JPH0418448B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention relates to a method for manufacturing an insulated coil using a novel low-viscosity impregnated resin. More specifically, the present invention relates to a method of manufacturing an insulated coil suitable for use in rotating machines that use high voltage, such as turbine generators and water turbine generators. [Prior art] In turbine generators, water turbine generators, etc.
As the demand for electricity increases, there is a growing trend to increase the capacity of individual units and raise the voltage used, and recently the voltage has increased to 30 kV.
Even products with high operating voltages reaching up to 100% have appeared. Due to this increase in working voltage, insulated coils are required to have stricter performance in many respects, such as heat cycle resistance against repeated starting and stopping, heat deterioration resistance due to temperature rise, and mechanical properties against vibrations and short circuits. It is becoming more and more common. Insulated coils built into rotating machines are generally placed in a gas phase, but under high voltage, corona discharge occurs due to air breakdown of the gas present in the coil, and the insulating layer of the coil is destroyed. Since ancient times, it has been used as an insulating material for heat resistance, corona resistance,
Insulating sheets (including tape-shaped ones, hereinafter the same) are used that use mica foil, which has excellent voltage resistance. A normal insulated coil is made by winding the above-mentioned insulating sheet around a coil conductor formed into a predetermined shape, and impregnating this wound layer with epoxy-impregnated resin to form an insulating layer. Many resins have high viscosity at room temperature and have short pot lives. Adding diluents is a common method for lowering the viscosity of resins, but regular diluents are highly irritating to the skin and often cause a drastic drop in properties, making it impossible to obtain sufficient properties. There is a drawback. [Summary of the Invention] As a result of extensive research to overcome the above-mentioned drawbacks, the present inventors have developed a mixture of 100% by weight of an epoxy compound containing at least two epoxy groups in the molecule and a curing agent for this epoxy compound. (hereinafter simply referred to as parts), by blending 5 to 300 parts of a polyfunctional vinyl monomer having two or more acrylic groups, methacrylic groups, or allyl groups in one molecule and 0.1 to 10 parts of a phenoxy resin. In addition to obtaining a new low-viscosity impregnating resin with a long pot life, this low-viscosity impregnating resin allows sufficient room-temperature impregnation without any impregnation defects, resulting in a low initial breakdown voltage. The present inventors have discovered that the electrical characteristics are extremely stable after thermal deterioration, leading to the completion of the present invention. That is, the present invention provides an insulated coil having an insulating layer in which an insulating sheet with a porous insulating material as a backing material is wound around a coil conductor, and this wound layer is impregnated with a low-viscosity impregnated resin and then formed under heat and pressure. In the manufacturing method, the low-viscosity impregnating resin is a mixture of an epoxy compound containing at least two epoxy groups in one molecule and a curing agent for this epoxy compound.
A low viscosity product produced by blending 5 to 300 parts by weight of a polyfunctional vinyl monomer having two or more acrylic groups, methacrylic groups, or allyl groups in one molecule and 0.1 to 10 parts by weight of a phenoxy resin based on the weight part. This is a method for manufacturing an insulated coil characterized by using an impregnated resin. The present invention is characterized by blending low-viscosity acrylic (methacrylic) or allyl monomer with the epoxy compound to lower the viscosity of the impregnating resin, and also by making the epoxy cured network and vinyl crosslinked network compatible, which do not react with each other. By uniformizing the resin well, it is possible to achieve both the flexibility and dimensional stability of the epoxy resin and the effect of increasing the heat distortion temperature of the vinyl resin, thereby producing a well-balanced cured product. Furthermore, by adding phenoxy resin as a high molecular weight component, flexibility can be imparted to the impregnated resin by interposing the phenoxy resin as a non-crosslinking linear component in the crosslinked network. This is also one of the features of the present invention. Hereinafter, a method for manufacturing an insulated coil according to the present invention will be explained. First, the epoxy compound that can be used in the present invention may be any compound having at least two epoxy groups in one molecule, such as bisphenol A type DER-332 (trade name of Dow Corporation),
