Dry-type reactor encapsulation insulation epoxy resin system and preparation method thereof

Abstract

The invention discloses a dry-type reactor encapsulation insulation epoxy resin system and a preparation method thereof. The dry-type reactor encapsulation insulation epoxy resin system comprises the following components in parts by weight: 40-90 parts of electronic-grade epoxy resin, 20-90 parts of bisphenol F epoxy resin, 5-20 parts of oxazolidinone epoxy resin and 2-5 parts of a curing agent. The dry type reactor encapsulation insulation epoxy resin system provided by the invention can improve the humidity and heat resistance and toughness of the current epoxy resin insulation material, reduce the microcrack and water absorption of the epoxy resin insulation material, improve the insulation capability of the insulation material, and improve the impact resistance, short circuit resistance and insulation performance of the reactor.

Description

Technical Field

[0001] The invention relates to the field of insulating material formulation and process, and in particular to an epoxy resin system for encapsulating insulating dry-type reactors and a preparation method thereof. Background Art

[0002] Dry-type air-core reactors have been widely used in power systems due to their advantages of light weight, simple installation, low maintenance and low cost. However, years of operating experience have shown that local overheating and even fire accidents of dry-type air-core reactors occur from time to time.

[0003] At present, dry-type air-core reactors use long glass fiber bundles impregnated with epoxy resin to encapsulate the coils. Each package contains multiple aluminum wires of different specifications with inter-strand (inter-turn) insulation (polyimide film coated aluminum stranded wire) tightly wound in parallel. The aluminum stranded wires coated with polyimide film are fixed with epoxy resin. The coil packages are supported by epoxy pull-out rods to form air ducts. The upper and lower ends of the coils are positioned using a star frame welded with aluminum bars. The star frame terminal board plays a conductive role and serves as the incoming and outgoing busbars.

[0004] The main reasons for the damage of dry-type air-core reactors are excessive local temperature rise and inter-turn insulation breakdown. Analysis shows that if the inter-turn epoxy resin insulation material is in a high temperature and discharge environment for a long time, it will cause the insulation material to become brittle and deteriorate, produce microcracks, and gradually lose its original mechanical properties and insulation properties. If it is combined with hot and humid conditions, moisture will enter the reactor turns, and hot and humid aging can cause the inter-turn insulation performance of the dry-type air-core reactor to drop rapidly, which may cause local heating or even inter-turn short-circuit failure. Therefore, the heat resistance and toughness of epoxy resin insulation materials are crucial to the safe operation of dry-type reactors.

[0005] There are two types of epoxy resin systems. The first type consists of epoxy resin, curing agent, and accelerator, and the second type consists of epoxy resin and curing agent. The first type of formula consists of epoxy resin, acid anhydride curing agent such as methyltetrahydrophthalic anhydride, tetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, etc., and accelerators such as imidazoles, tertiary amines, and quaternary ammonium salt accelerators. The second type consists of epoxy resin and catalytic curing agent such as 2-ethyl-4-methylimidazole.

[0006] The first system has high brittleness, low insulation grade and poor weather resistance. The second system has excellent mechanical properties, dielectric properties and thermal stability, with a heat deformation temperature of 160°C and an insulation grade of H.

[0007] The above system has defects, such as poor wet and hot performance, low toughness, and low elongation at break. Microcracks are easily generated during the operation of the reactor. In a wet and hot environment, due to the capillary effect of the microcracks, moisture can easily be adsorbed into the microcracks. At the same time, due to the multiple effects of heat, electricity, oxygen, and cold and hot cycles, the surface of the epoxy resin is oxidized, the surface activity is increased, and the ability to adsorb moisture is also aggravated. Therefore, under the combined effects of moisture and heat, the insulation capacity of the epoxy resin decreases rapidly, causing the reactor to malfunction. In this case, neither the thermal deformation temperature nor the insulation grade of the epoxy resin will play a key role. How to reduce or even eliminate the microcracks and moisture and heat resistance of the insulating material are two key factors of the insulating material of the reactor. Summary of the invention

[0008] The invention provides a dry-type reactor encapsulation insulating epoxy resin system and a preparation method thereof, which can improve the moisture and heat resistance and toughness of the epoxy resin insulating material.

[0009] An embodiment of the present invention provides an epoxy resin system for encapsulating an insulating dry-type reactor, comprising the following components: 40 to 90 parts by weight of electronic-grade epoxy resin, 20 to 90 parts by weight of bisphenol F epoxy resin, 5 to 20 parts by weight of oxazolidinone epoxy resin, and 2 to 5 parts by weight of a curing agent.

