Resin composition, electrical insulator prepared therefrom, and method for preparing electrical insulator

Abstract

The application discloses a resin composition, an electrical insulating part prepared from the resin composition and a preparation method of the electrical insulating part. The resin composition for the electrical insulating part of the application is composed of the following components in parts by weight: 70-90 parts of bisphenol A type epoxy resin, 10-30 parts of alicyclic epoxy resin, 45-65 parts of a curing agent, 300-500 parts of a heat-conducting filler and 5-30 parts of a toughening agent OX; the toughening agent OX is a bisphenol A type epoxy resin containing an oxazolidone structure. The special epoxy resin toughening agent containing an oxazolidone structure is added in the formula, the use of the alicyclic epoxy resin is reduced, and a formula with a higher Tg is obtained.

Description

Technical Field

[0001] This invention relates to the field of insulating materials, and more specifically to a resin composition for electrical insulation components, an electrical insulation component prepared therefrom, and a method for preparing the electrical insulation component. Background Technology

[0002] Epoxy resin formulations produce epoxy insulation components with excellent mechanical and electrical properties, making them widely used in power systems, rail transportation, and new energy fields. However, in practical applications, many situations require epoxy insulation materials with higher glass transition temperatures (Tg) due to excessive localized temperature rise. But epoxy insulation materials with high Tg have relatively poor toughness and are prone to cracking under certain application conditions.

[0003] There are many ways to toughen epoxy resin, such as rubber toughening, inorganic nanoparticle toughening, and core-shell structure particle toughening, but they all have corresponding problems: rubber toughening will significantly reduce the modulus of the material, thereby reducing the stiffness of the material and making the material easy to deform; inorganic nanoparticles and core-shell structure particles are difficult to disperse in resin, often requiring special equipment, making them relatively difficult to use and resulting in poor processability. Summary of the Invention

[0004] To address the issue that epoxy insulation materials cannot simultaneously possess high heat resistance (Tg) and high toughness, this invention uses bisphenol A epoxy resin and alicyclic epoxy resin as the matrix to provide insulation, high Tg, and fixation functions. However, the inventors discovered that the introduction of alicyclic epoxy resin increases the brittleness of the system, and while ordinary toughening agents provide toughening, they reduce the material's heat resistance. This invention adds a special epoxy resin toughening agent containing an oxazolidinone structure to the formulation, which can reduce the use of alicyclic epoxy resin and obtain a formulation with a higher Tg.

[0005] Based on this, in a first aspect, the present invention provides a resin composition for electrical insulation components, comprising the following components in parts by weight:

[0006]

[0007] The toughening agent OX is a bisphenol A type epoxy resin containing an oxazolidinone structure.

[0008] In a specific embodiment, the resin composition comprises the following components in parts by weight:

[0009]

[0010]

[0011] The general structure of a bisphenol A type epoxy resin matrix is ​​as follows:

[0012]

[0013] Where n represents the degree of aggregation.

[0014] Bisphenol A type epoxy resin products may also contain conventional excipients, the specific excipients of which vary depending on the product.

[0015] In a specific embodiment, the bisphenol A type epoxy resin has an epoxy value of 0.09-0.22 eq / 100g, and its main body can be selected from one or more combinations of E20, E12 or E14. The bisphenol A type epoxy resin is preferably Huntsman's CT5531CI, and the main body of this resin is E20.

[0016] In a specific embodiment, the alicyclic epoxy resin is selected from Huntsman's CY179, or one or more combinations of TTA182, TTA26, or TTA21 from Tetel, preferably CY179. This invention utilizes the high Tg of cured alicyclic epoxy resins to increase the Tg of bisphenol A type epoxy resins, thereby meeting the requirements for high-temperature resistance of the system.

[0017] In a specific embodiment, the toughening agent OX is formed by reacting bisphenol A type epoxy resin with diphenylmethane diisocyanate (MDI) under the catalysis of an imidazole catalyst to form a bisphenol A type epoxy resin containing an oxazolidinone structure.

[0018] Preferably, the method for preparing the toughening agent OX includes the following steps:

[0019] After dehydrating the bisphenol A epoxy resin by heating it at 100-140℃, the temperature was lowered to 70-90℃, and an imidazole catalyst was added. During the stirring process, diphenylmethane diisocyanate was added dropwise. After the addition was completed, the reaction was kept at the temperature for 3-5 hours to obtain the bisphenol A type epoxy resin containing the oxazolidinone structure.

