A cyclodextrin modified epoxy resin toughening agent, an epoxy adhesive and a preparation method thereof

Abstract

The application provides a cyclodextrin modified epoxy resin toughening agent, an epoxy adhesive and a preparation method thereof. A chemical structural formula of the cyclodextrin modified epoxy resin toughening agent is shown in the following formula 1: the cyclodextrin modified epoxy resin toughening agent has excellent mechanical strength and temperature resistance, low production cost, is easy to synthesize, and is non-toxic and environmentally friendly.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of composite materials, and particularly relates to a cyclodextrin modified epoxy resin toughening agent, an epoxy adhesive and a preparation method thereof. BACKGROUND

[0002] Epoxy resin has excellent mechanical strength, adhesion, thermal stability and chemical stability, and is widely used in the fields of adhesives, coatings and composites. In the field of automobile manufacturing, epoxy structural adhesive, as a new type of vehicle body connection process, has the advantages of light weight, high mechanical strength, stress concentration reduction and good sealing, and is gradually replacing welding technology. However, the brittleness of epoxy resin is relatively large, and the impact resistance is poor. In order to make the epoxy structural adhesive meet the actual production demand, a toughening agent needs to be added.

[0003] The current main toughening ideas of epoxy resin are as follows: (1) using a second phase such as elastomer, thermoplastic resin or rigid particle to form an "island structure" with the epoxy resin body to toughen; (2) using thermoplastic resin to form a molecular interpenetrating network (IPN) to toughen; (3) adding flexible segments to improve the network molecular activity to toughen. Commonly used toughening agents include carboxyl-terminated liquid nitrile rubber (CTBN), blocked isocyanate, polyether ether ketone (PEEK), and core-shell nanoparticles. However, most of the above toughening agents have complex synthesis, high production cost, and certain toxicity of the intermediates produced, and cannot improve the gelation performance of epoxy resin, which limits the application of the above toughening agents in high-performance epoxy adhesives.

[0004] For example, the Chinese patent document with publication number CN117683155A discloses an epoxy star-shaped polybutadiene toughening agent and its preparation method and application. Star-shaped polybutadiene liquid rubber is synthesized by anionic polymerization method, with a single-arm Mn of 3000-8000, arm number of 7-10, coupling efficiency of 75%-95%, and vinyl content of 10%-90%. The obtained star-shaped polybutadiene liquid rubber is then epoxidized by organic acid and hydrogen peroxide to obtain an epoxidized star-shaped polybutadiene liquid rubber with an epoxidation degree of 45%-60%. The epoxidized star-shaped polybutadiene liquid rubber, as a toughening agent, can be uniformly dispersed in the epoxy resin matrix, co-cured, reduce the crosslinking density, and significantly improve the impact strength of the epoxy resin, while basically not losing the mechanical properties. However, this epoxy star-shaped polybutadiene toughening agent does not have excellent temperature resistance. The Chinese patent document with publication number CN116102712A discloses an epoxy resin toughening agent and its preparation method and application. The epoxy resin toughening agent is prepared by using a block liquid crystal with an end group epoxy, which can increase the impact strength of the epoxy resin by 5-8 kJ / m2, and significantly optimize the comprehensive mechanical properties of the epoxy resin product. Although the liquid crystal material improves the toughness and impact strength of the epoxy resin, the improvement effect is limited, and the high temperature resistance is not significantly improved.

[0005] Therefore, it is necessary to provide a preparation method of an epoxy resin toughener with excellent mechanical strength and temperature resistance, low production cost, easy synthesis, and no toxicity and environmental protection. SUMMARY

[0006] The technical problem solved by the present application is to provide a cyclodextrin modified epoxy resin toughener, an epoxy adhesive and a preparation method thereof, aiming to overcome the problems of existing tougheners, such as complex synthesis, high production cost, certain toxicity of intermediates produced, and inability to improve the gelation performance of epoxy resin, effectively improve the toughness and heat resistance of epoxy resin by introducing a slip ring structure into the epoxy resin polymer network through the host-guest interaction between cyclodextrin and bisphenol A diglycidyl ether, and provide a novel preparation method of an environmentally friendly, efficient and economical epoxy resin toughener.

[0007] To solve the above problems, a first aspect of the present application provides a cyclodextrin modified epoxy resin toughener, whose chemical structural formula is:

[0008]

[0009] A second aspect of the present application provides a preparation method of the cyclodextrin modified epoxy resin toughener as described above, comprising the following steps:

[0010] The bisphenol A diglycidyl ether is mixed with β-cyclodextrin, NaOH is added for reaction, and the cyclodextrin modified epoxy resin toughener is obtained.