Novolac type DEN- such as Epicote 828 (Ciel company product name), GY-255 (Ciba company product name)
431 (trade name of Dow Corporation), alicyclic type CY-179 (trade name of Ciba Corporation), and these can be used alone or in combination. Furthermore, the epoxy curing agent that can be used in the present invention may be any cyclic acid anhydride, such as methyltetrahydrophthalic anhydride [HN-
2200 (Hitachi Chemical brand name)], Methylhexahydrophthalic anhydride [HN-5500 (Hitachi Chemical brand name)],
Examples include methyl highmic acid anhydride (trade name of Hitachi Chemical). Further, as curing accelerators, metal salts such as tricresyl borate, triethanolamine titanate, cobalt acetylacetonate, zinc octylate, metal chelate compounds, BF ₃ , BCl ₃ , PF ₃ ,
Lewis acids such as AsF ₅ and their amine complexes can be used, and these may be mixed and used if necessary. Further, examples of the polyfunctional vinyl monomer having an acrylic (methacrylic) group or allyl group in one molecule that can be used in the present invention include diallyl phthalate, diallyl isophthalate, triallyl trimellitate, triallyl isocyanurate,
Examples include bisphenol A diglycidyl ether di(meth)acrylate, trimethylolpropane tri(meth)acrylate, and trihydroxyethyl isocyanurate tri(meth)acrylate. Epoxy compound curing agent is an epoxy compound
It is desirable to mix it in a ratio of 50 to 150 parts per 100 parts. If the blending amount is out of this range, the cross-linking between the epoxy component and the curing agent component will not be sufficient, and the heat distortion temperature and mechanical and electrical properties will decrease, both of which are unfavorable. A polyfunctional vinyl monomer having an acrylic (methacrylic) group or an allyl group in one molecule is a mixture of an epoxy compound and a curing agent.
It is desirable to mix in the range of 5 to 300 parts. If the blending amount is less than 5 parts, the effect of adding the vinyl compound (lower viscosity, etc.) cannot be obtained, and if it exceeds 300 parts, the curing shrinkage rate becomes too large and the properties as an impregnated resin deteriorate, which are both undesirable. In addition, the phenoxy resin has a molecular weight of 15,000 to 6,000 per 100 parts of the epoxy compound.
It is desirable to use 10 parts. If the amount is less than 0.1 part, the effect of imparting flexibility will not be sufficient, and if it exceeds 10 parts, the viscosity of the impregnated resin will increase too much, which is not preferred in practice. Furthermore, for the purpose of promoting the reaction of the impregnated resin used in the present invention, it is effective to add a catalyst. Examples of this catalyst include vinyl polymerization initiation catalysts such as dicumyl peroxide, benzoyl peroxide, di-t-butyl hydroperoxide, and azobisisobutyronitrile. In order to further reduce the viscosity of this impregnated resin, a monofunctional vinyl monomer such as styrene, vinyltoluene, α-methylstyrene, acrylonitrile, N-vinylpyrrolidone, etc. is added to the impregnated resin.
Although it is possible to add up to 200 parts per part, it is necessary to keep the amount to the minimum necessary since this will lead to deterioration of various properties. The insulated coil of the present invention is produced by winding an insulating sheet around a coil conductor, impregnating this wound layer with the above-mentioned novel low-viscosity impregnated resin under vacuum and pressure under known conditions, and then inserting it into a mold and forming it under heat and pressure. At the very least, an insulated coil is manufactured. The heating and pressing conditions are a heating temperature of 100 to 250°C, a pressure of 5 to 100 Kg/cm ² , and a heating time of 4 to 24 hours, thereby obtaining an insulated coil with excellent electrical and thermal properties. . If the molding conditions are outside the above range, the interlayer adhesion of the obtained insulated coil will be weak, resulting in a marked decrease in electrical properties during thermal deterioration, and undesirable floating or peeling of the insulating layer. As described above, according to the present invention, it is possible to manufacture an insulated coil that has excellent electrical characteristics, particularly dielectric loss tangent-voltage characteristics (hereinafter simply referred to as Δtanδ) after thermal deterioration, compared to insulated coils formed using conventional epoxy-impregnated resin. became possible. [Examples of the Invention] The method for manufacturing an insulated coil of the present invention will be described in detail below with reference to Examples and Comparative Examples. Example 1 As an epoxy compound, 80 parts of Epicote 828 (product name of Ciel Corporation), 65 parts of HN-2200 (product name of Hitachi Chemical), 20 parts of trimethylolpropane triacrylate, and 0.2 parts of a phenoxy resin with a molecular weight of about 30,000 were added.
