Amine modified oligomer cross-linked epoxy resin material, preparation method and application

Abstract

The invention discloses a preparation method of an amine-modified oligomer cross-linked epoxy resin material. The preparation method comprises the following steps: (1) preparing a colloid of triethylamine-terminated inorganic ion oligomer and ethanol by adopting a liquid-phase acid-base neutralization method; (2) dispersing the triethylamine-terminated inorganic ion oligomer obtained in the step (1) and ethanol colloid in a liquid amine curing agent, and heating to prepare an amine-modified inorganic ion oligomer / amine curing agent solution; and (3) mixing the amine modified inorganic ion oligomer / amine curing agent solution with epoxy resin, and curing to obtain the epoxy resin composite material. A calcium phosphate oligomer is subjected to amino functional modification, so that the calcium phosphate oligomer can directly participate in a cross-linking reaction of epoxy resin, a hybrid material with a molecular-level organic-inorganic interface is formed, the mechanical strength and toughness of a resin material are enhanced, and meanwhile, the electrical insulation property is improved; and wide application prospects are shown in the fields of high-voltage insulation towers, electrical equipment, power electronic packaging and the like.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to an amine-modified oligomer crosslinked epoxy resin material, its preparation method, and its application. Background Technology

[0002] Polymers are widely used as insulating frameworks in high-voltage electrical equipment. Epoxy resins, due to their inherent electrical insulation, mechanical strength, chemical resistance, and thermal stability, have become one of the most widely used materials in electrical engineering, covering areas such as transformer potting, power electronic encapsulation, and composite towers. In recent years, the trend of power systems moving towards ultra-high voltage, large capacity, and miniaturization has placed higher demands on the performance of epoxy resins. How to simultaneously improve the electrical and mechanical properties of epoxy resins through modification has always been a hot topic and a challenge in electrical engineering materials research.

[0003] Adding inorganic nanoparticles (such as nano-alumina, nano-clay, boron nitride nanosheets, and silica nanoparticles) is a common method for optimizing the electrical insulation properties of epoxy resins. Chinese patent document CN116814044A discloses a method for preparing and applying epoxy resin composite insulating materials modified with positive temperature coefficient inorganic ceramic (PTC) fillers. This material is obtained by curing an epoxy resin system and doped core-shell structured PTC particles. The core-shell structured PTC particles include ceramic fillers and boron nitride nanoparticles bonded to the ceramic fillers by polydopamine. Chinese patent document CN109943021A discloses a method for modifying epoxy resin composite materials with nano-inorganic fillers. This method utilizes a high-voltage micronization device (used for micron-level particle nano-sizing) to disperse the inorganic fillers in epoxy resin liquid, significantly improving the performance of the composite material by addressing the problem of easy agglomeration of nanoparticles due to their high surface efficiency, and greatly enhancing the dispersibility of the inorganic fillers in the epoxy resin.

[0004] The principle behind the aforementioned modification strategy lies in the fact that the formation of the organic-inorganic interface / junction introduces a Fermi level difference (between the organic and inorganic phases), thereby enhancing the electrical insulation properties of the material. However, due to the inherent differences in mechanical properties between the inorganic and organic phases, interface defects and structural discontinuities are easily caused. Furthermore, when inorganic fillers are blended with epoxy resin, filler agglomeration is often a problem, which not only reduces the modification effect but may also degrade the original mechanical flexibility of the material.

[0005] Therefore, although increasing the content of inorganic fillers can improve electrical insulation and stiffness, it also increases the brittleness of the material and reduces its elongation at break, making the design of high-performance epoxy resins face the challenge of balancing electrical insulation and mechanical toughness. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a method for preparing an epoxy resin material crosslinked with amine-modified oligomers. The method involves amine-functionalizing inorganic ionic oligomers, enabling them to directly participate in the crosslinking reaction of epoxy resin, forming a hybrid material with a molecular-level organic-inorganic interface. In this material, the molecular-scale inorganic ionic oligomers enhance the mechanical strength and toughness of the resin matrix through quantum size effects, while simultaneously improving electrical insulation properties. The resulting composite material shows broad application prospects in high-voltage insulating towers, electrical equipment insulation, and power electronic packaging.