[0011] Preferably, the reaction temperature is 25-40℃, the molar ratio of the β-cyclodextrin to the bisphenol A diglycidyl ether is 1:5-20; after the reaction is completed, the pH is adjusted to 6-7 with an acid, then washed at least twice, and dried to obtain the cyclodextrin modified epoxy resin toughener.

[0012] A third aspect of the present application provides a one-component epoxy adhesive, comprising the following components in mass fraction:

[0013] 25-50 parts of bisphenol A type epoxy resin, 10-20 parts of the cyclodextrin modified epoxy resin as described above, 15-25 parts of polyurethane modified epoxy resin, 10-20 parts of liquid butyronitrile rubber modified epoxy resin, 15-25 parts of inorganic filler, 1-5 parts of thixotropic agent, and 13-20 parts of latent curing agent.

[0014] Preferably, the bisphenol A type epoxy resin is one or a mixture of several of E51, E54, E44 and E20.

[0015] Preferably, the inorganic filler is one or a combination of several of nano calcium carbonate, heavy calcium, silica powder, mica powder, talc powder, and kaolin.

[0016] Preferably, the latent curing agent is one or a combination of dicyandiamide, imidazole derivative or polyether amine.

[0017] Preferably, the thixotropic agent is one or a combination of fumed silica, hydrogenated castor oil or bentonite.

[0018] The fourth aspect of the present application provides a preparation method of the one-component epoxy adhesive as described above, comprising the following steps:

[0019] The bisphenol A type epoxy resin, the cyclodextrin modified epoxy resin toughening agent, the polyurethane modified epoxy resin, the inorganic filler and the latent curing agent are mixed, and then the thixotropic agent is added and mixed to obtain the one-component epoxy adhesive.

[0020] Preferably, after the bisphenol A type epoxy resin, the cyclodextrin modified epoxy resin toughening agent, the polyurethane modified epoxy resin, the inorganic filler and the latent curing agent are mixed, the mixture is first stirred at 40-60°C at a dispersion rate of 60-100 rpm for 0.5-1.5 h, and then stirred at 40-60°C under a vacuum of ≤-0.09 MPa at a dispersion rate of 150-250 rpm for 1-3 h; then the thixotropic agent is added, and the mixture is first stirred at 40-60°C at a dispersion rate of 60-100 rpm for 0.5-1.5 h, and then stirred at 20-30°C under a vacuum of ≤-0.09 MPa at a dispersion rate of 80-120 rpm for 0.5-1.5 h to obtain the one-component adhesive.

[0021] Compared with the prior art, the present application has the following beneficial effects:

[0022] The cyclodextrin modified epoxy resin toughening agent of the present application utilizes the host-guest interaction between cyclodextrin and bisphenol A diglycidyl ether to introduce a slip ring structure into the epoxy resin polymer network, effectively improving the toughness and heat resistance of the epoxy resin, and providing a novel preparation method of an environmentally friendly, efficient and economical epoxy resin toughening agent. Cyclodextrin is a cyclic molecule, and the cavity in the middle has a sufficient size to accommodate bisphenol A diglycidyl ether. Cyclodextrin can be threaded on the epoxy resin to form a slip ring structure. Cyclodextrin reacts with bisphenol A diglycidyl ether to form a slip ring polymer, which forms mechanical interlocking structures such as rotaxanes and catenanes in the polymer network, enhancing the gelation and mechanical strength of the bulk. In addition, the sliding and rotation of the macrocyclic molecule on the chain segment drives the movement of the slip ring polymer network, imparting a unique stress absorption and release mechanism, achieving the purpose of toughening. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1is an infrared spectrum absorption diagram of the cyclodextrin modified epoxy resin toughening agent. DETAILED DESCRIPTION

[0024] The technical solutions of the present application will be described clearly and completely below in combination with the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0025] The present application provides a cyclodextrin modified epoxy resin toughening agent, and the chemical structural formula is as follows:

[0026]

[0027] The epoxy resin toughening agent of the present application utilizes the host-guest interaction between cyclodextrin and bisphenol A diglycidyl ether to introduce a slip ring structure in the epoxy resin polymer network, effectively improving the toughness and heat resistance of the epoxy resin, and providing a novel preparation method of an environmentally friendly, efficient and economical epoxy resin toughening agent. Cyclodextrin is a cyclic molecule, and the cavity in the middle has sufficient size to accommodate bisphenol A diglycidyl ether. Cyclodextrin can form a slip ring structure on the epoxy resin, and the reaction of cyclodextrin and bisphenol A diglycidyl ether forms a slip ring polymer, forming mechanical interlocking structures such as rotaxanes and catenanes in the polymer network, enhancing the gelation and mechanical strength of the bulk; in addition, the sliding and rotation of the macrocyclic molecule on the chain segment drives the activity of the slip ring polymer network, giving it a unique stress absorption and release mechanism to achieve the purpose of toughening.

