds of formula V, formula VI, and combinations thereof, wherein the compounds of formula IV, V, and VI are represented by the following structures:

[0046]

[0047] in

[0048] n is 0-1;

[0049] X is or OH;

[0050]

[0051]

[0052] in

[0053] n is between 1 and 5;

[0054] R1 to R6 are each independently selected from H, CH3 and C2H5;

[0055] as well as

[0056]

[0057] in

[0058] n is 0-2;

[0059] m is 1-3;

[0060] R i Independently selected from methyl or ethyl;

[0061] Each R ii The components are independently selected from ethylene, propylene, isopropylene, butene, isobutylene, or combinations thereof; to obtain the above-mentioned modified curing agent components.

[0062] A recyclable epoxy resin system is also disclosed, comprising at least one epoxy resin component and the aforementioned modified curing agent component. The curing temperature range of the recyclable epoxy resin system is 0℃-10℃. Detailed Implementation

[0063] To facilitate understanding of the principles of the invention, it will now be described with reference to embodiments and using specific language. However, it should be understood that this is not intended to limit the scope of the invention, and changes and further modifications to the disclosed methods, as well as further applications of the principles of the invention, are likely to occur to those skilled in the art.

[0064] Those skilled in the art will understand that the foregoing general description and the following detailed description are exemplary and illustrative of the invention and are not intended to limit the invention.

[0065] Throughout this specification, references to "an embodiment," "embodiment," or similar expressions indicate that a particular feature, structure, or characteristic described in connection with that embodiment is included in at least one embodiment of the invention. Therefore, the phrases "in one embodiment," "in an embodiment," and similar expressions appearing throughout this specification may (but not necessarily) refer to the same embodiment.

[0066] The glass transition temperature refers to the temperature range within which cured epoxy resin transitions from a rigid, glassy state to a rubbery state. The unit for glass transition temperature is °C (°C).

[0067] "Gel time" is defined as the time required for the mixture of epoxy resin and curing agent components to fully gel. The unit of gel time is minutes.

[0068] "Curing temperature" is defined as the temperature at which the epoxy resin component and the curing agent component cure to form a three-dimensional cross-linked thermosetting structure.

[0069] The Shore D hardness test is a method for determining the hardness of a material. The Shore D hardness rating is determined based on the depth to which an indenter can penetrate the material when a specified force is applied.

[0070] In the broadest sense, a modified curing agent component for epoxy resin systems is disclosed. This component enables the epoxy resin system to be recyclable. The disclosed modified curing agent component reacts rapidly with the epoxy resin component at both room temperature and low temperature. Therefore, the modified curing agent component enables the epoxy resin system to achieve the desired performance characteristics even at low temperatures. In one embodiment, the temperature range for curing the modified curing agent component with the epoxy resin component is 0-10°C.

[0071] In one aspect, a modified curing agent component for epoxy resin systems is disclosed. The modified curing agent component comprises:

[0072] Compound of formula I is represented as:

[0073]

[0074] Each X is independently selected from:

[0075]

[0076] Where n is 1-5; and

[0077] Each of R1, R2, R3, R4, R5 and R6 is selected from H, CH3, C2H5, or a combination thereof;

[0078] or

[0079]

[0080] in

[0081] n is 0-2;

[0082] m is 1-3;

[0083] R i Independently selected from methyl or ethyl;

[0084] Each R ii The material is independently selected from ethylene, propylene, isopropylene, butene, isobutene, or combinations thereof;

[0085] Compound of formula II is represented as:

[0086]

[0087] Each X is independently selected from:

[0088]

[0089] Where n is 1-5; and

[0090] Each of R1, R2, R3, R4, R5 and R6 is selected from H, CH3, C2H5, or a combination thereof;

[0091] or

[0092]

[0093] in

[0094] n is 0-2;

[0095] m is 1-3;

[0096] R iIndependently selected from methyl or ethyl; and

[0097] Each R ii Independently selected from ethylene, propylene, isopropylene, butene, isobutylene, or combinations thereof; and

[0098] Compounds of formula III are represented as follows:

[0099]

[0100] Each X is independently selected from:

[0101]

[0102] Where n is 1-5; and

[0103] Each of R1, R2, R3, R4, R5, and R6 is independently selected from H, CH3, C2H5, or a combination thereof; or

[0104]

[0105] in

[0106] n is 0-2;

[0107] m is 1-3;

[0108] R i Independently selected from methyl or ethyl; and

[0109] Each R ii It is independently selected from ethylene, propylene, isopropylene, butene, isobutene, or combinations thereof.

[0110] In one embodiment, the compound of formula I is selected from the compounds of formula IA, formula IB, formula IC, or formula ID; wherein the compounds of formula IA, formula IB, formula IC, and formula ID are respectively represented as:

[0111]

[0112] In some embodiments, the compound of formula (I) is the compound of formula IA.

[0113] In one embodiment, the compound of formula II is selected from compounds of formula IIA, IIB, IIC, or IID, wherein compounds of formula IIA, IIB, IIC, and IID are respectively represented as:

[0114]

[0115]

[0116] In some embodiments, the compound of formula II is a compound of formula IIA.

[0117] In one embodiment, the compound of formula III is selected from compounds of formula IIIA, IIIB, IIIC, IIID, IIIE, or IIIF; wherein compounds of formula IIIA, IIIB, IIIC, IIID, IIIE, and IIIF are respectively represented as follows:

[0118]

[0119]

[0120] In some embodiments, the compound of formula III is a compound of formula IIIA represented by the following formula:

[0121]

[0122] In some embodiments, the modified curing agent component includes compounds of formula IA, formula IIA, and formula IIIA, wherein the weight ratio of the three compounds is variable and depends on the molar ratio of the starting materials used. In some embodiments, the modified curing agent component includes compounds of formula IA, formula IIA, formula IIIA, formula IC, formula IIC, formula IIIC, and formula IIID, wherein the weight ratio of these compounds is variable and depends on the molar ratio of the starting materials used.

[0123] In one embodiment, the viscosity of the modified curing agent component at 25°C ranges from 200 to 80,000 cPs. In some embodiments, the viscosity of the modified curing agent component at 25°C ranges from 500 to 20,000 cPs.

[0124] In one embodiment, the amine value of the modified curing agent component ranges from 300 to 800 mg KOH / gm. In some embodiments, the amine value of the modified curing agent component ranges from 350 to 650 mg KOH / gm.

[0125] In one embodiment, the amine hydrogen equivalent weight (AHEW) of the modified curing agent component ranges from 50 to 250. In some embodiments, the AHEW of the modified curing agent component ranges from 65 to 180.

