Cyclodextrin modified epoxy resin flexibilizer, epoxy adhesive and preparation method thereof

Abstract

The invention provides a cyclodextrin modified epoxy resin flexibilizer, an epoxy adhesive and a preparation method of the cyclodextrin modified epoxy resin flexibilizer. The chemical structural formula of the cyclodextrin modified epoxy resin flexibilizer is as shown in a formula 1: # imgabs0. The cyclodextrin modified epoxy resin flexibilizer is excellent in mechanical strength and temperature resistance, low in production cost, easy to synthesize, non-toxic and environment-friendly.

Description

Technical Field

[0001] The invention belongs to the field of composite materials, and specifically relates to a cyclodextrin-modified epoxy resin toughener, an epoxy adhesive and a preparation method thereof. Background Art

[0002] Epoxy resin has excellent mechanical strength, adhesion, thermal stability and chemical stability, and is widely used in adhesives, coatings and composite materials. In the field of automobile manufacturing, epoxy structural adhesive is a new body connection process with advantages such as light weight, high mechanical strength, reduced stress concentration and good sealing, and is gradually replacing welding technology. However, the epoxy resin itself is relatively brittle and has poor impact resistance. In order to make epoxy structural adhesive meet actual production needs, toughening agents need to be added.

[0003] At present, the main ideas for toughening epoxy resins are as follows: (1) using elastomers, thermoplastic resins or rigid particles as a second phase to form an "island structure" with the epoxy resin body for toughening; (2) using thermoplastic resins to penetrate the epoxy resin to form a molecular interpenetrating network (IPN) for toughening; (3) adding flexible segments to improve the activity of network molecules for toughening. Commonly used toughening agents include carboxyl-terminated liquid nitrile rubber (CTBN), blocked isocyanates, polyetheretherketone (PEEK), core-shell nanoparticles, etc. However, most of the above toughening agents are complex to synthesize, have high production costs, and the intermediates produced have certain toxicity and cannot improve the gelation performance of epoxy resins, which limits the application of the above toughening agents in high-performance epoxy adhesives.

[0004] For example, a Chinese patent document with publication number CN117683155A discloses an epoxidized star-shaped polybutadiene toughening agent, a preparation method and an application thereof, wherein a star-shaped polybutadiene liquid rubber is synthesized by an anionic polymerization method, wherein the single-arm Mn is 3000-8000, the number of arms is 7-10, the coupling efficiency is 75%-95%, and the vinyl content is 10%-90%; the obtained star-shaped polybutadiene liquid rubber is epoxidized with an organic acid and hydrogen peroxide to obtain an epoxidized star-shaped polybutadiene liquid rubber with an epoxidation degree of 45%-60%; and the epoxidized star-shaped polybutadiene liquid rubber is used as After the toughening agent is added to the epoxy resin matrix, it can be evenly dispersed in the epoxy resin, co-cured, reduce the crosslinking density, and significantly improve the impact strength of the epoxy resin, while basically not losing mechanical properties. However, this epoxidized 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 using end-group epoxy block liquid crystals, which can increase the impact strength of the epoxy resin by 5 to 8 kJ / ㎡, 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 method for preparing an epoxy resin toughening agent which has excellent mechanical strength and temperature resistance, low production cost, is easy to synthesize, and is non-toxic and environmentally friendly. Summary of the invention

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

[0007] In order to solve the above problems, the first aspect of the present invention provides a cyclodextrin-modified epoxy resin toughening agent, whose chemical structural formula is:

[0008]

[0009] The second aspect of the present invention provides a method for preparing the cyclodextrin-modified epoxy resin toughening agent as described above, comprising the following steps:

[0010] Bisphenol A diglycidyl ether and beta-cyclodextrin are mixed, and NaOH is added to react to obtain the cyclodextrin-modified epoxy resin toughening agent.

[0011] Preferably, the reaction temperature is 25-40° C., 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 acid, and then washed at least twice and dried to obtain the cyclodextrin-modified epoxy resin toughener.

