A semi-cured glass cloth binding tape and its application

Abstract

The application relates to a semi-cured glass cloth binding belt and application thereof. The semi-cured glass cloth binding belt is formed by impregnating alkali-free glass cloth without weft with epoxy resin glue liquid, curing to B stage, and then cooling and winding. The epoxy resin glue liquid comprises liquid epoxy resin, a toughening agent, mica powder, fumed silica, a curing agent, carbon black, graphite and an active diluent, and does not contain organic solvents. The semi-cured glass cloth binding belt provided by the application has higher strength, has anti-corona performance, and has a longer service life when applied to high-voltage motors and high-voltage transformers. The semi-cured glass cloth binding belt of the application does not need to use a large amount of organic solvents, and is more environmentally friendly and safe.

Description

Technical Field

[0001] This invention specifically relates to a semi-cured glass cloth binding tape and its application. Background Technology

[0002] A large number of binding tapes are used in motors and transformers, such as for binding armature windings, rotor coils, and transformer cores. The tightness and long-term stability of these bindings directly affect the reliability of the product's operation. If the bindings are not tight or the binding strength decreases after long-term aging, it will cause greater noise and increased losses during operation.

[0003] Binding straps for motor stators and transformer cores typically include cotton tape, polyester compression tape, mesh non-woven tape, polyester rope, and fiberglass tape. While cotton and polyester non-woven binding straps are flexible, they have low mechanical strength, are prone to moisture absorption, and have poor heat resistance. Compared to cotton and polyester non-woven fabrics, fiberglass cloth has advantages such as high tensile strength, good heat resistance, and low moisture absorption. In the past, due to the high voltage and heat resistance requirements in high-voltage motors and transformers, these materials, mainly cotton, polyester non-woven fabrics, and thin silk, were gradually replaced by fiberglass. Ordinary fiberglass cloth, without treatment, has poor flexibility and is prone to bending and breakage. Currently, the common treatment method is to coat the non-woven fiberglass cloth with a layer of cured polyester resin or modified toughening epoxy resin. Among them, polyester resin has low heat resistance, usually only reaching Class B. Patent CN1034377A discloses an impregnating resin for fiberglass cloth binding tape, which can be used to produce F-grade fiberglass cloth binding tape. The impregnating resin is composed of a mixture of epoxy, curing agent, plasticizer, and acetone. Although a significant amount of plasticizer is added to the formula to adjust the flexibility of the fiberglass cloth after impregnation, the fully cured fiberglass cloth is still not soft enough for wrapping applications. Furthermore, high-voltage transformers exhibit partial discharge corrosion at the sharp corners and interlayer gaps of the binding tape, which can lead to aging and cracking of the fiberglass cloth due to resin corona corrosion over long-term use. In addition, the impregnating resin contains a large amount of volatile organic solvents, making the production process environmentally unfriendly. Summary of the Invention

[0004] The purpose of this invention is to provide a high-strength semi-cured glass cloth binding tape with conductive properties.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A semi-cured glass cloth binding tape is formed by curing non-woven, alkali-free glass cloth impregnated with epoxy resin solution to stage B, and then cooling and winding it up. The epoxy resin solution includes liquid epoxy resin, toughening modified resin, mica powder, fumed silica, curing agent, carbon black, graphite and reactive diluent. The epoxy resin solution does not contain organic solvents.

[0007] Preferably, the epoxy resin adhesive comprises the following components, based on a mass percentage of 100% in the epoxy resin solution:

[0008] Liquid epoxy resin 45%–60%;

[0009] Toughening agent 2%–6%;

[0010] 5%–10% mica powder;

[0011] Fumed silica 1%–3%;

[0012] Curing agent 8%–15%;

[0013] Carbon black 0.5%–1%;

[0014] Graphite 1%–3%;

[0015] Active diluent 5%–20%.

