Interpenetrating network polymer as well as preparation method and application thereof

Abstract

The invention relates to the technical field of preparation of interpenetrating network polymers, in particular to an interpenetrating network polymer as well as a preparation method and application thereof. The interpenetrating network polymer is prepared by initiating a front-end polymerization reaction of epoxy resin and acrylate. The polymer not only can give consideration to key mechanical properties such as tensile strength, impact strength, bending strength and flexural modulus at the same time, realizes collaborative optimization of high strength, high toughness and high rigidity, but also remarkably improves the processing fluidity of a raw material system. Besides, the preparation process only needs to be triggered instantly, and the adhesive has the advantages of high curing speed and low energy consumption, and is suitable for application requirements in the fields of electronic component packaging and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of interpenetrating polymer network preparation, in particular to an interpenetrating polymer network, a preparation method and application thereof. BACKGROUND

[0002] It is well known that epoxy resin is a kind of thermosetting material, which is widely used in many fields such as coatings, adhesives, high-performance composites and electronic packaging due to its excellent properties such as high mechanical properties, low shrinkage and excellent chemical stability. However, due to the characteristics of high crosslinking degree of epoxy resin, its toughness is low, which is easy to cause damage under low load, which limits its application in fields requiring high strength, high toughness and high stiffness. At present, various methods have been developed to endow epoxy resin system with high toughness, high strength and other excellent comprehensive properties. For example, people use rubber, thermoplastic polymer materials, long-chain macromolecular curing agents and other technical means to improve the toughness of epoxy resin materials. But these methods often have to give up something to get something, while improving toughness, they reduce the strength and temperature resistance. Interpenetrating polymer network (IPN) as a new technical means, the second phase toughening component can interpenetrate and entangle with the crosslinked network of epoxy resin, so that the components can coexist stably and synergistically, so as to realize the mutual balance of performance to a certain extent, and effectively overcome the shortcomings of traditional methods.

[0003] Generally, according to the difference between stepwise curing and simultaneous curing process, interpenetrating polymer structure can be divided into sequential interpenetrating network (sequential IPNs) and simultaneous interpenetrating network (simultaneous IPNs). In sequential interpenetrating network, the crosslinking reaction of the second network is limited by the previously formed first network structure, resulting in more obvious two-phase interface and higher degree of phase separation; while in simultaneous interpenetrating network, the crosslinking of two network polymers is carried out simultaneously and independently, and the interpenetration of molecular chains is more close, so as to effectively inhibit the phase separation phenomenon. However, the traditional simultaneous curing interpenetrating network polymer is realized in the same temperature thermal environment, due to the inconsistency of the reaction activity and the reaction degree of the two polymer systems, macro-scale phase separation is easy to occur. The existence of this macro-phase separation will lead to the decline of the mechanical, thermal, optical and other properties of the interpenetrating network polymer, and the mechanical strength and fracture toughness often exist mutual exclusion phenomenon, which is difficult to achieve. For example, Luo et al. (Effects of curing temperature on the structure and properties of epoxy resin-poly(ε-caprolactam) blends, Polymer 228 (2021) 123940) studied the toughening effect of semi-interpenetrating network polymer formed by blending poly(ε-caprolactam) and bisphenol A type epoxy resin-diethylene triamine system (DGEBA-DETA) on the epoxy system. When the addition amount of poly(ε-caprolactam) is 15wt%, the impact toughness increases from 12.5 kJ / m 2 to 24.4 kJ / m 2 , but due to the existence of obvious phase separation in the mixed system, the tensile strength decreases from 62.8 MPa to 39.1 MPa, and the bending strength decreases from 126.0 MPa to 89.0 MPa, which cannot simultaneously achieve high strength, high toughness and high stiffness of the material.