[0007] A method for preparing an amine-modified oligomer crosslinked epoxy resin material includes the following steps: (1) Triethylamine-terminated inorganic ionic oligomers and ethanol colloids were prepared by liquid-phase acid-base neutralization method; (2) The triethylamine-terminated inorganic ionic oligomer and ethanol obtained in step (1) are dispersed in a liquid amine curing agent and heated to prepare an amine-modified inorganic ionic oligomer / amine curing agent solution. (3) The amine-modified inorganic ionic oligomer / amine curing agent solution obtained in step (2) is mixed with epoxy resin and cured to obtain epoxy resin composite material.

[0008] In this invention, the boiling point difference between liquid amine curing agents and triethylamine is utilized. A heating reaction is performed between the liquid amine curing agent and triethylamine-terminated inorganic ionic oligomers, replacing the triethylamine-terminated inorganic ionic oligomers with amine-modified inorganic ionic oligomers. The heating reaction also causes the ethanol and triethylamine in the reaction system to volatilize, thus preventing the presence of ethanol and triethylamine from affecting the thermal properties (glass transition temperature) of the epoxy resin composite material. T g The temperature drops by about 4°C, and the electrical insulation properties (conductivity increases by about an order of magnitude) also decrease.

[0009] Compared to triethylamine-terminated inorganic ionic oligomers, amine-terminated inorganic ionic oligomers exhibit superior stability, maintaining uniform dispersion in amine curing agents for extended periods without sedimentation or deterioration even after storage exceeding one year. Furthermore, by selecting different types of amines for end-capping modification, good compatibility with various epoxy resin systems can be achieved, effectively improving the electrical insulation and mechanical properties of epoxy resins without introducing exogenous impurities such as alcohol or triethylamine. Because the modified amine-terminated inorganic ionic oligomers possess amine terminals, they can be directly mixed and crosslinked with epoxy resins, solving the problems of poor dispersibility, easy aggregation, and weak interfacial interactions inherent in traditional inorganic nanofillers.

[0010] This invention improves the performance of composite materials by crosslinking amine-modified inorganic ionic oligomers with epoxy resin, leveraging the high specific surface area and high reactivity of the oligomers. On one hand, hydrogen bonding exists between the inorganic ionic oligomers and the modified amino groups, enhancing their compatibility and dispersibility within the epoxy resin matrix. On the other hand, the oligomers themselves provide stiffness and strength support to the composite material, thereby enhancing its mechanical properties and toughening. Furthermore, the energy level difference between the inorganic ionic oligomers and the epoxy resin can form a charge barrier, increasing the number of epoxy resin traps and improving the insulation strength of the epoxy resin composite material, ultimately achieving a synergistic improvement in both the electrical insulation and mechanical toughness of the epoxy resin.

[0011] Preferably, in step (1), the inorganic ionic oligomer is at least one of calcium phosphate oligomer, calcium carbonate oligomer, and calcium sulfate oligomer.

[0012] Preferably, in step (1), the specific steps of the liquid-phase acid-base neutralization method include: using triethylamine as a capping agent, adding a cation source and an anion source to ethanol, reacting at room temperature to obtain a triethylamine-capped inorganic ionic oligomer, and washing with ethanol to obtain a triethylamine-capped inorganic ionic oligomer and an ethanol colloid.

[0013] More preferably, when the inorganic ionic oligomer is a calcium phosphate oligomer, the cation source is a calcium salt and the anion source is phosphoric acid; When the inorganic ionic oligomer is a calcium carbonate oligomer, the cation source is a calcium salt and the anion source is carbon dioxide. When the inorganic ionic oligomer is a calcium sulfate oligomer, the cation source is a calcium salt and the anion source is sulfuric acid.

