A modified silane coupling agent and its preparation method and application

Abstract

The present invention discloses a modified silane coupling agent, a preparation method, and an application thereof. The preparation method of the modified silane coupling agent is as follows: a rosin derivative and a silane coupling agent undergo a coupling reaction in an organic solvent, the reaction temperature is 0 to 50°C, and the reaction time is 10 to 100 minutes. The obtained modified silane coupling agent can be used to modify silicon nitride powder to obtain oil-based modified silicon nitride powder, which is ultimately used in the preparation of resin / silicon nitride composite materials. The present invention uses rosin derivatives as raw materials and is a bio-based green product that conforms to the concept of sustainable development; the synthesis method is simple, the conditions are mild, and industrial production is easy to achieve; through modification with the silane coupling agent, the silicon nitride powder has excellent organic phase dispersion properties.

Description

Technical Field

[0001] The present invention belongs to the technical field of silane coupling agents, and more specifically, relates to a modified silane coupling agent and a preparation method and application thereof. Background Art

[0002] As electronic technology evolves toward miniaturization and higher frequencies, the integration of electronic components continues to increase, leading to a sharp increase in their power consumption and heat generation. The resulting temperature rise significantly degrades the stability, reliability, and service life of electronic components, making heat dissipation a major constraint on the development of integrated circuits. Developing high-thermal-conductivity electronic packaging and thermal interface materials is one effective way to address this issue.

[0003] Polymer-based composites for electronic packaging and thermal interfaces often require the addition of inorganic fillers while maintaining their insulating properties, due to the low intrinsic thermal conductivity of organic polymers. Nitride ceramic powders are important high-thermal conductivity fillers due to their high thermal conductivity and electrical insulation properties. Compared to aluminum nitride and boron nitride, silicon nitride offers superior chemical stability and mechanical properties, holding significant application prospects.

[0004] Silicon nitride has two crystal forms, α and β. β-Si3N4 has a higher intrinsic thermal conductivity, reaching 320 W / m·K. Therefore, using β-Si3N4 as a thermally conductive filler is more advantageous. Silicon nitride is an inorganic substance with poor compatibility with organic matter. Direct use as a filler is prone to sedimentation, resulting in uneven thermal conductivity. It also has weak binding with the polymer organic phase, making it prone to phase separation, which affects the service life of the composite material. Currently, the more common method is to modify its surface with a silane coupling agent to improve its dispersion performance in the organic phase. However, commercial silane coupling agents have short alkyl chains, strong hydrophilicity, and poor hydrophobicity, resulting in poor dispersion in the organic phase. There is an urgent need to develop a new silane coupling agent with high organic dispersibility.

[0005] The main component of rosin is abietic acid, which accounts for approximately 90%. When heated to approximately 270°C and exposed to a catalyst, rosin is converted into disproportionated rosin, whose main component is dehydroabietic acid (approximately 40%). Rosin is then converted into hydrogenated rosin under the action of hydrogenation catalysts. These rosin chemical products are all naturally occurring chiral tricyclic diterpenoid compounds with stable properties. Each of these compounds contains 20 carbon atoms, only one of which is a polar carboxyl group; the others are non-polar groups. The overall structure is a compact, branched, oil-soluble group, resulting in high fat solubility and strong hydrophobicity. Furthermore, abietic acid contains two conjugated double bonds, which can undergo a Diels-Alder reaction with other double bonds. This allows it to covalently bond with other resin monomers containing double bonds or strained cycloalkanes during curing, enhancing its binding ability to the resin matrix.

[0006] For example, the Chinese patent application number is 202110518312.1, and the application publication date is August 13, 2021. It discloses a polyhydroxy rosin-modified organic silane coupling agent, its preparation method and its application. Due to the presence of polyhydroxy groups, the silane coupling agent can enhance the bonding properties of silicone rubber, but polyhydroxy groups also increase the hydrophilicity of this type of silane coupling agent, which is not suitable for the modification of silicon nitride thermal conductive fillers.