[0004] Frontal polymerization (FP) is a solidification method that converts monomers into polymers through a local reaction zone and maintains the reaction by using the heat of polymerization. This method can achieve rapid curing of high exothermic monomers (such as dicyclopentadiene, epoxy resin, etc.) with extremely low external energy input. With the advantages of rapid curing and high energy efficiency, frontal polymerization provides a new idea for the efficient preparation of high-performance epoxy resins and their composites. For monomer types that can undergo frontal polymerization, dicyclopentadiene cured products are highly valued due to their high flexibility and few crosslinking points. For example, Chinese Patent Application CN118027607A discloses a photo-initiated epoxy resin-polycyclopentadiene interpenetrating network polymer. Although this polymer has excellent properties such as high toughness and high strength, the viscosity of the mixed solution before polymerization is high, which restricts the processing flowability of the raw material system. Moreover, the flexural modulus of the polymer after polymerization decreases with increasing dicyclopentadiene content, which cannot simultaneously achieve the synergistic optimization of high strength, high toughness, and high stiffness of the material. SUMMARY

[0005] The technical problem to be solved by the present application is to overcome the defects and deficiencies in the prior art that interpenetrating network polymers cannot simultaneously achieve the synergistic optimization of high strength, high toughness, and high stiffness of the material, and the processing flowability of the raw material system is poor. The present application provides a preparation method of an interpenetrating network polymer.

[0006] Another object of the present application is to provide an interpenetrating network polymer prepared by the above preparation method.

[0007] Still another object of the present application is to provide the application of the above interpenetrating network polymer in the field of electronic device packaging.

[0008] The above objects of the present application are achieved by the following technical solutions: The present application protects a preparation method of an interpenetrating network polymer, comprising the following steps: S1. Mixing epoxy resin monomers, acrylic ester monomers, cationic initiators, first radical initiators, and second radical initiators to obtain an epoxy resin-acrylic ester mixed solution; S2. Transferring the epoxy resin-acrylic ester mixed solution obtained in step S1 into a mold, defoaming, and initiating frontal polymerization to obtain an interpenetrating network polymer; The molar ratio of the epoxy resin monomers, the cationic initiators, and the first radical initiators is 1: (0.01-0.02): (0.01-0.02); The molar ratio of the acrylic ester monomers and the second radical initiators is 1: (0.01-0.02); The mass ratio of the epoxy resin monomer and the acrylate monomer is 1: (0.01-0.30).

[0009] In view of the problem that the interpenetrating network polymer in the prior art cannot simultaneously balance high strength, high toughness and high stiffness of the material, and the processing fluidity of the raw material system is poor. The application introduces acrylate and epoxy resin to construct an interpenetrating network polymer, and realizes the synergistic optimization of the mechanical properties and the processing fluidity of the raw material system. Experimental data show that: on the one hand, with the addition of acrylate, the viscosity of the epoxy resin-acrylate mixed solution is significantly reduced, and the processing fluidity is effectively improved; on the other hand, the interpenetrating network polymer structure not only significantly improves the toughness of the pure epoxy resin system, but also synchronously improves the strength and stiffness of the material by introducing acrylate. In summary, the interpenetrating network polymer of the application can not only balance high strength, high toughness and high stiffness, but also significantly improve the processing fluidity of the raw material system, providing key technical support for the application of epoxy resin in high requirement scenarios.

[0010] Further, the epoxy resin monomer includes one or more of bisphenol A diglycidyl ether, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexyl carboxylate, 1,6-hexanediol diglycidyl ether, and neopentyl glycol diglycidyl ether.

[0011] Further, the acrylate monomer includes one or more of trimethylolpropane triacrylate, polyethylene glycol diacrylate, and pentaerythritol triacrylate.

[0012] Preferably, the mass ratio of the epoxy resin monomer and the acrylate monomer is 1: (0.03-0.25).

[0013] More preferably, the mass ratio of the epoxy resin monomer and the acrylate monomer is 1: (0.05-0.20).

[0014] Further, the cationic initiator includes one or more of 4-octyloxydiphenyliodonium hexafluoroantimonate, bis[4-(tert-butyl)phenyl] iodonium tetrakis(nonafluoro-t-butoxy)aluminate, and diphenyliodonium hexafluorophosphate.

[0015] Further, the first radical initiator and the second radical initiator are each independently selected from one or more of benzopinacol, dibenzoyl peroxide, and 1,1-di-tert-butylperoxy-3,3,5-trimethylcyclohexane. That is, the first radical initiator and the second radical initiator can be the same or different.

[0016] Preferably, the mixing is stirring mixing.

