Preparation method of epoxy modified silicone oil and application of epoxy modified silicone oil in temperature-resistant structural adhesive

Abstract

The invention belongs to the technical field of structural bonding, and particularly relates to a preparation method of epoxy modified silicone oil and application of the epoxy modified silicone oil in a temperature-resistant structural adhesive. According to the invention, gamma-glycidyl ether oxypropyl methyl dimethoxy silane, dimethoxy (methyl) phenyl silane and hexamethyl dimethoxy silane are used as raw materials to prepare methyl phenyl epoxy modified silicone oil (Ph-EpSO), and the methyl phenyl epoxy modified silicone oil (Ph-EpSO), 170 type epoxy resin, a dicyandiamide curing agent and an auxiliary agent are used to prepare the temperature-resistant structural adhesive (TRSA). By optimizing the ratio of the epoxy group to the phenyl group in the synthesized methyl phenyl epoxy modified silicone oil, the temperature-resistant structural adhesive does not crack after being subjected to cold and hot impact at the temperature of 40-140 DEG C for 24 rounds, and meanwhile, the bending part does not have cracking and whitening phenomena; the direct current breakdown voltage and the alternating current breakdown voltage at the bending part after 24 rounds of hot and cold shock are 4.21 kV and 3.05 kV respectively; the shearing force is 6.091 Mpa, and the adhesive has relatively good temperature resistance, pressure resistance and adhesive property.

Description

Technical Field

[0001] The present invention belongs to the technical field of structural bonding, and in particular relates to a preparation method of epoxy-modified silicone oil and application of the same in heat-resistant structural adhesives. Background Art

[0002] Structural adhesives, as high-performance bonding materials, offer significantly superior mechanical properties compared to conventional adhesives. They are specifically designed for reinforcing and connecting load-bearing components, demonstrating exceptional performance in bonding steel substrates. They offer excellent aging, fatigue, and corrosion resistance, ensuring high stability throughout their service life. Structural adhesives are primarily used for bonding metals, ceramics, plastics, rubber, and other materials, and can replace some traditional welding, riveting, and bolting methods. Epoxy resin structural adhesives, as an important general-purpose adhesive, are widely used in the automotive, electronics, and machinery manufacturing industries due to their excellent mechanical properties, chemical resistance, and thermal stability. These adhesives support a variety of curing methods, including high-temperature, medium-high-temperature, room-temperature, and low-temperature curing. High-temperature epoxy structural adhesives are specifically designed to provide strong, durable bonds in high-temperature environments. These adhesives are characterized by their ability to maintain bond strength, structural integrity, and other mechanical properties even at elevated temperatures.

[0003] Traditional high-temperature epoxy structural adhesives usually have the defect of poor impact resistance. Their performance may decrease in high or low temperature environments and cannot meet the requirements of use under extreme temperature conditions. In addition, in the pursuit of high strength, traditional structural adhesives often sacrifice toughness, which makes the substrate prone to cracking or breaking when it is impacted, deformed or vibrated. Epoxy resin has good comprehensive mechanical properties, strong adhesion, low shrinkage and good stability. However, it has the process defects of high viscosity and low leveling. The three-dimensional network structure formed during its curing process is too dense, resulting in the concentration of curing shrinkage stress, causing the material to exhibit mechanical characteristics of insufficient toughness and significant brittleness. This greatly limits the application of epoxy resin in some high-tech fields, especially for structural materials.

[0004] Therefore, how to improve the temperature resistance, toughness and pressure resistance of epoxy structural adhesives is particularly important. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, the present invention provides a method for preparing an epoxy-modified silicone oil and its application in heat-resistant structural adhesives. By implanting epoxy molecules into polysiloxane segments and optimizing the raw material ratio, an epoxy-modified silicone oil with unique properties can be synthesized. This novel material exhibits significant advantages in the formulation design of structural adhesives. It not only effectively overcomes the poor high-temperature resistance and brittleness of epoxy resin structural adhesives currently on the market, but also improves the overall performance of the adhesive, making it more suitable for a variety of harsh working environments.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] The first aspect of the present invention provides a method for preparing epoxy-modified silicone oil, comprising the following steps:

[0008] (1) mixing γ-glycidyloxypropylmethyldimethoxysilane, dimethoxy(methyl)phenylsilane, hexamethyldimethoxysilane, tetramethylammonium hydroxide pentahydrate, and deionized water, stirring and heating the mixture under an inert gas environment;

[0009] (2) After removing the inert gas, continue to heat the reaction;

[0010] (3) distillation under reduced pressure, cooling, and then adding acetic acid dropwise to remove the base until the pH value is 6-7 to obtain epoxy-modified silicone oil.