[0012] The third aspect of the present invention provides a one-component epoxy adhesive comprising the following components in parts by weight:

[0013] 25-50 parts of bisphenol A 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.

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

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

[0016] Preferably, the latent curing agent is one or a combination of dicyandiamide, imidazole derivatives or polyetheramine.

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

[0018] A fourth aspect of the present invention provides a method for preparing the one-component epoxy adhesive as described above, comprising the following steps:

[0019] The bisphenol A 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 mixing the bisphenol A epoxy resin, the cyclodextrin modified epoxy resin toughening agent, the polyurethane modified epoxy resin, the inorganic filler, and the latent curing agent, they are first stirred at a dispersion rate of 60rpm to 100rpm at 40°C to 60°C for 0.5h to 1.5h, and then stirred at a dispersion rate of 150rpm to 250rpm at 40°C to 60°C and vacuum ≤-0.09MPa for 1h to 3h; then the thixotropic agent is added, first stirred at a dispersion rate of 60rpm to 100rpm at 40°C to 60°C for 0.5h to 1.5h, and then stirred at a dispersion rate of 80rpm to 120rpm at 20°C to 30°C and vacuum ≤-0.09MPa for 0.5h to 1.5h to obtain the one-component adhesive.

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

[0022] The cyclodextrin modified epoxy resin toughener of the present invention utilizes the host-guest interaction between cyclodextrin and bisphenol A diglycidyl ether to introduce a sliding ring structure into the epoxy resin polymer network, effectively improve the toughness and heat resistance of the epoxy resin, and provide a novel environmentally friendly, efficient and economical preparation method of the epoxy resin toughener. Cyclodextrin is a cyclic molecule, and the cavity in the middle is large enough to accommodate bisphenol A diglycidyl ether. Cyclodextrin can be strung on the epoxy resin to form a sliding ring structure. Cyclodextrin and bisphenol A diglycidyl ether are reacted to form a sliding ring polymer, and mechanical interlocking structures such as rotaxane and catenane are formed in the polymer network, which enhances the gelation and mechanical strength of the body; in addition, the sliding and rotation of the macrocyclic molecule on the chain segment drives the activity of the sliding ring polymer network, giving it a unique stress absorption and release mechanism to achieve the purpose of toughening. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1It is the infrared spectrum absorption diagram of the cyclodextrin modified epoxy resin toughening agent described in the embodiment of the present invention. DETAILED DESCRIPTION

[0024] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solution of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] The embodiment of the present invention provides a cyclodextrin-modified epoxy resin toughening agent, the chemical structural formula of which is:

[0026]

[0027] The epoxy resin toughening agent of the present invention utilizes the host-guest interaction between cyclodextrin and bisphenol A diglycidyl ether to introduce a sliding ring structure into the epoxy resin polymer network, effectively improves the toughness and heat resistance of the epoxy resin, and provides a novel environmentally friendly, efficient and economical preparation method of the epoxy resin toughening agent. Cyclodextrin is a cyclic molecule, and the cavity in the middle is large enough to accommodate bisphenol A diglycidyl ether. Cyclodextrin can be strung on the epoxy resin to form a sliding ring structure. Cyclodextrin and bisphenol A diglycidyl ether are reacted to form a sliding ring polymer, and mechanical interlocking structures such as rotaxane and catenane are formed in the polymer network, which enhances the gelation and mechanical strength of the body; in addition, the sliding and rotation of the macrocyclic molecule on the chain segment drives the activity of the sliding ring polymer network, giving it a unique stress absorption and release mechanism to achieve the purpose of toughening.

[0028] A second aspect of an embodiment of the present invention provides a method for preparing the cyclodextrin-modified epoxy resin toughening agent as described above, comprising the following steps:

[0029] Bisphenol A diglycidyl ether and beta-cyclodextrin are mixed, and NaOH is added to react to obtain the cyclodextrin-modified epoxy resin toughening agent.

[0030] In some embodiments, the reaction temperature is 25-40° C., and 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 acid, and then washed at least twice and dried to obtain the cyclodextrin-modified epoxy resin toughening agent.