[0014] More preferably, the molar ratio of triethylamine to the cation in the cation source is 19-25:1; and the volume ratio of triethylamine to the anion source is 50-60:1.

[0015] Preferably, in step (2), the liquid amine curing agent is one of polyetheramine, diethylenetriamine, triethylenetetramine, ethylenediamine, 3-diethylaminopropylamine, m-xylenediamine, and o-aminophenoxyethylamine.

[0016] In this invention, it is necessary to ensure that the boiling point of the selected liquid amine curing agent is higher than that of triethylamine (90°C).

[0017] More preferably, the liquid amine curing agent is a polyetheramine, and the molecular weight of the polyetheramine is 230~2000.

[0018] Preferably, in step (2), the mass ratio of the amine curing agent to the triethylamine-terminated inorganic ionic oligomer and the ethanol colloid is 3~15:1.

[0019] Preferably, in step (2), the heating temperature is ≥60 ℃ and lower than the boiling point of the liquid curing agent.

[0020] Preferably, in step (3), the proportion of amine-modified inorganic ionic oligomers in the epoxy resin composite material is 0.1~0.5wt%.

[0021] In this invention, the amine-modified inorganic ionic oligomers in the epoxy resin composite material are calculated using the following formula: .

[0022] In this invention, amine-modified inorganic ionic oligomers can fully crosslink with epoxy resin, which is beneficial for achieving optimal mechanical strength and toughness in epoxy resin composites. If the content of amine-modified inorganic ionic oligomers is too low, fewer inorganic ionic oligomers will crosslink with the epoxy resin, resulting in limited improvement in stiffness and toughness. If the content of amine-modified inorganic ionic oligomers is too high, the inorganic ionic oligomers will fuse, increasing the modulus but decreasing toughness and strength. Therefore, the inorganic ionic oligomer content within the aforementioned range ensures that the epoxy resin composite material possesses high mechanical strength and toughness.

[0023] More preferably, the proportion of inorganic ionic oligomers in the epoxy resin composite material is 0.1~0.4wt%.

[0024] More preferably, the proportion of inorganic ionic oligomers in the epoxy resin composite material is 0.2 wt%.

[0025] Preferably, in step (3), the curing temperature is 80~125 ℃ and the curing time is 7~8 h.

[0026] More preferably, the curing process involves first curing at 80°C for 1 hour, then raising the temperature to 125°C for 6-7 hours.

[0027] The present invention also provides an epoxy resin composite material prepared by the above preparation method.

[0028] Preferably, the epoxy resin composite material has a mechanical strength of 128~140 MPa and a mechanical toughness of 7~10 MJ / m. 3 The insulation breakdown strength is 100~120 kV / mm.

[0029] This invention achieves good compatibility with various epoxy resin systems by using different types of amine curing agents to end-cap inorganic ionic oligomers. This effectively improves the electrical insulation and mechanical properties of epoxy resins without introducing exogenous impurities such as ethanol and triethylamine. Furthermore, compared with existing techniques that directly crosslink inorganic ionic oligomers with epoxy resins, the epoxy resin composite material obtained by this invention exhibits superior thermal properties (e.g., ...). T g The electrical properties showed no deterioration and had significant advantages.

[0030] The present invention also provides the application of the above-mentioned epoxy resin material in the fields of power system insulating towers, insulating crossarms, cable joint potting compounds, and electronic packaging.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows: Amine functionalization of calcium phosphate oligomers enables them to directly participate in the crosslinking reaction of epoxy resins, forming hybrid materials with molecular-level organic-inorganic interfaces. This enhances the mechanical strength and toughness of the resin materials while improving their electrical insulation properties, showing broad application prospects in high-voltage insulating towers, electrical equipment insulation, and power electronic packaging. Attached Figure Description

[0032] Figure 1 This is a schematic diagram illustrating the principle of preparing epoxy resin composite materials according to the present invention.