part, 0.05 part of dicumyl peroxide as a catalyst,
0.2 parts of zinc octylate was added to obtain a low viscosity impregnated resin. The initial viscosity of this impregnated resin was 100 cps (centipoise) at 25°C. Next, glass cloth (manufactured by Arisawa Seisakusho, thickness 0.025 mm) was placed on the coil conductor with a cross section of 40 x 10 mm, which was made by combining 2 x 5 x 2000 mm double glass-wound rectangular copper wires in 2 rows and 20 stages. The laminated mica tape obtained as a material is wound 12 times in a half-overlapping manner, and Tetron tape (manufactured by Teijin, thickness 0.125 mm) is added as a protective layer.
was wound once, vacuum impregnated with the low viscosity impregnating resin obtained above for 1 hour at a pressure of 0.1 mmHg or less, then pressure impregnated for 4 hours at a pressure of 3 kg/ ^cm2 , and then inserted into a mold. 6 at temperature 135℃ and pressure 20Kg/ ^cm2
After heating and pressure molding for a period of time, the temperature is further increased to 150°C.
Polymerization was carried out for 16 hours to obtain an insulated coil. In order to investigate the characteristics of this insulated coil, we investigated the initial Δtanδ and breakdown voltage, and the Δtanδ after 16 days at 180℃.
were measured respectively. These results are shown in Table 1. The pot life (pot life) of the above low viscosity impregnated resin is determined when the resin is heated at a temperature of 25°C and a relative humidity of 35%.
The sample was placed in a constant temperature and humidity chamber, and the viscosity was monitored periodically. That is, in this measurement, the number of days until the viscosity at 25°C reached 400 cps was defined as the pot life. If the viscosity is higher than 400 cps, it becomes difficult to completely impregnate the insulated coil, which is not preferable. As a result, the viscosity of the above-mentioned impregnated resin did not exceed 400 cps even after 6 months at 25°C, and was very good. Next, this low viscosity impregnated resin was cured at 110°C for 6 hours and then further at 150°C for 16 hours to obtain a cured product. The bending strength of this cured product was measured based on JIS K7203. As a result, a result of 12 Kg/mm ² at 25°C was obtained, which was very good. In addition, weight loss on heating was measured based on JIS C2103. the result,
The weight loss after heating at 180°C for 16 days was 2.0%, which was a good value. The results of the above initial viscosity, pot life bending strength, heating weight loss are summarized in Table 2. Example 2 HN-5500 (Hitachi Chemical brand name) was added to 100 parts of GY-255 (Ciba brand name) as an epoxy compound.
86 parts, trihydroxyethyl isocyanurate 30
0.3 parts of phenoxy resin with a molecular weight of about 30,000, 10 parts of styrene, and 0.2 parts of benzoyl peroxide and 0.5 parts of cobalt acetylacetonate as catalysts.
was added to obtain a low viscosity impregnated resin. The initial viscosity of this impregnated resin was 80 cps at 25°C. Next, an insulated coil was manufactured under the same conditions as in Example 1, and the Δtanδ and initial breakdown voltage were measured, and as in Example 1, they were very good.
These results are shown in Table 1. In addition, the pot life of the above impregnated resin is 6 at 25℃.
Even after several months, the level remained very good and did not exceed 400 cps. Furthermore, good values of 12 Kg/mm ² and 1.7% were obtained for bending strength and weight loss after heating at 200° C. for 16 days, respectively. These results are shown in Table 2. Example 3 As an epoxy compound, 2.0 parts of phenoxy resin with a molecular weight of about 30,000, 92 parts of methyl hymite anhydride (trade name of Hitachi Chemical), and trimethylolpropane triacrylate were added to 100 parts of GY-255 (trade name of Ciba Corporation). A low viscosity impregnated resin was produced in the same manner as in Example 1, except that 10 parts of trihydroxyethyl isocyanurate trimethacrylate, 0.2 parts of di-t-butyl hydroperoxide and 0.3 parts of zinc octylate were added as catalysts. . The initial viscosity of this impregnated resin was 100 cps at 25°C. Furthermore, an insulated coil was manufactured in the same manner as in Example 1,
When Δtanδ and initial breakdown voltage were measured, they were very good as in Example 1. These results are shown in Table 1. In addition, the pot life of the above impregnated resin is 6 at 25℃.
Even after several months, the level remained very good and did not exceed 400 cps. These results are shown in Table 2. Example 4 As epoxy compounds, 100 parts of DER-332 (trade name of Dow Corporation) and 10 parts of Epicote 1004 (trade name of Ciel Corporation) were used.