[0007] The Chinese patent application number is 202310570602.X, and the application publication date is October 10, 2023. It discloses the use of a highly active reactive rosin silicone resin. The rosin organosilane can be used as a sizing agent to improve the performance of paper-based materials. However, these silicone resins are synthesized by high-temperature reaction of low-reactivity rosin acid and silane coupling agent. During the synthesis, polymerization of the silane coupling agent will occur, and the reaction is incomplete, making it unsuitable as a modification of silicon nitride thermal conductive filler.

[0008] Therefore, there is an urgent need to develop a new dispersant that is simple to synthesize, has stable and reliable properties, and has high dispersion performance in the organic phase. Summary of the Invention

[0009] 1. Technical problem to be solved by the invention

[0010] To address the problems of poor dispersion and easy agglomeration of existing silicon nitride powder in organic phases, the present invention utilizes the characteristics of rosin groups as strongly lipophilic groups. Through a mild coupling reaction between rosin derivatives and silane coupling agents containing active groups, a rosin-modified silane coupling agent is developed. The rosin-modified silane coupling agent is used to modify silicon nitride powder to increase the lipophilicity of the silicon nitride powder and its dispersion effect in the organic phase, thereby enhancing the bonding strength between the silicon nitride and the resin matrix.

[0011] 2. Technical solution

[0012] In order to solve the above problems, the technical solutions adopted by the present invention are as follows:

[0013] A modified silane coupling agent, the general structural formula of the modified silane coupling agent is formula (I)

[0014] Where R1 is R2 is R3 is methyl or ethyl.

[0015] A preparation method of a modified silane coupling agent comprises the following steps: a rosin derivative and a silane coupling agent containing an active group undergo a coupling reaction in an organic solvent, the reaction temperature being 0-50° C. and the reaction time being 10-100 minutes.

[0016] Furthermore, the molar ratio of the rosin derivative, the silane coupling agent containing an active group and the organic solvent is 1:(0.8-1.2):(20-300).

[0017] Furthermore, an organic base is mixed into the modification reaction system.

[0018] Furthermore, the molar ratio of the rosin derivative to the organic base is 1:(0-10).

[0019] Furthermore, the organic base includes one, two or more of triethylamine, tri-n-propylamine, diisopropylethylamine, 1,4-diazabicyclo[2.2.2]octane, N-ethylpiperidine, N-ethylmorpholine and pyridine.

[0020] Furthermore, the rosin derivative includes dehydroabietin amine, dehydroabietin acyl chloride or abietic acid chloride.

[0021] Furthermore, the active group of the silane coupling agent containing an active group includes an amino group, a mercapto group, an epoxy group or an isocyanate group.

[0022] Furthermore, the silane coupling agent containing active groups includes but is not limited to γ-glycidyl ether propyl trimethoxy silane, β-(3,4-epoxycyclohexyl)ethyl trimethoxy silane, 3-isocyanate propyl triethoxy silane, γ-mercaptopropyl trimethoxy silane, and 3-aminopropyl triethoxy silane.

[0023] Furthermore, the organic solvent includes one, two or more of dichloromethane, chloroform, tetrachloromethane, 1,2-dichloroethane, tetrahydrofuran, ether, acetone, 1,4-dioxane, N,N-dimethylformamide, dimethyl sulfoxide, benzene, toluene, xylene, cyclohexane, n-hexane and petroleum ether.

[0024] A modified silicon nitride powder is obtained by modifying silicon nitride powder with the modified silane coupling agent. For example, the modified silane coupling agent can be hydrolyzed in a solution, then reacted with silicon nitride, and dried to obtain the modified silicon nitride powder.