[0011] The preparation route of the epoxy modified silicone oil is as follows:

[0012]

[0013] Preferably, the molar ratio of the γ-glycidyloxypropylmethyldimethoxysilane to dimethoxy(methyl)phenylsilane is 1:1 to 5:1.

[0014] More preferably, the molar ratio of the γ-glycidyloxypropylmethyldimethoxysilane to dimethoxy(methyl)phenylsilane is 2:1.

[0015] Preferably, the mass of the tetramethylammonium hydroxide pentahydrate is 0.004 times the total mass of γ-glycidyloxypropylmethyldimethoxysilane, dimethoxy(methyl)phenylsilane and hexamethyldimethoxysilane.

[0016] Preferably, the molar amount of the deionized water is 1.6 times the total molar amount of γ-glycidyloxypropylmethyldimethoxysilane and dimethoxy(methyl)phenylsilane.

[0017] The second aspect of the present invention provides an epoxy-modified silicone oil prepared by the above preparation method.

[0018] The third aspect of the present invention provides an application of the above-mentioned epoxy-modified silicone oil in heat-resistant structural adhesive. The preparation method of the heat-resistant structural adhesive is: epoxy-modified silicone oil, epoxy resin, curing agent, defoaming agent, and leveling agent are evenly mixed, heated and cured to obtain the cured heat-resistant structural adhesive.

[0019] Preferably, the epoxy resin is 170 type epoxy resin, the curing agent is dicyandiamide, the defoaming agent is RT-501 defoaming agent, and the leveling agent is BYK-333 leveling agent.

[0020] Preferably, the molar ratio of the epoxy-modified silicone oil, epoxy resin and curing agent is 1:1:1.

[0021] Preferably, the mass of the defoaming agent is 1% of the total mass of the epoxy-modified silicone oil, the epoxy resin and the curing agent.

[0022] Preferably, the mass of the leveling agent is 2% of the total mass of the epoxy-modified silicone oil, the epoxy resin and the curing agent.

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

[0024] The present invention first adopts a hydrolysis-polycondensation method to prepare methylphenyl epoxy modified silicone oil (Ph-EpSO), then uses Ph-EpSO and 170 epoxy resin as main materials, and supplements with dicyandiamide curing agent, leveling agent, defoaming agent and other auxiliary agents to prepare heat-resistant structural adhesive (TRSA). By optimizing the ratio of epoxy group to phenyl group in the synthesized methylphenyl epoxy modified silicone oil (-Ep / -Ph=2 / 1), the transmittance of the methylphenyl epoxy modified silicone oil at 450nm is 92.13%. The TRSA prepared by combining the Ph-EpSO with 170 epoxy resin, dicyandiamide curing agent and auxiliary agents has excellent heat resistance, insulation performance and bonding performance. Its cured product can withstand 24 rounds of -40 to 140°C hot and cold shocks without cracking, and there is no cracking or whitening at the bends; in the TG test, its T5%, T50% and TMax are 316.12°C, 437.38°C and 423.70°C respectively, all higher than other TRSAs; the glass transition temperature is relatively high, at 113.320°C; the TRSA bends that have undergone 24 rounds of hot and cold shocks are subjected to a withstand voltage test, and at a breakdown current of 0.5mA, the DC and AC breakdown voltages are 4.21kV and 3.05kV respectively; a shear force test is performed on it using a tensile testing machine, and the measured shear force is 6.091Mpa. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 FT-IR test curves of epoxy-modified silicone oil and raw materials with different -Ep / -Ph values ​​in Examples 1-5.

[0026] Figure 2 The epoxy modified silicone oil Ph-EpSO with different -Ep / -Ph values ​​in Examples 1-5 is 1 H NMR spectrum.

[0027] Figure 3 The epoxy modified silicone oil Ph-EpSO with different -Ep / -Ph values ​​in Examples 1-5 is 13 C NMR spectrum.

[0028] Figure 4 The appearance of five groups of samples of epoxy-modified silicone oil Ph-EpSO with different -Ep / -Ph values ​​in Examples 1-5.

[0029] Figure 5 The UV-visible light transmittance of five Ph-EpSOs with different -Ep / -Ph ratios prepared in Examples 1-5.

[0030] Figure 6 This is a diagram showing the effect of the heat-resistant structural adhesive TRSA-2 in Example 2 being coated on a 0.4 mm thick copper sheet.

