Insulating epoxy resin composition suitable for VPG process and application thereof

Abstract

The invention discloses an epoxy resin composition and a preparation method thereof, and the epoxy resin composition is suitable for an APG process and can be used for preparing and molding a high-quality epoxy insulating part. The epoxy resin composition is composed of epoxy resin, a curing agent, aluminum oxide, wollastonite and a flexibilizer. According to the epoxy resin composition disclosed by the invention, the influence of aluminum oxide on the viscosity of the whole mixture is relatively small, and a large amount of aluminum oxide can be added, so that the shrinkage of an insulating part in a curing process can be reduced, the internal stress of a product is reduced, and finally, the cracking trend of the product is reduced. Meanwhile, a certain amount of wollastonite is added into the composition, and the anti-cracking performance of the formula can be further improved due to the fact that the wollastonite has a certain length-diameter ratio.

Description

Technical Field

[0001] The present invention relates to the field of insulating materials, and in particular to an epoxy resin composition suitable for VPG process molding of electrical insulating parts, and a method for preparing electrical insulating parts by using the composition through the VPG process. Background Art

[0002] Insulation components produced using composite materials containing epoxy resins exhibit excellent mechanical and electrical properties and are widely used in power systems, rail transit, and new energy applications. Currently, the APG or VC processes are primarily used to produce insulation components. The APG process is highly efficient, using liquid resin and liquid curing agent. However, due to its inability to create a vacuum, the resulting product exhibits a high degree of defects, often limiting its production to medium-voltage insulation components. The VC process maintains a vacuum during the casting process, resulting in fewer defects and high-quality insulation components, making it suitable for high-voltage applications. However, due to its use of solid resin and solid curing agent, the curing speed is slow and the molding efficiency is low. The VPG process combines the advantages of both processes: it allows for vacuuming before molding, further eliminating defects, and its use of liquid resin and liquid curing agent allows for rapid curing and higher molding efficiency. However, conventional epoxy resin systems used in APG are often unsuitable for the VPG process. Therefore, developing epoxy resin formulations suitable for VPG applications is crucial for electrical insulation components. Summary of the Invention

[0003] The purpose of the present invention is to develop an epoxy resin composition and a preparation method thereof, which are suitable for APG process and can be used to prepare high-quality epoxy insulation parts.

[0004] In order to achieve the above object, according to the first aspect of the present invention, an object of the present invention is to provide an epoxy resin composition, which is composed of the following components in parts by weight;

[0005]

[0006] Preferably, the epoxy resin composition according to the present invention is composed of the following components in parts by weight:

[0007]

[0008] Preferably, the epoxy resin composition according to the present invention is composed of the following components in parts by weight:

[0009]

[0010] Preferably, the epoxy resin includes bisphenol A epoxy resin, alicyclic epoxy resin, bisphenol F epoxy resin and the like.

[0011] Preferably, the curing agent is modified methyltetrahydrophthalic anhydride, or modified methylhexahydrophthalic anhydride, or a mixture of the two.

[0012] Preferably, the toughening agent is H20.

[0013] According to the second aspect of the present invention, another object of the present invention is to provide a method for preparing an electrical insulation component using the epoxy resin composition, comprising:

[0014] (1) Add the epoxy resin, curing agent, toughening agent, alumina and wollastonite measured according to the formula into a vacuum mixing tank in sequence, with a vacuum degree of 0.3-0.5 MPa and a stirring speed of 30-100 r / min, and evacuate the mixture while stirring for 2-3 hours;

[0015] (2) The mixture obtained in step (1) is injected into a VPG mold at a temperature of 140-150° C. under a pressure of 0.1-0.4 MPa, cured for 10-20 minutes, and demolded to obtain an electrical insulation component.

[0016] According to the third aspect of the present invention, another object of the present invention is to provide an electrical insulation part, which is made of the epoxy resin composition according to the first aspect of the present invention, or prepared by the method according to the second aspect of the present invention.

[0017] Beneficial effects

[0018] The beneficial effects of the present invention are:

[0019] (1) Since alumina has little effect on the viscosity of the entire mixture, it can be added in large quantities, thereby reducing the shrinkage of the insulating parts during the curing process, thereby reducing the internal stress of the product and ultimately reducing the tendency of the product to crack.

[0020] (2) Adding a certain amount of wollastonite to the formula system can further improve the anti-cracking performance of the formula because wollastonite has a certain aspect ratio. DETAILED DESCRIPTION

[0021] The present invention will be described in detail below. Before describing, it should be understood that the terms used in this specification and the appended claims should not be interpreted as limited to the general meaning and dictionary meaning, but should be interpreted according to the meaning and concept corresponding to the technical aspects of the present invention on the basis of the principle that allows the inventor to appropriately define the terms for the best interpretation. Therefore, the descriptions presented here are merely preferred examples for illustrative purposes and are not intended to limit the scope of the present invention. It should be understood that other equivalents or improvements can be obtained therefrom without departing from the spirit and scope of the present invention.