[0028] The second aspect of the embodiments of the present application provides a preparation method of the cyclodextrin modified epoxy resin toughening agent as described above, comprising the following steps:

[0029] The bisphenol A diglycidyl ether is mixed with β-cyclodextrin, and NaOH is added for reaction to obtain the cyclodextrin modified epoxy resin toughening agent.

[0030] In some embodiments, the reaction temperature is 25-40℃, the molar ratio of β-cyclodextrin to bisphenol A diglycidyl ether is 1:5-20; after the reaction is completed, the pH is adjusted to 6-7 with an acid, then washed at least twice, and dried to obtain the cyclodextrin modified epoxy resin toughening agent.

[0031] The third aspect of the embodiments of the present application provides a one-component epoxy adhesive, comprising the following components in mass fraction:

[0032] The one-component epoxy adhesive formula in the present embodiment comprises 25-50 parts of bisphenol A type epoxy resin, 10-20 parts of cyclodextrin modified epoxy resin as mentioned above, 15-25 parts of polyurethane modified epoxy resin, 10-20 parts of liquid nitrile rubber modified epoxy resin, 15-25 parts of inorganic filler, 1-5 parts of thixotropic agent and 13-20 parts of latent curing agent.

[0033] The one-component epoxy adhesive formula in the present embodiment comprises polyurethane modified epoxy resin, which can crosslink with cyclodextrin modified epoxy resin toughening agent containing cyclodextrin sliding ring to form IPN interpenetrating network, thereby improving the bulk strength of the epoxy adhesive. The polyurethane modified epoxy resin can also improve the adhesion to metal substrates. The liquid nitrile rubber modified epoxy resin forms sea-island structure in the epoxy resin, thereby improving the bulk mechanical strength of the epoxy adhesive. Imidazole as a low-temperature curing agent can quickly cure the epoxy resin at 80-100°C, and is widely used in the fields of automobile, aerospace and electronic adhesives due to its high strength, low energy consumption and simple operation.

[0034] In some embodiments, the bisphenol A type epoxy resin is one or a mixture of several of E51, E54, E44 and E20; preferably one or a mixture of several of BALING PETROCHEMICAL CYD-128, NANYA NPEL-128 and NANYA NPEL-901, and more preferably BALING PETROCHEMICAL CYD-128 and NANYA NPEL-128; and the cyclodextrin is preferably β-cyclodextrin.

[0035] In some embodiments, the polyurethane modified epoxy resin can be ZHUZHOU SHILIN SL-3421 or DOW DER-791; preferably ADEKA EIDICO QR-9466.

[0036] In some embodiments, the liquid nitrile rubber modified epoxy resin is preferably HENSCHEM RA-1340.

[0037] In some embodiments, the cyclodextrin modified epoxy resin toughening agent is a prepolymer of bisphenol A type epoxy resin and cyclodextrin.

[0038] In some embodiments, the inorganic filler can be one or a combination of several of nano calcium carbonate, heavy calcium carbonate, silica powder, mica powder, talc, kaolin; preferably GUANGXI HUANAR CC S-25.

[0039] In some embodiments, the thixotropic agent is a mixture of one or several of fumed silica, hydrogenated castor oil and bentonite, preferably hydrophobic fumed silica, and more preferably CABOT TS620 or WINCREA R202.

[0040] In some embodiments, the latent curing agent is one or a mixture of several of dicyandiamide, imidazole derivatives, polyether amine, preferably imidazole curing agent, and more preferably Ajinomoto PN-23.

[0041] A fourth aspect of the embodiments of the present application provides a preparation method of the one-component epoxy adhesive as described above, comprising the following steps:

[0042] The bisphenol A type epoxy resin, the cyclodextrin modified epoxy resin toughening agent, the polyurethane modified epoxy resin, the inorganic filler, and the latent curing agent are mixed, and then the thixotropic agent is added and mixed to obtain the one-component epoxy adhesive.