[0017] Preferably, the mixing temperature is 25-70°C.

[0018] Preferably, the mixing time is 2-6 h.

[0019] Preferably, the mold is a silica gel mold so as to be subsequently demolded.

[0020] Preferably, the defoaming is vacuum defoaming.

[0021] Preferably, the defoaming time is 20-40 min.

[0022] Further, the front-end polymerization is photo-initiated or heat-initiated.

[0023] Still further, the front-end polymerization is to initiate the polymerization reaction under the condition of a light source or a heat source, remove the light source or the heat source, and the polymerization reaction relies on the heat released by itself to diffuse to the unreacted area until all raw materials in the entire reactor are completely converted into solids, i.e., an interpenetrating network polymer is formed.

[0024] Specifically, the photo-initiated front-end polymerization process is as follows: the leftmost epoxy resin-acrylate mixed solution in the mold is placed below a light source, the distance between the solution and the light source is kept at 5-10 mm, when it is observed that the solution is converted from liquid to solid and gradually advances from the left end to the right end, the light source is removed, and the polymerization reaction will continue to advance relying on the heat released by the reaction itself, constantly consuming the unreacted monomers in the mixed solution, until all monomers are completely reacted (the liquid resin is completely solidified into solids), and finally an intact interpenetrating network polymer is formed.

[0025] Further, the wavelength of the photo-initiation is 365-405 nm.

[0026] Preferably, the photo-initiation mode is laser probe initiation or ultraviolet lamp initiation.

[0027] More preferably, the wattage of the laser probe is 10-14 W.

[0028] Specifically, the heat-initiated front-end polymerization process is as follows: a heat source is placed at the leftmost epoxy resin-acrylate mixed solution in the mold, the distance between the solution and the heat source is kept at 5-10 mm, when it is observed that the solution is converted from liquid to solid and gradually advances from the left end to the right end, the heat source is removed, and the polymerization reaction will continue to advance relying on the heat released by the reaction itself, constantly consuming the unreacted monomers in the mixed solution, until all monomers are completely reacted (the liquid resin is completely solidified into solids), and finally an intact interpenetrating network polymer is formed.

[0029] Further, the temperature of the heat initiation is 250-350 ℃.

[0030] Preferably, the heat initiation mode includes electric iron heat initiation, microwave heating initiation, or magnetic heat initiation.

[0031] Further, the initiation time of the front-end polymerization is 10-30 s.

[0032] The present application protects the interpenetrating network polymer prepared by the aforementioned preparation method.

[0033] The present application protects the application of the aforementioned interpenetrating network polymer in the field of electronic component packaging.

[0034] Compared with the prior art, the present application has the following beneficial effects: The present application prepares an interpenetrating network polymer by initiating the front-end polymerization reaction of epoxy resin and acrylate. The polymer not only can simultaneously consider the key mechanical properties such as tensile strength, impact strength, bending strength and bending modulus, realizes the synergistic optimization of high strength, high toughness and high stiffness, but also significantly improves the processing fluidity of the raw material system. In addition, its preparation process only needs to be initiated instantaneously, has the advantages of fast curing speed and low energy consumption, and is suitable for the application requirements in the field of electronic component packaging. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 The polymerization mechanism diagram when the epoxy resin system and the acrylate system in Example 1 are respectively subjected to front-end polymerization.

[0036] Figure 2 The infrared spectra of the epoxy resin solution and the acrylate solution in Example 1 before and after the front-end polymerization reaction; in the figure, “FP-DT” represents the interpenetrating network polymer D95T5 after front-end polymerization, “Liquid-DT” represents the epoxy resin-acrylate mixed solution before front-end polymerization, “TMPTA” represents the acrylate monomer, and “DEGBA” represents the epoxy resin monomer.

[0037] Figure 3 The cross-section SEM diagram of the network polymer in Examples 1-4 and Comparative Example 1.

[0038] Figure 4 The cross-section SEM diagram of the interpenetrating network polymer in Comparative Example 5.

[0039] Figure 5 The glass transition diagram of the network polymer in Examples 1-4 and Comparative Example 1.

