JP6430319B2 - Electrical insulating paper and static induction machine using the same - Google Patents

Description

  The present invention relates to an electrical insulating paper, and more particularly to an electrical insulating paper used in a state immersed in an electrical insulating oil and a static induction electric machine using the electrical insulating paper.

  An oil-filled transformer is one type of static induction electrical equipment. An oil-filled transformer has an iron core and a winding attached to the iron core immersed in the electric insulating oil in the tank. Electrical insulation paper (simply insulated) is used as the insulation for the winding conductor. (Also called paper). Insulating paper is a mat-like material having fine voids, and it is known that the insulating paper exhibits excellent insulating properties when the voids are impregnated with an electric insulating oil (also simply referred to as insulating oil). Oil-filled transformers are widely used as transformers connected to electrical systems.

  Insulating oil is classified according to its main component, and as the main component, for example, mineral oil, alkylbenzene, polybutene, alkylnaphthalene, silicone oil, and ester oil are used. Insulating paper includes kraft paper, cellulose dielectric paper, chemical-added paper, synthetic fiber paper, etc., but paper based on kraft paper is currently used for comprehensive convenience including cost and characteristics. But it is mainstream. In this specification, the insulating paper includes a press board.

  Reliability and durability (long-term reliability) are very important for transformers connected to the power system. The deterioration of the oil-filled transformer is caused by the aging deterioration of the insulating oil and the insulating paper, and oxygen and water are mainly involved in the deterioration of the insulating oil and the insulating paper.

  When the insulating oil deteriorates, the performance of the insulating oil can be recovered by performing a degassing filtration process or a new oil replacement. On the other hand, when the insulating paper deteriorates, it is practically extremely difficult to replace the insulating paper. Therefore, it is said that the life of the oil-filled transformer is substantially determined by the deterioration of the insulating paper.

  Insulating paper (other than synthetic fiber paper) widely used in oil-filled transformers, etc. is mainly composed of cellulose, and the average degree of polymerization of cellulose (average number of glucose rings in cellulose) is an indicator of deterioration of insulating paper. It is used as. The use limit (life) of such insulating paper is about 450 in terms of the average degree of polymerization of cellulose, according to the Japan Electrical Manufacturers' Association (JEM standard, published in 1993).

  Here, the decomposition reaction of cellulose, which is the main component of the insulating paper, will be briefly described. Cellulose is a polymer material in which glucose rings are polymerized in a chain as shown in Chemical Formula 1 below.

The decomposition reaction of cellulose ((C ₆ H ₁₀ O ₅ ) _n ) is roughly classified into three types: an oxidation reaction, a hydrolysis reaction, and a thermal decomposition reaction. In the oxidation reaction, hydroxyl groups (-OH) in cellulose are oxidized into carbonyl groups (-CO-) and carboxyl groups (-COOH) in the presence of oxygen, and water (H ₂ O), carbon dioxide (CO ₂ ) And carbon monoxide (CO). The hydrolysis reaction is a reaction in which an ether bond (—O—) in cellulose in the presence of water is cleaved to generate carbon dioxide, carbon monoxide, glucose molecules (C ₆ H ₁₀ O ₆ ), and the like. The thermal decomposition reaction is a reaction in which chemical bonds in cellulose are broken by heat.

  Since the thermal decomposition reaction requires a higher temperature than the oxidation reaction and the hydrolysis reaction, it is less likely to occur in the normal environment than the oxidation reaction and the hydrolysis reaction. Since the hydrolysis reaction cuts the main chain of cellulose, the average polymerization degree of cellulose is directly reduced. Moreover, it is said that the carboxyl group produced | generated by oxidation reaction shows a catalytic action with respect to a hydrolysis reaction. Further, when a carboxyl group is generated, decomposition of the cellulose proceeds in a chain, and water and a carboxyl group are generated. From these facts, it is considered that the durability of the insulating paper is enhanced by suppressing the generation of carboxyl groups by the oxidation reaction and the chain decomposition reaction.

  Various techniques for improving the heat resistance of cellulose have been proposed. For example, there are a method of cyanoethylating cellulose with acetonitrile and a method of acetylating cellulose. However, since the hydroxyl group of cellulose forms hydrogen bonds between molecules, the chemical reactivity is low, and the above method requires a complicated manufacturing process, and the cost is increased accordingly. Therefore, a method for improving the water resistance and heat resistance of cellulose without requiring a chemical reaction with a hydroxyl group of cellulose is required.

