Epoxy anhydride resin capable of being subjected to VPI impregnation repeatedly and formed winding comprising epoxy anhydride resin

Abstract

The invention discloses epoxy anhydride resin capable of being subjected to VPI impregnation repeatedly and a formed winding containing the epoxy anhydride resin, and the epoxy anhydride resin comprises the following components in parts by weight: 10-20 parts of dynamic bond epoxy resin, 30-40 parts of non-dynamic bond epoxy resin, 40-49 parts of an anhydride curing agent and 0.01-1 part of a latent curing agent, the dynamic bond epoxy resin is shown as a formula I: # imgabs0 # formula I, wherein n is greater than or equal to 1; the dynamic bond epoxy resin in the epoxy anhydride resin contains ester bonds with dynamic reaction activity, and the ester bonds with the dynamic reaction activity are distributed in network three-dimensional macromolecular resin generated through cross-linking curing reaction in the baking reaction curing stage of impregnated resin and can be degraded after being heated in an amine solution, so that the dynamic bond epoxy resin can be used for curing the network three-dimensional macromolecular resin. The technical problems that the insulating impregnating resin cannot be degraded, the molded winding insulating structure thinning VPI manufacturability is difficult to verify, and the electromagnetic wire is recycled in a lossless mode are solved.

Description

Technical Field

[0001] The invention relates to the technical field of insulating impregnated resins, and in particular to an epoxy anhydride resin capable of repeated VPI impregnation and a molded winding containing the same. Background Art

[0002] With the rapid development of high-voltage large motors and variable-frequency motors, the requirements for insulating materials are gradually increasing. Not only are excellent comprehensive properties such as electrical properties and mechanical properties required, but higher requirements are also placed on the thinning of the insulation structure and the improvement of electrical strength.

[0003] At present, the single-side insulation thickness of 10kV high-voltage motors has been reduced to 1.8mm, and further reduced to 1.6mm or even 1.4mm, and its processability still needs to be verified. Impregnation resin is a thermosetting resin. After the VPI impregnation and baking curing of the molded winding, if the insulation performance cannot meet the requirements, the winding has to be violently disassembled to recycle the electromagnetic wire, resulting in long manufacturing time and huge losses.

[0004] Therefore, it is necessary to provide a technical solution to solve the problems in the prior art that the insulating impregnation resin cannot be degraded, the processability verification of the thinning VPI of the molded winding insulation structure is difficult, and the electromagnetic wire recycling is difficult. Summary of the invention

[0005] In view of this, the present application provides a repeatable VPI-impregnated epoxy anhydride resin and a molded winding containing the same, which are used to solve the technical problems of how to overcome the non-degradability of the insulating impregnating resin, the difficulty in verifying the VPI processability of the thinning insulation structure of the molded winding, and the lossless recovery of the electromagnetic wire.

[0006] In order to achieve the above technical objectives, this application adopts the following technical solutions: In a first aspect, the present application provides an epoxy anhydride resin capable of repeated VPI impregnation, wherein the components thereof include, by weight: 10-20 parts of a dynamic bond epoxy resin, 30-40 parts of a non-dynamic bond epoxy resin, 40-49 parts of an anhydride curing agent, and 0.01-1 parts of a latent curing agent; the dynamic bond epoxy resin is as shown in Formula I: Formula I, wherein n≥1.

[0007] Preferably, the non-dynamic bond epoxy resin includes one or more of bisphenol F epoxy resin and bisphenol A epoxy resin.

[0008] Preferably, the anhydride curing agent includes one or more of tung oil anhydride, methyl hexahydrophthalic anhydride, methyl nadic anhydride, and hydrogenated methyl nadic anhydride.

[0009] Preferably, the latent curing agent includes one or more of zinc acetate, zinc cyclohexane, zinc isooctanoate, chromium acetylacetonate, and boron trifluoride ethylamine.

[0010] Preferably, the preparation method of the dynamic bond epoxy resin is as follows: using bisphenol A and malonic acid as raw materials, using tetrabutyl titanate as a catalyst, heating to 120°C~200°C for reaction for 4~10 hours, washing with water until neutral, then adding epichlorohydrin under NaOH catalysis, heating to 100~110°C for reaction for 5~12 hours, washing with water until neutral, and obtaining the dynamic bond epoxy resin.