[0126] The modified curing agent components are mixtures of compounds of formula I, II, and III. When the modified curing agent components are used as curing agents to cure epoxy resin components, the epoxy resin thermosetting materials cured based on these modified curing agent components can undergo chemical decomposition under the required recycling conditions to form low molecular weight thermoplastic materials. The disclosed modified curing agent components also have improved performance properties, such as higher glass transition temperatures, mechanical strength, and faster achievement of Shore D hardness at low temperatures.

[0127] According to one embodiment, the modified curing agent component comprising compounds of formula I, II, and III includes acetal linkages, ketal linkages, and formalal linkages. When the modified curing agent component comprising compounds of formula I, II, and III is exposed to a high-temperature acidic solution, the acetal, ketal, and formalal linkages of the modified curing agent component are all degraded. In one embodiment, the degradation of the modified curing agent component occurs within a temperature range of 60 to 100°C. In one embodiment, the acid is selected from formic acid, acetic acid, and hydrochloric acid.

[0128] On the one hand, the compound of formula I in the modified curing agent component is a monomeric compound. The compound of formula II in the modified curing agent component is an oligomer. And the compound of formula III in the modified curing agent component is an oligomer, which is a fully transaminated product. On the other hand, the higher the content of the transaminated compound of formula III, the higher the proportion of functional amine molecules in the product mixture, which in turn leads to an increase in the viscosity of the modified curing agent component.

[0129] Preparation method of modified curing agent components

[0130] On the other hand, a method for preparing a modified curing agent component is disclosed.

[0131] Modified curing agent components, including compounds of formula I, II and III, are obtained by a transamination reaction of compound of formula IV with a compound selected from compounds of formula V, VI or combinations thereof.

[0132] Compounds of formula IV, V, and VI are represented by the following structures:

[0133]

[0134] Where X is or OH; and

[0135] n is 0-1;

[0136]

[0137] Where n is 1 to 5; and

[0138] R1 to R6 are each independently selected from H, CH3, or C2H5;

[0139] or

[0140]

[0141] Among them, R i Independently selected from methyl or ethyl;

[0142] Each R ii It is independently selected from ethylene, propylene, isopropylene, butene, isobutene, or combinations thereof.

[0143] Formula IV

[0144] In one embodiment, the compound of formula IV is selected from tris(dimethylaminomethyl)phenol, bis[(dimethylamino)methyl]phenol, ((dimethylamino)methyl)phenol, or combinations thereof. In another embodiment, the compound of formula IV is selected from 2,4-dihydroxymethylphenol, 2,6-dihydroxymethylphenol, or combinations thereof.

[0145] In some embodiments, the compound of formula IV is tris(dimethylaminomethyl)phenol.

[0146] Formula V

[0147] Compound V is selected from compounds of formula VA, formula VB, formula VC, formula VD, and formula VE; wherein compounds of formula VA, formula VB, formula VC, formula VD, and formula VE are represented by the following structures:

[0148]

[0149]

[0150] In some embodiments, compound V is compound VA and compound VB.

[0151] Style VI

[0152] Compound VI is selected from compounds of formula VIA, VIB, VIC, VID, and VIE; wherein compounds of formula VIA, VIB, VIC, VID, and VIE are represented by the following structures:

[0153]

[0154]

[0155] In some embodiments, compound VI is compound VIA.

[0156] In the disclosed method, the molar ratio of compounds of formula IV, V and VI, as well as the reaction temperature and reaction time, affect the degree of transamination, thereby affecting the proportion of compounds of formula I, II and III formed.

[0157] The reaction of compound IV with compound V or compound VI, or combinations thereof, results in the formation of dimethylamine (DMA) gas. During this reaction, dimethylamine is released as a byproduct. The extent of reaction (%T) between compound IV and compound V or compound VI, or combinations thereof, is determined by measuring the amount of DMA released during the reaction. The weight loss from the reaction after completion is considered the actual amount of DMA released. The degree of transamination is calculated using the following formula:

[0158]

[0159] The DMA formed during the reaction of compound IV with compound V or compound VI, or combinations thereof, is continuously removed from the reaction mixture and dissolved in a flask filled with water. The molar ratio of compounds IV, V, VI, and their combinations used in the reaction, as well as the reaction temperature and reaction time, affect the amount of dimethylamine released.

[0160] Formula IV and Formula V

[0161] In one embodiment, the method includes reacting a compound of formula IV with a compound of formula V to obtain a modified curing agent component comprising compounds of formula I, II, and III. In some embodiments, the compound of formula IV reacts with the compound of formula V at a molar ratio of 1:2 to 1:6. In some embodiments, the compound of formula IV reacts with the compound of formula V at a molar ratio of 1:2.5 to 1:4.

[0162] In the reaction of compound IV with compound V, if the molar concentration of compound V reacting is in excess compared to compound IV, the amount of compounds I and II formed is greater than the amount of compound III formed. In an exemplary embodiment, when 3 or more moles of compound V react with 1 mole of compound IV, the amount of compounds I and II formed is greater than the amount of compounds III formed. In another exemplary embodiment, when 2-3 moles of compound V react with 1 mole of compound IV, the amount of compound III formed is greater than the amount of compounds I and II formed.

[0163] The reaction of compound IV with compound V is carried out at high temperatures. In one embodiment, the reaction of compound IV with compound V is carried out in a temperature range of 100-160°C for 2-10 hours. In some embodiments, the reaction is continued at a temperature of 120-130°C for 4-6 hours. If the reaction of compound IV with compound V continues for more than 240 minutes, it results in an increased degree of transamination and an increase in viscosity.

[0164] The following are exemplary reaction schemes for obtaining the disclosed modified curing agent components:

[0165]

[0166] As shown in the reaction formula above, the reaction of compound IV with compound V results in the formation of a modified curing agent component comprising compounds I, II, and III. The phenolic OH group (phenolic hydroxyl group) in compound IV remains intact in the resulting modified curing agent component comprising compounds I, II, and III. The phenolic group catalyzes the reaction between the epoxy resin component and the modified curing agent component by activating the epoxy ring of the epoxy resin component. This reaction is highly effective even at lower temperatures.

[0167] Formula IV + Formula VI

[0168] In one embodiment, the compound of formula IV reacts with the compound of formula VI in a molar ratio of 1:2 to 1:6. In some embodiments, the compound of formula IV reacts with the compound of formula VI in a molar ratio of 1:2.5 to 1:4.

