Single-sided glue-rich mica tape capable of being molded for multiple times and application thereof

Abstract

The invention discloses a single-sided adhesive-rich mica tape capable of being molded for multiple times, which is composed of an isolating membrane, a mica paper layer and alkali-free glass fiber cloth impregnated with an adhesive, the adhesive comprises 10-25 parts by weight of conventional epoxy resin, 25-40 parts by weight of epoxy resin containing dynamic covalent bonds, 40-55 parts by weight of anhydride curing agent and 0.01-1 part by weight of latent curing agent, the conventional epoxy resin is one or more of phenolic epoxy, bisphenol F type epoxy resin and bisphenol A type epoxy resin; the invention further discloses application of the composite material to preparation of the formed winding, the degraded electromagnetic wire can be taken out in a lossless mode to be recycled, and the problems that an existing formed winding cannot be repeatedly formed in the design verification stage, the repairing stage and after decommissioning, and the period is long and loss is large due to the fact that the existing formed winding can only be disassembled and damaged violently can be effectively solved.

Description

Technical Field

[0001] This invention belongs to the technical field of multi-adhesive mica products, and specifically relates to a single-sided multi-adhesive mica tape that can be formed multiple times, and its application in forming windings. Background Technology

[0002] With the rapid development of large-scale high-voltage power generation equipment in my country, the requirements for insulation materials and structures are gradually increasing. The low-adhesion VPI system has a high mica content and high electrical strength, but the VPI resin has high rigidity after curing. When the insulation thickness exceeds 3mm, it is difficult to withstand the stress generated by the repeated expansion and contraction of copper wires, so a multi-adhesion hot pressing system is required.

[0003] Multi-adhesive hot-pressing systems have high resin content, and the resin generally contains a flexible chain structure, which has high impact strength and elongation at break, effectively reducing interfacial damage with copper conductors and improving electrical insulation performance and lifespan. On the other hand, multi-adhesive hot-pressing systems have low mica content, and the insulation margin requirement is greater when designing higher voltages, resulting in a larger insulation thickness. Therefore, it is urgent to reduce the insulation structure to improve technical and economic indicators.

[0004] This requires not only that the multi-adhesive mica tape has excellent electrical and mechanical properties, but also that it can adapt to the process verification of thinning insulation.

[0005] The adhesive in multi-adhesive mica tape is a thermosetting resin. After hot pressing and curing, the winding breakdown voltage, withstand voltage, insulation resistance and other properties cannot meet the requirements. Or, due to improper operation in the expansion and hot pressing curing process, external impact, electric field, magnetic field and other factors may cause insulation damage. In addition, if the insulation performance of the winding cannot meet the requirements after the end of its service life, it is necessary to violently dismantle the winding. This causes problems such as long research and development and repair time and huge losses. Summary of the Invention

[0006] One of the objectives of this invention is to overcome the above-mentioned technical deficiencies and propose a single-sided multi-adhesive mica tape that can be formed multiple times, thereby solving the technical problems in the prior art where the adhesive hardens after hot pressing of multi-adhesive mica tape, making it impossible to disassemble, and the difficulties in designing thinner insulation structures and verifying processability.

[0007] The technical solution adopted by this invention to solve its technical problem is: a single-sided multi-adhesive mica tape that can be formed multiple times, composed of a release film, a mica paper layer, and an alkali-free glass fiber cloth impregnated with adhesive arranged in sequence; the basis weight of the mica paper layer is 230±20 g / m³. 2 The adhesive content is 85±10g / m³. 2It comprises 10-25 parts by weight of conventional epoxy resin, 25-40 parts by weight of epoxy resin containing dynamic covalent bonds, 40-55 parts by weight of acid anhydride curing agent, and 0.01-1 parts by weight of latent curing agent; the conventional epoxy resin is one or more of phenolic epoxy, bisphenol F type epoxy resin, and bisphenol A type epoxy resin; the epoxy resin containing dynamic covalent bonds has the following structural formula: In the formula, n≥1, R includes C2~C6 aliphatic chain groups and phenyl groups.