[0010] Furthermore, the dry-type reactor encapsulation insulating epoxy resin system also includes the following components: 0-5 parts by weight of hyperbranched polymer and 0-5 parts by weight of nano core-shell polymer, wherein the weight of hyperbranched polymer and nano core-shell polymer are not 0.

[0011] Furthermore, the dry-type reactor encapsulation insulating epoxy resin system further comprises the following components: 0 to 2 parts by weight of a rheological additive, wherein the weight of the rheological additive is not 0.

[0012] Further, the hyperbranched polymer includes polyether polyols.

[0013] Further, the rheology modifier includes sheet silicate.

[0014] Further, the curing agent includes 2-ethyl-4-methylimidazole.

[0015] An embodiment of the present invention also provides a method for preparing an insulating epoxy resin system for encapsulating a dry-type inductor, comprising the following steps: in a vacuum environment, stirring an electronic-grade epoxy resin and a bisphenol F epoxy resin at 40 to 100° C. for 10 to 20 minutes, then adding an oxazolidinone epoxy resin and stirring for 30 to 60 minutes, then cooling to 40 to 50° C., adding a curing agent, stirring for 5 to 15 minutes, and discharging the material to obtain the insulating epoxy resin system for encapsulating a dry-type inductor.

[0016] Furthermore, when the oxazolidinone epoxy resin is added, a hyperbranched polymer and a nano core-shell polymer are also added.

[0017] Furthermore, when the oxazolidinone epoxy resin is added, a rheological additive is also added.

[0018] Furthermore, before using the electronic grade epoxy resin, the electronic grade epoxy resin is heated to above 40°C.

[0019] Furthermore, before using the curing agent, the curing agent is heated to above 35°C.

[0020] The present invention has the following beneficial effects:

[0021] The present invention reduces polar groups in the molecular structure of the epoxy resin matrix by adding oxazolidone epoxy resin, thereby reducing the interaction between the resin matrix and water, thereby reducing the water absorption rate of the resin matrix.

[0022] The present invention improves the wet and thermal properties of the material by introducing heat-resistant group oxazolidone epoxy resin and other low water absorption, high temperature resistance, and toughness materials into the resin system.

[0023] The present invention can improve the weather resistance of the epoxy resin system and reduce the viscosity of the system by adding an epoxy resin with good weather resistance, such as bisphenol F epoxy resin, into the system.

[0024] The invention reduces the internal stress of the epoxy resin system during the curing and application process and increases the toughness of the material by adding a hyperbranched polymer into the system. Compared with conventional toughening materials, the polyether polyol hyperbranched polymer is added in a smaller amount and has significantly improved performance, thus avoiding the problems of increased viscosity, large addition amount and reduced heat resistance of the material caused by conventional toughening materials.

[0025] The present invention can improve the anti-crack ability of the material and the anti-sagging performance of the resin by adding a rheological additive-sheet silicate into the system as needed, thereby preventing excessive loss of resin during operation, resulting in defects such as glue shortage and bubbles.

[0026] The present invention reduces the volatile matter and bubbles in the epoxy resin system by optimizing the mixing process of the epoxy resin, thereby ensuring the mixing uniformity of the system materials.

[0027] In general, the dry-type reactor encapsulated insulating epoxy resin system of the present invention can improve the moisture and heat resistance and toughness of current epoxy resin insulating materials, reduce microcracks and water absorption of epoxy resin insulating materials, improve the insulating capacity of insulating materials, and improve the impact resistance, short-circuit resistance and insulation performance of the reactor. The dry-type reactor encapsulated insulating epoxy resin system of the present invention can overcome the problems of large brittleness, easy cracking and water absorption, and poor weather resistance of the encapsulated insulating layer of the existing reactor during outdoor operation. The dry-type reactor encapsulated insulating epoxy resin system of the present invention can ensure that the coil has excellent sealing integrity, resistance to thermal expansion and contraction, insulation, weather resistance, and crack resistance, thereby ensuring excellent electrical machinery and electrical performance and reducing the risk of power grid accidents. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0029] An embodiment of the present invention provides an epoxy resin system for encapsulating an insulating dry-type reactor, comprising the following components: 40 to 90 parts by weight of electronic-grade epoxy resin, 20 to 90 parts by weight of bisphenol F epoxy resin, 5 to 20 parts by weight of oxazolidinone epoxy resin, 0 to 5 parts by weight of hyperbranched polymer, 0 to 5 parts by weight of nano core-shell polymer, 0 to 2 parts by weight of rheological additive, and 2 to 5 parts by weight of curing agent.

