Modified epoxy glue and preparation method thereof

Abstract

The invention discloses a modified epoxy adhesive which is prepared from the following components: epoxy resin, acrylic modified silane polyether resin, polyphenylene sulfide, a curing agent, a catalyst, a nano material and the like. Wherein the acrylic acid modified silane polyether resin is prepared by taking modified silane polyether resin as a matrix and methyl methacrylate, N, N-dimethylaminoethyl methacrylate and maleic anhydride as grafting monomers through an emulsion graft polymerization reaction. The invention also discloses a preparation method of the modified epoxy glue. Compared with the prior art, the invention has the following prominent effects: the interface bonding requirements of different substrates are met, the impact strength exceeds 40MPa, the hardness exceeds D80, the curing time is short, and the harmful substance residue is low.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of adhesives, in particular to a modified epoxy adhesive and a preparation method thereof. BACKGROUND

[0002] With the rapid development of electronic industry, electronic assembly is developing towards lightness, miniaturization and high performance. In order to ensure that the equipment for producing high-precision products is not disturbed by external factors such as vibration, and to realize high-efficiency, stable and reliable operation, the role of the adhesive used is crucial. Precise electronic components may involve the use of various special plastic composite substrates (including ABS, PC, PP, PS, etc.) to achieve special functional goals, and often require adhesives to meet the interface bonding needs of different substrates.

[0003] The existing adhesives with low-temperature rapid curing include UV-cured adhesives, but due to the limitations of curing conditions and color, they cannot meet the needs of most adhesive situations. Another type is epoxy thiol-based adhesives, which can rapidly cure at low temperatures and can be used for bonding various materials with good bonding strength. However, after being cured for a long time in harsh environments, the adhesive strength may decrease significantly.

[0004] With the increasingly deteriorating ecological environment, it is necessary to reduce environmental pollution as much as possible. Therefore, environmental protection is also an important issue that needs to be addressed during the preparation and use of epoxy adhesives. For example, epoxy adhesive products need to have low odor, low volatility, and extremely low release of harmful substances (less than 50 ppm), and other environmental protection features to meet the use requirements of ultra-clean environments. Therefore, the selection of materials for the product is more challenging.

[0005] A Chinese invention patent application with publication number CN 118546639A discloses a low-temperature-resistant and shock-resistant epoxy adhesive and a preparation method thereof. The components include epoxy resin, polyurethane, polyphenylene sulfide, epoxy acrylate resin, curing agent, diluent, coupling agent, promoting agent, and stabilizer. The preparation method steps include: preparing a mixture A of epoxy resin and epoxy acrylate resin; mixing polyurethane and polyphenylene sulfide to obtain a mixture B; adding the mixture A to the mixture B to obtain a mixture C; and adding the curing agent, diluent, coupling agent, promoting agent, and stabilizer, and mixing at high speed to obtain a mixture D; adding the remaining curing agent, diluent, coupling agent, promoting agent, and stabilizer to the mixture D, and vacuum degassing to obtain the shock-resistant epoxy adhesive. The epoxy adhesive obtained by the technical solution has good stability in a low-temperature environment, excellent bonding performance after curing for a long time in a low-temperature environment, and low stress. However, the existing adhesives have the defects of insufficient impact resistance, insufficient hardness, weak weather resistance and adhesive force, and serious VOC volatilization pollution, which cannot meet the needs of the existing market. SUMMARY

[0006] In view of the above-mentioned deficiencies of the prior art, the present application provides a modified epoxy adhesive, which has excellent impact strength and hardness and other mechanical properties, is environmentally friendly and non-toxic, has good stability, and has a short curing time.

[0007] Another object of the present application is to provide a preparation method of the modified epoxy adhesive, which has the advantages of simple process, easy control, and effective performance of the formula system.

[0008] To achieve the above-mentioned objects, the present application is implemented as follows: a modified epoxy adhesive is made from components including the following components by weight: epoxy resin 40-65 acrylic modified silane polyether resin 10~30 polyphenylene sulfide 5-15 curing agent 1-5 diluent 2-10 coupling agent 0.5-5 promoter 0.5-3 thixotropic agent 0.5-3 stabilizer 0.5-2 catalyst 0.5-2 nanomaterial 0.1-0.5

[0009] The acrylic modified silane polyether resin is prepared by emulsion graft polymerization reaction, taking modified silane polyether resin as the parent body, methyl methacrylate, N.N-dimethylaminoethyl methacrylate and maleic anhydride as graft monomers.