  As a general technique for suppressing a chain decomposition reaction by a carboxyl group, there is a technique using a phenol-based or aromatic amine-based antioxidant. These are said to capture peroxides, which are precursors of carboxyl groups, to stop chain reactions and prevent oxidation reactions. For example, Patent Document 1 (Japanese Patent Laid-Open No. 2006-278916) discloses an insulating paper that is immersed in an electrical insulating oil containing an amine compound and / or a phenol compound. According to Patent Document 1, by immersing the insulating paper in an electrical insulating oil containing an amine compound and / or a phenol compound, deterioration of the insulating paper is suppressed by the action of the amine compound and / or the phenol compound. It is said that.

  On the other hand, a method of covering the insulating paper with a phenolic or aromatic amine-based resin having an antioxidant effect is also conceivable. For example, Patent Document 2 (Japanese Patent Laid-Open No. 11-293586) discloses a gas insulating press board in which para-aromatic polyamide fibers and dry paper made of uncured phenol resin fibers are laminated. According to Patent Document 2, it is said that a highly heat-resistant press board can be obtained by using uncured phenol resin fibers as binder fibers for para-aromatic polyamide fibers.

JP 2006-278916 A JP 11-293586 A

  As described above, the life of the oil-filled transformer is said to largely depend on the life of the insulating paper. In general, when operating a transformer, it is considered that the temperature rise is greater with insulating paper coated directly on the winding conductors than with insulating oil. The allowable temperature depends greatly on the heat resistance of the insulating paper covering the winding conductor.

  In recent years, the demand for renewal of oil-filled transformers is increasing, and oil-filled transformers with high efficiency, large capacity, and / or downsizing are strongly desired for renewal. One solution that satisfies these requirements is downsizing by increasing the operating temperature of the oil-filled transformer.

  On the other hand, since the cellulose decomposition reaction described above is a kind of chemical reaction, the reaction rate increases as the temperature rises. In other words, in order to satisfy the requirements for oil-filled transformers, insulating paper that can suppress the decomposition reaction of cellulose even when the operating temperature rises (in other words, insulating paper with high heat resistance and durability) is required. ing. As mentioned above, insulating paper is a mat-like material with fine voids, and exhibits excellent insulating properties when the gap is impregnated with electrical insulating paper. It is necessary to combine sex.

  In addition, even if high-performance insulating paper is used, it is not suitable as an industrial product if the cost increases greatly. Providing insulating paper produced by a simple process at a low cost is one of the most important issues. is there.

  The insulating paper described in Patent Document 1 is expected to suppress the oxidative decomposition reaction of the insulating paper by being immersed in an electrical insulating oil containing an amine compound and / or a phenol compound. However, since the amount of electrical insulating oil is required to be several tens of times that of insulating paper, the method for suppressing deterioration of insulating paper disclosed in Patent Document 1 requires a large amount of amine-based compounds and / or phenol-based compounds. Leading up. Furthermore, as described in Patent Document 1, when a large amount of an amine compound and / or a phenol compound is contained, the performance of the insulating paper tends to be adversely affected. In addition, degradation products generated by degradation of amine compounds and / or phenolic compounds may accelerate the deterioration of insulating paper, so a large amount of amine compounds and / or phenolic compounds are contained. It is not preferable to do.

  In addition, phenolic compounds and aromatic amine compounds having an antioxidant effect have high lipophilicity and are more easily adapted to insulating oil than cellulose. Therefore, even if phenolic or aromatic amine compounds are added to insulating paper, the phenolic or amine compounds are eluted and liberated when immersed in electrical insulating oil, preventing oxidation of insulating paper. The effect is considered to be weak.

  On the other hand, since the press board described in Patent Document 2 is not an insulating paper based on cellulose in the first place, the mechanical properties, electrical insulating performance, and impregnation of insulating oil possessed by conventional insulating paper based on kraft paper It is considered to be different from gender. In addition, there is a concern about a significant cost increase compared to insulating paper based on kraft paper.