[0030] Electronic grade epoxy resin is used as the main resin of the dry reactor encapsulation insulation epoxy resin system. The electronic grade epoxy resin can be electronic grade epoxy resin 828. For the above electronic grade epoxy resin, domestic resin manufacturers include Wuxi Phoenix and Yueyang Petrochemical, and foreign resin manufacturers include Dow and HUNTSMAN. The amount of electronic grade epoxy resin can be 40, 60, 80, 90 parts by weight.

[0031] Bisphenol F epoxy resin is used to improve weather resistance and reduce viscosity. The bisphenol F epoxy resin can be epoxy resin 862. For the above bisphenol F epoxy resin, resin manufacturers include Dow, HUNTSMAN, etc. The amount of bisphenol F epoxy resin can be 20, 40, 60, 80, 90, etc. parts by weight.

[0032] The oxazolidinone epoxy resin is used to improve the moisture and heat resistance and rigidity. The oxazolidinone epoxy resin can be Dow's 6508. The amount of the oxazolidinone epoxy resin can be 5, 10, 15, 20 parts by weight.

[0033] Hyperbranched polymers are used to reduce internal stress and improve toughness. Hyperbranched polymers can be polyether polyols. Domestic resin manufacturers include Wuhan Hyperbranched Resin Technology Co., Ltd. and the like. The amount of hyperbranched polymer can be 0, 1, 3, 5, etc. parts by weight.

[0034] Nano core-shell polymer is used to reduce internal stress and improve toughness. Nano core-shell polymer can be produced by Japan's Kanebuchi. The amount of nano core-shell polymer can be 0, 1, 3, 5, etc. parts by weight.

[0035] The rheological additive is used to resist micro cracks and prevent glue shortage. The rheological additive can be a sheet silicate. The rheological additive can be BYK's GARAMITE-1958. The amount of the rheological additive can be 0, 1, 2 parts by weight.

[0036] The curing agent is used for curing the resin. The curing agent can be 2-ethyl-4-methylimidazole. The amount of the curing agent can be 2, 3, 4, 5, etc. parts by weight.

[0037] The present invention reduces the polar groups in the molecular structure of the resin epoxy resin matrix by adding oxazolidone epoxy resin, reduces the interaction between the resin matrix and water, and thus reduces the water absorption of the resin matrix. The present invention improves the wet and thermal properties of the material by introducing heat-resistant groups such as oxazolidone epoxy resin and other low water absorption, high temperature resistant, and rigid and tough materials into the resin system. The present invention can improve the weather resistance of the epoxy resin system and reduce the viscosity of the system by adding epoxy resin with good weather resistance, such as bisphenol F epoxy resin, into the system. The present invention reduces the internal stress of the epoxy resin system during the curing and application process and increases the toughness of the material by adding hyperbranched polymers into the system. Among them, the polyether polyol hyperbranched polymer is less added than conventional toughening materials, and the improved performance is significant, avoiding the problems of increased viscosity, large addition quantity, and reduced heat resistance of the material brought by conventional toughening materials. The present invention can improve the anti-crack ability of the material and the anti-sagging performance of the resin by adding a rheological additive-sheet silicate into the system as needed, thereby preventing excessive loss of resin during operation, resulting in defects such as glue shortage and bubbles.

[0038] An embodiment of the present invention further provides a method for preparing the above-mentioned dry-type reactor encapsulation insulating epoxy resin system, comprising the following steps:

[0039] In a vacuum environment, electronic grade epoxy resin and bisphenol F epoxy resin are added into a mixer, stirred at a low speed for 10 to 20 minutes at 40 to 100° C., then oxazolidone epoxy resin, hyperbranched polymer, nano core-shell polymer and rheological additive are added, stirred at a low speed for 30 to 60 minutes, then cooled to 40 to 50° C., a curing agent is added, stirred for 5 to 15 minutes, and the material is discharged to obtain a dry-type reactor encapsulation insulating epoxy resin system.

[0040] Among them, after adding the electronic grade epoxy resin and bisphenol F epoxy resin to the mixer, stirring can be carried out at a temperature of 40, 60, 80, 100°C. After adding the electronic grade epoxy resin and bisphenol F epoxy resin to the mixer, stirring can be carried out for 10, 15, 20 minutes, etc. After adding the oxazolidinone epoxy resin, hyperbranched polymer, nano core-shell polymer, and rheological additive, stirring can be carried out for 30, 40, 50, 60 minutes, etc. The temperature can be lowered to 40, 45, 50°C, etc. before adding the curing agent. After adding the curing agent, stirring can be carried out for 5, 8, 10, 15 minutes, etc.