[0010] The preparation method of the acrylic modified silane polyether resin includes the following steps: (1) weigh 40~60 parts by weight of methyl methacrylate, 30~50 parts by weight of N.N-dimethylaminoethyl methacrylate and 5~15 parts by weight of maleic anhydride, mix and stir uniformly to prepare a mixed monomer; (2) add modified silane polyether resin and 2-4% of emulsifier based on the total mass of the mixed monomer to a reaction container, the ratio of the total mass of the mixed monomer to the mass of the modified silane polyether resin is 0.3-0.6; dilute with deionized water to a solid content of 20-40%, heat to 50-60℃, uniformly drop the mixed monomer and the oxidizing component of the initiator at a speed of 1-3h, then drop the reducing component of the initiator, keep the reaction for 3-5h, and spray dry until the water content is less than or equal to 0.3%.

[0011] The modified silane polyether resin is ExceStar™ series products (preferably ExceStar™ S3630E) of AGC, Japan, or silane modified polyether resin (MS resin) of Jiangsu Ru Yang Antai New Material Technology Co., Ltd.

[0012] The emulsifier can be selected from one or a combination of sodium methacrylate sulfonate, sodium dodecyl sulfate, dodecyl phenol polyoxyethylene ether, or sodium dodecyl benzene sulfonate.

[0013] The initiator can be one or a combination of benzene hydroperoxide tetraethylene pentamine, t-butyl hydroperoxide-tetraethylene pentamine, ammonium persulfate-sodium bisulfite, etc. redox initiator, preferably benzene hydroperoxide tetraethylene pentamine.

[0014] Secondary initiator (such as ammonium persulfate-sodium bisulfite) can be added in the later stage of the reaction, which can improve the conversion rate to more than 94%.

[0015] The amount of initiator is 0.2% to 0.8% of the modified silane polyether resin, and the mass ratio of the oxidizing component to the reducing component of the initiator is 1.6-2.3:1.

[0016] The curing agent is preferably isophorone diamine, which makes the formulation after curing have good weather resistance and mechanical properties such as hardness.

[0017] The diluent can be trimethylolpropane triglycidyl ether (TMPTGE) and / or polypropylene glycol diglycidyl ether.

[0018] The coupling agent can be one of aminopropyl triethoxysilane (KH-550) and γ-glycidyl ether propyl trimethoxysilane (KH-560).

[0019] The accelerator can be one or a combination of sodium styrene sulfonate, anhydride, 2,4,6-tris(dimethylaminomethyl) phenol, 2-methyl imidazole, which can shorten the gel time, reduce the curing temperature, and improve the physical and chemical properties.

[0020] The thixotropic agent can be one or a combination of organic bentonite or hydrogenated castor oil.

[0021] The stabilizer can be one or a combination of more than two of pentaerythritol, phosphite 168, UV-400, borate, barbituric acid, lauric acid, oxalic acid dihydrazide.

[0022] The catalyst can be one of dibutyltin dilaurate, di-n-octyltin dilaurate, and chelated tin.

[0023] The epoxy resin can be E51 epoxy resin or alicyclic epoxy resin with model numbers Syna-Epoxy 06E and Syna-Epoxy 21 from Nantong Xinnaxi New Materials Co., Ltd.

[0024] The nanomaterial is a combination of one or both of black phosphorus nanosheets and nanosilica.

[0025] Preferably, the nanomaterial is a mixture of black phosphorus nanosheets and nanosilica in a mass ratio of 1:1-3.

[0026] Preferably, the nanosilica is a hydrophobic fumed silica (white carbon black) of the type Aerosil R7200 from Evonik Industries AG, with a particle size of less than 30 nm.

[0027] Preferably, the black phosphorus nanosheets can be black phosphorus nanosheet powder of the type 7723-14-0 from Hefei Keliao New Material Technology Co., Ltd., with a sheet diameter of about 100 nm and a thickness of about 8 layers.

