JPS5936361B2 - Mica thin leaf material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention uses mica thin sheets used as electrical insulating materials, particularly modified synthetic mica that can react with impregnating resins such as epoxy resins, to improve mechanical properties, heat resistance, etc. The invention relates to thin mica materials.

Conventionally, when mica is used as an electrical insulating material, it is mainly used as mica paper, mica tape, or mica board, but among these, mica paper used as a thin sheet material and mica thin sheet materials such as mica tapes are Natural hagashima mica or natural laminated mica have been used.

These natural mica were chemically extremely inert and showed no reactivity with the impregnating resin. Therefore, in equipment such as generators that have an insulating structure using these mica thin sheets, blistering and mica peeling occur during use, resulting in a decrease in insulation properties and, in severe cases, dielectric breakdown. It was the cause. As a result of various studies to improve the above-mentioned drawbacks of natural mica, this invention led to the invention of a modified synthetic mica that has reactivity with, for example, epoxy resin, which is commonly used as an impregnating resin. We have successfully developed mica thin leaf material using

The gist of this invention is to obtain a modified synthetic mica, which is obtained by replacing the inorganic interlayer ions of synthetic mica with organic groups, and bonding to a thin leaf-shaped substrate, the modified synthetic mica having reactivity with the impregnating resin used during impregnation.

When this thin mica material is used as a tape, for example, and wound around a conductor and heated to harden the resin after being impregnated with resin, the modified synthetic mica causes a chemical reaction with the impregnated resin, and the two are bonded together by a chemical bond. An extremely strong bond arises between them. Therefore, the aforementioned blistering and peeling phenomena of the insulating structure do not occur at all, and an extremely excellent insulating structure can be created. The characteristics of the mica thin leaf material according to this invention are (
1) Since the modified synthetic mica reacts with an impregnating resin such as an epoxy resin, an insulating structure with excellent mechanical properties can be obtained.

(2) The crosslinking of the impregnated resin is promoted by the reaction with the modified synthetic mica, so the heat resistance of the insulating structure is improved.

(3) The tensile strength of the mica tape is comparable to that of conventional mica using natural mica, and the workability of taping is also excellent.

(4) Modified synthetic mica exhibits impregnating properties equivalent to conventional natural mica, so the resin impregnating properties of mica thin leaf materials using finely divided modified synthetic mica are extremely good.

Many of these excellent features are derived from the properties of modified synthetic mica.

The thin substrate is not particularly limited, and any conventionally used nonwoven fabrics such as polyester and polyamide, cotton fabric, nylon fabric, glass cloth, insulating paper, polyimide film, polyester film, etc. can be suitably used. I can do it. Further, the modified synthetic mica is synthesized as described in detail below, and it is preferably made into a foil shape using a paper machine, for example. Furthermore, when bonding these thin leaf-shaped substrates and modified synthetic mica, it is possible to suitably perform the process by using various synthetic resins such as epoxy resins, modified phenolic resins, silicone modified epoxy resins, polyester resins, etc. as binders. . The modified synthetic mica used in this invention can be obtained by the following treatment.

The synthetic mica mentioned here includes tetrasilismic mica and taeniolite, which are types of fluorine mica that can be artificially synthesized, and hectorite, which is a type of synthetic montmorillonite, and these have a unique crystal structure. It has the unique property of infinitely swelling in water to form a sol and exchanging interlayer ions.

These compounds are made by blending silica, magnesia, and fluoride compounds (for example, lithium fluoride, sodium fluoride, calcium fluoride, or magnesium fluoride, etc.) or silica fluorides such as K2SiF6 and Na2SiF6 in a predetermined molar ratio, for example. 135 by internal thermoelectric melting method
It is synthesized by melting at 0 to 1400°C, and its chemical formula is as follows. In the structure, the charge balance between positive charges and negative charges is caused by the lack of positive charges and the presence of Na'', Li'' or Ca2f between the layers of the three-layer lattice, that is, between adjacent layers.
coordinates to maintain charge balance.

This bond between the layers is extremely weak, and when hydrated, a large amount of hydration water is drawn between the layers, causing swelling, and eventually the interlayer The bonds between the particles break and the particles open up, becoming ultra-fine particles to form a sol in water. Furthermore, since these interlayer ions are 12-coordinate electrostatic bonds coordinated at the center of the hexagonal network arrangement of oxygen ions in the upper and lower layers, they easily dissociate and exchange with other inorganic and organic cations.
Using this characteristic, the modified synthetic mica substituted with an organic group used in the present invention can be obtained by exchanging the inorganic interlayer ions of the various synthetic micas with various organic cations. The organic cations are typically inorganic or organic acid salts of primary to tertiary amines and quaternary ammonium salts, but oxonium salts, sulfonium salts, phosphonium salts, etc. can also be used.