[0041] Before using the electronic grade epoxy resin, heat the electronic grade epoxy resin to a lower viscosity above 40°C.

[0042] Before using the curing agent, heat the curing agent to a molten state above 35°C.

[0043] The resin mixing can be continuous or intermittent. For intermittent mixing, a double planetary vacuum mixer is recommended.

[0044] The present invention reduces the volatile matter and bubbles in the epoxy resin system by optimizing the mixing process of the epoxy resin, thereby ensuring the mixing uniformity of the system materials.

[0045] In general, the dry-type reactor encapsulated insulating epoxy resin system of the present invention can improve the moisture and heat resistance and toughness of current epoxy resin insulating materials, reduce microcracks and water absorption of epoxy resin insulating materials, improve the insulating capacity of insulating materials, and improve the impact resistance, short-circuit resistance and insulation performance of the reactor. The dry-type reactor encapsulated insulating epoxy resin system of the present invention can overcome the problems of large brittleness, easy cracking and water absorption, and poor weather resistance of the encapsulated insulating layer of the existing reactor during outdoor operation. The dry-type reactor encapsulated insulating epoxy resin system of the present invention can ensure that the coil has excellent sealing integrity, resistance to thermal expansion and contraction, insulation, weather resistance, and crack resistance, thereby ensuring excellent electrical machinery and electrical performance and reducing the risk of power grid accidents.

[0046] The following is a detailed description with reference to specific embodiments:

[0047] Example 1

[0048] formula:

[0049] 60 parts by weight of electronic grade epoxy resin, 40 parts by weight of bisphenol F epoxy resin, 10 parts by weight of oxazolidinone epoxy resin, 2 parts by weight of hyperbranched polymer, 2 parts by weight of nano core-shell polymer, 3 parts by weight of curing agent and 1 part by weight of rheological additive.

[0050] Preparation process:

[0051] In a vacuum environment, electronic grade epoxy resin and bisphenol F epoxy resin are added to the mixer, stirred at low speed for 15 minutes at 60°C, and then oxazolidinone epoxy resin, hyperbranched polymer, nano core-shell polymer, and rheological additive are added, stirred at low speed for 50 minutes, then cooled to 45°C, a curing agent is added, vacuumed and stirred for 15 minutes, and the material is discharged to obtain a dry-type reactor encapsulation insulation epoxy resin system. Before using the electronic grade epoxy resin, the electronic grade epoxy resin is heated to a lower viscosity above 40°C. Before using the curing agent, the curing agent needs to be heated to a molten state above 35°C.

[0052] Example 2

[0053] formula:

[0054] 70 parts by weight of electronic grade epoxy resin, 30 parts by weight of bisphenol F epoxy resin, 15 parts by weight of oxazolidinone epoxy resin, 1 part by weight of hyperbranched polymer, 1 part by weight of nano core-shell polymer, 3 parts by weight of curing agent, and 0.5 parts by weight of rheological additive.

[0055] Preparation process:

[0056] In a vacuum environment, electronic grade epoxy resin and bisphenol F epoxy resin are added to the mixer, stirred at low speed for 10 minutes at 40°C, and then oxazolidinone epoxy resin, hyperbranched polymer, nano core-shell polymer, and rheological additive are added, stirred at low speed for 30 minutes, then cooled to 40°C, a curing agent is added, vacuum stirred for 15 minutes, and the material is discharged to obtain a dry-type reactor encapsulation insulation epoxy resin system. Before using the electronic grade epoxy resin, the electronic grade epoxy resin is heated to a lower viscosity above 40°C. Before using the curing agent, the curing agent is heated to a molten state above 35°C.

[0057] Example 3

[0058] formula:

[0059] 80 parts by weight of electronic grade epoxy resin, 20 parts by weight of bisphenol F epoxy resin, 20 parts by weight of oxazolidinone epoxy resin, 3 parts by weight of hyperbranched polymer, 5 parts by weight of nano core-shell polymer, 3 parts by weight of curing agent, and 0.2 parts by weight of rheological additive.

[0060] Preparation process:

[0061] In a vacuum environment, electronic grade epoxy resin and bisphenol F epoxy resin are added to a mixer, stirred at low speed for 20 minutes at 100°C, and then oxazolidinone epoxy resin, hyperbranched polymer, nano core-shell polymer, and rheological additive are added, stirred at low speed for 60 minutes, then cooled to 50°C, a curing agent is added, vacuumed and stirred for 15 minutes, and the material is discharged to obtain a dry-type reactor encapsulation insulating epoxy resin system. Before using the electronic grade epoxy resin, the electronic grade epoxy resin is heated to a lower viscosity of more than 40°C. Before using the curing agent, the curing agent is heated to a molten state of more than 35°C.