[0016] More preferably, based on 100% by mass of the epoxy resin adhesive, the epoxy resin adhesive comprises the following components:

[0017] Liquid epoxy resin 55%–60%;

[0018] Toughening agent 4%–6%;

[0019] Mica powder 6%–10%;

[0020] Fumed silica 1%–3%;

[0021] Curing agent 8%–10%;

[0022] Carbon black 0.5%–1%;

[0023] Graphite 1%–3%;

[0024] 10%–15% reactive diluent

[0025] Preferably, the liquid epoxy resin is a bisphenol A type epoxy resin and / or a phenolic epoxy resin.

[0026] According to some specific implementation methods, the bisphenol A type epoxy resin used is NPRL127 epoxy resin or 128 epoxy resin.

[0027] According to some specific implementation methods, the phenolic epoxy resin used is NPPL630L phenolic epoxy resin.

[0028] Preferably, the toughening agent is a liquid rubber copolymer.

[0029] More preferably, it is epoxy-terminated polybutadiene acrylonitrile (ETBN).

[0030] Preferably, the mica powder has a particle size of 5–20 μm.

[0031] Preferably, the mica powder is muscovite powder.

[0032] Preferably, the fumed silica is commercially available Aerosil R202.

[0033] Preferably, the curing agent is an amine complex of boron trichloride or boron trifluoride.

[0034] More preferably, the curing agent is boron trichloride or boron trifluoride dimethyl octylamine complex.

[0035] Preferably, the carbon black is a mixture of nano-sized acetylene and furnace-processed carbon black.

[0036] Preferably, the graphite is commercially available nanoscale graphite.

[0037] Preferably, the graphite has a particle size of 20–100 nm.

[0038] Preferably, the active diluent is glycidyl ether.

[0039] Preferably, the liquid epoxy resin is a composition of bisphenol A type epoxy resin and phenolic epoxy resin, wherein the mass ratio of the bisphenol A type epoxy resin to the phenolic epoxy resin is 1:1 to 4, for example, 1:1, 1:2, 1:3, or 1:4.

[0040] Preferably, the active diluent is p-tert-butylphenyl glycidyl ether and / or 1,6-hexanediol diglycidyl ether.

[0041] Preferably, the glass fibers used in the non-woven and alkali-free glass cloth have a specification of 90-275g / 1000m, a diameter of 6-13μm, and a glass fiber density of 2-4 fibers / mm.

[0042] Preferably, the epoxy resin-impregnated non-woven alkali-free glass cloth is dried and cured in a drying oven at a temperature range of 50°C to 120°C.

[0043] This invention involves impregnating electrical non-woven glass fiber cloth in a heated epoxy resin solution containing a high-boiling-point active diluent and conductive particles. The curing degree of the semiconductor adhesive on the substrate is controlled by adjusting the curing temperature and time, so that the adhesive is cured to stage B. After the base material is cooled and rolled up, a high-strength semi-cured glass cloth binding tape is obtained.

[0044] Preferably, the semi-cured glass cloth binding tape is prepared by the following method:

[0045] (1) Prepare epoxy resin solution;

[0046] (2) Impregnate the non-woven, alkali-free glass cloth in the epoxy resin solution of step (1);

[0047] (3) Dry and cure the non-woven alkali-free glass cloth impregnated with epoxy resin solution in a drying oven with a temperature range of 50℃~120℃ until the epoxy resin solution is cured to stage B.

[0048] (4) Cool the non-woven, alkali-free glass cloth that came out of the drying oven in step (3) to room temperature within 30 to 60 seconds, and then store it at 5°C to 10°C after winding it up.

[0049] The present invention also provides the application of the semi-cured glass cloth binding tape in motors or transformers.

[0050] The semi-cured glass cloth binding tape of the present invention is soft and easy to use. After binding, it can form a high-strength and tough binding through further heat curing. Especially after multi-layer wrapping and curing, the strength is significantly improved compared with the binding tape coated with curing resin.

[0051] The semi-cured glass cloth binding tape of the present invention is conductive. In the application of high-voltage motors and high-voltage transformers, it ensures that the binding tape and the iron core of the transformer being bound are at the same potential, which can effectively play a corona prevention role. It prevents partial discharge from the sharp corners of the glass cloth binding tape and the air gaps between the layers, which would cause resin aging and glass cloth embrittlement. It effectively avoids the reduction of binding strength and ensures the long service life of high-voltage motors and high-voltage transformers.