[0020] In a specific embodiment, in the above-mentioned method for preparing OX, the bisphenol A type epoxy resin is selected from one or more combinations of E51, E54 or E44. Since the prepared OX has greater rigidity, it will not cause the Tg to decrease. E51 type is preferred.

[0021] In a specific embodiment, in the above-mentioned method for preparing OX, the imidazole catalyst is selected from one or more combinations of 2-methylimidazole, imidazole, 2-ethylimidazole, and 2-phenylimidazole, preferably 2-methylimidazole.

[0022] In a specific embodiment, in the above-mentioned method for preparing OX, the mass ratio of the bisphenol A type epoxy resin, diphenylmethane diisocyanate, and imidazole catalyst is 190-220:115-125:0.18-0.22; preferably 200:120:0.2.

[0023] In a specific implementation, the toughening agent OX has the following structure:

[0024]

[0025] In a specific embodiment, the curing agent is selected from one or more combinations of solid modified hexahydrophthalic anhydride, solid modified tetrahydrophthalic anhydride, or methylnadic anhydride, preferably solid modified hexahydrophthalic anhydride. The solid modified hexahydrophthalic anhydride, solid modified tetrahydrophthalic anhydride, or methylnadic anhydride can be commercially available products, such as the solid modified tetrahydrophthalic anhydride curing agent HT5535CI supplied by Huntsman Advanced Chemical Materials (Guangdong) Co., Ltd.

[0026] In a specific embodiment, the thermally conductive filler is selected from one or more of alumina, silica powder, wollastonite, and glass fiber, preferably alumina; it is mainly used to provide reinforcement and thermal conductivity.

[0027] A second aspect of the present invention provides a method for preparing an electrical insulating component using the above-described resin composition for electrical insulating components, comprising the following steps:

[0028] (1) After melting the epoxy resin and toughening agent OX at 110-130℃, add the thermally conductive filler and stir at this temperature for 2-4 hours to fully impregnate the epoxy resin and thermally conductive filler.

[0029] (2) Add the molten curing agent to the mixture obtained in step (1) and evacuate the vacuum at a degree of 0.3-0.5 MPa. Stir at a speed of 30-100 r / min and evacuate the vacuum for 10-20 min while stirring.

[0030] (3) The mixture obtained in step (2) is poured into a mold under vacuum, and after curing, it is demolded to obtain an electrical insulation component.

[0031] Electrical insulation components prepared using the resin composition for electrical insulation components according to the present invention possess both high Tg and high toughness. For example, the Tg can be above 130°C, preferably above 135°C, and below 150°C, particularly below 146.5°C, and the toughness can be 13 kJ / m. 2 The preferred value is 15 kJ / m. 2 The above, and 20kJ / m 2 Below, especially 19.5 kJ / m 2 the following.

[0032] In a third aspect, the present invention provides an electrical insulating component made of the epoxy resin composition of the first aspect or prepared by the method of the second aspect.

[0033] Beneficial effects:

[0034] The addition of a special bisphenol A type epoxy resin toughening agent containing an oxazolidinone structure to the formulation of this invention can reduce the use of aliphatic epoxy resin and obtain a formulation with a higher Tg. Compared with conventional toughening agents, such as DY040, OX is an epoxy resin containing an oxazolidinone structure. Compared with ordinary epoxy resins, the addition of this special structure to ordinary epoxy resin systems can reduce the crosslinking density, thereby improving the toughness of the epoxy resin formulation. On the other hand, the presence of the oxazolidinone structure in the molecular chain provides rigidity, thus reducing the crosslinking density without excessively lowering the Tg. Detailed Implementation

[0035] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] Reagents:

[0037] Bisphenol A type epoxy resin: model CT5531CI, purchased from Smex Advanced Chemical Materials (Guangdong) Co., Ltd.

[0038] Aliphatic epoxy resin: Model CY179, purchased from Smite Advanced Chemical Materials (Guangdong) Co., Ltd.

[0039] Solid modified hexahydrophthalic anhydride: model HT5535CI, purchased from Smex Advanced Chemical Materials (Guangdong) Co., Ltd.

[0040] Alumina: Model RF-2, purchased from Taian Shengyuan Powder Co., Ltd.

[0041] DY040: Purchased from Smite Advanced Chemical Materials (Guangdong) Co., Ltd.

