Aromatic amine curing agent, synthetic method thereof, epoxy resin composition and application

Abstract

The invention discloses an aromatic amine curing agent, a synthesis method thereof, an epoxy resin composition and application. The chemical general formula of the aromatic amine curing agent is shown in the specification, wherein R1 and R2 are one or two of methyl, ethyl, tertiary butyl and sec-butyl; and n is 1-5. A cured product of the aromatic amine curing agent and epoxy resin has the characteristics of low thermal expansion coefficient, flame retardance, high temperature resistance, low dielectric property, good comprehensive mechanical property and the like, and solves the problems that the thermal expansion coefficient of bottom filling glue of a gap between an existing semiconductor element and a circuit substrate is relatively high, the bottom filling glue is not matched with a chip, and the flame retardance is not realized; and the effects of protecting welding spots, dispersing mechanical stress and improving the thermal mechanical reliability between the chip and the substrate are achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and particularly relates to an aromatic amine curing agent and a synthesis method thereof, an epoxy resin composition and applications. Background Art

[0002] Aromatic amine curing agents have good heat resistance, and their cured products have excellent mechanical properties, dielectric properties, corrosion resistance and high heat deformation temperature, and are used in the field of component sealing of electronic components such as transistors and ICs. In particular, in semiconductor devices equipped with bare chips, liquid resin compositions for electronic components (aromatic amine curing agents and epoxy resins) are mainly used as bottom filling materials for filling the gaps between the semiconductor elements and the circuit substrates connected by protrusions. However, traditional aromatic amine curing agents have three defects. First, conventional aromatic amine curing agents have phase defects. Due to the rigid stacking effect of the aromatic rings in its crystal structure, the melting point of the material is significantly higher than the ambient temperature (usually >40°C), and it exhibits solid physical properties under standard operating conditions of 25°C. In actual application, additional heat energy needs to be applied for melting treatment to achieve uniform mixing with the epoxy resin matrix, which seriously restricts its process applicability under room temperature operating conditions; secondly, the problem of thermomechanical property mismatch is prominent. The linear coefficient of thermal expansion (CTE) of existing aromatic amine cured products generally remains at 60-80ppm / K, which is an order of magnitude different from that of semiconductor chip materials (3-5ppm / K). This mismatch in thermomechanical parameters will lead to the accumulation of interfacial shear stress under temperature cycling conditions, ultimately causing reliability failures such as chip / packaging material interface delamination and micro-bump fracture; furthermore, the thermal stability and safety performance are insufficient. The glass transition temperature (Tg) of traditional system cured products is mostly below 150°C, and there is a lack of effective flame retardant mechanism design. Under conditions of continuous chip operating temperature (>125°C) and sudden thermal shock, thermal decomposition is prone to occur, resulting in mechanical strength degradation, and there is also a safety hazard of substandard flammability rating. The bottom filler needs to have a high glass transition temperature (Tg) to achieve high temperature resistance, mainly due to its mechanical performance stability, thermal expansion matching and long-term reliability guarantee in high temperature environments. The glass transition temperature (Tg) is the critical temperature at which a polymer transitions from a rigid glassy state to a soft rubbery state. Above the Tg, the material's modulus plummets, leading to a loss of mechanical strength. The softened underfill is unable to effectively dissipate stress, making the solder joints susceptible to mechanical shock or vibration damage. Creep resistance is reduced, and sustained stress at high temperatures (such as the weight of the chip itself or package pressure) causes the underfill to slowly deform (creep), inducing fatigue cracking in the solder joints. Before the Tg, at low temperatures, the underfill is in a glassy state with a low CTE (typically 50 ppm / °C), and the CTE difference with the chip and substrate is manageable. However, above the Tg, the underfill enters a rubbery state, and its CTE increases dramatically to 100-150 ppm / °C. This exacerbates the thermal mismatch with the surrounding materials, generating significant thermal stresses that can lead to interfacial delamination or solder joint fracture. Furthermore, there's the issue of high-temperature aging. In long-term high-temperature environments, such as those in the automotive electronics industry (industry standard AEC-Q100), underfills are required to withstand 1000 hours of continuous operation at 150°C without failure.Low-Tg materials are prone to molecular chain breakage and decreased crosslinking, leading to performance degradation. Regarding flame retardancy, high-performance computing semiconductor chips can generate power of up to 100W-500W, generating significant heat. The commercially available liquid aromatic amine curing agent 6,6'-methylenebis(2-ethylaniline) cured with epoxy resin 4032D exhibits a peak heat release rate (pHRR) of 402.6W / g, but lacks flame retardancy and poses a safety hazard. Finally, regarding dielectric properties, with the widespread adoption of technologies such as 5G communications, high-speed computing (such as AI chips), and millimeter-wave radar, the operating frequencies of electronic devices have increased to GHz or even THz levels. The dielectric properties of a material directly impact signal transmission quality. The lower the dielectric constant, the faster the signal propagation speed, thereby reducing signal latency. Lower dielectric loss (dissipation factor) minimizes energy loss during signal transmission, preventing signal attenuation and heat generation. Low dielectric properties in underfill are a core requirement for high-frequency, high-density electronic packaging, directly impacting signal transmission speed, power consumption, and system reliability. Driven by 5G, AI, autonomous driving and other fields, material research and development needs to continuously optimize dielectric properties. In the future, through nanocomposites, multi-scale structural design and the development of new resins, low-dielectric fillers will further enhance the performance limits of high-frequency devices. Therefore, in order to meet the stringent requirements of modern high-density, high-frequency electronic devices for signal integrity, transmission efficiency and reliability, the bottom filler also needs to have the characteristic of low dielectricity. In addition, in order to ensure strong bonding and cope with interference from external environmental factors during use, the overall mechanical properties of the bottom filler need to be good.

