Degradable epoxy resin composite insulating material as well as preparation method and application thereof

Abstract

The invention discloses a degradable epoxy resin composite insulating material as well as a preparation method and application thereof. By taking polylactide polyol and polycaprolactone polyol as a starting point, a series of insulated epoxy resin cured materials with excellent thermodynamic properties and electrical insulation properties are obtained by utilizing the open-loop chain transfer reaction of the polyol and epoxy resin under the action of a cationic initiator. The preparation method is simple, easy to understand in operation, controllable in reaction condition, easy to implement and suitable for large-scale industrial production, and compared with other insulating epoxy resin systems containing dynamic bonds, the raw materials of polylactide polyol and polycaprolactone polyol have the advantages of being low in price, rich in source, simple in synthesis process and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of thermosetting resin materials, and in particular to a degradable epoxy resin composite insulating material, a preparation method thereof, and applications thereof. Background Art

[0002] Epoxy resin is one of the most important thermosetting resins. Due to its excellent processing, bonding, electrical insulation, chemical stability, and physical and mechanical properties, it has been widely used in the automotive, aerospace, electrical and electronics, and construction industries. As the requirements for insulation material performance in power systems and electrical equipment continue to increase, conventional epoxy resin cured products can no longer meet the high voltage and high power requirements. The development of epoxy resin insulation composite materials with high insulation performance is essential. Improving electrical insulation performance can reduce the occurrence of faults such as leakage and short circuits, enhance the safety and reliability of electrical equipment, extend the service life of equipment, reduce maintenance costs, and meet the societal needs of energy conservation, emission reduction, and recycling. In recent years, research on the electrical insulation properties of epoxy resins has become an important research direction, attracting widespread attention from academia and industry.

[0003] In recent years, dynamic covalent chemistry has been discovered to enhance the electrical insulation properties of epoxy resins. Inspired by this discovery, researchers both domestically and internationally have introduced dynamic covalent bonds into the cross-linked epoxy resin network, producing a series of novel materials with excellent electrical insulation properties. However, utilizing dynamic bonds to enhance the insulation properties of epoxy resins often requires large amounts of solvent and requires only specific temperatures, severely hindering the widespread industrial application of electrical insulation resins.

[0004] CN114395216A discloses a bio-based hyperbranched polymer epoxy resin. This resin is prepared by dynamically crosslinking a ferulic acid hyperbranched epoxy resin and a citric acid hyperbranched polyester. The epoxy resin is formed by dynamically crosslinking the ferulic acid hyperbranched epoxy resin and the citric acid hyperbranched polyester. A large number of interfacial covalent bonds are formed in the crosslinked network structure, making the epoxy resin recyclable. Under the action of aqueous sodium hydroxide solution, it can be controllably degraded into ferulic acid and citric acid hyperbranched polyester. The degradation products, ferulic acid and citric acid hyperbranched polyester, can be used to prepare a fully bio-based epoxy resin, achieving green closed-loop recycling of the epoxy resin. The prepared resin has excellent mechanical properties, heat resistance, solvent resistance, hydrolysis resistance, creep resistance, and corrosion resistance. It can replace petroleum-based epoxy resins and is used in fields such as electronic packaging, insulation materials, and printed circuit boards.

[0005] CN117946370A discloses a method for preparing an ester bond curing agent, a degradable epoxy resin, and a composite material thereof. The method comprises uniformly mixing an acrylate monomer with an amine and reacting them at a specific temperature for a period of time to obtain an ester bond curing agent. The ester bond curing agent and epoxy monomer are then mixed and degassed in a vacuum drying oven to obtain an epoxy resin matrix, which is then poured into a tetrafluoroethylene mold and cured to obtain the degradable epoxy resin. The epoxy resin is then composited with carbon fiber and cured to obtain the composite material. The degradable epoxy resin or composite material is then added to a specific proportion of an acid, base, and solvent, placed in a reactor, and heated at 50-150°C for complete degradation. This invention utilizes an aza-Michael addition reaction between an acrylate and an amine to form a dynamic C-N bond, achieving a dual synergistic effect between the dynamic C-N bond and the ester bond, imparting enhanced dynamic properties to the material. This allows for gentle and rapid degradation while maintaining optimal material performance.