  Therefore, the object of the present invention is superior to the conventional one by suppressing the decomposition reaction of cellulose while maintaining the mechanical properties, electrical insulating performance and properties equivalent to the impregnation property of insulating oil, which the conventional electrical insulating paper has. The object is to provide an electrically insulating paper having heat resistance at low cost. Another object of the present invention is to provide a static induction device using the electrical insulating paper.

  In order to achieve the above object, another aspect of the present invention is an electrically insulating paper, which is a paper base material mainly composed of cellulose, an adsorption layer formed by adsorption on the surface of the paper base material, There is provided an electrical insulating paper characterized by having a phenol-based or amine-based compound chemically bonded to an adsorption layer.

  Another aspect of the present invention is a static induction electric machine having a structure in which an iron core and a conductor winding are combined and insulated with an electric insulating paper and an electric insulating oil, respectively, in order to achieve the above object. There is provided a static induction electric machine characterized in that the electric insulating paper is the electric insulating paper according to the present invention.

  According to the present invention, while maintaining the mechanical properties (for example, tensile strength), electrical insulation properties, and impregnation properties of insulating oils that conventional electrical insulating paper has, the cellulose decomposition reaction is suppressed and the conventional properties are suppressed. It is possible to provide an electrical insulating paper having durability and heat resistance superior to those at a low cost. In addition, by using the electrical insulating paper, it is possible to provide an oil-filled static induction appliance that can cope with high efficiency, large capacity, and / or downsizing.

It is a cross-sectional schematic diagram of the electrical insulating paper which concerns on this invention. It is a longitudinal cross-sectional schematic diagram which shows an example of the oil-filled transformer using the electrical insulation paper which concerns on this invention. It is a cross-sectional schematic diagram which shows an example of the insulated wire used for the oil-filled transformer which concerns on this invention.

  As described above, the electrical insulating paper according to the present invention is an electrical insulating paper, which is a paper base material mainly composed of cellulose, an adsorption layer formed by adsorption on the surface of the paper base material, and the adsorption layer. And a phenol-based or amine-based compound that is chemically bonded to the compound.

Further, the present invention can add the following improvements and changes to the above-mentioned electrical insulating paper.
(I) The adsorption layer is made of at least one of urea, thiourea, hexamethylenetetramine, melamine, dicyanciamide, and polyacrylamide.
(Ii) The chemical bond is an ether bond (—O—), an ester bond (—COO—), a carbonyl bond (—CO—), an amide bond (—CONH—), an imide bond (—CONHCO—), or an imine bond. (—C═N—) consisting of at least one (—COHCNH—) bond formed by an epoxy ring-opening reaction.
(Iii) The electrical insulating paper has a heat-resistant temperature index based on JEC standard 6151 of +18 K or more, and the amount of phenolic or amine compound containing the chemical bond is 1% by mass or less based on the paper substrate It is.

  Hereinafter, embodiments according to the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the embodiment taken up here, and can be appropriately combined and improved without departing from the technical idea of the present invention.

(Electrical insulating paper)
FIG. 1 is a schematic cross-sectional view of an electrical insulating paper according to the present invention. As shown in FIG. 1, the electrical insulating paper 10 according to the present invention has an adsorption layer 13 formed on the surface of a paper substrate 12 mainly composed of cellulose 11 and is chemically bonded to the outside of the adsorption layer 13. The phenolic or amine compound 15 is bonded through 14 to form the antioxidant layer 16.

  The electrical insulating paper 10 of the present invention is configured as described above, so that even if it is immersed in electrical insulating oil, the phenol-based or amine-based compound 15 does not elute and is released, The antioxidant effect of cellulose 11 can be maintained for a long time.

  On the other hand, the antioxidant layer 16 exhibits good lipophilicity with respect to the oil component due to the phenolic or amine compound 15. Further, since the adsorption layer 13 and the antioxidant layer 16 are thin, the structural characteristics of the cellulose 11 having fine voids are maintained, and the oil component quickly permeates between the celluloses 11 of the paper base 12. As a result, the electrical insulating paper 10 exhibits good insulating oil impregnation properties when immersed in the electrical insulating oil. As described above, the insulating oil impregnation property of the electrical insulating paper is one of the important characteristics from the viewpoint of electrical insulation and cooling performance in the oil-filled transformer.