[0011] In a second aspect, the present application provides a molded winding comprising electromagnetic wire, mica tape, alkali-free glass fiber tape, low-resistance tape, high-resistance tape, and epoxy anhydride resin that can be repeatedly VPI-impregnated.

[0012] In a third aspect, the present application provides a method for preparing a formed winding, comprising the following steps: S1. Using three parallel winding and / or half-lapping process, the winding matrix is ​​prepared with electromagnetic wire, mica tape, alkali-free glass fiber tape, low resistance tape, and high resistance tape as raw materials; S2. The winding matrix is ​​placed in a vacuum environment, and then the winding matrix is ​​impregnated under pressure into a repeatable VPI impregnation epoxy anhydride resin, and then dried and cured to obtain a molded winding.

[0013] Preferably, in step S2, the vacuum degree of the vacuum environment is 50-60Pa, and the standing time is 5-7h; the pressure of the pressurized impregnation is 0.5-0.6Mpa, and the pressurized impregnation time is 7-10h; the curing temperature is 150-170°C, and the curing time is 12-16h.

[0014] In a fourth aspect, the present application provides a method for recycling electromagnetic wires from formed windings, comprising the following steps: immersing the formed windings in an amine solution, heating and degrading the solution, and thereby recycling the electromagnetic wires.

[0015] Preferably, the temperature for heating degradation is 80-150° C. and the time is 1-24 h.

[0016] The beneficial effects of the present application are as follows: the dynamic bond epoxy resin in the epoxy anhydride resin of the present application contains dynamically reactive ester bonds. During the impregnation resin baking reaction curing stage, the dynamically reactive ester bonds are distributed in the network three-dimensional macromolecular resin generated by the cross-linking curing reaction, which has the characteristics of high bonding strength, low dielectric loss factor and good heat resistance when the motor is operating normally; during the process verification and maintenance stages, when the local discharge, leakage current and other properties of the winding impregnated with VPI cannot meet the requirements, the decomposition effect can be achieved by immersing the winding in an alkaline amine degradation solution, and the electromagnetic wire can be taken out intact and rewrapped with mica tape into a molded winding, and VPI impregnation is performed again, which effectively solves the problem that the existing molded winding cannot be repeatedly VPI impregnated during the process verification and maintenance stages, and can only destroy all wires and their insulation structures, resulting in a long manufacturing cycle and large losses. DETAILED DESCRIPTION

[0017] 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.

[0018] The present application provides an epoxy anhydride resin capable of repeated VPI impregnation, wherein the components thereof include, by weight: 10-20 parts of a dynamic bond epoxy resin, 30-40 parts of a non-dynamic bond epoxy resin, 40-49 parts of an anhydride curing agent, and 0.01-1 part of a latent curing agent; the dynamic bond epoxy resin is as shown in Formula I: Formula I, wherein n≥1.

[0019] In the present application, the dynamic bond epoxy resin can stably exist in an environment such as room temperature and pressure, but can be degraded and recycled when exposed to external stimuli (such as temperature, chemicals or photolysis). The dynamic bond epoxy resin of the present application will undergo ester exchange reaction and Diels-Alder reaction after heating; the dynamic epoxy resin of the present application has enough ester bonds, and the molecular weight decreases during degradation, which can reduce the mechanical strength and is conducive to the decomposition of the epoxy anhydride resin.

[0020] In some embodiments, the non-dynamic bond epoxy resin includes one or more of bisphenol F epoxy resin and bisphenol A epoxy resin.

[0021] In some embodiments, the anhydride curing agent includes one or more of tung oil anhydride, methyl hexahydrophthalic anhydride, methyl nadic anhydride, and hydrogenated methyl nadic anhydride.

[0022] In some embodiments, the latent curing agent includes one or more of zinc acetate, zinc cyclohexane, zinc isooctanoate, chromium acetylacetonate, and ethylamine boron trifluoride.

[0023] In some embodiments, the preparation method of dynamic bond epoxy resin is as follows: 1.05 mol of bisphenol A and 1 mol of malonic acid are put into a three-necked flask, tetrabutyl titanate is added as a catalyst, heated to 120°C~200°C for reaction for 4~10 hours, washed with water until neutral, 2 mol of epichlorohydrin is added, heated to 100~110°C for reaction for 5~12 hours under the catalysis of NaOH, washed with water until neutral and set aside.