[0003] In summary, it is particularly important to develop an aromatic amine curing agent so that the cured product thereof with epoxy resin has the characteristics of low thermal expansion coefficient, flame retardancy, high temperature resistance, low dielectric constant, and good comprehensive mechanical properties. Summary of the Invention

[0004] The present invention aims to provide a liquid aromatic amine curing agent. The cured product of the aromatic amine curing agent and epoxy resin has the characteristics of low thermal expansion coefficient, flame retardancy, high temperature resistance, low dielectric constant, and good comprehensive mechanical properties. The curing product solves the problems of the existing bottom filling glue in the gap between semiconductor components and circuit substrates having a high thermal expansion coefficient, mismatch with the chip, and non-flame retardancy. The curing product protects solder joints, disperses mechanical stress, and improves the thermal mechanical reliability between the chip and the substrate.

[0005] To achieve the above-mentioned purpose of the invention, the present invention provides an aromatic amine curing agent, the general chemical formula of which is:

[0006]

[0007] Wherein R1 and R2 are one or two of methyl, ethyl, tert-butyl and sec-butyl; n is 1-5; preferably, n is 2 or 3 or 4.

[0008] The present invention provides a method for synthesizing an aromatic amine curing agent, comprising the following steps:

[0009] (1) A reaction product to be purified is obtained by condensing an alkyl-substituted aniline and a biphenyl-containing monomer in the presence of a weak reducing agent and a strong acid catalyst under certain reaction conditions;

[0010] (2) The reaction product is adjusted to neutral pH by using an alkaline pH regulator, and then subjected to rotary evaporation, and is washed with one or more solvents and dried to obtain an aromatic amine curing agent.

[0011] Optionally, the solvent includes at least one of petroleum ether, isopropyl alcohol, ethanol, water, toluene, and chloroform;

[0012] Optionally, the alkyl-substituted aniline is at least one of o-ethylaniline, o-methylaniline, o-tert-butylaniline, and o-sec-butylaniline;

[0013] Optionally, the biphenyl group-containing monomer is at least one of 4,4'-biphenyl dimethyl dimethyl ether, 4,4'-dichloromethyl biphenyl and 4,4'-dibromomethyl biphenyl;

[0014] Optionally, the strong acid catalyst is one or a combination of concentrated hydrochloric acid, concentrated sulfuric acid, concentrated nitric acid, perchloric acid, hydrobromic acid and hydroiodic acid;

[0015] Optionally, the weak reducing agent is one or a combination of sodium triacetoxyborohydride, sodium borohydride, lithium tri-sec-butylborohydride, sodium cyanoborohydride borane-tetrahydrofuran and catechol borane;

[0016] Optionally, the alkaline pH regulator is an organic base or an inorganic base, and the inorganic base is one or a combination of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate and ammonia water.