[0040] Figure 6 The viscosity change diagram of the epoxy resin solution or the epoxy resin-acrylate mixed solution in Examples 1-4 and Comparative Example 1. DETAILED DESCRIPTION

[0041] The present application is further described in conjunction with the accompanying drawings and specific examples, but the examples do not limit the present application in any form. Unless otherwise specified, the reagents, methods and equipment used in the present application are conventional reagents, methods and equipment in the art.

[0042] Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0043] Figure 1 (a) represents Figure 1 the (a) graph in FIG. 1, Figure 1 (b) represents Figure 1 the (b) graph in FIG. 1.

[0044] Example 1 Preparation of an interpenetrating network polymer S1. 100.0 g of bisphenol A diglycidyl ether (293.7 mmol), 5.26 g of trimethylolpropane triacrylate (17.7 mmol), 1.98 g of 4-octyloxydiphenyl iodonium hexafluoroantimonate (2.938 mmol), and 0.78 g of benzopinacol (3.206 mmol) were placed in an oil bath at 50 °C for magnetic stirring for 3 h to obtain a mixed solution in a light yellow transparent state, i.e., an epoxy-acrylate mixed solution, which was then placed in a defoaming barrel for 30 min to remove bubbles. The defoamed epoxy-acrylate mixed solution was transferred to a silica gel mold (100.0 x 5.0 x 4.0 mm 3 ); S2. The temperature of the electric iron was adjusted to 300 °C, and the tip of the electric iron was placed at the left end of the epoxy-acrylate solution in the mold to initiate heating. The distance between the solution and the tip was maintained at 8 mm. When it was observed that the solution changed from a liquid state to a solid state and gradually advanced from the left end to the right end, the electric iron was removed (irradiation for about 20 s). The polymerization reaction continued to advance relying on the heat released by the reaction itself, continuously consuming the unreacted monomers in the mixed solution, until all the monomers were consumed (i.e., the liquid resin was completely solidified into a solid), and a complete epoxy-acrylate interpenetrating network polymer D95T5 (where D is the abbreviation of epoxy resin DGEBA, T is the abbreviation of trimethylolpropane triacrylate TMPTA, and 95 / 5 is the mass ratio of the two) was obtained.

[0045] Experimental Example 2 Preparation of an interpenetrating network polymer The difference from Example 1 is that in step S1, the mass ratio of epoxy resin monomers to acrylate monomers is changed from 95:5 to 90:10; and in step S2, an epoxy-acrylate interpenetrating network polymer D90T10 is obtained.

[0046] The other steps and conditions remain the same as in Example 1.

[0047] Example 3 Preparation of an interpenetrating network polymer The difference from Example 1 is that in step S1, the mass ratio of epoxy resin monomer to acrylate monomer is changed from 95:5 to 85:15; in step S2, an epoxy resin-acrylate interpenetrating network polymer D85T15 is obtained.

[0048] Other steps and conditions remain the same as in Example 1.

[0049] Example 4 Preparation of an interpenetrating network polymer The difference from Example 1 is that in step S1, the mass ratio of epoxy resin monomer to acrylate monomer is changed from 95:5 to 80:20; in step S2, an epoxy resin-acrylate interpenetrating network polymer D80T20 is obtained.

[0050] Other steps and conditions remain the same as in Example 1.

[0051] Comparative Example 1 Preparation of a network polymer The difference from Example 1 is that in step S1, the acrylate monomer is replaced with an equal amount of epoxy resin monomer, i.e., the mass ratio of epoxy resin monomer to acrylate monomer is 100:0; in step S2, an epoxy resin single network D100T0 is obtained.

[0052] Other steps and conditions remain the same as in Example 1.

[0053] Comparative Example 2 Preparation of a network polymer The difference from Example 1 is that in step S1, the epoxy resin monomer is replaced with an equal amount of acrylate monomer, i.e., the mass ratio of epoxy resin monomer to acrylate monomer is 0:100; in step S2, an acrylate single network D0T100 is obtained.

[0054] Other steps and conditions remain the same as in Example 1.

[0055] The experimental results show that this comparative example failed to successfully form a shaped network polymer due to the excessive brittleness of the material during the front-end polymerization process, as a pure acrylate system was used. Therefore, no performance testing was conducted on it.