[0031] A third aspect of an embodiment of the present invention provides a one-component epoxy adhesive comprising the following components in parts by weight:

[0032] 25-50 parts of bisphenol A 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] In the one-component epoxy adhesive formula involved in this embodiment, polyurethane-modified epoxy resin is added. On the one hand, it can be used as a cross-linking agent to cross-link with the cyclodextrin-modified epoxy resin toughening agent containing cyclodextrin sliding ring to form an IPN interpenetrating network, thereby improving the bulk strength of the epoxy adhesive; on the other hand, it can improve the bonding ability to the metal substrate. Liquid nitrile rubber-modified epoxy resin forms a sea-island structure in the epoxy resin, thereby improving the mechanical strength of the epoxy adhesive. As a medium- and low-temperature curing agent, imidazole can quickly cure epoxy resin at 80-100°C. It has high strength, low energy consumption and simple operation, and is widely used in the fields of automobiles, aerospace and electronic adhesives.

[0034] In some embodiments, the bisphenol A epoxy resin is a mixture of one or more of E51, E54, E44 and E20; preferably, it is a mixture of one or more of Baling Petrochemical CYD-128, Nanya NPEL-128 and Nanya NPEL-901, more preferably Baling Petrochemical CYD-128 and Nanya NPEL-128; the cyclodextrin is preferably β-cyclodextrin.

[0035] In some embodiments, the polyurethane modified epoxy resin may be Zhuzhou Shilin SL-3421, Dow Chemical DER-791, or preferably ADEKA QR-9466.

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

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

[0038] In some embodiments, the inorganic filler can be one or a combination of nano calcium carbonate, heavy calcium carbonate, silica powder, mica powder, talc powder, kaolin, and preferably Guangxi Warner CCS-25.

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

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

[0041] A fourth aspect of an embodiment of the present invention provides a method for preparing the one-component epoxy adhesive as described above, comprising the following steps:

[0042] The bisphenol A 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 epoxy resin, the cyclodextrin modified epoxy resin toughening agent, the polyurethane modified epoxy resin, the inorganic filler, and the latent curing agent are mixed, they are first stirred at a dispersion rate of 60rpm to 100rpm at 40°C to 60°C for 0.5h to 1.5h, and then stirred at a dispersion rate of 150rpm to 250rpm at 40°C to 60°C and vacuum ≤-0.09MPa for 1h to 3h; then the thixotropic agent is added, first stirred at a dispersion rate of 60rpm to 100rpm at 40°C to 60°C for 0.5h to 1.5h, and then stirred at a dispersion rate of 80rpm to 120rpm at 20°C to 30°C and vacuum ≤-0.09MPa for 0.5h to 1.5h to obtain the one-component adhesive.

[0044] The preparation method of the embodiment of the present invention comprises stirring the β-cyclodextrin and the bisphenol A diglycidyl ether in a certain molar ratio, adding a NaOH solution and stirring at 25 to 40°C; adjusting the pH to 6 to 7 with an acid after the reaction is completed, adding deionized water for washing 2 to 3 times, and vacuum drying to obtain the epoxy resin toughening agent. By utilizing the host-guest interaction between cyclodextrin and bisphenol A diglycidyl ether, a sliding ring structure is introduced into the epoxy resin polymer network, effectively improving the toughness and heat resistance of the epoxy resin, and providing a novel environmentally friendly, efficient and economical preparation method for an epoxy resin toughening agent. Cyclodextrin is a cyclic molecule with a cavity in the middle that is large enough to accommodate bisphenol A diglycidyl ether. Cyclodextrin can be strung on epoxy resin to form a sliding ring structure. Cyclodextrin and bisphenol A diglycidyl ether are reacted to form a sliding ring polymer, which forms mechanical interlocking structures such as rotaxanes and catenanes in the polymer network, enhancing the gelation and mechanical strength of the body. In addition, the sliding and rotation of the macrocyclic molecules on the chain segments drive the activity of the sliding ring polymer network, giving it a unique stress absorption and release mechanism to achieve the purpose of toughening.

