Toughening agent for epoxy resin, epoxy resin toughening blend and preparation method of epoxy resin toughening blend

Abstract

The invention relates to the technical field of epoxy resin, in particular to a toughening agent for epoxy resin, an epoxy resin toughening blend and a preparation method of the epoxy resin toughening blend. Wherein the raw materials of the toughening agent comprise poly (butylene adipate) glycol, hexahydrophthalic anhydride and epoxy chloropropane, and the obtained linear polyester containing terminal epoxy and saturated cyclohexane dicarboxylate specific groups has better performance in the aspects of toughening, dilution, compatibility and demolding of an epoxy resin matrix, especially a bisphenol A epoxy resin matrix; the material can be directly mixed with an epoxy resin matrix and a curing agent; the elongation at break and the comprehensive toughness of an epoxy resin toughened blend using the toughening agent are greatly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of epoxy resin, in particular to a toughening agent for epoxy resin, an epoxy resin toughening blend and a preparation method thereof. BACKGROUND

[0002] Epoxy resin is a general term for polymers containing two or more epoxy groups in the molecule. Due to the excellent reactivity of the epoxy group, compounds containing active hydrogen or acid anhydride can cause ring opening, and at a certain temperature, cross-linking forms a network structure, which is a thermosetting material. The cured epoxy resin has the advantages of strong adhesion, low shrinkage, excellent mechanical strength, good insulation performance, excellent acid and alkali resistance, etc., and is one of the most widely used thermosetting materials today.

[0003] However, the highly cross-linked structure provides good strength while resulting in poor toughness of the epoxy resin, which is prone to brittle fracture when subjected to external force or thermal stress.

[0004] The current mainstream toughening method of epoxy resin can be divided into several categories: (1) rigid inorganic filler (particles) toughening: the unmodified epoxy resin matrix in brittle resin phase carries out sharp crack tip stress concentration, so the damage proceeds rapidly, after adding rigid particles, if the rigid particles and the resin are well bonded, the tensile stress can effectively inhibit the crack propagation when the rigid particles are plastically deformed, and at the same time, part of the energy is absorbed, thereby playing a toughening effect. (2) Rubber-based thermoplastic elastomer toughening: the rubber reacts with the active groups (epoxy group, hydroxyl group, etc.) in the epoxy resin to form a block through its active end groups (such as carboxyl, hydroxyl, amino, etc.). In the resin curing process, these rubber segments are separated from the matrix to form a two-phase structure in physics. In this rubber-based toughened epoxy resin, the main role of the rubber phase is to induce the energy consumption process of the matrix, and the energy consumed by the stretching and tearing of the rubber itself in the fracture process generally occupies a secondary position. (3) Forming a semi-interpenetrating network structure with thermoplastic resin for toughening: the use amount of thermoplastic resin in this toughening system is large, and the thermoplastic resin is continuously penetrated in the thermosetting resin network. Due to the presence of thermoplastic resin, the toughness of epoxy resin cured material can be improved, and the water absorption can be reduced, and the presence of epoxy resin can maintain its chemical resistance, dimensional stability, etc. (4) Changing the chemical structure of the cross-linked network for toughening: for some high cross-linking density epoxy resin matrix cross-linked network, the brittleness of such materials is particularly large, if modified by rubber-based elastomer containing active end groups, due to the small yield deformation potential of the matrix, the toughness improvement is not large, and the glass transition temperature and modulus of the toughened material are significantly reduced. If some active but heat-resistant "flexible segments" are added to the above system to increase the activity of the network molecules, a more ideal toughening effect can be obtained (such as CTBN / epoxy resin system modified by adding bisphenol A). (5) Controlling the unevenness of the cross-linked network state of the molecular chain to improve the toughness of the epoxy resin: this is a kind of epoxy resin synthesized by using "in-situ toughening" technology. This method is realized by two-stage reaction, so that the cross-linked network of the epoxy resin with bimodal distribution of molecular weight is formed after cross-linking. The toughness of the resin prepared by this method can reach 2~10 times of that of the conventional resin. Its toughening mechanism is to form a micro non-uniform continuous structure due to the unevenness of the cross-linked network of the epoxy resin cured product, so as to realize the toughening. Because this structure is fundamentally conducive to the plastic deformation of the material, it has good toughness.