[0006] However, the preparation methods of modified epoxy resins in the existing technology are complex, the process is tedious and time-consuming. How to achieve a balance between mechanical properties, electrical insulation properties and degradability is of great significance to the widespread application and promotion of electrical insulation resins in the industrial field. Summary of the Invention

[0007] In view of the above problems, the present invention provides an epoxy resin with a simple preparation process. After curing, the resin has excellent electrical insulation and mechanical properties, and also has the characteristics of rapid degradation under alkaline conditions and biodegradation in the natural environment.

[0008] To achieve the above object, the technical solution adopted by the present invention is:

[0009] A degradable epoxy resin composite insulating material comprising polyester polyol, ester bond-containing epoxy resin, and a cationic initiator;

[0010] The polyester polyol is polylactide polyol and / or polycaprolactone polyol;

[0011] The structure of the polylactide polyol is as follows:

[0012]

[0013] The polycaprolactone polyol structure is as follows:

[0014]

[0015] wherein R is a C2-C6 alkyl group, p is a natural number of 2-4, m is a natural number of 2-8, and n is a natural number of 2-8;

[0016] The structural formula of the ester bond-containing epoxy resin is one of the following:

[0017]

[0018] Wherein, X and Y are independently any one of a C1-C12 aliphatic chain or aliphatic ring structure;

[0019] The mass ratio of the polyester polyol to the ester bond-containing epoxy resin is (20-40):(60-80).

[0020] The reaction mechanism of this invention is that the oxygen atom of the hydroxyl group combines with a carbon atom of the epoxy group to form a new carbon-oxygen bond. Simultaneously, the bond between the oxygen atom of the epoxy group and the other carbon atom breaks, forming a hydroxyl group. As the epoxy group ring opens, the hydroxyl group in the polyester polyol reacts with the epoxy group in the epoxy resin to form new chemical bonds, ultimately forming a three-dimensional network structure.

[0021] The molecular weight of the polyester polyol is 1000 to 6000 g / mol.

[0022] The cationic initiator comprises at least one of diazonium salt, diaryliodonium salt, triarylsulfonium salt, alkylsulfonium salt, iron arene salt, sulfonyloxy ketone and triarylsiloxane; and the amount used is 0.5%-5% of the total amount of the ester bond-containing epoxy resin.

[0023] The epoxy resin composite insulating material further comprises one or more of an epoxy diluent and an inorganic filler.

[0024] The epoxy diluent includes any one or a combination of two or more of butyl glycidyl ether, phenyl glycidyl ether, benzyl glycidyl ether, C12-14 fatty glycidyl ether, 1,4-butanediol diglycidyl ether, ethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, and neopentyl glycol diglycidyl ether;

[0025] The inorganic filler includes any one or a combination of two or more of talc, silicon dioxide, barium sulfate, aluminum oxide, boron nitride, and wollastonite.

[0026] The amount of the epoxy diluent is 5%-15% of the total amount of the ester bond epoxy resin;

[0027] The amount of the inorganic filler is 50%-300% of the total amount of the polyester polyol and the ester bond-containing epoxy resin.

[0028] The epoxy resin composite insulation material has a glass transition temperature of 60 to 130° C., a tensile strength of 60 to 80 MPa, a thermal conductivity coefficient of ≥0.5, and an electrical strength of ≥35 KV / cm.

[0029] The epoxy resin composite insulating material has a degradation rate of ≥99% within 2 to 168 hours in an alkaline aqueous solution at 25 to 100° C.

[0030] The present invention also provides a method for preparing the degradable epoxy resin composite insulating material, comprising the steps of: mixing raw materials including polyester polyol, ester bond-containing epoxy resin, and cationic initiator, and irradiating the mixture under 365nm ultraviolet light for 10 to 20 minutes or curing the mixture at 70 to 100°C for 2 to 12 hours to obtain the degradable epoxy resin composite insulating material.

[0031] The present invention also provides application of the degradable epoxy resin composite insulating material in electric power equipment.

[0032] This invention cleverly utilizes the unique degradation properties of polyol structures to develop a series of multifunctional biodegradable epoxy resins, successfully researching a series of novel electrically insulating epoxy resin compositions. The resulting cured resins maintain excellent thermodynamic and electrical insulation properties while also exhibiting rapid degradation under alkaline conditions and biodegradability in natural environments.