  In the present invention, the adsorption layer 13 is preferably formed by adsorption on the paper substrate 12 by chemical adsorption (for example, hydrogen bonding or dipole interaction). In addition, the phenolic or amine compound 15 in the present invention is preferably firmly bonded to the adsorption layer 13 by some chemical bond 14. For example, ether bond (-O-), ester bond (-COO-), carbonyl bond (-CO-), amide bond (-CONH-), imide bond (-CONHCO-), imine bond (-C = N- ), (-COHCNH-) bond formed by epoxy ring-opening reaction. As a result, the bond between the paper substrate 12 and the adsorption layer 13 is strengthened, and the bond between the adsorption layer 13 and the antioxidant layer 16 is also strengthened. As a result, the phenol-based or amine-based compound 15 exhibits good oil resistance (not eluted or liberated from the paper substrate 12 even in electrical insulating oil). On the other hand, when the phenolic or amine compound 15 is adsorbed on the paper base 12 or the adsorption layer 13 without the chemical bond 14, it is eluted and released from the insulating paper in the electric insulating oil due to low oil resistance. Therefore, the antioxidant effect cannot be maintained for a long time.

  That is, the electrical insulating paper 10 of the present invention, in addition to the antioxidant effect of the paper substrate 12, is oleophilic which is familiar with the electrical insulating oil, oil resistance which is not eluted or released in the electrical insulating oil, and the electrical insulating oil quickly It is characterized in that it has the effect of impregnating the insulating oil to be permeated into the resin (details will be described later).

  An amine compound is preferably used as the adsorbing layer 13 that adsorbs and forms on the paper substrate 12. As the amine compound, at least one of urea, thiourea, hexamethylenetetramine, melamine, dicyanciamide, and polyacrylamide can be preferably used. Since these amine compounds are hydrophilic, they have a high affinity with cellulose and are easily chemically adsorbed to the paper substrate 12. Therefore, once adsorbed, it can remain on the surface of the paper base material 12 without being easily eluted and released from the insulating paper 12.

  In addition, when an amine compound encounters a water molecule, it can chemically react and consume the water molecule. Therefore, the adsorption layer 13 has an effect of consuming the water and suppressing hydrolysis of the cellulose 11.

  The above amine compound has good chemical reactivity with a certain kind of hydrophilic functional group. Therefore, the phenol-based or amine-based compound 15 has at least one of an aldehyde group (—CHO), a hydroxyl group (—OH), a carboxyl group (—COOH), and a glycidyl group (epoxy group) as a hydrophilic functional group at the terminal. It is preferable to have one. By having these hydrophilic functional groups, the amine compound (that is, the adsorption layer 13) and the phenol-based or amine-based compound 15 are easily chemically bonded.

  The phenol-based or amine-based compound 15 is not particularly limited except that it is bonded to the adsorption layer 13 through the chemical bond 14 and further has an antioxidant effect. For example, compounds containing phenols and hydrophilic functional groups such as 3,5-di-tert-butyl-4-hydroxybenzoic acid, and aromatic amines and hydrophilic functional groups such as N-phenylanthranilic acid A compound comprising is preferably selected.

  Further, the paper substrate 12 may contain a carboxylic acid removing agent. As the carboxylic acid removing agent, a compound containing a carbodiimide group (for example, N, N′-dicyclohexylcarbodiimide) can be preferably used. A compound containing a carbodiimide group can suppress hydrolysis of cellulose 11 by chemically reacting with carboxylic acid produced by oxidative degradation of cellulose 11 and consuming the carboxylic acid.

(Method for producing electrical insulating paper)
There is no particular limitation on the method of providing the adsorption layer 13 on the surface of the paper substrate 12 and the method of bonding the phenolic or amine compound 15 to the adsorption layer 13 via the chemical bond 14, and as a result, the adsorption layer 13 and The antioxidant layer 16 may be coated on the surface of the paper substrate 12. For example, the adsorption layer 13 is formed by applying a solution containing a predetermined amine compound to the surface of the paper substrate 12 by a conventional coating method (dip coating, spray coating, roll coating, etc.) and heating (so-called baking) ) Can be done. Similarly, the formation of the antioxidant layer 16 is performed by applying a solution containing a predetermined phenol-based or amine-based compound to the surface of the paper substrate 12 on which the adsorption layer 13 is formed by adsorption by a conventional coating method, It can be performed by heating (chemical bonding). That is, an electrical insulating paper having excellent durability and heat resistance can be obtained by a simple method (at low cost).