[0005] The patent document with publication number CN104262615A discloses such a polyether type hyperbranched polymer with phenolic hydroxyl end groups, which is modified by epoxidation of the end groups and used together with epoxy resin and curing agent, the impact strength and tensile strength are improved. Among them, the impact strength is the embodiment of dynamic toughness, and the tensile strength represents the material's ability to resist deformation. This material focuses on dynamic toughness and load-bearing capacity, but it is still insufficient in improving the quasi-static toughness of the material, especially the elongation at break.

[0006] The patent document with publication number CN115873225A discloses a polyester epoxy diluent, epoxy adhesive and its preparation method. The polyester polyol is modified by epoxidation and used as a diluent for epoxy resin, but a toughening agent and other raw materials need to be added to obtain the effect of improving toughness. SUMMARY

[0007] The present application solves the above problems and provides a toughening agent for epoxy resin, an epoxy resin toughening blend and a preparation method thereof. The toughening agent has good performance in improving the toughness, compatibility, dilution, demolding and other aspects of the epoxy resin. The epoxy resin toughening blend using the toughening agent not only has greatly improved elongation at break, but also does not need to use diluents, compatibilizers, mold release agents and other additives. It is environmentally friendly and low cost, and avoids the adverse effects of these additives, such as diluents volatilizing into pores during curing and compatibilizers migrating and decomposing, on the mechanical properties and service life of the epoxy resin.

[0008] The technical solution of the present application to solve the problem is as follows: in the first aspect, a toughening agent for epoxy resin is provided, which has the following structure: .

[0009] In this application, the inventors have unexpectedly found that this linear polyester containing end epoxy and specific groups of saturated cyclohexane dicarboxylate has good performance in toughening, diluting, compatibilizing and demolding of epoxy resin matrix, especially bisphenol A epoxy resin matrix, and can be directly mixed with epoxy resin matrix and curing agent. The inventors speculate that this may be because, compared with the hyperbranched polyether in the prior art, the linear polyester is more likely to absorb energy through chain segment motion, thereby improving the elongation at break of the material. Compared with the polyester in the prior art, the chair conformation flipping ability of the saturated cyclohexane in cyclohexane dicarboxylate endows the molecular chain with dynamic flexibility, which dissipates energy through conformational change during stretching, thereby improving the elongation at break of the material; the ester groups at both ends of cyclohexane improve the polarity of the structure, which can more effectively disperse stress.

[0010] In the second aspect, the present application also aims to provide a preparation method of the toughening agent for epoxy resin, which comprises the following steps: S1. reacting polybutylene adipate diol, hexahydrophthalic anhydride, triethylamine in a solvent at 50-100℃ for 12-72h, removing the solvent, acidifying to obtain the product; wherein the product has the following structure: .

[0011] S2. reacting the product with epichlorohydrin in a catalyst at 50-100℃ for 6-24h to obtain the toughening agent.

[0012] The toughening agent has the following structure: .

[0013] In step S1, as preferred in the present application, the solvent is acetonitrile. After the reaction, the solvent can be removed by distillation.

[0014] As preferred in the present application, the molecular weight of the polybutylene adipate diol is 600-2000g / mol.

[0015] As preferred in the present application, the molar ratio of the polybutylene adipate diol, hexahydrophthalic anhydride, triethylamine is 1:(10-20):(10-20). Exemplarily, when the molar fraction of the polybutylene adipate diol is 1 part, the molar fraction of the hexahydrophthalic anhydride can be 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, 20 parts, and the molar fraction of the triethylamine can be 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, 20 parts. Further preferably, the molar ratio of the polybutylene adipate diol, hexahydrophthalic anhydride, triethylamine is 1:15:15.