[0017] Optionally, the reaction temperature is 150-180° C. and the reaction time is 4-6 hours.

[0018] Optionally, the molar ratio of the alkyl-substituted aniline to the biphenyl-containing monomer is 3:(2-2.5).

[0019] The present invention provides an epoxy resin composition comprising the aromatic amine curing agent and an epoxy resin.

[0020] Optionally, the content of the aromatic amine curing agent in the epoxy resin composition is 35-55 wt %.

[0021] Optionally, the epoxy resin is any one or a combination of 4032D epoxy resin, AG-80 epoxy resin, NC3000L epoxy resin, AG-80 epoxy resin, bisphenol A epoxy resin, bisphenol F epoxy resin, and YX4000 epoxy resin.

[0022] The present invention provides an application of the epoxy resin composition, which is applied to the fields of electronic packaging materials, aerospace composite materials or automotive component composite materials.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] Compared with the aromatic amine curing agent of the prior art, the preparation method of the aromatic amine curing agent of the present invention: with o-ethylaniline and monomer containing biphenyl group as raw materials, under the action of strong acid catalyst, in the reaction process, by adjusting the spatial configuration or molecular dipole of curing agent molecule in o-ethylaniline by amino group, the active group in the monomer containing biphenyl group is attacked thereby replacing the hydrogen in the para or ortho position of amino group in o-ethylaniline (it is worth noting that, because amino group has the influence on whole molecular spatial configuration and molecular dipole, can preferably attack para position, secondly ortho position); Because the nitrogen atom on amino group (-NH2) in o-ethylaniline has a pair of lone electron pairs, can be delocalized to the large π system of benzene ring by p-π effect. Make benzene ring ortho and para position obtain partial negative charge, electron cloud density significantly improves. Attract electrophilic reagent to preferentially attack these positions. Can effectively reduce the influence of meta-substitution side reaction on product yield, suppress the active group in the monomer containing biphenyl group to attack carbon-hydrogen bond on o-ethylaniline meta position, avoid containing biphenyl group and o-ethylaniline meta position being connected, thus improve productive rate. The addition of biphenyl structures to amine curing agents can, firstly, lead to localized aggregation due to the π-π interaction, thereby increasing the modulus and lowering the CTE. Secondly, it can significantly increase the glass transition temperature. As rigid planar structures, the large bulk of the biphenyl group hinders free rotation of the molecular chain, restricting segmental motion. The conjugated structure between the benzene rings enhances the rigidity of the molecular chain, requiring higher energy to initiate segmental motion. Therefore, its inclusion reduces the flexibility of the curing agent's molecular chain, raising the energy barrier for segmental motion in the glassy state and significantly increasing the glass transition temperature. The π electron clouds between the benzene rings interact to form an ordered arrangement, enhancing intermolecular attractions. The rigid biphenyl structure promotes close packing of the molecular chains, reducing free volume, thereby strengthening intermolecular forces. Breaking these interactions requires higher temperatures, further increasing the Tg. The rigidity of the biphenyl group may slightly reduce the crosslink density, but the dominant effect of chain rigidity makes its contribution to Tg outweigh the influence of crosslink density. The rigid groups reduce network defects, creating a more uniform stress distribution and inhibiting segmental motion. Thereby optimizing the hierarchical cross-linked network structure, in summary, the introduction of biphenyl groups significantly improves the glass transition temperature of the cured product of amine curing agents by enhancing the rigidity of the molecular chain, strengthening the intermolecular force, optimizing the cross-linked network and other mechanisms. Thirdly, strengthening the intermolecular interaction can achieve a flame retardant effect. The biphenyl group significantly enhances the flame retardant properties of the amine curing agent system by promoting carbonization, capturing free radicals, improving thermal stability and synergistic flame retardant effect. This strategy has important application value in high-performance flame retardant epoxy resins (such as electronic packaging materials, aerospace composite materials). Fourthly, the biphenyl group significantly reduces the dielectric constant of the amine curing agent system by reducing polarity, suppressing polarization behavior, enhancing hydrophobicity and optimizing the cross-linked network. In summary, the introduction of biphenyl groups in aromatic amine curing agents has key application value in the field of semiconductor packaging.