[0031] Figure 7 These are pictures of the various stages of the TRSA thermal shock resistance test of the heat-resistant structural adhesive cured sheets in Examples 1-5.

[0032] Figure 8 These are pictures of the bending morphology of the heat-resistant structural adhesive cured sheets in Examples 1-5 at various stages of the TRSA cold and hot shock resistance test.

[0033] Figure 9 TG curves of the five heat-resistant structural adhesive cured products in Examples 1-5.

[0034] Figure 10 These are the DSC curves of the five heat-resistant structural adhesive cured products in Examples 1-5. DETAILED DESCRIPTION

[0035] The following is a further description of specific embodiments of the present invention. It should be noted that the description of these embodiments is intended to facilitate understanding of the present invention and does not constitute a limitation of the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0036] The experimental methods in the following examples are conventional methods unless otherwise specified, and the experimental materials used in the following examples are commercially available unless otherwise specified.

[0037] Example 1: Preparation of methylphenyl epoxy modified silicone oil Ph-EpSO-1 and heat resistant structural adhesive TRSA-1

[0038] Take 141.64g of γ-glycidyloxypropylmethyldimethoxysilane, 117.18g of dimethoxy(methyl)phenylsilane, 0.33g of hexamethyldimethoxysilane, 1.04g of tetramethylammonium hydroxide pentahydrate and 37.03g of deionized water and add them into a 500mL four-necked flask connected to a thermometer and a condenser, control the stirring paddle speed to 250r / min, and heat to 70°C; then connect nitrogen and react in a nitrogen environment for 1h; remove nitrogen, heat to 95°C, and react for 3h; distill under reduced pressure at -0.1MPa and 95°C for about 20min; wait until the system temperature drops to 40°C or room temperature, add 1g of acetic acid to remove the alkali, wait for 30min, and measure the pH value to 6-7. The obtained light yellow transparent viscous substance is methylphenyl epoxy modified silicone oil Ph-EpSO-1.

[0039] Take 10g of methylphenyl epoxy modified silicone oil Ph-EpSO-1, 4.25g of 170 type epoxy resin, 1.05g of curing agent dicyandiamide, 0.15g of RT-501 defoaming agent, and 0.3g of BYK leveling agent and mix them evenly. Use a wire rod to coat a 120μm thick heat-resistant structural adhesive on a copper sheet, then place it in a blast drying oven, set the temperature to 180℃, and cure it at this temperature for 20 minutes to obtain the cured heat-resistant structural adhesive cured sheet TRSA-1.

[0040] Example 2: Preparation of methylphenyl epoxy modified silicone oil Ph-EpSO-2 and heat resistant structural adhesive TRSA-2

[0041] Take 181.44g of γ-glycidyloxypropylmethyldimethoxysilane, 75.05g of dimethoxy(methyl)phenylsilane, 0.33g of hexamethyldimethoxysilane, 1.03g of tetramethylammonium hydroxide pentahydrate and 35.57g of deionized water and add them into a 500mL four-necked flask connected to a thermometer and a condenser, control the stirring paddle speed to 250r / min, and heat to 70°C; then connect nitrogen and react in a nitrogen environment for 1h; remove nitrogen, heat to 95°C, and react for 3h; distill under reduced pressure at -0.1MPa and 95°C for about 20min; wait until the system temperature drops to 40°C or room temperature, add 1g of acetic acid to remove the alkali, wait for 30min, and measure the pH value to 6-7. The obtained light yellow transparent viscous substance is methylphenyl epoxy modified silicone oil Ph-EpSO-2.

[0042] Take 7.14g of methylphenyl epoxy modified silicone oil Ph-EpSO-2, 4.25g of 170 type epoxy resin, 1.05g of curing agent dicyandiamide, 0.12g of RT-501 defoaming agent, and 0.25g of BYK leveling agent and mix them evenly. Use a wire rod to coat a 120μm thick heat-resistant structural adhesive on a copper sheet, then place it in a blast drying oven, set the temperature to 180℃, and cure it at this temperature for 20min to obtain the cured heat-resistant structural adhesive cured sheet TRSA-2.