[0016] The reaction temperature is 50-100℃, exemplarily, it can be 50℃, 55℃, 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, 95℃, 100℃; further preferably, the reaction temperature is 90℃.

[0017] The reaction time is 12-72h, exemplarily, it can be 12h, 24h, 36h, 48h, 60h, 72h; further preferably, the reaction time is 48h.

[0018] As preferred in the present application, the acidification refers to acidification under concentrated hydrochloric acid condition.

[0019] As preferred in the present application, after acidification, a purification step is further included: dissolving the acidification product in dichloromethane, dropping into cold methanol for purification and filtering.

[0020] In step S2, as a preferred embodiment of the present application, the catalyst is selected to be bis(triphenylphosphine)ammonium chloride. Preferably, the mass ratio of the toughening agent and the catalyst is (90-100):1, and for example, can be 90:1, 91:1, 92:1, 93:1, 94:1, 95:1, 96:1, 97:1, 98:1, 99:1, or 100:1.

[0021] As a preferred embodiment of the present application, the ratio of the amount of the toughening agent and the epichlorohydrin is 1g:(1-5)mL, and for example, can be 1g:1mL, 1g:1.5mL, 1g:2mL, 1g:2.5mL, 1g:3mL, 1g:3.5mL, 1g:4mL, 1g:4.5mL, or 1g:5mL.

[0022] The reaction temperature is 50-100°C, and for example, can be 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, or 100°C; further preferably, the reaction temperature is 90°C.

[0023] The reaction time is 6-24h, and for example, can be 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h, or 24h; further preferably, the reaction time is 12h.

[0024] As a preferred embodiment of the present application, the excess epichlorohydrin is removed by rotary evaporation after the reaction.

[0025] As a preferred embodiment of the present application, the purification step is further included, in which the product is dissolved in dichloromethane, dropped into cold methanol for purification and filtration.

[0026] Through the above steps, the yield can reach more than 85%.

[0027] In a third aspect, the present application has another object to provide an epoxy resin toughening blend, which comprises an epoxy resin matrix, a curing agent, and the above toughening agent.

[0028] As a preferred embodiment of the present application, the epoxy resin toughening blend is composed of an epoxy resin matrix, a curing agent, and the above toughening agent, without the need to add other additives.

[0029] As a preferred embodiment of the present application, the epoxy resin matrix is bisphenol A epoxy resin.

[0030] As a preferred embodiment of the present application, the curing agent is phthalic anhydride. The toughening agent of the present application is particularly suitable for bisphenol A epoxy resin and phthalic anhydride curing agent.

[0031] As a preferred embodiment of the present application, the epoxy resin toughening blend is composed of bisphenol A epoxy resin, phthalic anhydride, and the above toughening agent.

[0032] Based on this specific toughening agent, the amount of toughening agent is limited. As a preferred embodiment of the present application, the amount of toughening agent is 10-100 wt% of the amount of epoxy resin matrix, for example, it can be 10 wt%, 20 wt%, 30 wt%, 40 wt%, 50 wt%, 60 wt%, 70 wt%, 80 wt%, 90 wt%, 100 wt%. The toughening agent in this range can improve the elongation at break of the blend. With the increase of the amount of toughening agent, the elongation at break is improved, while the tensile strength is reduced. If the amount of toughening agent is too high and exceeds the limited range, the tensile strength may be too low to cause the blend to yield prematurely, deform excessively or even fail to bear the required load in practical applications, so that the advantage of high ductility cannot be fully utilized, and even directly lead to functional failure.

[0033] From the perspective of improving the elongation at break, increasing the amount of toughening agent can improve the elongation at break. When the amount of toughening agent is more than 40 wt% of the amount of epoxy resin matrix, the elongation at break of the blend is greatly increased. Therefore, preferably, the amount of toughening agent is 40-100 wt% of the amount of epoxy resin matrix.