[0028] Preferably, the nanomaterial is a mixture of black phosphorus nanosheets and nanosilica in a mass ratio of 1:2. The addition of the composite nanomaterial can react with the epoxy groups to form strong interfacial bonding, has a synergistic reinforcing effect, and can effectively improve the flame retardation effect, enhance the mechanical properties, and improve the thermal stability.

[0029] A preparation method of a modified epoxy adhesive, comprising the following steps: (1) stirring the epoxy resin and the acrylic-modified silane polyether resin in a diluent at a speed of 100-300 rpm for 1-3 h; (2) adding polyphenylene sulfide and a coupling agent, and continuing to stir at a speed of 200-500 rpm for 2-5 h; (3) adding a curing agent, a promoter, a thixotropic agent, a stabilizer, a catalyst, and a nanomaterial, stirring for 1-3 h first, and then applying ultrasonic treatment while stirring, with a frequency of 30-50 kHz, a power of 80-300 W, and a time of 5-8 h.

[0030] In the third step, the frequency of the ultrasonic treatment is 40 kHz, and the power is 200 W.

[0031] The preparation method described in the present application has a simple process and is easy to control. The ultrasonic and mechanical stirring coupling preparation process not only effectively eliminates bubbles and improves the uniformity of the mixture, but also promotes the close crosslinking between the components and the synergistic formation of an organic whole.

[0032] Compared with the prior art, the present application has the following outstanding effects: meeting the interface bonding requirements of different substrates, impact strength exceeding 40 MPa, hardness exceeding D80, short curing time, and low harmful substance residue. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1A photograph of the sample prepared for Example 4 of the present application. DETAILED DESCRIPTION

[0034] The present application will be further described in conjunction with specific examples. It should be understood that the examples do not limit the scope of the present application.

[0035] The acrylic modified silane polyether resin is prepared by emulsion graft polymerization reaction with modified silane polyether resin as the matrix, methyl methacrylate, N.N-dimethylaminoethyl methacrylate and maleic anhydride as grafting monomers. The specific steps are as follows: (1) 55 parts by weight of methyl methacrylate, 40 parts by weight of N.N-dimethylaminoethyl methacrylate and 10 parts by weight of maleic anhydride are weighed and uniformly mixed to prepare a mixed monomer; (2) ExceStar™ S3630E and 3% of the total mass of the mixed monomer of a emulsifier, dodecyl phenol polyoxyethylene ether, are added to a reaction container. The ratio of the total mass of the mixed monomer to ExceStar™ S3630E is 0.5. Deionized water is added to dilute to a solid content of 30%. After vacuum degassing for 25 min, the temperature is raised to 55°C, and the mixed monomer and initiator oxidizing component, benzene hydroperoxide, are added at a stirring speed of 150 rpm for 2 h. Then the initiator reducing component, tetraethylenepentamine, is added dropwise. The reaction is kept for 4 h, and spray drying is performed until the water content is equal to 0.3%. The product is discharged and stored for use. The amount of the initiator is 0.5% of the weight of the EXCESTAR™ series, and the mass ratio of the oxidizing component to the reducing component of the initiator is 2:1.

[0036] The above EXCESTAR™ series product has an ultra-high molecular weight polyether as the main chain and is terminated by a methoxysilyl group. It has excellent physical and chemical properties. After the above emulsion graft polymerization reaction, the silane polyether resin is modified by introducing acrylic acid. The polar advantage of acrylic acid is combined with the excellent properties of the silane polyether resin matrix to achieve synergistic modification, which effectively improves the weather resistance, heat resistance and mechanical properties. A small amount of maleic anhydride is added. The anhydride group forms a covalent bond with the polyether hydroxyl group, the tertiary amine of N.N-dimethylaminoethyl methacrylate and the epoxy resin, effectively improving the adhesion and hardness after curing, and having excellent low-temperature fast-drying effect. At the same time, it can be well compounded with nano-powder fillers to further improve the heat resistance and mechanical strength.

[0037] Example 1 A modified epoxy adhesive is prepared from components including the following weight fractions: Epoxy resin 41 Acrylic modified silane polyether resin 11 Polyphenylene sulfide 6 Curing agent 1.5 Diluent 3 Coupling agent 0.6 Promoter 0.6 Thixotropic agent 0.7 Stabilizer 0.6 Catalyst 0.6 Nanomaterial 0.2.