[0043] Example 3: Preparation of methylphenyl epoxy modified silicone oil Ph-EpSO-3 and heat resistant structural adhesive TRSA-3

[0044] Take 200.19g of γ-glycidyloxypropylmethyldimethoxysilane, 55.21g of dimethoxy(methyl)phenylsilane, 0.33g of hexamethyldimethoxysilane, 1.02g of tetramethylammonium hydroxide pentahydrate and 34.89g of deionized water and add them into a 500mL four-necked flask connected to a thermometer and a condenser, control the stirring paddle speed to 250r / min, and heat to 70°C; then connect nitrogen and react in a nitrogen environment for 1h; remove nitrogen, heat to 95°C, and react for 3h; distill under reduced pressure at -0.1MPa and 95°C for about 20min; wait until the system temperature drops to 40°C or room temperature, add 1g of acetic acid to remove the alkali, wait for 30min, and measure the pH value to 6-7. The obtained light yellow transparent viscous substance is methylphenyl epoxy modified silicone oil Ph-EpSO-3.

[0045] Take 6.41g of methylphenyl epoxy modified silicone oil Ph-EpSO-3, 4.25g of 170 type epoxy resin, 1.05g of curing agent dicyandiamide, 0.12g of RT-501 defoaming agent, and 0.23g of BYK leveling agent and mix them evenly. Use a wire rod to coat a 120μm thick heat-resistant structural adhesive on a copper sheet, then place it in a blast drying oven, set the temperature to 180℃, and cure it at this temperature for 20min to obtain the cured heat-resistant structural adhesive cured sheet TRSA-3.

[0046] Example 4: Preparation of methylphenyl epoxy modified silicone oil Ph-EpSO-4 and heat resistant structural adhesive TRSA-4

[0047] Take 211.10g of γ-glycidyloxypropylmethyldimethoxysilane, 43.66g of dimethoxy(methyl)phenylsilane, 0.33g of hexamethyldimethoxysilane, 1.02g of tetramethylammonium hydroxide pentahydrate and 34.49g of deionized water and add them into a 500mL four-necked flask connected to a thermometer and a condenser, control the stirring paddle speed to 250r / min, and heat to 70°C; then connect nitrogen and react in a nitrogen environment for 1h; remove nitrogen, heat to 95°C, and react for 3h; distill under reduced pressure at -0.1MPa and 95°C for about 20min; wait until the system temperature drops to 40°C or room temperature, add 1g of acetic acid to remove the alkali, wait for 30min, and measure the pH value to 6-7. The obtained light yellow transparent viscous substance is methylphenyl epoxy modified silicone oil Ph-EpSO-4.

[0048] Take 5.68g of methylphenyl epoxy modified silicone oil Ph-EpSO-4, 4.25g of 170 type epoxy resin, 1.05g of curing agent dicyandiamide, 0.11g of RT-501 defoaming agent, and 0.22g of BYK leveling agent and mix them evenly. Use a wire rod to coat a 120μm thick heat-resistant structural adhesive on a copper sheet, then place it in a blast drying oven, set the temperature to 180℃, and cure it at this temperature for 20min to obtain the cured heat-resistant structural adhesive cured sheet TRSA-4.

[0049] Example 5: Preparation of methylphenyl epoxy modified silicone oil Ph-EpSO-5 and heat resistant structural adhesive TRSA-5

[0050] Take 218.24g of γ-glycidyloxypropylmethyldimethoxysilane, 36.11g of dimethoxy(methyl)phenylsilane, 0.33g of hexamethyldimethoxysilane, 1.02g of tetramethylammonium hydroxide pentahydrate and 34.23g of deionized water and add them into a 500mL four-necked flask connected to a thermometer and a condenser, control the stirring paddle speed to 250r / min, and heat to 70°C; then connect nitrogen and react in a nitrogen environment for 1h; remove nitrogen, heat to 95°C, and react for 3h; distill under reduced pressure at -0.1MPa and 95°C for about 20min; wait until the system temperature drops to 40°C or room temperature, add 1g of acetic acid to remove the alkali, wait for 30min, and measure the pH value to 6-7. The obtained light yellow transparent viscous substance is methylphenyl epoxy modified silicone oil Ph-EpSO-5.

[0051] Take 5.33g of methylphenyl epoxy modified silicone oil Ph-EpSO-5, 4.25g of 170 type epoxy resin, 1.05g of curing agent dicyandiamide, 0.11g of RT-501 defoaming agent, and 0.21g of BYK leveling agent and mix them evenly. Use a wire rod to coat a 120μm thick heat-resistant structural adhesive on a copper sheet, then place it in a blast drying oven, set the temperature to 180℃, and cure it at this temperature for 20min to obtain the cured heat-resistant structural adhesive cured sheet TRSA-5.