[0033] This innovative achievement has broad application prospects in the field of composite materials, indicating that the practical application of electrical insulating epoxy resins will enter a new stage of development, and is expected to truly promote this field towards a more environmentally friendly and sustainable direction.

[0034] The degradable epoxy resin composite insulating material composition provided by the present invention has a corresponding cured product that maintains excellent thermodynamic and electrical properties while also having good degradation properties, and is suitable for supporting, insulating and sealing power equipment.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] (1) The present invention takes polylactide polyol and polycaprolactone polyol as starting points, and utilizes the ring-opening chain transfer reaction between polyol and epoxy resin in the presence of a cationic initiator to obtain a series of insulating epoxy resin cured products; the preparation method is simple, the operation is easy to understand, the reaction conditions are controllable, and it is easy to implement, and is suitable for large-scale industrial production; at the same time, the cured resin material has both excellent thermodynamic properties and electrical insulation properties, and also has the characteristics of rapid degradation under alkaline conditions and biodegradation in the natural environment, and is suitable for high-end application fields that require high strength and electrical insulation of polymer materials.

[0037] (2) Compared with other insulating epoxy resin systems containing dynamic bonds, polylactide polyols and polycaprolactone polyols have the advantages of low price, abundant sources and simple synthesis process. More importantly, the insulating properties of polylactide and polycaprolactone-based polymers are better than those of existing polymers. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 is the NMR spectrum of the resin mixture in Example 1.

[0039] Figure 2 It is the NMR spectrum of the resin mixture in Example 3. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with embodiment. 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. Those skilled in the art will make modifications or equivalent substitutions based on understanding the technical solution of the present invention, without departing from the spirit and scope of the technical solution of the present invention, and all should be encompassed within the protection scope of the present invention.

[0041] The raw materials used in the following specific embodiments were purchased from the market, among which polylactide polyol was (diol, triol), polycaprolactone polyol was (diol, triol), and ester-bonded epoxy resin was purchased from Myrel Chemical Reagents.

[0042] Example 1

[0043] First, polycaprolactone diol (molecular weight 1000), epoxy resin 1, butyl glycidyl ether and diazonium salt photoinitiator were mixed uniformly at room temperature in a mass ratio of 20:80:5:0.5 to obtain a resin composition, and then mixed uniformly with talc powder in a mass ratio of 1:1. Finally, the resin composition system was irradiated under 365nm ultraviolet light for 20 minutes to obtain an epoxy resin composite insulating material.

[0044] The structures of polycaprolactone diol and epoxy resin 1 are as follows:

[0045]

[0046] The nuclear spectrum of the resin composition obtained from polycaprolactone diol and epoxy resin is as follows Figure 1 Performance test results show that the polycaprolactone epoxy resin composite insulation material has a glass transition temperature of 85°C, a tensile strength of 75 MPa, a relative dielectric constant of 4.5, a thermal conductivity of 0.65 (25°C), and an electrical strength of 35.81 kV / cm. In a 1 mol / L sodium hydroxide aqueous solution at 25°C, the degradation rate within 144 hours is 99%.

[0047] Example 2

[0048] First, polylactide diol (molecular weight 2000), epoxy resin 1, phenyl glycidyl ether and diaryliodonium salt photoinitiator were mixed uniformly at room temperature in a mass ratio of 25:75:6:0.6 to obtain a resin composition, and then mixed uniformly with silica in a mass ratio of 1:1.5. Finally, the resin composition system was irradiated under 365nm ultraviolet light for 15 minutes to obtain an epoxy resin composite insulating material.

[0049]

[0050]

[0051] The performance test results show that the composite insulation material made of polylactide diol (molecular weight 2000) has a glass transition temperature of 87°C, a tensile strength of 73 MPa, a relative dielectric constant of 4.5, a thermal conductivity of 0.64 (25°C), an electrical strength of 35.62 KV / cm, and a degradation rate of 99% within 96 hours in a 1 mol / L sodium hydroxide aqueous solution at 40°C.