[0038] Example 2 A modified epoxy adhesive is made from components including the following parts by weight: Epoxy resin 64 Acryl-modified silane polyether resin 29 Polyphenylene sulfide 14 Curing agent 4 Diluent 9 Coupling agent 4 Promoter 2.5 Thixotropic agent 2.5 Stabilizer 1.5 Catalyst 1.5 Nanomaterial 0.4.

[0039] Example 3 A modified epoxy adhesive is made from components including the following parts by weight: Epoxy resin 55 Acryl-modified silane polyether resin 20 Polyphenylene sulfide 11 Curing agent 3 Diluent 8 Coupling agent 3 Promoter 2 Thixotropic agent 1.8 Stabilizer 1 Catalyst 1 Nanomaterial 0.3.

[0040] A method for preparing the modified epoxy adhesive described above, including the following steps: (1) The epoxy resin and the acryl-modified silane polyether resin are added to the diluent and stirred at a speed of 200 rpm for 5 h; (2) The polyphenylene sulfide and the coupling agent are added, and stirring is continued at a speed of 400 rpm for 3 h; (3) The curing agent, the promoter, the thixotropic agent, the stabilizer, the catalyst, and the nanomaterial are added, first heated to 55°C, stirred at a speed of 300 rpm for 2 h, then cooled to room temperature, and continuously stirred at a speed of 500 rpm while applying ultrasonic treatment for 6 h, with a frequency of 40 kHz and a power of 200 W.

[0041] To verify the technical contribution of the formula components and core process conditions in the technical solution of the present application, the following provides more specific examples and comparative examples, as shown in the table below: Components Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 E51 epoxy resin 55 55 55 55 55 55 Acryl-modified silane polyether resin 20 0 20 20 20 20 Polyphenylene sulfide 11 11 0 11 11 11 Isophorone diamine 3 3 3 3 3 3 Polypropylene glycol diglycidyl ether 8 8 8 8 8 8 KH-560 3 3 3 3 3 3 2,4,6-tris(dimethylaminomethyl)phenol 2 2 2 2 2 2 Hydrogenated castor oil 1.8 1.8 1.8 1.8 1.8 1.8 Oxalic acid dihydrazide 1 1 1 1 1 1 Di-n-octyltin dilaurate 1 1 1 1 1 0 7723-14-0 0.1 0.1 0.1 0 0 0.1 Aerosil R7200 0.2 0.2 0.2 0 0.2 0.2 The preparation method of the above examples and comparative examples is as described above, and the sample prepared in Example 4 is in the form of a paste, as shown in Figure 1 Comparative Example 6 is consistent with the formula of Example 4, but no ultrasonic treatment is applied during preparation.

[0042] Performance test 1. Adhesion performance

[0043] A universal mechanical testing machine CMT5105 was used for the test. The substrate plate was an aluminum alloy plate with a size of 100 mm x 25 mm x 1.6 mm. The bonding area of the substrate plate was polished uniformly along the 0° direction using 180-mesh sandpaper, and the bonding area size was 25 mm x 25 mm x 1 mm. The dirt on the polished area was wiped off with acetone and dried. After the substrate plates were bonded together using the sample prepared in the above examples and comparative examples, the fixture was clamped at 60°C for 1 h. After cooling for 1 d, the bending strength of the bonded substrate plates was tested, with a bending rate of 2 mm / min. Five repetitions were performed for each group, and the average value was taken.

[0044] Sample Adhesion strength (MPa) Example 4 11.12 Comparative Example 1 6.68 Comparative Example 2 8.36 Comparative Example 3 6.27 Comparative Example 4 8.45 Comparative Example 5 7.33 Comparative Example 6 9.34 As can be seen from the above table, Example 4 has the best bonding effect, proving that Example 4 is the best example and has excellent adhesion performance. On the contrary, Comparative Example 6 has much poorer adhesion performance because no ultrasonic treatment is applied. Therefore, the preparation process of ultrasonic and mechanical stirring coupling treatment makes the resin and the nanomaterial more uniformly mixed and activated due to the ultrasonic effect, with higher viscosity and more excellent mechanical properties.