[0169] In the reaction of compound IV with compound VI, if the molar concentration of compound VI reacting is in excess compared to compound IV, the amounts of compounds I and II formed are greater than those of compound III. In an exemplary embodiment, when 3 moles of compound VIB react with 1 mole of compound IV, the amounts of compounds ID and IID formed are greater than those of compound IIIF. In another exemplary embodiment, when 2-3 moles of compound VI react with 1 mole of compound IV, the amount of compound IIID formed is greater than that of compounds ID and IID.

[0170] The reaction of compound IV with compound VI is carried out at high temperatures. In one embodiment, the reaction of compound IV with compound VI is carried out in a temperature range of 100-160°C for 2-10 hours. In some embodiments, the reaction is continued at a temperature of 125-140°C for 4-5 hours. If the reaction of compound IV with compound VI continues for more than 240 minutes, the degree of transamination increases with increasing viscosity.

[0171] The following provides an exemplary reaction scheme for obtaining the disclosed modified curing agent component by reacting a compound of formula IV with a compound of formula VI:

[0172]

[0173] In the above scheme, Formula IV is tris(dimethylaminomethyl)phenol.

[0174] Formula IV+V+VI

[0175] In one embodiment, the compound of formula IV reacts with a mixture of compounds of formula V and formula VI in a molar ratio of 1:2-2.8:0.2-1. In some embodiments, the compound of formula IV reacts with a mixture of compounds of formula V and formula VI in a molar ratio of 1:2.5:0.5.

[0176] The reaction of compound IV with a mixture of compounds V and VI is carried out at high temperatures. In one embodiment, the reaction of compound IV with a mixture of compounds V and VI is carried out in a reaction temperature range of 100-160°C for 2-10 hours. In some embodiments, the reaction is continued at a temperature of 120-130°C for 5-6 hours. If the reaction of compound IV with compound VI continues for more than 240 minutes, it results in an increased degree of transamination and an increase in viscosity.

[0177] The following provides an exemplary reaction scheme in which a mixture of Formula IV and Formula V and Formula VI compounds are reacted to obtain a modified curing agent component comprising Formula I, Formula II and Formula III compounds.

[0178]

[0179]

[0180] In the above scheme, Formula IV is tris(dimethylaminomethyl)phenol.

[0181] In one embodiment, the modified curing agent component is also prepared by reacting a compound of formula IV with a compound of formula V, and a compound selected from aliphatic amines, aromatic amines, alicyclic amines and heterocyclic amines.

[0182] The obtained modified curing agent components comprising compounds of formula I, II, and III are viscous liquids. In some embodiments, the viscous modified curing agent components may be further processed according to conventional methods or techniques known in the art. In one embodiment, the viscous curing agent components may be mixed or diluted with one or more commercially available curing agents, accelerators, or solvents.

[0183] Recyclable epoxy resin systems

[0184] On the other hand, this disclosure also relates to an epoxy resin system comprising at least one epoxy resin component and the above-described modified curing agent component.

[0185] In one embodiment, the epoxy resin system is recyclable. After curing with the modified curing agent component, a cured epoxy resin thermosetting material is formed; unlike conventional epoxy resin systems prepared using epoxy resin components and conventional curing agents, the cured epoxy resin thermosetting material prepared in this application can be chemically decomposed. The recyclable epoxy resin system can be softened in an acidic solution at temperatures from 60°C to 100°C. In some embodiments, the acidic solution is an aqueous solution of acetic acid. Because the methyl acetal, acetal, and ketal bonds of the modified curing agent component are acid-insecure, the recyclable epoxy resin system can dissolve under these conditions. These bonds break in the acidic solution at elevated temperatures, thereby making the epoxy resin system recyclable.

[0186] Compared to conventional curing agents without added accelerators, the disclosed modified curing agent components, including phenolic groups, enable recyclable epoxy resin systems to dry faster.

[0187] The modified curing agent component enables the epoxy resin component to cure rapidly at room temperature and relatively low ambient temperatures. In one embodiment, the modified curing agent component cures the epoxy resin component faster in a temperature range of 0-10°C compared to conventional curing agents. In some embodiments, the modified curing agent component cures the epoxy resin component at a temperature of about 5°C and accelerates the establishment of Shore D hardness.

[0188] In some embodiments, when the epoxy resin component needs to be cured at a lower temperature, an epoxy resin component that is liquid at the operating temperature is selected. In some embodiments, the epoxy resin component is a mixture of bisphenol A diglycidyl ether and bisphenol F diglycidyl ether. In another embodiment, the epoxy resin component is selected from: bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, hydrogenated bisphenol A diglycidyl ether, phenolic varnish diglycidyl ether, p-aminophenol triglycidyl ether, and methylene diphenylamine tetraglycidyl ether. In one embodiment, the epoxy resin system includes a diluent that keeps the epoxy resin system liquid even at lower temperatures. In one embodiment, the diluent is selected from: phenolic diglycidyl ether, cresol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, and C12-C14 alcohol monoglycidyl ether.

[0189] According to one embodiment, the modified curing agent component and the epoxy resin component are added based on their epoxy equivalent weight (EEW) and average epoxy resin weight (AHEW). In a recyclable epoxy resin system, the weight of the curing agent component for every 100g of epoxy resin component can be calculated using the following formula:

[0190] Weight of curing agent component = AHEW * 100 / epoxy equivalent weight

[0191] According to one embodiment, the viscosity range of the epoxy resin component is 50-30000 cps. According to one embodiment, the content of by-products and impurities in the epoxy resin component is less than 10000 ppm.

[0192] According to one embodiment, the recyclable epoxy resin system may further include additives. In addition to the modified curing agent component and the epoxy resin component, the additives may also be added as a separate component. Additives include, but are not limited to, fibers, toughening agents, softeners, pigments, fillers, defoamers, wetting agents, or combinations thereof.

[0193] According to one embodiment, the gel time of the recyclable epoxy resin system ranges from 30 to 1000 minutes. In some embodiments, the gel time of the recyclable epoxy resin system ranges from 50 to 500 minutes. According to one embodiment, the glass transition temperature of the recyclable epoxy resin system is from 70 to 160°C. In some embodiments, the glass transition temperature of the recyclable epoxy resin system is from 85 to 130°C.

[0194] According to one embodiment, the tensile strength of the recyclable epoxy resin system ranges from 50 to 150 MPa. In some embodiments, the tensile strength of the recyclable epoxy resin system ranges from 60 to 100 MPa. According to one embodiment, the elongation at break of the recyclable epoxy resin system ranges from 1% to 15%. In some embodiments, the elongation at break of the recyclable epoxy resin system ranges from 1% to 10%. According to one embodiment, the lap shear strength of the recyclable epoxy resin system ranges from 1 to 10 MPa. In some embodiments, the lap shear strength of the recyclable epoxy resin system ranges from 2 to 5 MPa.