[0025] The specific modification methods can be as follows:

[0026] The pH of a 95% ethanol (5% water) solution is adjusted to approximately 4.5-5.5 using acetic acid. The acidic ethanol solution, surface-activated silicon nitride powder, and modified silane coupling agent are then mixed in a mass ratio of 100:10:(0.1-0.2) and stirred under reflux for 10-60 minutes. The solvent is then evaporated and the mixture is dried in an oven at 50-130°C for 1-4 hours to obtain modified silicon nitride powder.

[0027] The method for surface activation of silicon nitride powder is as follows: silicon nitride powder is mixed with alkali, ball-milled, precipitated is filtered out, washed to neutrality, and naturally dried to obtain surface-activated silicon nitride powder.

[0028] Application of the above oil-based modified silicon nitride powder in the preparation of resin / silicon nitride composite materials.

[0029] 3. Beneficial effects

[0030] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0031] (1) The raw materials used in the rosin-modified silane coupling of the present invention are natural renewable resources, cheap and easily available, and the preparation method of the new silane coupling agent is simple and environmentally friendly.

[0032] (2) Rosin has large lipophilic groups, which can give silicon nitride powder excellent lipophilicity, obtain oil-based modified silicon nitride powder, and improve the dispersion performance of silicon nitride in the organic phase.

[0033] (3) Rosin can not only disperse inorganic powders, but its double-bonded derivatives can also add to resin monomers, making it compatible with curing resins and improving the bonding strength between the resin and silicon nitride powder. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 IR spectra of commercially available unmodified silicon nitride powder, modified silicon nitride powder O, and modified silicon nitride powder AE prepared in accordance with an embodiment of the present invention;

[0035] Figure 2 Shows photos of modified silicon nitride powder A (left) and modified silicon nitride powder O (right) dispersed in petroleum ether solution at different standing times;

[0036] Figure 3 This is a bar graph showing the thermal conductivity of the resin / silicon nitride composite material prepared in Example 7 of the present invention. DETAILED DESCRIPTION

[0037] For better understanding and implementation, the present invention is described in detail below with reference to embodiments. However, the protection scope of the present invention is not limited to these embodiments. Any changes or equivalent substitutions that do not deviate from the concept of the present invention are included in the scope of the present invention.

[0038] Example 1

[0039] Dehydroabietinamine (5.7 g, 20 mmol) was weighed and placed in a round-bottom flask, and anhydrous dichloromethane (30 mL, 468 mmol) was added to dissolve the mixture. γ-glycidyl ether propyltrimethoxysilane (4.7 g, 20 mmol) was then added. The mixture was reacted at 50° C. for 30 minutes, and the solvent was dried by spin drying to obtain modified silane coupling agent 1 (10.4 g, 98% yield).

[0040] NMR of product 1: 1 H NMR(400MHz, CDCl3)δ7.17(br,1H),7.00(br,1H),6.88(br,1H),5.37(s,1H),3.70(s,1H),3.55(s,9H), 3.34-3.80(m,5H),2.50-2.90(m,5H),2.25-2.50(m,1H),1.10-2.20(m,21H),0.94(s,3H),0.56(t,2H). Mass spectrum: HRMS((+)-ESI): m / z=522.3609(calcd.522.3615for[C 29 H 52 NO5Si][M+H] + ).

[0041] The reaction formula is as follows:

[0042]

[0043] Example 2

[0044] Dehydroabietinamine (5.7 g, 20 mmol) was weighed and placed in a round-bottom flask, and anhydrous tetrahydrofuran (30 mL, 370 mmol) was added to dissolve the mixture. β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (3.9 g, 16 mmol) was then added. The mixture was reacted at 50° C. for 60 min, and the solvent was dried by spin drying. The mixture was washed with a small amount of petroleum ether to obtain modified silane coupling agent 2 (8.0 g, yield 94%).