[0024] In a second aspect, the present application provides a molded winding comprising electromagnetic wire, mica tape, alkali-free glass fiber tape, low-resistance tape, high-resistance tape, and epoxy anhydride resin that can be repeatedly VPI-impregnated.

[0025] In some embodiments, the mica tape includes one or more of the following commercially available glass cloth reinforced mica tape with less rubber powder, polyester film reinforced mica tape with less rubber powder, and polyimide film reinforced mica tape with less rubber powder. The mica tape also includes an epoxy accelerator, which includes but is not limited to one or more of zinc acetate, zinc naphthenate, zinc isooctanoate, chromium acetylacetonate, and boron trifluoride ethylamine. The mica tape is composed of mica paper, adhesive, and reinforcing material (glass cloth, film, etc.), and the accelerator is contained in the adhesive.

[0026] In a third aspect, the present application provides a method for preparing a formed winding, comprising the following steps: S1. Using three parallel winding and / or half-lapping process, the winding matrix is ​​prepared with electromagnetic wire, mica tape, alkali-free glass fiber tape, low resistance tape, and high resistance tape as raw materials; S2. The winding matrix is ​​placed in a vacuum environment, and then the winding matrix is ​​impregnated under pressure into a repeatable VPI impregnation epoxy anhydride resin, and then dried and cured to obtain a molded winding.

[0027] In some embodiments, in step S2, the vacuum degree of the vacuum environment is 50-60Pa, and the standing time is 5-7h; the pressure of the pressurized impregnation is 0.5-0.6Mpa, and the pressurized impregnation time is 7-10h; the curing temperature is 150-170°C, and the curing time is 12-16h. The three-wire parallel winding and half-lapping process are well known to those skilled in the art.

[0028] The dynamic bond epoxy resin of the present application contains dynamic covalent bonds. During the curing stage of the impregnated resin baking reaction, the dynamically reactive ester bonds are distributed in the network three-dimensional macromolecular resin generated by the cross-linking curing reaction. When the motor is operating normally, it has the characteristics of high bonding strength, low dielectric loss factor and good heat resistance. During the process verification stage, when the local discharge, leakage current and other properties of the winding impregnated with VPI cannot meet the requirements, the decomposition effect can be achieved by immersing the winding in an amine degradation liquid. The electromagnetic wire can be taken out intact and rewrapped with mica tape into a molded winding, and VPI impregnation is performed again, which effectively solves the problem that the existing molded winding cannot be repeatedly impregnated with VPI during the process verification and repair stages, and can only destroy all the wires and their insulation structures, resulting in a long manufacturing cycle and large losses.

[0029] In a fourth aspect, the present application provides a method for recycling electromagnetic wires from formed windings, comprising the following steps: immersing the formed windings in an amine solution, heating and degrading the solution, and thereby recycling the electromagnetic wires.

[0030] In the amine solution, the epoxy anhydride resin of the present application is heated and degraded, losing viscosity and strength, and the electromagnetic wire can be directly taken out and recycled without violently disassembling the formed winding. The amine solution includes but is not limited to one or more of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and N-methylpyrrolidone.

[0031] Preferably, the temperature for heating degradation is 80-150° C. and the time is 1-24 h.

[0032] The present solution is further described below through specific embodiments.

[0033] Raw material preparation Dynamic bond epoxy resin: put 1.05 mol bisphenol A and 1 mol malonic acid into a three-necked flask, add tetrabutyl titanate as a catalyst, heat to 120℃~200℃ and react for 4~10 hours, wash with water until neutral, add 2 mol epichlorohydrin, heat to 100~110℃ and react for 5~12 hours under the catalysis of NaOH, wash with water until neutral and set aside.

[0034] Example 1 A reproducible VPI impregnated epoxy anhydride resin, comprising, by weight, 15 parts of a dynamic bond epoxy resin, 40 parts of an E51 epoxy resin, 44 parts of methyl hexahydrophthalic anhydride, and 1 part of zinc acetate; the dynamic bond epoxy resin is as shown in Formula I: Formula I, wherein n=2.