[0045] Example 1

[0046] The cyclodextrin-modified epoxy resin toughener of this embodiment is E51-20-CDs polyrotaxane, and the preparation method of E51-20-CDs polyrotaxane comprises the following steps:

[0047] 78.8 g of bisphenol A epoxy resin E51 and 11.35 g of β-cyclodextrin were stirred at 25°C in a molar ratio of 20:1, 10 mL of 0.2 mol / L NaOH solution was slowly added dropwise within 15 min, and stirred at 25°C for 60 h. After the reaction, phosphoric acid was added dropwise to adjust the pH to 7, and ice water was added to wash 3 times, and vacuum dried to obtain E51-20-CDs rotaxane, which was recorded as β-CD-EP1.

[0048] The epoxy adhesive of this embodiment includes the following components in parts by weight:

[0049] 22 parts of bisphenol A 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 this embodiment comprises the following steps:

[0051] 22 parts of bisphenol A 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 mixer, first stirred at 50°C at a dispersion rate of 80 rpm for 1 h, and then placed in a vacuum mixer.

[0052] ≤-0.09MPa, and stirred at a dispersion rate of 200rpm for 2h. Then 3 parts of thixotropic agent were added, and stirred at a dispersion rate of 80rpm for 1h at 50°C, and then stirred at a dispersion rate of 100rpm for 1h at 25°C and vacuum ≤-0.09MPa to obtain epoxy adhesive.

[0053] Example 2

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

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

[0056] The epoxy adhesive of this embodiment includes the following components in parts by weight:

[0057] 22 parts of bisphenol A 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.

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

[0059] 22 parts of bisphenol A epoxy resin, 15 parts of β-CD-EP2, 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, first stirred at 50°C at a dispersion rate of 80 rpm for 1 h, and then vacuum-mixed.

[0060] ≤-0.09MPa, and stirred at a dispersion rate of 200rpm for 2h. Then 3 parts of thixotropic agent were added, and stirred at a dispersion rate of 80rpm for 1h at 50°C, and then stirred at a dispersion rate of 100rpm for 1h at 25°C and vacuum ≤-0.09MPa to obtain epoxy adhesive.

[0061] Example 3

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

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

[0064] The epoxy adhesive of this embodiment includes the following components in parts by weight:

[0065] 22 parts of bisphenol A 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.

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

[0067] 22 parts of bisphenol A 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 were mixed in a planetary mixer, first stirred at 50°C at a dispersion rate of 80 rpm for 1 hour, and then stirred at a dispersion rate of 200 rpm for 2 hours under the condition of vacuum ≤-0.09 MPa. Then 3 parts of thixotropic agent were added, first stirred at 50°C at a dispersion rate of 80 rpm for 1 hour, and then stirred at a dispersion rate of 100 rpm for 1 hour under the condition of 25°C and vacuum ≤-0.09 MPa to obtain epoxy adhesive.

[0068] Example 4

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

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

[0071] The epoxy adhesive of this embodiment includes the following components in parts by weight:

[0072] 22 parts of bisphenol A 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.

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

[0074] 22 parts of bisphenol A 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, first stirred at 50°C at a dispersion rate of 80 rpm for 1 h, and then placed in a vacuum mixer.

[0075] ≤-0.09MPa, and stirred at a dispersion rate of 200rpm for 2h. Then 3 parts of thixotropic agent were added, and stirred at a dispersion rate of 80rpm for 1h at 50°C, and then stirred at a dispersion rate of 100rpm for 1h at 25°C and vacuum ≤-0.09MPa to obtain epoxy adhesive.

[0076] Example 5

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

[0078] 17 parts of bisphenol A 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 preparation method of the epoxy adhesive of this embodiment comprises the following steps:

[0080] 17 parts of bisphenol A 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, first stirred at 50°C at a dispersion rate of 80 rpm for 1 h, and then vacuum-mixed.