[0025] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are specifically listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of the preparation process of the aromatic amine curing agent according to Example 1 of the present invention;

[0027] Figure 2 is a gel permeation chromatogram (GPC) of the aromatic amine curing agent of Example 1 of the present invention;

[0028] Figure 3 This is the H NMR spectrum of the aromatic amine curing agent of Example 1 of the present invention;

[0029] Figure 4 This is an infrared spectrum of the aromatic amine curing agent of Example 1 of the present invention;

[0030] 5( a ) and 5 ( b ) are graphs showing the relationship between the storage modulus and the loss modulus and the temperature of the epoxy resin compositions of Example 4 of the present invention and Comparative Example 2;

[0031] Figure 6 2 is a graph showing the thermal expansion coefficients of the epoxy resin compositions of Example 4 of the present invention and Comparative Example 2;

[0032] Figure 7 Graph showing HRR (heat release rate) versus temperature for the epoxy resin compositions of Example 4 of the present invention and Comparative Example 2;

[0033] Figure 8 1 is a graph showing the relationship between the dielectric constant, dielectric loss and frequency of the epoxy resin compositions of Example 4 of the present invention and Comparative Example 2;

[0034] Figure 9 4 is a graph showing the mechanical properties of the epoxy resin compositions of Example 4 of the present invention and Comparative Example 2;

[0035] Figure 10 Graph showing the adhesion of the epoxy resin compositions of Example 4 and Comparative Example 2 on the surface of an aluminum sheet; DETAILED DESCRIPTION

[0036] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0037] In this disclosure, the term "and / or" describes the relationship between associated objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A exists alone, A and B exist simultaneously, and B exists alone. A and B can be singular or plural. The character " / " generally indicates that the associated objects are in an "or" relationship.

[0038] In the present invention, "at least one" means one or more, and "plurality" means two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, "at least one of a, b, or c" or "at least one of a, b, and c" can all mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can each be single or plural.

[0039] It should be understood that in various embodiments of the present invention, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. Some or all of the steps can be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0040] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The singular forms "a", "an", "the" and "the" used in the embodiments of the present invention and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise.

[0041] The term "Tg," short for "glass transition temperature," refers to the temperature at which a polymer transitions from a glassy state to a highly elastic state. Tg is the lowest temperature at which molecular chains can move, representing the relaxation of the amorphous portion of a polymer from a frozen state to a thawed state.

[0042] The following description will be made in conjunction with specific examples. The examples described below are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention. Where specific techniques or conditions are not specified in the examples, the techniques or conditions described in the literature in this area or the product specifications are used. Where the manufacturer of the reagents or instruments is not specified, all are commercially available conventional products.

[0043] Example 1

[0044] This embodiment provides a biphenyl group-containing liquid aromatic amine curing agent, the preparation method of which comprises the following steps:

[0045] 1. Using 4,4'-biphenyl dimethyl dimethyl ether and o-ethylaniline as raw materials, a reaction was performed to obtain an aromatic amine curing agent. The specific steps were as follows: 18.15g o-ethylaniline and 30.25g 4,4'-biphenyl dimethyl dimethyl ether were placed in a 250ml three-necked flask at room temperature, mixed evenly in the flask, and 3 drops of sodium cyanoborohydride were added. The mixture was heated in an oil bath set at 150°C. Once the raw materials were completely mixed and the temperature rose to above 135°C, 5% concentrated hydrochloric acid was added. The mixture was then stirred under a nitrogen atmosphere for 5 hours.