[0052] Compared to traditional soft cotton cloth and conventional glass cloth binding tape, the semi-cured glass cloth binding tape of the present invention has higher strength, which can effectively reduce the amount of material used and the cost in applications that require high-strength multi-layer binding.

[0053] The semi-cured glass cloth binding tape of this invention avoids the use of large amounts of organic solvents in the production and application process, greatly reducing the harm to the environment and production operators.

[0054] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0055] The semi-cured glass cloth binding tape provided by this invention has higher strength, anti-corona properties, and a longer service life when used in high-voltage motors and high-voltage transformers. The semi-cured glass cloth binding tape of this invention does not require the use of a large amount of organic solvents, making it more environmentally friendly and safer. Detailed Implementation

[0056] The technical solution of the present invention is further described below with reference to specific implementation examples, but the present invention is not limited to the following embodiments. The implementation conditions used in the embodiments can be further adjusted according to specific requirements, and the implementation conditions not specified are usually the conditions in conventional experiments.

[0057] Unless otherwise specified, all raw materials used in this invention are commercially available products.

[0058] Example 1

[0059] This embodiment provides a high-strength semi-cured glass cloth binding tape, which is prepared through the following steps:

[0060] (1) Preparation of epoxy resin solution:

[0061] In a special high-shear mixer with a scraper, 40 kg of liquid 127 epoxy resin and 20 kg of phenolic epoxy resin NPPL630L were first added to the mixer, which was equipped with a constant-temperature circulating water system. The mixer was started and stirred at 600 RPM for about 15 minutes at a constant temperature of 40°C until the epoxy resin was completely mixed and dissolved. 8 kg of mica powder with a particle size of about 10 μm and 2 kg of fumed silica Aerosil R202 particles were then slowly added to the epoxy resin in sequence, with the stirring speed controlled at 600 RPM during the addition process. After all the powders were added to the resin, the stirring and shear rate were increased to 1400 RPM and stirring was continued for about 0.5 hours until the semi-conductive particles were uniformly dispersed in the liquid epoxy resin. 5 kg of toughening agent ETBN, 7 kg of curing agent boron trifluoride dimethyl octylamine complex, 1 kg of carbon black (a mixture of nano-grade acetylene and furnace-processed carbon black, with a particle size range of 20–100 nm), and 2 kg of graphite were sequentially added to 15 kg of p-tert-butylphenyl glycidyl ether. The mixture was stirred until the curing agent, carbon black, and graphite were completely and evenly dispersed. Then, the mixture was added to the above-mentioned epoxy resin and powder mixture. The mixture was stirred at a stirring and shear rate of 1400 RPM for about 45 minutes until it was evenly mixed to obtain an epoxy resin solution.

[0062] (2) 150 alkali-free glass fibers with a weight of 134g / 1000m and a diameter of 9μm are warped into a non-woven alkali-free glass cloth with a density of 3 fibers / mm and a width of about 50mm. Then, the cloth is immersed in a glue tank containing the epoxy resin solution prepared above. The temperature in the glue tank is set to 40℃ to heat and reduce the viscosity of the epoxy resin solution, so as to better wet the non-woven alkali-free glass cloth. At the same time, the mixture is stirred continuously with a stirrer to make the epoxy resin solution in the tank uniform and free of sediment.

[0063] (3) After being impregnated, the non-woven and alkali-free glass cloth is squeezed back into the tank by double-ply plates with a fixed spacing. The cloth belt enters the vertical drying oven with a temperature distribution of 80℃~150℃ at a speed of 5m / min through rollers to cure the epoxy resin to stage B. The semi-cured binding tape is cooled to near room temperature within 60s by water-cooled air in the cooling box and then rolled into a 200-meter finished roll with a width of 50mm. It is then placed in a cold storage at a temperature of 5℃ for later use.