  In the production of the press board, the paper base material 12 on which the adsorption layer 13 and the antioxidant layer 16 are formed in advance may be laminated and pressed, or may be adsorbed on the board produced by lamination and pressing. Layer 13 and antioxidant layer 16 may be formed.

(Static induction machine)
In this embodiment, an oil-filled transformer will be described as an example of a static induction electric device. FIG. 2 is a schematic longitudinal sectional view showing an example of an oil-filled transformer using the electrical insulating paper according to the present invention. As shown in FIG. 2, the insulating support base 23a is placed on the lower support bracket 22 attached to the lower part of the iron core 21, and the inter-coil spacer 24a and the disk coil 25a are alternately stacked on the insulating support base 23a. Thus, the low voltage winding 26 is formed. An electrostatic shield 27a is placed on the top of the low-voltage winding 26. An insulating cylinder 29 is formed by applying a straight spacer 28 to the outside of the low-voltage winding 26 and winding an electrically insulating paper on the outside. A main insulating portion 210 is formed by disposing a similar straight spacer 28 and insulating cylinder 29 on the outside thereof.

  On the outside of the straight spacer 28 located on the outermost side of the main insulating part 210, the insulated wire is wound while being wound to form a disk coil 25b, and the disk coil 25b and the inter-coil spacer 24b are alternately stacked, A high voltage winding 211 is formed. An electrostatic shield 27b is provided on the uppermost portion of the high-voltage winding 211.

  The insulating support 23b is placed on the low-voltage winding 26 and the high-voltage winding 211 thus formed, and the upper support fitting 212 with the push bolt 213 mounted thereon is mounted on the iron core 31. A load is applied to the insulating support 23b with the push bolt 213, and the low-voltage winding 26 and the high-voltage winding 211 are tightened to constitute the winding body.

  A high voltage lead 214 is drawn from the upper end of the high voltage winding 211 and connected to the high voltage bushing 215. At this time, a support arm 216 having a hole into which the high-voltage lead wire 214 is inserted is taken out from the upper support fitting 212, and the high-voltage lead wire 214 is placed in this hole to support the middle of the high-voltage lead wire 214. In addition, a lead wire barrier 218 is disposed by winding an electrical insulating paper through a spacer 217 in a portion where the insulation distance from the periphery of the high voltage lead wire 214 is small. All of these are housed in a transformer body container 220 filled with electrical insulating oil 321 (for example, mineral oil) to constitute an oil-filled transformer.

  FIG. 3 is a schematic cross-sectional view showing an example of an insulated wire used in the oil-filled transformer according to the present invention. The insulated wire 30 includes a conductor 31 and an insulating coating 32 that covers the surface of the conductor 31. The insulating coating 32 is made of the electrical insulating paper 10 of the present invention.

  In the oil-filled transformer of the present invention, the above-described electrical insulating paper 10 of the present invention is used for the inter-coil spacers 24a and 24b, the straight spacer 28, and the insulating coating 32. By using electrical insulating paper with high durability and heat resistance, it is possible to increase the operating temperature of the oil-filled transformer. Thereby, it is possible to provide an oil-filled stationary induction device that is compatible with high efficiency, large capacity, and / or downsizing.

  Next, the present invention will be described more specifically with reference to examples and comparative examples. The present invention is not limited to these examples.

(Production of electrical insulating paper of Examples 1 to 12)
Kraft paper was prepared as the paper base 12. As amine compounds constituting the adsorption layer 13, urea, thiourea, hexamethylenetetramine, melamine, dicyandiamide, and polyacrylamide were prepared. The phenolic or amine compound constituting the antioxidant layer 16 is a phenolic or amine compound having a hydrophilic functional group as a carboxyl group (each compound name: 3,5-di-tert-butyl-4- Hydroxybenzoic acid and N-phenylanthranilic acid) were prepared.

  As the formation of the adsorption layer 13, first, urea, thiourea, hexamethylenetetramine, melamine, dicyandiamide, and polyacrylamide, which are amine compounds, were dissolved in a solvent (water or ethanol) to prepare a 1 mass% amine compound solution. Next, the kraft paper was immersed in the solution for 5 minutes, then taken out and dried to form the adsorption layer 13 on both sides of the kraft paper.