[0045] NMR of product 2: 1 H NMR(400MHz, CDCl3)δ7.18(br,1H),6.94(br,1H),6.86(br,1H),3.41(s,9H),3.00-3.30(m ,3H),2.75-2.92(m,3H),2.25-2.60(m,3H),1.10-2.20(m,27H),0.94(s,3H),0.56(t,2H). Mass spectrum: HRMS((+)-ESI):m / z=532.3820(calcd.532.3822for[C 31 H 54NO4Si][M+H] + ).

[0046] The reaction formula is as follows:

[0047]

[0048] Example 3

[0049] Dehydroabietinamine (5.7 g, 20 mmol) was weighed and placed in a round-bottom flask. Anhydrous 1,2-dichloroethane (40 mL, 509 mmol) was added to dissolve the mixture. 3-isocyanatepropyltriethoxysilane (5.9 g, 24 mmol) was then added. The mixture was reacted at room temperature for 120 minutes. The solvent was then dried and washed with a small amount of petroleum ether to obtain modified silane coupling agent 3 (10.0 g, yield 94%).

[0050] NMR of product 3: 1 H NMR(400MHz, CDCl3)δ7.14(br,1H),6.96(br,1H),6.86(br,1H),3.72(q,6H),3.38(t,2H),2.7 9-3.16(m,5H),1.30-2.20(m,14H),1.24(t,9H),1.00-1.20(m,8H),0.94(s,3H),0.56(t,2H). Mass spectrum: HRMS((+)-ESI): m / z=533.3778(calcd.533.3775for[C 30 H 53 N2O4Si][M+H] + ).

[0051] The reaction formula is as follows:

[0052]

[0053] Example 4

[0054] Abietic acid (6 g, 20 mmol) was weighed and added to a 250 mL round-bottom reaction flask. Anhydrous dichloromethane (40 mL) was added to dissolve it. The mixture was evacuated and filled with nitrogen three times. After 5 minutes of ice-water bath, oxalyl chloride (5.1 mL, 60 mmol) and 0.1 mL of anhydrous DMF were injected. The ice-water bath was removed and the reaction was carried out at room temperature for 12 hours. The solvent and oxalyl chloride were then evaporated under reduced pressure to obtain abietic acid chloride.

[0055] Abietic acid chloride (6.4 g, 20 mmol) was weighed and placed in a round-bottom flask, followed by the addition of anhydrous dichloromethane (30 mL, 468 mmol) to dissolve the mixture. γ-mercaptopropyltrimethoxysilane (3.9 g, 20 mmol) and triethylamine (8.3 mL, 60 mmol) were then added under an ice-water bath. The mixture was reacted at room temperature for 30 minutes, the resulting salt was filtered off, and the solvent was dried to obtain modified silane coupling agent 4 (9.2 g, 96% yield). It should be noted that the reaction in this example is highly exothermic, and high temperatures can easily produce by-products, so an ice-water bath was used.

[0056] NMR of product 4: 1 H NMR (400 MHz, CDCl3) δ 5.76 (s, 1H), 5.50 (t, 1H), 3.55 (s, 9H), 2.85 (t, 2H), 2.32-2.42 (m, 3H), 1.90-2.20 (m, 5H), 1.12-1.90 (m, 9H), 1.27 (s, 3H), 1.12 (s, 3H), 0.86 (d, 6H), 0.56 (t, 2H). Mass spectrum: HRMS ((+)-ESI): m / z = 481.2810 (calcd. 481.2808 for [C 26 H 45 O4SSi][M+H] + ).

[0057] The reaction formula is as follows:

[0058]

[0059] Example 5

[0060] Abietic acid chloride (6.4 g, 20 mmol) was weighed and placed in a round-bottom flask, followed by dissolution in anhydrous chloroform (30 mL, 468 mmol). 3-Aminopropyltriethoxysilane (4.4 g, 20 mmol) and tri-n-propylamine (5.7 mL, 30 mmol) were then added under an ice-water bath. The mixture was reacted at room temperature for 30 minutes, the resulting salt was filtered off, and the solvent was dried to obtain modified silane coupling agent 5 (8.7 g, 95% yield). It should be noted that the reaction in this example is highly exothermic, and high temperatures can easily produce by-products, so an ice-water bath was used.