[0064] Example 2

[0065] This embodiment provides a high-strength semi-cured glass cloth binding tape, which is prepared through the following steps:

[0066] (1) Preparation of epoxy resin solution:

[0067] In a special high-shear mixer with a scraper, 35 kg of liquid 127 epoxy resin and 25 kg of phenolic epoxy resin NPPL630L were first added to the mixer, which was equipped with a constant-temperature circulating water system. The mixer was started and stirred at 600 RPM for about 15 minutes at a constant temperature of 40°C until the epoxy resin was completely mixed and dissolved. Then, 7 kg of mica powder with a particle size of about 10 μm and 2 kg of fumed silica Aerosil R202 particles were slowly added to the epoxy resin in sequence, while the stirring speed was controlled at 600 RPM during the addition process. After all the powders were added to the resin, the stirring and shear rate were increased to 1400 RPM and stirring was continued for about 0.5 hours until the semi-conductive particles were uniformly dispersed in the liquid epoxy resin. 5 kg of toughening agent ETBN, 7 kg of curing agent boron trifluoride dimethyl octylamine complex, 1 kg of carbon black (a mixture of nano-grade acetylene and furnace-processed carbon black, with a particle size range of 20–100 nm), and 3 kg of graphite were sequentially added to 15 kg of p-tert-butylphenyl glycidyl ether. The mixture was stirred until the curing agent, carbon black, and graphite were completely and evenly dispersed. Then, the mixture was added to the above-mentioned epoxy resin and powder mixture. The mixture was stirred at a stirring and shear rate of 1400 RPM for about 45 minutes until it was evenly mixed to obtain an epoxy resin solution.

[0068] (2) 150 alkali-free glass fibers with a weight of 198g / 1000m and a diameter of 11μm are warped into a non-woven alkali-free glass cloth with a density of 3 fibers / mm and a width of about 50mm. Then, the cloth is immersed in a glue tank containing the epoxy resin solution prepared above. The temperature in the glue tank is set to 40℃ to heat and reduce the viscosity of the epoxy resin solution, so as to better wet the non-woven alkali-free glass cloth. At the same time, the mixture is stirred continuously with a stirrer to make the epoxy resin solution in the tank uniform and free of sediment.

[0069] (3) After being impregnated, the non-woven and alkali-free glass cloth is squeezed back into the tank by double-ply plates with a fixed spacing. The cloth belt enters the vertical drying oven with a temperature distribution of 80℃~150℃ at a speed of 5m / min through rollers to cure the epoxy resin to stage B. The semi-cured binding tape is cooled to near room temperature within 60s by water-cooled air in the cooling box and then rolled into a 200-meter finished roll with a width of 50mm. It is then placed in a cold storage at a temperature of 5℃ for later use.

[0070] Comparative Example 1

[0071] This comparative example provides a fully cured glass cloth binding tape (using the adhesive formula of patent CN1034377A, and the glass fibers used in the non-woven and alkali-free glass cloth are the same as those in Example 1).

[0072] (1) Preparation of adhesive solution:

[0073] In a special high-shear mixer with a scraper, 75 kg of E42 (NPEL134) epoxy resin, 25 kg of E12 (NPES304) epoxy resin, 5 kg of plasticizer dibutyl phthalate, and 60 kg of solvent acetone are slowly added to the mixer in sequence. The stirring speed is controlled at 600 RPM. After stirring for about 1 hour, when the epoxy resin is completely dissolved and a homogeneous solution is formed, 8 kg of curing agent amine borane compound is added to the mixture. The mixture is then stirred for about 30 minutes to make it uniform.

[0074] (2) 150 alkali-free glass fibers with a weight of 134g / 1000m and a diameter of 9um are warped into a non-woven alkali-free glass cloth with a density of 3 fibers / mm and a width of about 50mm by a warping device and then immersed in a tank containing the above-prepared adhesive solution to allow the adhesive solution to completely impregnate the non-woven alkali-free glass cloth.

[0075] (3) After being impregnated, the non-woven and alkali-free glass cloth is squeezed back into the tank by double-ply plates with a fixed spacing. The cloth belt enters the vertical drying oven with a temperature distribution of 80℃~150℃ at a speed of 5m / min through rollers to completely cure the adhesive. The binding tape is then cooled to near room temperature by water-cooled air in a cooling box and then rolled into a 200-meter-long finished roll with a width of 50mm. It is then placed in a room temperature storage warehouse for later use.