  In order to form the antioxidant layer 16, the above-mentioned phenol-based or amine-based compound 15 was dissolved in a solvent (acetone) to prepare a 1% by mass solution of the phenol-based or amine-based compound 15. Next, the kraft paper on which the adsorbing layer 13 was formed was immersed in the solution for 5 minutes, then taken out and the solvent was dried to attach a phenolic or amine compound to both sides of the kraft paper. Next, kraft paper with phenolic or amine compound attached is heated in a thermostat (held at 110 ° C for 24 hours) to chemically bond the amine compound of adsorption layer 13 with phenolic or amine compound 15 I let you. Finally, the excess phenol-based or amine-based compound was washed away with the previous solvent (acetone) to produce the electrical insulating paper 10 (Examples 1 to 12) of the present invention. The configurations of Examples 1 to 12 are shown in Table 1 described later.

(Production of electrical insulating paper of Comparative Examples 1 to 6)
Untreated kraft paper (kraft paper in which neither the adsorption layer 13 nor the antioxidant layer 16 was formed) was used as the electrical insulating paper of Comparative Example 1 as a reference. The kraft paper on which only the adsorption layer 13 (dicyandiamide) was formed (the kraft paper on which the adsorption layer 13 was formed but the antioxidant layer 16 was not formed) was used as the electrically insulating paper of Comparative Example 2. The kraft paper on which only the antioxidant layer 16 was formed (craft paper on which the antioxidant layer 16 was formed without forming the adsorption layer 13) was used as the electrical insulating paper of Comparative Examples 3-4. In addition, a phenolic or amine-based compound having no hydrophilic functional group (each compound name: 2,6-di-tert-butyl-p-cresol, N-phenyl-2-naphthylamine) is used for the adsorption layer 13 Electricity of Comparative Examples 5 to 6 (craft paper having dicyandiamide) and an antioxidant layer 16 (craft paper having no chemical bond 14 between the adsorption layer 13 and the adsorption layer 13 and the antioxidant layer 16 adsorbed) Insulated paper.
The configurations of Comparative Examples 1 to 6 are also shown in Table 1.

[Test / Evaluation]
(Investigation of formation amount of antioxidant layer)
In the electrical insulating paper produced above (Examples 1 to 12 and Comparative Examples 1 to 6), the amount of formation of the antioxidant layer was investigated by two methods. One method is to use a Fourier transform infrared spectrophotometer (FT-IR, manufactured by PerkinElmer Japan, Model 100) and measure the spectrum in the region of 4000 to 600 cm ^-1 by the attenuated total reflection method (ATR method). Went. When the antioxidant layer is sufficiently formed, it is derived from the spectrum derived from the phenolic or amine compound constituting the antioxidant layer, the spectrum derived from the amine compound constituting the adsorption layer, and the cellulose constituting the kraft paper. A spectrum was expected to be observed. The confirmed spectrum results are shown in Table 2 below.

  In another method, an increase in mass relative to the insulating paper before the formation of the antioxidant layer was measured using an electronic balance (manufactured by Sartorius Co., Ltd., model R200D). The dimension of the measurement sample was 20 mm × 20 mm. The used electronic balance has a minimum scale of 0.01 mg, and the mass is displayed by rounding off one digit below the minimum scale (that is, 0.001 mg). The results are also shown in Table 2.

(Evaluation of insulating oil impregnation)
As an index of the impregnation property of the electric insulating oil into the electric insulating paper, the permeability of the electric insulating oil was evaluated. In the electrical insulating papers of Examples 1 to 12 and Comparative Examples 1 to 6, after 5 μL of mineral oil was dropped on one surface of the insulating paper and allowed to stand for 10 minutes, the FT-IR was applied to the back surface of the insulating paper. The spectrum was measured in the region of 4000 to 600 cm ⁻¹ by the ATR method. At that time, if a spectrum derived from the dripped mineral oil can be observed, it can be considered that the mineral oil has impregnated the insulating paper and has reached the back surface. The thing in which the spectrum derived from mineral oil was observed was determined to be “pass”. The results are also shown in Table 2.