[0052] Performance Testing

[0053] 1. Fourier transform infrared (FT-IR) test of methylphenyl epoxy modified silicone oil Ph-EpSO: Fourier transform infrared (FT-IR) test was performed on the methylphenyl epoxy modified silicone oil and raw materials in Examples 1-5 respectively, using an ALPHA-11 Fourier transform infrared spectrometer with a scanning range of 4000-600 cm -1 , resolution 4cm -1 , scanning times 16 times. The FT-IR test curves of epoxy modified silicone oil and raw materials with different -Ep / -Ph values ​​are shown in the figure. Figure 1 As shown, among which 3050cm -1 The C-H bond stretching vibration absorption peak of phenyl group is 2958 cm -1 、2870cm -1 The C–H bond stretching vibration absorption peak of Si–CH3 is 2933 cm -1 The C–H bond stretching vibration absorption peak of Si–CH2– and –CH2CH2– is 1590 cm -1 The C=C skeleton vibration absorption peak of phenyl group, 1429cm -1 The Si-Ph bond stretching vibration absorption peak of phenyl group connected to Si is 1259 cm -1 is the symmetrical stretching vibration absorption peak of Si–CH3, 1009 cm -1 The characteristic absorption peak of Si–O–Si is 906 cm -1 It is the symmetrical stretching vibration absorption peak of epoxy COC. It can be seen that the FT-IR curve of Ph-EpSO has obvious characteristic absorption peaks of phenyl, epoxy, silicon-oxygen bond and silicon methyl, indicating that Ph-EpSO has been successfully synthesized. -1 There is no obvious absorption peak nearby, indicating that the methoxy group (-OCH3) has reacted completely and no residue remains.

[0054] 2. NMR test of methylphenyl epoxy modified silicone oil Ph-EpSO: The methylphenyl epoxy modified silicone oils in Examples 1-5 were subjected to NMR tests respectively. At room temperature, deuterated chloroform (CDCl3) was used as the calibration solvent and the results were obtained by Bruker Avance III 400M nuclear magnetic spectrometer. 1 H NMR spectrum Figure 2 As shown, 1 H NMR (400 MHz, CDCl3): Chemical shift δ (ppm) = 7.31-7.51 (d, 5H, –Ph), 3.65-3.71 (s, 2H, –O–CH2–), 3.31-3.39 (d, 2H, –CH2–O–), 3.06-3.11 (s, 2H, –CH2–O–), 2.71-2.81 (m, 1H, ), 1.39~1.68(t, 2H, –CH2–), 0.47~0.52(s, 2H, Si–CH2–), 0.04~0.09(s, 3H, Si–CH3). It was proved that the five epoxy phenyl silicone oils all showed the methylene hydrogen proton peak on the epoxy group and the hydrogen proton peak of the phenyl group, indicating that the epoxy group and the phenyl group have been successfully introduced into Ph-EpSO. The obtained epoxy modified silicone oil Ph-EpSO with different -Ep / -Ph values 13 C NMR images Figure 3 As shown, the raw materials before the reaction 13 C NMR (101 MHz, CDCl3): δ (ppm) = -5.44, -5.12 (Si–CH3 of KH-562 and DMMPS), 1.33-1.38 (Si–O–CH3 of MM), 8.16 (Si–CH2– of KH-562), 23.98 (β-C of the ether group of KH-562), 43.62 (–O–CH2– on the epoxy group of KH-562), 50.51-50.97 (–O–CH3 of KH-562 and DMMPS), 70.08 (α-C of the epoxy group of KH-562), 73.36 (α-C of the ether group of KH-562), 127.96-134.03 (–Ph of DMMPS). Ph-EpSO after reaction 13C NMR (101 MHz, CDCl3): δ (ppm) = -0.97 (Si–CH3), 13.18 (Si–CH2–), 22.84 (ether group β-C), 43.97 (–O–CH2– on the epoxy group), 71.16, 73.73 (ether group α-C), 127.40-132.89 (–Ph). After the reaction, the Si–O–CH3 peak originally located at δ (ppm) = 50.51 essentially disappeared, and the Si–CH3 peaks at δ (ppm) = -5.12 and δ (ppm) = -5.44 shifted to δ (ppm) = -0.97, indicating that KH-562, DMMPS, and MM had been completely hydrolyzed and polycondensed to form a Ph-EpSO silicone oil structure.