[0035] Example 2 A reproducible VPI impregnated epoxy anhydride resin, comprising, by weight, 20 parts of a dynamic bond epoxy resin, 35 parts of an E44 epoxy resin, 44.5 parts of tung oil anhydride, and 0.5 parts of zinc cyclohexane; the dynamic bond epoxy resin is as shown in Formula I: Formula I, wherein n=2.

[0036] Example 3 A reproducible VPI impregnated epoxy anhydride resin, comprising, by weight, 10 parts of a dynamic bond epoxy resin, 40 parts of an E51 epoxy resin, 49 parts of methyl hexahydrophthalic anhydride, and 1 part of zinc acetate; the dynamic bond epoxy resin is as shown in Formula I: Formula I, wherein n=2.

[0037] Example 4 A reproducible VPI impregnated epoxy anhydride resin, comprising, by weight, 17 parts of a dynamic bond epoxy resin, 38 parts of an F170 epoxy resin, 44.5 parts of methyl nadic anhydride, and 0.05 parts of zinc acetate; the dynamic bond epoxy resin is as shown in Formula I: Formula I, wherein n=2.

[0038] Example 5 A forming winding, the preparation raw materials include polyimide film sintered wire, glass cloth reinforced low-rubber powder mica tape, polyester film reinforced low-rubber powder mica tape, polyimide film reinforced low-rubber powder mica tape, low-resistance tape, high-resistance tape, and the epoxy anhydride resin prepared in Example 1 that can be repeatedly VPI-impregnated; the preparation steps are as follows: S1. Three MYFB-2 polyimide film sintered wires are wound together to make a coil, and then half-wrapped with 7 layers of glass cloth reinforced with less rubber powder mica tape, half-wrapped with 1 layer of low-resistance tape for the straight part, and half-wrapped with 1 layer of high-resistance tape with an overlap of about 20cm to make a winding matrix; S2. Pre-bake the winding substrate, cool it to 45°C, and then put it into a paint dipping tank. Evacuate it to below 50Pa and keep it for 6 hours. Input the epoxy anhydride resin that can be repeatedly impregnated with VPI into the paint dipping tank, pressurize it to 0.5Mpa~0.6Mpa and keep it for 10 hours. Put the impregnated molded winding into an oven, heat it to 160°C and keep it for 14 hours for curing to obtain the molded winding.

[0039] Example 6 A formed winding, the other contents are the same as those of Example 5, except that in step S1, after three MYFB-2 polyimide film sintered wires are wound together to make a coil, 4 layers of glass cloth reinforced mica tape with little rubber powder and 3 layers of polyester film reinforced mica tape with little rubber powder are half-wrapped in sequence.

[0040] Example 7 A formed winding, the other contents are the same as those of Example 5, except that in step S1, after three MYFB-2 polyimide film sintered wires are wound together to make a coil, 3 layers of glass cloth reinforced mica tape with little rubber powder and 4 layers of polyester film reinforced mica tape with little rubber powder are half-wrapped in sequence.

[0041] Example 8 A formed winding, the other contents are the same as those of Example 5, except that in step S1, after three MYFB-2 polyimide film sintered wires are wound together to make a coil, 4 layers of glass cloth reinforced mica tape with little rubber powder and 3 layers of polyimide film reinforced mica tape with little rubber powder are half-wrapped in sequence.

[0042] Example 9 A formed winding, the other contents are the same as those of Example 5, except that in step S1, after three MYFB-2 polyimide film sintered wires are wound together to make a coil, 3 layers of glass cloth reinforced mica tape with little rubber powder and 4 layers of polyimide film reinforced mica tape with little rubber powder are half-wrapped in sequence.

[0043] Comparative Example 1 An epoxy anhydride resin comprises, by weight, 50 parts of E51 epoxy resin, 49.8 parts of methylhexahydrophthalic anhydride, and 0.2 parts of zinc acetate.

[0044] Test and Evaluation The epoxy anhydride resins provided in Examples 1-4 and Comparative Example 1 were mixed and cured at 150° C. for 6 hours. The conventional properties of the obtained resins were tested, and the degradability was evaluated using an amine solution at 130° C. The results are shown in Table 1.

[0045] Table 1 Performance test results of epoxy anhydride resin

[0046] The above results indicate that the higher the content of dynamic bond epoxy resin, the shorter the time required for degradation in amine solution, the epoxy anhydride impregnated resin without dynamic bond epoxy resin is not degradable, and the epoxy anhydride resin of Example 1 of the present application has better comprehensive performance.