[0046] 2. After the three-necked flask has cooled to room temperature, add 80°C NaOH aqueous solution in small amounts and several times until the pH of the product is neutral. Separate the organic layer, wash it with deionized water, and remove the solvent by rotary evaporation.

[0047] 3. The reaction product obtained in step 2 is further purified. At this time, the reaction product contains impurities such as water, unreacted ethylaniline and 4,4'-biphenyldimethyl dimethyl ether. The product is rotary evaporated, and then solvent washed with petroleum ether, isopropyl alcohol and ethanol in sequence, and finally dried to obtain the final product.

[0048] Example 2

[0049] An embodiment of the present invention provides a biphenyl group-containing liquid aromatic amine curing agent, and a preparation method thereof comprises the following steps:

[0050] 1. Use 4,4'-biphenyl dimethyl dimethyl ether and o-ethylaniline as raw materials, and react to obtain an amine curing agent. The specific steps are to use o-ethylaniline and 4,4'-biphenyl dimethyl dimethyl ether as raw materials, 18.15g of o-ethylaniline and 30.25g of 4,4'-biphenyl dimethyl dimethyl ether, in a ratio of 3:2.5, mix them evenly in a flask, add 3 drops of sodium cyanoborohydride, and heat in an oil bath set at 150°C. When the raw materials are completely mixed and the temperature rises to above 135°C, add 1% by mass concentrated sulfuric acid. Thereafter, add 1% by mass concentrated sulfuric acid every 1.5 hours of reaction under a nitrogen atmosphere. Repeat 3 times for a total of 3% by mass concentrated sulfuric acid and react for 5 hours. Obtain the product to be purified;

[0051] 2. The pH of the product to be purified obtained in step 1 is adjusted to neutral, and the specific steps are the same as those in Example 1;

[0052] 3. The reaction product obtained in step 2 is further purified. The reaction product contains impurities such as water, unreacted raw material o-ethylaniline, and 4,4'-biphenyl dimethyl dimethyl ether. The product is rotary evaporated, and then solvent washed with petroleum ether, isopropyl alcohol, and ethanol in sequence, and finally dried to obtain the final product.

[0053] Example 3

[0054] An embodiment of the present invention provides a biphenyl group-containing liquid aromatic amine curing agent, the preparation of which comprises the following steps:

[0055] 1. Use 4,4'-biphenyl dimethyl dimethyl ether and o-ethylaniline as raw materials, and obtain an amine curing agent through reaction. The specific steps are to add 18.15g o-ethylaniline and 30.25g 4,4'-biphenyl dimethyl dimethyl ether in a 250ml three-necked flask in a ratio of 3:2.5, mix them evenly in the flask, add 3 drops of sodium cyanoborohydride, and heat in an oil bath pot set at a temperature of 150℃. When the raw materials are completely mixed and the temperature rises to above 135℃, add 0.67% concentrated sulfuric acid by mass. After that, add 0.67% concentrated sulfuric acid by mass every 1.5h of reaction under nitrogen atmosphere. Repeat 3 times for a total of 2% concentrated sulfuric acid by mass and react for 5 hours. Obtain the product to be purified;

[0056] 2. The pH of the product to be purified obtained in step 1 is adjusted to neutral. The specific steps are the same as those in Example 1;

[0057] 3. The reaction product obtained in step 2 was further purified by the same specific steps as in Example 1 to obtain the target product.

[0058] Example 4

[0059] An epoxy resin composition comprises the aromatic amine curing agent prepared in Example 1 and 4032D epoxy resin, wherein the mass ratio of the aromatic amine curing agent prepared in Example 1 to the 4032D epoxy resin is 0.87g:1g.

[0060] Example 5

[0061] An epoxy resin composition includes the aromatic amine curing agent prepared in Example 2 and 4032D epoxy resin, wherein the mass ratio of the aromatic amine curing agent prepared in Example 1 to the 4032D epoxy resin is 0.87g:1g.