[0008] The aforementioned single-sided multi-adhesive mica tape, which can be formed multiple times, has a mica paper layer with a mica content of 100-140 g / m³. 2 Calcined mica paper between.

[0009] The single-sided multi-adhesive mica tape that can be formed multiple times has an anhydride curing agent that is one or more of tung oil anhydride, tung horse anhydride, methyl nadic anhydride, and dodecenyl succinic anhydride.

[0010] The single-sided multi-adhesive mica tape that can be formed multiple times has a latent curing agent that is one or more of zinc naphthenate, zinc isooctanoate, stannous octoate, boron trifluoride ethylamine, and boron trichloride monoethylamine.

[0011] The second objective of this invention is to propose the application of the aforementioned single-sided multi-adhesive mica tape, which can be formed multiple times, in molded windings for the preparation of molded windings.

[0012] Furthermore, the molded winding is composed of electromagnetic wire, multi-adhesive mica tape, low-resistance tape, and high-resistance tape.

[0013] Furthermore, the preparation method includes the following steps:

[0014] Step 1: Wind the electromagnetic wire into the designed shape and press it into shape;

[0015] Step 2: After removing the release film from the single-sided multi-adhesive mica tape, wrap it around the electromagnetic wire;

[0016] Step 3: Wrap the low-resistance and high-resistance bands;

[0017] Step 4: Place the winding in a special heating mold and heat it to 165℃~185℃, apply pressure of 10~20MPa, maintain for 2h~6h, then cool down and demold to obtain the shaped winding.

[0018] Furthermore, when the prepared shaped winding is unqualified or damaged and needs to be disassembled and remade, the shaped winding that has been wrapped and hot-pressed is heated in a degradation solution to degrade and solidify the adhesive. The winding is then removed from the motor core without damage, the mica paper layer is disassembled, and the electromagnetic wire is separated.

[0019] Furthermore, the degradation solution comprises one or more of the following: ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, hexamethylenediamine, isophoronediamine, 1,3-cyclohexanedimethylamine, ethylene glycol, butanediol, hexanediol, benzyl alcohol, zinc acetate, zinc naphthenate, zinc isooctanoate, stannous octoate, and antimony trichloride.

[0020] Furthermore, the heating temperature range in the degradation solution is 100–160°C, and the time is 1–24 hours.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] The single-sided multi-adhesive mica tape provided by this invention has dynamic covalent bonds in the adhesive. During the hot pressing and curing stage, the reactive dynamic covalent bonds are distributed in the cross-linking curing reaction to form a network of three-dimensional macromolecular resin. Under normal motor operation, it has the characteristics of high electrical strength, low dielectric loss factor and resistance to thermal shock.

[0023] When this invention is used to prepare shaped windings, if the breakdown voltage, withstand voltage, insulation resistance, and other properties of the winding cannot meet the requirements after hot pressing during the design verification stage, or if damage occurs due to improper operation during the expansion and hot pressing curing process, external impacts, electric fields, magnetic fields, etc., or after the winding has reached the end of its service life and has been decommissioned, the winding can be decomposed by immersing it in an amine degradation solution. The electromagnetic wire can be removed intact without damage, and the winding can be re-wound with multiple tapes to form a shaped winding, and then hot-pressed again. This effectively solves the problem that existing windings cannot be re-formed during the design verification stage, repair stage, and after decommissioning, and can only destroy all electromagnetic wires and their insulation structure, resulting in long manufacturing cycles and large losses. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0025] This invention discloses a single-sided multi-adhesive mica tape that can be formed multiple times, comprising a release film, a mica paper layer, and an alkali-free glass fiber cloth impregnated with adhesive arranged in sequence; the basis weight of the mica paper layer is 230±20 g / m³. 2 The adhesive content is 85±10g / m³. 2 It comprises 10-25 parts by weight of conventional epoxy resin, 25-40 parts by weight of epoxy resin containing dynamic covalent bonds, 40-55 parts by weight of acid anhydride curing agent, and 0.01-1 parts by weight of latent curing agent; wherein the conventional epoxy resin is one or more of phenolic epoxy, bisphenol F type epoxy resin, and bisphenol A type epoxy resin; wherein the epoxy resin containing dynamic covalent bonds is as shown in Formula I: In the formula, n≥1, R includes C2~C6 aliphatic chain groups and phenyl groups.