[0055] 3. Physical properties test of methylphenyl epoxy modified silicone oil Ph-EpSO

[0056] (1) Epoxy value test: Mix analytical pure hydrochloric acid and acetone in a ratio of 1:24 (v / v), place in a brown glass reagent bottle and seal in the dark. Accurately weigh 0.5g of sample into a 250mL conical flask, use a pipette to accurately transfer 12.50mL of hydrochloric acid-acetone mixed reagent, and stir until the sample is completely dissolved. Then accurately add 5 drops of phenolphthalein indicator and titrate with 0.15mol / L sodium hydroxide standard solution. When the solution turns from colorless to light pink and the color remains stable for 15 seconds without fading, it is determined to be the titration end point. Calculate the epoxy value of the epoxy-terminated silicone oil according to formula 2.1. Repeat the measurement 3 times, take the average of the 3 measurements, and perform a blank experiment at the same time.

[0057]

[0058] Where: EV——epoxy value of epoxy-terminated silicone oil, mol / 100g;

[0059] C——concentration of sodium hydroxide standard solution, mol / L;

[0060] V0——the volume of sodium hydroxide standard solution consumed by blank sample, mL;

[0061] V——the volume of sodium hydroxide standard solution consumed by the sample, mL;

[0062] m——sample mass, g.

[0063] (2) Density test: Use QBB-37 density cup and measure according to ISO 2811.

[0064] (3) Viscosity test: NTV-S1 digital rotational viscometer was used and measured according to ISO 2555.

[0065] (4) Refractive index test: using a 2WA-J Abbe refractometer, measured in accordance with GB / T 14851-2018.

[0066] (5) UV-visible transmittance test: UVmini-1240 UV-visible spectrophotometer was used to measure the transmittance according to ASTM D1003-13.

[0067] The physical properties of the epoxy-modified silicone oils with different -Ep / -Ph values ​​in Examples 1-5 obtained by testing are shown in Table 1 below.

[0068] Table 1

[0069]

[0070] The five different -Ep / -Ph Ph-EpSO prepared in Examples 1-5 all had a molecular weight of 100,000. The appearance of the five groups of samples was as follows: Figure 4 As shown, all samples appeared as highly viscous, transparent liquids, with each group exhibiting a uniform, light yellow, transparent appearance. Table 1 also shows that the viscosity and density parameters did not exhibit significant gradient changes. At 25°C, the refractive index of Ph-EpSO ranged from 1.48 to 1.50, decreasing with increasing -Ep / -Ph values. This is related to the decrease in the phenyl content in the silicone oil as the -Ep / -Ph values ​​increase.

[0071] The UV-visible transmittances of the five Ph-EpSOs with different -Ep / -Ph ratios prepared in Examples 1-5 are as follows: Figure 5 As shown in the figure, Ph-EpSO-2 has the highest transmittance at 450nm, which is 92.13%. The transmittances at 450nm of the five silicone oils do not show a linear relationship, which may be due to residual catalyst or incomplete polycondensation.

[0072] 4. Performance test of heat-resistant structural adhesive TRSA

[0073] (1) Appearance: The heat-resistant structural adhesive TRSA-2 in Example 2 is applied to a 0.4 mm thick copper sheet. Figure 6 As shown in the figure, it can be seen that the heat-resistant structural adhesive TRSA-2 has good leveling properties on the copper sheet. It appears white and viscous after coating, and there is no obvious shrinkage on the surface of the film after standing.

[0074] (2) Thermal shock test: Figure 7 These are pictures of the heat-resistant structural adhesive cured sheets TRSA in Examples 1-5 at various stages. After undergoing 24 hot and cold shocks at -40°C to 140°C (-40°C*30min, 140°C*30min), the heat-resistant structural adhesive has a smooth surface without any cracks and good adhesion. Figure 8The bending morphology of the heat-resistant structural adhesive cured sheet TRSA in Examples 1-5 at each stage is shown. The heat-resistant structural adhesive TRSA-1 prepared with Ph-EpSO-1 as a precursor in Example 1 is bent 90° after 6 hot and cold shocks. There are a few inconspicuous cracks at the bend. After 12 and 24 hot and cold shocks, the cracks at the bend run through both sides of the copper sheet. This is because the phenyl content of Ph-EpSO-1 is relatively high, which causes the molecular chain rigidity to become stronger, making the adhesive surface show poor flexibility. The heat-resistant structural adhesives prepared with Ph-EpSO-3 in Example 3, Ph-EpSO-4 in Example 4, and Ph-EpSO-5 in Example 5 as precursors show different degrees of whitening at the bend after more than 6 hot and cold shocks. This may be because the phenyl content of these three silicone oils is relatively low, resulting in the heat resistance not reaching the actual use temperature. High temperature may cause the colloid to decompose or age, and stress concentration during bending may aggravate this change, resulting in whitening. The heat-resistant structural adhesive prepared using Ph-EpSO-2 as a precursor in Example 2 was bent without any cracking or whitening after undergoing 24 cycles of hot and cold shocks. Therefore, the heat-resistant structural adhesive prepared using Ph-EpSO-2 in Example 2 can meet the flexibility requirements of the product.