[0061] NMR of product 5: 1H NMR(400MHz, CDCl3)δ8.01(s,1H),5.75(s,1H),5.50(t,1H),3.70(q,6H),3.18(t,2H),2.30-2.45(m, 3H),1.92-2.22(m,5H),1.12-1.91(m,9H),1.21(t,9H),1.00-1.12(m,5H),0.86(d,6H),0.56(s,2H). Mass spectrum: HRMS((+)-ESI): m / z=505.3590(calcd.505.3587for[C 29 H 51 NO4Si][M+H] + ).

[0062] The reaction formula is as follows:

[0063]

[0064] Example 6

[0065] Ailan (Shanghai) Chemical Technology Co., Ltd.'s silicon nitride powder has a β-phase content of 99.9% and an average particle size of 1-3 μm. To increase the surface hydroxyl content of the powder, the powder was mixed with a 0.5% sodium hydroxide solution in a volume ratio of 1:4, with a material-to-ball ratio of 1:1. The mixture was ball-milled at 400 rpm for 12 hours. The precipitate was filtered, washed with deionized water until neutral, and air-dried to obtain surface-activated silicon nitride powder.

[0066] The pH of a 95% ethanol (5% water) solution was adjusted to approximately 4.5-5.5 using acetic acid. The acidic ethanol solution, the surface-activated silicon nitride powder, and modified silane coupling agent 1 were then mixed in a mass ratio of 100:10:0.2, stirred, and refluxed for 6 hours. The mixture was then filtered, and the solid was washed with ethanol and dried in an oven at 120°C for two hours to obtain modified silicon nitride powder A.

[0067] Under the same conditions, modified silane coupling agent 2, modified silane coupling agent 3, modified silane coupling agent 4, and modified silane coupling agent 5 were used to obtain modified silicon nitride powder B, modified silicon nitride powder C, modified silicon nitride powder D, and modified silicon nitride powder E, respectively. In addition, for comparison, modified silicon nitride powder O was also prepared under the same conditions using the commercial silane coupling agent KH560.

[0068] Figure 1 The infrared spectra of commercially available unmodified silicon nitride powder, modified silicon nitride powder O and modified silicon nitride powder AE prepared in the embodiment of the present invention are shown in FIG. Figure 1 It can be seen that the infrared spectrum of silicon nitride powder AE appears at 2960cm-1 The methyl absorption peak near the rosin group is not found in the commercially available unmodified silicon nitride powder and modified silicon nitride powder O. This indicates that the rosin group has been successfully connected to the surface of the silicon nitride particles because only the rosin group has a methyl group.

[0069] Figure 2 The following pictures show the petroleum ether solution of modified silicon nitride powder A and modified silicon nitride powder O prepared with a mass fraction of 0.1% at different standing times. Figure 2 It can be seen that after 1 day, the modified silicon nitride powder O was basically completely precipitated in the solution, while the modified silicon nitride powder A had only a small amount of precipitation in the solution, indicating that the rosin-based modification significantly improved the dispersion performance of silicon nitride in organic solvents.

[0070] Example 7

[0071] In order to evaluate the actual use effect of the modified silicon nitride powder, divinylsiloxane-bisbenzocyclobutene resin monomer was added to a three-necked flask, and the modified silicon nitride powder O with a mass fraction of 50% was added to the resin monomer. Then, defoaming agent, surfactant and other additives were added in sequence. After stirring evenly, it was quickly poured into a mold, heated to 100 ° C and vacuum degassed for 1 hour, and then heated to above the curing temperature and cured completely to obtain the resin / silicon nitride composite material S. O .