[0043] In some embodiments, after the bisphenol A type epoxy resin, the cyclodextrin modified epoxy resin toughening agent, the polyurethane modified epoxy resin, the inorganic filler, and the latent curing agent are mixed, the mixture is first stirred at 40-60°C at a dispersion rate of 60-100 rpm for 0.5-1.5 h, and then stirred at 40-60°C under a vacuum of ≤-0.09 MPa at a dispersion rate of 150-250 rpm for 1-3 h; then the thixotropic agent is added, and the mixture is first stirred at 40-60°C at a dispersion rate of 60-100 rpm for 0.5-1.5 h, and then stirred at 20-30°C under a vacuum of ≤-0.09 MPa at a dispersion rate of 80-120 rpm for 0.5-1.5 h to obtain the one-component adhesive.

[0044] In the preparation method of the embodiments of the present application, the β-cyclodextrin and the bisphenol A diglycidyl ether are stirred at a certain molar ratio, and a NaOH solution is added and stirred at 25-40°C; after the reaction is completed, the pH is adjusted to 6-7 with an acid, and the mixture is washed with deionized water for 2-3 times, and then vacuum dried to obtain the epoxy resin toughening agent. By using the host-guest interaction between the cyclodextrin and the bisphenol A diglycidyl ether, a slip ring structure is introduced into the epoxy resin polymer network, which effectively improves the toughness and heat resistance of the epoxy resin, and provides a novel preparation method of an environmentally friendly, efficient, and economical epoxy resin toughening agent. The cyclodextrin is a cyclic molecule, and the cavity in the middle has a sufficient size to accommodate the bisphenol A diglycidyl ether. The cyclodextrin can be threaded on the epoxy resin to form a slip ring structure. The cyclodextrin reacts with the bisphenol A diglycidyl ether to form a slip ring polymer, which forms mechanical interlocking structures such as rotaxanes and catenanes in the polymer network, thereby enhancing the gelation and mechanical strength of the bulk. In addition, the sliding and rotation of the macrocyclic molecules on the chain segment drive the movement of the slip ring polymer network, which endows it with a unique stress absorption and release mechanism, achieving the toughening purpose.

[0045] Example 1

[0046] The cyclodextrin modified epoxy resin toughening agent of the present embodiment is E51-20-CDs polypluron, and the preparation method of E51-20-CDs polypluron comprises the following steps:

[0047] 78.8g of bisphenol A type epoxy resin E51 was stirred with 11.35g of β-cyclodextrin at a molar ratio of 20:1 at 25°C, 10mL of 0.2mol / L NaOH solution was slowly dropped within 15min, and stirred at 25°C for 60h. After the reaction was completed, 10mL of 0.2mol / L NaOH solution was slowly dropped within 15min, and stirred at 25°C for 60h. After the reaction was completed, pH was adjusted to 7 by adding phosphoric acid, washed with ice water for 3 times, and vacuum dried to obtain E51-20-CDs pluron, which is recorded as β-CD-EP1.

[0048] The epoxy adhesive of the present embodiment comprises the following components in mass fraction:

[0049] 22 parts of bisphenol A type epoxy resin, 15 parts of cyclodextrin modified epoxy resin, 17 parts of polyurethane modified epoxy resin, 10 parts of liquid nitrile rubber modified epoxy resin, 18 parts of inorganic filler, 3 parts of thixotropic agent and 15 parts of latent curing agent.

[0050] The preparation method of the epoxy adhesive of the present embodiment comprises the following steps:

[0051] 22 parts of bisphenol A type epoxy resin, 15 parts of β-CD-EP1, 17 parts of polyurethane modified epoxy resin, 10 parts of liquid nitrile rubber modified epoxy resin, 18 parts of inorganic filler and 15 parts of latent curing agent were mixed in a planetary motion mixer, first stirred at 50°C at a dispersion rate of 80rpm for 1h, and then stirred at 25°C under the condition of vacuum ≤-0.09MPa at a dispersion rate of 200rpm for 2h.

[0052] ≤-0.09MPa at a dispersion rate of 100rpm for 1h to obtain the epoxy adhesive.

[0053] Example 2

[0054] The cyclodextrin modified epoxy resin toughening agent of the present embodiment is different from that of example 1 only in that the molar ratio of bisphenol A type epoxy resin E51 to β-cyclodextrin is different, and the rest is the same. The preparation method of E51-10-CDs polypluron comprises the following steps:

[0055] The 78.8 g of bisphenol A type epoxy resin E51 was stirred with 22.7 g of β-cyclodextrin at a molar ratio of 20:1 at 25 °C, 10 mL of 0.2 mol / L NaOH solution was slowly dropped within 15 min, and stirred at 25 °C for 60 h. After the reaction was completed, the pH was adjusted to 7 by adding phosphoric acid, washed with ice water for 3 times, and vacuum dried to obtain E51-10-CDs rotaxane, which was recorded as β-CD-EP2.