[0075] (3) TG test: The TG curves and TG data of the five heat-resistant structural adhesives in Examples 1-5 are shown in Figure 2. Figure 9 As shown in Table 2. Figure 9 As shown in Table 2, the T5% values ​​for TRSA-1, TRSA-2, TRSA-3, TRSA-4, and TRSA-5 are 235.64°C, 316.12°C, 304.52°C, 279.09°C, and 278.91°C, respectively; the T50% values ​​are 418.70°C, 437.38°C, 424.22°C, 433.91°C, and 419.79°C, respectively; and the Tmax values ​​are 412.35°C, 423.70°C, 409.22°C, 396.66°C, and 408.75°C, respectively. The residual rates for all TRSAs are above 18%, likely due to the high silicone content, thermal stability, and decomposition temperature. This indicates that TRSA-2's TG test results significantly outperform the other four TRSAs, demonstrating superior thermal stability.

[0076] Table 2

[0077]

[0078]

[0079] (5) DSC test: The DSC curves and DSC data of the five heat-resistant structural adhesives in Examples 1-5 are shown in Table 10 and Table 3, respectively. Figure 10As shown in Table 3, the five different TRSA curing products all exhibited a single glass transition temperature (Tg), with specific values ​​of 107.998°C, 113.320°C, 93.458°C, 71.033°C, and 79.323°C, respectively. This indicates that the TRSA system prepared based on Ph-EpSO exhibited no significant phase separation and good compatibility between the components. The Tg values ​​of the curing products generally showed a downward trend, which is related to the increase in the -Ep / -Ph ratio in the Ph-EpSO precursor. As the -Ep / -Ph ratio increases, the phenyl content in the system decreases, resulting in a decrease in the thermal stability of the TRSA curing products.

[0080] Table 3

[0081]

[0082] (6) Insulation Performance Analysis: Using the LK2672X withstand voltage tester, the heat-resistant structural adhesives were subjected to withstand voltage tests at the flat plate and the bend after curing, 6 rounds of hot and cold shock, 12 rounds of hot and cold shock, and 24 rounds of hot and cold shock. The breakdown current was set to 0.5 mA. Table 4 shows the withstand voltage test data of the heat-resistant structural adhesives prepared with different Ph-EpSO after 24 hot and cold shocks. After 24 hot and cold shocks, the withstand voltages at the flat plate of the heat-resistant structural adhesives prepared with 5 different silicone oils were almost the same. The heat-resistant structural adhesive prepared with Ph-EpSO-1 as the precursor cracked at the bend after 24 hot and cold shocks, and the withstand voltage could not be measured. After 24 thermal shock cycles, heat-resistant structural adhesives prepared with Ph-EpSO-3, Ph-EpSO-4, and Ph-EpSO-5 as precursors showed varying degrees of whitening at the bends. The heat-resistant structural adhesive prepared with Ph-EpSO-5 as a precursor showed the most pronounced whitening, resulting in significantly lower withstand voltage at the bends than the other heat-resistant structural adhesives. The heat-resistant structural adhesive prepared with Ph-EpSO-2 as a precursor exhibited the highest withstand voltage at the bends after 24 thermal shock cycles, effectively meeting product insulation requirements.

[0083] Table 4

[0084]

[0085]

[0086] (7) Other physical properties tests:

[0087] Pencil Hardness Test: In accordance with GB / T6739-2006, the specimen is rigidly fixed to the test platform using a dedicated fixture, ensuring the test surface is horizontal and free of deviation. A calibrated high-grade Zhonghua brand drawing pencil (compliant with standard hardness grading) is used. A pencil hardness tester is placed at a 45° angle to the specimen surface, applying a vertical load of 7.5N and moving the pencil at a constant speed of 5mm / s to create a continuous scratch. Using a hardness gradient method, the pencil grades are gradually increased from 6B to 9H. Each test is repeated three times. If damage is observed on the surface, the previous undamaged hardness grade is used as the final test result.

[0088] Flexibility test: The heat-resistant structural adhesive is bent to an angle of about R5, then bent flat, and repeated twice to see if cracking occurs to determine its flexibility.