[0062] Example 6

[0063] An epoxy resin composition includes the aromatic amine curing agent prepared in Example 3 and 4032D epoxy resin, wherein the mass ratio of the aromatic amine curing agent prepared in Example 1 to the 4032D epoxy resin is 0.87g:1g.

[0064] Comparative Example 1

[0065] 6,6'-methylenebis(2-ethylaniline) having the following structural formula is used as an aromatic amine curing agent.

[0066]

[0067] Comparative Example 2

[0068] An epoxy resin composition comprises the 6,6'-methylenebis(2-ethylaniline) aromatic amine curing agent of comparative example 1 and a 4032D epoxy resin, wherein the mass ratio of the 6,6'-methylenebis(2-ethylaniline) aromatic amine curing agent of comparative example 1 to the 4032D epoxy resin is 0.46g:1g; and testing shows that the molar ratio of amino groups in the curing agent relative to the epoxy resin is the same as that in the embodiment.

[0069] Performance Testing

[0070] In order to verify the advancement of the aromatic amine curing agent and the composition thereof with epoxy resin in the embodiments of the present invention, the following performance tests were conducted on the above embodiments:

[0071] 1. Gel Permeation Chromatography (GPC): A room temperature water / oil phase GPC (515) was used to determine the molecular weight of the synthesized aromatic amine curing agent.

[0072] 2. Liquid nuclear magnetic resonance spectrometer (NMR): 1H NMR spectra were measured using a Bruker DPX-400 spectrometer (400 MHz) to further explore the chemical structure of the epoxy monomer.

[0073] 3. Fourier transform infrared spectrometer (FTIR): Nicolet Nexus 670 spectrometer was used, KBr pellet method was adopted, and the wave number range of infrared spectrum was 500-3500 cm -1 , with a resolution of 4cm -1 .

[0074] 4. Viscosity test: Anton Paar (MCR102) rheometer was used to study the rheological behavior of epoxy monomer at a rotation speed of 1 rad / s and a temperature of 25°C.

[0075] 5. Dynamic Mechanical Analyzer (DMA): The thermomechanical properties of epoxy resin cured products were tested using a dynamic mechanical analyzer (DMA, TA Instruments Q800) at a heating rate of 3 K / min and an oscillation frequency of 1 Hz.

[0076] 6. Microcalorimeter: At a heating rate of 1 k / s, use the instrument MCC_2 from Comark to test the heat release rate, peak heat release rate, total heat released, and temperature corresponding to the maximum heat release rate of the cured product.

[0077] 7. Dielectric performance test: at 25℃, 10 4 -10 7 The dielectric properties of fluorinated acrylate were measured using a precision impedance analyzer (Agilent 4294A) in the Hz frequency range.

[0078] 8. Tensile Test: The mechanical properties of the epoxy resin composition were tested using a universal mechanical testing machine at a tensile rate of 10 mm / min. The mechanical property data were the average of five samples.

[0079] The specific test data is shown in Figure 1. Figure 2 As shown in FIG. 1 , the gel permeation chromatography (GPC) diagram of the aromatic amine curing agent prepared in Example 1 is shown.

[0080] Table 1

[0081] sample Mn (mg) Mw(mg) Mp Mz Mv Polydispersity Example 1 666 749 675 883 734 1.125

[0082] The GPC test results in Table 1 above show that the reaction product, an aromatic amine curing agent, has a number average molecular weight (Mn) of 666 g / mol, a weight average molecular weight (Mw) of 749 g / mol, a peak molecular weight (Mp) of 675 g / mol, and a polydispersity index (PDI) of 1.125. This is consistent with the molecular weight of the synthesized amine curing agent, which is 719 g / mol.

[0083] like Figure 4 As shown, 1260cm -1 The infrared peak represents the -COC- in the aromatic amine curing agent synthesized in Example 1, combined with Figure 2 Gel permeation chromatography GPC diagram, Figure 3 The H NMR spectrum and IR spectrum showed that the target product had been synthesized.