[0026] The adhesive of this invention is impregnated with alkali-free glass fiber cloth and then penetrates into mica paper, serving to bond the mica paper and alkali-free glass fiber cloth and improve the overall integrity of the mica paper. During the hot pressing process, the adhesive cures upon heating, and its properties directly determine the electrical, thermal, and mechanical properties of the mica, directly affecting the safe and stable operation of the unit.

[0027] Examples 1-4 and Comparative Example 5 provide the compositions of different reproducible single-sided multi-adhesive mica tapes and compare them with conventional multi-adhesive mica tapes. The component mass percentages are shown in the table below. The table below shows the composition and weight parts of each raw material of the multi-adhesive mica tape adhesive in Examples 1-4 and Comparative Example 5.

[0028] .

[0029] The performance of the multi-adhesive mica tape was tested by curing it at 180°C for 2 hours and evaluating its biodegradability using a degradation solution at 150°C.

[0030] The table below shows the performance test results of the single-sided multi-adhesive mica tape that can be formed multiple times.

[0031] .

[0032] The higher the content of epoxy resin containing dynamic covalent bonds, the shorter the time required for degradation in the degradation solution. Conventional multi-adhesive mica tape does not have degradability. Based on comprehensive comparison, VPI impregnation of the molded winding was carried out using Example 4.

[0033] Example 6: This example uses a single-sided multi-adhesive mica tape that can be formed multiple times to prepare a shaped winding. The raw materials for preparation include: polyimide film sintered wire, single-sided multi-adhesive mica tape that can be formed multiple times, low-resistance tape, and high-resistance tape, which are prepared through the following steps.

[0034] Step 1: Wind three MYFB-2 polyimide film sintering wires together to make a coil.

[0035] Step 2: After removing the release film from the single-sided multi-adhesive mica tape that can be formed multiple times, wrap it in 12 layers in half on the electromagnetic wire.

[0036] Step 3: Half-overlap one layer of low-resistance tape on the straight section, and overlap by about 20cm to half-overlap one layer of high-resistance tape.

[0037] Step 4: Place it in a special heating mold, heat to 180℃, pressurize to 10MPa, maintain for 2 hours, then cool down and demold.

[0038] Example 7: The insulation structure of the molded winding used in this example is shown in Table 3. The difference from Example 6 is that the heating temperature in step 4 is 180°C, the pressure is 20MPa, and the heat preservation time is 2h.

[0039] Example 8: The insulation structure of the molded winding used in this example is shown in Table 3. The difference from Example 6 is that the heating temperature in step 4 is 165°C, the pressure is 10MPa, and the heat preservation time is 6h.

[0040] Example 9: The insulation structure of the molded winding used in this example is shown in Table 3. The difference from Example 6 is that the heating temperature in step 4 is 165°C, the pressure is 20MPa, and the heat preservation time is 6h.

[0041] Example 10: The insulation structure of the molded winding used in this example is shown in Table 3. The difference from Example 6 is that the heating temperature in step 4 is 170°C, the pressure is 20MPa, and the heat preservation time is 4h.

[0042] The table below shows the fabrication methods of the molded winding insulation structure in Examples 6 to 10.

[0043] .

[0044] The above-mentioned molded winding was tested, and the insulation structure performance of the molded winding is shown in the table below.

[0045] .