[0052] Example 3

[0053] Polycaprolactone triol (molecular weight 3000), epoxy resin 1, benzyl glycidyl ether and triarylsulfonium salt photoinitiator were mixed uniformly at room temperature in a mass ratio of 30:70:8:2 to obtain a resin composition. Then, the mixture was mixed uniformly with barium sulfate in a mass ratio of 1:2. Finally, the resin composition system was cured at 80°C for 6 hours to obtain an epoxy resin composite insulating material.

[0054] The structures of polycaprolactone triol and epoxy resin 1 are as follows:

[0055]

[0056] The NMR spectrum of the resin composition prepared from polycaprolactone triol and epoxy resin is as follows: Figure 2 Performance test results show that the polycaprolactone epoxy resin composite insulation material has a glass transition temperature of 86°C, a tensile strength of 69 MPa, a relative dielectric constant of 4.5, a thermal conductivity of 0.63 (25°C), and an electrical strength of 35.73 kV / cm. In a 1 mol / L sodium hydroxide aqueous solution at 60°C, the degradation rate within 96 hours is 99%.

[0057] Example 4

[0058] Polycaprolactone diol (molecular weight 4000), epoxy resin 2, benzyl glycidyl ether and alkyl sulfonium salt photoinitiator were mixed uniformly at room temperature in a mass ratio of 35:65:9:2.5 to obtain a resin composition, and then mixed uniformly with aluminum oxide in a mass ratio of 1:1.5. Finally, the resin composition system was cured at 90°C for 7 hours to obtain an epoxy resin composite insulating material.

[0059] The structures of polycaprolactone diol and epoxy resin 2 are as follows:

[0060]

[0061] The performance test results show that the glass transition temperature of polycaprolactone epoxy resin composite insulation material is 85°C, the tensile strength is 68MPa, the relative dielectric constant is 4.49, the thermal conductivity is 0.65 (25°C), the electrical strength is 35.53KV / cm, and the degradation rate within 48 hours in 1mol / L sodium hydroxide aqueous solution at 80°C is 99%.

[0062] Example 5

[0063] Polycaprolactone triol (molecular weight 3000), epoxy resin 2, 1,4-butanediol diglycidyl ether and sulfonyloxy ketone photoinitiator are mixed uniformly at room temperature in a mass ratio of 40:60:10:3 to obtain a resin composition, and then mixed uniformly with boron nitride in a mass ratio of 1:2. Finally, the resin composition system is cured at 100°C for 10 hours to obtain an epoxy resin composite insulating material.

[0064] The structures of polycaprolactone triol and epoxy resin 2 are as follows:

[0065]

[0066] The performance test results show that the glass transition temperature of the polycaprolactone epoxy resin composite insulation material is 86°C, the tensile strength is 75MPa, the relative dielectric constant is 4.48, the thermal conductivity is 0.63 (25°C), the electrical strength is 35.41KV / cm, and the degradation rate within 72 hours in a 1mol / L sodium hydroxide aqueous solution at 100°C is 99%.

[0067] Example 6

[0068] Using the polycaprolactone diol (molecular weight 1000) of Example 1, the polycaprolactone diol, epoxy resin 2, ethylene glycol diglycidyl ether and iron aromatic salt photoinitiator were mixed uniformly at room temperature in a mass ratio of 20:80:12:4 to obtain a resin composition, and then mixed uniformly with wollastonite in a mass ratio of 1:1. Finally, the resin composition system was irradiated under 365nm ultraviolet light for 20 minutes to obtain an epoxy resin composite insulating material.

[0069] The structure of epoxy resin 3 is as follows:

[0070]

[0071]

[0072] The performance test results show that the glass transition temperature of polycaprolactone epoxy resin composite insulation material is 88°C, the tensile strength is 73MPa, the relative dielectric constant is 4.49, the thermal conductivity is 0.68 (25°C), the electrical strength is 35.89KV / cm, and the degradation rate within 120h in 1mol / L sodium hydroxide aqueous solution at 25°C is 99%.

[0073] Example 7

[0074] Using the polycaprolactone triol (molecular weight 3000) of Example 3, the polycaprolactone triol, epoxy resin 3, neopentyl glycol diglycidyl ether and triarylsiloxy ether photoinitiator were mixed uniformly at room temperature in a mass ratio of 30:70:15:5 to obtain a resin composition, and then mixed uniformly with barium sulfate in a mass ratio of 1:3. Finally, the resin composition system was cured at 100°C for 12 hours to obtain an epoxy resin composite insulating material.