[0033] Figure 2 The comparison is between the polyetheramine-modified inorganic calcium phosphate oligomer / polyetheramine solution prepared in step (3) of Example 1 and the solution after standing for 1 year.

[0034] Figure 3 The image shows a comparison of the polyetheramine-modified inorganic calcium phosphate oligomer / polyetheramine solution prepared in step (3) of Example 1 and the hydroxyapatite / polyetheramine solution obtained in step (1) of Comparative Example 2 before and after standing for 1 month.

[0035] Figure 4 Optical images of the epoxy resin composite materials prepared in Example 1, Comparative Examples 1, 2 and 3.

[0036] Figure 5 The diagram shows a comparison of the Weibull distribution of insulation breakdown of the epoxy resin composite materials prepared in Example 1, Comparative Examples 1, 2 and 3.

[0037] Figure 6 This is a comparison diagram of the conductivity current density of the epoxy resin composite materials prepared in Example 1, Comparative Examples 1, 2 and 3 under different electric fields.

[0038] Figure 7The bending stress-strain curves are for the epoxy resin composite materials prepared in Example 1, Comparative Examples 1, 2 and 3.

[0039] Figure 8 The epoxy resin composite materials prepared in Example 1, Comparative Examples 1, 2 and 3 T g Test image.

[0040] Figure 9 This is a schematic diagram illustrating application scenarios for epoxy resin composite materials. Detailed Implementation

[0041] The present invention will be further described in detail below with reference to the embodiments, but the implementation of the present invention is not limited to the following embodiments.

[0042] All raw materials used in this invention are commercially available.

[0043] Figure 1 This is a schematic diagram illustrating the mechanism for preparing epoxy resin composite materials according to the present invention. In this diagram, AP represents polyetheramine, CPO represents calcium phosphate oligomer, CaP-EP represents epoxy resin composite material with added calcium phosphate, HA-EP represents epoxy resin composite material with added 50 nm hydroxyapatite, Pure EP represents pure epoxy resin, and uCaP-EP represents material obtained by directly mixing and curing untreated and modified CPO with a curing agent and epoxy resin. The epoxy resin composite material modified with molecular-scale inorganic ionic compounds can be prepared into various shapes.

[0044] Example 1 (1) Triethylamine-terminated calcium phosphate oligomers and ethanol colloids were prepared by liquid-phase acid-base neutralization method. First, 17.64 g of CaCl2·2H2O was dissolved in 2.40 L of ethanol to obtain a clear alcohol solution. Then, 332.69 mL of TEA was added to the above solution under magnetic stirring at 25 °C, and stirring was continued for 30 min. Next, an alcohol solution of H3PO4 (i.e., 6.27 mL of H3PO4 dissolved in 120 mL of ethanol) was added to the system under vigorous stirring, and the reaction was carried out at 25 °C for 12 h. After the reaction was completed, the precipitate was obtained by centrifugation at 6000 rpm and washed three times with ethanol to remove excess TEA, thus obtaining triethylamine-terminated inorganic ionic oligomers and ethanol colloids.