[0195] The following examples illustrate certain embodiments and aspects of the invention, but should not be construed as limiting the scope of the invention. Unless otherwise stated, all parts and percentages are by weight.

[0196] Example 1: Preparation of modified curing agent components according to embodiments of the present disclosure.

[0197] 150 g (0.565 mmol) of tris(dimethylaminomethyl)phenol and 275 g (1.697 mmol) of compound VA were added to a four-necked reaction flask equipped with a temperature controller, heating mantle, water condenser, top stirrer, and nitrogen inlet to form a reaction mixture. The reaction mixture was heated to 110–125 °C, and DMA purged from the water condenser was transferred to a water vessel. The reaction mixture was then kept under constant stirring at 120 °C for 400 min. After 400 min of reaction, 60 g of DMA was collected in the water vessel, corresponding to a transamination rate of 79%. 365 g of a yellow viscous liquid containing the modified curing agent was obtained.

[0198] Product characteristics description: Table 1 provides the characteristics of the modified curing agent components obtained above.

[0199] Table 1: Characteristics of Modified Curing Agent Components

[0200] No. Parameter Property 1. Amine value 560 mg KOH / g 2. Viscosity at 25 °C cP 2780 3. Amine hydrogen equivalent (AHEW) 68

[0201] Example 2: Preparation of modified curing agent components according to embodiments of the present disclosure.

[0202] Except for reflux of the reaction mixture under constant stirring for 360 minutes, all other steps followed the experimental procedure of Example 1. 54.5 g of DMA was collected in a water container, corresponding to a transamination rate of 71.5%. 370.5 g of a yellow, viscous liquid containing the modified curing agent component was obtained.

[0203] Product characteristics description: Table 2 provides the characteristics of the modified curing agent components obtained above.

[0204] Table 2: Characteristics of Modified Curing Agent Components

[0205] No. Parameter Property 1. Amine value 567 mg KOH / g 2. Viscosity at 25 °C 1980 cP 3. AHEW 71

[0206] Example 3: Preparation of modified curing agent components according to embodiments of the present disclosure.

[0207] Except for reflux of the reaction mixture under constant stirring for 440 minutes, all other steps followed the experimental procedure of Example 1. 73 g of DMA was collected in a water container, corresponding to a transamination rate of 96%. 352 g of a yellow, viscous liquid containing the modified curing agent component was obtained.

[0208] Product characteristics description: Table 3 provides the characteristics of the modified curing agent components obtained above.

[0209] Table 3: Characteristics of Modified Curing Agent Components

[0210] No. Parameter Property 1. Amine value 561 mg KOH / g 2. Viscosity at 25 °C 5369 cP 3. AHEW 68

[0211] Observations: It was observed that the amount of DMA generated increased with prolonged reaction time, indicating an increase in the degree of transamination. With increasing transamination, the proportions of compounds of formula I and II were greater than that of compound III.

[0212] Example 4: Preparation of modified curing agent components according to embodiments of the present disclosure.

[0213] 150 g (0.565 mmol) of tris(dimethylaminomethyl)phenol and 275 g (1.697 mmol) of compound (VA) were added to a four-necked reaction flask equipped with a temperature controller, heating mantle, water condenser, top stirrer, and nitrogen inlet to form a reaction mixture. The reaction mixture was heated at 110–125 °C, and DMA discharged from the water condenser was drained into a water container. Subsequently, the reaction mixture was stirred at a constant temperature of 120 °C for 330 minutes. After 330 minutes of reaction, 68 g of DMA was collected in the water container, corresponding to a transamination rate of 89.5%. 329 g of a yellow viscous liquid containing the modified curing agent was obtained.

[0214] Product characteristics description: Table 4 provides the characteristics of the modified curing agent components obtained above.

[0215] Table 4: Characteristics of Modified Curing Agent Components

[0216] No. Parameter Property 1. Amine value 542 mg KOH / g 2. Viscosity at 25 °C 9320 cP 3. AHEW 71.6

[0217] Example 5: Preparation of modified curing agent components according to embodiments of the present disclosure.

[0218] Except for reflux of the reaction mixture under constant stirring for 440 minutes, all other steps followed the experimental procedure of Example 4. 56.5 g of DMA was collected in a water container, corresponding to a transamination rate of 74%. 310 g of a yellow, viscous liquid containing the modified curing agent component was obtained.

[0219] Product characteristics description: Table 5 provides the characteristics of the modified curing agent components obtained above.

[0220] Table 5: Characteristics of Modified Curing Agent Components

[0221] No. Parameter Property 1. Amine value 572 mg KOH / g 2. Viscosity at 25 °C 3280 cP 3. AHEW 70

[0222] Observations: It was observed that the amount of DMA generated increased with prolonged reaction time, indicating an increase in the degree of transamination. With increasing transamination, the proportions of compounds of formula I and II were greater than that of compound III.

[0223] Example 6: Preparation of modified curing agent components according to embodiments of the present disclosure.

[0224] 100 g (0.377 mmol) of tris(dimethylaminomethyl)phenol and 190 g (0.989 mmol) of compound (VB) were added to a four-necked reaction flask equipped with a temperature controller, heating mantle, water condenser, top stirrer, and nitrogen inlet to form a reaction mixture. The reaction mixture was heated at 130–140 °C, and DMA discharged from the water condenser was drained into a water container. Subsequently, the reaction mixture was stirred at a constant temperature of 135 °C for 330 minutes. After 330 minutes of reaction, 40 g of DMA was collected in the water container, corresponding to a transamination rate of 82%. 250 g of a yellow viscous liquid containing the modified curing agent was obtained.

[0225] Product characteristics description: Table 6 provides the characteristics of the modified curing agent components obtained above.

[0226] Table 6: Characteristics of Modified Curing Agent Components

[0227]

[0228]

[0229] Example 7: Preparation of modified curing agent components according to embodiments of the present disclosure.

[0230] 100 g (0.377 mmol) of tris(dimethylaminomethyl)phenol and 215 g (1.119 mmol) of compound (VB) were added to a four-necked reaction flask equipped with a temperature controller, heating mantle, water condenser, top stirrer, and nitrogen inlet to form a reaction mixture. The reaction mixture was heated at 130–140 °C, and DMA discharged from the water condenser was drained into a water container. Subsequently, the reaction mixture was stirred at a constant temperature of 135 °C for 420 min. After 420 min of reaction, 47 g of DMA was collected in the water container, corresponding to a transamination rate of 92%. 268 g of a yellow viscous liquid containing the modified curing agent was obtained.