[0076] The main properties of the semi-cured glass cloth binding tape of Examples 1 and 2 and the fully cured glass cloth binding tape of Comparative Example 1 were tested, and the results are shown in Table 1:

[0077] Table 1

[0078]

[0079] Note: Stiffness was tested according to the IEC 60371-2 mica tape stiffness test method; tensile strength was tested according to the IEC 60394-2 method; surface resistivity was tested according to the ASTM D 257 method.

[0080] Tensile strength test after curing of 3-layer sample: Take three 50mm wide and 200mm long sample segments, stack them together, put them into a pressure mold, set the pressure to 50N, put the entire mold into a 150℃ oven for curing for 15 minutes, take out the sample and cool it, and then perform tensile strength test according to IEC 60394-2.

[0081] As shown in Table 1, the semi-cured glass cloth binding tape provided by this invention has higher flexibility, higher strength, and conductivity during use, effectively preventing corona discharge and avoiding resin aging and glass cloth embrittlement caused by local discharge at the sharp corners and interlayer gaps of the glass cloth binding tape, thus ensuring the long service life of high-voltage motors and high-voltage transformers. Furthermore, the semi-cured glass cloth binding tape of this invention does not involve large amounts of organic solvents in its preparation and use, making it more environmentally friendly.

[0082] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A semi-cured glass cloth binding strap, characterized in that, It is formed by curing non-woven, alkali-free glass cloth impregnated with epoxy resin solution to stage B, followed by cooling and winding. The epoxy resin solution, based on 100% by weight, consists of the following components: Liquid epoxy resin 55%~60%; Toughening agent 4%~6%; Mica powder 6%~10%; Fumed silica 1%~3%; Hardener 8%~10%; Carbon black 0.5%~1%; Graphite 1%~3%; 10%~15% reactive diluent The liquid epoxy resin is a composition of bisphenol A type epoxy resin and phenolic epoxy resin, wherein the mass ratio of the bisphenol A type epoxy resin to the phenolic epoxy resin is 1:1~2. The toughening agent is a liquid rubber copolymer. The curing agent is a boron trifluoride dimethyl octylamine complex. The active diluent is glycidyl ether.

2. The semi-cured glass cloth binding tape according to claim 1, characterized in that, The particle size of the mica powder is 5~20μm; And / or, the carbon black is a mixture of nano-sized acetylene and furnace-processed carbon black; And / or, the particle size of the graphite is 20~100nm.

3. The semi-cured glass cloth binding tape according to claim 1, characterized in that, The active diluent is p-tert-butylphenyl glycidyl ether and / or 1,6-hexanediol diglycidyl ether.

4. The semi-cured glass cloth binding tape according to claim 1, characterized in that, The glass fibers used in the non-woven, alkali-free glass cloth have a specification of 90~275g / 1000m, a diameter of 6~13μm, and a glass fiber density of 2~4 fibers / mm.

5. The semi-cured glass cloth binding tape according to claim 1, characterized in that, The epoxy resin-impregnated non-woven alkali-free glass cloth is dried and cured in a drying oven at a temperature range of 50℃ to 120℃.

6. The semi-cured glass cloth binding tape according to claim 1, characterized in that, It is prepared using the following method: (1) Prepare epoxy resin solution; (2) Impregnate the non-woven, alkali-free glass cloth in the epoxy resin solution of step (1); (3) Dry and cure the non-woven, alkali-free glass cloth impregnated with epoxy resin solution in a drying oven with a temperature range of 50℃~120℃ until the epoxy resin solution is cured to stage B. (4) Cool the non-woven, alkali-free glass cloth that came out of the drying oven in step (3) to room temperature within 30~60 seconds, and then store it at 5℃~10℃ after winding it up.

7. The application of the semi-cured glass cloth binding tape as described in any one of claims 1 to 6 in motors or transformers.

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