[0089] Adhesion test: According to the adhesion test standard GB / T9286, use a grid cutter to form a grid on the coating surface, ensuring that each cut hits the substrate surface. Attach the tape to the cut grid and press firmly with your fingers or an eraser to ensure close contact between the tape and the coating. Quickly tear off the tape at the specified angle and observe any coating shedding. Determine the coating grade based on the area or degree of coating shedding, comparing it to the grade judgment table in the standard.

[0090] Pull-out test: A layer of epoxy structural adhesive was applied to the surface of a 1.6 cm diameter circular pure aluminum fixture and bonded together. The fixture was placed in a blast drying oven for curing, and then its pull-out strength was tested using a KJ-1066A tensile testing machine.

[0091] The physical properties of the heat-resistant structural adhesives prepared with different Ph-EpSO in Examples 1-5 after curing obtained from the tests are shown in Table 5 below.

[0092] Table 5

[0093]

[0094] As shown in Table 5, the heat-resistant structural adhesive prepared with Ph-EpSO-1 as a precursor is too rigid due to its high phenyl content, making it unable to effectively adhere to the substrate surface, resulting in poor adhesion and bonding performance. The heat-resistant structural adhesive prepared with Ph-EpSO-2 as a precursor achieves greater shear force and hardness, demonstrating relatively strong bonding and friction resistance. Therefore, choosing Ph-EpSO-2 as a precursor to prepare a heat-resistant structural adhesive can maximize the product's bonding performance and surface friction resistance.

[0095] The embodiments of the present invention are described in detail above, but the present invention is not limited to the described embodiments. It is apparent to those skilled in the art that various changes, modifications, substitutions, and variations of these embodiments may be made without departing from the principles and spirit of the present invention, and the changes still fall within the scope of protection of the present invention.

Claims

1. A method for preparing epoxy-modified silicone oil, characterized in that: The following steps are involved: (1) mixing γ-glycidyloxypropylmethyldimethoxysilane, dimethoxy(methyl)phenylsilane, hexamethyldimethoxysilane, tetramethylammonium hydroxide pentahydrate, and deionized water, stirring and heating the mixture under an inert gas environment; (2) After removing the inert gas, continue to heat the reaction; (3) distillation under reduced pressure, cooling, and then adding acetic acid dropwise to remove the base until the pH value is 6-7 to obtain epoxy-modified silicone oil.

2. The method for preparing an epoxy-modified silicone oil according to claim 1, wherein The molar ratio of the gamma-glycidyloxypropylmethyldimethoxysilane to dimethoxy(methyl)phenylsilane is 1:1 to 5:

1.

3. The method for preparing an epoxy-modified silicone oil according to claim 2, wherein: The molar ratio of the γ-glycidyloxypropylmethyldimethoxysilane to dimethoxy(methyl)phenylsilane is 2:

1.

4. The method for preparing an epoxy-modified silicone oil according to claim 1, wherein The mass of the tetramethylammonium hydroxide pentahydrate is 0.004 times the total mass of γ-glycidyloxypropylmethyldimethoxysilane, dimethoxy(methyl)phenylsilane and hexamethyldimethoxysilane.

5. The method for preparing an epoxy-modified silicone oil according to claim 1, wherein: The molar amount of the deionized water is 1.6 times the total molar amount of γ-glycidyloxypropylmethyldimethoxysilane and dimethoxy(methyl)phenylsilane.

6. An epoxy-modified silicone oil prepared by the preparation method according to any one of claims 1 to 4.

7. Use of the epoxy-modified silicone oil according to claim 5 in a heat-resistant structural adhesive, characterized in that: The preparation method of the heat-resistant structural adhesive comprises the following steps: uniformly mixing epoxy-modified silicone oil, epoxy resin, curing agent, defoaming agent and leveling agent, and heating and curing the mixture to obtain the cured heat-resistant structural adhesive.

8. The use of an epoxy-modified silicone oil in a heat-resistant structural adhesive according to claim 7, characterized in that: The molar ratio of the epoxy-modified silicone oil, epoxy resin and curing agent is 1:1:

1.

9. The use of an epoxy-modified silicone oil in a heat-resistant structural adhesive according to claim 7, characterized in that: The mass of the defoaming agent is 1% of the total mass of the epoxy modified silicone oil, the epoxy resin and the curing agent.

10. The use of an epoxy-modified silicone oil in a heat-resistant structural adhesive according to claim 7, characterized in that: The mass of the leveling agent is 2% of the total mass of the epoxy-modified silicone oil, the epoxy resin and the curing agent.

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