[0231] Product characteristics description: Table 7 provides the characteristics of the modified curing agent components obtained above.

[0232] Table 7: Characteristics of Modified Curing Agent Components

[0233] No. Parameter Property 1. Amine value 536 mg KOH / g 2. Viscosity at 25 °C 15580 cP 3. AHEW 77

[0234] Example 8: Preparation of modified curing agent components according to embodiments of the present disclosure.

[0235] 100 g (0.377 mmol) of tris(dimethylaminomethyl)phenol and 213.6 g (1.318 mmol) of compound (VA) were added to a four-necked reaction flask equipped with a temperature controller, heating mantle, water condenser, top stirrer, and nitrogen inlet to form a reaction mixture. The reaction mixture was heated at 110–125 °C, and DMA discharged from the water condenser was drained into a water container. The reaction mixture was stirred at a constant temperature of 125 °C for 270 min. After 270 min of reaction, 45 g of DMA was collected in the water container, corresponding to a transamination rate of 88%. 169 g of a yellow viscous liquid containing the modified curing agent was obtained.

[0236] Product characteristics description: Table 8 provides the characteristics of the modified curing agent components obtained above.

[0237] Table 8: Characteristics of Modified Curing Agent Components

[0238] No. Parameter Property 1. Amine value mg KOH / g 511 2. Viscosity at 25 °C cP 2144 3. AHEW 64

[0239] Example 9: Preparation of modified curing agent components according to embodiments of the present disclosure.

[0240] 100 g (0.377 mmol) of tris(dimethylaminomethyl)phenol and 244 g (1.51 mmol) of compound VA were added to a four-necked reaction flask equipped with a temperature controller, heating mantle, water condenser, top stirrer, and nitrogen inlet to form a reaction mixture. The reaction mixture was heated at 110–125 °C, and DMA discharged from the water condenser was drained into a water container. Subsequently, the reaction mixture was stirred at a constant temperature of 120 °C for 360 minutes. After 360 minutes of reaction, 48 g of DMA was collected in the water container, corresponding to a transamination rate of 94%. 296 g of a yellow viscous liquid containing the modified curing agent was obtained.

[0241] Product characteristics description: Table 9 provides the characteristics of the modified curing agent components obtained above.

[0242] Table 9: Characteristics of Modified Curing Agent Components

[0243] No. Parameter Property 1. Amine value mg KOH / g 539 2. Viscosity at 25 °C cP 1588 3. AHEW 60

[0244] Example 10: Preparation of modified curing agent components according to embodiments of the present disclosure.

[0245] 100 g (0.377 mmol) of tris(dimethylaminomethyl)phenol and 153 g (0.944 mmol) of compound (VA) were added to a four-necked reaction flask equipped with a temperature controller, heating mantle, water condenser, top stirrer, and nitrogen inlet to form a reaction mixture. The reaction mixture was heated at 110–125 °C, and DMA discharged from the water condenser was drained into a water container. Subsequently, the reaction mixture was stirred at a constant temperature of 120 °C for 270 min. After 270 min of reaction, 38 g of DMA was collected in the water container, corresponding to a transamination rate of 74.5%. 217 g of a yellow viscous liquid containing the modified curing agent was obtained.

[0246] Product characteristics description: Table 10 provides the characteristics of the modified curing agent components obtained above.

[0247] Table 10: Characteristics of Modified Curing Agent Components

[0248] No. Parameter Property 1. Amine value mg KOH / g 531 2. Viscosity at 25 °C cP 3860 3. AHEW 60

[0249] Example 11: Preparation of modified curing agent components according to embodiments of the present disclosure.

[0250] 75 g (0.285 mmol) of tris(dimethylaminomethyl)phenol and 91.6 g (0.565 mmol) of compound VA were added to a four-necked reaction flask equipped with a temperature controller, heating mantle, water condenser, top stirrer, and nitrogen inlet to form a reaction mixture. The reaction mixture was heated at 110–125 °C, and the DMA discharged from the water condenser was drained into a water container. Subsequently, the reaction mixture was kept under constant stirring at 120 °C for 50 minutes. During the 50 minutes of reaction, gelation occurred in the reaction mixture. This is because the low molar ratio of compound VA results in a high degree of polymerization, leading to crosslinking / gelation.

[0251] Example 12: Preparation of modified curing agent components according to embodiments of the present disclosure.

[0252] 100 g (0.377 mmol) of tris(dimethylaminomethyl)phenol and 248.7 g (1.14 mmol) of compound VD were added to a four-necked reaction flask equipped with a temperature controller, heating mantle, water condenser, top stirrer, and nitrogen inlet to form a reaction mixture. The reaction mixture was stirred at a constant temperature of 130–140 °C for 360 min. DMA discharged from the water condenser was drained into a water container. After 360 min of reaction, 30 g of DMA was collected in the water container, representing a transamination rate of 58.5%. 318.5 g of a yellow viscous liquid containing the modified curing agent was obtained.

[0253] Product characteristics description: Table 12 provides the characteristics of the modified curing agent components obtained above.

[0254] Table 12: Characteristics of Modified Curing Agent Components

[0255] No. Parameter Property 1. Amine value mg KOH / g 470 2. Viscosity at 25 °C cP 303 3. AHEW 82

[0256] Example 13: Preparation of modified curing agent components according to embodiments of the present disclosure.

[0257] 100 g (0.377 mmol) of tris(dimethylaminomethyl)phenol and 153 g (0.944 mmol) of compound (VD) were added to a four-necked reaction flask equipped with a temperature controller, heating mantle, water condenser, top stirrer, and nitrogen inlet to form a reaction mixture. The reaction mixture was heated at 140–150 °C for 360 min. DMA discharged from the water condenser was drained into a water container. After 360 min of reaction, 39 g of DMA was collected in the water container, corresponding to a transamination rate of 75%. 309 g of a yellow viscous liquid containing the modified curing agent was obtained.

[0258] Product characteristics description: Table 13 provides the characteristics of the modified curing agent components obtained above.

[0259] Table 13: Characteristics of Modified Curing Agent Components

[0260] No. Parameter Property 1. Amine value mg KOH / g 417 2. Viscosity at 25 °C cP 1330 3. AHEW 84.5

[0261] Example 14: Preparation of modified curing agent components according to embodiments of the present disclosure.