[0047] The insulation structures of the formed windings of Examples 5-9 are summarized as shown in Table 2.

[0048] Table 2 Manufacturing method of the formed winding insulation structure of Examples 5-9

[0049] The performance indicators of the formed windings of Examples 5-9 were tested, and the results are shown in Table 3.

[0050] Table 3 Performance test results of the formed windings of Examples 5-9

[0051] It can be seen from Examples 5-9 that for conventional 10kV formed winding insulation structures, the formed winding impregnated in Example 1 can meet the requirements for performance, and can be degraded in an amine solution to remove the electromagnetic wire without loss. When the processability, insulation structure design, etc. cannot meet the performance requirements, the electromagnetic wire can be removed without loss, the formed winding can be remade and VPI impregnated again, which effectively solves the problem that the existing formed winding cannot be repeatedly impregnated with VPI during the process verification stage and the repair stage, and can only destroy all the wires and their insulation structures, resulting in a long manufacturing cycle and large losses.

[0052] The above are only preferred specific implementations of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. An epoxy anhydride resin capable of repeated VPI impregnation, characterized in that: The components thereof include, by weight: 10-20 parts of dynamic bond epoxy resin, 30-40 parts of non-dynamic bond epoxy resin, 40-49 parts of anhydride curing agent, and 0.01-1 part of latent curing agent; the dynamic bond epoxy resin is as shown in Formula I: Formula I, wherein n≥1.

2. The epoxy anhydride resin capable of repeated VPI impregnation according to claim 1, characterized in that The non-dynamic bond epoxy resin includes one or more of bisphenol F epoxy resin and bisphenol A epoxy resin.

3. The epoxy anhydride resin capable of repeated VPI impregnation according to claim 1, characterized in that: The acid anhydride curing agent includes one or more of tung oil anhydride, methyl hexahydrophthalic anhydride, methyl nadic anhydride, and hydrogenated methyl nadic anhydride.

4. The epoxy anhydride resin capable of repeated VPI impregnation according to claim 1, characterized in that: The latent curing agent includes one or more of zinc acetate, zinc cyclohexane, zinc isooctanoate, chromium acetylacetonate, and boron trifluoride ethylamine.

5. The epoxy anhydride resin capable of repeated VPI impregnation according to claim 1, characterized in that: The preparation method of the dynamic bond epoxy resin is as follows: using bisphenol A and malonic acid as raw materials, using tetrabutyl titanate as a catalyst, heating to 120°C~200°C for reaction for 4~10 hours, washing with water until neutral, then adding epichlorohydrin under the catalysis of NaOH, heating to 100~110°C for reaction for 5~12 hours, washing with water until neutral, and obtaining the dynamic bond epoxy resin.

6. A formed winding, characterized in that: The invention comprises electromagnetic wire, mica tape, alkali-free glass fiber tape, low-resistance tape, high-resistance tape, and the epoxy anhydride resin capable of repeated VPI impregnation as claimed in any one of claims 1 to 5.

7. A method for preparing a formed winding according to claim 6, characterized in that: The following steps are involved: S1. Using three parallel winding and / or half-lapping process, the winding matrix is ​​prepared with electromagnetic wire, mica tape, alkali-free glass fiber tape, low resistance tape, and high resistance tape as raw materials; S2. The winding matrix is ​​placed in a vacuum environment, and then the winding matrix is ​​impregnated under pressure into the epoxy anhydride resin that can be repeatedly impregnated with VPI, and then dried and cured to obtain the molded winding.

8. The method for preparing a formed winding according to claim 7, characterized in that: In step S2, the vacuum degree of the vacuum environment is 50-60Pa, and the standing time is 5-7h; the pressure of the pressurized impregnation is 0.5-0.6Mpa, and the pressurized impregnation time is 7-10h; the curing temperature is 150-170°C, and the curing time is 12-16h.

9. A method for recovering electromagnetic wire using the formed winding as claimed in claim 6, characterized in that: The following steps are involved: The formed winding is immersed in an amine solution and heated to degrade, thereby obtaining the recovered electromagnetic wire.

10. The method according to claim 9, characterized in that The temperature of the heating degradation is 80-150° C. and the time is 1-24 hours.

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