[0084] The viscosity performance test of the aromatic amine curing agent prepared in Example 1 and the aromatic amine curing agent prepared in Comparative Example 1 was carried out. The test results are shown in Table 2.

[0085] Table 2

[0086] sample Viscosity (mPa.s) / 25℃ Viscosity (mPa.s) / 170℃ Comparative Example 1 4125.3 1.84 Example 1 5288.4 2.28

[0087] The test results of the coefficient of thermal expansion parameters are shown in Figure 5. Compared with the epoxy resin composition of Comparative Example 2, the CTE of the epoxy resin composition of Example 4 is lower than that of Comparative Example 2 at all temperatures. Because its glass transition temperature (180°C) is higher than that of Comparative Example 2 (136°C), its CTE sudden rise process also lags behind that of Comparative Example 2.

[0088] The glass transition temperature of the cured product of aromatic amine curing agent and epoxy resin was tested using a dynamic mechanical analyzer (DMA). The test results are shown in Table 3 below:

[0089] Table 3

[0090] performance Example 4 Example 5 Example 6 Comparative Example 2 Tg(℃) 180 140 164 136

[0091] As shown in the test results in Table 3, the glass transition temperatures of the epoxy resin compositions of Examples 4, 5, and 6 of the present invention are all higher than the glass transition temperature (136°C) of the epoxy resin composition of Comparative Example 2, demonstrating improved heat resistance. Furthermore, Example 4 exhibits the highest glass transition temperature (180°C), demonstrating the optimal curing agent synthesis scheme.

[0092] Depend on Figure 7 As can be seen, the HRR (heat release rate) of the epoxy resin composition of Example 4 and the epoxy resin composition of Comparative Example 2 changes with temperature, showing roughly the same trend: initially increasing and then decreasing with increasing temperature. The peak pHRR heat release rate (maximum heat release per unit time) of Comparative Example 2 is 402.6 (W / g), while that of Example 4 is 280.8 (W / g). This indicates that the peak heat release rate of the epoxy resin composition of Example 4 is 30.3% lower, resulting in better flame retardancy.

[0093] In addition, a microcalorimeter was used to test the mass change before and after combustion, heat release rate, total release rate, etc. The test results are shown in Table 4 below:

[0094] Table 4

[0095]

[0096] From the test results in Table 4 above, it can be seen that the HRC heat release capacity of the epoxy resin composition of Comparative Example 2 (reflecting the "efficiency" of heat release during the thermal decomposition process of the material) is 456 J / gk, while the epoxy resin composition of Example 4 is even lower at 316 J / gk, indicating that the heat released by the embodiment system material when heated is more gradual and the combustion is more controllable, which is suitable for heat-sensitive application scenarios such as electronic packaging. For the total heat release rate THR (the total heat released by combustion of a unit mass sample, reflecting the potential hazards of material combustion), the comparative example 2 is 27.2 kJ / g and the embodiment 4 is 25.8 kJ / g, a decrease of 5.1%, which also verifies that the embodiment 4 has better flame retardancy. In addition, the ignition temperature of the comparative example 2 is 417.3 ° C, and the ignition temperature of the embodiment 4 is higher at 423.5 ° C, which also verifies that the embodiment 4 system has better flame retardancy.

[0097] Depend on Figure 8 The dielectric constant and dielectric loss test results show that at a frequency of 10 7 At HZ, the dielectric constant of the epoxy resin composition of Example 4 of the present invention is 3.02, while the dielectric constant of the epoxy resin composition of Comparative Example 2 is 3.21. The dielectric constant of Example 4 is reduced by 5.92% relative to that of Comparative Example 2.

[0098] Depend on Figure 9It can be seen from the mechanical property curve that the maximum stress of the epoxy resin composition of Example 4 of the present invention is 40.19 MPa, the maximum strain is 10.82%, and the Young's modulus is 0.37 Gpa; the maximum stress of the epoxy resin composition of Comparative Example 2 is 84.07 MPa, the maximum strain is 16.22%, and the Young's modulus is 0.52 Gpa; therefore, compared with Comparative Example 2, Example 4 has larger stress, strain and Young's modulus, and has stronger ability to resist deformation.