[0045] (2) Dissolve 4.6 g of the triethylamine-terminated calcium phosphate oligomer obtained in step (1) and the colloid of ethanol (the content of calcium phosphate oligomer in the colloid was 5.8% by thermogravimetric analysis, i.e., 0.267 g of calcium phosphate oligomer) in 33.3 g of polyetheramine with a molecular weight of 230 (purchased from Huntsman Company, catalog number polyetheramine D230). Sonicate the solution for 5 minutes by ultrasonic dispersion to obtain a calcium phosphate oligomer / polyetheramine solution containing polyetheramine modification. (3) The mixture of calcium phosphate, ethanol, triethylamine, and polyetheramine obtained in step (2) is heated at 60 °C for 12 h to remove excess triethylamine, alcohol, and other impurities. A small amount of polyetheramine will also volatilize during the heating process, so polyetheramine needs to be added to the remaining solution to restore it to its original mass before heating; Figure 2 and Figure 3 As shown, after being left for 1 month or even 1 year, the mixed solution did not precipitate or change color; (4) The polyetheramine curing agent containing polyetheramine-modified calcium phosphate oligomers obtained in step (3) is mixed with 100 g of bisphenol A diglycidyl ether, and the mixture is mechanically stirred at 40 °C for 15 minutes. Then, the homogeneous solution is degassed in a vacuum oven for 30 minutes; The mixture was poured into a mold and cured at 80 °C for 1 hour, then at 125 °C for 6 hours to obtain an epoxy resin composite material (CaP-EP), wherein the content of amine-modified calcium phosphate oligomers was 0.2 wt%. The composite material can be obtained in different shapes depending on the mold used, such as... Figure 4 As shown. The obtained circular strips with a diameter of 6 cm and a thickness of 0.2 mm were used for electrical testing. The dimensions of the bending and tensile specimens met the requirements of GB / T 1040-2018 "Determination of Tensile Properties of Plastics".

[0046] The test results of the epoxy resin material prepared in Example 1 are as follows: Figures 5-8 As shown, its breakdown strength is 116.7 kV / mm, its mechanical bending strength reaches 136.9 MPa, its mechanical modulus reaches 3.87 GPa, and its mechanical toughness reaches 8.85 MJ / m. 3 Obtained through dynamic thermomechanical measurements (DMA) T g It is 97.4 ℃.

[0047] Example 2 The preparation method was the same as in Example 1, except that the amount of triethylamine-terminated calcium phosphate oligomer and ethanol colloid added was 2.3 g (containing 0.134 g of calcium phosphate oligomer). The resulting epoxy resin composite material contained 0.1 wt% amine-modified calcium phosphate oligomer, exhibiting a breakdown strength of 100.8 kV / mm, a flexural strength of 131.3 MPa, a mechanical modulus of 3.59 GPa, and a mechanical toughness of 7.11 MJ / m. 3 .

[0048] Example 3 The preparation method was the same as in Example 1, except that the amount of triethylamine-terminated calcium phosphate oligomer and ethanol colloid added was 9.2 g (containing 0.534 g of calcium phosphate oligomer). The resulting epoxy resin composite material contained 0.4 wt% amine-modified calcium phosphate oligomer, exhibiting a breakdown strength of 108.4 kV / mm, a flexural strength of 128.6 MPa, a mechanical modulus of 3.88 GPa, and a mechanical toughness of 7.14 MJ / m. 3 .

[0049] Comparative Example 1 33.3 g of polyetheramine with a molecular weight of 230 was mixed with 100 g of bisphenol A diglycidyl ether, and the mixture was mechanically stirred at 40 °C for 15 minutes. Subsequently, the homogeneous solution was degassed in a vacuum oven for 30 minutes, and then cast into the mold to obtain pure epoxy resin (Pure EP), which served as a control material. Its breakdown strength was only 95.6 kV / mm, its mechanical flexural strength was only 98.3 MPa, its mechanical modulus was only 2.95 GPa, and its mechanical toughness was only 6.61 MJ / m. 3 Obtained through DMA T g It is 96.5 ℃.

[0050] Comparative Example 2 (1) Mix 0.267 g of hydroxyapatite with a particle size of 50 nm with 33.3 g of polyetheramine with a molecular weight of 230, stir for 15 minutes, and then ultrasonically disperse for 5 minutes; Figure 3 As shown, a significant precipitate can be observed after the mixed solution has been left for one month. (2) The ultrasonically dispersed polyetheramine mixture was mixed with 100 g of bisphenol A diglycidyl ether, and the mixture was mechanically stirred at 40 °C for 15 minutes. Subsequently, the homogeneous solution was degassed in a vacuum oven for 30 minutes, and then cast into the mold to obtain the HA-EP composite material, which served as a control material (i.e., HA-EP). Figure 4As shown, its breakdown strength is 102.1 kV / mm, its mechanical bending strength is only 101.8 MPa, its mechanical modulus is only 3.32 GPa, and its mechanical toughness is only 5.10 MJ / m. 3 Obtained through DMA T g It is 97.5 ℃.