[0056] The epoxy adhesive of the present embodiment comprises the following components by mass fraction:

[0057] The bisphenol A type epoxy resin 22 parts, the cyclodextrin modified epoxy resin 15 parts, the polyurethane modified epoxy resin 17 parts, the liquid butyl nitrile rubber modified epoxy resin 10 parts, the inorganic filler 18 parts, the thixotropic agent 3 parts and the latent curing agent 15 parts.

[0058] The preparation method of the epoxy adhesive of the present embodiment comprises the following steps:

[0059] The 22 parts of bisphenol A type epoxy resin, 15 parts of β-CD-EP2, 17 parts of polyurethane modified epoxy resin, 10 parts of liquid butyl nitrile rubber modified epoxy resin, 18 parts of inorganic filler and 15 parts of latent curing agent were mixed in a planetary motion mixer, first stirred at 50 °C at a dispersion rate of 80 rpm for 1 h, and then stirred at a dispersion rate of 200 rpm under the condition of vacuum ≤-0.09 MPa for 2 h.

[0060] The 3 parts of thixotropic agent were added, first stirred at 50 °C at a dispersion rate of 80 rpm for 1 h, and then stirred at a dispersion rate of 100 rpm under the condition of vacuum ≤-0.09 MPa at 25 °C for 1 h to obtain the epoxy adhesive.

[0061] Example 3

[0062] The cyclodextrin modified epoxy resin toughening agent of the present embodiment is different from that of example 1 only in the molar ratio of bisphenol A type epoxy resin E51 to β-cyclodextrin, and the rest is the same. The preparation method of E51-5-CDs polyrotaxane comprises the following steps:

[0063] The 78.8 g of bisphenol A type epoxy resin E51 was stirred with 45.4 g of β-cyclodextrin at a molar ratio of 20:1 at 25 °C, 10 mL of 0.2 mol / L NaOH solution was slowly dropped within 15 min, and stirred at 25 °C for 60 h. After the reaction was completed, the pH was adjusted to 7 by adding phosphoric acid, washed with ice water for 3 times, and vacuum dried to obtain E51-5-CDs rotaxane, which was recorded as β-CD-EP3.

[0064] The epoxy adhesive of the present embodiment comprises the following components by mass fraction:

[0065] The epoxy adhesive of the embodiment comprises the following components in mass fraction:

[0066] The preparation method of the epoxy adhesive of the embodiment comprises the following steps:

[0067] The 22 parts of bisphenol A type epoxy resin, 15 parts of β-CD-EP3, 17 parts of polyurethane modified epoxy resin, 10 parts of liquid nitrile rubber modified epoxy resin, 18 parts of inorganic filler, and 15 parts of latent curing agent are mixed in a planetary motion mixer, first stirred at a dispersion rate of 80 rpm at 50°C for 1 h, and then stirred at a dispersion rate of 200 rpm under the condition of vacuum ≤-0.09 MPa for 2 h. Then 3 parts of thixotropic agent are added, first stirred at a dispersion rate of 80 rpm at 50°C for 1 h, and then stirred at a dispersion rate of 100 rpm under the condition of vacuum ≤-0.09 MPa at 25°C for 1 h, to obtain the epoxy adhesive.

[0068] Example 4

[0069] The β-cyclodextrin modified epoxy resin toughening agent of the embodiment is different from that of Example 1 only in that the molar ratio of bisphenol A type epoxy resin E51 to β-cyclodextrin is different, and the rest is the same. The preparation method of E51-2-CDs polyrotaxane comprises the following steps:

[0070] The 78.8g of bisphenol A type epoxy resin E51 is stirred with 113.5g of β-cyclodextrin at a molar ratio of 20:1 at 25°C, 100mL of 0.2mol / L NaOH solution is slowly added dropwise within 15min, and stirred at 25°C for 60h. After the reaction is completed, add phosphoric acid to adjust the pH to 7, wash with ice water for 3 times, and vacuum dry to obtain E51-2-CDs rotaxane, which is recorded as β-CD-EP4.

[0071] The epoxy adhesive of the embodiment comprises the following components in mass fraction:

[0072] The epoxy adhesive of the embodiment comprises the following components in mass fraction:

[0073] The preparation method of the epoxy adhesive of the embodiment comprises the following steps:

[0074] 22 parts of bisphenol A type epoxy resin, 15 parts of β-CD-EP4, 17 parts of polyurethane modified epoxy resin, 10 parts of liquid nitrile rubber modified epoxy resin, 18 parts of inorganic filler, and 15 parts of latent curing agent were mixed in a planetary mixer. The mixture was first stirred at 50°C at a dispersion rate of 80 rpm for 1 hour, and then further stirred under vacuum.