[0262] 100 g (0.377 mmol) of tris(dimethylaminomethyl)phenol and 249 g (1.141 mmol) of compound VE were added to a four-necked reaction flask equipped with a temperature controller, heating mantle, water condenser, top stirrer, and nitrogen inlet to form a reaction mixture. The reaction mixture was heated at 140–150 °C for 390 min. DMA discharged from the water condenser was drained into a water container. After 390 min of reaction, 35 g of DMA was collected in the water container, representing a transamination rate of 68.5%. 314 g of a yellow viscous liquid containing the modified curing agent was obtained.

[0263] Product characteristics description: Table 14 provides the characteristics of the modified curing agent components obtained above.

[0264] Table 14: Characteristics of Modified Curing Agent Components

[0265] No. Parameter Property 1. Amine value mg KOH / g 458 2. Viscosity at 25 °C cP 2213 3. AHEW 83.75

[0266] Example 15: Preparation of modified curing agent components according to embodiments of the present disclosure.

[0267] 100 g (0.377 mmol) of tris(dimethylaminomethyl)phenol, 152.6 g (0.9419 mmol) of compound VA, and 57.9 g (0.1892 mmol) of compound VIB were added to a four-necked reaction flask equipped with a temperature controller, heating mantle, water condenser, top stirrer, and nitrogen inlet to form a reaction mixture. The reaction mixture was heated at 120–130 °C and stirred constantly for 360 min. DMA discharged from the water condenser was drained into a water container. After 360 min of reaction, 38.5 g of DMA was collected in the water container, corresponding to a transamination rate of 75.5%. 274 g of a yellow viscous liquid containing the modified curing agent was obtained.

[0268] Product characteristics description: Table 15 provides the characteristics of the modified curing agent components obtained above.

[0269] Table 15: Characteristics of Modified Curing Agent Components

[0270] No. Parameter Property 1. Amine value mg KOH / g 531 2. Viscosity at 25 °C cP 1910 3. AHEW 68

[0271] Example 16: Preparation of modified curing agent components according to embodiments of the present disclosure.

[0272] 100 g (0.377 mmol) of tris(dimethylaminomethyl)phenol, 152.6 g (0.9419 mmol) of compound VA, and 49.7 g (0.1624 mmol) of compound VIC were added to a four-necked reaction flask equipped with a temperature controller, heating mantle, water condenser, top stirrer, and nitrogen inlet to form a reaction mixture. The reaction mixture was heated at 120–130 °C for 360 min. DMA discharged from the water condenser was drained into a water container. After 360 min of reaction, 42 g of DMA was collected in the water container, corresponding to a transamination rate of 82.5%. 274 g of a yellow viscous liquid containing the modified curing agent was obtained.

[0273] Product characteristics description: Table 16 provides the characteristics of the modified curing agent components obtained above.

[0274] Table 16: Characteristics of Modified Curing Agent Components

[0275] No. Parameter Property 1. Amine value mg KOH / g 561 2. Viscosity at 25 °C cP 3320 3. AHEW 70

[0276] Example 17: Preparation of a recyclable epoxy resin system according to embodiments of the present disclosure.

[0277] Recyclable epoxy resin systems were prepared using the modified curing agent components and epoxy resin components described above. Table 17 below provides a list of the various recyclable epoxy resin systems prepared.

[0278] Table 17: Formulation of Epoxy Resin Systems

[0279]

[0280] Tests conducted: Various processing characteristics tests were performed on the epoxy resin system obtained above.

[0281] Gel time:

[0282] Gel time at 25 °C:

[0283] The gel times of the prepared recyclable epoxy resin systems 1a, 2a, and 3a at 25°C were determined using a Gelnorm GT-SP gel timer. The total batch size for the experiments was 100 grams. The stamper was immersed in the cups containing the recyclable epoxy resin systems 1a, 2a, and 3a, and the instrument was started. After the timer was started, the timer reading was recorded as the gel time after the epoxy resin systems had completely gelled. Table 18 provides the gel times of the recyclable epoxy resin systems 1a, 2a, and 3a, as well as conventional epoxy resin system A, at 25°C.

[0284] Table 18: Gel time of recyclable epoxy resin systems 1a, 2a and 3a and conventional epoxy resin system A at 25°C

[0285]

[0286]

[0287] Observation results: The results show that at 25°C, the gel times of recyclable epoxy resin systems 1a, 2a and 3a are not significantly different from those of conventional epoxy resin system A, indicating that the reactivity of the modified curing agent components is similar to that of the conventional curing agent.

[0288] Gel time at 5-7 °C

[0289] The gel times of the recyclable epoxy resin systems 1b, 2b, and 3b prepared in Table 17, as well as conventional epoxy resin system A, were determined at 5–7 °C using a Gelnorm GT-SP gel timer. Table 19 provides the gel times of the recyclable epoxy resin systems 1b, 2b, and 3b, as well as conventional epoxy resin system A, at 7 °C.

[0290] Table 19: Gel Time of Recyclable Epoxy Resin Systems 1b, 2b, and 3b, and Conventional Epoxy Resin System A at 5-7°C

[0291]

[0292] Observation results: The results show that at low temperatures of 5-7℃, the recyclable epoxy resin systems 1b, 2b, and 3b exhibit faster gel times compared to conventional epoxy resin system A. This indicates that the modified curing agent components are more reactive than conventional curing agents at low temperatures.

[0293] Processing characteristics: Recyclable epoxy resin systems 1a, 2a and 3a were cured at 80°C for 4 hours in a closed system, and their glass transition temperature, tensile strength, elongation at break and lap shear strength were then tested.

[0294] Glass transition temperature (Tg):

[0295] Tg values ​​were determined using Differential Scanning Calorimetry (DSC) according to ASTM D3418. The results are provided in Table 20 below.

[0296] Tensile strength and elongation (%):

[0297] The prepared recyclable epoxy resin systems 1a, 2a, and 3a, along with conventional epoxy resin system A, were cast into dumbbell-shaped molds to prepare dumbbell-shaped samples; the effective length of the dumbbell-shaped mold was 50 mm, and the width was 10 mm. The prepared samples were cured at 80°C for 4 hours to achieve complete curing. Tensile strength and elongation at % were tested according to ASTM D638 standard. The results are provided in Table 20 below.

[0298] Overlap shear strength:

[0299] The prepared recyclable epoxy resin systems 1a, 2a, and 3a, along with conventional epoxy resin system A, were used as adhesives on 25×50mm aluminum plates. First, the prepared epoxy resin systems were applied to a 25×25mm area on one side of the aluminum plate. A second aluminum plate was then bonded together according to standard to prepare test samples according to ASTM D1002. The samples were cured at 80°C for 4 hours to achieve complete curing. The lap shear strength of the prepared samples was tested according to ASTM D1002. The results are provided in Table 20 below.