[0046] As can be seen from Examples 6-10, for conventional 20kV molded winding insulation structures, the molded windings produced using Example 4 all meet the performance requirements, and can be degraded in the degradation solution to the point where the mica tape can be opened and the electromagnetic wire can be removed without damage. When the insulation structure design cannot meet the performance requirements, or when insulation is damaged due to improper operation during the expansion and hot-pressing curing process, external impacts, electric fields, magnetic fields, etc., or when the insulation performance cannot meet the requirements after the winding has reached the end of its service life and is decommissioned, the electromagnetic wire can be removed without damage after degradation, and the molded winding can be re-wound with mica tape and hot-pressed to produce a molded winding. This effectively solves the problem that existing molded windings cannot be re-molded during the design verification stage, repair stage, and after decommissioning, and can only be disassembled and destroyed by force, resulting in long cycles and large losses.

[0047] 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, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A single-sided multi-adhesive mica tape that can be formed multiple times, characterized in that: It consists of a release membrane, a mica paper layer, and an alkali-free glass fiber cloth impregnated with adhesive, arranged in sequence; the basis weight of the mica paper layer is 230±20 g / m³. 2 The adhesive content is 85±10g / m³. 2 It comprises 10-25 parts by weight of conventional epoxy resin, 25-40 parts by weight of epoxy resin containing dynamic covalent bonds, 40-55 parts by weight of acid anhydride curing agent, and 0.01-1 parts by weight of latent curing agent; the conventional epoxy resin is one or more of phenolic epoxy, bisphenol F type epoxy resin, and bisphenol A type epoxy resin; the epoxy resin containing dynamic covalent bonds has the following structural formula: In the formula, n≥1, R includes C2~C6 aliphatic chain groups and phenyl groups.

2. The single-sided multi-adhesive mica tape that can be formed multiple times according to claim 1, characterized in that, The mica paper layer has a mica content of 100-140 g / m³. 2 Calcined mica paper between.

3. A single-sided multi-adhesive mica tape that can be formed multiple times according to claim 1 or 2, characterized in that, The anhydride curing agent is one or more of tung oil anhydride, tung horse anhydride, methyl nadic anhydride, and dodecenyl succinic anhydride.

4. The single-sided multi-adhesive mica tape that can be formed multiple times according to claim 3, characterized in that, The latent curing agent is one or more of zinc naphthenate, zinc isooctanoate, stannous octoate, boron trifluoride ethylamine, and boron trichloride monoethylamine.

5. The single-sided multi-adhesive mica tape that can be formed multiple times as described in any one of claims 1 to 4 is used to prepare shaped windings.

6. The application according to claim 5, characterized in that, The molded winding consists of electromagnetic wire, multi-adhesive mica tape, low-resistance tape, and high-resistance tape.

7. The application according to claim 6, characterized in that, The preparation method includes the following steps: Step 1: Wind and press the electromagnetic wire into shape; Step 2: After removing the release film from the single-sided multi-adhesive mica tape, wrap it around the electromagnetic wire; Step 3: Wrap the low-resistance and high-resistance bands; Step 4: Place the winding in a heating mold and heat it to 165℃~185℃, apply pressure of 10~20MPa, maintain for 2h~6h, then cool down and demold to obtain the shaped winding.

8. The application according to claim 7, characterized in that, When the prepared shaped winding is unqualified or damaged and needs to be disassembled and remade, the shaped winding is heated in a degradation solution to degrade the cured adhesive, and the winding is removed from the motor core without damage. The mica paper layer is then disassembled to separate the electromagnetic wire.

9. The application according to claim 8, characterized in that, The degradation solution is one or more of the following: ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, hexamethylenediamine, isophoronediamine, 1,3-cyclohexanedimethylamine, ethylene glycol, butanediol, hexanediol, benzyl alcohol, zinc acetate, zinc naphthenate, zinc isooctanoate, stannous octoate, and antimony trichloride.

10. The application according to claim 9, characterized in that, The degradation solution is heated at a temperature of 100–160°C for 1–24 hours.

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