[0034] The essence of toughness is the total energy absorbed, which is related to both tensile strength and elongation at break, and can be approximately regarded as a product relationship. In the limited range of 10-100 wt%, the improvement degree of elongation at break is greater than the reduction degree of tensile strength, and compared with the epoxy resin without the toughening agent, the blend still shows better toughness. From the perspective of improving toughness, preferably, the amount of toughening agent is 50-90 wt% of the amount of epoxy resin matrix, further preferably 60-80 wt%, and further preferably 70-80 wt%. Not only is the elongation at break high, but also the comprehensive toughness is best.

[0035] The amount of curing agent is limited by the amount of epoxy resin matrix and toughening agent. As a preferred embodiment of the present application, the curing agent includes a first part and a second part. The amount of the first part is 15-25 wt% of the amount of epoxy resin matrix, for example, it can be 15 wt%, 16 wt%, 17 wt%, 18 wt%, 19 wt%, 20 wt%, 21 wt%, 22 wt%, 23 wt%, 24 wt%, 25 wt%, and preferably 20 wt%. The amount of the second part is 5-15 wt% of the amount of toughening agent, for example, it can be 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15 wt%, and preferably 10 wt%.

[0036] In a fourth aspect, the present application also aims to provide a method for preparing the epoxy resin toughening blend as described above, comprising the following steps: (1) mixing the epoxy resin matrix, the curing agent and the toughening agent, and then vacuumizing and pre-curing at 140-160°C; (2) feeding the pre-cured product into a mold, and curing at 140-160°C.

[0037] In step (1), the temperature for vacuumizing and pre-curing can be exemplarily 140°C, 145°C, 150°C, 155°C, 160°C, and is preferably 140°C.

[0038] Preferably, the vacuumizing and pre-curing is performed for 5-15 minutes, which can be exemplarily 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, 10 minutes, 11 minutes, 12 minutes, 13 minutes, 14 minutes, 15 minutes, and is preferably 10 minutes.

[0039] In step (2), the curing temperature can be exemplarily 140°C, 145°C, 150°C, 155°C, 160°C, and is preferably 140°C.

[0040] Preferably, the curing is performed for 6-12 hours, which can be exemplarily 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, and is preferably 6 hours.

[0041] The present application has the following beneficial effects: 1. The present application provides a toughening agent for epoxy resin, an epoxy resin toughening blend and a method for preparing the same. The toughening agent has good performance in improving the toughness, compatibility, dilution and demolding of epoxy resin, especially bisphenol A epoxy resin. The epoxy resin toughening blend using the toughening agent has greatly improved elongation at break, and does not need to use diluents, compatibilizers, demolding agents and other additives. The blend is environmentally friendly and low-cost, and avoids the adverse effects of these additives, such as the volatilization of diluents into pores during the curing process and the migration and decomposition of compatibilizers, on the mechanical properties and service life of the epoxy resin.

[0042] 2. In some embodiments, the amount ratio of the toughening agent to the epoxy resin matrix is controlled so that the epoxy resin toughening blend also has good performance in terms of comprehensive toughness. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 is a tensile curve of the product prepared in Example 4; Figure 2 is a tensile curve of the product prepared in Example 6; Figure 3 is a tensile curve of the product prepared in Example 11; Figure 4 is a tensile curve of the product prepared in the blank example; Figure 5 is a comparison chart of effects of the products prepared in the blank example and examples 3-12. DETAILED DESCRIPTION

[0044] The following is a specific embodiment of the present application, and the technical solutions of the present application are further described in conjunction with the drawings, but the present application is not limited to these embodiments. Example 1

[0045] A toughening agent for epoxy resin is prepared by the following steps: S1. Put 0.05 mol of polybutylene adipate glycol with a molecular weight of 2000 g / mol, 1 mol of triethylamine, 1 mol of hexahydrophthalic anhydride, and 800 ml of acetonitrile into a 2000 ml round-bottom flask, and react at 90°C for 36 hours. After the reaction, add 100 ml of concentrated hydrochloric acid for acidification, remove most of the acetonitrile and hydrochloric acid by rotary evaporation, add water and stir thoroughly, and filter the water. Dissolve the obtained product in dichloromethane, drop it into cold methanol for purification and filtration, and obtain 230.23 g of polyester filter cake.