A feature of the present invention is the use of the above-mentioned organic cation having a functional group in its molecule that can chemically bond with the impregnating resin used during impregnation. The type of the tube functional group is appropriately selected depending on the impregnating resin used, and examples include epoxy resin, silicone-modified epoxy resin, polyester resin,
In the case of alkyd resins, phenolic resins, epoxy-modified phenolic resins, etc., carboxyl groups, hydroxyl groups, amino groups, imino groups, acid anhydride groups, epoxy groups, isocyanato groups, alkyl groups, etc. are suitable. Specific examples of organic cations having carboxyl groups include amino acids such as ε-amino-n-caproic acid, glutamic acid, N-myristyl-β-alanine, and N-laurylglycine. dodecyldimethylcarboxymethylammonium chloride, stearyl betaine, amphoteric surfactants such as imidazoline type Amogen 88 (Daiichi Kogyo Seiyaku KK), chelates such as ethylenediaminetetraacetic acid, ethylenediaminetetrapropionic acid, etc. Examples include inorganic or organic acid salts of alkanolamines such as ethanolamine, propanolamine, butanolamine, and ethylene oxide or propylene oxide adducts of various amines. There are inorganic or organic acid salts, choline chloride, quaternary ammonium salts made by quaternizing the above amines such as Esocard 8 (Lion Agzo KK), and those with amino groups and imino groups include ethylenediamine and hexamethylenediamine. ,N,
Examples include inorganic or organic acid monosalts of diamines such as N-dimethylaminopropylamine, inorganic or organic acid partial salts of polyalkylene polyamines such as diethylenetriamine and triethylenetetramine, and examples of alkyl groups include cetyltrimethylammonium chloride and stearyltrimethyl. Examples include cationic surfactants made of quaternary alkyl ammonium salts such as ammonium chloride. When these organic cations are added to synthetic mica dispersed in water or a polar organic solvent, preferably on the acidic side, at room temperature or under heating and brought into contact with stirring, a cation exchange reaction occurs immediately, resulting in modified synthetic mica. is obtained.

The cation exchange capacity of the synthetic mica used here is 10 to 2.
50 milliequivalents/1009. Any of the solid modified synthetic mica described above can be suitably used. This invention will be described in detail below with reference to Examples.

Example 1 The results of investigating the reactivity of modified synthetic mica and epoxy resin will be described.

Calcium tetrasilicate squid modified with dodecyldimethylcarboxymethylammonium chloride 2
Mix 5 parts of bisphenol A diglycidyl ether type epoxy resin Epicoat #8288, 75 parts,
The exothermic curve was measured with a differential calorimeter. The results were as shown in curve 1 in the figure. From this curve 1, it can be seen that modified synthetic mica reacts with the epoxy resin even when it is used alone. When the sample was taken out after the measurement, it turned out to be a solid although somewhat soft, and from this fact it is clear that the modified synthetic mica reacts with the epoxy resin. Curve 2 in the figure shows the exothermic curve of a mixture of 25 parts of natural aggregated mica and Epicote #828875 for reference, and it is confirmed from this curve 2 that natural aggregated mica does not react with the epoxy resin at all. Ta. Example 2 A mica tape was made by laminating a mica foil made by making the modified synthetic mica described in Example 1 using a paper machine to a polyester nonwoven fabric used as a thin leaf-like base with an epoxy resin as an interlayer. .

When this mica tape was taped onto a rectangular copper wire and impregnated with an epoxy resin, the workability of taping was excellent and the impregnating property of the resin was also extremely good. In general, in a composite insulator impregnated with a resin, the quality of the impregnation state is determined by the tail δH), the dielectric loss tangent when a certain high voltage is applied to the impregnated material, and the corona discharge due to fine voids in the impregnated material. This is determined by the difference in dielectric loss tangent, TanδA, when a low voltage that does not cause the occurrence of When we measured the voltage dependence of Tanδ at 5 kV
The dielectric current Anδ (5k
The dielectric loss tangent, Tan δ (0.5 kV/blade 1), was 0.42% when a voltage of 0.5 kV/n was applied. Therefore, "δH = T
anδ (5kV/I) - Tanδ (0.5kV/I)〒
It was 0.40%. This value is slightly smaller than that of a composite insulator using a laminated mica tape made by laminating a polyester nonwoven fabric with an epoxy resin as a binder to a laminated mica foil made by paper-making natural laminated mica for comparison. This shows that the impregnating properties of the resin are excellent.