[0300] Table 20 provides the processing characteristics of the prepared recyclable epoxy resin systems 1a, 2a, 3a and conventional epoxy resin system A.

[0301] Table 20: Processing Characteristics

[0302]

[0303] Observations: Compared with conventional epoxy resin system A, the glass transition temperatures (Tg) of recyclable epoxy resin systems 1a, 2a, and 3a are increased. The increase in Tg is mainly due to the higher functionality of the modified curing agent components, leading to dense cross-linking, which restricts molecular motion and thus results in a higher Tg.

[0304] For the recyclable epoxy resin systems 1a, 2a, and 3a, the tensile strength also showed a gradual increase. This is because the modified curing agent component of this application has multifunctional properties, thereby forming a more cross-linked or denser three-dimensional network structure.

[0305] Example 18: Preparation of a recyclable epoxy resin system according to an embodiment of the present disclosure.

[0306] Recyclable epoxy resin system 1c and conventional epoxy resin system B were prepared by using the curing agents and epoxy resin components specified in Table 21 below.

[0307] Table 21: Formulation of Epoxy Resin Systems

[0308] No. Epoxy resin system Curing agent Epoxy resin component 1. Recyclable epoxy resin system 1c Modified curing agent component of example 7 Bisphenol A diglycidyl ether 2. Conventional epoxy resin system B Compound of formula VB Bisphenol A diglycidyl ether Bisphenol A diglycidyl ether

[0309] The modified curing agent component obtained in Example 7 was cured with bisphenol A diglycidyl ether in a closed system at 80°C for 4 hours to form a recyclable epoxy resin system 1c.

[0310] Conventional epoxy resin system B is prepared by curing bisphenol A diglycidyl ether and compound VB in a closed system at 80°C for 4 hours.

[0311] The gel time, glass transition temperature, tensile strength, elongation at break, and lap shear strength of the prepared recyclable epoxy resin system 1c and conventional epoxy resin system B were measured. Table 22 below provides the performance characteristics of recyclable epoxy resin system 1c and conventional epoxy resin system B.

[0312] Table 22: Processing Characteristics

[0313]

[0314]

[0315] Results: The results showed that the gel time of the recyclable epoxy resin system 1c was significantly shorter than that of the conventional epoxy resin system B, indicating faster reactivity even at room temperature (25°C). The tensile strength and lap shear strength of the recyclable epoxy resin system 1c were also improved compared to the conventional epoxy resin system B, indicating faster and more complete curing of the epoxy resin system, resulting in better strength properties.

[0316] Example 19: Preparation of coating composition.

[0317] Recyclable epoxy resin systems 1b, 2b, and 3b were prepared by curing the epoxy resin components and curing agents specified in Table 17 at 5-8°C. Coatings 1, 2, and 3 were prepared using the prepared recyclable epoxy resin systems 1b, 2b, and 3b.

[0318] Conventional epoxy resin system C was prepared by curing bisphenol A diglycidyl ether and compound VA. Conventional coatings were then prepared using conventional epoxy resin system C.

[0319] To evaluate drying performance, a 400 μm thick film was coated onto a glass plate using recyclable epoxy resin systems 1b, 2b, and 3b, as well as a conventional epoxy resin system C. The film was then cast according to ASTM D 2240 for Shore D hardness measurement and cured at 5–8°C.

[0320] The performance characteristics of the coating are listed in Table 23.

[0321] Table 23: Performance Characteristics of Coatings

[0322]

[0323] *Testing was not possible because the sample was not fully cured.

[0324] - Complete curing / drying

[0325] Observations: Shore D hardness measurements showed that coatings prepared using recyclable epoxy resin systems 1b, 2b, and 3b dried faster at lower temperatures, as clearly demonstrated in the film drying results. This faster drying is due to the faster reactivity of the modified curing agent components compared to conventional curing agents.

[0326] Example 21: Recycling of epoxy thermosetting resins.

[0327] Cured samples (dumbbell-shaped samples) prepared using the recyclable epoxy resin system of this disclosure were kept in a 25% aqueous acetic acid solution at 100°C for 1 hour. Within 30 minutes of immersion in the acidic solution, the samples began to soften and decompose. Within 1 hour, the samples were completely decomposed and recovered as thermoplastic polymers after purification.

[0328] Industrial applicability

[0329] The modified curing agent components disclosed herein can be used to prepare epoxy resin systems with reprocessable and recyclable properties. Furthermore, these modified curing agent components enable faster curing, rapid strength development, and higher crosslinking density at low temperatures.

[0330] The modified curing agent component and the epoxy resin component cure rapidly at both room temperature and low temperature to form a recyclable epoxy resin system. The low-temperature curing of the modified curing agent component and the epoxy resin component minimizes the internal stress of the recyclable epoxy resin system, thereby improving dimensional stability and performance.

[0331] Recyclable epoxy resin systems obtained by using modified curing agent components possess excellent processing and performance characteristics, making them suitable for a wide range of applications, including high-tech fields such as microelectronics, transportation, aerospace, and composite materials. Furthermore, these recyclable epoxy resin systems have suitable properties for standard thermosetting composite material preparation techniques, such as wet layup, fiber winding, vacuum infusion, compression molding, and resin transfer molding. Composite materials prepared from these recyclable epoxy resin systems exhibit excellent mechanical properties, making them applicable to various composite material applications. Moreover, composite materials obtained using recyclable epoxy resin systems can degrade under specific conditions, enabling the separation and recycling of reinforcing fibers, epoxy resin components, and modified curing agent components. Since the epoxy resin matrix of the prepared composite materials originates from reprocessable modified curing agent components, these composite materials can be precisely recycled.

Claims

1. A modified curing agent component for use in epoxy resin systems, said modified curing agent component comprising: Compound of formula I is represented as: Each X is independently selected from: in: n is 1-5; and Each of R1, R2, R3, R4, R5, and R6 is selected from H, CH3, C2H5, or a combination thereof; or in n is 0-2; m is 1-3; Ri is independently selected from methyl or ethyl; and Each Rii is independently selected from ethylene, propylene, isopropylene, butene, isobutylene, or combinations thereof; - Formula II compounds are represented as: Each X is independently selected from: in: n is 1-5; and Each of R1, R2, R3, R4, R5 and R6 is independently selected from H, CH3, C2H5, or a combination thereof; or in n is 0-2; m is 1-3; Ri is independently selected from methyl or ethyl; and Each Rii is independently selected from ethylene, propylene, isopropylene, butene, isobutylene, or combinations thereof; and Compounds of formula III are represented as follows: Each X is independently selected from: in: n is 1-5; and Each of R1, R2, R3, R4, R5 and R6 is independently selected from H, CH3, C2H5, or a combination thereof; or in n is 0-2; m is 1-3; R i Independently selected from methyl or ethyl; and Each R ii It is independently selected from ethylene, propylene, isopropylene, butene, isobutene, or combinations thereof.