[0046] S2. Transfer the obtained polyester to a 1000 ml round-bottom flask, add 400 ml of epichlorohydrin and 2.4 g of ppncl, and react at 90°C for 12 hours. Remove the epichlorohydrin by rotary evaporation, dissolve the obtained product in 50 ml of dichloromethane, drop it into cold methanol for purification, and filter to obtain a polyester-type epoxy resin filter cake. Dry the filter cake in a vacuum oven at 35°C under vacuum, and the yield is 85.06%. Example 2

[0047] A toughening agent for epoxy resin is prepared by the following steps: S1. Put 0.05 mol of polybutylene adipate glycol with a molecular weight of 2000 g / mol, 1 mol of triethylamine, 1 mol of hexahydrophthalic anhydride, and 800 ml of acetonitrile into a 2000 ml round-bottom flask, and react at 90°C for 36 hours. After the reaction, add 100 ml of concentrated hydrochloric acid for acidification, remove most of the acetonitrile and hydrochloric acid by rotary evaporation, add water and stir thoroughly, and filter the water. Dissolve the obtained product in dichloromethane, drop it into cold methanol for purification and filtration, and obtain 230.23 g of polyester filter cake.

[0048] S2. Transfer the obtained polyester to a 1000 ml round-bottom flask, add 400 ml of epichlorohydrin and 2.4 g of ppncl, and react at 90°C for 12 hours. Remove the epichlorohydrin by rotary evaporation, dissolve the obtained product in 50 ml of dichloromethane, drop it into cold methanol for purification, and filter to obtain a polyester-type epoxy resin filter cake. Dry the filter cake in a vacuum oven at 35°C under vacuum, and the yield is 85.06%. Examples 3-12

[0049] An epoxy resin toughening blend, consisting of E-12 epoxy resin, phthalic anhydride, the toughening agent prepared in Example 1, is prepared by the following steps: (1) The phthalic anhydride, the toughening agent, the E-12 epoxy resin are ground into powder, and the three are weighed in a certain proportion and placed in a sample bottle, and shaken well to mix evenly. Place in a vacuum oven at 140°C and pre-cure for 10 min.

[0050] (2) Then pour the pre-cured sample in the sample bottle into a detachable polytetrafluoroethylene mold, and cure at 140°C for 6h to obtain the product.

[0051] In Examples 3-12, only the amounts of E-12 epoxy resin, phthalic anhydride, and toughening agent are different, as shown in Table 1 below.

[0052] Table 1.

[0053] In Example 4, the tensile curve of the product prepared with 20wt% of the toughening agent based on the amount of E-12 epoxy resin is shown in Figure 1 , which shows that the strain (elongation at break) reaches 12.3% and the tensile stress reaches 75.32MPa.

[0054] In Example 6, the tensile curve of the product prepared with 40wt% of the toughening agent based on the amount of E-12 epoxy resin is shown in Figure 2 , which shows that the strain reaches 20.5% and the tensile stress reaches 67.57MPa.

[0055] In Example 11, the tensile curve of the product prepared with 90wt% of the toughening agent based on the amount of E-12 epoxy resin is shown in Figure 3 , which shows that the strain reaches 142.55% and the tensile stress reaches 16.21MPa.

[0056] Compared with Example 6, the elongation at break of Example 11 increases significantly, with an increase rate of 6 times, and the tensile stress only decreases by 76%, and Example 11 has better overall toughness than Example 6. Blank Example The blank example is basically the same as Examples 3-12, except that it does not contain the toughening agent.