[0051] Comparative Example 3 (1) 4.6 g of the triethylamine-terminated calcium phosphate oligomer obtained in step (1) of Example 1 and the colloid of ethanol (containing 0.267 g of calcium phosphate oligomer) were mixed with 33.3 g of polyetheramine with a molecular weight of 230 and stirred for 15 minutes, and then ultrasonically dispersed for 5 minutes to obtain a calcium phosphate oligomer polyetheramine solution containing ethanol and triethylamine impurities; (2) The dispersed polyetheramine mixture was mixed with 100 g of bisphenol A diglycidyl ether, and the mixture was mechanically stirred at 40 °C for 15 minutes. Subsequently, the homogeneous solution was degassed in a vacuum oven for 30 minutes, and then cast into the mold to obtain the uCaP-EP composite material, which served as a control material. Its breakdown strength was 104.7 kV / mm, its mechanical flexural strength was 119.5 MPa, its mechanical modulus was 3.38 GPa, and its mechanical toughness was 7.19 MJ / m. 3 Obtained through DMA T g It is only 92.8 ℃.

[0052] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A process for the preparation of an amine-modified oligomeric crosslinked epoxy resin material, characterized in that, The preparation method comprises the following steps: (1) preparing triethylamine-terminated inorganic ion oligomer and ethanol colloid by liquid phase acid-base neutralization method; (2) dispersing the triethylamine-terminated inorganic ion oligomer and ethanol colloid obtained in step (1) in a liquid amine curing agent, and heating to prepare an amine-modified inorganic ion oligomer / amine curing agent solution; (3) mixing the amine-modified inorganic ion oligomer / amine curing agent solution obtained in step (2) with an epoxy resin, and cross-linking and curing to obtain an epoxy resin composite material.

2. The method for preparing the amine-modified oligomer crosslinked epoxy resin material according to claim 1, characterized in that, In step (1), the inorganic ion oligomer is at least one of calcium phosphate oligomer, calcium carbonate oligomer and calcium sulfate oligomer.

3. The method for preparing the amine-modified oligomer crosslinked epoxy resin material according to claim 1, characterized in that, In step (2), the liquid amine curing agent is at least one of polyetheramine, diethylene triamine, triethylene tetramine, ethylenediamine, 3-diethylaminopropylamine, m-xylene diamine and o-aminophenoxyethylamine.

4. The method for preparing the amine-modified oligomer crosslinked epoxy resin material according to claim 1, characterized in that, In step (2), the mass ratio of the liquid amine curing agent to the triethylamine-terminated inorganic ion oligomer and ethanol colloid is 3-15:

1.

5. The method for preparing the amine-modified oligomer crosslinked epoxy resin material according to claim 1, characterized in that, In step (2), the heating temperature is greater than or equal to 60 DEG C and lower than the boiling point of the liquid amine curing agent.

6. The method for preparing the amine-modified oligomer crosslinked epoxy resin material according to claim 1, characterized in that, In step (3), the proportion of the amine-modified inorganic ion oligomer in the epoxy resin composite material is 0.1-0.5wt%.

7. The method for preparing the amine-modified oligomer crosslinked epoxy resin material according to claim 1, characterized in that, In step (3), the curing temperature is 80-125 DEG C, and the curing time is 7-8 h.

8. The epoxy resin composite material prepared by the preparation method according to any one of claims 1-7.

9. The epoxy resin composite according to claim 8, characterized in that The mechanical strength of the epoxy resin composite is 128-140 MPa, the mechanical toughness is 7-10 MJ / m 3 , and the insulation breakdown strength is 100-120 kV / mm.

10. Application of the epoxy resin composite material according to claim 8 or 9 in the field of power system insulating pole towers, insulating cross arms, cable joint potting adhesives and electronic packaging.

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