[0022] As used herein, the terms "comprises," "includes," "has," "contains" or any other similar terms are open conjunctions that are intended to cover non-exclusive inclusions. For example, a composition or article containing multiple elements is not limited to the elements listed herein, but may also include other elements that are not explicitly listed but are generally inherent to the composition or article. In addition, unless expressly stated to the contrary, the term "or" refers to an inclusive "or" rather than an exclusive "or." For example, any of the following situations satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist), A is false (or does not exist) and B is true (or exists), and both A and B are true (or exist). In addition, as used herein, the terms "comprises," "includes," "has," and "contains" should be interpreted as specifically disclosed and simultaneously cover closed or semi-closed conjunctions such as "consisting of" and "consisting essentially of."

[0023] Throughout this document, all features or conditions defined as numerical ranges or percentage ranges are for simplicity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered to encompass and specifically disclose all possible subranges and individual values ​​within those ranges, particularly integer values. For example, a description of a range "1 to 8" should be considered to specifically disclose all possible subranges such as 1 to 7, 2 to 8, 2 to 6, 3 to 6, 4 to 8, 3 to 8, and so forth, particularly those defined by all integer values, and should be considered to specifically disclose individual values ​​within those ranges such as 1, 2, 3, 4, 5, 6, 7, and 8. Unless otherwise indicated, the foregoing interpretation applies to all of the present disclosure, regardless of whether the ranges are comprehensive or not.

[0024] If a quantity or other value or parameter is expressed as a range, a preferred range, or a series of upper and lower limits, it should be understood that all ranges consisting of any upper limit or preferred value of the range and any lower limit or preferred value of the range have been specifically disclosed herein, regardless of whether these ranges are disclosed separately. In addition, when a numerical range is mentioned herein, unless otherwise specified, the range should include its endpoints and all integers and fractions within the range.

[0025] In this document, numerical values ​​should be understood to have the accuracy of the number of significant digits of the numerical value, provided that the purpose of the invention can be achieved. For example, the number 40.0 should be understood to cover the range from 39.50 to 40.49.

[0026] The epoxy resin composition of the present invention can provide the final molded insulating part with excellent insulation performance, reliable heat resistance and stable fixing function through a scientific and reasonable ratio of ingredients.

[0027] Among them, alumina, as a key functional filler, can not only significantly enhance the mechanical strength of the composition, improve the overall structural stability of the insulating parts, and resist external mechanical impact, but also has excellent thermal conductivity, which can efficiently conduct the heat generated during the operation of the insulating parts, avoiding local excessive temperatures that affect their performance and service life.

[0028] Wollastonite, a special filler, plays a crucial role in crack prevention in the formulation. Its unique needle-like structure allows it to be evenly dispersed within the epoxy resin matrix, effectively inhibiting the initiation and propagation of microcracks. When insulation components are subject to external factors such as temperature fluctuations and mechanical stress, wollastonite disperses stress and reduces cracking caused by internal stress concentration, significantly enhancing the structural integrity and reliability of insulation components under complex operating conditions.

[0029] The addition of toughening agent H20 is to specifically improve the toughness of the formula. Epoxy resin itself has a certain brittleness and is prone to breakage when subjected to impact or vibration. H20 can form good compatibility with the epoxy resin matrix, and through intermolecular interactions, improve the flexibility of the system, so that the insulating parts have better deformation ability when subjected to external forces, reduce the occurrence of brittle fracture, and thus further ensure the safety and durability of the insulating parts. The following examples are only listed as examples of the embodiments of the present invention and do not constitute any limitation to the present invention. Those skilled in the art will understand that modifications within the scope of the essence and concept of the present invention fall within the scope of protection of the present invention. Unless otherwise specified, the reagents and instruments used in the following examples are commercially available products.

[0030] Reagents:

[0031] Bisphenol A epoxy resin: purchased from Nan Ya Epoxy Resin (Kunshan) Co., Ltd., NPEL128

[0032] Liquid methyltetrahydrophthalic anhydride: purchased from Puyang Huicheng Electronic Materials Co., Ltd.

[0033] Alumina: purchased from Taian Shengyuan Powder Co., Ltd., model RF-2

[0034] Wollastonite: purchased from Jiangsu Lianrui New Materials Co., Ltd., model NZ1180

[0035] Toughening agent H20: purchased from Yixing Pulitai Electronic Materials Co., Ltd., model H20

[0036] Examples 1 and 2

[0037] According to the formulation of this embodiment listed in Table 1 below, epoxy insulation specimens were prepared according to the following method.