[0042] OX: Synthesized using E51 epoxy resin (purchased from Kunshan Nanya Epoxy Resin Co., Ltd.) and modified liquid MDI (diphenylmethane diisocyanate, purchased from Shandong Wanhua Group Co., Ltd.) as the main materials. The specific synthesis process is as follows:

[0043] 200g of E51 epoxy resin was dehydrated by heating and vacuuming for 4 hours, then cooled to 70℃, and 0.2g of 2-methylimidazole catalyst was added. After mechanical stirring for 1 hour, approximately 120g of liquid MDI was added dropwise at a rate of 40mL / min. After the addition was complete, the reaction was maintained at this temperature for 4 hours to obtain the desired product OX.

[0044] Table 1 lists the epoxy resin material formulations for the embodiments and comparative examples of the present invention.

[0045] Table 1. Formulation of Epoxy Resin Compositions for Electrical Insulation Components (Unit: Parts by Weight)

[0046]

[0047] The high-Tg, high-toughness epoxy compositions for electrical insulation provided in Examples 1-4 and Comparative Examples 1-5 are used to prepare high-Tg, high-toughness electrical insulation components. Specific steps include:

[0048] (1) After the epoxy resin and toughening agent are melted at 110 resin, alumina filler is added and stirred at this temperature for 4 hours to fully impregnate the resin and filler.

[0049] (2) Add the molten curing agent to the mixture obtained in step (1) and evacuate the vacuum at a vacuum degree of 0.4 MPa and a stirring speed of 60 r / min for 10 min while stirring.

[0050] (3) The mixture obtained in step (2) is poured into a mold under vacuum, and after curing, it is demolded to obtain an electrical insulation component with high Tg and high toughness.

[0051] Using the material formulation provided in Comparative Example 1, conventional epoxy insulation components are prepared, including:

[0052] (1) After the epoxy resin is melted at 110 resin, alumina filler is added and stirred at this temperature for 4 hours to fully impregnate the resin and filler.

[0053] (2) Add the molten curing agent to the mixture obtained in step (1) and evacuate the vacuum at a vacuum degree of 0.4 MPa and a stirring speed of 60 r / min for 10 min while stirring.

[0054] (3) The mixture obtained in step (2) is poured into a mold under vacuum, and after curing, it is demolded to obtain a conventional epoxy insulation strip.

[0055] The insulating components prepared according to the formulations provided in Examples 1-4 and Comparative Examples 1-5 were subjected to performance tests. The test results are shown in Table 2. The performance evaluation methods and test standards are as follows:

[0056] Tg: ISO 11357-2:1999 Plastics—Differential scanning calorimetry (DSC)—Part 2: Determination of glass transition temperature.

[0057] Tensile strength: ISO 527-1:2012 Plastics - Determination of tensile properties - Part 1: General.

[0058] Flexural strength: ISO 178:2001 Plastics—Determination of flexural properties.

[0059] Impact strength: ISO 179-1:2000 Plastics—Determination of impact properties of simply supported beams—Part 1: Non-instrumental impact testing.

[0060] Breakdown field strength: IEC 60243-1:2013 Solid insulating materials - Test methods for electrical strength - Part 1: Tests at power frequency.

[0061] Volume resistivity: EC 62631-3-1:2016 Dielectric and resistive properties of solid insulating materials - Part 3-1: Determination of resistive properties (DC method) - Volume resistivity and volume resistivity - General methods.

[0062] Table 2. Performance Test Data Table

[0063]

[0064] The test results above show that the toughness of Comparative Example 1 is far inferior to that of Examples 1-4 and Comparative Examples 2-5, which have added toughening agents. DY040 (polyhydroxy polyether compound) is a conventional toughening agent that mainly improves the toughness of the cured product by reducing the crosslinking density of the system, but this often comes at the cost of sacrificing the heat resistance of the product. For example, in Comparative Examples 1-5, as the amount of DY040 added increased, the results showed that the Tg of the cured product decreased significantly.