[0045] 2. Weather resistance The sample prepared in Example 4 was coated on the plate surface after curing and heated to 110°C for 2 h as a control group compared with a commercially available water-based PU glue. The PU glue of the control group foamed, and the modified epoxy glue coated with Example 4 had no difference before heating, indicating that the modified epoxy glue described in the present application has excellent heat resistance.

[0046] 3. Light resistance Light resistance test: the sample prepared by the epoxy adhesive of Example 4 and the sample prepared by the commercially available waterborne PU adhesive were placed in a simulated sunlight irradiation environment, and observed after irradiation with 340 nm light for 1000 h. The PU adhesive of the control group showed obvious yellowing and brittleness, while the sample prepared by the modified epoxy adhesive of the application showed no obvious change in appearance. The test results show that the modified epoxy adhesive of the application has good light resistance and can maintain extremely stable performance in outdoor light environment.

[0047] 4. Mechanical property test 4.1 Determination of impact strength

[0048] The impact strength was tested on a pendulum impact tester according to the standard of “GB / T 6328-2021 Adhesives - Determination of shear impact strength”. The pendulum speed was 3.4 m / s.

[0049] 4.2 Determination of compressive strength The test was carried out on a universal mechanical testing machine CMT5105 according to the standard of “GB / T 7124-2008 Determination of tensile shear strength of adhesives (rigid material to rigid material)”. The epoxy adhesive was cut into a cylinder with a diameter of 12.7 mm and a height of 25.4 mm after curing, ensuring that the upper and lower ends were smooth and parallel to each other. The compression rate was 2 mm / min, and the sample was continuously compressed until it was damaged, and the load reached the maximum value.

[0050] 4.3 Shore D hardness The test was carried out according to the standard of “GB / T 2411-2008 Plastics and ebonite - Determination of indentation hardness by use of a hardness tester (Shore hardness)”. The sample thickness was 6 mm.

[0051] Impact strength (KJ / m2) Compressive strength (MPa) Shore D hardness Example 4 42.16 25.58 82 Comparative Example 1 21.2 12.43 56 Comparative Example 2 36.38 21.25 73 Comparative Example 3 25.79 21.42 61 Comparative Example 4 36.36 17.57 72 Comparative Example 5 31.98 20.21 64 Comparative Example 6 38.89 23.38 75 The impact strength of the sample prepared in Example 4 was more than 40 KJ / m², and the Shore D hardness was also more than 80, which had obvious advantages over the sample of Comparative Example 6 prepared without ultrasonic and mechanical stirring coupling treatment and other comparative samples. As can be seen from the above table, the ultrasonic and mechanical stirring coupling preparation process not only eliminates bubbles and improves the uniformity of the mixture, but also promotes the close crosslinking between the components, and the components form an organic whole, which plays an indispensable excellent effect.

[0052] 5. Harmful substance residue test The sample prepared in Example 4 was detected by ion chromatography, and the results are shown in the following table:

[0054] As can be seen from the above table, the sample has no main harmful component residue.

[0055] The sample prepared in Example 4 was detected according to the method of GB / T 18883-2022 "Indoor air quality standard", and the total volatile organic compounds were 31 μg / m 3 , far lower than the lower limit of the standard 50 μg / m 3 , proving that the sample prepared by the application has excellent safety and environmental protection.

[0056] The above is only a preferred embodiment of the present application, and cannot limit the scope of the present application, that is, any simple equivalent changes and modifications made according to the scope of the patent application and the content of the invention description are still within the scope of the present application.

Claims

1. A modified epoxy adhesive, characterized in that, It is made from the following components in parts by weight: Epoxy resin 40-65 Acrylic modified silane polyether resin 10~30 Polyphenylene sulfide 5-15 Hardener 1-5 Diluent 2-10 Coupling agent 0.5-5 Mutagen 0.5-3 Thixotropic agent 0.5-3 Stabilizer 0.5-2 Catalyst 0.5-2 Nanomaterials 0.1-0.

5.

2. The modified epoxy adhesive according to claim 1, characterized in that, The acrylic-modified silane polyether resin is prepared by emulsion graft polymerization using modified silane polyether resin as the parent material and methyl methacrylate, N,N-dimethylaminoethyl methacrylate and maleic anhydride as graft monomers.