[0038] (1) Add bisphenol A epoxy resin, curing agent, toughening agent, alumina and wollastonite into a vacuum mixing tank in sequence, with a vacuum degree of 0.3-0.5 MPa and a stirring speed of 30-100 r / min, and evacuate the mixture while stirring for 2-3 hours;

[0039] (2) The mixture obtained in step (1) is injected into an APG mold at a temperature of 140-150° C. under a pressure of 0.1-0.4 MPa, cured for 10-20 minutes, and demolded to obtain epoxy resin insulation strips of epoxy insulation formula material for VPG.

[0040] Comparative Examples 1 and 2

[0041] According to the formulation of this embodiment listed in Table 1 below, epoxy insulation specimens were prepared according to the following method.

[0042] (1) Add bisphenol A epoxy resin, curing agent, toughening agent, silica powder and wollastonite into a vacuum mixing tank, with a vacuum degree of 0.3-0.5 MPa and a stirring speed of 30-100 r / min, and evacuate the mixture while stirring for 2-3 hours;

[0043] (2) The formulated material obtained in step (1) is injected into an APG mold at a temperature of 140-150° C. under a pressure of 0.1-0.4 MPa, cured for 10-20 minutes, and demolded to obtain a conventional epoxy resin insulation strip.

[0044] Table 1: Epoxy resin formulations for electrical insulation (unit: parts by weight (g))

[0045]

[0046]

[0047] Test Example 1

[0048] The epoxy resin insulation strips prepared according to Examples 1-2 and Comparative Examples 1-2 were tested. The test results are shown in Table 2. The performance evaluation method and test standards are as follows:

[0049] Viscosity: GB / T 10247-2008 Viscosity measurement method

[0050] Tensile strength: ISO 527-1:2012 Plastics - Determination of tensile properties - Part 1: General

[0051] Flexural strength: ISO 178:2001 Plastics - Determination of flexural properties

[0052] Impact strength: ISO 179-1:2000 Plastics - Determination of charpy impact properties - Part 1: Non-instrumented impact test

[0053] Breakdown field strength: IEC 60243-1:2013 Solid insulating materials - Electric strength test methods - Part 1: Tests at power frequency

[0054] Glass transition temperature: ISO 11357-2:1999 Plastics - Differential Scanning Calorimetry (DSC) - Part 2: Determination of glass transition temperature

[0055] Flame retardant properties: IEC 60695-11-10:2003 Fire hazard tests - Part 11-10: Test flame - 50W horizontal and vertical flame test

[0056] Glow Wire Test (GWFT): IEC 60695-2-12:2010 Fire hazard testing - Part 2-12: Glow wire - Basic test methods for hot wires - Glow wire flammability index (GWFI) test method for materials

[0057] Tracking resistance test: IEC 60587:2007 Test method for evaluating the resistance of electrical insulating materials to tracking and corrosion under severe environmental conditions

[0058] Table 2 Performance test data

[0059]

[0060]

[0061] The above test results show that when using the embodiment system of the present invention to produce products, the final product does not crack. Although the comparative examples used a partial silicon powder system and a full alumina system, the products still cracked. This may be because compared with silicon powder, adding alumina to the resin system can more easily form a dense structure, reducing the internal stress generated by curing shrinkage in the product. At the same time, adding a certain amount of wollastonite bridges between the alumina and promotes stress conduction, making the product more difficult to crack.

[0062] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. An epoxy resin composition, comprising the following components in parts by weight:

2. The epoxy resin composition according to claim 1, wherein The epoxy resin composition is composed of the following components in parts by weight:

3. The epoxy resin composition according to claim 1, wherein The epoxy resin composition is composed of the following components in parts by weight:

4. The epoxy resin composition according to any one of claims 1 to 3, characterized in that The epoxy resin includes bisphenol A epoxy resin, alicyclic epoxy resin and bisphenol F epoxy resin.

5. The epoxy resin composition according to any one of claims 1 to 3, characterized in that The curing agent is modified methyltetrahydrophthalic anhydride, modified methylhexahydrophthalic anhydride or a mixture of the two.

6. The epoxy resin composition according to any one of claims 1 to 3, characterized in that The toughening agent is H20.

7. A method for preparing an electrical insulating component using the epoxy resin composition according to any one of claims 1 to 3, comprising: (1) Add the epoxy resin, curing agent, toughening agent, alumina and wollastonite measured according to the formula into a vacuum mixing tank in sequence, with a vacuum degree of 0.3-0.5 MPa and a stirring speed of 30-100 r / min, and evacuate the mixture while stirring for 2-3 hours; (2) The mixture obtained in step (1) is injected into a VPG mold at a temperature of 140-150° C. under a pressure of 0.1-0.4 MPa, cured for 10-20 minutes, and demolded to obtain an electrical insulation component.

8. An electrical insulation part, made from the epoxy resin composition according to any one of claims 1 to 3, or prepared by the method according to claim 7.

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