[0081] ≤-0.09MPa, and stirred at a dispersion rate of 200rpm for 2h. Then 3 parts of thixotropic agent were added, and stirred at a dispersion rate of 80rpm for 1h at 50°C, and then stirred at a dispersion rate of 100rpm for 1h at 25°C and vacuum ≤-0.09MPa to obtain epoxy adhesive.

[0082] Example 6

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

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

[0085] The epoxy adhesive of this embodiment includes the following components in parts by weight:

[0086] 25 parts of bisphenol A epoxy resin, 10 parts of cyclodextrin modified epoxy resin, 15 parts of polyurethane modified epoxy resin, 15 parts of liquid nitrile rubber modified epoxy resin, 15 parts of inorganic filler, 1 part of thixotropic agent and 13 parts of latent curing agent.

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

[0088] 25 parts of bisphenol A 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, and 13 parts of latent curing agent were mixed in a planetary mixer, first stirred at 50°C at a dispersion rate of 80 rpm for 1 h, and then placed in a vacuum mixer.

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

[0090] Example 7

[0091] The cyclodextrin-modified epoxy resin toughener of this embodiment has a structural formula of E51-20-CDs polyrotaxane. The preparation method of E51-20-CDs polyrotaxane comprises the following steps:

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

[0093] The epoxy adhesive of this embodiment includes the following components in parts by weight:

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

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

[0096] 50 parts of bisphenol A epoxy resin, 15 parts of β-CD-EP1, 25 parts of polyurethane modified epoxy resin, 20 parts of liquid nitrile rubber modified epoxy resin, 25 parts of inorganic filler, and 20 parts of latent curing agent were mixed in a planetary mixer, first stirred at 50°C at a dispersion rate of 80 rpm for 1 h, and then vacuum-mixed.

[0097] ≤-0.09MPa, and stirred at a dispersion rate of 200rpm for 2h. Then 3 parts of thixotropic agent were added, and stirred at a dispersion rate of 80rpm for 1h at 50°C, and then stirred at a dispersion rate of 100rpm for 1h at 25°C and vacuum ≤-0.09MPa to obtain epoxy adhesive.

[0098] Comparative Example 1

[0099] The epoxy adhesive of this embodiment includes the following components in parts by weight:

[0100] 37 parts of bisphenol A 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.

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

[0102] 37 parts of bisphenol A epoxy resin, 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, first stirred at 50°C at a dispersion rate of 80 rpm for 1 hour, and then stirred at a dispersion rate of 200 rpm for 2 hours under the condition of vacuum ≤-0.09 MPa. Then 3 parts of thixotropic agent were added, first stirred at 50°C at a dispersion rate of 80 rpm for 1 hour, and then stirred at a dispersion rate of 100 rpm for 1 hour under the condition of 25°C and vacuum ≤-0.09 MPa to obtain epoxy adhesive.

[0103] Comparative Example 2

[0104] The epoxy adhesive of this embodiment includes the following components in parts by weight:

[0105] 32 parts of bisphenol A 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 this embodiment comprises the following steps:

[0107] 32 parts of bisphenol A epoxy resin, 22 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, first stirred at 50°C at a dispersion rate of 80 rpm for 1 hour, and then stirred at a dispersion rate of 200 rpm for 2 hours under the condition of vacuum ≤-0.09 MPa. Then 3 parts of thixotropic agent were added, first stirred at 50°C at a dispersion rate of 80 rpm for 1 hour, and then stirred at a dispersion rate of 100 rpm for 1 hour under the condition of 25°C and vacuum ≤-0.09 MPa to obtain epoxy adhesive.