[0056] Comparative Example 3 Preparation of an interpenetrating network polymer The difference from Example 1 is that in step S2, the curing method is changed from front-end polymerization to overall heating and gradual temperature increase. The specific steps are as follows: heating to 80 °C for 2 h, heating to 100 °C for 4 h, heating to 120 °C for 4 h, heating to 135 °C for 2 h, and naturally cooling to room temperature.

[0057] Other steps, conditions and example 1 remain unchanged.

[0058] Preparation of an interpenetrating network polymer The difference from example 1 is that in step S1, the molar ratio of bisphenol A diglycidyl ether, 4-octyloxydiphenyl iodonium hexafluoroantimonate, benzopinacol is adjusted to 100:0.75:0.75.

[0059] Other steps, conditions and example 1 remain unchanged.

[0060] The experimental results show that this comparative example cannot initiate polymerization after being initiated by ultraviolet light or electric iron due to insufficient amount of initiator, and thus fails to successfully form an interpenetrating network polymer, so subsequent performance testing is not performed.

[0061] Preparation of an interpenetrating network polymer The difference from example 1 is that in step S1, the molar ratio of bisphenol A diglycidyl ether, 4-octyloxydiphenyl iodonium hexafluoroantimonate, benzopinacol is adjusted to 100:2.5:2.5.

[0062] Other steps, conditions and example 1 remain unchanged.

[0063] The experimental results show that due to excessive amount of initiator, the front-end polymerization process is too violent, and high temperature leads to boiling, carbonization and depolymerization of monomers, so that the cured sample presents brown-black color and is full of holes inside (see Figure 4 ), and such porous structure will significantly destroy the structural integrity of the material, so subsequent performance testing is not performed.

[0064] Experimental example 1 Polymerization principle and composition characterization of network polymer 1. Polymerization principle of interpenetrating network polymer The polymerization of interpenetrating network polymer is divided into epoxy resin front-end polymerization and acrylate front-end polymerization (see Figure 1 ), and the polymerization mechanism is as follows: (1) Epoxy resin front-end polymerization mechanism (see Figure 1 (a)): free radical initiator is decomposed by heat to produce free radicals; free radicals split cationic initiator to produce cations; cations take protons to form strong acids (Photo-acid generator, PAG); strong acids initiate monomer polymerization and release a large amount of heat; the generated heat again decomposes the remaining free radical initiator to produce free radicals, which repeatedly circulate to complete polymerization.

[0065] (2) Acrylate front-end polymerization mechanism (see Figure 1(b)): The free radical initiator decomposes under heat to produce free radicals; the free radicals induce the acrylate monomer to form monomer free radicals; the monomer free radicals undergo chain growth with another monomer and release heat; the generated heat again causes the remaining free radical initiator to decompose and produce free radicals, and the cycle is repeated to complete the polymerization.

[0066] 2. Infrared spectroscopy characterization The molecular structure of the epoxy resin-acrylate mixed solution in Example 1 before and after the front-end polymerization reaction was characterized at room temperature using a Nexus 670 infrared system from Thermo Nicolet. The results are shown in FIG. Figure 2 As shown, 1720 cm -1 and 1640cm -1 The absorption peaks at 911 cm-1 correspond to the carbonyl and carbon-carbon double bond stretching vibration peaks in the acrylate monomer. -1 The absorption peak is the three-membered ring vibration peak of the epoxy group in the epoxy monomer. After the front end polymerization, 1640 cm -1 The double bond peak at 911 cm -1 The epoxy peaks at the positions disappeared, indicating that free radical polymerization occurred on the double bonds of acrylates, and the epoxy groups of epoxy resin participated in cross-linking through ring-opening reaction, forming an epoxy resin-acrylate interpenetrating network polymer structure.