[0075] Stir at a dispersion rate of 200 rpm for 2 hours under a pressure of ≤-0.09 MPa. Then add 3 parts of thixotropic agent, first stir at a dispersion rate of 80 rpm for 1 hour at 50℃, and then stir at a dispersion rate of 100 rpm for 1 hour at 25℃ and a vacuum of ≤-0.09 MPa to obtain epoxy adhesive.

[0076] Example 5

[0077] The epoxy adhesive of this embodiment comprises the following components in parts by weight:

[0078] The mixture contains 17 parts of bisphenol A type epoxy resin, 20 parts of cyclodextrin modified epoxy resin, 17 parts of polyurethane modified epoxy resin, 10 parts of liquid nitrile rubber modified epoxy resin, 18 parts of inorganic filler, 3 parts of thixotropic agent, and 15 parts of latent curing agent.

[0079] The method for preparing the epoxy adhesive in this embodiment includes the following steps:

[0080] 17 parts of bisphenol A type epoxy resin, 20 parts of β-CD-EP1, 17 parts of polyurethane modified epoxy resin, 10 parts of liquid nitrile rubber modified epoxy resin, 18 parts of inorganic filler, and 15 parts of latent curing agent were mixed in a planetary mixer. The mixture was first stirred at 50°C at a dispersion rate of 80 rpm for 1 hour, and then stirred under vacuum.

[0081] Stir at a dispersion rate of 200 rpm for 2 hours under a pressure of ≤-0.09 MPa. Then add 3 parts of thixotropic agent, first stir at a dispersion rate of 80 rpm for 1 hour at 50℃, and then stir at a dispersion rate of 100 rpm for 1 hour at 25℃ and a vacuum of ≤-0.09 MPa to obtain epoxy adhesive.

[0082] Example 6

[0083] The cyclodextrin-modified epoxy resin toughening agent of this embodiment has the structural formula E51-20-CDs polyrotaxane. The preparation method of E51-20-CDs polyrotaxane includes the following steps:

[0084] 78.8g of bisphenol A type epoxy resin E51 was stirred with 11.35g of β-cyclodextrin at a molar ratio of 20:1 at 25°C, 10mL of 0.2mol / L NaOH solution was slowly dropped within 15min, and stirred at 25°C for 60h. After the reaction was completed, pH was adjusted to 7 by dropping phosphoric acid, washed with ice water for 3 times, and vacuum dried to obtain E51-20-CDs rotaxane, which was recorded as β-CD-EP1.

[0085] The epoxy adhesive of the present embodiment comprises the following components in mass fraction:

[0086] 25 parts of bisphenol A type epoxy resin, 10 parts of β-CD-EP1, 15 parts of polyurethane modified epoxy resin, 15 parts of liquid nitrile rubber modified epoxy resin, 15 parts of inorganic filler, 13 parts of latent curing agent.

[0087] The preparation method of the epoxy adhesive of the present embodiment comprises the following steps:

[0088] 25 parts of bisphenol A type epoxy resin, 10 parts of β-CD-EP1, 15 parts of polyurethane modified epoxy resin, 15 parts of liquid nitrile rubber modified epoxy resin, 15 parts of inorganic filler, 13 parts of latent curing agent.

[0089] ≤-0.09MPa at a dispersion rate of 200rpm for 2h. Then 3 parts of thixotropic agent was added, first stirred at 50°C at a dispersion rate of 80rpm for 1h, and then stirred at 25°C under the condition of vacuum ≤-0.09MPa at a dispersion rate of 100rpm for 1h to obtain the epoxy adhesive.

[0090] Example 7

[0091] The cyclodextrin modified epoxy resin toughener of the present embodiment has a structure of E51-20-CDs polyrotaxane, and the preparation method of E51-20-CDs polyrotaxane comprises the following steps:

[0092] 78.8g of bisphenol A type epoxy resin E51 was stirred with 11.35g of β-cyclodextrin at a molar ratio of 20:1 at 25°C, 10mL of 0.2mol / L NaOH solution was slowly dropped within 15min, and stirred at 25°C for 60h. After the reaction was completed, pH was adjusted to 7 by dropping phosphoric acid, washed with ice water for 3 times, and vacuum dried to obtain E51-20-CDs rotaxane, which was recorded as β-CD-EP1.