[0057] (1) 5g of E-12 epoxy resin and 1g of phthalic anhydride are ground into powder, and the two are mixed evenly in a sample bottle by shaking well, and placed in a vacuum oven at 140°C and pre-cured for 10 min.

[0058] (2) Then the pre-cured sample in the sample bottle is poured into a detachable polytetrafluoroethylene mold and cured at 140°C for 6 hours to obtain the product.

[0059] The tensile curve of the product prepared with E-12 epoxy resin and toughening agent at 0 wt% is shown in the blank example. Figure 4 As shown, the strain is only 8.9%, and the tensile stress is 83.2 MPa.

[0060] Comparing the blank example with the elongation at break and tensile stress of Examples 4, 6, and 11 above, it can be seen that in this application, regardless of the amount of toughening agent used within the specified range, the elongation at break of the material can be effectively improved; at the same time, the rate of increase in elongation at break is greater than the rate of decrease in tensile stress, which indicates that the material of this application exhibits better overall toughness.

[0061] The comparison diagrams of the effects of the blank example and the products prepared in Examples 3-12 are shown below. Figure 5 As shown, when the amount of toughening agent reaches more than 40 wt% of E-12 epoxy resin, the elongation at break increases significantly. In the range of 60-80 wt% of toughening agent and E-12 epoxy resin, the slope of the increase in elongation at break is significantly greater than the slope of the decrease in tensile stress, indicating that the material in this range exhibits the best overall toughness. Comparative Example 1

[0062] Comparative Example 1 is basically the same as Example 4, except that the toughening agent is different. In the preparation of the toughening agent, hexahydrophthalic anhydride is replaced with phthalic anhydride.

[0063] The toughening agent is prepared through the following steps: S1. Add 0.05 mol of polybutylene adipate diol with a molecular weight of 2000 g / mol, 1 mol of triethylamine, 1 mol of phthalic anhydride poly(1,3-cyclohexanedicarboxylic acid) butylene glycol ester 800 ml of acetonitrile was added to a 2000 ml round-bottom flask and reacted at 90 °C for 36 h. After the reaction, 100 ml of concentrated hydrochloric acid was added for acidification. Most of the acetonitrile and hydrochloric acid were removed by rotary evaporation. Water was added and stirred thoroughly, and the mixture was filtered. The resulting product was dissolved in dichloromethane, purified by dropwise addition to cold methanol, and then filtered.

[0064] S2. Transfer the obtained polyester to a 1000ml round-bottom flask, add 400ml epichlorohydrin and 2.4g ppncl, react at 90℃ for 12h, remove epichlorohydrin by rotary evaporation, dissolve the obtained product in 50ml dichloromethane, purify by dropwise addition to cold methanol, and filter to obtain polyester-type epoxy resin filter cake, which is then dried in a vacuum oven at 35℃.

[0065] The blend was prepared by the following steps: (1) 1.1 g of phthalic anhydride, 1 g of the obtained toughening agent, and 5 g of E-12 epoxy resin were ground into powder, mixed uniformly by shaking in a sample bottle, and pre-cured in a vacuum oven at 140°C for 10 min.

[0066] (2) The pre-cured sample in the sample bottle was then poured into a detachable polytetrafluoroethylene mold, and cured at 140°C for 6 h to obtain a product. Comparative Example 2

[0067] This comparative example 1 is basically the same as Example 4, except that the toughening agent is different, and the polybutylene adipate diol is replaced by poly(1,3 cyclohexanedicarboxylic acid) butylene ester in the preparation process of the toughening agent.