[0067] 3. Scanning Electron Microscope Characterization The cross-sectional micromorphology of the network polymers prepared by front-end polymerization in Examples 1 to 4 and Comparative Example 1 was observed using a Hitachi S-4800 cold field emission scanning electron microscope. Figure 3 As shown in the figure, the SEM images of the tensile cross-section of the material show that the cross-section of pure epoxy D100T0 is smooth and flat, with a single crack direction and no stress dispersion or yielding, exhibiting typical brittle fracture characteristics. However, after the introduction of a certain amount of TMPTA, the roughness of the material cross-section increased significantly, and no phase separation was observed, indicating good compatibility of the system. Furthermore, the cross-section of the D85T15 sample exhibited dense grooves. The increased surface roughness indicates an increase in crack density, which allows the material to absorb more fracture energy, thereby significantly improving its mechanical properties, especially toughness.

[0068] 4. Characterization of Glass Transition Temperature (1) Test method The glass transition temperature (Tg) of the network polymers in Examples 1-4 and Comparative Example 1 was measured using a PerkinElmer DSC6000 Differential Scanning Calorimeter (USA). The DSC test procedure was set to a "heating-cooling-heating" cycle within the range of 25-250°C at a heating / cooling rate of 10°C / min. The first heating step was used to eliminate the thermal history of the material, and the glass transition temperature (Tg) was determined by the "step-shift" heat flow curve during the second heating step. Furthermore, the first heating curve can be used to characterize the degree of post-curing of the material.

[0069] (2) Experimental results The results are as follows Figure 5 As shown, DSC testing reveals that the heat flow curves of the pure epoxy resin single network polymer in Comparative Example 1 and the interpenetrating network polymers of Examples 1-4 each exhibit only a single significant inflection point, corresponding to a single glass transition temperature (Tg). The temperature corresponding to this inflection point is the Tg value of the material. The data also show that with increasing TMPTA dosage, the Tg values ​​of each system remain similar, with no significant change. This demonstrates the good compatibility of epoxy resin and acrylate in the interpenetrating network structure. Furthermore, the synergistic crosslinking effect of the interpenetrating network effectively maintains the thermal stability of the system, providing experimental support for design modifications that balance material toughness and heat resistance.

[0070] 5. Solution Viscosity Characterization (1) Test method Steady-state viscosity tests were conducted using a Thermo Fisher Scientific MARS40 rotational rheometer. The test procedure was as follows: at a fixed temperature of 25°C, the average viscosity of the pure epoxy resin solution or epoxy resin-acrylate mixed solution in Comparative Example 1 and Examples 1-4 was measured over a constant time (2 minutes).

[0071] (2) Experimental results The results are as follows Figure 6 As shown in the figure, as the TMPTA content increases, the solution viscosity shows a significant downward trend. The reduction in viscosity directly improves the fluidity of the solution, facilitating subsequent processing techniques such as coating, infusion, and molding.

[0072] Experimental Example 2 Mechanical Properties Test of Network Polymer 1. Experimental Methods (1) Tensile Strength: The network polymers of Examples 1-4 and Comparative Example 1 and Comparative Example 3 were tested using a universal mechanical testing machine from Shanghai Lishi Scientific Instrument Co., Ltd. in accordance with ASTM D-638-2022. Tensile strength indicates a material's ability to resist axial tensile stress (breaking). High tensile strength indicates good material strength.

[0073] (2) Bending strength / modulus: The network polymers of Examples 1-4, Comparative Example 1 and Comparative Example 3 were tested by a universal mechanical testing machine of Shanghai Lisen Scientific Instrument Co., Ltd., and the test standard was ASTM D-790-2017. The bending strength and bending modulus represent the ability of the material to resist bending load (not easy to break, plastic deformation or elastic deformation when bending). High bending strength and high bending modulus indicate that the material has strong resistance to bending deformation, i.e., the material has high stiffness.

[0074] (3) Impact strength: The impact performance of the network polymers of Examples 1-4, Comparative Example 1 and Comparative Example 3 was tested by a pendulum impact testing machine (ZwickRoell, HIT25P), and the test standard was ASTM D256-2010. The impact strength represents the ability of the material to absorb instantaneous impact energy (such as impact, drop) without breaking. High impact strength indicates that the material has good toughness.