[0093] The epoxy adhesive of the present embodiment comprises the following components in mass fraction:

[0094] Bisphenol A type epoxy resin 50 parts, cyclodextrin modified epoxy resin 15 parts, polyurethane modified epoxy resin 25 parts, liquid butyronitrile rubber modified epoxy resin 20 parts, inorganic filler 25 parts, thixotropic agent 5 parts and latent curing agent 20 parts.

[0095] The preparation method of the epoxy adhesive of the present embodiment comprises the following steps:

[0096] The 50 parts of bisphenol A type epoxy resin, 15 parts of β-CD-EP1, 25 parts of polyurethane modified epoxy resin, 20 parts of liquid butyronitrile rubber modified epoxy resin, 25 parts of inorganic filler and 20 parts of latent curing agent are mixed in a planetary motion mixer, first stirred at a dispersion rate of 80 rpm at 50°C for 1 h, and then stirred at a dispersion rate of 200 rpm under the condition of vacuum ≤-0.09 MPa for 2 h.

[0097] The 50 parts of bisphenol A type epoxy resin, 15 parts of β-CD-EP1, 25 parts of polyurethane modified epoxy resin, 20 parts of liquid butyronitrile rubber modified epoxy resin, 25 parts of inorganic filler and 20 parts of latent curing agent are mixed in a planetary motion mixer, first stirred at a dispersion rate of 80 rpm at 50°C for 1 h, and then stirred at a dispersion rate of 200 rpm under the condition of vacuum ≤-0.09 MPa for 2 h.

[0098] Comparative Example 1

[0099] The epoxy adhesive of the present embodiment comprises the following components in mass parts:

[0100] Bisphenol A type epoxy resin 37 parts, polyurethane modified epoxy resin 17 parts, liquid butyronitrile rubber modified epoxy resin 10 parts, inorganic filler 18 parts, thixotropic agent 3 parts and latent curing agent 15 parts.

[0101] The preparation method of the epoxy adhesive of the present embodiment comprises the following steps:

[0102] The 37 parts of bisphenol A type epoxy resin, 17 parts of polyurethane modified epoxy resin, 10 parts of liquid butyronitrile rubber modified epoxy resin, 18 parts of inorganic filler and 15 parts of latent curing agent are mixed in a planetary motion mixer, first stirred at a dispersion rate of 80 rpm at 50°C for 1 h, and then stirred at a dispersion rate of 200 rpm under the condition of vacuum ≤-0.09 MPa for 2 h. Then 3 parts of thixotropic agent are added, first stirred at a dispersion rate of 80 rpm at 50°C for 1 h, and then stirred at a dispersion rate of 100 rpm at 25°C under the condition of vacuum ≤-0.09 MPa for 1 h to obtain the epoxy adhesive.

[0103] Comparative Example 2

[0104] The epoxy adhesive of the present embodiment comprises the following components in mass parts:

[0105] 32 parts of bisphenol A type epoxy resin, 22 parts of polyurethane modified epoxy resin, 10 parts of liquid nitrile rubber modified epoxy resin, 18 parts of inorganic filler, 3 parts of thixotropic agent and 15 parts of latent curing agent.

[0106] The preparation method of the epoxy adhesive of the embodiment comprises the following steps:

[0107] 32 parts of bisphenol A type epoxy resin, 22 parts of polyurethane modified epoxy resin, 10 parts of liquid nitrile rubber modified epoxy resin, 18 parts of inorganic filler, 15 parts of latent curing agent are mixed in a planetary motion mixer, first stirred at a dispersion rate of 80 rpm at 50℃ for 1h, then stirred at a dispersion rate of 200 rpm under the condition of vacuum ≤-0.09 MPa for 2h. Then 3 parts of thixotropic agent is added, first stirred at a dispersion rate of 80 rpm at 50℃ for 1h, then stirred at a dispersion rate of 100 rpm under the condition of vacuum ≤-0.09 MPa at 25℃ for 1h, to obtain the epoxy adhesive.

[0108] The component selection and the ratio of each embodiment and the comparative example are shown in Table 1, and the curing conditions are in accordance with the standard 90℃×60min; the shear strength is in accordance with the standard GB / T 7124-2008, the determination of adhesive tensile shear strength of rigid material to rigid material, the substrate is anodized aluminum 5754; the T-peeling degree is in accordance with the standard GB / T 2791-1995, the adhesive T-peeling strength test method of flexible material to flexible material, the substrate is anodized aluminum 5754; the tensile strength and the elongation at break are in accordance with the standard GB / T 528-2009, the determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber; the heat aging resistance is in accordance with the standard: after curing, the test piece is placed at 70℃ for 168h, and then is placed at room temperature for 24h; the high-low temperature alternation is in accordance with the standard: after curing, the test piece is placed at 50℃ for 4h, is decreased to-40℃ within 2h, is placed at-40℃ for 4h, is increased to 50℃ within 2h, and the cycle is repeated. The amount of each component in Table 1 is in parts by weight.