On the other hand, the glass transition temperature of the composite insulator using the mica tape of the present invention was measured with a direct-reading viscoelastic spectrometer and found to be 139°C.

This value is significantly higher than the 117°C obtained for the composite insulator made using the above-mentioned laminated mica tape, which was prepared for comparison, and shows that the heat resistance is significantly improved by using modified synthetic mica. . Example 3 A mica tape was made by laminating mica foil made from sodium taeniolite modified with cetyltrimethylammonium bromide and insulating paper using an epoxy resin as a binder.

The workability of this mica tape during taping was extremely good, and the impregnability of the resin was also extremely good. Example 4 A mica tape was made by laminating a polyamide nonwoven fabric with an epoxy resin as a binder to a mica foil made by paper-making sodium taeniolite modified with triethylenetetramine.

The workability of this mica tape during taping was extremely good, and the impregnability of the resin was also extremely good. Example 5 A mica tape was made by laminating cotton cloth to a mica foil made by paper-making sodium tetrasilismic squid modified with pentaethylenehexamine and using an alkyd resin as a binder.

The workability of this mica tape during taping was extremely good, and the impregnability of the resin was also extremely good. Example 6 Lithium modified with ε-amino-n-caproic acid
Mica tape was made by laminating glass cloth to mica foil made by paper-making hectorite and using modified phenolic resin as a binder.

The workability of this mica tape during taping was extremely good, and the impregnability of the resin was also extremely good. Example 7 A mica tape was made by laminating a polyimide film using an epoxy-modified phenol resin as a binder to a mica foil made by paper-making sodium hectorite modified with trimethylhydroxyethylammonium chloride.

This mica tape had extremely good workability during taping and also had good resin impregnation properties. Example 8 A mica tape was made by laminating glass cloth with silicone-modified epoxy resin as a binder to a mica foil made by paper-making calcium tetrasilismic squid modified with N,N'-dimethylamino-n-propylamine. Ivy.

The workability of this mica tape during taping was extremely good, and the impregnability of the resin was also extremely good. Example 9 A mica tape was made by laminating a nylon cloth with a polyester resin as a binder to a mica foil made by paper-making calcium tetrasilismic squid modified with an imidazoline type surfactant, Amogen Ma88.

The workability of this mica tape during taping was extremely good, and the impregnability of the resin was also extremely good. Example 10 A mica tape was made by laminating a polyester fluoride film using an epoxy resin as a binder to a mica foil made by paper-making calcium tetrasilismic squid modified with dodecyldimethylcarboxymethylammonium chloride.

This mica tape had extremely good workability during taping and also had good resin impregnation properties. The dielectric loss tangent and glass transition temperature of the composite insulators prepared by impregnating the mica tape with epoxy resin in Examples 3 to 10 described above are summarized in a table. Looking at this, it can be seen that the properties of the mica tape according to the present invention are extremely excellent.

In the above embodiments, the present invention was explained in the form of a tape, but it goes without saying that the present invention is not limited to this, and the conductor used is not limited to rectangular copper wire. Furthermore, although the present invention can be effectively used as an electrically insulating material, it may also be used for other purposes. As explained above, this invention has the effect of improving heat resistance, mechanical properties, etc. by using modified synthetic mica in which the inorganic interlayer ions of synthetic mica are replaced with organic functional groups as the mica to be laminated to the substrate. be.

[Brief explanation of the drawing]

The figure shows an exothermic curve obtained by measuring the reactivity of modified synthetic mica or natural aggregate mica with an epoxy resin using a differential calorimeter. In the figure, curve 1 shows modified synthetic mica, and curve 2 shows natural aggregate mica.

Claims (1)

[Claims] 1. Modified synthetic mica obtained by substituting inorganic interlayer ions of synthetic mica with organic cations having a functional group capable of chemically bonding with the impregnating resin used for impregnation is attached to a thin leaf-like substrate. Mica thin leaf material that is characterized by 2. The mica thin sheet material according to claim 1, wherein a nonwoven fabric of synthetic fiber is used as the base material. 3. The mica thin sheet material according to claim 2, wherein a polyester nonwoven fabric is used as the synthetic fiber nonwoven fabric. 4. The thin mica material according to claim 1, wherein a synthetic resin film is used as the substrate. 5. The mica thin sheet material according to claim 4, wherein a polyester film is used as the synthetic resin film. 6. The thin mica material according to claim 1, wherein a glass cloth is used as the substrate. 7 Claim 1 in which the functional group is a carboxyl group
The mica thin leaf material according to any one of Items 6 to 6. 8. The mica thin leaf material according to any one of claims 1 to 6, wherein the functional group is a hydroxyl group.