[0062] Comparative Example 1

[0063] The only difference from Example 1 is that no oxazolidinone epoxy resin is added.

[0064] Comparative Example 2

[0065] The only difference from Example 1 is that no rheology additive is added.

[0066] Comparative Example 3

[0067] The only difference from Example 1 is that no hyperbranched polymer and nano core-shell polymer are added.

[0068] The formulas of the above embodiments and comparative examples are as follows:

[0069]

[0070]

[0071] The performance of the system obtained in the above examples and comparative examples is as follows:

[0072] performance Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 <![CDATA[Izod impact (KJ / m 2 )]]> 18 18.5 19 16 15.8 14 Glass transition temperature(℃) 162 165 167 160 162 162 Water absorption (%) 0.10 0.09 0.08 0.14 0.10 0.12

[0073] Among them, simply supported beam impact strength (unnotched): test instrument: impact testing machine. Test method and sample size: in line with national standard GB / T 1451-2005, 80×10×4mm;

[0074] Glass transition temperature: Test instrument: differential calorimeter. Test method and sample size: in accordance with national standard GB / T22567-2008, solidified material crushing, N2 protection, 10℃ / min;

[0075] Water absorption: Test instruments: balance, oven, constant temperature water bath, desiccator. Test method and sample size: in accordance with national standard GB / T 1034-2008, 60×60×1mm.

[0076] Comparing the performance of the system obtained in Example 1 and Comparative Example 1, it can be seen that the present invention improves the simply supported beam impact strength and glass transition temperature and reduces the water absorption rate by adopting oxazolidinone epoxy resin. Comparing the performance of the system obtained in Example 1 and Comparative Example 2, it can be seen that the present invention improves the simply supported beam impact strength by adopting a rheological additive. Comparing the performance of the system obtained in Example 1 and Comparative Example 3, it can be seen that the present invention improves the simply supported beam impact strength by adopting a hyperbranched polymer and a nano core-shell polymer.

[0078] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A dry-type reactor encapsulation insulation epoxy resin system, characterized in that: Includes the following components: 40-90 parts by weight of electronic grade epoxy resin, 20-90 parts by weight of bisphenol F epoxy resin, 5-20 parts by weight of oxazolidinone epoxy resin, and 2-5 parts by weight of curing agent.

2. The dry-type reactor encapsulation insulating epoxy resin system according to claim 1, characterized in that: Also includes the following components: 0-5 parts by weight of hyperbranched polymer and 0-5 parts by weight of nano core-shell polymer; wherein the weight of the hyperbranched polymer and the nano core-shell polymer are not 0.

3. The dry-type reactor encapsulation insulating epoxy resin system according to claim 1, characterized in that: Also includes the following components: 0 to 2 parts by weight of rheological additive; wherein the weight of the rheological additive is not 0.

4. The dry-type reactor encapsulation insulating epoxy resin system according to claim 2, characterized in that: The hyperbranched polymer includes a polyether polyol.

5. The dry-type reactor encapsulation insulating epoxy resin system according to claim 3, characterized in that: The rheology modifier includes sheet silicate.

6. The dry-type reactor encapsulation insulating epoxy resin system according to claim 1, characterized in that: The curing agent includes 2-ethyl-4-methylimidazole.

7. A method for preparing the epoxy resin system for encapsulating the dry-type reactor according to any one of claims 1 to 6, characterized in that: The following steps are involved: In a vacuum environment, electronic grade epoxy resin and bisphenol F epoxy resin are stirred at 40-100° C. for 10-20 minutes, and then oxazolidone epoxy resin is added and stirred for 30-60 minutes. Then the temperature is lowered to 40-50° C., a curing agent is added, and stirred for 5-15 minutes. The material is discharged to obtain a dry-type reactor encapsulation insulating epoxy resin system.

8. The preparation method according to claim 7, characterized in that: When the oxazolidinone epoxy resin is added, a hyperbranched polymer and a nano core-shell polymer are also added.

9. The preparation method according to claim 7, characterized in that: When the oxazolidinone epoxy resin is added, a rheological additive is also added.

10. The preparation method according to claim 7, characterized in that: Before using the electronic grade epoxy resin, the electronic grade epoxy resin is heated to above 40°C.

11. The preparation method according to claim 7, characterized in that: Before using the curing agent, heat the curing agent to above 35°C.

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