[0108] The selection and proportion of the components obtained in the above embodiments and comparative examples are shown in Table 1. The curing conditions are in accordance with the standard 90°C×60min; the shear strength is in accordance with the standard GB / T 7124-2008, the determination of the tensile shear strength of the adhesive is rigid material to rigid material, and the substrate is anodized aluminum 5754; the T-type peeling degree is in accordance with the standard GB / T 2791-1995, the adhesive T peeling strength test method is flexible material to flexible material, and the substrate is anodized aluminum 5754; the tensile strength and 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; heat aging is in accordance with the standard: after the test piece is cured, it is placed at 70°C for 168h, and then placed at room temperature for 24h after being taken out; high and low temperature alternation is in accordance with the standard: after the test piece is cured, it undergoes the following cycle: placed at 50°C for 4h, and dropped to -40°C within 2h; -40°C, 4h, and raised to 50°C within 2h; the cycle is repeated. The amounts of the components in Table 1 are by weight.

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

[0110]

[0111] The test results are shown in Table 2 below. From the experimental results in Table 2, it can be seen that the one-component epoxy adhesives of Examples 1-7 prepared using the cyclodextrin-modified epoxy resin toughening agent synthesized by the present invention have relatively good tensile strength, shear strength and peel strength, and the 80°C shear strength, heat aging shear strength, and high and low temperature alternating shear strength are better than those of Comparative Examples 1 and 2. The introduction of cyclodextrin and the formation of the sliding 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 embodiments and comparative examples

[0113]

[0114] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here.

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

Claims

1. A cyclodextrin modified epoxy resin toughening agent, characterized in that: Its chemical structure is shown in Formula 1 below:

2. A method for preparing the cyclodextrin-modified epoxy resin toughening agent according to claim 1, characterized in that: The following steps are involved: Bisphenol A diglycidyl ether and beta-cyclodextrin are mixed, and NaOH is added to react to obtain the cyclodextrin-modified epoxy resin toughening agent.

3. The method for preparing the cyclodextrin modified epoxy resin toughening agent according to claim 2, characterized in that: Also includes: The reaction temperature is 25 to 40° C., and the molar ratio of the β-cyclodextrin to the bisphenol A diglycidyl ether is 1:5 to 20; After the reaction is completed, the pH value is adjusted to 6-7 with acid, and then washed at least twice and dried to obtain the cyclodextrin modified epoxy resin toughening agent.

4. A one-component epoxy adhesive, characterized in that: The composition includes the following components in parts by weight: 25-50 parts of bisphenol A epoxy resin, 10-20 parts of cyclodextrin modified epoxy resin as claimed in claim 1, 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.

5. The one-component epoxy adhesive according to claim 4, characterized in that: The bisphenol A epoxy resin is one of E51, E54, E44 and E20 or a mixture of several thereof.

6. The one-component epoxy adhesive according to claim 4, characterized in that: The inorganic filler is one or a combination of nano calcium carbonate, heavy calcium, silicon powder, mica powder, talc powder and kaolin.

7. The one-component epoxy adhesive according to claim 4, characterized in that: The latent curing agent is one or a combination of dicyandiamide, imidazole derivatives or polyetheramine.

8. The one-component epoxy adhesive according to claim 4, characterized in that: The thixotropic agent is one or a combination of fumed silica, hydrogenated castor oil or bentonite.

9. A method for preparing a one-component epoxy adhesive as claimed in any one of claims 4 to 8, characterized in that: The following steps are involved: The bisphenol A 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.

10. The method for preparing a one-component epoxy adhesive according to claim 9, characterized in that: The specific steps include: After mixing the bisphenol A epoxy resin, the cyclodextrin modified epoxy resin toughening agent, the polyurethane modified epoxy resin, the inorganic filler and the latent curing agent, the mixture is first stirred at a dispersion rate of 60rpm to 100rpm at 40°C to 60°C for 0.5h to 1.5h, and then stirred at a dispersion rate of 150rpm to 250rpm at 40°C to 60°C and vacuum ≤-0.09MPa for 1h to 3h; then the thixotropic agent is added, and the mixture is first stirred at a dispersion rate of 60rpm to 100rpm at 40°C to 60°C for 0.5h to 1.5h, and then stirred at a dispersion rate of 80rpm to 120rpm at 20°C to 30°C and vacuum ≤-0.09MPa for 0.5h to 1.5h to obtain the one-component epoxy adhesive.

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