[0065] In mixed epoxy resin systems, the high Tg of alicyclic epoxy resins is generally utilized to increase the Tg of bisphenol A type epoxy resins. However, the lower the amount of alicyclic epoxy resin used, the lower the Tg (this is determined by the structure of alicyclic epoxy). Furthermore, using alicyclic epoxy reduces toughness. Therefore, for general toughening systems, high toughness and high Tg are mutually exclusive. However, Examples 1-4, using OX as a toughening agent, achieved higher Tg than Comparative Examples 2-5 even with a significantly lower amount of alicyclic epoxy and a higher amount of toughening agent compared to the comparative examples. This demonstrates that a higher Tg is achieved with reduced alicyclic epoxy content, showcasing the high toughness and high Tg characteristics of the formulation. This may be because the addition of OX itself has little effect on reducing Tg, and may also promote the curing of the system, resulting in a more complete molecular chain structure in the cured product under the same curing process, thus leading to superior overall performance.

[0066] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A resin composition for electrical insulation components, characterized in that, It is composed of the following components in parts by weight: The main body of the first bisphenol A type epoxy resin is selected from one or more combinations of E20, E12 or E14; The alicyclic epoxy resin is selected from one or more combinations of CY179, TTA182, TTA26 or TTA21; The curing agent is selected from one or more combinations of solid modified hexahydrophthalic anhydride, solid modified tetrahydrophthalic anhydride, or methylnadic anhydride. The thermally conductive filler is selected from one or more of alumina, silica powder, wollastonite, and glass fiber; The toughening agent OX is a bisphenol A type epoxy resin containing an oxazolidinone structure, formed by reacting a second bisphenol A type epoxy resin with diphenylmethane diisocyanate under the catalysis of an imidazole catalyst. The second bisphenol A type epoxy resin is selected from one or more combinations of E51, E54 or E44; The imidazole catalyst is selected from one or more combinations of 2-methylimidazolium, imidazolium, 2-ethylimidazolium, and 2-phenylimidazolium; The mass ratio of the bisphenol A type epoxy resin, diphenylmethane diisocyanate, and imidazole catalyst is 190-220:115-125:0.18-0.

22.

2. The resin composition for electrical insulation components according to claim 1, characterized in that, It is composed of the following components in parts by weight:

3. The resin composition for electrical insulation components according to claim 1 or 2, characterized in that, The epoxy value of the bisphenol A type epoxy resin is 0.09-0.22 eq / 100g.

4. The resin composition for electrical insulation components according to claim 1 or 2, characterized in that, The first bisphenol A type epoxy resin is CT5531CI.

5. The resin composition for electrical insulation components according to claim 1 or 2, characterized in that, The alicyclic epoxy resin is CY179.

6. The resin composition for electrical insulation components according to claim 1 or 2, characterized in that, The preparation method of the toughening agent OX includes the following steps: After dehydrating the second bisphenol A type epoxy resin by heating at 100-140℃, the temperature was lowered to 70-90℃, and an imidazole catalyst was added. During the stirring process, diphenylmethane diisocyanate was added dropwise. After the addition was completed, the reaction was kept at the temperature for 3-5 hours to obtain the bisphenol A type epoxy resin containing the oxazolidinone structure.

7. The resin composition for electrical insulation components according to claim 1, characterized in that, In the preparation method of OX, the second bisphenol A type epoxy resin is E51 type; The imidazole catalyst is 2-methylimidazole; The mass ratio of the bisphenol A type epoxy resin, diphenylmethane diisocyanate, and imidazole catalyst is 200:120:0.

2.

8. The resin composition for electrical insulation components according to claim 1, characterized in that, The toughening agent OX has the following structure: 。 9. The resin composition for electrical insulation components according to claim 1 or 2, characterized in that, The curing agent is a solid modified hexahydrophthalic anhydride; and / or The thermally conductive filler is alumina.

10. A method for preparing an electrical insulating component using the resin composition for electrical insulating components according to any one of claims 1-9, comprising the following steps: (1) After melting the first bisphenol A type epoxy resin and the toughening agent OX at 110°C, add the thermally conductive filler and stir at this temperature for 2-4 hours to fully impregnate the first bisphenol A type epoxy resin and the thermally conductive filler. (2) Add the molten curing agent to the mixture obtained in step (1) and evacuate the vacuum to a degree of 0.3-0.5 MPa. Stir at a speed of 30-100 r / min for 10-20 min while stirring. (3) The mixture obtained in step (2) is poured into a mold under vacuum, and after curing, it is demolded to obtain an electrical insulation component.

11. An electrical insulating component made of the resin composition for electrical insulating components according to any one of claims 1-9, or prepared by the method according to claim 10.

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