[0109] Table 1. Component selection and ratio data table of examples and comparative examples

[0110]

[0111] The test results are shown in Table 2. As can be seen from the experimental results in Table 2, the one-component epoxy adhesives of Examples 1-7 prepared by using the cyclodextrin modified epoxy resin toughening agent synthesized in the application all have good tensile strength, shear strength and peeling strength, and the shear strength at 80℃, the heat aging shear strength and the high-low temperature alternation shear strength are all better than those of Comparative Examples 1 and 2. The introduction of cyclodextrin and the formation of slip ring polymer improve the toughness, mechanical properties and tensile properties of the epoxy resin composition, and the toughening effect is significant.

[0112] Table 2. Test results of examples and comparative examples

[0113]

[0114] It is apparent that the above-mentioned embodiments are only examples for clearly illustrating the present application and are not intended to limit the present application. Based on the above-mentioned description, other different forms of changes or variations can be made by those skilled in the art. It is not necessary or possible to enumerate all the embodiments.

[0115] The obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A method for preparing a cyclodextrin-modified epoxy resin toughener, characterized by, The method comprises the following steps: The bisphenol A diglycidyl ether is mixed with β-cyclodextrin, NaOH is added for reaction, and the cyclodextrin modified epoxy resin toughening agent is obtained; The reaction temperature is 25-40℃, and the molar ratio of the β-cyclodextrin to the bisphenol A diglycidyl ether is 1:5-20; After the reaction is completed, the pH is adjusted to 6-7 with an acid, then the cyclodextrin modified epoxy resin toughening agent is washed at least twice and dried.

2. A cyclodextrin modified epoxy resin toughening agent prepared by the method of claim 1.

3. A one-component epoxy adhesive, characterized in that The components include the following mass fractions: The bisphenol A type epoxy resin is 25-50 parts, the cyclodextrin modified epoxy resin of claim 2 is 10-20 parts, the polyurethane modified epoxy resin is 15-25 parts, the liquid butyronitrile rubber modified epoxy resin is 10-20 parts, the inorganic filler is 15-25 parts, the thixotropic agent is 1-5 parts, and the latent curing agent is 13-20 parts.

4. The one-component epoxy adhesive of claim 3, wherein: The bisphenol A type epoxy resin is one or a mixture of several of E51, E54, E44 and E20.

5. The one-component epoxy adhesive of claim 3, wherein: The inorganic filler is one or a combination of several of nano calcium carbonate, heavy calcium, silica powder, mica powder, talc, kaolin.

6. The one-component epoxy adhesive of claim 3, wherein: The latent curing agent is one or a combination of several of dicyandiamide and imidazole derivatives.

7. The one-component epoxy adhesive of claim 3, wherein: The thixotropic agent is one or a combination of several of fumed silica, hydrogenated castor oil and bentonite.

8. A process for the preparation of a one-part epoxy adhesive as claimed in any one of claims 3 to 7, characterised in that, The method comprises the following steps: The bisphenol A type epoxy resin, the cyclodextrin modified epoxy resin toughening agent, the polyurethane modified epoxy resin, the liquid butyronitrile rubber modified epoxy resin, the inorganic filler and the latent curing agent are mixed, and then the thixotropic agent is added for mixing, so that the one-component epoxy adhesive is obtained.

9. The method for preparing the one-component epoxy adhesive according to claim 8, characterized in that, The method comprises the following steps: The bisphenol A type epoxy resin, the cyclodextrin modified epoxy resin toughening agent, the polyurethane modified epoxy resin, the liquid butyronitrile rubber modified epoxy resin, the inorganic filler and the latent curing agent are mixed, and then the thixotropic agent is added for mixing, so that the one-component epoxy adhesive is obtained. The method comprises the following steps: The bisphenol A type epoxy resin, the cyclodextrin modified epoxy resin toughening agent, the polyurethane modified epoxy resin, the liquid butyronitrile rubber modified epoxy resin, the inorganic filler and the latent curing agent are mixed, and then the thixotropic agent is added for mixing, so that the one-component epoxy adhesive is obtained.

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