[0072] The modified silicon nitride powder AE prepared in the embodiment of the present invention is prepared according to the above steps to obtain a resin / silicon nitride composite material S A -S E .

[0073] Figure 3 This is a bar graph of the thermal conductivity of the resin / silicon nitride composite material obtained in Example 7 of the present invention. Figure 3 The thermal conductivity results of each resin / silicon nitride composite material show that among the resin / silicon nitride composite materials with high silicon nitride content, the composite material prepared with commercial silane coupling agent (resin / silicon nitride composite material S O ), the thermal conductivity of the bottom and upper parts are 0.87 and 0.77 W / m·K respectively, which are quite different. This is because the modified silicon nitride powder O has poor dispersion in oil and is deposited during the curing process. The resin / silicon nitride composite material S prepared by the embodiment of the present invention A -S E The thermal conductivity of each part tends to be consistent, indicating that the powder has better dispersion performance. The thermal conductivity is between 1.05 and 1.09 W / m·K, which is better than that of the resin / silicon nitride composite material S OThe thermal conductivity of the cyclobutene group will be combined with the rosin group containing double bonds during the heating ring-opening polymerization process, further improving the bonding strength between the resin and the silicon nitride powder, thus S D and S E The thermal conductivity of is the highest, which is 1.08 and 1.09 W / m·K respectively.

[0074] The above embodiments have elaborated on the purpose and implementation effects of the present invention in detail. It should be understood that the above embodiments are merely descriptions of the preferred embodiments of the present invention, and do not limit the concept and scope of the present invention. All modifications, equivalent substitutions, improvements, etc. made by engineers and technicians in this field or using the technical concepts and technical solutions of the present invention within the spirit and principles of the present invention and without departing from the design ideas of the present invention are within the scope of protection of the present invention.

Claims

1. A modified silane coupling agent, characterized in that: The general structural formula of the modified silane coupling agent is the following formula (I): Wherein, R3 is methyl or ethyl; R2 is or When R1 is 、 、 or ; or; R2 is When R1 is or ; or; R2 is When R1 is 、 、 or .

2. A method for preparing the modified silane coupling agent according to claim 1, characterized in that: The method comprises the following steps: a rosin derivative and a silane coupling agent containing an active group undergo a coupling reaction in an organic solvent, the reaction temperature being 0-50° C. and the reaction time being 10-100 minutes; The active group is selected from amino, thiol, epoxy and isocyanate groups, and the rosin derivative is dehydroabietinamine, dehydroabietin acyl chloride or rosin acid chloride.

3. The method for preparing a modified silane coupling agent according to claim 2, wherein: The molar ratio of the rosin derivative to the silane coupling agent is 1:(0.8-1.2).

4. The method for preparing a modified silane coupling agent according to claim 3, wherein: An organic base is also mixed in the reaction system.

5. The method for preparing a modified silane coupling agent according to claim 4, wherein The molar ratio of the rosin derivative to the organic base is 1: (0-10).

6. The method for preparing a modified silane coupling agent according to claim 4, wherein: The organic base is one, two or more of triethylamine, tri-n-propylamine, diisopropylethylamine, 1,4-diazabicyclo[2.2.2]octane, N-ethylpiperidine, N-ethylmorpholine and pyridine.

7. The method for preparing a modified silane coupling agent according to any one of claims 2 to 6, wherein: The organic solvent is one, two or more of dichloromethane, chloroform, tetrachloromethane, 1,2-dichloroethane, tetrahydrofuran, ether, acetone, 1,4-dioxane, N,N-dimethylformamide, dimethyl sulfoxide, benzene, toluene, xylene, cyclohexane, n-hexane and petroleum ether.

8. A modified silicon nitride powder, characterized in that: The modified silicon nitride powder is obtained by modifying the silicon nitride powder with the modified silane coupling agent according to claim 1.

9. Use of the modified silicon nitride powder according to claim 8 in the preparation of resin / silicon nitride composite materials.

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