[0099] Depend on Figure 10 The tensile-shear test of the aluminum sheet surface adhesion shows that the epoxy resin composition of Example 4 of the present invention has a maximum surface adhesion of 15.03 MPa, while the epoxy resin composition of Comparative Example 2 has a maximum surface adhesion of 12.84 MPa. The epoxy resin composition of Example 4 has a greater adhesion.

[0100] In summary, the aromatic amine curing agent containing a biphenyl group of the present invention can significantly improve the comprehensive performance of epoxy resin cured products used for bottom filling glue in the gap between semiconductor components and circuit substrates. The epoxy resin cured products have the advantages of low thermal expansion coefficient, flame retardancy, high temperature resistance, low dielectric constant, high deformation resistance and high adhesion.

Claims

1. An aromatic amine curing agent, characterized in that The general chemical formula is: Wherein R1 and R2 are one or two of methyl, ethyl, tert-butyl and sec-butyl; and n is 1-5.

2. The aromatic amine curing agent according to claim 1, characterized in that The n is 2, 3 or 4.

3. A method for synthesizing the aromatic amine curing agent according to claim 1 or 2, characterized in that: The following steps are involved: (1) A reaction product to be purified is obtained by condensing an alkyl-substituted aniline and a biphenyl-containing monomer in the presence of a weak reducing agent and a strong acid catalyst under certain reaction conditions; (2) The reaction product is adjusted to neutral pH by using an alkaline pH regulator, and then subjected to rotary evaporation, and is washed with one or more solvents and dried to obtain an aromatic amine curing agent.

4. The method for synthesizing the aromatic amine curing agent according to claim 3, characterized in that: The solvent includes at least one of petroleum ether, isopropyl alcohol, ethanol, water, toluene, and chloroform; and / or, the alkyl-substituted aniline is at least one of o-ethylaniline, o-methylaniline, o-tert-butylaniline, and o-sec-butylaniline; and / or, the biphenyl group-containing monomer is at least one of 4,4'-biphenyl dimethyl dimethyl ether, 4,4'-dichloromethyl biphenyl and 4,4'-dibromomethyl biphenyl; and / or, the strong acid catalyst is one or a combination of concentrated hydrochloric acid, concentrated sulfuric acid, concentrated nitric acid, perchloric acid, hydrobromic acid and hydroiodic acid; and / or, the weak reducing agent is one or a combination of sodium triacetoxyborohydride, sodium borohydride, lithium tri-sec-butylborohydride, sodium cyanoborohydride borane-tetrahydrofuran and catechol borane; And / or, the alkaline pH regulator is an organic base or an inorganic base, and the inorganic base is one or a combination of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate and ammonia water.

5. The method for synthesizing the aromatic amine curing agent according to claim 3 or 4, characterized in that: The reaction conditions are a temperature of 150-180° C. and a time of 4-6 hours.

6. The method for synthesizing the aromatic amine curing agent according to claim 3 or 4, characterized in that: The molar ratio of the alkyl-substituted aniline to the biphenyl-containing monomer is 3:(2-2.5).

7. An epoxy resin composition, characterized in that The invention comprises an aromatic amine curing agent prepared by the synthesis method according to claim 1 or 2 or any one of claims 3 to 6, and an epoxy resin.

8. The epoxy resin composition according to claim 7, wherein The content of the aromatic amine curing agent in the epoxy resin composition is 35-55 wt %.

9. The epoxy resin composition according to claim 7 or 8, wherein The epoxy resin is any one or a combination of 4032D epoxy resin, AG-80 epoxy resin, NC3000L epoxy resin, AG-80 epoxy resin, bisphenol A epoxy resin, bisphenol F epoxy resin, and YX4000 epoxy resin.

10. Use of the epoxy resin composition according to any one of claims 7 to 9, characterized in that: It is used in the fields of electronic packaging materials, aerospace composite materials or automotive component composite materials.

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