3. The modified epoxy adhesive according to claim 2, characterized in that, The preparation method of the acrylic-modified silane polyether resin includes the following steps: (1) Weigh 40-60 parts by weight of methyl methacrylate, 30-50 parts by weight of N,N-dimethylaminoethyl methacrylate, and 5-15 parts by weight of maleic anhydride, and stir and mix them evenly to prepare a mixed monomer; (2) Add modified silane polyether resin and emulsifier accounting for 2-4% of the total mass of the mixed monomers to the reaction vessel. The ratio of the total mass of the mixed monomers to the mass of the modified silane polyether resin is 0.3-0.

6. Add deionized water to dilute to a solid content of 20-40%, heat to 50-60℃, and uniformly add the oxidizing component of the mixed monomers and initiator over 1-3 hours. Then add the reducing component of the initiator, keep the reaction at the temperature for 3-5 hours, and spray dry until the moisture content is less than or equal to 0.3%.

4. The modified epoxy adhesive according to claim 3, characterized in that, The modified silane polyether resin is the ExceStar™ series product of Asahi Glass Co., Ltd. of Japan or the silane modified polyether resin of Jiangsu Ruiyang Antai New Material Technology Co., Ltd.; the emulsifier is one or a combination of two of sodium methacrylate sulfonate, sodium dodecyl sulfate, dodecylphenol polyoxyethylene ether, or sodium dodecylbenzene sulfonate; the initiator is one or a combination of two of redox initiators such as cumene hydroperoxide-tetraethylenepentamine, tert-butyl hydroperoxide-tetraethylenepentamine, and ammonium persulfate-sodium bisulfite, the amount of the initiator is 0.2% to 0.8% of the modified silane polyether resin, and the mass ratio of the oxidizing component to the reducing component of the initiator is 1.6-2.3:

1.

5. The modified epoxy adhesive according to claim 1, characterized in that, The curing agent is isophorone diamine; the diluent is trimethylolpropane triglycidyl ether and / or polypropylene glycol diglycidyl ether; the coupling agent is one of aminopropyltriethoxysilane and γ-glycidyl etheroxypropyltrimethoxysilane; the mutagen is one or a combination of two of sodium styrene sulfonate, acid anhydride, 2,4,6-tris(dimethylaminomethyl)phenol, and 2-methylimidazole; the thixotropic agent is one or a combination of two of organobentonite and hydrogenated castor oil; the stabilizer is one or a combination of two or more of pentaerythritol, phosphite 168, UV-400, borate ester, barbituric acid, lauric acid, and dioxohydrazide; and the catalyst is one of dibutyltin dilaurate, dioctyltin dilaurate, and chelated tin.

6. The modified epoxy adhesive according to claim 1, characterized in that, The epoxy resin is E51 epoxy resin or alicyclic epoxy resins of Nantong Xinnaxi New Materials Co., Ltd., with the model numbers Syna-Epoxy 06E ​​and Syna-Epoxy 21.

7. The modified epoxy adhesive according to claim 1, characterized in that, The nanomaterial is one or a combination of black phosphorus nanosheets and nano-silica.

8. The modified epoxy adhesive according to claim 7, characterized in that, The nanomaterial is a combination of black phosphorus nanosheets and nano-silica in a mass ratio of 1:1-3.

9. A method for preparing a modified epoxy adhesive according to any one of claims 1-8, characterized in that, Includes the following steps: (1) Add epoxy resin and acrylic modified silane polyether resin to the diluent and stir at 100-300 rpm for 1-3 hours; (2) Add polyphenylene sulfide and coupling agent, and continue stirring at a speed of 200-500 rpm for 2-5 hours; (3) Add curing agent, mutagen, thixotropic agent, stabilizer, catalyst and nanomaterials, stir for 1-3 h, and then apply ultrasonic treatment while stirring. The ultrasonic frequency is 30-50 kHz, the power is 80-300 W, and the time is 5-8 h.

10. The method for preparing a modified epoxy adhesive according to claim 9, characterized in that, In step (3), the frequency of the ultrasonic treatment is 40 kHz and the power is 200 W.

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