0.2 parts of phenoxy resin with a molecular weight of approximately 30,000
parts, trihydroxyethyl isocyanurate triacrylate 40 parts, styrene 10 parts, HN-2200
A low-viscosity impregnated resin was produced in the same manner as in Example 1, except that 85 parts of (Hitachi Chemical brand name) were added, and 0.1 part of dicumyl peroxide and 0.2 parts of zinc octylate were added as catalysts. The initial viscosity of this impregnated resin is 25℃
It was 120cps. Furthermore, an insulated coil was manufactured in the same manner as in Example 1,
When Δtanδ and initial breakdown voltage were measured, they were very good as in Example 1. These results are shown in Table 1. In addition, the pot life of the above impregnated resin is 6 at 25℃.
Even after several months, the level remained very good without exceeding 400 cps. These results are shown in Table 2. Comparative Example 1 15 parts of phenoxy resin with a molecular weight of about 30,000, 80 parts of HN-2200 (Hitachi Chemical product name), and 350 parts of trihydroxyethyl isocyanurate triacrylate to 100 parts of GY-255 (product name of Ciba Corporation) as an epoxy compound. A low-viscosity impregnated resin was produced in the same manner as in Example 1, except that 100 parts of styrene, 0.2 parts of dicumyl peroxide, and 0.3 parts of zinc octylate were added as catalysts. When we measured the properties of this impregnated resin and the properties of the insulated coil, we found that the initial viscosity of the impregnated resin was 25°C.
Although it was a reasonable 150 cps, it exceeded the usage range of the phenoxy resin used for the impregnating resin, so the pot life characteristics were very poor (over 400 cps after 30 days). Furthermore, since the polyfunctional vinyl monomer exceeds the usable range in terms of curing properties and properties of the insulated coil, the bending strength, weight loss upon heating, and electrical properties of the insulated coil were extremely poor. These results are also shown in Tables 1 and 2. Comparative Example 2 HN-2200 (Hitachi Chemical brand name) was added to 100 parts of GY-255 (Ciba brand name) as an epoxy compound.
A low-viscosity impregnated resin was produced in the same manner as in Example 1, except that 85 parts of 2-ethyl, 4-methylimidazole (trade name of Shikoku Kasei) was added as a catalyst. When we measured the properties of this impregnated resin and the properties of the insulated coil, we found that the initial viscosity was already 650 cps at 25°C.
Therefore, it was unsuitable as a room temperature impregnation resin. Furthermore, in the manufacturing process of insulated coils, the initial viscosity was high, resulting in poor impregnation and very poor electrical properties. These results are also shown in Tables 1 and 2.

【table】

[Table] Measured in oil at constant pressure increase rate

〔Effect of the invention〕

As described above, the insulated coil according to the present invention uses a novel low-viscosity impregnated resin to provide electrical and
It has extremely excellent properties, particularly both dielectric loss tangent-voltage properties (Δtanδ) and thermal properties after thermal deterioration, and is excellent in suitability for high-voltage rotating machines, making it extremely important in industrial applications.

Claims (1)

[Claims] 1. An insulation having an insulating layer formed by winding an insulating sheet with a porous insulating material as a backing material around a coil conductor, impregnating the wound layer with a low-viscosity impregnated resin, and molding the resultant under heat and pressure. In the coil manufacturing method, for 100 parts by weight of a mixture of an epoxy compound containing at least two epoxy groups in one molecule and a curing agent for this epoxy compound as the low-viscosity impregnating resin, two epoxy groups in one molecule are added. Polyfunctional vinyl monomer 5 having the above acrylic group, methacrylic group, or allyl group
A method for producing an insulated coil, characterized by using a low-viscosity impregnating resin produced by blending ~300 parts by weight and 0.1 to 10 parts by weight of a phenoxy resin. 2 The low viscosity impregnating resin is added to 100 parts by weight of the mixture of the epoxy compound and the curing agent for the epoxy compound,
2. The method for producing an insulated coil according to claim 1, wherein the vinyl monomer having one vinyl group per molecule is blended in an amount not exceeding 200 parts by weight. 3 As a phenoxy resin, the molecular weight is 15,000~
The method for manufacturing an insulated coil according to claim 1, using a phenoxy resin in the range of 60,000. 4 The heating and pressure molding conditions are heating temperature 100-250℃,
The method for manufacturing an insulated coil according to claim 1 or 3, wherein the applied pressure is 5 to 100 Kg/cm ² and the heating time is 4 to 24 hours.