[0075] 2. Experimental results Table 1 Mechanical property data of network polymers

[0076] As can be seen from Table 1, by adjusting the ratio of acrylate and epoxy resin in Examples 1-4, a uniform interpenetrating network structure is formed, and the materials exhibit high strength, high toughness and high stiffness: the tensile strength is ≥57.49±5.97 MPa, the impact strength is ≥1.78±0.11 kJ / m 2 , the bending strength is ≥106.23±11.55 MPa, and the bending modulus is ≥2951.05±115.32 MPa. Among them, although the overall performance of Example 4 is slightly lower than that of Example 1, it still maintains a high level and is significantly better than the comparative example systems. The results show that acrylate can achieve synergistic optimization of high strength, high toughness and high stiffness under moderate ratio.

[0077] In contrast, the mechanical properties of Comparative Example 1 cannot be effectively improved because acrylate and epoxy resin are not introduced for crosslinking, and the impact strength, bending strength and bending modulus are poor. In contrast, in the interpenetrating network polymers of Examples 1-4 of the present application, with the addition of acrylate, the impact strength, bending strength, bending modulus and tensile strength of the material are significantly improved, effectively solving the problem that the interpenetrating network polymers in the prior art cannot simultaneously have high strength, high toughness and high stiffness. Although Comparative Example 3 prepared an interpenetrating network polymer by overall heating and gradual temperature rise curing, the impact strength was improved compared with the single network of epoxy resin, but the toughness improvement effect was significantly weaker than the simultaneous interpenetrating network prepared by local initiation front polymerization, and the bending modulus and tensile strength decreased due to the macroscopic phase separation problem.

[0078] In summary, the present application prepares an interpenetrating network polymer with uniform structure and no phase separation by initiating a front polymerization reaction of epoxy resin and acrylate, which can simultaneously have high strength, high toughness and high stiffness mechanical properties and excellent raw material system processing fluidity. The preparation process only needs to be initiated instantaneously, has the characteristics of fast curing speed and low energy consumption, and is suitable for high-tech fields such as electronic device packaging.

[0079] The above embodiments are preferred embodiments of the present application, but the embodiments of the present application are not limited to the above embodiments, and any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the present application should be equivalent replacement methods, and are all included in the protection scope of the present application.

Claims

1. A method for preparing an interpenetrating polymer network, characterized in that: The steps include: S1. The epoxy resin monomer, the acrylate monomer, the cationic initiator, the first free radical initiator and the second free radical initiator are mixed to obtain an epoxy resin - acrylate mixed solution; S2. The epoxy resin-acrylate mixed solution obtained in step S1 is transferred to a mold, defoamed, and the front end polymerization is initiated to obtain an interpenetrating polymer network; Wherein, the molar ratio of the epoxy resin monomer, the cationic initiator and the first free radical initiator is 1: (0.01-0.02): (0.01-0.02); The molar ratio of the acrylate monomer to the second free radical initiator is 1:(0.01-0.02); The mass ratio of the epoxy resin monomer to the acrylate monomer is 1:(0.01-0.30).

2. The preparation method according to claim 1, characterized in that The acrylate monomer includes one or more of trimethylolpropane triacrylate, polyethylene glycol diacrylate, and pentaerythritol triacrylate.

3. The preparation method according to claim 1, characterized in that: The epoxy resin monomer includes one or more of bisphenol A diglycidyl ether, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexylcarboxylate, 1,6-hexanediol diglycidyl ether, and neopentyl glycol diglycidyl ether.

4. The preparation method according to claim 1, characterized in that The cationic initiator includes one or more of 4-octyloxydiphenyliodonium hexafluoroantimonate, bis[4-(tert-butyl)phenyl]iodonium tetrakis(nonafluoro-tert-butyloxy)aluminate, and diphenyliodonium hexafluorophosphate.

5. The preparation method according to claim 1, characterized in that: The first free radical initiator and the second free radical initiator are each independently selected from one or more of benzopinacol, dibenzoyl peroxide, and 1,1-di-tert-butylperoxy-3,3,5-trimethylcyclohexane.

6. The preparation method according to claim 1, characterized in that: The front-end polymerization is initiated by light or heat.

7. The preparation method according to claim 6, characterized in that: The wavelength of the light triggering is 365-405 nm.

8. The preparation method according to claim 6, characterized in that: The thermal initiation temperature is 250-350°C.

9. The interpenetrating polymer network prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the interpenetrating polymer network according to claim 9 in the field of electronic component packaging.

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