2. The modified curing agent component according to claim 1, characterized in that, The compound of formula I is selected from compounds of formula IA, formula IB, formula IC, and formula ID, and compounds of formula IA, formula IB, formula IC, and formula ID are represented by the following structural formulas:

3. The modified curing agent component according to claim 1, characterized in that, The compound of formula II is selected from compounds of formula IIA, IIB, IIC, and IID, and the compounds of formula IIA, IIB, IIC, and IID are represented by the following structural formulas:

4. The modified curing agent component according to claim 1, characterized in that, The compound of formula III is selected from compounds of formula IIIA, IIIB, IIIC, IIID, IIIE, and IIIF, and the compounds of formula IIIA, IIIB, IIIC, IIID, IIIE, and IIIF are represented by the following structural formulas:

5. A method for preparing a modified curing agent component, the method comprising: The compound of formula IV is reacted with a compound selected from compounds of formula V, formula VI, and combinations thereof, wherein the compounds of formula IV, V, and VI are represented by the following structures: in n is 0-1; X is or OH; in n is between 1 and 5; R1 to R6 are each independently selected from H, CH3 and C2H5; as well as in n is 0-2; m is 1-3; R i Independently selected from methyl or ethyl; Each R ii The modified curing agent component is independently selected from ethylene, propylene, isopropylene, butene, isobutylene, or combinations thereof; said modified curing agent component comprises: Compound of formula I is represented as: Each X is independently selected from: in: n is 1-5; and Each of R1, R2, R3, R4, R5 and R6 is selected from H, CH3, C2H5, or a combination thereof; or in n is 0-2; m is 1-3; Ri is independently selected from methyl or ethyl; Each Rii is independently selected from ethylene, propylene, isopropylene, butene, isobutylene, or a combination thereof; Compound of formula II is represented as: Each X is independently selected from: in: n is 1-5; and Each of R1, R2, R3, R4, R5 and R6 is selected from H, CH3, C2H5, or a combination thereof; or in: n is 0-2; m is 1-3; Ri is independently selected from methyl or ethyl; and Each Rii is independently selected from ethylene, propylene, isopropylene, butene, isobutylene, or a combination thereof; Compounds of formula III are represented as follows: Each X is independently selected from: in n is 1-5; and Each of R1, R2, R3, R4, R5 and R6 is independently selected from H, CH3, C2H5, or a combination thereof; or in n is 0-2; m is 1-3; Ri is independently selected from methyl or ethyl; and Each Rii is independently selected from ethylene, propylene, isopropylene, butene, isobutylene, or a combination thereof.

6. The method according to claim 5, characterized in that, The compound of formula IV reacts with the compound of formula V in a molar ratio of 1:2 to 1:

6.

7. The method according to claim 5, characterized in that, The compound of formula IV reacts with the compound of formula V in a molar ratio of 1:2.5 to 1:

4.

8. The method according to claim 5, characterized in that, The compound of formula IV reacts with a mixture of the compounds of formula V and formula VI in a molar ratio of 1:2-2.8:0.2-1.

9. The method according to claim 5, characterized in that, The compound of formula IV is reacted with a compound selected from the compound of formula V, the compound of formula VI, and combinations thereof in a temperature range of 100-160°C for a reaction time of 2-10 hours.

10. The method according to claim 5, characterized in that, The compound of Formula IV is selected from tris(dimethylaminomethyl)phenol, bis[(dimethylamino)methyl]phenol, ((dimethylamino)methyl)phenol, or combinations thereof.

11. The method according to claim 5, characterized in that, The compound of formula IV is selected from 2,4-dihydroxymethylphenol, 2,6-dihydroxymethylphenol, or a combination thereof.

12. The method according to claim 5, characterized in that, The compound of formula V is selected from compounds of formula VA, formula VB, formula VC, formula VD, and formula VE, and the compounds of formula VA, formula VB, formula VC, formula VD, and formula VE are respectively represented as follows:

13. The method according to claim 5, characterized in that, The compound of formula VI is selected from compounds of formula VIA, formula VIB, formula VIC, formula VID, and formula VIE, wherein compounds of formula VIA, formula VIB, formula VIC, formula VID, and formula VIE are respectively represented as follows: as well as 14. A recyclable epoxy resin system, comprising at least one epoxy resin component and a modified curing agent component, said modified curing agent component comprising: Compound of formula I is represented as: Each X is independently selected from: in: n is 1-5; and Each of R1, R2, R3, R4, R5 and R6 is selected from H, CH3, C2H5 or a combination thereof; or in: n is 0-2; m is 1-3; Ri is independently selected from methyl or ethyl; Each Rii is independently selected from ethylene, propylene, isopropylene, butene, isobutylene, or a combination thereof; Compound of formula II is represented as: Each X is independently selected from: in: n is 1-5; and Each of R1, R2, R3, R4, R5 and R6 is independently selected from H, CH3, C2H5, or a combination thereof; or in n is 0-2; m is 1-3; Ri is independently selected from methyl or ethyl; and Each Rii is independently selected from ethylene, propylene, isopropylene, butene, isobutylene, or combinations thereof; and Compounds of formula III are represented as follows: Each X is independently selected from: Where n is 1-5; and Each of R1, R2, R3, R4, R5 and R6 is independently selected from H, CH3, C2H5, or a combination thereof; or in n is 0-2; m is 1-3; Ri is independently selected from methyl or ethyl; and Each Rii is independently selected from ethylene, propylene, isopropylene, butene, isobutylene, or a combination thereof; The curing temperature range of the recyclable epoxy resin system is 0℃-10℃.

15. The recyclable epoxy resin system according to claim 14, characterized in that, The epoxy resin component is selected from: bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, hydrogenated bisphenol A diglycidyl ether, phenolic varnish glycidyl ether, p-aminophenol triglycidyl ether, methylene diphenylamine tetraglycidyl ether, or combinations thereof.

16. The recyclable epoxy resin system according to claim 14, characterized in that, It also includes a diluent selected from: phenol glycidyl ether, cresol glycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, and C12-C14 alcohol monoglycidyl ether.

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