[0075] The performance test results show that the glass transition temperature of the polycaprolactone epoxy resin composite insulation material is 89°C, the tensile strength is 78Mpa, the relative dielectric constant is 4.48, the thermal conductivity coefficient is 0.61 (25°C), the electrical strength is 36.01KV / cm, and the degradation rate within 144h in a 1mol / L sodium hydroxide aqueous solution at 100°C is 99%.

[0076] Table 1 Properties of epoxy resin composite insulation materials prepared from polyester polyols in Examples 1-7

[0077]

[0078] Table 2 Performance data of epoxy resin composite insulation materials prepared from polyester polyols in Examples 1-7

[0079]

[0080] The performance test results of the epoxy resin composite insulation materials of Examples 1-7 are summarized in Table 1 and Table 2. It can be seen that the composite materials have excellent electrical insulation and mechanical strength and are suitable for supporting, insulating and sealing power equipment.

Claims

1. A degradable epoxy resin composite insulating material, characterized in that: Including polyester polyol, epoxy resin containing ester bond, cationic initiator; The polyester polyol is polylactide polyol and / or polycaprolactone polyol; The structure of the polylactide polyol is as follows: The polycaprolactone polyol structure is as follows: wherein R is a C2-C6 alkyl group, p is a natural number of 2-4, m is a natural number of 2-8, and n is a natural number of 2-8; The structural formula of the ester bond-containing epoxy resin is one of the following: Wherein, X and Y are independently any one of a C1-C12 aliphatic chain or aliphatic ring structure; The mass ratio of the polyester polyol to the ester bond-containing epoxy resin is (20-40):(60-80).

2. The degradable epoxy resin composite insulating material according to claim 1, characterized in that: The molecular weight of the polyester polyol is 1000 to 6000 g / mol.

3. The degradable epoxy resin composite insulating material according to claim 1, characterized in that: The cationic initiator comprises at least one of diazonium salt, diaryliodonium salt, triarylsulfonium salt, alkylsulfonium salt, iron arene salt, sulfonyloxy ketone and triarylsiloxane; and the amount used is 0.5%-5% of the total amount of the ester bond-containing epoxy resin.

4. The degradable epoxy resin composite insulating material according to claim 1, characterized in that: The epoxy resin composite insulating material further comprises one or more of an epoxy diluent and an inorganic filler.

5. The degradable epoxy resin composite insulating material according to claim 4, characterized in that: The epoxy diluent includes any one or a combination of two or more of butyl glycidyl ether, phenyl glycidyl ether, benzyl glycidyl ether, C12-14 fatty glycidyl ether, 1,4-butanediol diglycidyl ether, ethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, and neopentyl glycol diglycidyl ether; And / or, the inorganic filler includes any one or a combination of two or more of talc, silicon dioxide, barium sulfate, aluminum oxide, boron nitride, and wollastonite.

6. The degradable epoxy resin composite insulation material according to claim 1, characterized in that: The amount of the epoxy diluent is 5%-15% of the total amount of the ester bond epoxy resin; And / or, the amount of the inorganic filler is 50%-300% of the total amount of the polyester polyol and the ester bond-containing epoxy resin.

7. The degradable epoxy resin composite insulation material according to claim 1, characterized in that: The epoxy resin composite insulation material has a glass transition temperature of 60 to 130° C., a tensile strength of 60 to 80 MPa, a thermal conductivity coefficient of ≥0.5, and an electrical strength of ≥35 KV / cm.

8. The degradable epoxy resin composite insulation material according to claim 1, characterized in that: The epoxy resin composite insulating material has a degradation rate of ≥99% within 2 to 168 hours in an alkaline aqueous solution at 25 to 100° C.

9. The method for preparing a degradable epoxy resin composite insulating material according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: mixing raw materials including polyester polyol, epoxy resin containing ester bond and cationic initiator, irradiating the mixture under 365nm ultraviolet light for 10 to 20 minutes or curing the mixture at 70 to 100°C for 2 to 12 hours.

10. Use of the degradable epoxy resin composite insulation material according to any one of claims 1 to 8 in power equipment.

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