(Evaluation of tensile strength)
Initial tensile strength was measured as an index of mechanical properties of electrical insulating paper. The tensile strength measurement was performed in accordance with the JIS standard number C2300. The tensile strength was shown as a relative value with the tensile strength of Comparative Example 1 electrical insulating paper (untreated kraft paper) as 100. The results are also shown in Table 2.

(Evaluation of dielectric breakdown strength)
The initial AC breakdown strength was measured as an index of the electrical properties of the electrical insulating paper. The dielectric breakdown strength was measured in accordance with the JIS standard number C2300. The AC breakdown strength was expressed as a relative value, with the AC breakdown strength of the electrical insulating paper (untreated kraft paper) of Comparative Example 1 being 100. The results are also shown in Table 2.

(Evaluation of heat-resistant temperature index)
The heat resistant temperature index was measured as an index of durability and heat resistance of the electrical insulating paper. The heat-resistant temperature index was evaluated according to the following procedure in accordance with JEC standard number 6151.

  After drying the insulating paper, first, as an electrical insulating oil, a silicone oil having a water content of 20 ppm or less was prepared by bubbling nitrogen gas and saturating. Next, the fully insulated electrical insulating paper was immersed in the silicone oil and sealed in a pressure vessel. After heating in a pressure vessel in the range of 150 to 180 ° C., the tensile strength of the electrical insulating paper was measured. The temperature and time at which the tensile strength was reduced by half were determined using the previously measured tensile strength of the electrical insulating paper of Comparative Example 1 (untreated kraft paper) as an initial value, and the temperature index after 20,000 hours was determined. The relative values based on the heat resistant temperature index of Comparative Example 1 are shown. The results are also shown in Table 2.

  As shown in Table 2, in Examples 1 to 12, a peak derived from an amine compound and a peak derived from cellulose were observed, and a peak derived from a phenol-based or amine-based compound was not observed. Also, in the mass increase measurement, an increase in mass could not be confirmed. As described above, the electronic balance used for mass measurement is a balance that displays 0.01 mg by rounding off the 0.001 mg place. From these facts, it is considered that the coatings in Examples 1 to 12 had a mass increase of 0.004 mg or less, and the amount of formation of the antioxidant layer was less than the detection limit by the ATR method of FT-IR. . In addition, when 0.004 mg was converted into the coating amount on the insulating paper, it was calculated to be 0.02% by mass or less based on the insulating paper. However, due to the characteristic that the weight of the insulating paper varies greatly depending on the moisture absorption state, it is considered that an error of about 1% by mass occurs in the weight measurement. Therefore, it can be said that the weight of the phenol-based or amine-based compound in Examples 1 to 12 is less than 1% by mass of the entire electrical insulating paper.

  In the evaluation of the insulating oil impregnation property, the electrical insulating papers of Examples 1 to 12 and Comparative Examples 1 to 6 were observed to have a spectrum derived from mineral oil by the FT-IR ATR method, and were judged as “pass”. Moreover, since there was no special difference in the spectrum of Examples 1-12 and Comparative Examples 1-6, it is thought that there is no difference in those impregnation properties.

  In the evaluation of the tensile strength, the tensile strengths of Examples 1 to 12 were within a range of ± 2% with respect to the tensile strengths of Comparative Examples 1 to 6, and it was confirmed that they were almost equivalent. Also, in the dielectric breakdown strength evaluation, the dielectric breakdown strengths of Examples 1 to 12 were within a range of ± 2% relative to those of Comparative Examples 1 to 6, and it was confirmed that they were almost equivalent.

  In the evaluation of the heat resistant temperature index, the heat resistant temperature index of Comparative Example 2 was 11K higher than that of Comparative Example 1. In Comparative Example 2, the adsorption layer was formed alone, and it is considered that the heat resistance was improved by the cellulose hydrolysis inhibition effect by the amine compound in the adsorption layer. On the other hand, Comparative Examples 3 to 4 were formed by forming an antioxidant layer alone, and almost no change was observed as compared with that of Comparative Example 1. The antioxidant action of the phenolic or amine compound in the antioxidant layer may have inhibited the cellulose oxidation reaction, but the phenolic or amine compound is not fixed on the insulating paper surface. It is considered that the effect was hardly obtained because it was eluted and liberated in the oil.