[0068] The toughening agent was prepared by the following steps: S1. 0.05 mol of polyethylene glycol with a molecular weight of 2000 g / mol, 1 mol of succinic acid, 1 mol of triethylamine, 1 mol of hexahydrophthalic anhydride, and 800 ml of acetonitrile were added to a 2000 ml round-bottom flask and reacted at 90°C for 36 h. After the reaction, 100 ml of concentrated hydrochloric acid was added for acidification, most of the acetonitrile and hydrochloric acid were removed by rotary evaporation, water was added for stirring, and the water was filtered. ​ S2. The obtained polyester was transferred to a 1000 ml round-bottom flask, 400 ml of epichlorohydrin and 2.4 g of ppncl were added, and the reaction was carried out at 90°C for 12 h. The epichlorohydrin was removed by rotary evaporation, the obtained product was dissolved in 50 ml of dichloromethane, purified by dropping into cold methanol, and filtered to obtain a polyester-type epoxy resin filter cake, which was dried in a vacuum oven at 35°C under vacuum.

[0069] The blend was prepared by the following steps:

[0070] (1) 1.1 g of phthalic anhydride, 1 g of the obtained toughening agent, and 5 g of E-12 epoxy resin were ground into powder, mixed uniformly by shaking in a sample bottle, and pre-cured in a vacuum oven at 140°C for 10 min. (2) The pre-cured sample in the sample bottle was then poured into a detachable polytetrafluoroethylene mold, and cured at 140°C for 6 h to obtain a product.

[0071] The elongation at break and tensile stress of the products prepared in Comparative Examples 1-2 were compared with those of the blank and Example 4, and the results are shown in Table 2.

[0072] Table 2.

[0073]

[0074] ​As shown in Table 2, the toughening agent of the present application is used by the synergistic use of specific main chain and functional groups to achieve the technical effect of improving the elongation at break and comprehensive toughness of the material.

[0075] The specific embodiments described herein are merely illustrative of the principles of this application. Numerous modifications or adaptations will be readily apparent to those skilled in the art of the present application without departing from the spirit or scope of the present application as defined in the appended claims.

Claims

1. A toughening agent for epoxy resin, characterized in that: The toughening agent has the following structure: 。 2. A method for preparing an epoxy resin toughening agent as described in claim 1, comprising the following steps: S1. Polybutylene adipate diol, hexahydrophthalic anhydride, and triethylamine are reacted in a solvent at 50-100°C for 12-72 h, then the solvent is removed and the mixture is acidified to obtain the product. S2. The product is reacted with epichlorohydrin at 50-100°C for 6-24 hours with a catalyst to obtain the toughening agent.

3. The method for preparing an epoxy resin toughening agent according to claim 1, characterized in that: The molar ratio of polybutylene adipate diol, hexahydrophthalic anhydride, and triethylamine is 1:(10~20):(10~20).

4. An epoxy resin toughened blend, characterized in that: It includes an epoxy resin matrix, a curing agent, and a toughening agent as described in claim 1.

5. The epoxy resin toughened blend according to claim 4, characterized in that: It is composed of the epoxy resin matrix, the curing agent, and the toughening agent.

6. An epoxy resin toughened blend according to claim 4 or 5, characterized in that: The epoxy resin matrix is ​​bisphenol A epoxy resin, and the curing agent is phthalic anhydride.

7. The epoxy resin toughened blend according to claim 4, characterized in that: The amount of toughening agent used is 10 to 100 wt% of the amount of epoxy resin matrix used.

8. The epoxy resin toughened blend according to claim 7, characterized in that: The amount of toughening agent used is 60-80 wt% of the amount of epoxy resin matrix used.

9. The epoxy resin toughened blend according to claim 4, characterized in that: The curing agent comprises a first part, which is 15-25 wt% of the amount of the epoxy resin matrix, and a second part, which is 5-15 wt% of the amount of the toughening agent.

10. A method for preparing an epoxy resin toughened blend as described in any one of claims 4 to 9, characterized in that: Includes the following steps: After mixing the epoxy resin matrix, curing agent, and toughening agent, vacuum is applied and pre-cured at 140~160℃. The pre-cured product is fed into a mold and cured at 140~160℃.

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