  On the other hand, the heat-resistant temperature index of Examples 1 to 12 was about 18 to 25 K higher than that of Comparative Example 1. This is considered to be due to a synergistic effect of the cellulose hydrolysis inhibition effect by the adsorption layer amine compound and the antioxidant effect of the antioxidant layer.

  In Comparative Examples 5 to 6, the adsorption layer and the antioxidant layer are formed as in Examples 1 to 12, but the heat-resistant temperature index is only about 13 to 14 K higher than that of Comparative Example 1. However, this was an increase in the heat resistant temperature index of 2 to 3K as compared with the case where the adsorption layer of Comparative Example 2 was formed alone. In Comparative Examples 5 to 6, since the antioxidant layer is not fixed to the adsorption layer through a chemical bond, the phenolic or amine compound is eluted and liberated in the insulating oil, and has a sufficient antioxidant effect. It is thought that it was not obtained.

  As described above, according to the present invention, an electrical insulating paper having mechanical properties, electrical insulating properties, and impregnation properties of insulating oil equivalent to those of the prior art, and having durability and heat resistance superior to those of the prior art. It was confirmed that we can provide. In addition, by using the electrical insulating paper, it is possible to provide an oil-filled static induction appliance that can cope with high efficiency, large capacity, and / or downsizing.

  The above-described embodiment has been specifically described to help understanding of the present invention, and the present invention is not limited to having all the configurations described. For example, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Furthermore, a part of the configuration of each embodiment can be deleted, replaced with another configuration, or added with another configuration.

10 ... electric insulating paper, 11 ... cellulose, 12 ... paper substrate, 13 ... adsorption layer,
14 ... chemical bond, 15 ... phenolic or amine compound, 16 ... antioxidation layer,
21 ... Iron core, 22 ... Lower support bracket, 23a, 23b ... Insulation support base,
24a, 24b ... spacer between coils, 25a, 25b ... disc coil, 26 ... low voltage winding,
27a, 27b ... electrostatic shield, 28 ... straight spacer, 29 ... insulating cylinder, 210 ... main insulation,
211 ... High voltage winding, 212 ... Upper support bracket, 213 ... Push bolt,
214 ... High-voltage lead wire, 215 ... High-pressure bushing, 216 ... Supporting arm, 217 ... Spacer,
218 ... Lead wire barrier, 220 ... Transformer body container,
30 ... insulated wire, 31 ... conductor, 32 ... insulation coating.

Claims (9)

A paper substrate based on cellulose;
An adsorption layer formed by adsorption on the surface of the paper substrate;
An electrically insulating paper comprising a phenol-based or amine-based compound bonded to the adsorption layer through a chemical bond. The electrically insulating paper according to claim 1,
The electrical insulating paper, wherein the adsorption layer is made of an amine compound. The electrically insulating paper according to claim 2,
The electrically insulating paper, wherein the amine compound contains at least one of urea, thiourea, hexamethylenetetramine, melamine, dicyandiamide, and polyacrylamide. The electrical insulating paper according to any one of claims 1 to 3,
The chemical bonds are ether bonds (—O—), ester bonds (—COO—), carbonyl bonds (—CO—), amide bonds (—CONH—), imide bonds (—CONHCO—), imine bonds (—C). = Electrically insulating paper, comprising at least one of (N-) and (-COHCNH-) bonds. The electrical insulating paper according to any one of claims 1 to 4,
The electrically insulating paper, wherein the phenol-based or amine-based compound before being bonded to the adsorption layer has a hydrophilic functional group at a terminal. The electrically insulating paper according to claim 5,
The electrical insulating paper, wherein the hydrophilic functional group includes at least one of an aldehyde group (—CHO), a hydroxyl group (—OH), a carboxyl group (—COOH), and a glycidyl group (epoxy group). The electrical insulating paper according to any one of claims 1 to 6,
The electrical insulating paper, wherein the phenol-based or amine-based compound contains phenols or aromatic amines. The electrical insulating paper according to any one of claims 1 to 7,
The electrical insulating paper, wherein the total weight of the chemical bond and the phenolic or amine compound is less than 1% by mass with respect to the paper substrate. An electrical insulating paper according to any one of claims 1 to 8, an iron core, a conductor winding, and an electrical insulating oil,
The static induction machine characterized in that the electrical insulating paper is immersed in the electrical insulating oil.

Images